| In most circumstances, the lower friction coefficient is needed for the components surface to decrease the wear in design, however, there are some others which are used as the friction transmission or damping device require the higher friction coefficient and at the same time, the better wear resistance. But it is unfortunate that these parts either have the lower friction coefficient or its attenuation is serious, which fails to meet the demands in industry. This problem can be well settled by preparing the ceramic coating featured with the good friction coefficient on their surface.In this paper, the conventional Al2O3-13%TiO2and WC-10Co-4Cr powders were used as the feedstocks. First, the preparation of the WC coatings were optimized by choosing different critical plasma spray parameter(CPSP) using the plasma spray (APS), and then the Al2O3-13%TiO2coatings made by two kinds of powder(ATS and ATB coating) were prepared by the parameters that are already mature in industrial application. The microstructure and phases of the coatings were examined using scanning electron microscope(SEM) and X-ray diffraction(XRD); The static and dynamic anti-skidding properties were represented by the static friction coefficient tester self-made and MMS-1G high speed tribometer; The coatings tribological behavior in low-speed and high-speed were conducted by different testers and the wear mechanism of the coating were analyzed by the way. The results as follows:1. The CPSP has an great influence on WC grains thermophysical behavior in their flying. The microstructure, density and mechanical properties of the WC coating is sharply promoted by decreasing the CPSP, which is comparable to HVOF coating. And the ATS and ATB coating are typical of lamellar structure and existing defects such as pores, microcrack and so on, meanwhile, the main phase is comprised of γ-Al2O3. The microhardness and tensile strength of WC coating is better than the ATS and ATB coating but its fracture toughness is slightly lower than ATS coating. 2. The static anti-skidding property of coating is related to its material, surface roughness, interface state and friction pair. The anti-skidding property of WC coating is better than the ATS and ATB coating in the same condition. The three coatings’ anti-skidding properties are increased with the increases of surface roughness. The anti-skidding property of all coatings is obvious weakened when the oil existing on its surface but will not for water, meanwhile, it will rise noticeably when used the rubber as the friction pair in dry condition.3. In the dynamic anti-skidding property test, the results show the anti-skidding property of the three coatings are decreased with the increase of load and speed and the WC coating is characterized as the most excellent anti-skidding property in the same condition, which is resulted from the different microstructure.4. In the low-speed wear test, the friction coefficient of the three coatings is decreased with the increase of load and speed but its wear rate is just opposite; At the same time, the WC coating is characterized with the lowest friction coefficient and wear rate and the test is most smoothly, so the WC coating has the best tribological property in the low-speed test. The wear mechanism of ATS and ATB coating is the brittle fracture while the WC coating is the plastic deformation.5. In the high-speed wear test, the friction coefficient of all coatings is declined with the increase of load and speed but the developing trend of the wear rate is just different; Meanwhile the WC coating is characterized with the highest friction coefficient and wear rate and the vibration of the wear test is serious, so the WC coating has the worst tribological property in the high-speed test. The main wear mechanism of Al2O3-13%TiO2coating is adhesion wear and spalling wear; but the brittle fracture aroused by the propagation of the crack become more dominant in the WC coating. |
PDF Full Text Request