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Journal articles on the topic "Carbides Effect of high temperatures on"
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Jiang, Zheng Yi, Xing Jian Gao, Dong Bin Wei, Sheng Li Li, Hong Mei Zhang, Jian Zhong Xu, Di Wu, and Si Hai Jiao. "Effect of Carbide Orientation on Sliding Wear Behaviour of High Chromium Cast Iron." Advanced Materials Research 1136 (January 2016): 567–72. http://dx.doi.org/10.4028/www.scientific.net/amr.1136.567.
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The effect of carbide orientation on the dry sliding wear behaviour of high chromium cast iron was studied by pin-on-disc type wear tests at room temperature. The carbide anisotropy was achieved by thermomechanical treatments at temperatures of 950 and 1150 °C. By cladding with low carbon steel, the brittle high chromium cast iron was hot compressed severely with crack free. The thermomechanical treatments not only change the carbide orientation, but also increase the volume fraction of carbides. Due to the long axis of carbide rods is parallel to the wear surface, the high chromium cast iron treated at 1150 °C has a superior wear resistance than the as-cast one, in which the long axis of carbides is perpendicular to the wear surface. For the high chromium cast iron treated at 950 °C, high volume fraction of carbide pits accelerates the wear rate significantly even though it has a similar carbide orientation as the sample treated at 1150 °C. The observations on wear tracks reveal that the ferrous matrix can be protected better from abrasion when the high chromium cast iron was treated at 1150 °C.
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Liu, Bowen, Tian Qin, Wei Xu, Chengchang Jia, Qiuchi Wu, Mingying Chen, and Zhe Liu. "Effect of Tempering Conditions on Secondary Hardening of Carbides and Retained Austenite in Spray-Formed M42 High-Speed Steel." Materials 12, no. 22 (November 11, 2019): 3714. http://dx.doi.org/10.3390/ma12223714.
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In this study, the effect of tempering conditions on microstructure, grain size, and carbide phase compositions of spray-formed high-speed steel after quenching at 1180 °C was studied. The influence of carbide phase, size of carbides, and retained austenite content on secondary hardening of the steel was analyzed by field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), electron backscattered diffraction (EBSD), and differential scanning calorimetry (DSC); the hardness, microhardness of carbide, and bending strength were tested. The results show that M3C, M6C, M7C3, and MC carbides may precipitate at different tempering temperatures and the transformation of the retained austenite can be controlled by tempering. The phase composition of carbides, microstructure, and retained austenite content strongly influences the performance characteristics of M42 high-speed steel after tempering. In contrast, the secondary carbides produced by tempering thrice at 540 °C are mainly M6C carbides rich in W and Mo elements, and the content of retained austenite is effectively reduced. At this stage, the Rockwell hardness reaches 67.2 HRC, bending strength reaches 3115 MPa, and the properties and microstructure are optimal.
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Pan, Yongliang, Tounan Jin, Naibo Yuan, Tiejun Ma, and Hanguang Fu. "Effect of austenitizing temperature on microstructure and properties of a high-speed cobalt steel." Materials Testing 64, no. 8 (August 1, 2022): 1122–35. http://dx.doi.org/10.1515/mt-2021-2187.
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Abstract The effect of different austenitizing temperatures on the type, morphology, distribution of carbides and martensite content in cobalt high-speed steel is characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and energy dispersive spectrometry. The results show that the eutectic MC carbides hardly dissolve during austenitizing process, and the lamellar M2C carbides decompose into MC and M6C carbides at 1100 °C. A large amount of M23C6 carbides uniformly distributed on the matrix are dissolved into austenite at 1100 °C. With the increase of austenitizing temperature, alloy element dissolves into matrix and the effect of solid solution strengthening of martensite enhances, which increases the hardness of cobalt high-speed steel. However, when the austenitizing temperature exceeds 1050 °C, the excess alloying elements in the matrix reduce the Ms point and increase the volume fraction of retained austenite, resulting in decrease of hardness of cobalt high-speed steel. The peak hardness with 66.4 HRC appears when the austenitizing temperature reaches 1050 °C.
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Dudko, Valeriy, Diana Yuzbekova, Sergey Gaidar, Sofia Vetrova, and Rustam Kaibyshev. "Tempering Behavior of Novel Low-Alloy High-Strength Steel." Metals 12, no. 12 (December 17, 2022): 2177. http://dx.doi.org/10.3390/met12122177.
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The effect of tempering on the mechanical properties, structure, and dispersion of secondary phase particles is studied in 0.4%C-2%Si-1%Cr-1%Mo-VNb steel. This steel austenitized at 900 °C with subsequent water quenching exhibits a yield stress of 1445 MPa and a lath martensite structure with MX particles of ~40 nm located in matrix and boundary M6C carbides of ~210 nm. Tempering in the temperature interval of 200–400 °C provides a yield stress of 1625 MPa due to the precipitation of ε-carbide and cementite within laths. The yield stress decreases to 1415 and 1310 MPa after tempering at 500 and 650 °C, respectively, due to the replacement of matrix carbides by boundary M23C6 carbide. A Charpy V-notch impact energy of ~12 J/cm2 is almost independent from tempering temperatures of up to 400 °C and increases up to ~33 J/cm2 after tempering at 650 °C due to decreased yield stresses and increased plasticity.
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Hu, Qipeng, Miaohui Wang, Yunbo Chen, Hailong Liu, and Zhen Si. "The Effect of MC-Type Carbides on the Microstructure and Wear Behavior of S390 High-Speed Steel Produced via Spark Plasma Sintering." Metals 12, no. 12 (December 16, 2022): 2168. http://dx.doi.org/10.3390/met12122168.
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The microstructure and wear behavior of S390 high-speed steel (HSS) reinforced with different volume fractions of MC-type carbides produced via spark plasma sintering were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) in this study. SEM and TEM results show that V-W-rich carbides are formed around the added MC-type carbides, and these carbides have a similar composition to the M(C, N) carbides precipitated at high temperatures according to thermodynamic calculations. Both macrohardness and three-point bending results show that the carbide type is the dominant factor increasing the hardness, and the volume fraction of the carbide is the dominant factor leading to a decrease in the three-point bending strength. The wear mechanism of HSS metal matrix composites (MMCs) is confirmed as abrasive wear and oxidative wear via wear tracks and oxidation films. Compared with the sample without reinforcement (85 HRA, wear coefficient of 1.50 × 10−15 m2/N), the best MT-3 sample exhibits a hardness increase of 1.8 HRA and a three-fold increase in wear resistance.
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Romanenko, Dmitriy N., Victor V. Gorozhankin, and Marina V. Nalimova. "Hardenability and Wear Resistance of Carburized to Hypereutectic Concentrations Steels." Solid State Phenomena 299 (January 2020): 330–34. http://dx.doi.org/10.4028/www.scientific.net/ssp.299.330.
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In this article the experimental data of the hardness and wear resistance of chrome-manganese steels 35H3G2F and 35HGF, which are cemented in a highly active paste-like carburizer and hardened at various temperatures, are presented. Cementation and high temperature carbonitriding of these steels leads to a high content of the carbide phase in the diffuse layers and an increase of hardness and wear resistance. The effect of carbides on the hardenability of diffuse layers are investigated. The hardening temperature ranges of these steels and the effect of alloying elements on hardness are established. The mechanism of the phase formation of the highest hardness structures is described. The carbides influence on the wear mechanism of cemented in various modes steels is studied.
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Cheng, Xiaole, Dong Zhang, Xiaojun Wu, Guangshen Xu, and Hanguang Fu. "Effect of quenching temperature on microstructure and properties of low silicon hypereutectic high chromium cast iron." Metallurgical Research & Technology 120, no. 1 (December 9, 2022): 102. http://dx.doi.org/10.1051/metal/2022105.
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In this paper, the effects of different quenching temperatures on the microstructure and properties of Fe–4.0C–35.0Cr–0.5Si (wt.%) low-silicon hypereutectic high-chromium cast iron (LS-HHCCI) was investigated. The effect of quenching temperature on the microstructure of LS-HHCCI was analyzed by optical microscope, scanning electron microscope, and X-ray diffractometer. After quenching at different temperatures, the hardness and wear resistance of LS-HHCCI were tested by Rockwell hardness tester, microhardness tester, and wear testing machine. The results show that the microstructure of as-cast LS-HHCCI is mainly composed of austenite matrix and M7C3 carbides. After quenching, the austenite matrix is transformed into martensite, and M23C6 type secondary carbides are precipitated in the matrix. As the quenching temperature increased from 950 °C to 1100 °C, the eutectic carbides first appeared as fine needles, and then they gather and grow up, showing elongated or lumpy. The hardness and abrasion resistance first increase and then decrease, it reached peak values of 67.2 HRC at the temperature of 1050 °C, while the wear resistance is the best.
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Tóth, László, and Réka Fábián. "The Effects of Quenching and Tempering Treatment on the Hardness and Microstructures of a Cold Work Steel." International Journal of Engineering and Management Sciences 4, no. 1 (March 3, 2019): 286–94. http://dx.doi.org/10.21791/ijems.2019.1.36.
