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Journal articles on the topic 'Mechanical oxidation'

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Author: Grafiati
Published: 4 June 2021
Last updated: 28 January 2023

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1

Pandey, Priyanka, Smita Mohanty, and Sanjay Kumar Nayak. "A Novel Method of Mechanical Oxidation of CNT for Polymer Nanocomposite Application: Evaluation of Mechanical, Dynamic Mechanical, and Rheological Properties." International Journal of Chemical Engineering 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/623109.

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A new approach of oxidation of carbon nanotubes has been used to oxidize the CNTs. A comparative aspect of the mechanical oxidation and acid oxidation process has been established. FTIR analysis and titration method have shown the higher feasibility of the mechanical oxidation method to oxidize the CNTs. Comparatively less damage to the CNTs has been observed in case of mechanically oxidized as compared to acid oxidized CNTs. The mechanical properties of the nanocomposites reinforced with the acid oxidized CNT (ACNT) and mechanically oxidized CNTs (McCNT) were analyzed and relatively higher properties in the nanocomposites reinforced with McCNT were noticed. The less degree of entanglement in the McCNTs was noticed as compared to ACNTs. The dynamic mechanical analysis of the nanocomposites revealed much improved load transfer capability in the McCNT reinforced composites. Further, the rheological properties of the nanocomposites revealed the higher performance of McCNT reinforced composites.
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2

PANDEY, PRIYANKA, SMITA MOHANTY, and SANJAY K. NAYAK. "MECHANICAL OXIDATION OF MULTI-WALLED CARBON NANOTUBES AS A REPLACEMENT OF ACID OXIDATION METHOD." Nano 09, no. 08 (December 2014): 1450091. http://dx.doi.org/10.1142/s179329201450091x.

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In the present study, a candid approach using mechanical oxidation, for modification of multi-walled carbon nanotubes (CNTs) has been utilized, and its advantages over conventional acid oxidation methods have been established. Higher concentration of acidic groups was found in case of mechanically oxidized CNTs (i.e., McCNT) as compared to acid oxidized CNT (i.e., ACNT). Raman spectrum exhibited greater degree of transformation of sp2 carbon into sp3 carbon. X-ray diffraction (XRD) analysis revealed maintained crystalline organization in McCNT. The major finding of the study was that, the mechanical oxidation method can be used easily to replace the conventional acid treatment method. This is because in the mechanical oxidation crystalline organization of CNTs can be maintained, relatively higher number of acid groups can be incorporated, no loss to the mass of CNTs is allowed etc.
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3

Zhang, Yang, Xian-Cheng Zhang, and Shan-Tung Tu. "Coupled mechanical-oxidation modeling during silicon thermal oxidation process." AIP Advances 5, no. 9 (September 2015): 097105. http://dx.doi.org/10.1063/1.4930255.

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4

Musajan, Dilhumar, Maklinur Mamatjan, Riza Beken, and Mamatjan Yimit. "Impact of natural antioxidant systems on the oxidation resistance and mechanical properties of polypropylene." Polish Journal of Chemical Technology 22, no. 1 (March 1, 2020): 68–74. http://dx.doi.org/10.2478/pjct-2020-0010.

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AbstractThis paper describes the separation of oxidation resistant components from the seeds of pomegranate (PSA), grape (GSE) and sea buckthorn (SSE). The anti-oxidation properties of the resultant extracts, used as the natural anti-oxidants for polypropylene (PP), were compared with Irganox1010. The effects of these natural antioxidants on the antioxidant levels of PP samples were estimated by thermal oxidative aging and micromixed rheology, OIT, XRD, SEM, TEM and mechanical properties tests of samples before and after aging. The results show that adding PSA, GSE and SSE can obviously increase the mechanical properties of PP. In addition, the molding stability of polypropylene raw material is prolonged and improved. Moreover, the mechanical properties of the PP samples after 240 h of thermal oxidative aging indicates that, the best results, closest to the anti-oxidation ability of Irganox1010, can be obtained when the additive amount is 0.5% (wt%) for PSE or 0.7% (wt%) for GSE.
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5

Zergeroglu, Murat A., Michael J. McKenzie, R. Andrew Shanely, Darin Van Gammeren, Keith C. DeRuisseau, and Scott K. Powers. "Mechanical ventilation-induced oxidative stress in the diaphragm." Journal of Applied Physiology 95, no. 3 (September 2003): 1116–24. http://dx.doi.org/10.1152/japplphysiol.00824.2002.

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Prolonged mechanical ventilation (MV) results in oxidative damage in the diaphragm; however, it is unclear whether this MV-induced oxidative injury occurs rapidly or develops slowly over time. Furthermore, it is unknown whether both soluble (cytosolic) and insoluble (myofibrillar) proteins are equally susceptible to oxidation during MV. These experiments tested two hypotheses: 1) MV-induced oxidative injury in the diaphragm occurs within the first 6 h after the initiation of MV; and 2) MV is associated with oxidative modification of both soluble and insoluble proteins. Adult Sprague-Dawley rats were randomly divided into one of seven experimental groups: 1) control ( n = 8); 2) 3-h MV ( n = 8); 3) 6-h MV ( n = 6); 4) 18-h MV ( n = 8); 5) 3-h anesthesia-spontaneous breathing ( n = 8); 6) 6-h anesthesia-spontaneous breathing ( n = 6); and 7) 18-h anesthesia-spontaneous breathing ( n = 8). Markers of oxidative injury in the diaphragm included the measurement of reactive (protein) carbonyl derivatives (RCD) and total lipid hydroperoxides. Three hours of MV did not result in oxidative injury in the diaphragm. In contrast, both 6 and 18 h of MV promoted oxidative injury in the diaphragm, as indicated by increases in both protein RCD and lipid hydroperoxides. Electrophoretic separation of soluble and insoluble proteins indicated that the MV-induced accumulation of RCD was limited to insoluble proteins with molecular masses of ∼200, 120, 80, and 40 kDa. We conclude that MV results in a rapid onset of oxidative injury in the diaphragm and that insoluble proteins are primary targets of MV-induced protein oxidation.
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6

Shen, Q., S. Z. Li, L. Yang, Y. C. Zhou, Y. G. Wei, and T. Yuan. "Coupled mechanical-oxidation modeling during oxidation of thermal barrier coatings." Computational Materials Science 154 (November 2018): 538–46. http://dx.doi.org/10.1016/j.commatsci.2018.08.017.

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7

Avramenko, T. G., A. M. Kuryliuk, O. I. Nakonechna, and N. N. Belyavina. "Effect of TEG on Oxidation of TiC–ZrC Equimolar Blend at Mechanical Alloying." METALLOFIZIKA I NOVEISHIE TEKHNOLOGII 44, no. 6 (September 6, 2022): 713–24. http://dx.doi.org/10.15407/mfint.44.06.0713.

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8

Zhou, Lufang, Hazel Huang, Tracy A. McElfresh, Domenick A. Prosdocimo, and William C. Stanley. "Impact of anaerobic glycolysis and oxidative substrate selection on contractile function and mechanical efficiency during moderate severity ischemia." American Journal of Physiology-Heart and Circulatory Physiology 295, no. 3 (September 2008): H939—H945. http://dx.doi.org/10.1152/ajpheart.00561.2008.

