Articoli di riviste: "Electron heat engine"

1

Ding, Zemin, Lingen Chen e Fengrui Sun. "Ecological optimization of energy selective electron (ESE) heat engine". Applied Mathematical Modelling 35, n. 1 (gennaio 2011): 276–84. http://dx.doi.org/10.1016/j.apm.2010.06.003.

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ZHANG, YAN-CHAO, JI-ZHOU HE, YU-LING XIAO e HONG-NI LIANG. "A NANOTHERMOELECTRIC HEAT ENGINE WORKING WITH TWO-LEVEL QUANTUM SYSTEM". Modern Physics Letters B 28, n. 03 (23 gennaio 2014): 1450018. http://dx.doi.org/10.1142/s0217984914500183.

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In this paper, we establish a nanothermoelectric engine consisting of two discrete energy levels embedded between two reservoirs at different temperatures and chemical potentials. Based on master equation, the expressions for the power output and efficiency of the nanothermoelectric engine are derived. The characteristic curves between the power output and the efficiency are plotted. Moreover, the optimal performance parameters are obtained by the numerical calculation. The influence of the strength of variations in electron–electron interactions on the optimal performance parameters is analyzed in detail.

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Wang, HaiLong, Hui Pan e RongMing Wang. "Quantum heat engine cycle working with a strongly correlated electron system". Science China Physics, Mechanics and Astronomy 55, n. 5 (16 marzo 2012): 792–97. http://dx.doi.org/10.1007/s11433-012-4678-9.

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Su, Shanhe, Juncheng Guo, Guozhen Su e Jincan Chen. "Performance optimum analysis and load matching of an energy selective electron heat engine". Energy 44, n. 1 (agosto 2012): 570–75. http://dx.doi.org/10.1016/j.energy.2012.05.044.

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Ding, ZeMin, LinGen Chen, YanLin Ge e ZhiHui Xie. "Optimal performance regions of an irreversible energy selective electron heat engine with double resonances". Science China Technological Sciences 62, n. 3 (10 dicembre 2018): 397–405. http://dx.doi.org/10.1007/s11431-018-9357-5.

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Strangman, T. E., e J. L. Schienle. "Tailoring Zirconia Coatings for Performance in a Marine Gas Turbine Environment". Journal of Engineering for Gas Turbines and Power 112, n. 4 (1 ottobre 1990): 531–35. http://dx.doi.org/10.1115/1.2906200.

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Zirconia coatings represent an advanced materials technology that offers significant durability and performance benefits for marine gas turbines. Thin zirconia coatings offer superior resistance to hot corrosion attack from fuel (sulfur, vanadium, and sodium) and air (sea salt) impurities present in marine engine environments. Thicker zirconia coatings reduce transient thermal stresses and heat transferred into air-cooled components. This paper describes the development of zirconia coatings, applied by the electron beam evaporation-physical vapor deposition process, that are tailored to provide superior durability in a marine engine environment.

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Huang, Jiang Lin, Jean Christophe Gebelin, Richard Turner e Roger C. Reed. "A Process Model for Electron Beam Welding with Variable Thickness". Materials Science Forum 762 (luglio 2013): 538–43. http://dx.doi.org/10.4028/www.scientific.net/msf.762.538.

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A process model for electron beam (EB) welding with a variable thickness weld joint has been developed. Based on theoretical aspects and experimental calibration of electron beam focusing, welding parameters including beam power, focus current, working distance and welding speed were formulated in the heat source model. The model has been applied for the simulation of assembly of components in a gas turbine engine compressor. A series of metallographic weld sections with different welding thickness were investigated to validate the predicted thermal results. The workpieces were scanned both prior to-and after welding, using automated optical metrology (GOM scanning) in order to measure the distortion induced in the welding process. The measured result was compared with predicted displacement. This work demonstrates the attempts to improve the EB welding process modelling by connecting the heat input directly from the actual welding parameters, which could potentially reduce (or even remove) the need for weld bead calibrations from experimental observation.

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Ding, Zemin, Lingen Chen e Fengrui Sun. "Performance optimization of a total momentum filtered energy selective electron (ESE) heat engine with double resonances". Mathematical and Computer Modelling 54, n. 9-10 (novembre 2011): 2064–76. http://dx.doi.org/10.1016/j.mcm.2011.05.015.

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Ding, ZeMin, LinGen Chen e FengRui Sun. "Modeling and performance analysis of energy selective electron (ESE) engine with heat leakage and transmission probability". Science China Physics, Mechanics and Astronomy 54, n. 11 (12 settembre 2011): 1925–36. http://dx.doi.org/10.1007/s11433-011-4473-z.

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Yu, Youhong, Zemin Ding, Lingen Chen, Wenhua Wang e Fengrui Sun. "Power and efficiency optimization for an energy selective electron heat engine with double-resonance energy filter". Energy 107 (luglio 2016): 287–94. http://dx.doi.org/10.1016/j.energy.2016.04.006.

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Cai, Kun, Zhen Zhang, Na Wang, Yu Hu e Fengshan Wang. "Effect of the MoSi2 coating on operational reliability of bipropellant rocket engine". E3S Web of Conferences 260 (2021): 03003. http://dx.doi.org/10.1051/e3sconf/202126003003.

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This present study investigated the MoSi2 coating and its effect on reliability of bipropellant rocket engine. This coating is developed to protect the chamber substrate material form oxidization under hightemperature oxidative circumstance as bipropellant engine works. The multilayer structure of the MoSi2 coating shows excellent high-temperature and thermal-cycle resistance. Its characteristic of self-healing leads to the good performance under the long-time steady working condition for rocket engines. A 25000-seconds firing test was conducted to testify the performance of MoSi2 coating under high temperature above 1400℃. In addition, the influence of coating surface morphology on liquid film cooling was fully discussed in experiment and simulation. High-speed microscopy camera was used to study the effects of Weber number on the spreading and lasting of cooling liquid-film. the simulative comparison was conducted by OpenFOAM to present different transfer-heat modes, when a droplet impinges on the high-temperature surface of MoSi2 coating. All results show that higher smoothness of the coating is suitable for liquid-film cooling, strengthening liquid film spread and heat transfer. Moreover, scanning electron microscope (SEM) was used to study the effect of Mo layer residue on the coating thermal-cycle profermance. The test results indicates that Mo layer residue significantly cause penetrating cracks of the coating and then weaken the self-healing of the coating at downstream of throat. Therefore, it is important to strictly control the thickness of Mo layer by means of matching Mo target in ion plating. Thus after properly prolonging the infiltration time, Mo layer can be silicified completely without residue.

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Zhu, Dongming, e Robert A. Miller. "Thermal-Barrier Coatings for Advanced Gas-Turbine Engines". MRS Bulletin 25, n. 7 (luglio 2000): 43–47. http://dx.doi.org/10.1557/mrs2000.123.

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Ceramic thermal-barrier coatings (TBCs) have received increasing attention for gasturbine engine applications. The advantages of using TBCs include increased fuel efficiency by allowing higher gas temperatures and improved durability and reliability from lower component temperatures. As illustrated in Figure 1, TBCs can provide effective heat insulation to engine components, thus allowing higher operating temperatures and reduced cooling requirements. Atypical two-layer TBC system consists of a porous ZrO2-Y2O3 ceramic top coat and an oxidation-resistant metallic bond coat. These TBC systems can be applied to the metal substrate either by plasma spray or by electron-beam physical vapor deposition (EB-PVD) techniques.