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The X153CrMoV12 ledeburitic chromium steel characteristically has high abrasive wear resistance, due to their high carbon and high chromium contents with a large volume of carbides in the microstructure. This steel quality has high compression strength, excellent deep hardenability and toughness properties, dimensional stability during heat treatment, high resistance to softening at elevated temperatures. The higher hardness of cryogenic treated samples in comparison with conventional quenched samples mean lower quantity of retained austenite as at samples quenched to room temperature and tempered in similar condition. In the microstructure of samples were observed that the primary carbide did not dissolve at 1070°C and their net structure have not been changed during to heat treatment. During to tempering at high temperature the primary carbides have become more and more rounded. After low tempering temperature in martensite were observed some small rounded carbides also, increasing the tempering temperature the quantity of finely dispersed carbides increased, which result higher hardness. The important issues in heat treatment of this steels are the reduction or elimination of retained austenite due to cryogenic treatment.
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Li, Shaoying, Xiaojun Xi, Yiwa Luo, Mingtao Mao, Xiao Shi, Jing Guo, and Hanjie Guo. "Carbide Precipitation during Tempering and Its Effect on the Wear Loss of a High-Carbon 8 Mass% Cr Tool Steel." Materials 11, no. 12 (December 7, 2018): 2491. http://dx.doi.org/10.3390/ma11122491.
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In this paper, the precipitation of carbide and wear loss of high-carbon 8 mass% Cr tool steel at two tempering conditions (i.e., 773–803 K and 823–853 K) were studied by INCA Steel, EPMA-1720H, XRD, and ML-10 tester. The results show that the particles of test steels include the carbides (Cr7C3 and Cr23C6) and carbides nucleated on Al2O3. When carbides are of the same size, the number of carbides in test steel at a tempering temperature of 773–803 K is greater than that at a tempering temperature of 823–853 K, especially when the size of carbides is less than 5 μm. Compared with the test steel tempered at 823–853 K, the distance between adjacent actual particles reduced by 80.6 μm and the maximum amount of reduction was 9.4% for single wear loss at the tempering temperature of 773–803 K. It can be concluded from thermodynamics results that Al2O3 inclusions began to precipitate in liquid, and the precipitation of carbides was at the solid–liquid region. Al2O3 can be used as the nucleation interface of carbide, thus promoting the formation of carbides. During the cooling of molten steel, a lower temperature can increase the difference of actual solubility product bigger than equilibrium solubility product, thus promoting the carbide formation.
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Liu, Yang, Lei Wang, Yu Chen Wang, Hong Yan Liu, Xue Jiao Chen, and Yan Yu. "Effects of Electropulsing Treatment on the Precipitation Behaviour of Grain Boundary Carbides in GH3044 Alloy." Materials Science Forum 654-656 (June 2010): 464–67. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.464.
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The effects of electropulsing treatment on the precipitation behaviour of grain boundary carbides in GH3044 alloy were investigated. The results showed that the initial temperature of precipitation of M23C6 type carbides on grain boundary could be decreased by electropulsing treatment under the condition of high current density of 10.0kA/mm2 with a frequency of 5Hz and pulse width of 15s. The volume percentage of M23C6 type carbide was greatly increased to 274.60% comparing with that of the aging treatment at the same temperature. However, the precipitation of M23C6 type carbide was inhibited by electropulsing treatment under the condition of high frequency of 45Hz with the current density of 2kA/mm2 and pulse width of 15s. The volume percentage of M23C6 type carbide was decreased to 18.81% comparing with that of the aging treatment at the same temperature. It has been found that the diffusion of solute atom in the alloy can be promoted by the electric effect with the electropulsing. As a result, the thermodynamic condition and kinetics of the precipitation of M23C6 type carbide were changed, and both the initial and peak temperatures of precipitation were decreased.
Dissertations / Theses on the topic "Carbides Effect of high temperatures on"
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Wingbrant, Helena. "Development of high temperature SiC based field effect sensors for internal combustion engine exhaust gas monitoring." Licentiate thesis, Linköping University, Linköping University, Applied Physics, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-4673.
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While the car fleet becomes increasingly larger it is important to lower the amounts of pollutants from each individual diesel or gasoline engine to almost zero levels. The pollutants from these engines predominantly originate from high NOx emissions and particulates, in the case when diesel is utilized, and emissions at cold start from gasoline engines. One way of treating the high NOx levels is to introduce ammonia in the diesel exhausts and let it react with the NOx to form nitrogen gas and water, which is called SCR (Selective Catalytic Reduction). However, in order to make this system reduce NOx efficiently enough for meeting future legislations, closed loop control is required. To realize this type of system an NOx or ammonia sensor is needed. The cold start emissions from gasoline vehicles are primarily due to a high light-off time for the catalytic converter. Another reason is the inability to quickly heat the sensor used for controlling the air-to-fuel ratio in the exhausts, also called the lambda value, which is required to be in a particular range for the catalytic converter to work properly. This problem may be solved utilizing another, more robust sensor for this purpose.
This thesis presents the efforts made to test the SiC-based field effect transistor (SiC-FET) sensor technology both as an ammonia sensor for SCR systems and as a cold start lambda sensor. The SiC-FET sensor has been shown to be highly sensitive to ammonia both in laboratory and engine measurements. As a lambda sensor it has proven to be both sensitive and selective, and its properties have been studied in lambda stairs both in engine exhausts and in the laboratory. The influence of metal gate restructuring on the linearity of the sensor has also been investigated. The speed of response for both sensor types has been found to be fast enough for closed loop control in each application.
On the day of the public defence of the doctoral thesis, the status of article III was: in press. Report code: LiU-Tek-Lic-2003:50.
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Mellin, Hannu Kaarlo Olavi. "The effect of high temperatures (30 degrees Celsius) on biological nutrient removal performance." Master's thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/21729.
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The main objective of this investigation was to evaluate activated sludge biological nutrient removal (BNR) performance at elevated temperatures for possible application of nitrification denitrification (ND) and ND biological excess phosphorus removal (NDBEPR) systems to municipal wastewater treatment in the equatorial and tropical regions or to combined treatment of municipal and anaerobically (thermophilic) pretreated paper and pulp industry wastewaters in the very cold northern forested regions. To accomplish this objective, a ND Modified Ludzack Ettinger (MLE) system and a NDBEPR University of Cape Town (UCT) system were operated at 30°C and 10 days sludge age for a period of 582 days. During the investigation 41 sewage batches, each lasting about two weeks, of real sewage from the Mitchells Plain municipal wastewater treatment plant (Western Cape, South Africa) were fed to the systems. The two systems were sampled and tested ,almost daily for Chemical Oxygen Demand (COD), Total Kjeldahl Nitrogen (TKN), Free and Saline Ammonia (FSA), nitrate, nitrite, Total Phosphorus, Volatile Settleable Solids (VSS), Total Settleable Solids (TSS), pH, Oxygen Utilization Rate (OUR) and diluted sludge volume index (DSVI) in the influent, anaerobic, anoxic and aerobic reactors and effluent as appropriate. Also, in order to determine the kinetic rates of nitrification, denitrification and readily biodegradable COD (RBCOD) conversion to Volatile Fatty Acids (VF A), aerobic, anoxic and anaerobic batch tests were conducted at 30°C on sludge harvested from the two systems and microscopic examination of the sludges was undertaken every four weeks to identify the filamentous organisms in the systems.
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Krishnamoorthy, Vijay. "Effect of gas density on corrosion in horizontal multiphase slug flow at high temperatures and pressures." Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1177096097.
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Fry, J. C. "A study of the cooling effect of water sprays on steel strip at high temperatures." Thesis, Swansea University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637015.
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To meet customers' demands for increased quality and product consistency, together with the production of a wider range of steels there is a need for accurate temperature control throughout the whole cooling path on the hot Strip Mill. This requires a cooling system that couples the required cooling rate with the heat transfer capabilities of the water spray system and the production speed and line length, however, information on the heat transfer characteristics of water sprays is sparse. Therefore, the project described in this thesis has investigated the heat transfer characteristics of water sprays. The project has been two fold. Initially a steady state test apparatus has been designed, built and commissioned which allows the heat transfer coefficient of a single pressure atomised water spray to be evaluated under various operating conditions. Secondly, the apparatus has been used to conduct experiments on two commercially available spray nozzles with the aim of determining the relationship between the spray operating conditions and the heat transfer coefficient. The work has demonstrated that a steady state technique can be used to determine the heat transfer coefficient of a spray at surface temperatures between 650°C and 950°C. The experimental work has shown that the heat transfer coefficient increases with increasing surface temperature, increasing flow rate and decreasing stand off distance. For the two nozzles tested correlation equations have been derived which allow the heat transfer coefficient to be evaluated in terms of the surface temperature, flow rate and stand off distance. Finally, the application of the correlation equations to the design and improvement of water cooling lines has been considered.
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Peng, Yucheng. "EFFECT OF HIGH TEMPERATURES ON ADHESIVE BOND DURABILITY AND TOXIC CHEMICAL PRODUCTION FOR ENGINEERED WOOD PRODUCTS." MSSTATE, 2008. http://sun.library.msstate.edu/ETD-db/theses/available/etd-07082008-153319/.
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The objectives of this research were to investigate the heat resistant performance of a structural adhesive and to analyze the contribution of the adhesive to the chemical emissions from the glued wood products affected by the elevated temperatures. Phenol-resorcinol-formaldehyde (PRF) and two wood species, southern pine (Pinus palustris) and Douglas-fir (Pseudotsuga menziesii), were investigated. The dynamic mechanical analysis (DMA) test results showed that the heat durability performance of cured PRF resin was better than that of the two wood species used in this study. The results indicated that the fire safety of PRF bonded wood products should be comparable to solid wood products. The pyroysis products obtained from pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) system showed that most of the pyrolysis products of glued wood samples were same as those of wood and adhesive samples at the same temperature level except a few compounds, such as carbon disulfide, Cyclopropyl carbinol, acetaldehyde, furfural and others.