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The role of anaerobic glycolysis and oxidative substrate selection on contractile function and mechanical efficiency during moderate severity myocardial ischemia is unclear. We hypothesize that 1) preventing anaerobic glycolysis worsens contractile function and mechanical efficiency and 2) increasing glycolysis and glucose oxidation while inhibiting free fatty acid oxidation improves contractile function during ischemia. Experiments were performed in anesthetized pigs, with regional ischemia induced by a 60% decrease in left anterior descending coronary artery blood flow for 40 min. Three groups were studied: 1) no treatment, 2) inhibition of glycolysis with iodoacetate (IAA), or 3) hyperinsulinemia and hyperglycemia (HI + HG). Glucose and free fatty acid oxidation were measured using radioisotopes and anaerobic glycolysis from net lactate efflux and myocardial lactate content. Regional contractile power was assessed from left ventricular pressure and segment length in the anterior wall. We found that preventing anaerobic glycolysis with IAA during ischemia in the absence of alterations in free fatty acid and glucose oxidation did not adversely affect contractile function or mechanical efficiency during myocardial ischemia, suggesting that anaerobic glycolysis is not essential for maintaining residual contractile function. Increasing glycolysis and glucose oxidation with HI + HG inhibited free fatty acid oxidation and improved contractile function and mechanical efficiency. In conclusion, these results show a dissociation between myocardial function and anaerobic glycolysis during moderate severity ischemia in vivo, suggesting that metabolic therapies should not be aimed at inhibiting anaerobic glycolysis per se, but rather activating insulin signaling and/or enhancing carbohydrate oxidation and/or decreasing fatty acid oxidation.
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9

Kar, Prasenjit, Ke Wang, and Hong Liang. "Oxidation of Tantalum with Mechanical Force." Electrochemical and Solid-State Letters 11, no. 2 (2008): C13. http://dx.doi.org/10.1149/1.2820616.

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10

Schütze, Michael. "Mechanical aspects of high-temperature oxidation." Corrosion Science 35, no. 5-8 (January 1993): 955–63. http://dx.doi.org/10.1016/0010-938x(93)90314-7.

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11

Yang, Xiaozhe, Xu Yang, Haiyang Gu, Kentaro Kawai, Kenta Arima, and Kazuya Yamamura. "Charge Utilization Efficiency and Side Reactions in the Electrochemical Mechanical Polishing of 4H-SiC (0001)." Journal of The Electrochemical Society 169, no. 2 (February 1, 2022): 023501. http://dx.doi.org/10.1149/1945-7111/ac4b1f.

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Slurryless electrochemical mechanical polishing (ECMP) is very effective in the polishing of silicon carbide (SiC) wafers. To achieve a high material removal rate (MRR) of SiC wafer using ECMP with low electrical energy loss, charge utilization efficiency in the anodic oxidation of the SiC surface was investigated and the underlying mechanism was clarified by modeling the anodic oxidation system of SiC in 1 wt% NaCl aqueous solution. The charge utilization efficiency in the anodic oxidation of SiC was found to be constant when the current density was less than 20 mA cm−2 and significantly decreased when the current density was greater than 30 mA cm−2, resulting in a significant reduction in the MRR. Modeling of the anodic oxidation system indicates that the charge utilization efficiency depended on the potential applied on the SiC surface: the oxidation of SiC occupied the dominant position in the anodizing system when the potential is lower than 25 V vs Ag∣AgCl, charge utilization efficiency greatly decreased when the applied potential was greater than 25 V owing to the occurrence of oxidations of the H2O and Cl−. This research provides both a theoretical and practical foundation for using ECMP to polish SiC wafers.
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12

Yang, Lingwei, Xueren Xiao, Liping Liu, Jie Luo, Kai Jiang, Xinxing Han, Changhao Zhao, Jun Zhang, and Guolin Wang. "Dynamic oxidation mechanism of carbon fiber reinforced SiC matrix composite in high-enthalpy and high-speed plasmas." Journal of Advanced Ceramics 11, no. 2 (January 11, 2022): 365–77. http://dx.doi.org/10.1007/s40145-021-0540-8.

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AbstractThis work employed an inductively coupled plasma wind tunnel to study the dynamic oxidation mechanisms of carbon fiber reinforced SiC matrix composite (Cf/SiC) in high-enthalpy and high-speed plasmas. The results highlighted a transition of passive/active oxidations of SiC at 800–1600 °C and 1–5 kPa. Specially, the active oxidation led to the corrosion of the SiC coating and interruption of the SiO2 growth. The transition borders of active/passive oxidations were thus defined with respect to oxidation temperature and partial pressure of atomic O in the high-enthalpy and high-speed plasmas. In the transition and passive domains, the SiC dissipation was negligible. By multiple dynamic oxidations of Cf/SiC in the domains, the SiO2 thickness was not monotonously increased due to the competing mechanisms of passive oxidation of SiC and dissipation of SiO2. In addition, the mechanical properties of the SiC coating/matrix and the Cf/SiC were maintained after long-term dynamic oxidations, which suggested an excellent thermal stability of Cf/SiC serving in thermal protection systems (TPSs) of reusable hypersonic vehicles.
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13

BARBUT, S., H. H. DRAPER, and P. D. COLE. "Effect of Mechanical Deboner Head Pressure on Lipid Oxidation in Poultry Meat." Journal of Food Protection 52, no. 1 (January 1, 1989): 21–25. http://dx.doi.org/10.4315/0362-028x-52.1.21.

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The oxidation rates of mechanically deboned poultry meat (MDPM) from whole breasts of roasters obtained under different deboner head pressures (40, 75, 120 and 150 lb/in2) were determined. Mechanical deboning significantly (P<0.05) increased fat, ash, calcium and iron content, and reduced moisture and protein levels, compared to hand deboning. The highest head pressure resulted in significantly lower fat and higher iron content than the other treatments and produced the slowest rate of oxidation. The lowest head pressure (40 lb/in2) resulted in the highest oxidation rate. Fatty acid analysis indicated that 150 lb/in2 caused a loss of linoleic acids with a resulting increase in the proportion of C16 fatty acids. Commercial MDPM samples prepared from broiler backs & necks showed significantly (p<0.05) higher oxidation rates than fowl frames and all of the mechanically deboned roaster meat samples except those deboned at 40 lb/in2.
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14

Li, Gui-Yang, and J. L. Koenig. "A Review of Rubber Oxidation." Rubber Chemistry and Technology 78, no. 2 (May 1, 2005): 355–90. http://dx.doi.org/10.5254/1.3547888.

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Abstract The aging of rubber caused by oxidative degradation leads to the deterioration in the physical and mechanical properties of vulcanized rubbers. In an effort to improve the oxidative stability of rubbers and elastomers, considerable amount of work has been carried out over the past 50 years (especially in the most recent 5 years) in order to understand degradation modes and effects in rubber due to the action of oxygen and ozone in the air. Different mechanisms have been proposed to interpret the experimental data relative to the oxidation of rubber. The diffusion limited theory has been widely used in the literature and verified by many experiments. Various instrumental techniques have been utilized to characterize the oxidation and degradation and their mechanisms in rubber compounds. Recently, FTIR imaging has demonstrated a unique combination of spectral and spatial resolution which allows not only the identification of the oxidation products but also their spatial distribution from the oxygen penetrating surfaces. This critical review will cover the major developments in our understanding of the oxidation of rubbers.
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15

Li, Gui-Yang, and J. L. Koenig. "A Review of Rubber Oxidation." Rubber Chemistry and Technology 78, no. 3 (July 1, 2005): 355–90. http://dx.doi.org/10.5254/1.3547889.

