| Nowadays, it is a great challenge in the development of high-end technology and equipments that how to solve the solid lubrication problems of joints working in the conditions of high temperature and high contact stress. Silver layer is an ideal solid lubricant has as it has good lubricating properties at high temperatures. Also it has simple structures, easy to preparation, and good stability at high temperature. The traditional method of the preparation of low layer of silver film adhesion is easy to peel so as to limit its application in the conditions of heavy load and high temperature. Electron beam alloying technology with high energy density of electron beam bombardment to the sample surface, producing high temperature melt metallurgical bonding formation, improving the adhesion strength of the substrate and silver layer, to solve the lubricating problem of silver layer in the conditions of high temperature and heavy load.In this paper, first of all, the low energy pulse electron beam irradiation technology was adopted to clean M50 steel substrate surface, remove surface attachments and the low melting point oxides, and then to magnetron sputtering deposition due to the thickness of the silver layer, finally using high-energy pulsed electron beam of the deposition of silver layer surface for processing. Silver layer’s surface morphology was different by the means of adjustment of high-energy pulsed electron beam parameters, and the evolution mechanism of the silver layer surface morphology in the conditions of electron beam irradiation was studied. Friction wear test under heavy load and high temperature of magnetron sputtering silver layer and the layer after electron beam irradiation was performed to analyze friction properties and wear mechanism of the silver layer.Silver layer’s surface morphology evolution mechanism can be known when analysing surface morphology after electron beam irradiation. Electron beam irradiation surface morphology of the silver layer can be roughly divided into three categories by the means of SEM: complete continuous cover, mesh and scattered spherical structure. As was studied, the main influence factors of silver layer surface morphology after electron beam irradiation was the remaining quantity of silver surface. A certain thickness of the silver layer in the conditions of high energy density and multiple irradiation can produce melting and evaporation loss. As the amount of silver layer remaining changes from more to less, the morphology of silver varies from the complete continuous to dispersed spherical structure, the main driving force for forming silver surface was surface energy. The most stable state was the one of which surface energy was in the lowest status.Silver layer friction-wear test was performed in the conditions of high temperature(400/500/600℃)and high contact stress(2.0/2.5/3.0/3.5GPa). It turned out that the silver layer of M50 matrix disposed by magnetron sputtering deposition directly resulted in a large area of spalling due to poor film adhesion in the conditions of high temperature, and heavy load. Matrix of electron beam irradiation deposition of silver layer after cleaning had a long lubrication life which decreased with the increase of load and temperature and increased when the silver layer got thicker. Film adhesion increased at the same time and silver layer won’t produce flake. The silver layer had the longest lubrication life and lower friction coefficient when matrix was dealed with the low energy electron beam irradiation after cleaning and then disposed with high energy electron beam irradiation. The wear mechanism of silver layer was that extrusion between friction pairs and silver layer transfers silver to lateral of wear scar. The M50 matrix appeared gradually and silver layer lose efficacy in the end. Therefore, using pulsed electron beam irradiation technology can increase the lubrication life of silver layer in the conditions of high temperature and heavy load. |
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