The Performance Analysis Of N-SiC/Ni Composite Electro-brush Coating

Electro-brush plating, a specific branch, is a new development of electroplating. It has many advantages, e.g. simple operating equipment, flexible process, high deposit rate, various coating materials, high adhesive strength, widely usage, little pollution to environment etc.. Therefore it is a useful method for surface repairing and strengthening of mechanical parts. In recent years, nano-tech has been made great advance. The nano particles are mixed with electro-plating liquid to enhance the composite coating in order to meet with the high requirement of part performance.By the method of orthogonal design, sixteen samples with Ni coating are prepared by electro-brush plating under different voltage, liquid temperature and brush moving speed. Each of the three factors has four levels. Decide a better parameter by comparison as the foundation to mix with different density of n-SiC. Then compare these samples with the previous one.When the voltage changes from 8V,10V,12V to 14V, meanwhile the liquid temperature 50℃,55℃,60℃to 65℃, the brush moving speed 9 m/min,11 m/min,13 m/min tol5m/min, the roughness trends of these samples surfaces go down and up. The minimum roughness is when the parameters are set 10V,55℃,11 m/min by the roughness apparatus. The hardness of samples surfaces are rising with the voltages and the brush moving speed, using Vickers hardness gauge. But the maximum hardness is the liquid temperature set 60℃. In conclusion the selected liquid parameters are 10V,55℃,11 m/min.The SiC powder is ground to nanometer-sized using planetary ball mill, well distributed into the liquid. The density numbers are set 4 g/L,8g/L,12g/L,16g/L, 20g/L. Analysis the performances of these five samples, in contrast to the former Ni coating one and the foundation piece. Observation the topography after adhesive strength test, corrosion test and wear test using optical micrometer with CCD. Measure the roughness, friction factor, weight loss after wear using electronic balance. Because of the nano dimension and the high surface activity of n-SiC, the density either thick or thin makes negative influence on the coating performance. The selected n-SiC density is 8g/L.