(中國科學院 金屬研究所 金屬腐蝕與防護國家重點實驗室,
沈陽 110016)
摘 要: 將化學轉化和化學鍍鎳結合在一起，先對鑄態(tài)AZ91D合金進行錫酸鹽轉化處理，然后在轉化膜上進行化學鍍鎳。 研究了轉化膜及化學鍍鎳涂層的成分、 結構和耐腐蝕性能。 結果表明： 錫酸鹽轉化處理后合金表面形成了以MgSnO3·H2O為主要成分的轉化膜， 可對合金起到一定的防護作用；轉化膜由細小的球形顆粒密積而成， 顆粒之間存在間隙， 它可以為化學鍍鎳的前處理過程提供良好的吸附條件； 轉化膜上的化學鍍鎳層組織致密、 無缺陷， MgSnO3·H2O轉化膜在鍍鎳層與基體之間起到過渡作用， 鍍層的磷含量達到9%， 與基體結合良好； 在3.5% NaCl (pH=7)溶液中的動電位極化測試表明，鍍鎳以后的合金在陽極極化過程中發(fā)生了明顯的鈍化， 耐腐蝕性能進一步提高， 對基體起到了較好的防護作用。
關鍵字: 鎂合金； 化學轉化處理； 化學鍍鎳； 耐腐蝕性能
on corrosion resistance of magnesium alloy
（ State Key Laboratory for Corrosion and Protection,
Institute of Metal Research,
Chinese Academy of Sciences, Shenyang 110016, China）
Abstract: In order to improve the corrosion resistance of as cast AZ91D alloy, electroless nickel plating combined with chemical conversion treatment was investigated in detail. Firstly, the alloy was treated by stannate conversion treatment, and then electroless nickel plating was carried out on the conversion film. The compositions, structure and corrosion resistance of the conversion film and the electroless nickel coating were studied. The results show that a MgSnO3·H2O conversion film is formed by treatment in the stannate solution at 90℃, and the immersion test and potentiodynamic polarization show that the corrosion resistance of the AZ91D alloy is improved to some extent. The porous conversion film provides an advantage for the adsorption during sensitisation treatment prior to electroless nickel plating. A Ni-P coating is successfully deposited on the conversion film. The presence of the stannate conversion film reduces the potential difference between the Ni-P coating and the substrate and enhances the corrosion resistance of the coating. The potentiodynamic polarization indicates that the Ni-P coating deposited on the conversion film provides a good protection for the magnesium alloy.
Key words: magnesium alloy; chemical conversion treatment; electroless nickel plating; corrosion resistance
