Method for electroless plating of Ni-Co-P coating on magnesium alloy in acid solution

• Main Authors: HU FU, HU JIA, FANG LIANG, LI YUN, XIE LIANGBO
• Format: Patent
• Language: Chinese; English
• Published: 06.01.2010
• Subjects: CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; METALLURGY; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION

The invention relates to a method for electroless plating of Ni-Co-P coating on magnesium alloy in acid solution, which comprises the following steps: zincing after the magnesium alloy is pretreated and then carrying out electroless plating of Ni-Co-P. The method is characterized in that: during the electroless plating Ni-Co-P, the plating solution comprises the following components by weight: 10-20 g/L of nickel sulfate and 4-12 g/L of cobaltous sulfate as main salt, 8-20 g/L of sodium hypophosphite as a reducing agent, 13 g/L of sodium acetate as a buffering agent, 8 ml/L of HF (40 percent) and 8 g/L of NH4HF2 as a corrosion inhibitor, and 0 to 1mg/L of thiourea as a stabilizing agent, wherein the operating temperature is 77-87 DEG C, the PH value is 5 to 7, and the electroless plating time is 1.5-3 hours. The method has the advantages of uniform plating layer thickness, bright outer appearance, low porosity and good corrosion resisting property. Magnesium alloy castings after being plated with the Ni-Co-P