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Abstract The aging of rubber caused by oxidative degradation leads to the deterioration in the physical and mechanical properties of vulcanized rubbers. In an effort to improve the oxidative stability of rubbers and elastomers, considerable amount of work has been carried out over the past 50 years (especially in the most recent 5 years) in order to understand degradation modes and effects in rubber due to the action of oxygen and ozone in the air. Different mechanisms have been proposed to interpret the experimental data relative to the oxidation of rubber. The diffusion limited theory has been widely used in the literature and verified by many experiments. Various instrumental techniques have been utilized to characterize the oxidation and degradation and their mechanisms in rubber compounds. Recently, FTIR imaging has demonstrated a unique combination of spectral and spatial resolution which allows not only the identification of the oxidation products but also their spatial distribution from the oxygen penetrating surfaces. This critical review will cover the major developments in our understanding of the oxidation of rubbers.
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16

Petersen, J. Claine, and P. Michael Harnsberger. "Asphalt Aging: Dual Oxidation Mechanism and Its Interrelationships with Asphalt Composition and Oxidative Age Hardening." Transportation Research Record: Journal of the Transportation Research Board 1638, no. 1 (January 1998): 47–55. http://dx.doi.org/10.3141/1638-06.

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The kinetic data and chemistry of asphalt oxidative age hardening suggested a sequential, dual mechanism for asphalt oxidation. The dual mechanism rationalizes conflicts between earlier mechanistic investigations and explains the hyperbolic-like, time-versus-property plots characteristic of asphalt oxidative aging. The oxidation kinetics provide further confirmation of the asphalt microstructural model. It is proposed that the rapid initial oxidation rate of asphalt results from reaction of oxygen with limited amounts of highly reactive hydrocarbons. Final oxidation products of this initial reaction are sulfoxides and, most likely, ring aromatization. During this initial reaction, a slower oxidation reaction of asphalt benzylic carbons is initiated; final products are ketones and sulfoxides. The ratio of ketones to sulfoxides formed and the rate of age hardening were found to be dependent on temperature and oxygen pressure. Low-temperature oxidative aging, as occurs in pavements, was found significantly more sensitive to variations in temperature and asphalt composition than 100°C pressure vessel aging.
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17

Javed, Mahjabeen, Seelay Tasmim, Mustafa K. Abdelrahman, Cedric P. Ambulo, and Taylor H. Ware. "Degradation-Induced Actuation in Oxidation-Responsive Liquid Crystal Elastomers." Crystals 10, no. 5 (May 25, 2020): 420. http://dx.doi.org/10.3390/cryst10050420.

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Stimuli-responsive materials that exhibit a mechanical response to specific biological conditions are of considerable interest for responsive, implantable medical devices. Herein, we report the synthesis, processing and characterization of oxidation-responsive liquid crystal elastomers that demonstrate programmable shape changes in response to reactive oxygen species. Direct ink writing (DIW) is used to fabricate Liquid Crystal Elastomers (LCEs) with programmed molecular orientation and anisotropic mechanical properties. LCE structures were immersed in different media (oxidative, basic and saline) at body temperature to measure in vitro degradation. Oxidation-sensitive hydrophobic thioether linkages transition to hydrophilic sulfoxide and sulfone groups. The introduction of these polar moieties brings about anisotropic swelling of the polymer network in an aqueous environment, inducing complex shape changes. 3D-printed uniaxial strips exhibit 8% contraction along the nematic director and 16% orthogonal expansion in oxidative media, while printed LCEs azimuthally deform into cones 19 times their original thickness. Ultimately, these LCEs degrade completely. In contrast, LCEs subjected to basic and saline solutions showed no apparent response. These oxidation-responsive LCEs with programmable shape changes may enable a wide range of applications in target specific drug delivery systems and other diagnostic and therapeutic tools.
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18

Waldi, Muhamad, Helmi Bagas Samudra, Ahmad Maulana Arkan Leksana, Djoko Hadi Prajitno, and Haris Tjahaya. "Cyclic Oxidation Behavior of HVOF Thermally Sprayed WC Cermet Based on AISI 1045 Steel." Majalah Ilmiah Pengkajian Industri 16, no. 2 (August 30, 2022): 73–80. http://dx.doi.org/10.29122/mipi.v16i2.5311.

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Thermal spray coating technology High-Velocity Oxygen Fuel (HVOF) has become one of solution for metal protect and parts recondition that work in critical environments such as oxidative, erosive, and corrosive. One of the thermal spray coatings (TSC) application has been carried out to improve the oxidation resistance of the Induce Draft Fan (IDF) as a part on coal fired steam power plant unit. Cermet WC10Co4Cr and WC17Co are intended to sustain the AISI 1045 steel substrate against the oxidative environment. In this works, the cyclic oxidation at a temperature 500oC were conducted to reveal the oxidation resistance behavior of the coatings. Several mechanical tests are also presented including surface roughness of the coatings, coatings microhardness, and coatings adhesion. The coatings morphology was also characterized using SEM microscope, as well as X-ray diffraction (XRD) for phase analysis after the oxidation test. KeywordHVOF, Oxidation resistance, Induce draft fan.
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19

Dake, Akihiro, Hai Vu Pham, and Makoto Nanko. "Mechanical Recovery of Ni/Al2O3 Nanocomposites after Pre-Oxidations at High Temperatures." Materials Science Forum 868 (August 2016): 12–17. http://dx.doi.org/10.4028/www.scientific.net/msf.868.12.

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Ni/Al2O3 nanocomposites have a crack healing function which results in recovery of mechanical strength. The function is caused by oxidations of Ni particles within matrix. Oxidation of Ni dispersion also results in the evolution of oxidized zone, which consists of NiAl2O4 grains in Al2O3 matrix. Degradations by high-temperature oxidation before introduction of surface crack is necessary to investigate for estimating the life time of the present material system. Samples of Ni/Al2O3 nanocomposites were prepared by using pulsed electric current sintering and pre-oxidized at 1200°C for 1-6 d in air. Surface cracks were given by the Vickers indentation at 49 N for 10 s. The samples were oxidized again at 1200°C for 6 h in air to heal the surface cracks. Longer pre-oxidation time of samples results in degradation of the performance of surface crack disappearance. Bending strength of healed samples with 2 d pre-oxidation was comparable with the samples before cracks introduction. After oxidation at 1200°C for 6 h in air, the partially disappearance of cracks was observed on 6 d pre-oxidized samples. Hence, the recovery of bending strength depends on thickness of oxidized zone and depth of surface cracks.
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20

Schonekess, B. O., M. F. Allard, and G. D. Lopaschuk. "Recovery of glycolysis and oxidative metabolism during postischemic reperfusion of hypertrophied rat hearts." American Journal of Physiology-Heart and Circulatory Physiology 271, no. 2 (August 1, 1996): H798—H805. http://dx.doi.org/10.1152/ajpheart.1996.271.2.h798.

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We investigated the source and extent of recovery of ATP production during postischemic reperfusion of isolated working hearts from abdominal aortic-banded rats. Rates of glycolysis, glucose oxidation, lactate oxidation, and palmitate oxidation were measured in hypertrophied and control hearts [perfused with (in mM) 11 glucose, 0.5 lactate, and 1.2 palmitate] during and after 30 min of no-flow ischemia. In the initial aerobic period glycolytic rates were 1.87-fold higher in hypertrophied hearts compared with control hearts (P < 0.05), with rates of carbohydrate and palmitate oxidation being similar. During reperfusion, hypertrophied hearts recovered 40% of preischemic function compared with 71% in control hearts. Rates of glycolysis during reperfusion of hypertrophied hearts remained accelerated compared with control hearts (2.01-fold higher, P < 0.05), whereas oxidative metabolism returned to preischemic values in both groups. The efficiency of converting ATP production into mechanical work decreased to 29% of preischemic values in hypertrophied hearts during the postischemic reperfusion compared with a decrease to only 59% of preischemic values in control hearts. This suggests that the recovery of glycolysis and oxidative metabolism in the hypertrophied heart during postischemic reperfusion is not impaired, but rather the efficiency of converting ATP produced into mechanical function decreases.
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21

Omar, Haidar, Nikolaos Michailidis, Stefanos Skolianos, Azarias Mavropoulos, Sofia Tsipas, and Nikiforos Maragoudakis. "Determination of Mechanical and Corrosion Properties of Boride Coating on P91 Steel." Key Engineering Materials 438 (May 2010): 89–96. http://dx.doi.org/10.4028/www.scientific.net/kem.438.89.