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Luo, Xiaoguang, Jizhou He, Kailin Long, Jun Wang, Nian Liu e Teng Qiu. "A theoretical study on the performances of thermoelectric heat engine and refrigerator with two-dimensional electron reservoirs". Journal of Applied Physics 115, n. 24 (28 giugno 2014): 244306. http://dx.doi.org/10.1063/1.4885295.

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Markovsky, Pavlo E. "Application of Local Rapid Heat Treatment for Improvement of Microstructure and Mechanical Properties of Titanium Products". Key Engineering Materials 436 (maggio 2010): 185–94. http://dx.doi.org/10.4028/www.scientific.net/kem.436.185.

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Local Rapid Heat Treatment (LRHT) based on induction-heating methods can be used to form unique location-specific microstructures and properties in commercial titanium alloys while maintaining the bulk of the material in an initial, non-heat-treated condition. The present work is focused on practical aspects of LRHT application for microstructure/ mechanical properties improvement of some parts made of commercial titanium alloys. It is shown, that LRHT application could improve mechanical properties of such complicated part like turbine engine compressor blades, and two made of Ti-6Al-4V and VT22 titanium alloys goods after repair with Electron Beam Physical Vapor Deposition as well as with Build-up Welding.

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Saikawa, Seiji, Manabu Mizutani e Nozomu Kawabe. "Effect of Sn Content on Heat Resistance of Mg-3%Al-1%Si Alloy for Casting". Materials Science Forum 941 (dicembre 2018): 1071–76. http://dx.doi.org/10.4028/www.scientific.net/msf.941.1071.

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Magnesium alloys have the characteristic with high specific strength and lightweight property, it is widely used for auto mobile industry. Heat-resistant magnesium alloy is focused as a suitable material for weight reduction of the engine and power train parts in automotive field. In this study, microstructure and heat-resistant property in Mg-3mass%Al-1mass%Si (Mg-3%Al-1%Si) alloy with containing large amount of Sn (tin) were investigated. The alloys produced by permanent mold casting were investigated by optical microscope (OM), scanning electron microscopy (SEM) and measuring of bolt load retention at 423K. The heat-resistant property of Mg-3mass % Al-1mass % Si alloy with containing 6-13masss%Sn was higher compared with Sn free alloy and conventional Magnesium alloys (e.g. AZ91 and AM60 alloys).

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Reed, R. C., H. J. Stone, S. M. Roberts e J. M. Robinson. "The development and validation of a model for the electron beam welding of aero-engine components". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 211, n. 6 (1 giugno 1997): 421–28. http://dx.doi.org/10.1243/0954410971532785.

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Electron beam welding is used to manufacture high-integrity structures, for example compressor assemblies, for the latest generation of Rolls-Royce aero-engines. For such applications, the welding variables (for example welding current, voltage, beam focusing parameters) must be optimized, such that any distortion induced by the process is insignificant when compared to the dimensional tolerances allowed by the designers. Furthermore, the residual stresses induced by the process must be described and characterized, since these are required for estimates of component life. A model for such electron beam welding processes is described, along with the strategy adopted during its development. The basis of the model is a coupled thermal-mechanical finite element analysis. Particular attention is paid to (a) modelling of the heat source, (b) the frame of reference for the analysis, and (c) choice of finite element mesh. For the purposes of calibration and verification, a number of validatory experiments have been carried out. Typical results are presented and practical benefits are discussed.

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Qi, Hong Yu, Jian Xie, Shao Lin Li e Xiao Guang Yang. "Mechanical Properties of Forged Ti-6Al-4V Structure by Electron Beam Welding". Advanced Materials Research 455-456 (gennaio 2012): 308–13. http://dx.doi.org/10.4028/www.scientific.net/amr.455-456.308.

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The blisk (bladed disk) is a new structural component of the modern aero-engine and plays an important role in improving its performance. Ti-6Al-4V alloy joints welded by electron beam have been widely used for compressor blisk in advanced aero engine. It is necessary to analyze microstructure and mechanical properties of Ti-6Al-4V welded structure by electron beam welding (EBW) for failure analysis and structure design of blisk. Microstructure of Ti-6Al-4V welded structure by EBW was investigated by microscopic observation and micro indentation testing. Experiment results show grain coarsening in fusion zone (FZ) and heat affected zone (HAZ) appears large gradient organization structure, which presents significant local heterogeneity. On the centerline perpendicular to the welding direction, Vickers microhardness was measured in increments of 1mm, 0.5mm, 0.25mm and 0.1mm. Due to the presence of martensite, microhardness of the fusion zone is about 20% higher than that of the base material. The size of joints in different regions was acquired, 2.5 to 3.0-mm-wide in FZ and about 0.7-mm-wide in HAZ respectively. Three different types of EBW samples were designed for tensile test, including welded structure, welded joint and base material. Three different stress-strain curves of specimens were acquired, including welded joint. The experiment data indicates that the tensile strength of welded joints is 8% more than that of the base metal.

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Urbahs, Alexanders, e Konstantins Savkovs. "Features of Creating Nanostructured Intermetallic T_i-Al-S_i-C_r Coatings for the Hot Section Part of Gas Turbine Engines". Key Engineering Materials 799 (aprile 2019): 52–58. http://dx.doi.org/10.4028/www.scientific.net/kem.799.52.

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The paper deals with the results of a research study into Ti-Al-Si-Cr-based thin heat resistant ion-plasma coatings for titan alloy-based parts of a gas turbine engine (GTE). The research involved the use of three Ti-Al-Si-Cr-based alloys – intermetallic, with different Cr-Ti priority. The analysis of surface oxidation process in the range of 600-850°C with the help of scanning electron microscopy was performed, and the key features of coating fracture process under high-temperature oxidation conditions were identified.

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Xiao, Min, Cheung Poon, Priti Wanjara, Mohammad Jahazi, Zouheir Fawaz e P. Krimbalis. "Optimization of Nd:YAG-Laser Welding Process for Inconel 718 Alloy". Materials Science Forum 546-549 (maggio 2007): 1305–8. http://dx.doi.org/10.4028/www.scientific.net/msf.546-549.1305.

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Ni-based superalloys are extensively used in the manufacture of aircraft engine components because of their excellent heat-resistant and corrosion-resistant properties. The principal joining processes for Ni-based superalloys are TIG welding, MIG welding, submerged arc welding, electron beam welding, and CO2 laser welding. In this investigation, a robotic 4-kW continuous-wave Nd:YAG laser system was used to identify the optimal laser welding process for 2.0 mm thick Inconel (IN) 718 sheets. The effect of various processing parameters, which included power input, welding speed, weld geometry and filler wire, was studied using the Taguchi design of experiment (DOE) methodology. The DOE methodology enabled the evaluation of the relationship between the process parameters and the quality of the welded joints, from which the optimal Nd:YAG laser welding process was developed for IN718 alloy. Joint quality was examined by tensile and nondestructive testing methods. Using the optimal process established in this research, mechanically-sound welds with narrow fusion and heat-affected zones were produced. The outcome of this research demonstrates the feasibility of the application of Nd:YAG laser in the joining of IN718 sheets for the manufacture of aircraft engine components.

