Papers by Keyword: Tribological Property

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Authors: Hyun Hwi Lee, Seung Ho Kim, Bhupendra Joshi, Soo Wohn Lee
Abstract: Oxide ceramics such as alumina and zirconia are industrially utilized as cutting tools, a variety of bearings, biomaterials, and thermal and corrosion-resistant coatings due to their high hardness, chemical inertness, high melting point, and ability to retain mechanical strength at elevated temperatures. In this research, the effect of other ceramic additives (TiO2) and h-BN within alumina(α-Al2O3) and yttria-stabilized tetragonal (Y-TZP) composite was studied with respect to the mechanical and tribological properties. The lowest coefficient of frction of 0.45 was observed for the ZTA ceramic composite with hBN-TiO2. The highest hardness, fracture toughness and flexural strength were obtained as 15.7GPa, 5.2MPam-1/2, 712MPa, respectively.
Authors: Yan Zang, Chun Hua Hu, Yu Lin Qiao
Abstract: The trbriological properties of FeS solid lubrication composite layer were carried out on the type MS-T4000 friction wear testing machine. Morphology and elements analysis of wear surfaces was carried out on ultra high resolution field emission scanning electron microscope (FESEM) and X-ray photoelectron spectroscopy (XPS). It is shown that the friction process of FeS solid lubrication composite layer can be divided into three stages. The friction coefficient of FeS solid lubrication composite layer is about 0.16 in the first stage, the friction mainly occurred in the surface of FeS solid lubrication. The friction coefficient is about 0.20 to 0.25 and is about 0.40, in the second stage and the third stage, respectively. The wear surface of FeS solid lubrication composite layer was smooth without obvious furrow. On the wear surface, there were mainly granular and flatteners-like FeS films.
Authors: Shi Yu Ma, Shao Hua Zheng, Hai Yang Ding, Wei Li
Abstract: In this paper, the author does research on the surface modified of nanometer ZrO2/SiO2 composite and makes it a good dispersivity in organic solvents. As lubricating oil additive, added it into the base oil with different concentration. Anti-wear and reducing friction performances measured by the four ball test and the thrust-ring tribotester. The results showed that the average friction coefficient decreased 21.14%, the weight lost of the thrust-ring was no wear or negative wear when the additive concentration was 1wt%. The worn surfaces were quite different compared without additive, the grooves formed during the friction experiment become smooth and finally a narrow wear scar. There were many white particles and dimples on gray surface, the white particles were higher than those of gray parts. The white particles was ZrO2/SiO2 composites according to EDS and XRD analysis. The Si and Zr elements appeared on the worn surfaces can not be cleaned out in petroleum ether and ultrasonic ambiance, this is a dynamic self-healing mechanism .
Authors: Xiao Lan Hu, Zhong Lin, Mou Fa Yu
Abstract: Tribological behaviors and wear mechanism of bismaleimide resin and its composites modified by potassium titanate whiskers were investigated. The composites with outstanding tribological properties were prepared through several coupling agents and whisker contents under different friction loads. The incorporation of whiskers treated with silane into the matrix effectively improved wear properties and friction stability of the matrix, especially at severe friction condition as 30 kg. The wear volume of the neat resin at 15 kg and 30 kg friction load are 1.14 and 6.87 mm3, respectively. However, the wear volume of the composites containing 3 wt% potassium titanate whiskers at 15 kg and 30 kg friction load are 0.75 and 1.14 mm3, respectively. Furthermore, the addition of whiskers increased the ability to resist plastic deformation and crack of the matrix in a higher friction load.
Authors: You Qiang Wang, Li Jing Zhang
Abstract: Thordon is a new liner material used widely in water-lubricated bearings in virtue of its shockproof characteristic, high load and wear resistance. The category of materials used in water-lubricated bearings was briefly outlined and tribological characteristics of most of the materials were compared in the paper. The defects of the traditional water-lubricated bearing materials were listed and the advantage of the Thordon bearing was presented. The development status and the tribological characteristics of the water-lubricated Thordon bearings were studied. The application prospects of the water-lubricated Thordon bearings were introduced in the end of the paper.
Authors: Sheng Dai, Dun Wen Zuo, Xian Rui Zhao, Jin Fang Wang
Abstract: To improve the surface hardness and wear resistance of metal parts. Ni-based chromic carbide composite coating was prepared on the carbon steel (0.45 mass% C) substrates by laser cladding. Microstructure and wear properties of composite coatings were investigated by SEM, EDS, XRD, Vickers micro-hardness tester and wear machine. The results show that good metallurgical bonding between the Ni-based chromic carbide composite coating and carbon steel substrate. Micro-hardness of Ni-based Cr3C2 composite coating along the layer depth presents an evident stepladder distribution. The average micro-hardness of the laser clad coating is about 950 HV. The result of wear experiment shows that Ni-based Cr3C2 composite coating processes good wear resistance.
