Mechanism And Application Of Plasma Sprayed Nickel Alloy In Surface Repair Of Crankshaft

The crankshaft is an important part of an automobile engine,and its quality directly affects the working performance of the engine.During the long-term operation of the crankshaft,it will be affected by the forces from various components,reducing its working accuracy and causing failure.In order to ensure the working performance of the crankshaft and improve economic efficiency,it is very necessary to repair it.This paper uses plasma spraying technology to spray nickel-based composite coating on the damaged crankshaft surface to repair it.Firstly,the coating test scheme is designed using uniform design,and then a nickel-based composite coating with high microhardness and self-lubricating properties is sprayed on the surface of 45 steel,a common material for crankshafts.The coating is divided into three groups.The first group adds CNTs,TiN,Cr₂O₃,and CeO₂ to the Ni_60A0A alloy powder to form an alloy coating;the second group adds TiN,Cr₂O₃,and CeO₂ powder to the Ni_60A0A alloy powder to form a wear-resistant composite coating;The third group added CNTs,Cr₂O₃,CeO₂powder to the Ni60A alloy powder to form a self-lubricating composite coating.Then use the HV-1000 universal hardness tester to test the hardness of the coating cross section to measure the microhardness of the coating;use the MDW-02 reciprocating friction and wear testing machine to perform the wear test on the coating surface to measure the friction coefficient and the amount of wear;use XRD to conduct phase analysis on the coating surface to determine the composition of the composite phase in the coating;use SEM to analyze the microstructure of the coating cross-section to determine the microstructure of the coating cross-section;Use EDS to perform elemental analysis on the coating cross-section to determine the distribution of each element on the coating surface.Finally,the artificial neural network method is used to optimize the calculation of microhardness,friction coefficient and wear,and to determine the mass fraction ratio of each component when the overall performance of the coating is good.The research results show that:in the nickel-based Cr₂O₃,TiN,and CeO₂composite coating,the nickel-based 35%Cr₂O₃,40%TiN,and 2.5%CeO₂ coating has a higher microhardness of 3263.33HV,a lower friction coefficient of 0.333,and a higher wear amount of 1.2mg,because the hard phase content of Cr₂O₃ and TiN is higher,and the content of CeO₂ is also higher,which improves the structure of the coating;In nickel-based CNTs,TiN,CeO₂ coating,the nickel-based 1%CNTs,30%Cr₂O₃,and 2%CeO₂ coatings have a higher microhardness of 2419.5HV,a lower friction coefficient of0.253,and a smaller wear amount of 1.2mg,because CNTs is lower,Cr₂O₃ hard phase content is higher,and CeO₂ content is also higher,the self-lubricating performance of the coating is better,and the microhardness is higher.