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In many applications, even high-performance alloys have to be covered with protective coatings, providing higher corrosion and oxidation resistance, as compared to the alloy itself. This study investigates the feasibility to apply boron coatings on P91 steel by pack cementation process, to increase the steel durability in oxidative and corrosive environments, as well as its mechanical strength. Micro-indentation and the coating impact test were used to characterize the hardness and fatigue properties of the film respectively. The coating corrosion resistance versus the one of the uncoated P91 steel was tested in a salt spray chamber. The coating performance was characterized by optical and scanning electron microscopy to check the consistency of the coated and uncoated surfaces and the oxidation extend. The results show an increased film strength, good fatigue performance and adequate corrosion resistance.
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22

Shoji, Mitsuo, Yukihiro Abe, Mauro Boero, Yasuteru Shigeta, and Yoshiaki Nishiya. "Reaction mechanism of N-cyclopropylglycine oxidation by monomeric sarcosine oxidase." Physical Chemistry Chemical Physics 22, no. 29 (2020): 16552–61. http://dx.doi.org/10.1039/d0cp01679a.

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23

Korbutowicz, R., and A. Zakrzewski. "Preliminary comparison of three processes of AlN oxidation: dry, wet and mixed ones." Materials Science-Poland 34, no. 1 (March 1, 2016): 157–63. http://dx.doi.org/10.1515/msp-2016-0010.

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AbstractThree methods of AlN layers oxidation: dry, wet and mixed (wet with oxygen) were compared. Some physical parameters of oxidized thin films of aluminum nitride (AlN) layers grown on silicon Si(1 1 1) were investigated by means Energy-Dispersive X-ray Spectroscopy (EDS) and Spectroscopic Ellipsometry (SE). Three series of the thermal oxidations processes were carried out at 1012 °C in pure nitrogen as carrying gas and various gas ambients: (a) dry oxidation with oxygen, (b) wet oxidation with water steam and (c) mixed atmosphere with various process times. All the research methods have shown that along with the rising of the oxidation time, AlN layer across the aluminum oxide nitride transforms to aluminum oxide. The mixed oxidation was a faster method than the dry or wet ones.
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24

WANG, RUZHUAN, WEIGUO LI, and DAINING FANG. "A THERMO-DAMAGE STRENGTH MODEL FOR THE SiC-DEPLETED LAYER OF ULTRA-HIGH-TEMPERATURE CERAMICS ON HIGH TEMPERATURE OXIDATION." International Journal of Applied Mechanics 05, no. 03 (September 2013): 1350026. http://dx.doi.org/10.1142/s1758825113500269.

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At high temperatures above 1650°C, the SiC -depleted layer of ultra-high-temperature ceramics which has high porosity appears during the oxidation process. In this present paper, based on the studies of the oxidative mechanisms and the fracture mechanisms of ultra-high-temperature ceramics under normal and high temperatures, a thermo-damage strength model for the SiC -depleted layer on high temperature oxidation was proposed. Using the model, the phase transformation, microstructure development and fracture performance in the SiC -depleted layer on high temperature oxidation were studied in detail. The study showed that the porosity is mainly related to the oxidation of SiC . And while the SiC is substantially completely oxidized, only a very small part of matrix is oxidized. The fracture strength of the SiC -depleted layer degrades seriously during the high temperature oxidation process. And the bigger the initial volume fraction of SiC , the lower the fracture strength of the SiC -depleted layer is. This layer may become the origin of failure of material, thus the further researches should be undertaken to improve the oxidation behavior for the ultra-high-temperature ceramics in a wider temperature range.
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25

Hirvonen, J.-P., P. Torri, R. Lappalainen, J. Likonen, H. Kung, J. R. Jervis, and M. Nastasi. "Oxidation of MoSi2/SiC nanolayered composite." Journal of Materials Research 13, no. 4 (April 1998): 965–73. http://dx.doi.org/10.1557/jmr.1998.0135.

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The oxidation behavior of a nanolayered MoSi2/SiC composite material was determined at the temperature range of 400–900 °C in wet oxidation conditions. The samples were produced in the form of thin films using a sputtering technique from two different sources, and a rotating substrate holder, onto silicon single crystals and low carbon steel. For comparison, the oxidations of both constituents, MoSi2 and SiC, produced with the same sputtering technique, were measured separately. The microstructure of the MoSi2/SiC samples was determined with high resolution transmission electron microscopy (HRTEM), and the composition of the sputtered samples was measured using backscattering (BS) of protons. For quantitative determination of oxidation, the nuclear reaction 16O(d, p)17O was utilized. Oxide layers were also analyzed using a secondary ion mass spectrometry (SIMS) and the appearance of the oxidized surface with a scanning electron microscopy (SEM). As expected, the SiC films had both the lowest initial oxidation and steady state oxidation rate. The results show that the oxidation behavior of the MoSi2/SiC nanolayered composite material differs from that of both its constituents and involves a degradation mechanism of its own, resulting in the highest oxidation during the initial phase of the oxidation. A steady-state oxidation rate was observed after the initial transient phase to be the highest for the metastable C40 structure of the single MoSi2 layer. The oxidation rate of the nanolayered structure was retarded by the SiC layers. No signs of pest disintegration were observed on either of the MoSi2 containing coatings during the steady-state phase of the oxidation at 500 °C up to 40 h. Our results show that the oxidation of nanolayered structures can be only in part explained by the oxidation behavior of the constituents and that during the steady-state oxidation of the nanolayered structure the oxidation rate is largely determined by the constituent with the lowest oxidation rate and by the layered structure.
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26

Hu, Chun Yan, Zhi Qiang Kong, Xin Ling Liu, and Chun Hu Tao. "Effects of Gas Film Hole on Mechanical Property and Oxidative Damage of Turbine Blades." Materials Science Forum 944 (January 2019): 421–25. http://dx.doi.org/10.4028/www.scientific.net/msf.944.421.

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With the development of aero-engine with high specific flux, high thrus-weight ratio, and high turbine inlet temperature, it is an effective way to improve the cooling efficiency by designing dense gas film holes on the blade surface of the turbine blades, especially at the intake side. However, the introduction of gas film holes destroys the geometrical integrity of the blade structure, resulting in a multiaxial high stress state of the blade material around the small holes, which seriously affects the strength and life of the cooling blades. In addition, the geometry design of the gas film holes also directly affects the temperature and the oxidation rate of the turbine rotor blades. In this paper, the researches on the mechanical properties and oxidative damage of the gas film holes at home and abroad in recent years have been systematically introduced. The effects of gas film holes on the durability and fatigue properties, the high temperature oxidation behavior of single crystal superalloys, and the thin-walled effect of oxidative damage of gas film holes have been systematically described.
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27

Cheng, Lin, Michael J. O’Loughlin, Alexander V. Suvorov, Edward R. Van Brunt, Albert A. Burk, Anant K. Agarwal, and John W. Palmour. "Improvement of Minority Carrier Lifetime in Thick 4H-SiC Epi-layers by Multiple Thermal Oxidations and Anneals." MRS Proceedings 1538 (2013): 329–33. http://dx.doi.org/10.1557/opl.2013.574.

