Study On The Technology Of Electroless Plating And The Properties Of Coating

The paper investigates the mechanism of Ni-P alloy and Ni-P-PTFE composite electroless plating codeposition , and the reaction thermodynamics and dynamics are analyzed. As for the problem of stability process of elcctroess Ni-P and Ni-P-PTFE composite electroless plating,all of the factors that influence the stability are studied in detail with methods of palladium chloride testing of electroless solution and stability constant. Based on the analysis of microhardness, adhesive strength, thickness, porosity and corrosion-resistant property of Ni-P alloy coating , the optimal process conditions of electroless plating are screened out, and the effects of complexing agent on Ni-P alloy coating is investigated by the contrast tests and orthogonal testing method. In the electroless solution, proper amount of PTFE dispersion and composite surfactant are employed, and stable Ni-P-PTFE composite electroless plating system are gained.The results show that, proper confection of electroless solution composition and proper choice of technical parameters have a direct influence on the stability of plating solution and coating properties, of which complexing agent and stabilizer are the most important factors. In the process of pre-treatment, plating surface must be clean otherwise affect adhesive; In the process of operation, temperature, pH value and mixing way are the main factors; In the process of continual operation, the supplement method and solution maintenance will decide the service life of electroless plating.Observing, the X-ray diffraction experiments support that the structure of the coating change from micro-crystal to amorphism with the increasing content of P in the alloy coating. And the content of P in the coating depend on the concentration of malic acid. Then will gain uniform dense coating by adding a proper amount of brightener.Adhesive and corrosion-resistant of coating are in line with the needs of industrial application by detecting properties of coating. The results clearly show minor abrasive wear under lubrication of Ni-P coating and adhere wear with high load under dry friction of Ni-P-PTFE coating by analyzing the microstructure of the grinding cracks.