关键词: Ni-P镀层 , 硫脲 , 孔隙率 , 腐蚀性

Abstract: The thiourea was added in the electroless plating solution to analyze the influence of thiourea on the Ni-P coating deposition rate, surface morphology and porosity, etc.. The corrosion resistance was evaluated through polarization curves and electrochemical impedance spectroscopy. The results show that when 1 mg/L thiourea in the electroless plating solution was added, the deposition rate of coating accelerates and the corrosion rate increases. This is mainly reason after thiourea was added in the electroless plating solution, the porosity of coating increases, which promote the corrosive medium to seep deeply into the surface of the substrate resulting in increasing the number of corrosion micro cells and forming a corrosion cell of the large cathode(coating)-the small anode (substrate). The corrosion current density increases and the charge transfer resistance reduces. While thiourea was added more than 3 mg/L, the electroless plating solution is poisoned and unable to plating.

Key words: Ni-P coating,    ,  Thiourea,    , Porosity,    , Corrosion resistance