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ABSTRACTThis paper details the development of a technique to improve the minority carrier lifetime of 4H-SiC thick (≥ 100 μm) n-type epitaxial layers through multiple thermal oxidations. A steady improvement in lifetime is seen with each oxidation step, improving from a starting ambipolar carrier lifetime of 1.09 µs to 11.2 µs after 4 oxidation steps and a high-temperature anneal. This multiple-oxidation lifetime enhancement technique is compared to a single high-temperature oxidation step, and a carbon implantation followed by a high-temperature anneal, which are traditional ways to achieve high ambipolar lifetime in 4H-SiC n-type epilayers. The multiple oxidation treatment resulted in a high minimum carrier lifetime of 6 µs, compared to < 2 µs for other treatments. The implications of lifetime enhancement to high-voltage/high-current 4H-SiC power devices are also discussed.
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Eser, Onur, and S. Kurama. "Improvement in the Oxidation Resistance of β-SiAlON Ceramics Produced from Mechanically Milled Powders." Journal of Nano Research 18-19 (July 2012): 281–90. http://dx.doi.org/10.4028/www.scientific.net/jnanor.18-19.281.

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In the present study the oxidation behavior of β-SiAlON ceramics, which were produced from conventional and high energy mechanical milled powders, was investigated. High energy mechanically milled powders have lower particle sizes ( 130 nm) than those of conventional powders (216 nm) and fully densified at lower temperatures with less amount of additives. The amount of additive is an important parameter to improve the high temperature oxidation resistance of SiAlON ceramics. The cyclic and isothermal oxidation tests were carried out at 1300 and 1400°C in dry air environment. The weight gain of oxidized samples was measured during the oxidation process. The alteration of oxide layer was analyzed by XRD and SEM. The results indicate that oxidation resistance of the samples produced from mechanically milled powders with less amount of additive is higher than that of conventional one. Therefore, β-SiAlON ceramics which were sintered at 100°C lower temperatures with less amount of additive (3.5 wt. % Y2O3), showed a better oxidation resistance.
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29

Kutuzova, Larysa, Olga Molentor, Feng Wu, Wenyao Song, Andreas Kandelbauer, and Günter Lorenz. "Protective role of vitamin E to reduce oxidative degradation of soft implantable polyurethanes: In vitro study." Current Directions in Biomedical Engineering 5, no. 1 (September 1, 2019): 449–51. http://dx.doi.org/10.1515/cdbme-2019-0113.

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AbstractVitamin E (VitE) additives are important in treating osteoarthritis inclusive cartilage regeneration due to their antioxidant and anti-inflammatory properties. The present research study focuses on the ability of biological antioxidant VitE (alpha-tocopherol isoform) to reduce or minimize oxidative degradation of soft implantable polyurethane (PU) elastomers after extended periods of time (5 months) in vitro. The effect of the oxidation storage media on the morphology of the segmented PUs was evaluated by mechanical softening, crystallization and melting behavior of both soft and hard segments (SS, HS) using dynamic mechanical analysis (DMA). Bulk mechanical properties of the potential implant materials during ageing were predicted from comprehensive mechanical testing of the biomaterials under tension and compression cyclic loads. 5-months in vitro data suggest that the prepared siloxane-poly(carbonate-urethane) formulations have sufficient resistance against degradation to be suitable materials for chondral long-term bio-stable implants. Most importantly, the positive effect of incorporating VitE (0.5 or 1.0% w/w) as bio-antioxidant and lubricant on the bio-stability was observed for all PU-types. VitE-additives protected the surface layer from erosion and cracking during chemical oxidation in vitro as well as from thermal oxidation during extrusion re-processing.
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Gergin, İlknur, Ezgi Ismar, and A. Sezai Sarac. "Oxidative stabilization of polyacrylonitrile nanofibers and carbon nanofibers containing graphene oxide (GO): a spectroscopic and electrochemical study." Beilstein Journal of Nanotechnology 8 (August 7, 2017): 1616–28. http://dx.doi.org/10.3762/bjnano.8.161.

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In this study, a precursor for carbon nanofibers (CNF) was fabricated via electrospinning and carbonized through a thermal process. Before carbonization, oxidative stabilization should be applied, and the oxidation mechanism also plays an important role during carbonization. Thus, the understanding of the oxidation mechanism is an essential part of the production of CNF. The oxidation process of polyacrylonitrile was studied and nanofiber webs containing graphene oxide (GO) are obtained to improve the electrochemical properties of CNF. Structural and morphological characterizations of the webs are carried out by using attenuated total reflectance Fourier transform infrared spectroscopy and Raman spectroscopy, scanning electron microscopy, atomic force microscopy and transmission electron microscopy. Mechanical tests are performed with a dynamic mechanical analyzer, and thermal studies are conducted by using thermogravimetric analysis. Electrochemical impedance spectroscopy, and cyclic voltammetry are used to investigate capacitive behavior of the products. The proposed equivalent circuit model was consistent with charge-transfer processes taking place at interior pores filled with electrolyte.
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31

Qiu, Tian, Jin Ling Wang, Heng Xue Xiang, Ze Xu Hu, Li Ping Zhu, and Mei Fang Zhu. "Improving the Oxidation Resistance of Polyphenylene Sulfide Fibers by Doping Copper Nanoparticles Loaded Halloysite Nanotubes." Materials Science Forum 1070 (October 13, 2022): 21–31. http://dx.doi.org/10.4028/p-gof4m1.

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Polyphenylene sulfide (PPS) fiber is widely used in the fields of high-temperature filtration, protective clothing, electronics, automobile, and aircrafts sectors relying on its excellent heat and chemical resistance. However, PPS fiber is easily oxidized under high temperature, which vastly restricts its applications. In this study, using the copper nanoparticles loaded halloysite nanotubes (HNTs@Cu) as a nanofiller, we prepared a PPS composite fiber with improved oxidation resistance. The successful loading of copper nanoparticles into HNTs was demonstrated through TEM and elemental analysis. The crystallinity, orientation, thermal and mechanical properties of PPS nanocomposite fibers were investigated via DSC, XRD, WXRD, TGA and mechanical test. While the mechanical performance of the composite fibers was slightly decreased, the thermal stability was improved when comparing to the neat PPS fiber. The composite fiber with 1.0 wt.% loading of HNTs@Cu showed an over 100% retention rate of breaking strength after thermal oxidative aging, suggesting an improvement in oxidation resistance of PPS fiber. This work provides an effective and accessible method for improving the thermal stability and oxidation resistance of PPS fibers, which thereby helps to extend the applications of PPS fibers in high temperature environment.
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Kon, Tomohiko, Tomomi Honda, and Akira Sasaki. "Estimation of the Oxidative Deterioration of Turbine Oil Using Membrane Patch Color." Advances in Tribology 2020 (February 7, 2020): 1–8. http://dx.doi.org/10.1155/2020/1708408.