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Luo, Xiaoguang, Cong Li, Nian Liu, Ruiwen Li, Jizhou He e Teng Qiu. "The impact of energy spectrum width in the energy selective electron low-temperature thermionic heat engine at maximum power". Physics Letters A 377, n. 25-27 (ottobre 2013): 1566–70. http://dx.doi.org/10.1016/j.physleta.2013.04.045.

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Dong, Jun, Weili Wang, Xiaofeng Wang, Shaojun Qiu, Maohua Du, Bo Tan, Yanjing Yang e Taizhong Huang. "Influences of Multilayer Graphene and Boron Decoration on the Structure and Combustion Heat of Al3Mg2 Alloy". Nanomaterials 10, n. 10 (13 ottobre 2020): 2013. http://dx.doi.org/10.3390/nano10102013.

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To improve the engine-driven performance of propellants, high-energy alloys such as Al and Mg are usually adopted as annexing agents. However, there is still room for improvement in the potential full utilization of alloy energy. In this study, we investigated how to improve combustion efficiency by decorating Al3Mg2 alloy with multilayer graphene and amorphous boron. Scanning electron microscopy and Raman tests showed that decorating with multilayer graphene and amorphous boron promoted the dispersion of Al3Mg2 alloy. The results showed that decorating with 1% boron and 2% multilayer graphene improved the combustion heat of Al3Mg2 alloy to 32.8 and 30.5 MJ/kg, respectively. The coexistence of two phases improved the combustion efficiency of the matrix Al3Mg2 alloy.

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Papadimitriou, Ioannis, Claire Utton e Panos Tsakiropoulos. "Phase Equilibria in the Nb-Rich Region of Al-Nb-Sn at 900 and 1200 °C". Materials 12, n. 17 (28 agosto 2019): 2759. http://dx.doi.org/10.3390/ma12172759.

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The Al-Nb-Sn phase diagram was studied experimentally in the Nb-rich region to provide important phase equilibria information for alloy design of Nb-silicide based materials for aero engine applications. Three alloys were produced: Nb-17Al-17Sn, Nb-33Al-13Sn and Nb-16Al-20Sn (at.%). As-cast and heat-treated alloys (900 and 1200 °C) were analysed using XRD (X-ray diffraction) and SEM/EDS (scanning electron microscopy/ electron dispersive x-ray spectroscopy). Tin showed a high solubility in Nb2Al, reaching up to 21 at.% in the Sn-rich areas, substituting for Al atoms. Tin and Al also substituted for each other in the A15 phases (Nb3Al and Nb3Sn). Tin showed limited solubility in NbAl3, not exceeding 3.6 at.% as it substituted Al atoms. The solubility of Al in NbSn2 varied from 4.8 to 6.8 at.%. A ternary phase, Nb5Sn2Al with the tI32 W5Si3 crystal structure, was found to be stable. This phase was observed in the 900 °C heat-treated samples, but not in the 1200 °C heated samples.

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Sakthinathan, Ganapathy, Raju Saravanan e Chandrasekaran Uthirapathy. "Thermal characteristics of yttria stabilized zirconia nanolubricants". Thermal Science 16, n. 2 (2012): 481–87. http://dx.doi.org/10.2298/tsci1202481s.

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The transition from microparticles to nanoparticles can lead to a number of changes in its properties. The objective of this work is to analyze the thermal, tribological properties of yttria stabilized zirconia nanoparticles. Nanosized yttria stabilized zir conia particles were prepared by milling the yttria stabilized zirconia (10 ftm) in a planetary ball mill equipped with vials using tungsten carbide balls. After 40 hours milled the yttria stabilized zirconia nanoparticles of sizes ranging from 70-90 nm were obtained. The phase composition and morphologies of the assynthesized particles were characterized by energy dispersive X-ray analysis, scanning electron microscope, transmission electron microscope, thermogravimetric analysis and differential scanning calorimeter, and the images of the same were obtained. From TG-DSC analysis it was confirmed that, the yttria stabilized zirconia nanoparticles were heat stable under different thermal conditions which is due to the addition of yttria to pure zirconia. Due to this property of yttria stabilized zirconia nanoparticles, it can be widely used in high transfer application such as lubricant additives. The heat transfer properties of automotive engine lubricants were determined by utilization of measured thermal conductivity, viscosity index, density, flash point, fire point and pour point revealed that lubricants with additive constituents have a significant effect on the resultant heat transfer characteristics of the lubricants.

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Wei, Li Jun, Bo Long Li, Liu Yi Guan, Tong Bo Wang, Peng Qi e Zuo Ren Nie. "Influence of Die Casting Temperature and T1 Treatment on the Microstructure and Properties of the Alsicumg Alloy". Materials Science Forum 877 (novembre 2016): 127–31. http://dx.doi.org/10.4028/www.scientific.net/msf.877.127.

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Al-Si alloy was widely applied in automobile engine parts to realize weight reduction. The influence of casting temperature on the microstructure of die casting Al-Si-Cu-Mg alloy was studied in this paper. Based on ZL 101 alloy, the strength was improved with addition of 0.8% Cu element. The influence of pouring temperature on microstructure was investigated using optical microscope and electron probe micro-analysis (EPMA), and T1 heat treatment was optimized. The primary α-Al was more coarsened when the pouring temperature rose from 660 ̊C to 690 ̊C. The solid solubility of Cu in α-Al was 0.2406 wt%, analyzed by EPMA. Considering the solid solubility of Cu and avoiding porosity at high-temperature, T1 heat treatment was reasonable and affective. The micro-hardness reached to a peak value of 114 HV during aging at a temperature of 175 ̊C after 10 h. Therefore, 175 ̊C×10h aging was the most appropriate heat treatment process.

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Monteiro, Waldemar A., e Ingrid A. Dos Santos. "Microstructural evolution of a nickel-based superalloy". Proceedings, annual meeting, Electron Microscopy Society of America 48, n. 4 (agosto 1990): 936–37. http://dx.doi.org/10.1017/s0424820100177817.

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Superalloys are indispensable for the superior perfomance and efficien of jet engine turbine disks,turbine blades,combustors,roket shells and many other devices and components used in various industries, in Cluding nuclear, space and aeronautics.Over the last thirty years,nickel-base superalloys has undergone more structural studies than any other superalloy as a result of attempts to correlate its properties to microstructure and heat treatment. To avoid contradictory or inconsistent findings, it is also necessary a carefully microstructural observation of the employed starting materials. In the present paper,we report morphologies relating to the as cast , forged and heat-treated Ni-base superalloy by transmission and scanning electron microscopy. This superalloy contain intermettallic compounds and carbides. The alloy in study was an as cast and also forged Ni-Fe based superalloy with the following chemical composition:

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Uzunonat, Yagiz. "Investigation of Impact Behavior of TIG Welded Inconel 718 at Aircraft Engine Operating Temperatures". Materials Science Forum 890 (marzo 2017): 339–43. http://dx.doi.org/10.4028/www.scientific.net/msf.890.339.

