Research On The Performance Of Laser Cladding Nickel-based Chromium Carbide Coating For Automobile Piston Ring

The working environment of automobile piston ring is harsh and severe,and with the development of automobile industry,the failure of piston ring is becoming more and more prominent.In recent years,the application of laser cladding in improving the performance of metal surface has been developed rapidly.Because of its unique advantages,it has received extensive attention and research.The research is based on cladding materials composed with nickel-based alloy and Cr3C2 powder,which are mixed by mechanical method.4Cr5MoV1Si(H13)steel is used as substrate material.Coaxial feeding is selected to carry out the laser cladding experiments.In order to put up with a more suitable choice for improving the surface performance of automobile piston rings,studying the influence between different process parameters of laser cladding and microstructure and performance of composite materials cladding.The main research contents are as follows:(1)Using the central composite design test plan belonging to the response surface method,the laser cladding process parameters(laser power,scanning speed and feeding rate)are studied.According to the prediction model for the optimized combination,the process parameters are determined:laser power P is 376W,scanning speed v is 4.5mm/s,feeding rate f is 0.7r/min.Single cladding with nickel-based alloy is prepared.By studying the overlapping rate,scan mode and the Z axis lifting value,a rate of 0.22,track mode for both-way track and a lifting value of 0.642 mm for the multiple overlapping and overlaying cladding test is more appropriate,which is used to prepare nickel-based alloy multiple overlapping and overlaying cladding.(2)Nickel-based chromium carbide composite materials coating was prepared,and the addition of CrsC2 is 15%,17%,19%,21%,23%and 25%respectively.The macroscopic appearance of each coating is good,without obvious defects.The microstructure is compact and complete.Coating and substrate are formed wih the metallurgical combination of "white band",the organization structure from the substrate to the top of cladding coating is planar crystal?columnar dendrites?the equiaxial dendrites.The main content of composite materials coating consists of three phases:Cr-Ni-Fe-C solid solution,Cr23C6 carbide and Cr7C3 carbide.The microhardness of composite materials coating is 2-3 times higher than the microhardness of the substrate.The residual stress at the same location of the composite materials coating is similar.The stress of the center position is larger,and the stress of the thermal influence zone on the surface edge of the substrate is smaller.(3)Combined with the working condition of piston ring,the test for the coating performance is completed.Under the same conditions,the composite materials coating is used for dry friction wear test.The wear volume and average friction coefficient decrease with the increase of Cr3C2 addition,and the anti-friction property is improved accordingly.Friction process belongs to abrasive wear,and there are two kinds of wear mechanism of plastic deformation and cutting,fracture and peeling.At setted temperatures,the composite materials coating has been tested for prolonged high temperature oxidation.The coating with 21%and 25%Cr3C2 addition has better high temperature oxidation performance.The diffraction atlas is composed of the diffraction peaks of Cr2O3 oxide and FeNi alloy.