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Lindsay, John Christopher. "Stress corrosion cracking and internal oxidation of alloy 600 in high temperature hydrogenated steam and water." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/stress-corrosion-cracking-and-internal-oxidation-of-alloy-600-in-high-temperature-hydrogenated-steam-and-water(1d6b037c-baf1-4397-a6c9-43835e7bb39a).html.
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In this study, the possibility of using low pressure hydrogenated steam to simulate primary water reactor conditions is examined. The oxides formed on Alloy 600 (WF675) between 350 Celsius and 500 Celsius in low pressure hydrogenated steam (with a ratio of oxygen at the Ni/NiO to oxygen in the system of 20) have been characterised using analytical electron microscopy (AEM) and compared to oxide that formed in a high pressure water in a autoclave at 350 Celsius with 30 cc/kg of hydrogen. Preferential oxidation of grain boundaries and bulk internal oxidation were observed on samples prepared by oxide polishing suspension (OPS). Conversely, samples mechanically ground to 600 grit produced a continuous, protective oxide film which suppressed the preferential and internal oxidation. The surface preparation changed the form of the oxides in both steam and autoclave tests. The preferential oxidation rate has been determined to be K_{oxide} = Aexp{-Q/RT}with A = 2.27×10^(−3) m^(2)s^(−1) and Q = 221 kJ.mol^(−1) (activation energy) for WF675 and A = 5.04 × 10^(−7) m^(2)s^(−1) and Q = 171 kJ.mol^(−1) for 15% cold worked WF675. These values are consistent with the activation energy of primary water stress corrosion cracking (PWSCC) initiation. Bulk oxygen diffusivities were calculated from the internal oxidation after 500 h exposures. At 500 Celsius the oxygen diffusivity was determined to be 1.79×10^(−20) m^(2)s^(−1) for WF675 and 1.21×10^(−20) m^(2)s^(−1) for 15% cold worked WF675, the oxygen diffusivity at 400 Celsius in 15% cold worked WF675 was calculated to be 1.49×10^(−22) m^(2)s^(−1).The Cr-depletion associated with preferential oxidation has been assessed by AEM. The Cr-depletion was asymmetric and it could not be accounted for by local variations in the diffusion rate. Chemically induced grain boundary migration is suggested as a possible explanation. Constant load SCC tests conducted in hydrogenated steam at 400 Celsius have shown a similar trend to the classical dependency of PWSCC as a function of potential. The SCC samples were also prepared with two surface finishes, OPS and 600 grit. In all SCC tests, significantly more cracking was observed on the OPS surface and all failures initiated from this surface.
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Karkhanis, Shalmira. "Macroscopic and microscopic changes in incinerated deciduous teeth." University of Western Australia. Centre for Forensic Science, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0170.
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The teeth are amongst the most resilient elements of the human skeleton and are thus often utilised in routine forensic investigation involving the identification of unknown remains. The teeth, however, also have other practical forensic applications. Teeth exposed to thermal stress have the potential to not only aid in identification but also in understanding the circumstances surrounding the fire. Previous investigations have drawn conclusions that if a fire flares up suddenly and intensively, the teeth burst and enamel is lost. If the blaze commences gently and burns slowly, then the first observable morphologic change is the colour. The teeth subsequently are difficult to handle, thus changes in teeth can indicate the history of exposure to thermal conditions. Children are twice as likely to become victims of house fire because of an inability to safely evacuate from areas of danger. The literature demonstrates, however, that research on the effects of incineration on teeth is mostly restricted to the permanent teeth. The apparent lack of knowledge on the effects of incineration on deciduous teeth thus necessitates further research in this area. This research project primarily aims at understanding the effect of extreme temperatures on deciduous teeth. It also aims to relate colour changes that occur post heating with fragility to aid in proper handling of samples in a forensic scenario and to determine the possibility of identifying incineration temperature based on tooth condition. The samples analysed composed of 90 deciduous teeth (45 molars and 45 anteriors) extracted as a part of clinical treatment were used for the study. The project involved exposing extracted deciduous teeth to temperatures ranging from 100°C to 1100°C for 30 minutes using a laboratory Gallenkamp oven. Unheated deciduous teeth were used as controls for the project. Post-incineration the teeth were then analysed under a stereomicroscope and SEM for morphological changes. A colorimetric analysis was also undertaken to evaluate the colour changes induced in the primary teeth due to the thermal stress. It was found that it was possible to identify the incineration temperature based on the tooth condition when the colour changes, stereomicroscopic findings and SEM images were utilised collectively. It was also concluded that the thermally induced changes observed in primary teeth occur at lower temperatures in comparison to the permanent teeth. It was also established that post-incineration deciduous teeth are fragile and show a tendency to fragment after minimal exposure to thermal stress as compared to the permanent teeth. Moreover enamel and dentin remained identifiable in primary teeth even after exposure to 1100°C for 30 minutes while cementum lost its structural morphology at 900°C.
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Laurent, Véronique. "Mouillabilité et réactivité dans les systèmes composites métal/céramique : étude du couple Al/SiC." Grenoble INPG, 1988. http://www.theses.fr/1988INPG0115.
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Etude experimentale du mouillage par la methode de la goutte posee et par une methode tensiometrique d'immersion-emersion. Analyse chimique et structurale des interfaces par spectrometrie auger, microsonde, microscopie electronique a balayage et en transmission. Influence de la temperature (973-1173k), de la composition de la phase metallique(additions de si, ti, cu et sn) et des traitements de surface de sic (recouvrement par des couches de silice ou carbure sur la cinetique de mouillage. Interpretation et generalisation des resultats par une approche thermodymique
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Pearson, Stephen R. "The effect of nitriding on the fretting wear of a high strength steel at ambient and elevated temperatures." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/29004/.
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This work is an experimental evaluation of the wear and friction of a high strength alloy steel (super-CMV (SCMV» in its as heat treated and plasma nitrided states under fretting conditions in air, at both ambient and elevated temperatures. In order to conduct the experimental programme, a new test rig and associated data processing and assessment capability was developed. Wearing couples in homogeneous and heterogeneous arrangements were tested to assess the effectiveness of the nitriding process as a fretting palliative-the heterogeneous mating is particularly representative of configurations found in aerospace transmission assemblies. A range of test conditions were examined with a line contact, including normal loads from 25 to 65Nmm-1, displacement amplitudes from 10 to 100 µm and temperatures from 24 to 450°C. At ambient temperatures, the wear behaviour was assessed using an energy-wear analysis, whereupon it was demonstrated that the wear volume was a linear function of the dissipated frictional energy (over the range of loading conditions) with a significant energy threshold before the onset of wear. Accordingly, the fretting wear over the full range of loading conditions could be described by a single wear rate and threshold value. The wear rate for homogeneous couples of nitrided super-CMV (SCMVN) was found to be 12 % lower than that for comparable SCMV pairings, although the lower threshold energy for the SCMVN case would lead to them suffering greater wear at < 2.5 kJ of dissipated energy (in the configuration examined). In heterogeneous couples, the harder SCMVN specimen was found to wear preferentially; while the SCMV specimen suffered severe plastic damage of the surface, a protective oxide debris bed was seen to form, which protected the underlying SCMV from wear and abraded the SCMVN specimen. At elevated temperatures, the tribology (of both SCMV and SCMVN) was dominated by the formation of a glaze-layer. The progressive formation of the glaze, with increasing temperature, led to a critical transition temperature (TT) above which a significant reduction in both the wear and friction of the materials was observed. For SCMV, after only a modest increase in temperature to 85 °C, the overall loss of material from the contact had become negative. At temperatures greater than 85°C, negative wear was maintained, with the coefficient of friction dropping monotonically until a slight minimum at 300°C. The behaviour for the SCMVN couples was very similar; the transition to negative wear occurred at a higher temperature of 150°C but the friction minimum was also found at 300°C. It is proposed that the changes in wear rate and friction coefficient were due to changes in the way that the oxide particles sintered to form a protective debris bed, with sintering of the oxide debris particles at these low temperatures being promoted by the nano-scale at which the oxide debris is formed.
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Tripp, David William. "The thermal regime during electron beam hearth remelting." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26748.
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Electron beam hearth remelting is extensively used in refining of superalloys, titanium alloys and the recycling of these materials. The removal of impurities and exhogenous particles during the hearth melting operation depends primarily on the time at temperature relationship developed within a pool of molten metal. In the past hearth melters have acted largely on empirical evidence to specify such parameters as melt rates, power levels and skull sizes. This work describes a mathematical model which could be used to predict certain parameters (such as pool volume or alloy element evaporation rates) when given skull geometry, power input and melt rate.
A three dimensional steady state heat transfer model of both the skull and water cooled copper mould during electron beam hearth remelting has been developed. The model has been used to investigate the effects of surface temperature, liquid motion, power input, skull geometry, presence of the hearth mould and melt rate on parameters such as pool volume during skull melting.
In general the choice of any combination of operating parameters depends on a balance between the refining capacity of the process (i.e. liquid volume) and the loss of alloy elements by evaporation. In the case of melting pure materials (e.g. CP titanium) the balance is between refining capacity and efficient energy use.
