Study On Composite Plating Coating Of Ni-P-nano Diamond Electroless On Magnesium Alloy

In recent years, with the increasing maturity of nanotechnology, nano-composite plating has attracted attentions from researchers home and abroad. By the legal system shelling principle of nanodiamond, it’s particle size usually fine with 20 nm,nano diamond not only has an unique nano-material physical and chemical properties while diamond has high hardness and high wear resistance characteristics, if nanodiamond can uniform deposition in the coating will greatly affect the chemical and physical properties of the coating surface properties, it can expand application rang of magnesium alloy.This article uses mature and stable high-temperature intermediately acidic of magnesium alloy plating Ni-P formulations, it can get low phosphorus content in plating, studies on the effect of pH value, temperature, reductant concentration on electroless plating Ni-P plating surface tissue surface morphology and mechanical properties. Select a group of excellent magnesium alloy Ni-P plating process parameters. The results showed that: pH value,temperature, reducing the concentration of Ni-P plating hardness has different factor, wherein the reducing agent concentration on the maximum hardness of the coating, pH value took the second place, followed by the minimum temperature. Because under high temperatures performance of the resulting coating was better, so the bath temperature control in the range of 14 ℃, within this range, the minimal impact temperature on the hardness of the coating.Within a certain range, with the hardness of the coating after the pH value and the reducing agent concentration first increased and then decreased. Orthogonal optimized Ni-P plating parameters: pH value of 6, the temperature(85 ± 2)℃, reductant concentration of 20g/L.Study on different heat treatment temperature of Ni-P coating surface morphology the influences, the results showed that when the heat treatment temperature reach the 350 ℃, the coating morphology flat, smooth, uniform, dense microstructure coating and maximum hardness.Adding different concentrations of nanodiamonds in Ni-P plating bath. Through the study of composite coating hardness testing and surface morphology, analyzed the effects of different concentrations and different nano-diamond composite coatings stirring speed on themechanical properties and microstructure morphology; composite coatings were 350 ℃ heat treatment, analysis composite coating structure and changes in mechanical properties;comparison before and after diamond coating was added friction coefficient of variation,detecting the wear resistance of composite coatings; coating by looking at the number of corrosion spots, testing the corrosion resistance of composite coatings. And the use of spectrum analysis, scanning electron microscopy, X-ray diffraction and other means of detection of the properties of the surface morphology of nanocomposite coatings, hardness,wear resistance and bonding strength were analyzed to find the best process. The results show that: with the increasing concentration of nano-diamond composite coating morphology gradually meliorates, when the amount of nano-diamond reaches 6g/L, various chemical plating solution to the state of relative balance, the resulting composite coating microstructure uniform and compact; stirring speed directly affects the absorption surface of the substrate nanoparticles when the stirring speed 200r/min, the best composite coating quality, continue to increase the speed of stirring, the nanoparticles produced aggregates; nanodiamond coating was added resulting in reduced friction coefficient and stable; Ni-P plated coating compared to chemical, Ni-P-nano-diamond composite coating corrosion fewer spots, enhanced corrosion resistance. Composite coating in high temperature heat treatment(300℃ above)during the coating structure consisting of amorphous to crystalline state, hardness markedly improved, if the temperature continues to rise, as a strengthening phase of Ni phase and Ni3 P phase to continue to grow the grain after the thick coating hardness lead to decline, affecting the mechanical properties of the coating.