镁锂合金无铬植酸化学转化膜研究  

A chromium-free chemical conversion coating for Mg-Li alloy by phytic acid solution

作　　者：高丽丽 张春红 张密林 黄晓梅 江溪 王兴璞 

机构地区：[1]哈尔滨工程大学材料科学与化学工程学院超轻材料与表面技术教育部重点实验室,黑龙江哈尔滨150001

出　　处：《功能材料》2008年第7期1134-1137,共4页Journal of Functional Materials

基　　金：国家自然科学基金资助项目(50603003)

摘　　要：为了提高镁锂合金的耐蚀性能,采用无毒植酸作为化学转化处理液对其进行表面处理。利用SEM和XRD对植酸转化膜的形貌及结构进行分析,测试结果表明植酸转化膜较均匀,并覆盖有白色不规则的花絮状颗粒。提出了镁锂合金在植酸转化处理液中的成膜机理,用开路电位时间曲线阐释化学转化成膜过程。通过极化曲线、析氢实验及点滴实验比较植酸转化膜与传统铬酸转化膜的性能。结果表明,与传统的铬酸化学转化相比,植酸转化后合金的腐蚀电位由初始的-1.65V提高至-1.40V,析氢速率也明显更小,说明植酸转化对改善镁锂合金的耐蚀性能更加有效。.An environment acceptable chromium-free process for Mg-Li alloy by phytic acid solution was developed, aiming at increasing the corrosion resistance of the alloy. The surface morphology, chemical structure of the conversion coatings were determined by scanning electron microscope （SEM） and X-ray diffraction （XRD）.The-results- showed--ihat there wet-e-some micro--cr-acks--in--the -homo-geneous p-hytic-acid c-onvers-ion-＇coatingTon which white flower-shaped substance was formed. In this paper, the formation mechanism of the Mg-Li alloy in phytic acid solution has been discussed. And the iormatlon process ot tne conversion coaung axia^y~eta uy LLa~ volution of the open circuit potential. The characters afforded by phytic acid and chromium acid conversion coat- ings on Mg-Li alloy had been studied using polarization curves, hydrogen evolution detection and drib experi- mentation. The results show that compared with the coatings formed in chromate solution, the corrosion poten- tial of Mg-Li alloy coated by phytic acid solution increased from -- 1.65-1.40V. In addition, the hydrogen evolution rate of the conversion alloy decreased obviously. It means phytic acid conversion can improve the corro- sion resistant of Mg-Li alloy more effectively.

关 键 词：镁锂合金 植酸 化学转化 耐蚀性 

分 类 号：TQ153.1[化学工程—电化学工业]