Direct electroless Ni-P deposition on AM50 magnesium alloy from sulfate bath
(1.吉林省长春市吉林大学材料科学与工程学院教育部汽车材料重点实验室2.浙江省温州市浙江工贸职业技术学院先进材料研究发展中心3.吉林省长春市吉林大学汽车材料系材料科学与工程系重点实验室4.Key Laboratory of Automobile Materials, Ministry of Education, College of Materials Science and Engineering, Jilin University, Changchun 130025, China)
Abstract: A bright electroless Ni-P deposition on AM50 magnesium alloy in a sulfate plating bath was proposed by using direct plating process with non-chromate pretreatment. The electroless Ni-P plating on AM50 magnesium alloy has an admirable appearance and good adhesion. The results indicate that the electroless Ni-P deposition with non-chromate pretreatment has better adhesion than that of zinc immersion coating. Anodic polarization curves indicate that the electroless Ni-P deposition obtained from the sulfate bath has similar corrosion-resistance to that obtained from basic nickel carbonate bath. The deposition process generates less pollutant by a non-chromate plating bath and is suitable for the magnesium alloys manufacture because of its low cost. The hardness of the electroless Ni-P plated AM50 is about HV 720.6 and HV 969.7 after heat treatments at 180 ℃ for 2 h. The wear resistance of Ni-P plated magnesium alloy specimens is about 5 to 9 times as high as that of bare magnesium alloys.
Key words: magnesium alloy; AM50; Ni-P deposition; salt spray, adhesion