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In this work, Charpy notch pendulum impact test was performed on non-welded and TIG (Tungsten Inert Gas) welded Inconel 718 specimens at three different temperatures as 20°C, 500°C and 700°C. After the completion of tests, SEM (Scanning Electron Microscopy) inspection and EDX (Energy-Dispersive X-Ray Spectroscopy) analysis were performed for the microstructural examination of the specimens. Hardness measurements on the rupture zone of selected welded and non-welded specimens were also performed to make a better approach to interpretation of the impact behavior of material. Inspections indicated that hardness values in the heat affected zone of welded specimens dramatically decreased and they displayed higher ductility during fracture than non-welded samples due to partial softening of structure. The reason of further decrease in impact resistance of welded specimens was explained as the precipitation and coarsening of γ′′ and carbide phases in the interdendritic regions with increasing temperature.

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Chmiela, B., B. Kościelniak e J. Cwajna. "Effect of hot isostatic pressing on the microstructure of turbine blade airfoil made of nickel-base superalloy". Archives of Metallurgy and Materials 62, n. 1 (1 marzo 2017): 241–45. http://dx.doi.org/10.1515/amm-2017-0036.

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Abstract Turbine blades are flight safety parts in the jet engine. Therefore they should be characterized by very good mechanical properties, especially high creep resistance and fatigue strength at high temperature. The mechanical properties of blades made of nickel-based superalloys depend on the microstructure of the casting and its porosity [1,2]. The aim of this paper is evaluation of effect of hot isostatic pressing (HIP) on microstructure of blade airfoil made of IN713C superalloy in four important zones: (i) leading edge, (ii) trailing edge, (iii) suction side and (iv) pressure side. HIP treatment was carried out proving some significant microstructural changes. Electron backscatter diffraction (EBSD) analysis reveals some structural changes what may facilitate diffusion processes leading to simplify of a heat treatment (solution treatment and aging).

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Park, K., e C. Sung. "Characterization of SiC fiber-reinforced SiC composites by TEM". Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 632–33. http://dx.doi.org/10.1017/s042482010017089x.

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SiC fiber-reinforced SiC composites have been accepted to have considerable potential as an engineering structural ceramic for numerous high-temperature applications, such as various heat engine components. In this study, the microstructure of matrix, fiber, and matrix/fiber interface of SiC fiber (SCS-6, Textron)-reinforced nitrogen-treated SiC composites was characterized using transmission electron microscopy (TEM). Cross-sectional TEM samples were prepared by mechanical grinding, dimpling, and ion-milling. The samples were analyzed using a Philips EM400T TEM and a Noran ultrathin window Micro-Z detector.The α-Si3N4 was formed in the porous SiC matrix by nitriding (Fig. 1(a)). The porous SiC matrix can permit easy and continuous penetration of the nitriding gas and rapid escape of the reaction and volatilization products, thus favoring vapor-phase reactions. In the case of huge SiC grains, the α-Si3N4 was formed at the surface of the huge SiC grains. Rod-shaped Si2N2O phase was often observed in the porous matrix. Figs. 1(b), (c), and (d) show electron diffraction patterns obtained from the α-SiC, α-Si3N4, Si2N2O phases, respectively.

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Alhummiany, H. "Novel Nanofluid Based on Water-Loaded Delafossite CuAlO2 Nanowires: Structural and Thermal Properties". Journal of Nanomaterials 2018 (2018): 1–6. http://dx.doi.org/10.1155/2018/4076960.

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Ultra-high cooling performance is a crucial requirement of many thermomechanical systems, such as microelectronic devices, engine cooling systems, nuclear power systems, chemical reactors, and refrigeration systems. Recent experimental results reveal the potential thermal properties of suspended nanometallics in conventional fluids. In this study, the facile synthesis of one-dimensional delafossite CuAlO2 nanowires by microwave hydrothermal treatment was presented. A novel type of nanofluid consisting of CuAlO2 nanowires suspended in distilled water at various volume fractions (0.0, 0.2, 0.4, and 0.6 wt%) was successfully synthesized using an easily scalable sonication method. The microstructures of as-synthesized CuAlO2 were investigated by adopting X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and field-emission scanning electron microscopy (FESEM). Furthermore, the thermal conductivity and specific heat capacity of water-loaded nanofluid were measured at different volume fractions and temperatures. The results reveal a significant increase in thermal conductivity with increasing CuAlO2 loading levels and temperatures. The obtained results propound the fact that water-loaded delafossite CuAlO2 nanowires-based nanofluid is a promising candidate for future industrial applications.

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Lu, Yu Heng, Cai Min Huang e Jian Min Zeng. "Diffusion Study of Al-8%Si Alloy Double-Coating on Steel". Advanced Materials Research 189-193 (febbraio 2011): 1080–84. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.1080.

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Al-8%Si alloy double-coating on Q235 steel were produced, Then the samples were executed diffusion at high temperatures protecting with flowing argon gas. Scanning electron microscope (SEM), optical microscope (OM), and energy dispersive X-ray spectroscope (EDS) were employed for microstructure observation of cross-sectional, surface and compositional analysis of coating. The diffusion mathematical model was established with the finite element method. The results show that good quality Al-8%Si coating is made; after heat-diffusion treatment, the new phases FeAl and Fe3Al presents; Silicon atoms in Al-8%Si alloy can hinder the diffusion of aluminum atoms into steel substrate at high temperature; Al-8%Si alloy double-coating sample’s high-temperature oxidation resistance is higher than Q235 steel. This material is hopefully used in the engine exhaust manifold.

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Graboś, Adrian, Jan Huebner, Paweł Rutkowski, Shenghua Zhang, Yen-Ling Kuo, Dariusz Kata e Shigenari Hayashi. "Microstructure and Hardness of Spark Plasma Sintered Inconel 625-NbC Composites for High-Temperature Applications". Materials 14, n. 16 (16 agosto 2021): 4606. http://dx.doi.org/10.3390/ma14164606.

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The study focuses on obtaining Inconel 625-NbC composites for high-temperature applications, e.g., jet engines, waste-to-energy combusting systems or gas engine turbines, and characterizing them in terms of their microstructure and hardness improvement. Synthesis was performed utilizing Spark Plasma Sintering (SPS) at 1150 °C under the load of 45 MPa in medium vacuum (under 10−3 MPa) for a total time of 60 min. Four sets of samples with different Inconel 625 to NbC weight ratios were prepared (5, 10, 20, and 30 wt.%), followed by a reference sample containing no ceramic reinforcement. Obtained materials were hot-rolled at 1150 °C with a 10% reduction step and later cut and polished to perform characterization utilizing scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) module and microhardness testing device equipped with Vickers indenter. Hardness was improved proportionally to NbC addition achieving an increase of up to 20% of reference values. Additional heat treatment was conducted on the hot-rolled samples at 1200 °C in an argon atmosphere to further observe the interaction between reinforcement and alloy. Their microstructure revealed the coarsening of precipitates within the metal matrix and partial reinforcement dissolution, which proved to be crucial to obtaining the highest quality composites with homogenous hardness improvement.

