| The mechanical properties of the key engine parts need to be improved because of the rapid development of the automobile industry,the continuous increasing number of motor vehicles,technological progress as well as the continuous renewal of machine.Therefore,the requirements for performance of bearing materials as the key components of the engine continue to increase.The modification and research of bearing materials are studied by researchers to solve the contradiction between the performance of bearing bushes and the development of high-speed and high load engines.In this work,the process of hot-dip plating with Pb-Sn alloy plating and wear properties of the coating on Cu-based bearing bush were investigated,which is a positive effect in realizing the application of hot-dip plating on bearing material.Firstly,the Pb-Sn alloy coating was hot-dipped on the Cu substrate,and a suitable hot-dip coating process was obtained by analyzing the microstructure,phase composition and interface bonding strength of the coating.Then,Pb-Sn alloy coating and Pb-Sn-Cu coating on the friction and wear properties was studied,which can provide a theoretical basis for the application of hot-dip coating on bearing materials.The main contents and conclusions are as follows:1.The Pb-Sn alloy coating samples were prepared by different hot-dip plating processes,and it is found that a "sawtooth" diffusion layer is formed between the Cu substrate and the Pb-Sn alloy coating.The bonding strength between the Pb-Sn alloy plating layer and Cu matrix are good,which the hot-dip plating time is 20s and above.The macro morphology,microstructure,phase composition and interface bonding strength of the samples prepared by different hot-dip plating processes were analyzed.The hot-dip coating process in the subsequent tests of this study was determined,namely,pretreatment process,the hot-dip plating temperature and time are 280?and 30s,respectively.The coating obtained under this hot-dip coating process is smooth,free of slag,stable interface bonding strength and diffusion layer thickness.2.Pb-Sn/Cu reaction couple was established by the reaction between Cu and Sn during the hot-dip plating process,it is concluded that the growth of the diffusion layer phase satisfies the parabolic law by studying the interface diffusion kinetics of the Pb-Sn/Cu reaction couple.At the same time,the calculated value of the diffusion layer thickness was compared with the measured value,the obtained formula conforms to the growth law of the actual diffusion layer.3.Pb-Sn alloy coatings with different Sn contents were prepared,friction and wear experiments were carried out under the condition of oil lubrication,and it is concluded that as the anti-friction property of the coating increases and the wear resistance decreases with the increase of load.The anti-friction property of the coating increases and the wear resistance decreases with the increase of the Sn content.4.Pb-Sn-Cu alloy coatings with different Cu contents were prepared,subsequently,the microstructure of the coatings,the microstructure of the diffusion layer and the interfacial bonding strength between the coatings and the substrate were tested and analyzed.It is found that the addition of Cu can improve the interface bonding strength between the coating and substrate,and the critical load between the alloy coating and the substrate was increased from 21N to 36N.5.Adding Cu to the coating can effectively improve its anti-friction performance.The friction coefficient of the coating becomes small with the increase of Cu contents.When the copper content exceeds 2wt.%,the friction coefficient of the coating is less than that of pure Cu.The wear loss of the coating increases with the increase of the Cu content,but the increase speed gradually decreases.Compared with friction and wear morphology of pure Cu,the number of groove decrease,the width of the wear scar narrow and the friction surface of Pb-Sn-Cu alloy coating is relatively smooth with the increase of Cu content. |
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