It was found that forced convection is significantly more effective in increasing the volume of the liquid pool than any other single parameter. Increasing the power input to the skull, increasing the skull width and removing the water cooled copper mould from around the skull also increase the pool volume. The evaporation rates of alloy elements within the skull were most effected by changes in the power distribution and the degree of liquid motion.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
Books on the topic "Carbides Effect of high temperatures on"
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Thermomechanics of composites under high temperatures. Dordrecht: Kluwer Academic Publishers, 1999.
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Bažant, Z. P. Concrete at high temperatures: Material properties and mathematical models. Harlow: Longman, 1996.
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3
G, Sumner, Livesey V. B, and Springfields Nuclear Power Development Laboratories., eds. Techniques for high temperature fatigue testing. London: Elsevier Applied Science Publishers, 1985.
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High temperature corrosion. London: Elsevier Applied Science, 1988.
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Zinovʹev, V. E. Metals at high temperatures: Standard handbook of properties. New York: Hemisphere Publishing Corp., 1990.
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DellaCorte, Christopher. Tribological characteristics of silicon carbide whisker-reinforced alumina at elevated temperatures. [Washington, DC]: National Aeronautics and Space Administration, 1991.
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Zinovʹev, V. E. Handbook of thermophysical properties of metals at high temperatures. New York: Nova Science Publishers, 1996.
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Danzer, Robert. Lebensdauerprognose hochfester metallischer Werkstoffe im Bereich hoher Temperaturen. Berlin: Borntraeger, 1988.
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Morita, Satoshi. Ine no kōon shōgai to taisaku: Tōjuku furyō no shikumi to fusegikata. Tōkyō: Nōsan Gyoson Bunka Kyōkai, 2011.
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Gofman, I͡U M. Ot͡senka rabotosposobnosti metalla ėnergooborudovanii͡a TĖS. Moskva: Ėnergoatomizdat, 1990.
Find full textBook chapters on the topic "Carbides Effect of high temperatures on"
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Li, Yaqiong, Lifeng Zhang, and Zineb Benouahmane. "Effect of Oxidation on Wetting Behavior between Silicon and Silicon Carbide." In 7th International Symposium on High-Temperature Metallurgical Processing, 237–42. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48093-0_30.
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Li, Yaqiong, Lifeng Zhang, and Zineb Benouahmane. "Effect of Oxidation on Wetting Behavior Between Silicon and Silicon Carbide." In 7th International Symposium on High-Temperature Metallurgical Processing, 237–42. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2016. http://dx.doi.org/10.1002/9781119274643.ch30.
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Yucel, Onuralp, Hasan Ozer, Murat Alkan, and Ahmet Turan. "Effects of Functional Additives on the SHS of Boron Carbide." In 6th International Symposium on High-Temperature Metallurgical Processing, 61–66. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2015. http://dx.doi.org/10.1002/9781119093381.ch8.
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Yucel, Onuralp, Hasan Ozer, Murat Alkan, and Ahmet Turan. "Effects of Functional Additives on the SHS of Boron Carbide." In 6th International Symposium on High-Temperature Metallurgical Processing, 61–66. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-48217-0_8.
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Cao, Jian Xin, Fei Liu, Qian Lin, Yu Zhang, Yong Gang Dong, and Ling Ke Zeng. "Effect of Calcination Temperature on Mineral Composition of Carbide Slag, Lime Activity and Synthesized Xonotlite." In High-Performance Ceramics V, 1545–47. Stafa: Trans Tech Publications Ltd., 2008. http://dx.doi.org/10.4028/0-87849-473-1.1545.
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Tyler, Christopher J. "The effect of high ambient temperatures on exercise performance." In Maximising Performance in Hot Environments, 64–81. New York, NY: Routledge, 2019.: Routledge, 2019. http://dx.doi.org/10.4324/9781351111553-4.
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Tyler, Christopher J. "The effect of high ambient temperatures on cognitive function." In Maximising Performance in Hot Environments, 82–101. New York, NY: Routledge, 2019.: Routledge, 2019. http://dx.doi.org/10.4324/9781351111553-5.
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Kinoshita, Akimasa, Makoto Katou, Miwa Kawasaki, Kazutoshi Kojima, Kenji Fukuda, Kazuo Arai, Fukuyoshi Morigasa, Tomoyoshi Endou, Takuo Isii, and Teruyuki Yashima. "Effect of Surface Orientation and Off-Angle on Surface Roughness and Electrical Properties of p-Type Impurity Implanted 4H-SiC Substrate after High Temperature Annealing." In Silicon Carbide and Related Materials 2005, 835–38. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-425-1.835.
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Weber, P. K. H., H. D. Menningmann, and J. M. Greenberg. "Effect of High-Vacuum, Deep Temperatures and VUV Irradiation on Bacterial Spores." In Terrestrial Space Radiation and Its Biological Effects, 383–91. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-1567-4_29.
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Nomura, K., Z. Homonnay, G. Juhász, A. Vértes, H. Donen, and Ts Sawada. "Mössbauer Study of (Sr,Ca)(Fe,Co)O3−δ Applied to CO2 Absorption at High Temperatures." In Industrial Applications of the Mössbauer Effect, 297–305. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0299-8_31.
Full textConference papers on the topic "Carbides Effect of high temperatures on"
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Uusitalo, M., P. Vuoristo, T. Mäntylä, L.-M. Berger, and R. Backman. "The Effect of Chlorine on Degradation Mechanisms of Thermal Sprayed Coatings at Elevated Temperatures." In ITSC2003, edited by Basil R. Marple and Christian Moreau. ASM International, 2003. http://dx.doi.org/10.31399/asm.cp.itsc2003p0485.
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Abstract The significance of biofuels and the other chlorine-containing fuels in energy production is in strong increase. Serious erosion-corrosion problems in boilers combusting fuels with high chlorine-content have been detected frequently. A series of erosion-corrosion and corrosion tests were performed on thermal sprayed coatings and coating precursors in chlorine-containing environments in order to evaluate possibilities to utilize thermal sprayed coatings for erosion-corrosion protection in boilers combusting chlorine-containing fuels. A series of hot erosion and erosion-corrosion tests were performed on thermal sprayed coatings at elevated temperatures with and without chlorine. Carbide-containing HVOF coatings performed well in hot erosion tests, but they were completely destroyed in the presence of chlorine due to rapid oxidation of carbides. Metallic HVOF coatings with high chromium content performed well in both conditions. Iron-based arc-sprayed coatings with unhomogeneous microstructure suffered more hot erosion and erosion-corrosion damages than metallic HVOF coatings. The E-C (erosion-corrosion) resistance of carbide-containing coatings in the presence of chlorides was worse than expected. A series of oxidation tests were performed on various carbides in order to elucidate the effect of chlorine on high temperature oxidation behavior of carbides. TGA and isothermal oxidation tests proved that gaseous chlorine-containing species and also solid chlorides have a detrimental effect on oxidation resistance of tested carbides.
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Trindade Rosário Pessanha, Ítalo, Sara Fidelis Silva, Vithoria Réggia Gomes Pessanha, Michel Picanço Oliveira, Márcia Giardinieri de Azevedo, and Bárbara Ferreira de Oliveira. "Spark plasma sintering of cemented carbide WC-10% wt. AISI 304L cemented carbides using nanopowders." In 7th International Congress on Scientific Knowledge. Exatas & Engenharias, 2021. http://dx.doi.org/10.25242/885x331120212333.
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Tungsten carbide (WC) cemented carbides with alternative binders to cobalt have been researched due to the low availability, high cost and toxicity of this element. Promising results have been found for the use of austenitic stainless steel microparticles of AISI 304L as binders in cemented carbides, since they have good wettability with WC and produce materials with mechanical properties and corrosion resistance comparable to cemented from the WC-Co system. In this context, this work aims to produce cemented carbides using a combination of WC nanoparticles and 10% AISI 304L stainless steel. The production of these composites will be carried out via sintering by spark plasma sintering at different temperatures. Density, densification, microstructure, hardness and fracture toughness of the samples will be analysed. It is expected to show the benefits of using nanoparticles to produce carbide, in addition to the effects of temperature in the sintering process. Finally, a comparison will be made with data found in the literature on cemented carbides from the WC-Co system that will indicate the possibility of replacing AISI 304L as a binder of these materials.
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Schrock, David, Xin Wang, and Patrick Kwon. "An Analysis of the Wear of Tungsten Carbide and Polycrystalline Diamond Inserts Turning Ti-6Al-4V." In ASME 2011 International Manufacturing Science and Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/msec2011-50175.
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Dry turning experiments on Ti-6Al-4V were conducted using two grades (finer and coarser) of carbides and polycrystalline diamond (PCD) inserts to study tool wear. Despite of minor compositional difference between two carbide grades, both grades contain 6% Co. Crater wear and flank wear were measured using Confocal Laser Scanning Microscopy (CLSM). Three dimensional rake surface topographies were reconstructed from the CLSM data and wear profiles were extracted. Finite Element Analysis (FEA) was conducted to study the effects of cutting conditions and thermal properties on rake face temperature. Flank wear on the carbide tools indicated that the inserts with the finer grain size exhibited smaller flank wear than the insert of the coarser grain size. This was attributed to reduced abrasive wear in the finer grained inserts as a result of a higher hardness. The carbide grade with a coarser grain size had an enhanced ability to resist crater wear, likely from lower rake face temperatures and the differences in the compositions. It is known that coarser grain carbides have a higher thermal conductivity resulting from increased grain contiguity. FEA was used to study the temperature difference between the two grain-sizes and the effect of thermal conductivity on temperature gradients. Tool wear of the PCD inserts was also studied. The PCD tools showed significant adhesive wear at the 200sfm cutting speed, transitioning to crater wear at 400sfm. With a high thermal conductivity, it is possible that rake face temperatures were low enough to alter the wear mechanism. FEA supports this hypothesis, as the maximum rake face temperature for the PCD inserts were only around 900°C at 200sfm.