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32

Frutos-Myro, Enrique, Ian MacLaren, Peifeng Li, Iain Berment-Parr e Mathew Thomas. "Nano-scale characterisation of tri-modal microstructures in TIMETAL® 575". MATEC Web of Conferences 321 (2020): 12025. http://dx.doi.org/10.1051/matecconf/202032112025.

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TIMETAL® 575, developed by Titanium Metals Corporation (TIMET), is a high strength forgeable α+β titanium alloy with comparable density, beta transus temperature and processing characteristics to Ti-6Al-4V but with enhanced static and fatigue strength primarily aimed at aero-engine disc or blade applications. Recent research on this alloy has focussed on microstructure evolution as a means to optimise mechanical behaviour and it has been concluded that a solution heat treatment followed by an ageing step yields a resulting “tri-modal” microstructure, consisting of equiaxed primary α and bi-lamellar transformation product containing nano-scale “tertiary alpha” laths, which appear to provide an excellent balance of strength and ductility. The key objective of the work presented here is to characterise this complex nanoscale microstructure in detail at various stages of alloy processing. For that purpose various advanced and recently developed transmission electron microscopy (TEM) techniques have been used. These include alpha and beta phase mapping Precession Electron Diffraction (PED), overall microstructure imaging with conventional BF and DF TEM, distinction of fine phase detail with high angle annular dark field (HAADF) scanning TEM (STEM), and correlation of the nanostructure to the elemental distribution using scanned Electron Energy Loss Spectroscopy (EELS).

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33

Veerasamy Shamprasshaath, Shaisundaram, Chandrasekaran Manoharan, Hemalatha Krishnaraj e Martin Lazar. "Thermal barrier coating using yttria stabilized zirconia by plasma spray technique". Thermal Science, n. 00 (2021): 156. http://dx.doi.org/10.2298/tsci201027156v.

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This paper deals with the tribological behavior of thermal barrier coating in engine liner andit also deals with the quality of thermally treated coating. Multilayer structure formed from topcoat and bond coat which was deposited on the same type of steel substrates, in which heat treatments may improve the mechanical properties of materials both substrate and coating and enhance their hardness for many cases of ceramics through recrystallization of microstructures. In addition, heat treatments will introduce residual stresses by different thermal contractions and lattice misfits because of micro structural changes that could lead to either premature failure or stress relaxation by new crack formations. Tribological wear properties of differently treated thermal barrier coating was examined to see the net effect of heat treatment on mechanical properties by Tribometer with Pin on Disc mode. Indentation test at surface and cross-section of coatings are examined. Scanning Electron Microscope and optical microscope examine several crack propagations. Energy-dispersive X-Ray spectroscopyhelps to characterize thermal barrier coating. After thermally treating the sample, On examination of thermal barrier coating the oxide content was increased, sample became convex due to residual compressive stress, roughness reduces, adhesion between topcoat and bond coat get reduced eventually. In addition to that, the surface gets cracks due to the reduction in hardness from 330 HV to 212 HV.

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Kianicová, Marta, e Jan Kafrik. "A Study of Hot Corrosion Behaviour of NiAl Coatings in an Aggressive Environment". Solid State Phenomena 226 (gennaio 2015): 177–82. http://dx.doi.org/10.4028/www.scientific.net/ssp.226.177.

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The microstructure and corrosion behaviour was studied for a diffusionβ-NiAl and Si modifiedβ-NiAl coatings formed on the superalloy MAR-M 247. First type,β-NiAl coating was applied with the help of method “out-of-pack”. Second type, Si modifiedβ-NiAl coating was applied by method “pack-cementation”. Diffusion coatings created protective, heat-activated layer which separated superalloy from aggressive environment. Corrosive environment was created by tablets Na2SO4at 900°C. Technique of scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDS) was used to characterize the corrosion products. Experiment confirmed the advantages relating to the application of diffusion coating in aggressive environment which imitated environmental condition during operation of turbine engine. This experiment was made in cooperation with company PBS Velká Bíteš a. s., Velká Bíteš, Czech Republic and The Silesian University of Technology, Faculty of Materials Science and Metallurgy, Katowice, Poland.

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35

Barbieri, Giuseppe, Francesco Cognini, Vincenzo Bonaiuto, Roberto Montanari, Maria Richetta e Alessandra Varone. "Laser Beam Welding of IN792 DS Superalloy". Materials Science Forum 941 (dicembre 2018): 1149–54. http://dx.doi.org/10.4028/www.scientific.net/msf.941.1149.

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The main purpose of the investigation is to develop reliable methods to repair IN 792 superalloy components by Laser Beam Welding (LBW). The jet engine structural components made of nickel-base superalloys are subjected to high stresses and severe environmental, therefore crack may occurs during in-service life. Considering the high cost of this components they are often repaired by welding. Welds must be made: (i) by altering as little as possible the original microstructure; (ii) without introducing in the molten (MZ) and heat affected (HAZ) zones relevant residual stresses; (iii) without producing cracks in MZ and HAZ; (iv) without massive chemical segregation; (v) without elemental diffusion changing the composition of g and g’ phases.LBW has been used to realize seams on 2mm-thick plates of directionally solidified (DS) IN792 superalloy. An Yb fiber laser has been employed in present experiments and the molten pool was shielded from oxidation through a patented equipment. A grid of samples has been prepared by varying the pass speed v from 1 to 2.0 m/min with pre-heating temperature of 200 °C. The microstructural changes occurring in the microstructure of molten zone (MZ) and heat affected zone (HAZ) have been investigated by optical and scanning electron microscopy (SEM) observations and energy dispersion spectroscopy (EDS).

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36

Ziaja, Waldemar, Maciej Motyka, Krzysztof Kubiak e Jan Sieniawski. "Cyclic creep behaviour of two-phase Ti-6Al-2Mo-2Cr alloy". MATEC Web of Conferences 321 (2020): 11079. http://dx.doi.org/10.1051/matecconf/202032111079.

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One of the important criteria for selection titanium alloys for discs and blades of turbine engine compressor is their fatigue and creep strength at room and elevated temperature. Fatigue and creep properties of two-phase titanium alloys show strong dependence on microstructure, especially morphology of the α and β phases which can be controlled to certain extent by proper selection of hot working and heat treatment conditions. Quantitative description of two-phase titanium alloys behaviour under loading and environmental conditions leading to combined creep and fatigue processes has been always very challenging task due to large number of factors affecting deformation and fracture behaviour of the material. In the course of the research cyclic creep behaviour of Ti-6Al-2Mo-2Cr alloy (VT3-1) was investigated and compared to low-cycle fatigue and static creep properties at the temperature of 450°C. Microstructure of the alloy was varied by means of the heat treatment. Constant load tensile creep tests were carried out. Tension-tension cyclic loading was applied at the constant stress ratio with and without hold time at maximum load. The effect of test parameters on the creep-fatigue life at elevated temperature was estimated. Characteristic features of fracture surfaces were identified by scanning electron microscopy methods.

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37

Hall, Ernest L., Ann M. Ritter e Nathan Lewis. "Microstructural analysis of fiber coatings and reaction zones in Ti-14Al-21Nb/SiC composites". Proceedings, annual meeting, Electron Microscopy Society of America 48, n. 4 (agosto 1990): 198–99. http://dx.doi.org/10.1017/s0424820100174126.

