Study On The Effect Of Rare Earth On Ni-P-PTFE Composite Electroless Plating And Clad Layer

Being their homogeneity excellent corrosion resistance, anti-wear, weldability and other special electric and magnetic properties,electroless plating deposits have widely been applied to electronics, prtroleum,chemistry,aerospace,nuclear, automobile,printing,textile,machinery and so on. The paper investigates the mechanism of Ni-P alloy and Ni-P-PTFE composite electro less plating co deposition . Based on the presaid mechanism, the effect of rare earth on the Ni-P-PTFE processing and coatings'performance is studied. Besides, the reaction thermodynamics and dynamics are analyzed. The effects of complexion agent and the concentration radio of main salt and reducer on Ni-P alloy coating are investigated by the contrast tests and orthogonal testing method. It is shown that fast deposition rate and well stability can be obtained when the concentration radio of main salt and reducer is 0.4. On that basis , in the electroless solution, proper amount of PTFE latex and chloride of rare earth are added.Through the analysis of microhardness, adhesive strength, deposition rate, porosity and corrosion-resistant property, the optimal process conditions of electroless plating are screened out and well composite coatings 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. 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.Coatings'surface topography and composition are characterized by means of Scanning Electron Microscope(SEM) and energy dispersive x-ray spectroscopy(EDS). It is found that 2mg/L rare earth(RE) can make the thickness of the coatings thicker and more even than that of without RE. However, continuing appending RE in the bath, the coatings kemel begin to largen. On the view of macroscopic , coatings'surface topography is brightener than that of without RE. The thesis focuses on the effect of chloride of rare earth on Ni-P alloy coating and Ni-P-PTFE composite coatings'corrosion-resistant, micro hardness and deposition rate. The results shows that right amount of rare earth can improve deposition rate, stabilize the bath and enhance coatings'hardness .When the acceding content of rare earth in the bath is 2mg/L, Ni-P-PTFE coatings'corrosion-resistant and hardness each increased by one time. Further increase in concentration of rare earth leads to augment the coating's porosity and results in the decrease of corrosion resistant.