Effect of Colloidal Stability of Diamond Nanoparticles on the Ni-W/Diamond Electro-co-deposition Composite Coatings and Evaluation of Corrosion Resistance

摘要

Ni/diamond composite coatings can be produced by co-deposition of nickelungsten matrix withmicro-sized diamond particles under direct current (DC) from aqueous citrate electrolytes in whichdiamond particles are dispersed. The present study investigated the effect of pH value on thedispersion stability of diamond particles in a suspension and deposition behavior of diamond particlesin composite electroplating. Increasing the electrolyte pH caused an increase of co-deposited diamondparticles within the present experimental range. At pH = 8.5, the maximum volume percentage of theembedded diamond particles in composite coating was obtained. In addition, the current efficiency anddeposition rate increased. The tungsten content of the composite coating, however, decreased withincreasing pH value of the plating bath during electroplating process. The anodic polarization curveswere implemented to evaluate the corrosion behavior of Ni alloy and Ni/diamond compositecoatings. The analysis shows that Ni/diamond composite coating has better corrosion resistance.