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Titanium and titanium aluminide fibrous composites are currently under consideration for use in aircraft engine and other applications, and their fabrication, microstructure, and properties are under active investigation. These composites can exhibit enhanced strength relative to the unreinforced matrix alloy, but ductilities are often limited, especially at room temperature. This limited ductility may be related to the formation of brittle reaction zones between the fiber and the matrix during fabrication, heat treatment, or use. In this study, the reaction zones formed during fabrication of a Ti-14 wt. pet. Al-21 wt. pet. Nb (Ti- 142l)/SiC composite were studied using analytical electron microscopy (AEM). The composites were fabricated by plasma-spraying Ti-1421 powder onto a drum wound with SCS-6 SiC fiber obtained from Textron Specialty Materials. The tapes were then stacked and consolidated into 4-ply composites by hot isostatic pressing. After fabrication, samples were prepared for AEM analysis by ion milling.

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38

Özkan, Doğuş, e Cenk Türküz. "Chromium nitride-coated copper beryllium as a cam tappet material candidate". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, n. 15 (21 maggio 2020): 3030–46. http://dx.doi.org/10.1177/0954406220927055.

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Copper beryllium (CuBe) with good mechanical and high electrical conductivity properties is used in metalworking, electronic devices, automotive systems, and aerospace systems. Having low hardness limits its usage in tribosystems such as internal combustion engine valve train systems. In this study, heat-treated CuBe material was coated with CrN under a micron thickness by cathodic arc physical vapor deposition (arc-PVD) to improve wear resistance not only at unlubricated condition but also at the lubricated condition for tribosystem, especially a material candidate for cam tappets. Therefore, CrN-coated CuBe, CuBe, and AISI52100 steel samples were tested by a tribometer at unlubricated and lubricated sliding conditions. Surface morphological changes and tribochemical formation were investigated by optical microscope, optical profilometer, atomic force microscope, and scanning electron microscope. The results showed that CrN increased the wear resistance of the CuBe significantly, and it can be used as cam tappet material both on unlubricated and boundary lubrication regimes.

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39

Swadźba, Lucjan, Ginter Nawrat, Boguslaw Mendala e Marek Goral. "The Influence of Deposition Process on Structure of Platinum-Modifed Aluminide Coatings O Ni-Base Superalloy". Key Engineering Materials 465 (gennaio 2011): 247–50. http://dx.doi.org/10.4028/www.scientific.net/kem.465.247.

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The modern jet engines used in commercial and military aircrafts are characterized by operating temperature in turbine section above 1000oC. The Ni-base superalloy turbine blades and vanes working in high temperature in very aggressive environment require using of protective coatings. The aluminide coatings are widely used to protect this engine parts. The pack cementation, out of pack and chemical vapour deposition (CVD) technologies are usually used to produce this type of coating. The aluminide coatings can be modified by platinum or other elements. The Pt-modified aluminide coatings are characterized by better oxidation and corrosion resistance in comparison with conventional aluminide coatings and can be used as a bond coat for Thermal Barrier Coatings deposited by EB-PVD technology. In present study the influence of deposition technology and their’s parameters on structure and chemical composition of Pt-aluminide coatings are presented. The base material for coatings was a Inconel 738 Ni-base superalloy. The first step of coatings production were Pt electroplating with different thickness of platinum layer. The second step of coating production was aluminising process. The aluminide coatings were produced by pack cementation and out of pack technologies. Additional the influence of heat treatment of base alloy with coatings was investigated. The structure of all deposited coatings was observed by scanning electron microscopy and the chemical and phase composition of coatings were investigated by EDS and XRD methods. The observed coatings were characterized by two types of structure: first based on NiAlPt phase obtained on thin Pt layer and the second with additional presence of PtAl2 phase on the thick Pt layer.

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40

Belan, Juraj, Alan Vaško, Lenka Kuchariková e Eva Tillová. "The fractography analysis of IN718 alloy after three-point flexure fatigue test". MATEC Web of Conferences 157 (2018): 07001. http://dx.doi.org/10.1051/matecconf/201815707001.

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Abstract (sommario):

In this study, the high cycle fatigue (HCF) properties of IN718 superalloy with given chemical composition were investigated at three-point flexure fatigue test at room temperature. INCONEL alloy 718 is nickel-chromium-iron hardenable alloy and due to its unique combination of mechanical properties (high-strength; corrosion-resistant and so on) used for production of heat resistant parts of aero jet engine mostly. Mechanical properties of this alloy are strongly dependent on microstructure and on presence of structural features such are principal strengthening phase gamma double prime, gamma prime and due to its morphology less desired delta phases. The mentioned phases precipitate at various temperature ranges and Nb content as well. The three-point flexure fatigue test was performed on ZWICK/ROELL Amsler 150 HFP 5100 test equipment with approximate loading frequency f=150 Hz. The S – N (Stress – Number of cycles) curve was obtained after testing. With the help of scanning electron microscope (SEM), fractography analyses were performed to disclose the fracture features of specimens in different life ranges. The brief comparison of three-point flexure and push-pull fatigue loading modes and its influence on fatigue life is discussed as well.

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Peng, Li Ming, Bin Hu e Wen Jiang Ding. "Mechanical Properties, Aging Behavior and Microstructure Evolution of Mg-Nd-Zn-Zr Based Magnesium Matrix Composite Reinforced with Alumina Fibers". Materials Science Forum 706-709 (gennaio 2012): 687–92. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.687.

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Abstract (sommario):

Metal matrix composites reinforced with discontinuous reinforcement (short fiber, whisker or particle) are attractive for applications requiring higher stiffness and strength than traditional alloys. Unlike continuously reinforced composites, where the properties are mainly influenced by fibers, the properties of the discontinuously reinforced composites seem to be influenced more by matrix properties. Most of the discontinuously reinforced composites are based on age-hardenable light alloys, so that aging treatments can be applied to develop the optimum properties of the composites. The aging behavior of discontinuously reinforced composites has been a subject of great interest both from scientific and technological view points. Recently developed NZ30K (Mg-3wt.%Nd-0.5wt.%Zn-0.5wt.%Zr) alloys exhibit higher specific strength at both room and elevated temperatures, better strength and creep resistance than the existing commercial magnesium alloys. Accordingly, this alloy can be considered as a candidate material for potential automobile applications, such as engine blocks and pistons, which experience high service temperature. Its use could save considerable mass weight in powertrain systems. However, low elastic modulus and wear resistance of magnesium alloys limit their widespread applications. Metal matrix composites have been proposed as the feasible and economical solution. The aim of this study is to investigate the effect of alumina fibers on the aging hardening kinetics and age-hardening efficiency of squeeze cast NZ30K/Saffil/15p magnesium matrix composite. The aging behavior has been examined using Vickers, combined with microstructure observation developed during heat treatment by optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

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42

Guo, Zi Xu, Xiao Yu Qin, Da Wei Huang e Xiao Jun Yan. "Morphology Evolution and Probability Characteristic of γ' Phase in Single Crystal Superalloy during Creep Rafting". Key Engineering Materials 827 (dicembre 2019): 373–78. http://dx.doi.org/10.4028/www.scientific.net/kem.827.373.