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Shimamura, Junji, Shusaku Ota, Tomoyuki Yokota, and Ryuji Muraoka. "Effect of Initial Bainite Microstructure on Tensile Properties After Long-Term Exposure at Elevated Temperature." In 2018 12th International Pipeline Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/ipc2018-78551.
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In the oil sand production field in Canada, steel pipes are used for injecting steam into the sands. Pipes for steam distribution are subjected to high operating temperature such as 350 degrees C for a long time. In this study, in order to insure the reliability of high strength pipe for steam distribution, long-term heating tests were conducted for X80 grade UOE pipe. To simulate the long-term operation at 350 degrees C for 40 years, accelerated tests were conducted at 400 degrees C for up to 4400 hours. The effect of initial bainite microstructure on tensile properties after long-term heat treatment was investigated by using two kinds of steel pipes with different bainite microstructure. One is accelerated cooling (ACC) type, and the other is heating on-line process (HOP) type just after accelerated cooling in plate manufacturing process. It was revealed that strength decrease in ACC type steels produced by only accelerated cooling was mainly governed by decomposition of hard phase MA (Martensite-Austenite constituent) and recovery of dislocations. On the other hand, HOP type steels had small amount of MA and nanometer-sized carbides by applying HOP after accelerated cooling. The HOP type steels had almost the same initial strength in spite of small amount of MA. Fine niobium carbides gave enough precipitation strengthening. Formation of fine niobium carbides was promoted by the addition of niobium. The precipitates were stable after long-term heat treatment at 400 degrees C. It is confirmed that the fine niobium carbides in HOP type steels remained even after long-term heat treatment. The suppression of initial MA also lead to minimize the strength decrease by MA decomposition. Therefore, HOP type steels tend to have higher resistance to the strength decrease after long-term heat treatment.
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Wang, Yian, Guoshan Xie, Zheng Zhang, Xiaolong Qian, Yufeng Zhou, and Jing Li. "Effect of Carbide Content on Temper Embrittlement of 2.25Cr1Mo Steel." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63289.
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Temper embrittlement is a common damage mechanism of pressure vessels in the chemical and petrochemical industry serviced in high temperature, which results in the reduction of roughness due to metallurgical change in some low alloy steels. Pressure vessels that are temper embrittled may be susceptible to brittle fracture under certain operating conditions which cause high stress by thermal gradients, e.g., during start-up and shutdown. 2.25Cr1-Mo steel is widely used to make hydrogenation reactor due to its superior combination of high mechanical strength, good weldability, excellent high temperature hydrogen attack (HTHA) and oxidation-resistance. However, 2.25Cr-1Mo steel is particularly susceptible to temper embrittlement. In this paper, the effect of carbide on temper embrittlement of 2.25Cr-1Mo steel was investigated. Mechanical properties and the ductile-brittle transition temperature (DBTT) of 2.25Cr-1Mo steel were measured by tensile test and impact test. The tests were performed at two positions (base metal and weld metal) and three states (original, step cooling treated and in-service for a hundred thousand hours). The content and distribution of carbides were analyzed by scanning electron microscope (SEM). The content of Cr and Mo elements in carbide was measured by energy dispersive X-ray analysis (EDS). The results showed that the embrittlement could increase the strength and reduce the plasticity. Higher carbide contents appear to be responsible for the higher DBTT. The in-service 2.25Cr-1Mo steel showed the highest DBTT and carbide content, followed by step cooling treated 2.25Cr-1Mo steel, while the as-received 2.25Cr-1Mo steel has the minimum DBTT and carbide content. At the same time, the Cr and Mo contents in carbide increased with the increasing of DBTT. It is well known that the specimen analyzed by SEM is very small in size, sampling SEM specimen is convenient and nondestructive to pressure vessel. Therefore, the relationship between DBTT and the content of carbide offers a feasible nondestructive method for quantitative measuring the temper embrittlement of 2.25Cr-1Mo steel pressure vessel.
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Tomita, T., K. Okita, Y. Taratani, and Y. Harada. "Improvement of Wear Property of NbC/High Cr-High Ni Overlay Alloy Coating Formed by Plasma Transferred Arc Welding Process." In ITSC 1998, edited by Christian Coddet. ASM International, 1998. http://dx.doi.org/10.31399/asm.cp.itsc1998p0253.
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Abstract This paper presents the results of a study showing how isothermal aging affects the wear properties of Cr-Ni overlay alloy coatings with dispersed NbC particles. High Cr-high Ni coatings, with and without niobium carbides, were deposited on mild steel substrates via plasma transferred arc welding then age-hardened at temperatures from 773 to 1023 K. The precipitation behavior and wear properties of the coating samples were examined using Vickers hardness testing, SEM, TEM, EDX, XRD, and Ohgoshi wear testing. The results showed that isothermal aging significantly improved the hardness and wear resistance of the NbC-dispersed alloy but had little effect on the NbC-free samples. The difference in precipitation behaviors is probably due to the presence of niobium atoms in the alloy matrix, resulting in a continuous precipitation of α' phase.
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Liu, Kui, Xianchao Hao, Ming Gao, Shuo Li, Yiyi Li, and Bofang Wang. "Effect of N Content on Mechanical Properties and Microstructure of Alloy 690." In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75195.
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The microstructures and mechanical properties of nitrogen bearing Alloy 690 have been systematically investigated. Alloy ingots with different N addition, range from 38 to 330wt.ppm, were melted using vacuum induction melting (VIM) plus electro-slag re-melting (ESR) double processing techniques. The forged and hot rolled different N content bars were solid solution treated between 1010°C and 1080°C, thermally treated at 715°C for different state mechanical property testing and microstructure study. Microstructure analysis indicated that nitrogen addition to Alloy 690 can effectively refine the solution treated austenite grains. This may be associated with titanium nitrides pinning the grain boundaries and hindering the grain growth during solid solution treatment. More nitrides, which are identified as TiN, were found on the grain boundaries and in the inside of austenite grains with increasing N contents of the alloy. The carbide precipitation at 715°C showed significant difference identified by SEM. At the level of 38, 100 and 220wt.ppm N, the chromium carbide Cr23C6 distribution on the grain boundaries appeared to be semi-continuous; when the N content reached 330wt.ppm, only few discrete type of carbides were observed. The tension testing results at room temperature of different N content alloys proved that both the ultimate tensile strength (UTS) and the yield strength (YS) enhanced about 50MPa when N content was raised from 38 to 330wt.ppm in this alloy; while the corresponding elongation (EL) and reduction in area (RA) adversely dropped about 5%. Room temperature hardness rose with increasing N content, well matched tensile strength. High temperature tension testing results at the range of 900∼1250°C showed that a severely hot ductility dip, representing by the values of the reduction in area (RA), existed in 300wt.ppm and 100wt.ppm nitrogen containing alloys at the lower end temperature range of 950∼1100°C. However, such ductility dip could be improved when the N content was at 220wt.ppm, and completely eliminated at 38wt.ppm N content. At the higher end temperature rang of 1150∼1250°C, the ductility of all 4 nitrogen bearing alloys did not show significant difference, even though the hot ductility of minimum 38wt.ppm N samples was preferable. Nitrogen content did not affect high temperature strength; the UTS values nearly had no change at the same testing temperature with different nitrogen bearing alloys. The carbide precipitation difference of the thermally treated alloy, induced by N addition, may affect Alloy 690 corrosion properties, which needs to be studied in future. The mechanical properties variation both at room temperature and high temperatures of different nitrogen bearing alloys in this study will be certainly beneficial to determine the practical processing routes of Alloy 690.
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Matikainen, V., J. Lagerbom, K. Kaunisto, V. Heino, K. Bobzin, W. Wietheger, E. Burbaum, et al. "Wear Resistant Nano-Carbide WC-CoCr Coating by Novel Powder Manufacturing Method." In ITSC2022. DVS Media GmbH, 2022. http://dx.doi.org/10.31399/asm.cp.itsc2022p0559.
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Abstract Surface quality lifetime and wear resistance of protective coatings can be improved by decreasing carbide grain size from submicron to nanoscale. In this study, experimental WC-CoCr powders were manufactured via novel powder manufacturing approach using water-soluble raw materials. Produced powders were sprayed with the High-Velocity Air-Fuel (HVAF) spray process to control the particle temperature and to avoid in-flight decomposition of the nanocarbides. As a result, dense and wear resistant coatings with nanosized carbides were produced. Reference coatings were sprayed using commercial sub-micron WC-CoCr powder to compare the properties of the experimental coatings to the current state-of-the-art. Phase composition and microstructural characterization of the coatings were carried out with X-ray diffraction and electron microscopy, respectively. Mechanical properties were studied by using microhardness tester, as well as rubber wheel abrasion and cavitation erosion wear tests. The wear surfaces were characterized after the abrasion and cavitation erosion tests to understand the effect of nano-carbides on degradation mechanisms. Coatings with the nanosized carbides in the structure showed excellent mechanical properties in wear testing, and even outperformed reference coatings in cavitation erosion test. Based on the obtained results, these novel nano-carbide coatings are promising alternatives for demanding applications in which better surface quality lifetime is vital.