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Lubricating oils degrade into two main products: oxidation products and solid particles. Oxidation products, called varnish, of turbine oils for power generation have become a particularly serious problem in recent years. The first step in determining the potential to produce varnish is to determine the remaining life of the antioxidant in the oil, but even though turbine oil may have antioxidants of sufficient longevity, varnish problems still occur frequently. Accordingly, to prevent varnish, it is necessary to diagnose oil oxidation products. Thus, the authors have developed a diagnostic method using membrane patch color, but the relationship between membrane patch color and the remaining life of turbine oils has yet to be clarified. This paper investigates a new method for estimating the oxidative degradation of turbine oils that uses membrane patch color and the dry turbine oxidation stability test (dry TOST) based on oxidation products and the remaining life of the turbine oils. Sample oils were prepared and degraded by oxidation in the laboratory using a dry TOST apparatus, and the membrane patch color was measured using a colorimetric patch analyzer (CPA). The relationship between membrane patch color and the rotating pressure vessel oxidation test (RPVOT) residual rate was then investigated. The results show that the new estimation method using the CPA and dry TOST is able to monitor the decrease of the RPVOT residual rate from the early stages of oxidative deterioration.
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Jiang, Tao, Zhi Hao Jin, Jian Feng Yang, and Guan Jun Qiao. "High Temperature Oxidation Behavior of the B4C/BN Composites." Advanced Materials Research 105-106 (April 2010): 133–36. http://dx.doi.org/10.4028/www.scientific.net/amr.105-106.133.

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The B4C/BN composites were fabricated by hot-pressing process. The microstructure, mechanical properties and oxidation resistances of the B4C/BN composites were investigated. It was shown that the h-BN particles were distributed in the B4C ceramics matrix. The mechanical properties of the B4C/BN microcomposites and the B4C/BN nanocomposites decreased gradually with the increasing content of h-BN. The mechanical properties of the B4C/BN nanocomposites were significantly improved in comparison with the B4C/BN microcomposites. The oxidation processes were performed at 1000oC, 1100oC, 1200oC, 1300oC for 20h. The oxidation curves of the B4C monolith, the B4C/BN microcomposites and the B4C/BN nanocomposites decreased gradually with the increase of oxidation temperature and oxidation time. The specimen’s weight and the oxidation resistance decreased gradually with the increase of oxidation temperature and oxidation time. The specimens remained good oxidation resistance at 1000oC; the oxidation resistance decreased remarkably at 1300oC. The decreasing specimen’s weight was attributed to the evaporation of B2O3 which produced by oxidation process of B4C and h-BN. The phase composition and microstructure of specimen’s surface after oxidation process were investigated by XRD and SEM.
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34

Hwang, Chii-Shyang, and Tien-Jui Liu. "Microstructure and mechanical properties of NiAl/Al2O3 composites." Journal of Materials Research 14, no. 1 (January 1999): 75–82. http://dx.doi.org/10.1557/jmr.1999.0013.

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To improve mechanical properties of NiAl, a method for making NiAl matrix composites containing oxide ceramics is introduced. The method involves oxidation of NiAl powder in air to form a thin and uniform oxide scale, mainly Al2O3, on the NiAl particles. The Al2O3 contents increase with increasing oxidation temperature. The NiAl/Al2O3 composites are then formed by hot-pressing the oxidized NiAl powder under vacuum atmosphere. Al2O3 inhibits the grain growth of NiAl during the hot-pressing. The residual stress and the Ni-rich NiAl composition exist in the hot-pressed NiAl/Al2O3 composites. Strength and toughness data on NiAl/Al2O3 composites indicate that the use of oxidation of NiAl powder is a viable technique for improving these properties over that of monolithic NiAl.
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35

Chang, Li-Chun, Ming-Ching Sung, Yung-I. Chen, and Chin-Han Tseng. "Mechanical properties and oxidation behavior of CrWSiN films." Surface and Coatings Technology 437 (May 2022): 128368. http://dx.doi.org/10.1016/j.surfcoat.2022.128368.

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36

CHOE, H., and D. DUNAND. "Mechanical properties of oxidation-resistant Ni–Cr foams." Materials Science and Engineering A 384, no. 1-2 (October 25, 2004): 184–93. http://dx.doi.org/10.1016/s0921-5093(04)00814-7.

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37

Ng, D., M. Kulkarni, J. Johnson, A. Zinovev, D. Yang, and H. Liang. "Oxidation and removal mechanisms during chemical–mechanical planarization." Wear 263, no. 7-12 (September 2007): 1477–83. http://dx.doi.org/10.1016/j.wear.2006.11.023.

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38

Mitra, R. "Mechanical behaviour and oxidation resistance of structural silicides." International Materials Reviews 51, no. 1 (February 2006): 13–64. http://dx.doi.org/10.1179/174328006x79454.

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39

Tsipas, D. N., H. Lefakis, R. D. Rawlings, A. Staton-Bevan, and S. A. Tsipas. "MECHANICAL AND OXIDATION PROPERTIES OF Ni3Al-BASED ALLOYS." Materials and Manufacturing Processes 16, no. 1 (January 31, 2001): 127–40. http://dx.doi.org/10.1081/amp-100103702.

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40

Tzeng, Chin-Han, Li-Chun Chang, and Yung-I. Chen. "Mechanical Properties and Oxidation Behavior of TaWSiN Films." Materials 15, no. 22 (November 17, 2022): 8179. http://dx.doi.org/10.3390/ma15228179.

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This study explored the structural characteristics, mechanical properties, and oxidation behavior of W-enriched TaWSiN films prepared through co-sputtering. The atomic ratios [W/(W + Ta)] of the as-deposited films maintained a range of 0.77–0.81. The TaWSiN films with a Si content of 0–13 at.% were crystalline, whereas the film with 20 at.% Si was amorphous. The hardness and Young’s modulus of crystalline TaWSiN films maintained high levels of 26.5–29.9 GPa and 286–381 GPa, respectively, whereas the hardness and Young’s modulus of the amorphous Ta7W33Si20N40 films exhibited low levels of 18.2 and 229 GPa, respectively. The oxidation behavior of TaWSiN films was investigated after annealing at 600 °C in a 1%O2–Ar atmosphere, and cone-like Ta0.3W0.7O2.85 oxides formed and extruded from the TaWSiN films.
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41

Song, Ruo Kang, Mai Cang Zhang, Jian Xing Dong, and Chen Yang Du. "Investigation of Cr34Ni45 Ethylene Cracking Furnace Tube in Service." Advanced Materials Research 834-836 (October 2013): 390–400. http://dx.doi.org/10.4028/www.scientific.net/amr.834-836.390.

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The structure and mechanical property changes of Cr34Ni45 ethylene cracking furnace tube serviced for different time (as-cast, 1.5 years and 6 years) are systematically investigated by using SEM, EMPA, XRD and mechanics performance test methods. The microstructure of the as-cast alloy consists of austenitic matrix, NbC and M7C3 primary carbides. Eutectic M7C3 transform into M23C6, and the NbC transform into Nb3Ni2Si which is so-called η-phase during service, accompany with precipitation of secondary M23C6. Furthermore, comparing to original uniform microstructure distribution, there are three zones including oxidation layer, carbides depletion zone and carbides-rich zone at the subsurface region of the inner-wall of Cr35Ni45 tubes after long time service. Oxidation behaviors at high temperature consist of external oxidation of chromium and internal oxidation of silicon. The carburizing behavior of Cr35Ni45 tube is mainly caused by the coking on the surface of inner-wall, but carburization of the serviced tubes are both at lesser-degree because of the auto-remediation of outer oxidation layer. High temperature service heavily reduced mechanical performance of the tubes, and fracture mode transform from a mixed mode to a brittle one during service.
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42

Yang, Jialin, Yunting Guo, Wei Zai, Siyuan Ma, Liang Dong, and Guangyu Li. "Preparation and properties of the anodized film on Fe-Cr-Al alloy surface." Anti-Corrosion Methods and Materials 67, no. 4 (May 18, 2020): 379–86. http://dx.doi.org/10.1108/acmm-11-2019-2209.