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Abstract (sommario):

Ni-based single crystal (SC) superalloys are widely applied in the turbine blades of advanced aero-engine due to their excellent heat resistance. Rafting is a major degradation mode of SC under creep damage. In this study, the morphology evolution and probability characteristic of shape parameters are investigated for cuboidal γ´ phase during creep rafting. Three groups of SC creep tests are carried out at 850 °C and 600 Mpa along [001] direction. Scanning electron microscope (SEM) is used to observe the microstructure of SC at four different creep times including 0 h, 8 h, 16 h and 64 h. In addition, an image processing program is developed to identify the length (normal to uniaxial stress) and width (parallel to the stress) of each γ´ phase. Two interesting findings of this investigation can be summarized as: 1) During the N-type rafting of SC, the vertical matrix channel widths are gradually decreased, and the γ phases near the vertex of the cuboidal γ´ phases disappear 2) The length, width of γ´ phases both obey lognormal distributions during creep rafting, and the standard deviations change slightly for the width, but increase significantly for the length. These above findings are of significance to multi-scale probability modeling for creep deformation and fracture.

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Klochikhin, V., S. Danilov, N. Lysenko e V. Naumyk. "Development of technology for modification of heat-resistant nickel alloy ЖС3ДК-ВІ with titanium carbonitride ultrafine powders". Innovative Materials and Technologies in Metallurgy and Mechanical Engineering, n. 2 (18 marzo 2021): 37–44. http://dx.doi.org/10.15588/1607-6885-2020-2-5.

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Purpose. To study the effect of modification by the titanium carbonitride Ti(C, N) ultrafine particles additives in the form of powder and briquettes on the structure and physical-mechanical properties of the ЖС3ДК-ВІ alloy used for the manufacture of aircraft engine turbines cast rotor blades. Research methods. Preliminary high-temperature treatment of the melt was carried out on a VIP-10 installation. On the UPPF-3M installation with the alkaline melting pot, the ЖС3ДК-ВІ alloy was modified with ultrafine particles of titanium carbonitride Ti(C,N) in an amount of 60...80 g in the form of briquettes or powder wrapped in nickel foil. The samples were subjected to homogenization at a temperature of 1210 °C with a holding time of 3.5 hours and air cooling. The chemical composition of investigated alloys was determined. The macrostructure was studied on plates ~ 4 mm thick after chemical etching. The microstructure was evaluated on microsections before and after etching in the Marble reagent. Microhardness, ultimate strength, elongation and contraction, impact strength were determined at room temperature. Long-term strength tests were carried out at 850 °C under a load of 350 MPa. The bending test of the blades was carried out on a manual screw press in accordance with GOST 14019-80. Results. The microstructure of Ti+TiCN briquettes has been studied by optical and electron microscopy. X-ray microanalysis of specimen fractures confirmed a fairly uniform distribution of titanium carbonitride in the volume of briquettes. The chemical composition, macro- and microstructure of the experimental alloy have been studied. A fracto-graphic study of the samples fracture structure was carried out. The modifying effect of titanium carbonitride ultrafine particles on the dendritic structure, distribution and change in the morphology of primary carbides, the number and distribution of carbonitride particles has been established. A comparative analysis of the mechanical and heat-resistant properties of the ЖС3ДК-ВІ alloy of standard composition and modified with ultradispersed Ti(C,N) particles has been carried out. Bending tests of turbine rotor blades were carried out. Scientific novelty. It is shown that the use of ultrafine titanium carbonitride powders for bulk modification of the heat-resistant nickel alloy ЖС3ДК-ВІ makes it possible to increase the mechanical and heat-resistant properties of the material. Increasing the amount of modifier promotes grain refinement. More stable properties and favorable structure are provided by melt modification with ultrafine Ti(C,N) particles in the form of briquettes. It was found that modification with powdered Ti(C,N) leads to a decrease in the impact toughness values due to the formation of boundary microporosity. Practical value. The technology of the heat-resistant nickel alloy ЖС3ДК-ВІ, used for the manufacture of cast rotor blades of gas turbine engines, modification with additives of titanium carbonitride Ti(C,N) ultrafine particles, providing an increased level of performance properties of finished products, has been developed.

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Dejima, Kazuhito, Osamu Nakabeppu, Yuto Nakamura, Tomohiro Tsuchiya e Keisuke Nagasaka. "Three-point MEMS heat flux sensor for turbulent heat transfer measurement in internal combustion engines". International Journal of Engine Research 20, n. 7 (18 aprile 2018): 696–705. http://dx.doi.org/10.1177/1468087418770308.

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Abstract (sommario):

A heat flux sensor was developed with micro-electro-mechanical systems (MEMS) technologies for investigating turbulent heat transfer characteristics in engines. The sensor has three thin-film resistance temperature detectors (RTDs) of a square 315 µm on a side on a 900 µm diameter circle in rotational symmetry. The performances of the MEMS systems sensor were tested in an open combustion chamber and a laboratory engine. In the open chamber tests, it was revealed that the MEMS sensor can measure the wall heat fluxes reflecting flow states of gas phase. In addition, the noise was evaluated as 3.8 kW/m2 with the standard deviation against the wall heat flux of a few hundred kW/m2. From these results, it was proved that the MEMS sensor has the potential to observe turbulent heat transfer on the order over 10 kW/m2 in the engine. In the laboratory engine test, the wall heat flux for continuous 200 cycles was measured with a good signal-to-noise ratio. The noise was evaluated as 13.4 kW/m2 with the standard deviation despite the noisy environment. Furthermore, it was proved that the MEMS sensor has the comparable scale with the turbulence in the engine because the three adjacent detectors measured similar but different phase oscillations in the local instantaneous heat fluxes. In addition, a heat flux vector reflecting the state of the local instantaneous heat transfer was visualized by the adjacent three-point measurement. It is expected that the three-point MEMS sensor will be a useful tool for the engine heat transfer research.

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45

Winterbone, D. E. "Engines versus electrons: The future of power production". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 214, n. 1 (1 febbraio 2000): 1–11. http://dx.doi.org/10.1243/0957650001537804.

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Abstract (sommario):

The demands for energy are increasing as countries become richer, and if all mankind achieved the per capita energy consumption of the United States then the total energy consumption of the world would rise by a factor of about 4.5. This would make a large demand on fuel supplies and probably increase pollution beyond a sustainable level. This paper examines the limits to the theoretical efficiency of power generation, including both heat engines and fuel cells, and demonstrates that thermal efficiencies of above 60 per cent are achievable in each case if combined plants are used. It is shown that the fuel cell has benefits over the heat engine when the plant operates for a significant time at low load.

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46

Muttahar, Moch Iqbal Zaelana, Shinta Virdhian, Purbaja Adi Putra, Dagus Resmana Djuanda, Eva Afrilinda e Amsal Genesar. "Mechanical Properties Enhancement of Al-Si-Cu-Fe Alloy Through Aging Treatment Variations". Metalurgi 35, n. 3 (28 dicembre 2020): 105. http://dx.doi.org/10.14203/metalurgi.v35i3.571.

