Research On Microstructure And Properties Of Self-lubricating Cladding Coating For Remanufacturing Track Sprocket

Tracked vehicles have high mobility and strong off-road capability and are widely used.However,the tracked vehicles are under the harsh environment for a long time,which leads to the problems of wear and tear and corrosion of tracked sprockets.Therefore,this project is funded by the National Defense Science and Technology Key Laboratory Fund project "Nickel-based self-lubricating coating preparation process and shape control(JCKY61420052022)" and the key project of the Department of Education to prepare a layer of dense and good quality self-lubricating coating on the damaged tracked vehicle sprocket material by laser melting technology,In this paper,we aim to produce a dense and good quality self-lubricating coating on the sprocket material of damaged tracked vehicles by laser melting technique to further improve the reliability of tracked vehicles.In this paper,laser cladding tests were carried out in the context of repairing damaged tracked vehicle sprocket materials.Then,the self-lubricating coating process,organization and properties were discussed.The main research contents are as follows:(1)Firstly,the optimization method of self-lubricating melt coating process parameters is studied.In this paper,42 Cr Mo steel was used as the base material,nickel-clad graphite powder and Inconel718 powder as the coating powder,and the second-order central composite design(CCD)was used for the experimental design of laser melting single pass,and a coating comprehensive quality evaluation degree index system was established using hierarchical analysis.The response surface mathematical model of nickel-clad graphite content,laser power and scanning speed with the integrated quality of self-lubricating coating was established using Design-expert 10 software.The optimal combination of process parameters for the laser melting self-lubricating coating was obtained using adaptive variational particle swarm algorithm.(2)Nextly,the effect of process parameters on the organization and properties of selflubricating coatings was investigated.Testing of single-channel laser cladding was conducted by altering the graphite content of nickel coating,laser power,and scanning speed,all based on the combination of optimized process parameters.The microstructure and properties of self-lubricating coating were investigated in terms of the consequences of various process parameters.On this basis,multi-pass laser cladding tests were carried out to explore the changes of coating organization and properties under different lap rates.X-ray diffractometer(XRD),scanning electron microscope(SEM)and Vickers microhardness tester were used to characterize the phase,microstructure and properties of the coatings prepared under the optimal process parameter combination and response value.(3)Finally,the tribological properties of self-lubricating coating under different wear conditions were investigated.Using the obtained optimal lap rate for multi-track cladding experiments.The effects of different nickel-clad graphite content,working load,sliding speed and ambient temperature on the friction coefficient,wear weight loss,wear profile and wear surface morphology of nickel-clad graphite + Inconel 718 self-lubricating coating were investigated by using the obtained optimal lap rate for multi-pass fusion coating tests.The wear mechanism of laser cladding self-lubricating coatings under different wear conditions was analyzed.