Authors: Y.Q. Wang, Ming Yi Zheng, Kun Wu
Abstract: The wear and corrosion protective coatings were synthesized on AZ91 Mg alloy and Mg matrix SiCw/AZ91 composite by a microarc oxidation (MAO) technique in an alkali-silicate electrolyte solution. The phase structure of the coatings was analyzed using X-ray diffraction (XRD). The tribological properties of the coatings sliding against GCr15 steel were investigated on a pin-on-disc friction and wear tester. The morphology and elemental composition of the worn coating surface were determined by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The potentiodynamic polarizing curves were measured to evaluate the corrosion resistance of the coatings. The results showed that the application of the coatings changed evolution tendency of friction coefficients and wear mechanism. For coated Mg alloy and Mg matrix composite, both the wear resistance and corrosion resistance were improved greatly.
Authors: Hua Tang, Wen Jing Li, Chang Sheng Li
Abstract: The YBa2Cu3Ox/Ag and Bi2Sr2CaCu2Ox/Ag self-lubricating composites were prepared using powder metallurgic method. The crystal structure and morphology of the as-synthesized samples were characterized by XRD and SEM. The YBa2Cu3Ox/Ag and Bi2Sr2CaCu2Ox/Ag self-lubricating composites were found to compose of superconductor phase and Ag phase. The tribological properties from ultra-low temperature to room temperature of the composites were studied by pin-on-disk friction test. It was found that the friction coefficients of pure YBa2Cu3Ox (YBCO) and Bi2Sr2CaCu2Ox (BSCCO) were both dropped abruptly when the temperature cooled below the superconducting transition temperature. At room temperature, the friction coefficient of pure YBa2Cu3Ox is 0.68~0.95, when mixing 15wt% Ag, the friction coefficient of the sample decreased to the lowest value 0.11. The friction coefficient of pure Bi2Sr2CaCu2Ox is 0.15~0.17, When Ag content reach 10wt%, the coefficient was lowest (average value is 0.13). The addition of appropriate amount of Ag obviously improve the tribological property of YBCO, while only slightly meliorate that of BSCO. On the other hand, the YBCO/Ag composites exhibit better tribological properties than BSCCO/Ag composites at higher load under the same experimental condition.
Authors: Hong Xing Xu, Xin Hua Yuan, En Bo Zhu, Shuang Lian Li, Ling Chen, Zhi Rui Han
Abstract: The polytetrafluoroethylene (PTFE) matrix composites which filled with polyphenylene sulfide (PPS) fiber, poly-p-phenelenferephthalamide (PPTA) fibre or glass fiber (GF)) and graphite at various mass fractions were prepared by the processes of mechanical blending, compression molding and sintering. The mechanical properties of the composites, such as tensile strength, impact strength and hardness were investigated. The results show that tensile strength and elongation at break markedly decrease but elasticity increases by filling with fibers. Impact strength decreases by filling with PPS and GF, and the composite displays brittle characteristic. However, the impact strength rapidly increases by filling with PPTA fiber. Hardness increases with the fibers content increases, and decreases with graphite content increases. Filling graphite into PTFE has light effect on the impact and tensile strength of composites. The tribological properties of the composites were investigated on M-2000 wear tester at dry friction condition. The wear mechanism was also discussed and the wear surfaces were examined by SEM. The result indicates that fibers which diffused in PTFE matrix wind with PTFE molecule chain, and then form grid structure. The load-bearing capacity of composites can be obviously enhanced and the trend of block fragmentations slide is inhibited, so that the tribological properties are improved markedly.
Authors: Xin Chun Chen, Zhi Jian Peng, Zhi Qiang Fu, Cheng Biao Wang
Abstract: A series of graded films of Cr/CrN/ CrNC/CrC/(Cr-DLC)/[(Cr-(Cr-DLC))×10] were deposited on Si(100) wafer and 4135 alloy structural steel using cathodic vacuum arc technique and direct current magnetron sputtering method combined with ion beam sputtering. The surface morphology, microstructure, nano-hardness, adhesion and wear properties of the films were investigated using 3-dimensional white-light interfering surface profiler, scanning electron microscopy, nanoindentation, scratch adhesion test, ball-on-disc test, etc. It was measured that the as-prepared Cr-doped DLC multilayered thin films have a strong adhesion to the substrates with a critical load exceeding 80 N, and the average friction coefficient during 30 min test in air was 0.23. This film will be promising in application against wear.
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