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Purpose This paper aims to find a way to improve the surface insulation, corrosion resistance and mechanical properties of Fe-Cr-Al electrothermal alloy, exploring the best oxidation condition and analyzing the oxidation mechanism. Design/methodology/approach Electrochemical workstation was used for anodic oxidation, and the effect of current density, ethylene glycol concentration and oxidation time on properties of the film were investigated by resistivity test, scanning electron microscope, electrochemical tests (potentiodynamic polarization and electrochemical impedance spectroscopy) and mechanical tests, and the oxidation process was analyzed by X-ray photoelectron spectroscopy (XPS). Findings According to the potential-time curves of anodic oxidation and the analysis of XPS, the whole oxidation process can be divided into four stages. When the current density is 0.8 A/dm2, the ethylene glycol concentration is 10%, and the oxidation time is 60 min, the film has the best corrosion protection, mechanical properties and surface morphology. The resistivity of the samples is about 13 orders magnitude than that of the matrix. Originality/value In this paper, a protective electrically insulating film was prepared by anodic oxidation in an alkaline electrolyte solution. The oxidation conditions were optimized and the oxidation mechanism was analyzed.
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43

Hsieh, Chi-Hsiang, Che-Yuan Chang, Yi-Kai Hsiao, Chao-Chang A. Chen, Chang-Ching Tu, and Hao-Chung Kuo. "Recent Advances In Silicon Carbide Chemical Mechanical Polishing Technologies." Micromachines 13, no. 10 (October 16, 2022): 1752. http://dx.doi.org/10.3390/mi13101752.

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Chemical mechanical polishing (CMP) is a well-known technology that can produce surfaces with outstanding global planarization without subsurface damage. A good CMP process for Silicon Carbide (SiC) requires a balanced interaction between SiC surface oxidation and the oxide layer removal. The oxidants in the CMP slurry control the surface oxidation efficiency, while the polishing mechanical force comes from the abrasive particles in the CMP slurry and the pad asperity, which is attributed to the unique pad structure and diamond conditioning. To date, to obtain a high-quality as-CMP SiC wafer, the material removal rate (MRR) of SiC is only a few micrometers per hour, which leads to significantly high operation costs. In comparison, conventional Si CMP has the MRR of a few micrometers per minute. To increase the MRR, improving the oxidation efficiency of SiC is essential. The higher oxidation efficiency enables the higher mechanical forces, leading to a higher MRR with better surface quality. However, the disparity on the Si-face and C-face surfaces of 4H- or 6H-SiC wafers greatly increases the CMP design complexity. On the other hand, integrating hybrid energies into the CMP system has proven to be an effective approach to enhance oxidation efficiency. In this review paper, the SiC wafering steps and their purposes are discussed. A comparison among the three configurations of SiC CMP currently used in the industry is made. Moreover, recent advances in CMP and hybrid CMP technologies, such as Tribo-CMP, electro-CMP (ECMP), Fenton-ECMP, ultrasonic-ECMP, photocatalytic CMP (PCMP), sulfate-PCMP, gas-PCMP and Fenton-PCMP are reviewed, with emphasis on their oxidation behaviors and polishing performance. Finally, we raise the importance of post-CMP cleaning and make a summary of the various SiC CMP technologies discussed in this work.
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44

Rad, Farhad Yousefi, Michael D. Elwardany, Cassie Castorena, and Y. Richard Kim. "Evaluation of Chemical and Rheological Aging Indices to Track Oxidative Aging of Asphalt Mixtures." Transportation Research Record: Journal of the Transportation Research Board 2672, no. 28 (June 29, 2018): 349–58. http://dx.doi.org/10.1177/0361198118784138.

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Oxidative age hardening in asphalt binder leads to embrittlement. Embrittled asphalt is prone to fatigue and thermal cracking. Therefore, the ability to predict asphalt binder oxidative age hardening within a pavement throughout its service life could inform improved pavement material selection, design, and maintenance practices. Studying the evolution of oxidative aging requires the use of key properties to track oxidation levels, termed aging index properties (AIPs) here. The objective of this study is to identify suitable rheological and chemical AIPs to track oxidation levels in asphalt materials. A wide range of laboratory and field aged materials were evaluated in this study. A range of chemical AIPs determined by Fourier transform infrared spectroscopy (FTIR) absorbance peaks and areas were evaluated based on their correlation with laboratory aging duration. Rheological AIPs were evaluated based on the strength of their relationship to the chemical changes induced by oxidation. The rheological AIPs evaluated included the dynamic shear modulus, zero shear viscosity, Glover-Rowe parameter, and crossover modulus. The chemical AIP evaluation that most strongly correlated with laboratory aging duration is the carbonyl plus the sulfoxide absorbance peaks. The results indicate that both the dynamic shear modulus and Glover-Rowe parameter constitute rheological AIPs that relate directly to the chemical changes induced by oxidation.
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45

Tomar, P. "Material energy balance at articular cartilage: Bio-tribology." IOP Conference Series: Materials Science and Engineering 1254, no. 1 (September 1, 2022): 012042. http://dx.doi.org/10.1088/1757-899x/1254/1/012042.

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Abstract The synergy of heterogeneous macromolecules at the cartilage-cartilage tribological interface prevents friction under quasi-static mechanical loading. Viscoelastic rheology of soft biological membrane materials, hydration lubrication, and biomechanical diffusion integrate boundary lubrication at the superficial zone. Synchronization of mechanical efficiency is viable in alignment with mechanical work, energy expenditure, and reducing oxidative stress of environmental load in urban areas. Carbon nanoparticle’s evolution from anthropogenic activities inversely influence the quality of fuel oxidation. Anisotropic fibrous honeycomb structure panel is included for trapping random environmental carbon nanoparticles/particulate matter for favourable environmental indicators.
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46

Singh Raman, R. K. "Mechanical Alloying of Elemental Powders into Nanocrystalline (NC) Fe-Cr Alloys: Remarkable Oxidation Resistance of NC Alloys." Metals 11, no. 5 (April 23, 2021): 695. http://dx.doi.org/10.3390/met11050695.

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Mechanical alloying is among the few cost effective techniques for synthesizing nanocrystalline alloy powders. This article reviews mechanical alloying or ball-milling of (NC) powders of Fe-Cr alloys of different compositions, and the remarkable oxidation resistance of the NC alloy. The article also reviews challenges in thermal processing of the mechanically alloyed powders (such as compaction into monolithic mass) and means to overcome the challenges.
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47

Tappi, Silvia, Ana Cristina De Aguiar Saldanha Pinheiro, Dario Mercatante, Gianfranco Picone, Francesca Soglia, Maria Teresa Rodriguez-Estrada, Massimiliano Petracci, Francesco Capozzi, and Pietro Rocculi. "Quality Changes during Frozen Storage of Mechanical-Separated Flesh Obtained from an Underutilized Crustacean." Foods 9, no. 10 (October 17, 2020): 1485. http://dx.doi.org/10.3390/foods9101485.

