Papers by Keyword: Friction and Wear

Abstract: Based on MMW-1A vertical multifunctional friction and wear tester for the study,taking steel 45 as the research object, randomly changing the experiment load, speed, sliding distance and the size of the contact area, then the data we collect are processed and analyzed by principal component analysis, and obtained linear regression models by principal component regression, regression model has been tested with good fitting effect. The results showed that the principal component analysis method is also suitable for experimental study of friction and wear, explore new methods in the analysis of tribology. It shows that load, speed and sliding distance have a weakening effect on the friction coefficient, on the contrary, the contact area has a promoting role to the friction coefficient.

Abstract: The systems of DLC film/304 stainless steel were separately treated with cryogenic treatment,annealing treatment and composite treatment of cryogenic+annealing to study the effects of different treatments on friction and wear property of DLC film/304 stainless steel,mainly from the film’s hardness,fracture toughness and surface roughness. The results show that the friction and wear property of DLC film/304 stainless steel is improved in different degrees by the three kinds of treatment,single cryogenic treatment performs best. It is because that three kinds of treatment all can improve the fracture toughness of DLC film and reduce DLC film’s surface roughness,but only single cryogenic treatment doesn’t reduce film’s hardness and makes film get the best lubricity and highest hardness-to-elasticity ratio. The residual stress of film/substrate composite system can be effectively adjusted by cryogenic or annealing,but annealing often sacrifices DLC film’s hardness as the price.

Abstract: The objective of this research is to study wear behaviors of TiN, nanolaminated AlCrN and nanocomposite TiAlSiN coated on cemented carbide end mill deposited by cathodic arc physical vapor deposition methods in comparison with uncoated end mill. Wear behaviors were investigated by nanoindentation hardness test, scratch test and cutting test. Oxidation test was also done in air at temperatures of 700°- 900°C in order to evaluate resistance of oxidation. In the nanoindentation hardness and scratch tests, nanocomposite TiAlSiN coating exhibited higher hardness than TiN and nanolaminated AlCrN coatings. The nanolaminated AlCrN coating represented the highest adhesion ability in terms of critical load and the lowest coefficient of friction in comparison with the TiAlSiN and TiN coatings, respectively. The cutting performance, represented in terms of maximum flank wear as a function of cutting length, was found to be highest in the AlCrN coating. Oxides of these coatings, i.e., TiO₂ for TiN, TiO₂ for TiAlSiN and Cr₂O₃ for AlCrN, generated at different temperatures of 700°, 800° and 900°C, respectively. From all of results, it is obvious that the AlCrN coating exhibited more excellent wear resistance and oxidation resistance than the uncoated end mill, TiN coating and TiAlSiN coating.

Abstract: In this paper, the friction and wear behavior of FKM, NBR and FKM/NBR blends with the same Shore hardness was investigated in the MPV - 600 wear tester under water lubrication based on the actual working parameters of the screw pump. Wear mechanism of FKM/NBR blends with different load was also analyzed according to their wear loss and frictional coefficient. The results showed that the wear resistance of NBR was improved by the addition FKM. FKM/NBR blend with ratio of 2:8 owned the optimal wear resistance, which was close to that of FKM. The wear of FKM and FKM/NBR blend with ratio of 2:8 was controlled by fatigue wear, and the others were mainly controlled by abrasive wear.

Abstract: Cu-La₂O₃ composite was fabricated by internal oxidation method using powder metallurgy. Its sliding behavior was studied under various electrical currents and applied loads. The worn surfaces of Cu-La₂O₃ composite were characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) to probe the wear mechanisms. The results indicated that applied load has a significant effect on the wear rate of the Cu-La₂O₃ composite pins. The wear rate displayed the minimum value at the load of 50N during electrical sliding processes.

Abstract: As a new type of gear transmission, the gear transmission with meshed medium belt has advantages of reducing vibration noise and friction damage on the gear surface. During the process of the gear transmission with meshed medium belt, the friction and wear is mainly occurred on the medium belt, so the service life of the medium belt has a direct effect on the performance and efficiency of the transmission system. The friction and wear mechanism of the medium belt is researched and effective ways to prolong the service life of the medium belt are given in this paper.

Abstract: The friction and wear properties of the overbased calcium sulfonate complex grease and polyurea grease were evaluated using an Optimol SRV reciprocating friction and wear tester under the boundary lubrication conditions. The morphologies of the worn surfaces of the AISI 52100 steel discs were observed using a scanning electron microscope (SEM). In addition, the elemental compositions and chemical states of several typical elements on the worn surfaces of the AISI 52100 steel discs were examined by means of X-ray photoelectron spectroscopy (XPS). The results show that the overbased calcium sulfonate complex greases and polyurea grease have stable friction coefficients as low as 0.10-0.11. The calcium sulfonate complex grease has better wear resistance properties than polyurea grease, polyurea grease has better reducing friction properties than calcium sulfonate complex grease, According to the XPS analyses, it is considered that the formation of tribochemical films led to lower friction coefficient and high wear resistance.

Abstract: Bamboo fiber reinforced resin matrix brake materials were selected as research object, dry and wet friction experiment was conducted on MM200 abrasion tester. Results show that: friction coefficient drops down to a very low level under wet condition, wear rate of samples and counterparts also decreases, but the values of friction coefficient are still in the range of dry friction. Under dry and wet conditions, the tribilogical performance of sample has different relationships with the pressure and speed, especially with the speed. Friction surface was lubricated and cooled by water, in the meantime, the formation of friction film is suppressed, which leads to the differences of the tribilogy performance between dry and wet conditions. Morphologies of fricion surface was observed by SEM, worn surface in wet braking was not covered by friction film, many fine cracks and some patches were scattered over the substrate.

Abstract: The Carbon nano-tubes (CNTs) reinforced Cu-based (CNTs/Cu) composites were obtained by powder metallurgy processes. The effects of CNTs content on the microstructure, density and hardness of the Cu-based composites were investigated. The tribological properties of the composites were studied by using a ball/disk friction tester. The results indicate that the density values of the composites gradually decrease with the increment of CNTs content, while for the hardness values, firstly increase and then decrease; and the maximal hardness values was obtained when the composite contains 0.75% CNTs. The CNTs content exerts a great effect on the friction coefficient of the composite. It has been found that the anti-wear property of the CNTs/Cu composites is excellent, at the same time, the hardness and density values are also in the reasonable ranges when the CNTs content is relatively low. The concerning mechanism has been analyzed in the present paper.

Abstract: The ceramic coatings, on the substrate of LY12 Al alloy, were prepared by micro-arc oxidation (MAO) technique with different electrical source parameters. The microstructure and tribological properties of the resulting micro-arc oxidation ceramic coatings(MAOC) were tested and analyzed by Nano-scratch tester, Micro-hardness tester and ball-on-disk friction tester etc. The results indicate that the thickness, roughness, micropore sizes and wear-resistance of MAOC increase with impulse frequency decreasing, however, the porosity is correspondingly reduced.