Influence of surface pretreatment on phosphate conversion coating on AZ91 Mg alloy

SURFACE & COATINGS TECHNOLOGY

卷:359

Article

Zhang, Chunyan^1,2  Liu, Bin¹  Yu, Baoxing²  Lu, Xiaopeng³  Wei, Yong¹  Zhang, Tao^1,2,3  Mol, J. M. C.⁴  Wang, Fuhui³ 

[1] Harbin Engn Univ, Corros & Protect Lab, Key Lab Superlight Mat & Surface Technol, Minist Educ, Nantong ST 145, Harbin 150001, Heilongjiang, Peoples R China

[2] Inst Met Sci & Technol, Corros & Protect Div, Shenyang Natl Lab Mat Sci, Shenyang 110016, Peoples R China

[3] Northeastern Univ, Corros & Protect Div, Shenyang Natl Lab Mat Sci, 3-11 Wenhua Rd, Shenyang 110819, Liaoning, Peoples R China

[4] Delft Univ Technol, Dept Mat Sci & Engn, Mekelweg 2, NL-2628 CD Delft, Netherlands

关键词: Mg alloy;    Phosphate conversion coating;    Surface pretreatment;    Corrosion protection;   

DOI  :  10.1016/j.surfcoat.2018.12.091

来源: Elsevier

【 摘 要 】

Surface pretreatment is generally applied before application of protective coatings on Mg alloys, which influences surface microstructure and electrochemical activity of the substrate and has an effect on the coating properties. The effect of various pretreatment processes (sand-blasting, grinding and polishing) on the micro-structure and corrosion protection performance of phosphate conversion coating (PCC) on AZ91D Mg alloy was investigated in the present study. Sand-blasting cleaning significantly increases the surface roughness and electrochemical activity of the substrate, leading to formation of a porous PCC with inferior corrosion protection performance. In the case of ground/polished Mg alloy, the uniformity and corrosion resistance of the resultant conversion coating are mainly related to the surface roughness. Relatively low surface roughness of the substrate facilitates formation of a corrosion protective PCC.

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