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Despite their high nutritional value, high quantities of fish caught in the Adriatic Sea are underused or discarded for their insignificant economic value. Mechanical separation of flesh represents an opportunity for developing innovative semi-finished products, even if it can promote an increased quality degradation rate. The aim of this study was to evaluate physico-chemical modifications of mechanically separated mantis shrimp flesh during deep-freezing storage. Flesh samples obtained using a belt-drum separator, frozen and vacuum-packed, were stored at 3 temperatures (industrial: −26 °C; domestic: −18 °C and abuse: −10 °C) for 12 months. During storage, qualitative (color, water content, pH, fatty acids (FA) and lipid oxidation) were evaluated. Fish freshness parameters (e.g., trimethylamine (TMA), dimethylamine (DMA) and amino acids) were assessed using nuclear magnetic resonance (1H-NMR). The mechanical separation process accelerated the initial oxidation phenomena, promoting color alterations, compared to manual separation. The main degradation phenomena during storage were significantly affected by temperature and were related to changes in luminosity, oxidation of n-3 polyunsaturated fatty acids (PUFA), increased lipolysis with release of free FA, production of TMA and DMA by residual enzymatic activity, and changes in amino acids due to proteolysis. The inter-disciplinary approach permitted important findings to be made, in terms of the extent of different degradative phenomena, bound to processing and storage conditions of mechanically separated mantis flesh.
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48

Shimanoe, Hiroki, Seunghyun Ko, Young-Pyo Jeon, Koji Nakabayashi, Jin Miyawaki, and Seong-Ho Yoon. "Shortening Stabilization Time Using Pressurized Air Flow in Manufacturing Mesophase Pitch-Based Carbon Fiber." Polymers 11, no. 12 (November 20, 2019): 1911. http://dx.doi.org/10.3390/polym11121911.

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Oxidation–stabilization using pressurized air flows of 0.5 and 1.0 MPa could successfully shorten the total stabilization time to less than 60 min for manufacturing mesophase pitch-based carbon fibers without deteriorating mechanical performance. Notably, the carbonized fiber heat-treated at 1000 °C for 30 min, which was oxidative–stabilized at 260 °C without soaking time with a heating rate of 2.0 °C/min using 100 mL/min of pressurized air flow of 0.5 MPa (total stabilization time: 55 min), showed excellent tensile strength and Young′s modulus of 3.4 and 177 GPa, respectively, which were higher than those of carbonized fiber oxidation–stabilized at 270 °C without soaking time with a heating rate of 0.5 °C/min using 100 mL/min of atmospheric air flow (total stabilization time: 300 min). Activation energies for oxidation reactions in stabilization using pressurized air flows were much lower than those of oxidation reactions using atmospheric air flow because of the higher oxidation diffusion from the outer surface into the center part of pitch fibers for the use of the pressurized air flows of 0.5 and 1.0 MPa than the atmospheric one. The higher oxygen diffusivities resulted in a more homogeneous distribution of oxygen weight uptake across the transverse section of mesophase pitch fibers, and allowed the improvement of the mechanical properties.
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49

Kawada, Tatsuya. "(Invited) Chemo-Mechanical Coupling Phenomena in Solid Oxide Fuel Cells." ECS Meeting Abstracts MA2018-01, no. 32 (April 13, 2018): 1930. http://dx.doi.org/10.1149/ma2018-01/32/1930.

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The materials and the structure of solid oxide fuel cells are designed to avoid thermo-mechanical damages under various operation conditions. However, inherent risk of chemo-mechanical failures are still not fully understood. This paper aims to review the recent works related to this topic, and to address some issues which have not been widely recognized. The coupling of chemistry and mechanics are classified into four types, i.e. (1) chemically driven strain, (2) chemically modified mechanical properties, (3) mechanically driven chemical reactions, and (4) mechanically modified chemical (physical) properties. Since chemical energies are much larger than mechanical energy accommodated in SOFC, the former two types (type(1) and (2)) of chemo-mechanical coupling have been recognized as more important than the others, and have been studied intensively. An example of type-1 phenomena is chemical expansion of mixed conducting oxides with e.g. (La,Sr)(Co,Fe)O3 cathode, LaCrO3 based interconnect, and CeO2 based or (La,Sr)(Ga,Mg,Co)O3 electrolytes. Since the transient behavior as well as steady state distribution of oxygen potential inside the constituent solids is essential to know the effect of the chemical strain, Terada et al. developed a computer code “SIMUDEL” of an FEM-based calculation of oxygen potential. This code considers “chemical capacitance” due to nonstoichiometry of the materials to treat the transient responses, and the results of the calculation can be transported into some of major commercial programs for structure analysis. Volume change of a nickel cermet anode is also an important feature of type-1 coupling which must be considered in determining fabrication and operation processes. The electrode shrinks on reduction and expands on re-oxidation as expected from the lattice size of the metal and the oxide. However, under certain conditions, a porous cermet was found to “shrink” upon oxidation. It took place only during light re-oxidation around 400C. Under this condition the formation of NiO was not obvious from XRD, whereas weight gain was observed by thermo-gravimetry. Careful observation of the microstructure of a porous Ni revealed that, upon shrinkage, the particle-to-particle separation changed partly due to the neck growth between the particles and to the change of the connection angle of the particles. Further study is underway to elucidate the detailed mechanism of the oxidation-induced shrinkage. The change of mechanical properties such as elastic moduli and fracture strength are also dependent on defect concentration and its motion in the lattice (type-2 coupling). Young’s modulus of nonstoichiometric oxides show dependences not only on temperature but also on pO2 through the change of defect concentration. Also, domain boundary shift of ferroelastic phase of LSCF was found to be correlated with the defect concentration. As is discussed for the anomaly of Young’s modulus of YSZ around 400˚C, the motion of oxide ion vacancies may also have correlation with the ferroelastic strain observed with Sc and Ce doped ZrO2 electrolyte above 300˚C. Another interesting type-2 coupling is with the lightly oxidized Ni cermet electrode. It was found that the creep rate of Ni-YSZ cermet at 400˚C was dramatically increased when oxygen-containing gas was introduced. This may be by a correlated mechanism with the above mentioned oxidation induced shrinkage. Several reports, including those from our group, have been published on the effect of mechanical stress on defect formation (type-3 coupling) of nonstoichiometric oxides determined by experiments or by calculation. As is expected from thermodynamic consideration, the experimentally determined effect was not large, e.g. 1G Pa stress was equivalent to 1/5 order of magnitude shift of chemical potential of oxygen for nonstoichiometry of LSCF. Similarly, only minor effect on a practical system was reported for type-4 coupling. However, those phenomena can have significant effect on long-term stability if cation mobility and their driving force are modified at a strained interfaces or grain boundaries.
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50

Li, Dao-Hang, De-Guang Shang, Jin Cui, Luo-Jin Li, Ling-Wan Wang, Cheng-Cheng Zhang, and Bo Chen. "Fatigue–oxidation–creep damage model under axial-torsional thermo-mechanical loading." International Journal of Damage Mechanics 29, no. 5 (November 19, 2019): 810–30. http://dx.doi.org/10.1177/1056789519887217.

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A fatigue–oxidation–creep damage model that can take into account the effect of multiaxial cyclic feature on the damage mechanism is proposed under axial-torsional thermo-mechanical fatigue loading. In the proposed model, the effects of non-proportional additional hardening on fatigue, oxidation, and creep damages are considered, and the variation of oxidation damage under different high temperature loading conditions is also described. Moreover, the intergranular creep damage needs to be equivalent to the transgranular damage before accumulating with the fatigue and oxidation damages. The fatigue, oxidation, and creep damages can be expressed as the fractions of fatigue life, critical crack length, and creep rupture time, respectively, which allows the linear accumulation of different types of damages on the basis of life fraction rule. In addition, the proposed model is validated by various fatigue experimental results, including uniaxial thermo-mechanical fatigue, axial-torsional thermo-mechanical fatigue, and isothermal axial-torsional fatigue under proportional and non-proportional loadings. The results showed that the errors are within a factor of 2.
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