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Medyanik, S. N., and N. Vlahopoulos. "Atomistic Simulation Studies of the Effects of Defects on Thermal Properties of Ultra High Temperature Ceramics." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65389.
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Due to the harsh environments created by high speeds, significant new demands are placed on materials used for constructing hypersonic vehicles. Ultra high temperature ceramics (UHTCs) like carbides and borides exhibit unique thermal properties, such as very high melting points and good thermal conductivities. These properties make the ceramic materials good candidates for applications like Thermal Protection Systems (TPS) of the hypersonic vehicles. However, thermal properties of UHTCs may be very sensitive to microstructures of the materials. Thus, atomic scale defects may impact certain thermal properties, such as thermal conductivity. The effects of such small defects may be properly studied only through atomistic simulation methods, such as molecular dynamics (MD). Previously, atomistic simulation studies have been performed for the effects of point defects on thermal properties in silicon carbide (SiC). In addition, atomistic simulations have been applied to assess thermal conductivity in zirconium diboride (ZrB2) for perfect crystals and polycrystals. However, to our knowledge, no studies of the effects of point defects have been performed for zirconium diboride. This paper applies atomistic simulations to assess the impact of point defects on thermal conductivity in ZrB2 perfect crystals. Recently derived interatomic potential for ZrB2 along with LAMMPS molecular simulation package and MedeA software environment are employed in this effort. Phonon part of the thermal conductivity is calculated using Green-Kubo method. Calculations for a perfect crystal are conducted first and the results are compared to experimental data available from the literature. Then, several types of point defects are considered (vacancies, substitutions, and interstitials) and their impact on the phonon conductivity is evaluated. It is found that even a small concentration of point defects may have substantial effect and result in a reduction in the thermal conductivity values by almost an order of magnitude. The obtained results are in good qualitative agreement with previous studies conducted for silicon carbide. The methodology which is utilized in this work, the modeling procedure, and the obtained results are discussed in this paper.
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Zhao, Yanping, Jianming Gong, and Yong Jiang. "The Effect of Carbon Diffusion on Creep Behaviours for a Dissimilar Joint Between P91 and 12Cr1MoV Steels." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63108.
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Dissimilar joints have been widely used in many applications, especially for steam piping in the superheater and reheater of power plants. However, these dissimilar metal welds tend to fail less than half of their design life, and carbon diffusion is the main cause of the premature failure. Dissimilar joints operated at high temperature or after post-weld heat treatment (PWHT) exhibit carbon-enriched zone (CEZ) in the high alloy part and carbon-depleted zone (CDZ) in the low alloy part, causing by the chemical potential gradients across the weld interface. The carbides dissolute in the low alloy part while precipitate in the high alloy part. At the same time, a consequent of strength gradients are generated between the CEZ and CDE. The CDZ results in a loss of creep strength due to the carbides dissolution while an increase of strength due to the carbides precipitation. In this work, welding consumable of GTR-2CM was used to join P91 and 12Cr1MoV metals together. The stable phases and carbon activities of these metals are calculated by THERMO-CALC software. Carbon diffusion between P91/GTR-2CM/12Cr1MoV dissimilar joint after aging at 550 °C for varying time are predicted by employing dispersed multiphase model in DICTRA software. Volume fractions of carbides varying with distance from both sides of the weld interfaces were also investigated, showing that the formation of CDZs and CEZs is related to the dissolution and precipitation of M23C6 and M7C3 carbides. The dissolution and coarsening of M7C3 and M23C6 particles in the CDZ and CEZ were also modelled by DICTRA software. The creep properties of base metals, weld metal and the dissimilar joint were investigated at 550 °C. The stress dependence of minimum creep rate and rupture life obeyed the Norton’s power law, and the stress exponents can be used to identify the creep mechanism. Monkman-Grant (MG) relations were also used to study the creep rupture data. The simulation results of carbon diffusion can be used to study the creep properties of CDZ and CEZ for the P91/GTR-2CM/12Cr1MoV dissimilar joint. The threshold stress concept can be incorporated into the analysis of creep power law. The magnitudes of threshold stress within CEZ and CDZ can be calculated according to the volume fraction and average diameter of carbides from carbon diffusion.
Reports on the topic "Carbides Effect of high temperatures on"
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Bronson, Arturo, and Vinod Kumar. A Computational-Experimental Study of Plasma Processing of Carbides at High Temperatures. Office of Scientific and Technical Information (OSTI), February 2016. http://dx.doi.org/10.2172/1243051.
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Faik, Aygyun, Daniela Stanoeva, and Maya Velitchkova. High Light Enhances the Inhibitory Effect of Suboptimal Temperatures on the Oxygen Evolving Reactions in Arabidopsis thaliana. "Prof. Marin Drinov" Publishing House of Bulgarian Academy of Sciences, February 2018. http://dx.doi.org/10.7546/crabs.2018.02.08.
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Faik, Aygyun, Daniela Stanoeva, and Maya Velitchkova. High Light Enhances the Inhibitory Effect of Suboptimal Temperatures on the Oxygen Evolving Reactions in Arabidopsis thaliana. "Prof. Marin Drinov" Publishing House of Bulgarian Academy of Sciences, February 2018. http://dx.doi.org/10.7546/grabs2018.2.08.
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Browdy, Craig, and Esther Lubzens. Cryopreservation of Penaeid Shrimp Embryos: Development of a Germplasm Cryo-Bank for Preservation of High Health and Genetically Improved Stocks. United States Department of Agriculture, August 2002. http://dx.doi.org/10.32747/2002.7695849.bard.
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The objectives of the project were to develop a successful protocol for cryopreservation of penaeid germ plasm in order to preserve a pathogen-free broodstock nucleus for commercial exploitation of marine shrimp in aquaculture. The critical parameters to be characterized in the project were: 1. Determination of chill sensitivity and chill tolerant embryonic stages, including a full description and time course study of embryonic developmental stages. 2. Development of protocols for loading and removal of cryoprotectant agents (CPAs) from embryos; determination of optimal concentrations and duration of loading. 3. Characterization of the toxicity of the selected CP As and 4. Establishing optimal cooling and thawing procedures. Studies were performed on two penaeid species: Litopenaeus vannamei (in the USA) and P. semisulcatus (in Israel). The effect of incubation temperature on embryonic development rate and hatching success was studied in L. vannamei, showing that spawns maybe maintained at temperatures ranging from 24°C to 30°C, without compromising hatchability. Embryonic development extends from 12 hr to 19 hr at 30°C and 24°C, respectively. Studies showed that advanced embryonic developmental stages were chill tolerant in the two studied species, but P. semisulcatus could better endure lower temperatures than L. vannamei. A large number of experiments were performed to determine the optimal CP As, their concentration and duration of loading. Permeating (e.g. glycerol, methanol, DMSO, 1,2- propanediol, ethylene glycol, glucose) and non-permeating CPAs (sucrose, PVP, polyethylene glycol) were tested and several combinations of permeating and non-permeating CP As, on fertilized eggs (embryos), nauplii and protozoeae. In general, nauplii tolerated higher CPA concentrations than eggs and nauplii were also more permeable to radiolabeled methanol. Chlorine treatment intended to remove the chitinous envelop from eggs, did not increase dramatically the permeation of radiolabled methanol into eggs. Cooling eggs, nauplii or protozoeae to cryogenic temperatures, by either vitrification or slow cooling protocols, did not result in full survival of thawed samples, despite exhaustive attempts testing various protocols and CP As. Results seemed more encouraging in freezing of nauplii in comparison to eggs or protozoeae. Successful preliminary results in cryopreservation of spermatozoa of P. vannamei, will facilitate preservation of genetic specific to some extent.
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Chen, Junping, Zach Adam, and Arie Admon. The Role of FtsH11 Protease in Chloroplast Biogenesis and Maintenance at Elevated Temperatures in Model and Crop Plants. United States Department of Agriculture, May 2013. http://dx.doi.org/10.32747/2013.7699845.bard.
