Effect of copper-coated graphite on microstructure and properties of copper matrix brake pad
A chemical plating method was used to deposit copper on the surface of flake graphite to improve the interface bonding between graphite and copper matrix in copper matrix brake pads.The chemical copper plating formula and process were formulated,and the influence of four different plating bath temperatures on the copper plating effect was studied.The microstructure observation and energy spectrum analysis of the graphite after copper plating show that as the plating temperature increases,the copper plating quality first increases and then decreases,and the best plating temperature is 50 ℃.Copper-coated graphite/copper matrix brake pads(FM1)and non-copper-coated graphite/copper matrix brake pads(FM0)were prepared by hot pressing sintering method,their mechanical,physical,and braking performance were tested,and the surface morphology of the brake pads before and after braking was observed and analyzed using scanning electron microscopy and energy dispersive spectroscopy.The results show that compared with FM0,the graphite distribution in FM1 is finer and more uniform,resulting in a higher density of the sample,as well as an increase in hardness,compressive strength,and thermal conductivity.At different initial braking speeds,as the initial braking speed increases,the friction coefficients of both brake pads show a trend of first slightly increasing,then stabilizing,and then significantly decreasing.However,the friction coefficient of FM1 is generally higher and more stable than that of FM0,and the linear wear rate is relatively small.Under high-speed braking conditions of 350 km/h,due to the softening of the material surface caused by frictional heat,the friction coefficients of the two brake pads are not significantly different and both show a significant downward trend.
copper-coated graphiteelectroless copper platingcopper matrix braking padplating temperaturecoefficient of friction(COF)