ABSTRACT
In order to meet the performance requirements, the bearing is gradually developed from single alloy bearing to multilayer composite bearing. The bearing coating plays an important role in improving the performance requirement. The bearing coating is mainly divided into electroplated coating and sputtering coating. Because of containing Pb, the production process of electroplated coating is high pollution. Though the lead free electroplated coating has been developed, this coating’s wear and fatigue is still worse than sputtering coating. The current sputtering coating is mainly produced with single alloy target. The cost of single alloy target sputtering is expensive. In sputtering process, the alloy elements with difference sputtering rate and the elements of coating is missing, or the content of some elements decreases. So the content of coating is different from the alloy target. The controllability of single alloy sputtering coating is poor, it restrict the industrial production and application of the sputtering bearing coating.
In this paper, Al-Sn-Cu wear-resistant coatings were prepared by the ultra-high vacuum magnetron FJL560D2 type with multi-ion-beam sputtering equipment, In order to control of the coating composition, three target co-sputtering was used with purity 99.99% Al, Sn and Cu sputtering targets, and sputtering processes could be independently adjusted .
In the preparation of Al-Sn-Cu resistant coating, sputtering pressure were investigated for the 0.5Pa, 1.0Pa and 1.5Pa, sputtering time of 2h, 3h and 5h, sputtering power ratio of 2:1,3:1, and 4:1 and different preparation conditions such as post-coating heat treatment conditions. Microstructure and surface morphology of Al-Sn-Cu coating were analyzed by XRD, AFM, and SEM etc. And the mechanical properties and corrosion resistance of coating were studied by HX-1000 type micro-hardness tester, WS- 2005 automatic scratch coating adhesion instrument, CHI electrochemical analyzer. The influence of the preparation process on microstructure and properties were revealed.
The element atomic ratio is consistent with the sputtering power ratio. The sputtering coating composition is achieved controllable. By adding Cu element in the coating, the hardness of Al-Sn-Cu coating is better than Al-Sn coating. It is improved the load and wear resistance coating.
As the sputtering pressure increase, the particle size of the coating surface decreases,the uniformity of the coating surface decreases, the hardness of coating decreases fist and then increases. When the sputtering pressure is 1.0Pa, the hardness of coating is lowest. As the sputtering time increases, the coating hardness decreased. By adjusting the sputtering process AlSn power ratio found with AlSn power ratio increases, the coating increases, the ratio of the AlSn sputtering power is low, the prepared coating hardness. Different heat treatment conditions and properties of the coating influenced, directly heat the substrate during sputtering can effectively improve the strength of the crystallization of the coating and reduce the hardness of the coating, and vacuum annealing of the coating can significantly improve the coating and substrate binding force. The prepared coating, Al atoms in cubic close stacking structure, Sn in the coating to α-Sn phase present, Sn atoms closely packed square structure, Cu atoms close to cubic structure accumulation. Adjust the process parameters so that the coating structure is not changed significantly. Coated particles in the growth are related with the base materials, pure growth of the Cu substrate coated grains, arranged in compact. And 10# steel as base material coating the surface of the particle size is inconsistent, there will be significant within the local area grew up in the coating particles.
KEY WORDS：Al-Sn-Cu coating, sputtering, bearing coatings, mechanical properties
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