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specific objectives of this proposal were to: 1) determine the location, topology, and oligomerization of FtsH11 protease; 2) identify the substrate/s of FtsH11 and the downstream components involved in maintaining thermostability of chloroplasts; 3) identify new elements involved in FtsH11 protease regulatory network related to HT adaptation processes in chloroplast; 4) Study the role of FtsH11 homologs from crop species in HT tolerance. Background to the topic: HT-tolerant varieties that maintain high photosynthetic efficiency at HT, and cope better with daily and seasonal temperature fluctuations are in great need to alleviate the effect of global warming on food production. Photosynthesis is a very complex process requiring accurate coordination of many complex systems and constant adjustments to the changing environments. Proteolytic activities mediated by various proteases in chloroplast are essential part of this process and critical for maintaining normal chloroplast functions under HT. However, little is known about mechanisms that contribute to adaptation of photosynthetic processes to HT. Our study has shown that a chloroplast-targeted Arabidopsis FtsH11 protease plays an essential and specific role in maintaining thermostability of thylakoids and normal photosynthesis at moderate HT. We hypothesized that FtsH11 homologs recently identified in other plant species might have roles similarly to that of AtFtsH1. Thus, dissecting the underlying mechanisms of FtsH11 in the adaptation mechanisms in chloroplasts to HT stress and other elements involved will aid our effort to produce more agricultural products in less favorable environments. Major conclusions, solutions, achievements - Identified the chloroplast inner envelope membrane localization of FtsH11. - Revealed a specific association of FtsH11 with the a and b subunits of CPN60. - Identified the involvement of ARC6, a protein coordinates chloroplast division machineries in plants, in FtsH11 mediated HT adaptation process in chloroplast. -Reveal possible association of a polyribonucleotide nucleotidyltransferase (cpPNPase), coded by At3G03710, with FtsH11 mediated HT adaptation process in chloroplast. - Mapped 4 additional loci in FtsH11 mediated HT adaptation network in chloroplast. - Demonstrated importance of the proteolytic activity of FtsH11 for thermotolerance, in addition to the ATPase activity. - Demonstrated a conserved role of plant FtsH11 proteases in chloroplast biogenesis and in maintaining structural and functional thermostability of chloroplast at elevated temperatures. Implications, both scientific and agricultural:Three different components interacting with FtsH11 were identified during the course of this study. At present, it is not known whether these proteins are directly involved in FtsH11mediated thermotolerance network in chloroplast and/or how these elements are interrelated. Studies aiming to connect the dot among biological functions of these networks are underway in both labs. Nevertheless, in bacteria where it was first studied, FtsH functions in heat shock response by regulating transcription level of σ32, a heat chock factor regulates HSPsexpression. FtsH also involves in control of biosynthesis of membrane components and quality control of membrane proteins etc. In plants, both Arc 6 and CPN60 identified in this study are essential in chloroplast division and developments as mutation of either one impairs chloroplast division in Arabidopsis. The facts that we have found the specific association of both α and β CPN60 with FtsH11 protein biochemically, the suppression/ enhancement of ftsh11 thermosensitive phenotype by arc6 /pnp allele genetically, implicate inter-connection of these networks via FtsH11 mediated network(s) in regulating the dynamic adaptation processes of chloroplast to temperature increases at transcriptional, translational and post-translational levels. The conserved role of FtsH11 proteases in maintaining thermostability of chloroplast at HT demonstrated here provides a foundation for improving crop photosynthetic performance at high temperatures.
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Chiel, Elad, and Christopher J. Geden. Development of sustainable fly management tools in an era of global warming. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7598161.bard.
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House flies (Muscadomestica) are global pests of animal agriculture, causing major annoyance, carrying pathogens among production facilities and humans and thus have profound impacts on animal comfort and productivity. Successful fly control requires an integrated pest management (IPM) approach that includes elements of manure management, mass trapping, biological control, and selective insecticide use. Insecticidal control of house flies has become increasingly difficult due to the rapidity with which resistance develops, even to new active ingredients. Global climate change poses additional challenges, as the efficacy of natural enemies is uncertain under the higher temperatures that are predicted to become more commonplace in the future. The two major objectives of this research project were: 1) to develop a cost-effective autodissemination application method of Pyriproxifen (PPF), an insect growth regulator, for controlling house flies; 2) to study the effect of increasing temperatures on the interactions between house flies and their principal natural enemies. First, we collected several wild house fly populations in both countries and established that most of them are susceptible to PPF, although one population in each country showed initial signs of PPF-resistance. An important finding is that the efficacy of PPF is substantially reduced when applied in cows’ manure. We also found that PPF is compatible with several common species of parasitoids that attack the house fly, thus PPF can be used in IPM programs. Next, we tried to develop “baited stations” in which house flies will collect PPF on their bodies and then deliver and deposit it in their oviposition sites (= autodissemination). The concept showed potential in lab experiments and in outdoor cages trials, but under field conditions the station models we tested were not effective enough. We thus tested a somewhat different approach – to actively release a small proportion of PPF-treated flies. This approach showed positive results in laboratory experiments and awaits further field experiments. On the second topic, we performed two experimental sets: 1) we collected house flies and their parasitoids from hot temperature and mild temperature areas in both countries and, by measuring some fitness parameters we tested whether the ones collected from hot areas are better adapted to BARD Report - Project 4701 Page 2 of 16 heat. The results showed very little differences between the populations, both of flies and parasitoids. 2) A “fast evolution” experiment, in which we reared house flies for 20 generations under increasing temperatures. Also here, we found no evidence for heat adaptation. In summary, pyriproxyfen proved to be a highly effective insect growth regulator for house flies that is compatible with it’s natural enemies. Although our autodissemination stations yielded disappointing results, we documented the proportion of flies in a population that must be exposed to PPF to achieve effective fly control. Both the flies and their principal parasitoids show no evidence for local adaptation to high temperatures. This is an encouraging finding for biological control, as our hypothesis was that the fly would be adapting faster to high temperatures than the parasitoids. BARD Report - Project 4701 Page 3 of 16
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Samach, Alon, Douglas Cook, and Jaime Kigel. Molecular mechanisms of plant reproductive adaptation to aridity gradients. United States Department of Agriculture, January 2008. http://dx.doi.org/10.32747/2008.7696513.bard.
Full textAbstract:
Annual plants have developed a range of different mechanisms to avoid flowering (exposure of reproductive organs to the environment) under adverse environmental conditions. Seasonal environmental events such as gradual changes in day length and temperature affect the timing of transition to flowering in many annual and perennial plants. Research in Arabidopsis and additional species suggest that some environmental signals converge on transcriptional regulation of common floral integrators such as FLOWERING LOCUS T (FT). Here we studied environmental induction of flowering in the model legume Medicago truncatula. Similarly to Arabidopsis, the transition to flowering in M. truncatula is hastened by long photoperiods and long periods of vernalization (4°C for 2-3 weeks). Ecotypes collected in Israel retain a vernalization response even though winter temperatures are way above 4°C. Here we show that this species is also highly responsive (flowers earlier) to mild ambient temperatures up to 19°C simulating winter conditions in its natural habitat. Physiological experiments allowed us to time the transition to flowering due to low temperatures, and to compare it to vernalization. We have made use of natural variation, and induced mutants to identify key genes involved in this process, and we provide here data suggesting that an FT gene in M.truncatula is transcriptionally regulated by different environmental cues. Flowering time was found to be correlated with MtFTA and MtFTB expression levels. Mutation in the MtFTA gene showed a late flowering phenotype, while over-expressing MtFTA in Arabidopsis complemented the ft- phenotype. We found that combination of 4°C and 12°C resulted in a synergistic increase in MtFTB expression, while combining 4°C and long photoperiods caused a synergistic increase in MtFTA expression. These results suggest that the two vernalization temperatures work through distinct mechanisms. The early flowering kalil mutant expressed higher levels of MtFTA and not MtFTB suggesting that the KALIL protein represses MtFTA specifically. The desert ecotype Sde Boker flowers earlier in response to short treatments of 8-12oc vernalization and expresses higher levels of MtFTA. This suggests a possible mechanism this desert ecotype developed to flower as fast as possible and finish its growth cycle before the dry period. MtFTA and FT expression are induced by common environmental cues in each species, and expression is repressed under short days. Replacing FT with the MtFTA gene (including regulatory elements) caused high MtFTA expression and early flowering under short days suggesting that the mechanism used to repress flowering under short days has diversified between the two species.The circadian regulated gene, GIGANTEA (GI) encodes a unique protein in Arabidopsis that is involved in flowering mechanism. In this research we characterized how the expression of the M.truncatula GI ortholog is regulated by light and temperature in comparison to its regulation in Arabidopsis. In Arabidopsis GI was found to be involved in temperature compensation to the clock. In addition, GI was found to be involved in mediating the effect of temperature on flowering time. We tested the influence of cold temperature on the MtGI gene in M.truncatula and found correlation between MtGI levels and extended periods of 12°C treatment. MtGI elevation that was found mostly after plants were removed from the cold influence preceded the induction of MtFT expression. This data suggests that MtGI might be involved in 12°C cold perception with respect to flowering in M.truncatula. GI seems to integrate diverse environmental inputs and translates them to the proper physiological and developmental outputs, acting through several different pathways. These research enabled to correlate between temperature and circadian clock in M.truncatula and achieved a better understanding of the flowering mechanism of this species.
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Bryant, C. A., S. A. Wilks, and C. W. Keevil. Survival of SARS-CoV-2 on the surfaces of food and food packaging materials. Food Standards Agency, November 2022. http://dx.doi.org/10.46756/sci.fsa.kww583.