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Al-Si alloys are being widely used as main engine components replacing iron in several parts in the automotive industry. Some of its mechanical properties were a reference in its alloy utilization. In this research, the heat treatment carried out on the specimen included solid solution treatment and the artificial aging process for aluminium alloys. Test pieces were heated on the furnace with a solid solution treatment process at 540 ° C with holding time around 5 hours and quenched at 60 °C with water quenchant, followed by 3 different aging treatment which included single-stage aging, artificial aging with pre-aged, and double stage aging. Tests carried out by hardness test, tensile strength test, impact test, metallographic and Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) observations. The results of this research showed the differences in phase constituent and morphology microconstituents due to variations of aging. The difference of each treatment could be seen in the morphology of the precipitate that is dispersed, rounded and needle-like shaped, this phase can influence the mechanical properties of Al-Si-Cu alloys. The results of mechanical testing show the highest hardness was obtained by double stage aging treatment 161.27 HRB. The highest tensile strength occurs in specimens with a single-stage aging treatment of 202.56 MPa. The highest impact resistance occurred in samples with the pre-aging treatment of 18.6 J.

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Cardoso, Marlon José, Milton Luiz Polli e Giuseppe Pintaude. "Wear analysis of PVD-coated twist drills under MQL". Industrial Lubrication and Tribology 70, n. 9 (19 novembre 2018): 1664–69. http://dx.doi.org/10.1108/ilt-10-2016-0243.

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Abstract (sommario):

Purpose Deep drilling of hardened steels is a difficult machining operation because of the high wear level of tools. This paper aims to present the main wear mechanisms observed in physical vapor deposition (PVD)-coated twist drills during deep drilling of SAE4144M steel under minimum quantity lubrication, assessed in the production of injection holders. Design/methodology/approach Two PVD coatings were tested: TiAlN and AlCrN, industrially processed, the last one being a multilayer coating. The workpiece was heat treated for a hardness of 39 HRC to be applied in a diesel engine component. The tests were performed in an industrial environment for a fixed number of holes. Two levels of cutting speed and feed rate were selected for the experiments. In addition, minimum quantity of lubrication (MQL) was compared with conventional lubrication. Scanning electron microscope was used to reveal the wear mechanisms. Findings Spalling of PVD-coating was revealed for conventional lubrication, while adhesion was observed in MQL conditions. The use of multilayered AlCrN-based coating promoted a significant reduction of adhered material on the twist drill, which is the reason for this selection in industrial operation. Practical implications Results showed that the MQL regime can be applied for this industrial application. Originality/value A detailed description of wear mechanisms, which allows a suitable selection of coating and machining variables was found for a very difficult operation, using a more economic process in terms of lubrication.

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Diazdelacruz, Jose, e Miguel Martin-Delgado. "Quantum Information Remote Carnot Engines and Voltage Transformers". Entropy 21, n. 2 (30 gennaio 2019): 127. http://dx.doi.org/10.3390/e21020127.

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Abstract (sommario):

A physical system out of thermal equilibrium is a resource for obtaining useful work when a heat bath at some temperature is available. Information Heat Engines are the devices which generalize the Szilard cylinders and make use of the celebrated Maxwell demons to this end. In this paper, we consider a thermo-chemical reservoir of electrons which can be exchanged for entropy and work. Qubits are used as messengers between electron reservoirs to implement long-range voltage transformers with neither electrical nor magnetic interactions between the primary and secondary circuits. When they are at different temperatures, the transformers work according to Carnot cycles. A generalization is carried out to consider an electrical network where quantum techniques can furnish additional security.

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Морозова, Ирина Владимировна, e Юрий Матвеевич Терещенко. "Удосконалення процесу сумішоутворення в камерах згоряння теплових двигунів". Aerospace technic and technology, n. 4sup2 (27 agosto 2021): 29–34. http://dx.doi.org/10.32620/aktt.2021.4sup2.04.

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Abstract (sommario):

Improving the mixture formation and combustion of various types of fuels in the combustion chamber is one the ways for the development of modern engines. Requirements for reliability, durability, tactical and technical characteristics and, importantly, for environmental friendliness pose new problems in this area of science and technology. This is largely determined by the degree of perfection individual processes in the engine operating cycle. An increase in power in accordance with the requirements for an increase in energy saturation and productivity of transport vehicles is limited by the resource and reliability of the engine due to an increase in thermal and mechanical loading of the main parts. The expansion the scope of application is limited by increased emissions harmful substances with exhaust gases, levels noise and vibration a running engine. Consumption increasing amounts liquid fuels requires further improvements in fuel efficiency. The main process of the working cycle a piston engine is the process fuel combustion. Fuel efficiency, power, service life and environmental performance depend on its quality. Therefore, the greatest attention is paid to the improvement of this process. The development of modern engines consists in the study and improvement of the working process on liquid and gaseous fuel components. Based on the foregoing and in accordance with the urgency of this problem, the method of electromagnetic action on fuel was studied. The results of experimental studies have shown the effectiveness the use of electro physical effects on hydrocarbon fuel to improve the parameters and characteristics of heat engines. It has been established that the electro physical effect on hydrocarbon fuel increases the completeness of fuel combustion by 4 ... 6% and reduces the deposition of carbon deposits in the combustion chamber of a gas turbine engine by 20 ... 25%. Improvement the fuel combustion processes in the previous phases leads to a reduction in the afterburning phase, which entails a decrease in the exhaust gas temperature, a decrease in the concentration of carbon monoxide by 0.64 ... 0.7%, the concentration of hydrocarbons by 25 ... 35% and the concentration of nitrogen oxide by 12 ... 16%.

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Mishra, Nibedita, Pranab K. Mohapatra e Mukesh K. Raval. "In Silico Design of a Single Protein Molecular Photoreaction Center". Micro and Nanosystems 12, n. 2 (19 agosto 2020): 112–21. http://dx.doi.org/10.2174/1876402911666190719111104.

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Abstract (sommario):

Background: Research on harvesting solar energy through an artificial photosynthetic device is gaining momentum in the present era. The device is a promising solution to the energy crisis by overcoming the crunch in fossil fuel and low efficiency of heat engine. Reports are available on design of isolated parts of the photosynthetic device, for example, only sensitizer or only redox unit containing metallo-peptides. Objective: An attempt has been made to design an in silico photoreaction center in a single chain protein matrix containing all the three basic units: sensitizer, electron donor, and acceptor mimicking the photosynthetic reaction center II. Methods: A single chain of a protein containing a closely packed transmembrane four-helix bundle (PDB ID 2bl2 A) is selected for the purpose. The protein is suitably mutated in silico to accommodate the basic elements of a reaction center: Mn-Ca binding site as water oxidizing moiety, Fe-binding site as quinine reducing moiety, and MgDPP as photosensitizer to achieve the desired function of photoredox reaction. Results: A photoelectron transport protein has been designed, which may incorporate into the bilayer membrane system. It has the potential to photo-oxidize water to oxygen on one side and reduce quinone on the other side of the membrane. The stability and transmembrane orientation of the molecular device in an artificial membrane system has been validated theoretically by molecular dynamics study. Conclusion: An attempt to incorporate in silico all the elements essential for a photoelectron transport device into a single chain transmembrane protein model is the first of its kind. Donor and acceptor moieties are separated on the inner and outer side of a membrane bilayer. These features make the model unique and novel. The design of the model is the first step towards the study of experimental viability of the model, which remains to be validated in future.

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