外文翻译--用自由铬预先处理在AZ91D镁合金上电镀NI－P层英文版.pdfVIP

Surface Coatings Technology 201 (2007) 4594 – 4600 /locate/surfcoat Electroless Ni–P layer with a chromium-free pretreatment on AZ91D magnesium alloy W.X. Zhang, J.G. He, Z.H. Jiang, Q. Jiang, J.S. Lian ⁎ Key Laboratory of Automobile Materials (Jilin University), Ministry of Education, Changchun 130025, China Department of Materials Science and Engineering, Jilin University, Changchun 130025, China Received 1 July 2006; accepted in revised form 28 September 2006 Available online 27 November 2006 Abstract A phosphate-manganese conversion film was proposed as the pretreatment layer between Ni–P coating and AZ91D magnesium alloy substrate, to replace the traditional chromium oxide plus HF pretreatment. The subsequent Ni–P deposited on the layer was also characterized by its structure, morphology, microhardness and corrosion-resistance. The pretreatment layer on the substrate not only reduces the corrosion of magnesium during Ni–P plating process, but also reduces the potential difference between the matrix and the second phase. Thus, a Ni–P coating with fine and dense structure was obtained on the AZ91D magnesium alloy, which shows better corrosion resistance than the Ni–P with chromium oxide plus HF as pretreatment. © 2006 Elsevier B.V. All rights reserved. Keywords: Chromium-free pretreatment; Magnesium alloy; Corrosion resistance 1. Introduction technique is that good quality deposits with uniformity can be