Preparation And Wear Mechanism Of Anti-wear Thick Coating On Cu-based Self-lubricating Surface

In this paper,a Cu-based self-lubricating and wear-resistant thick coating with Ni as transitional bonding layer is prepared on the surface of 45 steel by hot pressing sintering process.The effects of carbon fiber,graphite and different contents of nano-TiO₂ and nano-Al₂O₃ on the anti-wear properties of Cu-based self-lubricating wear-resistant coating is studied.The wear mechanism of the wear-resistant coating is analyzed.A numerical wear model is established.The main contents and conclusions are listed below.The preparation route and method of Cu-based self-lubricating and wear-resistant thick coating are established.The sintering process parameters is determined as follows:sintering temperature was 850?,pressure was 30 MPa,holding for 40 minutes,and finally the sample was cooled to room temperature with the furnace.According to the technological route and preparation method,the copper-based self-lubricating and wear-resistant thick coating is finally prepared.The carbon fiber and graphite are evenly distributed in the Cu-based self-lubricating wear-resistant coating.The microstructure of the coating is dense and the interface between the coatings is bonded well.The addition of carbon fiber enhances the hardness and improves the coefficient of friction and wear rate of the coating.Graphite is added as a lubricant to further reduce the friction coefficient and wear rate of the coating,but it reduces the hardness of the coating.Carbon fiber and graphite facilitate the formation of a lubricating film,so that the prepared material has a small wear rate.Two kinds of Cu-based self-lubricating wear-resistant coatings with nano-TiO₂ and nano-Al₂O₃ are studied.The microstructure of the two coatings are dense.The nano-TiO₂ and nano-Al₂O₃ are evenly distributed in the coating,and the interface between the coatings is bonded well.The hardness of 3wt.%nano-TiO₂ and nano-Al₂O₃ Cu-based coatings is the largest.Under dry sliding friction,both of them exhibit the best anti-wear performance.The wear mechanism is based on the formation of lubricating film and abrasive wear.The Cu-based coatings without nano-TiO₂ and nano-Al₂O₃ have adhesive wear,and the latter also have peeling of the transfer film,slight ploughing and plastic deformation.The wear mechanism of 1wt.%nano-TiO₂ and nano-Al₂O₃ Cu-based coatings is mainly plastic deformation and fatigue spalling of a small amount of lubricating film.Adhesive wear and ploughing occurred in both 5wt.%nano-TiO₂ and nano-Al₂O₃ Cu-based coatings.The influence of external and internal factors on wear during friction was systematically analyzed.Based on the principle of dimension analysis and the application of MATLAB software,a wear numerical model for anti-wear thick coating on cu-based self-lubricating was established.The numerical introduction of the wear model is in good agreement with the actual wear.