摘要
研究在硅酸盐溶液中添加K2CrO4对AZ91D镁合金微弧氧化膜耐蚀性的影响。结果表明:在含有K2CrO4的硅酸盐系溶液中进行微弧氧化处理的镁合金表面能够获得黄绿色的氧化膜层,主要由MgO、Mg2SiO4、MgAl2O4及MgCr2O4等耐蚀物相组成,其中具有尖晶石结构的MgCr2O4对提高膜层耐蚀性有极大的促进作用,同时它也是使膜层显色的物相;随着K2CrO4含量的增加,膜层厚度变化不明显,但颜色逐渐加深;并且膜层表面形貌表现出"火山堆"封闭微孔的微观特征;添加微量K2CrO4(0.4 g/L)可以显著提高膜层的耐蚀性,其腐蚀电流已减小至1.804×10-9 A/cm2,比基体的降低了4个数量级,而膜层的极化电阻已提高到2.04×107Ω/cm2,比基体的提高了5个数量级。
Effect of K2CrO4 as additive in silicate solution on corrosion resistance of micro-arc oxidation（MAO） coatings on AZ91D magnesium alloys was investigated.Results show that yellow-green coatings containing phases with good corrosion resistance such as MgO,Mg2SiO4,MgAl2O4,and MgCr2O4 were obtained on magnesium alloys processed in silicate solution including K2CrO4 additive.A new phase of MgCr2O4 with spinel structure contributed much to improvement of corrosion resistance of the coatings,and color display was also attributed to existence of MgCr2O4 phase in the coatings.With K2CrO4 dosage increasing,the changing of coating thickness was not obvious but the color of the coatings became deep green.A feature of some micropores covered by a heap-like vol-cano-shaped structure was observed on the coating surface.The corrosion resistance of the coatings was significantly improved with a small amount of K2CrO4 additive： just 0.4 g/L in the solution.Corresponding corrosion current of the coating in electrochemical test was dramatically reduced to 1.804 × 10–9 A/cm2,which was 4 orders lower than that of the substrate.The polarization resistance of the coating was also remarkably increased to 2.04 × 107 Ω/cm2,which was 5 orders higher than that of the substrate.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2011年第9期1493-1497,共5页
Journal of The Chinese Ceramic Society
基金
国家重点基础研究发展计划(2007CB613700)
人社部留学人员科技活动择优资助项目
关键词
铬酸钾
镁合金
添加剂
微弧氧化着色
耐蚀性
potassium chromate
magnesium alloy
additive
micro-arc oxidation coloring
corrosion resistance
