Wear Behavior Of Ni Coating By Brush Electro-Plating And Application On Recondition Of Ship Engine's Parts

As a specific branch, brush plating is a new development of electro plating technique. There are lots of advantages such as simple operating equipment, high current density, high deposit rate, good suitability and quality of coating etc. , therefore this technique has been widely applicated in surface engineering. The friction and wear behaviour is considered as one of the most important properties concerning the lifetime in the application. So it is necessary to study the friction and wear of brush plating coating to optimize the parameters of brush electro plating process.The samples with Ni coating have been prepared by brush electro-plating under different voltages. The friction and wear test has been conducted on the ball-disc friction test unit with a Cr12 pair on the condition of lubrication, and the performances of coating have been studied by means of wear loss, ferrography and surface morphology analysis.It was shown that the brush plating voltage and thickness of coating have a obvious influence on the surface morphology of coating: higher the voltage, distincter the micro-convex, and clearer the boundary; thicker the coating, more the micro-convex, and bigger the surface roughness.There are significant differences of friction and wear properties for the coating under different brush electro-plating voltages. The best correspandends to the voltage of 14V, and for the others the friction and wear properties reduce. The wear mechanism is abration and adhesion.The coatings under same brush electro-plating voltages with different thickness also show different friction and wear behaviour. The wear resistance decreases with thickness increasing, the best corresponds to the thickness of 100μm. The wear mechanism is also abration and adhesion.On the base of above test and analysis, the optimum brush eletro-plating voltage and thickness of coating to obtain the best wear resistance can be achieved, which provides an experimental basis for the practical application of brush electro-plating.Through the laboratory study, the above brush Ni plating process has been applied to the recondition of a transmission shaft, a marine diesel cooling jacket, and a serve motor piston surface. It was very satisfactory and successful for the recondition requirement by the fact that after one year operating the three reconditioned parts, transmission shaft, marine diesel cooling jacket and serve motor piston all function normally, the micro-structure is stable, the joining and wear resistance of coating is favorable.