scholarly journals High Temperature Anti-Friction Behaviors of a-Si:H Films and Counterface Material Selection

Coatings ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 450
Author(s):  
Qunfeng Zeng ◽  
Liguo Qin
Keyword(s):  
High Temperature ◽  
Tribological Properties ◽  
Material Selection ◽  
Friction Pair ◽  
Ceramic Materials ◽  
Low Friction ◽  
Friction Mechanism ◽  
Temperature Oxidation ◽  
Friction Process ◽  
Hydrogenated Amorphous

In the present paper, the influence of self-mated friction materials on the tribological properties of hydrogenated amorphous silicon films (a-Si:H films) is studied systemically at high temperature. The results are obtained by comparing the tribological properties of a-Si:H films under different friction pair materials and temperatures. The a-Si:H films exhibit super-low friction of 0.07 at a temperature of 600 °C, and ceramic materials are appropriate for anti-friction behaviors of a-Si:H films at high temperature. The results of tribotests and observations of the fundamental friction mechanism show that super-low friction of a-Si:H films and ceramic materials of the friction system are involved in high temperature oxidation; this also applies to the tribochemical reactions of a-Si:H films, steel and iron silicate in open air at elevated temperature in the friction process.

Low-friction mechanism of silicon carbide and cemented carbide in water

2020 ◽  
pp. 135065012092868
Author(s):  
Fei Guo ◽  
Fan Wu ◽  
Fangyong Wu ◽  
Yuming Wang
Keyword(s):  
Silicon Carbide ◽  
Tribological Properties ◽  
Rotation Speed ◽  
Hydrodynamic Lubrication ◽  
Cemented Carbide ◽  
Matched Pairs ◽  
Low Friction ◽  
Friction Mechanism ◽  
Friction Coefficients ◽  
Test Conditions

The tribological properties of self-mated silicon carbide, self-mated cemented carbide, and cemented carbide/silicon carbide under water lubrication were studied. The three matched pairs could achieve low-friction coefficients (0.01–0.03) under certain test conditions. Additionally, the dependence of the friction coefficients on the rotation speed and load were measured. By combining these results with the observed surface topography and wear measurements, it was determined that the three matched pairs were in the hydrodynamic lubrication. In addition, combined with experiments in ethylene glycol and PAO40, it was shown that the actual viscosity of the lubricant had a significant influence on the realization of low friction. Furthermore, matching materials had an influence on the tribological properties, which may be related to the surface wettability of the lubricant.

Corrosion Issues of HTR Structural Metallic Materials

2008 ◽  
Author(s):  
Celine Cabet ◽  
Brigitte Duprey ◽  
Gouenou Girardin ◽  
Annie Page`s ◽  
Martine Blat
Keyword(s):  
High Temperature ◽  
Corrosion Behavior ◽  
Gas Flow ◽  
Material Selection ◽  
Specimen Preparation ◽  
Residual Water ◽  
Metallic Materials ◽  
Preparation Temperature ◽  
Benchmark Test ◽  
Temperature Oxidation

Within the framework of the ANTARES program, AREVA NP, EDF and the CEA have launched a joint R&D program on metallic materials for VHTR. Reference alloys for circuit and Intermediate Heat eXchanger (IHX) are nickel-based with about 22%wt. of chromium. Compatibility with the HTR primary helium appears to be a determining property for the material selection and qualification. The coolant is actually polluted by a low level of impurities that can interact with metals at high temperature. Oxidation, carburization and/or decarburization occur, in relation to atmosphere characteristics, temperature and alloy chemical composition. As these corrosion effects can notably influence the mechanical properties, they often are determining to the component service life. Since the corrosion behavior is highly sensitive to environmental conditions, material studies require dedicated facilities that shall allow for a strict control of the environment throughout the entire specimen exposure. AREVA NP, CEA, and EDF have developed experimental loops respectively under the names the Chemistry Loop, CORINTH and CORALLINE, ESTEREL; these high temperature helium flow systems are equipped with high accuracy hygrometers and gas analyzers. A benchmark was defined to cross-validate the lab devices and procedures. It is composed of two tests. The joint protocol sets the operating parameters in terms of material, specimen preparation, temperature and heating program, gas pressure and flow rate, time, gas composition. Corrosion is assessed by mass change associated to observations and analyses of the corroded coupons considering the surface scales (nature, morphology and thickness), the internal oxidation (nature, distribution and depth) and the possible carburization/decarburization (type and depth). For benchmark test 1, AREVA NP, CEA, and EDF produced similar results in terms of operation of the tests as well as about the corrosion criteria. On the other hand, benchmark test 2 showed a difference in the residual water vapor level between loops that was shown to strongly influence the specimen behavior. Discrepancies in the alloy corrosion were studied regarding gas flow rates and effective oxygen potential in helium. As a consequence, the experimental tools and procedures have been upgraded. French laboratories have now efficient corrosion facilities and methods at their disposal to study and qualify the corrosion behavior of structural materials in HTR environment.

