2A12铝合金锆基转化膜的制备及性能研究

Preparation and Properties of Zr-based Conversion Coating on 2A12 Al-alloy

在2A12铝合金基体上制备了无铬锆基转化膜,对锆基转化膜的耐腐蚀性能、前处理及成膜过程中的显微形貌演变和膜层成分进行了表征,重点探究了第二相对成膜过程的影响。结果表明,基体表面第二相对锆基转化膜成膜的影响主要体现在三方面:第一,碱洗和酸洗前处理后,合金表面第二相和大量蚀坑的存在造成基体表面凹凸不平;第二,成膜过程中,第二相的存在不利于转化膜颗粒的均匀形核和长大;第三,成膜完成后,第二相被腐蚀破坏,严重影响膜层的致密性和均匀性。

A Cr-free Zr-based conversion coating(ZrCC)was prepared on 2 A12 Al-alloy,which then was characterized in terms of the surface micromorphology evolution and composition of 2 A12 Al-alloy during pretreatment and conversion process,especially,the influence of the second phase of the alloy on the conversion process.The results show that first,the pretreatment process resulted in a very rough surface of the 2 A12 Al-alloy,on which there exist many pits and residual second phases;next,the second phase particulates in 2 A12 Al-alloy were unfavorable to the uniform nucleation and growth of conversion coating granulates during conversion process;and third,after conversion process,the second phase particulates on the 2 A12 Al-alloy surface were seriously destroyed,that brough strong impact on the compactness and uniformity of the coating.