Full textAbstract:
COVID-19, caused by the SARS-CoV-2 virus, was first reported in China in December 2019. The virus has spread rapidly around the world and is currently responsible for 500 million reported cases and over 6.4 million deaths. A risk assessment published by the Foods Standards Agency (FSA) in 2020 (Opens in a new window) concluded that it was very unlikely that you could catch coronavirus via food. This assessment included the worst-case assumption that, if food became contaminated during production, no significant inactivation of virus would occur before consumption. However, the rate of inactivation of virus on products sold at various temperatures was identified as a key uncertainty, because if inactivation does occur more rapidly in some situations, then a lower risk may be more appropriate. This project was commissioned to measure the rate of inactivation of virus on the surface of various types of food and food packaging, reducing that uncertainty. The results will be used to consider whether the assumption currently made in the risk assessment remains appropriate for food kept at a range of temperatures, or whether a lower risk is more appropriate for some. We conducted a laboratory-based study, artificially contaminating infectious SARS-CoV-2 virus onto the surfaces of foods and food packaging. We measured how the amount of infectious virus present on those surfaces declined over time, at a range of temperatures and relative humidity levels, reflecting typical storage conditions. We tested broccoli, peppers, apple, raspberry, cheddar cheese, sliced ham, olives, brine from the olives, white and brown bread crusts, croissants and pain au chocolat. The foods tested were selected as they are commonly sold loose on supermarket shelves or uncovered at deli counters or market stalls, they may be difficult to wash, and they are often consumed without any further processing i.e. cooking. The food packaging materials tested were polyethylene terephthalate (PET1) trays and bottles; aluminium cans and composite drinks cartons. These were selected as they are the most commonly used food packaging materials or consumption of the product may involve direct mouth contact with the packaging. Results showed that virus survival varied depending on the foods and food packaging examined. In several cases, infectious virus was detected for several hours and in some cases for several days, under some conditions tested. For a highly infectious agent such as SARS-CoV-2, which is thought to be transmissible by touching contaminated surfaces and then the face, this confirmation is significant. For most foods tested there was a significant drop in levels of virus contamination over the first 24 hours. However, for cheddar cheese and sliced ham, stored in refrigerated conditions and a range of relative humidity, the virus levels remained high up to a week later, when the testing period was stopped. Both cheddar cheese and sliced ham have high moisture, protein and saturated fat content, possibly offering protection to the virus. When apples and olives were tested, the virus was inactivated to the limit of detection very quickly, within an hour, when the first time point was measured. We suggest that chemicals, such as flavonoids, present in the skin of apples and olives inactivate the virus. The rate of viral decrease was rapid, within a few hours, for croissants and pain au chocolat. These pastries are both coated with a liquid egg wash, which may have an inhibitory effect on the virus. Food packaging materials tested had variable virus survival. For all food packaging, there was a significant drop in levels of virus contamination over the first 24 hours, in all relative humidity conditions and at both 6°C and 21°C; these included PET1 bottles and trays, aluminium cans and composite drinks cartons.
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Droby, Samir, Joseph W. Eckert, Shulamit Manulis, and Rajesh K. Mehra. Ecology, Population Dynamics and Genetic Diversity of Epiphytic Yeast Antagonists of Postharvest Diseases of Fruits. United States Department of Agriculture, October 1994. http://dx.doi.org/10.32747/1994.7568777.bard.
Full textAbstract:
One of the emerging technologies is the use of microbial agents for the control of postharvest diseases of fruits and vegetables. A number of antagonistic microorganisms have been discovered which have the potential to effectively control postharvest diseases. Some of this technology has been patented and commercial products such as AspireTM (Ecogen Corporatin, Langhorne, PA, USA), Biosave 10TM and Biosave 11TM (Ecoscience Inc., Worchester, MA, USA) have been registered for commercial use. The principal investigator of this project was involved in developing the yeast-based biofungicide-AspireTM and testing its efficacy under commercial conditions. This research project was initiated to fill the gap between the knowledge available on development and commercial implementation of yeast biocontrol agents and basic understanding of various aspects related to introducing yeast antagonists to fruit surfaces, along with verification of population genetics. The main objectives of this study were: Study ecology, population dynamics and genetic diversity of the yeast antagonists Candida guilliermondii, C. oleophila, and Debaryomyces hansenii, and study the effect of preharvest application of the yeast antagonist C. oleophila naturally occurring epiphytic microbial population and on the development of postharvest diseases of citrus fruit during storage. Our findings, which were detailed in several publications, have shown that an epiphytic yeast population of grapefruit able to grow under high osmotic conditions and a wide range of temperatures was isolated and characterized for its biocontrol activity against green mold decay caused by Penicillium digitatum. Techniques based on random amplified polymorphic DNA (RAPD) and arbitrary primed polymerase chain reaction (ap-PCR), as well as homologies between sequences of the rDNA internal transcribed spacers (ITS) and 5.8S gene, were used to characterize the composition of the yeast population and to determine the genetic relationship among predominant yeast species. Epiphytic yeasts exhibiting the highest biocontrol activity against P. digitatum on grapefruit were identified as Candida guilliermondii, C. oleophila, C. sake, and Debaryomyces hansenii, while C. guilliermondii was the most predominant species. RAPD and ap-PCR analysis of the osmotolerant yeast population showed two different, major groups. The sequences of the ITS regions and the 5.8S gene of the yeast isolates, previously identified as belonging to different species, were found to be identical. Following the need to develop a genetically marked strain of the yeast C. oleophila, to be used in population dynamics studies, a transformation system for the yeast was developed. Histidine auxotrophy of C. oloephila produced using ethyl methanesulfonate were transformed with plasmids containing HIS3, HIS4 and HIS5 genes from Saccharomyces cerevisiae. In one mutant histidin auxotrophy was complemented by the HIS5 gene of S. cerevisiae is functionally homologous to the HIS5 gene in V. oleophila. Southern blot analysis showed that the plasmid containing the S. cerevisiae HIS5 gene was integrated at a different location every C. oleophila HIS+ transformant. There were no detectable physiological differences between C. oleophila strain I-182 and the transformants. The biological control ability of C. oleophila was not affected by the transformation. A genetically marked (with b-glucuronidase gene) transformant of C. oleophila colonized wounds on orange fruits and its population increased under field conditions. Effect of preharvest application of the yeast C. oleophila on population dynamics of epiphytic microbial population on wounded and unwounded grapefruit surface in the orchard and after harvest was also studied. In addition, the effect of preharvest application of the yeast C. oleophila on the development of postharvest decay was evaluated. Population studies conducted in the orchard showed that in control, non-treated fruit, colonization of wounded and unwounded grapefruit surface by naturally occurring filamentous fungi did not vary throughout the incubation period on the tree. On the other hand, colonization of intact and wounded fruit surface by naturally occurring yeasts was different. Yeasts colonized wounded surface rapidly and increased in numbers to about two orders of magnitude as compared to unwounded surface. On fruit treated with the yeast and kept on the tree, a different picture of fungal and yeast population had emerged. The detected fungal population on the yeast-treated intact surface was dramatically reduced and in treated wounds no fungi was detected. Yeast population on intact surface was relatively high immediately after the application of AspireTM and decreased to than 70% of that detected initially. In wounds, yeast population increased from 2.5 x 104 to about 4x106 after 72 hours of incubation at 20oC. Results of tests conducted to evaluate the effect of preharvest application of AspireTM on the development of postharvest decay indicated the validity of the approach.
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Fait, Aaron, Grant Cramer, and Avichai Perl. Towards improved grape nutrition and defense: The regulation of stilbene metabolism under drought. United States Department of Agriculture, May 2014. http://dx.doi.org/10.32747/2014.7594398.bard.
Full textAbstract:
The goals of the present research proposal were to elucidate the physiological and molecular basis of the regulation of stilbene metabolism in grape, against the background of (i) grape metabolic network behavior in response to drought and of (ii) varietal diversity. The specific objectives included the study of the physiology of the response of different grape cultivars to continuous WD; the characterization of the differences and commonalities of gene network topology associated with WD in berry skin across varieties; the study of the metabolic response of developing berries to continuous WD with specific attention to the stilbene compounds; the integration analysis of the omics data generated; the study of isolated drought-associated stress factors on the regulation of stilbene biosynthesis in plantaand in vitro. Background to the topic Grape quality has a complex relationship with water input. Regulated water deficit (WD) is known to improve wine grapes by reducing the vine growth (without affecting fruit yield) and boosting sugar content (Keller et al. 2008). On the other hand, irregular rainfall during the summer can lead to drought-associated damage of fruit developmental process and alter fruit metabolism (Downey et al., 2006; Tarara et al., 2008; Chalmers et al., 792). In areas undergoing desertification, WD is associated with high temperatures. This WD/high temperature synergism can limit the areas of grape cultivation and can damage yields and fruit quality. Grapes and wine are the major source of stilbenes in human nutrition, and multiple stilbene-derived compounds, including isomers, polymers and glycosylated forms, have also been characterized in grapes (Jeandet et al., 2002; Halls and Yu, 2008). Heterologous expression of stilbenesynthase (STS) in a variety of plants has led to an enhanced resistance to pathogens, but in others the association has not been proven (Kobayashi et al., 2000; Soleas et al., 1995). Tomato transgenic plants harboring a grape STS had increased levels of resveratrol, ascorbate, and glutathione at the expense of the anthocyanin pathways (Giovinazzo et al. 2005), further emphasizing the intermingled relation among secondary metabolic pathways. Stilbenes are are induced in green and fleshy parts of the berries by biotic and abiotic elicitors (Chong et al., 2009). As is the case for other classes of secondary metabolites, the biosynthesis of stilbenes is not very well understood, but it is known to be under tight spatial and temporal control, which limits the availability of these compounds from plant sources. Only very few studies have attempted to analyze the effects of different environmental components on stilbene accumulation (Jeandet et al., 1995; Martinez-Ortega et al., 2000). Targeted analyses have generally shown higher levels of resveratrol in the grape skin (induced), in seeded varieties, in varieties of wine grapes, and in dark-skinned varieties (Gatto et al., 2008; summarized by Bavaresco et al., 2009). Yet, the effect of the grape variety and the rootstock on stilbene metabolism has not yet been thoroughly investigated (Bavaresco et al., 2009). The study identified a link between vine hydraulic behavior and physiology of stress with the leaf metabolism, which the PIs believe can eventually lead to the modifications identified in the developing berries that interested the polyphenol metabolism and its regulation during development and under stress. Implications are discussed below.