Effect of the Surface Relief of HfB2-SiC Ceramic Materials on Their High-Temperature Oxidation

2019 ◽  
Vol 64 (13) ◽  
pp. 1681-1686 ◽  
Author(s):  
E. P. Simonenko ◽  
N. P. Simonenko ◽  
A. N. Gordeev ◽  
A. F. Kolesnikov ◽  
A. S. Lysenkov ◽  
...  
Keyword(s):  
High Temperature ◽  
Surface Relief ◽  
High Temperature Oxidation ◽  
Ceramic Materials ◽  
Temperature Oxidation ◽  
Sic Ceramic

scholarly journals Tribological Properties of Mo-Si-B Alloys Doped with La2O3 and Tested at 293–1173 K

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2011 ◽  
Author(s):  
Wenhu Li ◽  
Taotao Ai ◽  
Hongfeng Dong ◽  
Guojun Zhang
Keyword(s):  
High Temperature ◽  
Tribological Properties ◽  
Laser Scanning ◽  
Wear Behavior ◽  
Surface Oxidation ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Low Friction ◽  
Friction Coefficients ◽  
Wear Rates

According to the stoichiometric ratios of Mo-10Si-7B, Mo-12Si-8.5B, Mo-14Si-9.8B, and Mo-25Si-8.5B, some new Mo-Si-B alloys doped with 0.3 wt % lanthanum (III) oxide (La2O3) were prepared via liquid-liquid (L-L) doping, mechanical alloying (MA), and hot-pressing (HP) sintering technology. The phase-composition and microstructure were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The worn surfaces of the plate specimens were studied by confocal laser scanning microscopy (CLSM). Then, the tribological properties of Mo-Si-B alloy doped with sliding plate specimens of 0.3 wt % La2O3 were investigated against the Si3N4 ball specimens. The friction coefficients of Mo-Si-B alloys decreased and the wear rates of the alloys increased with test load. The high-temperature friction and wear behavior of Mo-Si-B alloy are related to the surface-oxidation and contact-deformation of the alloy at a high temperature. The low friction coefficients and the reduced wear rates are thought to be due to the formation of low friction MoO3 films. MoO3 changed the contact state of the friction pairs and behaved as lubricating films.

Tribological Properties Between a-C:H Coatings and SiO2 at High Temperature

2020 ◽  
Author(s):  
Noritsugu Umehara ◽  
Kota Konishi ◽  
Motoyuki Murashima ◽  
Takayuki Tokoroyama
Keyword(s):  
High Temperature ◽  
Friction Coefficient ◽  
Wear Rate ◽  
Tribological Properties ◽  
Friction And Wear ◽  
Wear Track ◽  
Severe Damage ◽  
Friction Test ◽  
Low Friction ◽  
Disk Friction

Abstract Tribological properties of a-C:H coatings has been investigated in various friction conditions. It is clear that temperature and mating materials give effects on tribological properties. In this study, we especially focus on the effect of mating material on its tribological properties of a-C:H coatings. Ball-on-disk friction test is conducted between a-C:H coating and 5 kinds of mating material, which is SiC, SiC(O)_800 (SiC oxidized at 800°C), SiC(O)_1050°C, SiC(O)_1300°C, and Quartz glass. It is found that a-C:H coatings shows low friction coefficient and low specific wear rate when O/Si ratio of the element content of mating material is 2, in other words, mating material is SiO2. In the wear scar of a-C:H coating after friction test with SiC, severe damage was confirmed. It is considered that a-C:H coating and SiO2 show low adhesion even at high temperature, which leads low friction and wear. Compared SiC(O) with Quartz, the friction coefficients with a-C:H coatings are respectively 0.013 and 0.038. Even though SiC(O) and Quartz are both SiO2, the tribological properties are different. On the wear track of SiC(O), transferred things from a-C:H coating are confirmed.

scholarly journals High-temperature tribological properties of diamond-like carbon films: A review

2021 ◽  
Vol 60 (1) ◽  
pp. 276-292
Author(s):  
Qunfeng Zeng ◽  
Zekun Ning
Keyword(s):  
High Temperature ◽  
Tribological Properties ◽  
Rapid Development ◽  
Carbon Films ◽  
Lubricating Oil ◽  
Diamond Like Carbon ◽  
Oil And Grease ◽  
Low Friction ◽  
Preparation Methods ◽  
Thermal Stability Of

Abstract The rapid development of aerospace industry has made more and more machinery parts of equipment working at high temperature. Due to the lubrication failure of lubricating oil and grease at high temperature, solid lubricant coatings are almost the only effective method to achieve super low friction at high temperature. In recent years, the tribological properties of diamond-like carbon (DLC) films have been extensively studied at high temperature. The present study reviews the microstructure of DLC films and the influence of doping different elements on the structure of DLC films. Second, the mechanical properties and thermal stability of pure DLC films and DLC doped with different elements are also described. DLC films have different microstructures and tribological properties by different preparation methods. Finally, the high-temperature lubrication failure mechanism of DLC films and the tribological properties of DLC films when doped with different elements are discussed from the macro and micro perspectives.

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