Insights on the Formation Mechanism of Ultra-Low Friction of Phenolic Resin Graphite at High Temperature

In the present paper, the influences of high temperature on the tribological properties of phenolic resin graphite (PRG) sliding against tungsten carbide-nickel (WC-Ni) alloy in ambient air were investigated systematically. Results demonstrated that the antifriction behaviors of PRG was sensitive to high temperature and PRG exhibits ultra-low coefficient of friction (CoF) of about 0.01–0.015. The low CoF is attributed to the formation of graphite tribofilms, which shows different formation processes on the contact interface at different temperatures (room temperature, 200, 300 and 400 °C). These findings provide insight into the formation mechanism of graphite tribofilms, and provide an important basis for improving the tribological properties of graphite-based friction materials and manufacturing new graphite for seal applications.

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

Materials ◽

10.3390/ma12122011 ◽

2019 ◽

Vol 12 (12) ◽

pp. 2011 ◽

Cited By ~ 1

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.

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

JSME 2020 Conference on Leading Edge Manufacturing/Materials and Processing ◽

10.1115/lemp2020-8522 ◽

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.

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

Coatings ◽

10.3390/coatings9070450 ◽

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.

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

REVIEWS ON ADVANCED MATERIALS SCIENCE ◽

10.1515/rams-2021-0028 ◽

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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Self-Lubricating Behavior of ZrO2(Y2O3)-Mo-CaF2-Graphite Composite

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.815.584 ◽

2013 ◽

Vol 815 ◽

pp. 584-587 ◽

Cited By ~ 2

Author(s):

Ling Qian Kong ◽

Qin Ling Bi ◽

Sheng Yu Zhu ◽

Wei Min Liu

Keyword(s):

High Temperature ◽

Low Temperature ◽

High Temperatures ◽

Tribological Properties ◽

Hot Pressing ◽

Tribological Behavior ◽

Low Friction ◽

Friction Coefficients ◽

Graphite Composite ◽

Worn Surface

t is of great importance to find ways to lubricate ZrO2ceramic. In this paper, a kind of ZrO2 matrix high temperature self-lubricating compositewith addition of CaF2 and graphite as lubricants was prepared by hot-pressing. It was found that the tribological properties of ZrO2(Y2O3)-CaF2-graphiteshow a good tribological behavior both at low temperature and high temperatures. The low friction coefficients of ZrO2 (Y2O3)-Mo-CaF2-graphite at high temperatures were due to the perfect lubricity of CaMoO4 which was formed on the worn surface at high temperatures.

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Study on Phase Stability during Pressure-Less Sintering Process of Slag α-Sialon Powder and Properties of As-Sintered Materials

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.746.97 ◽

2013 ◽

Vol 746 ◽

pp. 97-100 ◽

Cited By ~ 1

Author(s):

He Zhang ◽

Yao Deng ◽

Ying Zhang ◽

Jiu Xin Jiang

Keyword(s):

High Temperature ◽

Formation Mechanism ◽

Phase Stability ◽

Sintering Process ◽

Temperature Synthesis ◽

High Temperature Synthesis ◽

Unit Cells ◽

Different Temperatures ◽

Sialon Powder ◽

Sintered Materials

The pressure-less sintering of slag α-Sialon powder, derived from slag wastes by self-propagating high-temperature synthesis technology, was carried out and the phase assemblages of slag α-Sialon sintered at different temperatures were studied. The results showed that the formation of β-Sialon phase did occur during the pressure-less sintering and was restrained to some extent via mass diffusion of Ca2+/Mg2+ added in embedded powder in samples. α-Sialon phase with two different unit cells was detected in samples sintered at 1700°C and above, and the formation mechanism was also discussed.

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High-Temperature Tribological Properties of ReB2-Based Ceramic/Si3N4 Sliding Pairs

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1016.978 ◽

2021 ◽

Vol 1016 ◽

pp. 978-983

Author(s):

Takashi Murakami ◽

Tsuguyori Ohana

Keyword(s):

High Temperature ◽

Tribological Properties ◽

Low Friction ◽

Friction Coefficients

Our group prepared an ReB2-based ceramic with a composition of Re-74.5at% B to investigate its microstructure, high-temperature microvickers hardness, and high-temperature tribological properties in air. The microvickers hardness of the ReB2-based ceramic was higher than 2600 at temperatures below 1073 K. The friction coefficients of ReB2-based ceramic/Si3N4 sliding pairs were stable and low (≃ 0.15) at 1073 K. We concluded that the low friction coefficients of the sliding pairs resulted from the formation of low-friction hexagonal BN and B2O3 films. The friction coefficients of the ReB2-based ceramic/Si3N4 sliding pairs were also low at 298 K (≃ 0.3 to 0.4) and 1273 K (≃ 0.1), but were unstable and high ( 0.6) at 673 K.

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GERMINATION AND VIGOUR IN SEEDS OF THE COWPEA IN RESPONSE TO SALT AND HEAT STRESS

Revista Caatinga ◽

10.1590/1983-21252019v32n115rc ◽

2019 ◽

Vol 32 (1) ◽

pp. 143-151 ◽

Cited By ~ 1

Author(s):

Luma Rayane de Lima Nunes ◽

Paloma Rayane Pinheiro ◽

Charles Lobo Pinheiro ◽

Kelly Andressa Peres Lima ◽

Alek Sandro Dutra

Keyword(s):

Salt Stress ◽

Heat Stress ◽

High Temperature ◽

Low Temperature ◽

Vigna Unguiculata ◽

Salt Concentration ◽

Dry Weight ◽

Germination Percentage ◽

Different Types ◽

Different Temperatures

ABSTRACT Salinity is prejudicial to plant development, causing different types of damage to species, or even between genotypes of the same species, with the effects being aggravated when combined with other types of stress, such as heat stress. The aim of this study was to evaluate the tolerance of cowpea genotypes (Vigna unguiculata L. Walp.) to salt stress at different temperatures. Seeds of the Pujante, Epace 10 and Marataoã genotypes were placed on paper rolls (Germitest®) moistened with different salt concentrations of 0.0 (control), 1.5, 3.0, 4.5 and 6.0 dS m-1, and placed in a germination chamber (BOD) at temperatures of 20, 25, 30 and 35°C. The experiment was conducted in a completely randomised design, in a 3 × 4 × 5 scheme of subdivided plots, with four replications per treatment. The variables under analysis were germination percentage, first germination count, shoot and root length, and total seedling dry weight. At temperatures of 30 and 35°C, increases in the salt concentration were more damaging to germination in the Epace 10 and Pujante genotypes, while for the Marataoã genotype, damage occurred at the temperature of 20°C. At 25°C, germination and vigour in the genotypes were higher, with the Pujante genotype proving to be more tolerant to salt stress, whereas Epace 10 and Marataoã were more tolerant to high temperatures. Germination in the cowpea genotypes was more sensitive to salt stress when subjected to heat stress caused by the low temperature of 20°C or high temperature of 35°C.

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