Electroless Ni-P deposition plus zinc phosphate coating on AZ91D magnesium alloy
Electroless Ni-P deposition plus zinc phosphate coating on AZ91D magnesium alloy
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DOI：
10.1016/j.surfcoat.2005.09.007
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发表时间：
2006-05-22
影响因子：
5.4
通讯作者：
Jiang, Q
中科院分区：
文献类型：
--
作者：
Lian, JS;Li, GY;Jiang, Q
采用化学镀Ni-P工艺对AZ 91 D镁合金表面进行防腐蚀处理。采用含磷化剂的锌系磷化液对AZ 91 D镁合金进行了磷化处理。然后在硫酸盐溶液中进行化学镀Ni-P。用XRD分析了磷化膜的物相组成。用SEM和EDS观察了磷化膜和化学镀Ni-P镀层的微观结构。结果表明，磷化膜中含有金属锌，在磷化液中加入钼酸钠可使锌含量增加。大量分散的金属锌颗粒为后续的Ni-P沉积起到了催化核的作用。结果表明，在添加2.0 ~ 2.5g/L钼酸钠的磷化液中，获得了组织致密、细小的Ni-P镀层。盐雾腐蚀试验结果表明，AZ 91 D镁合金表面的Ni-P+磷化膜具有良好的耐蚀性。(c)2005 Elsevier B. V.保留所有权利。
An electroless Ni-P deposition process has been developed to treat the AZ91D magnesium alloy surfaces against corrosion. Magnesium alloy AZ91D was first phosphatized in a zinc phosphating bath containing molybdate. Then an electroless Ni-P deposition was carried out on the phosphate coating from a sulfate solution. The phases in the phosphate coatings were analyzed by XRD. Microstructures of phosphate coatings and electroless Ni-P depositions were observed by SEM and EDS. It was found that there was metallic zinc in the phosphate coating and the addition of Na2MoO4 in the phosphating bath resulted in the increase of zinc in the coating. A lot of disperse metallic zinc particles acted as the catalyst nuclei for the succeeding Ni-P deposition. Consequently, the Ni-P depositions with dense and fine microstructure were obtained on the phosphate coatings gained from the phosphating bath wherein 2.0 similar to 2.5g/L Na2MoO4 was added. The Ni-P plus phosphate coatings on the AZ91D magnesium alloy exhibited acceptable corrosion resistance as shown by the results of the Salt Spray Corrosion Test. (c) 2005 Elsevier B.V. All rights reserved.