High corrosion resistance of electroless Ni-P with chromium-free conversion pre-treatments on AZ91D magnesium alloy  

无铬转化膜预处理提高AZ91D镁合金化学镀Ni-P的腐蚀性能(英文)

作　　者：J.SUDAGAR 连建设[1] 陈晓明[1] 朗鹏[1] 梁亚琴[1] 

机构地区：[1]吉林大学材料科学与工程学院(南岭校区)教育部汽车材料重点实验室,长春130025

出　　处：《Transactions of Nonferrous Metals Society of China》2011年第4期921-928,共8页中国有色金属学报（英文版）

基　　金：Project(50871046)supported by the National Natural Science Foundation of China;Project(2010CB631001)supported by the National Basic Research Program of China;Project supported by the Program for Changjiang Scholars and Innovative Research Team inUniversity,China;Indo-China cultural exchange scholarship program by the Ministry of Human Resource Department(MHRD,India)and Ministry of Education(MOE,China)

摘　　要：Phosphate-manganese, tannic acid and vanadium conversion coatings were proposed as an effective pre-treatment layer between electroless Ni-P coating and AZ91D magnesium alloy substrate to replace the traditional chromate plus HF pre-treatment. The electrochemical results show that the chrome-free coatings plus electroless Ni-P coating on the magnesium alloy has the lowest corrosion current density and most positive corrosion potential compared with chromate plus electroless Ni-P coating on the magnesium alloy. These proposed pre-treatment layers on the substrate reduce the corrosion of magnesium during plating process, and reduce the potential difference between the matrix and the second phase. Thus, an electroless Ni-P coating with fine crystalline and dense structure was obtained, with preferential phosphorus content, low porosity, good corrosion-resistance and strengthened adhesion than the chromate plus electroless Ni-P.在化学镀Ni-P层和AZ91D镁合金之间生成磷酸锰、单宁酸或钒转化膜预处理层,以取代传统的铬酸盐加氢氟酸预处理工艺。电化学测试结果表明:与传统的铬酸盐处理加化学镀相比,镁合金上的无铬转化膜加化学镀镍磷具有低的腐蚀电流密度和更正的腐蚀电位,能够减少基体上化学镀层的腐蚀。因此,镀层具有致密的细晶结构,适当的磷含量、低孔隙度和良好的耐蚀性并且和基体结合良好的涂层可以取代传统的铬酐钝化加化学镀的工艺。

关 键 词：magnesium alloy corrosion resistance ELECTROLESS chromium-free pre-treatment 

分 类 号：TG174.4[金属学及工艺—金属表面处理]