鋁鋅複合噴覆塗層對AZ31鎂合金表面性質之影響

Effect of Aluminum / Zinc Double-Layer Spray Coating on the Surface Properties of AZ31 Alloy

本研究探討鋁鋅複合塗層對鎂合金AZ31板材表面結構、腐蝕特性及機械性質等之影響。以火焰熔射披覆上一層純鋅（80 µm）再以電弧噴覆披覆上一層鋁塗層（170 µm），以形成三明治之結構，並研究加壓處理及鋁陽極處理等後處理之影響。由實驗結果可知AZ31鎂板經鋁鋅噴覆後，其在3.5wt% NaCl水溶液下極化曲線之腐蝕電流密度由2.00 10-6A/cm2升高至1.00 × 10-4 A/cm2。但經298K下2000MPa壓力處理之試片，其變形率約為7.07%，表面粗糙度為2.9 µm及腐蝕流密度降低至6.58 × 10-7 A/cm2，可發現加壓處理有效使表面鋁新噴覆層緻密化，減少溶液經孔洞直接接觸鎂基材而造成伽凡尼腐蝕效應，以利後續之陽極處理。鋁鋅噴覆AZ31鎂板經298K及2000MPa壓力施壓10分鐘後，進行7wt%草酸陽極處理，能在鋁塗層表面形成氧化鋁膜，其試片之腐蝕電流密度為1.05 × 10-8 A/cm2，顯示鋁鋅噴覆AZ31鎂板經加壓及陽極處理後，能有效提升抗蝕性。

The influence of aluminum / zinc double-layer spray coating, pressing and anodizing treatment on the corrosion resistance of AZ31 magnesium alloy has been investigated. From the experimental results, the optimal pressing condition, conducting in the 2000 MPa at 298K, resulted in the combination of the deformation strain of 7.07 %, the surface roughness value of 2.9 µm and the corrosion current density of 6.58 10-7A / cm2. The electrochemical test shows the pressing treatment can improve the corrosion resistance of aluminum / zinc double-layer sprayed AZ31 specimen. When the aluminum / zinc double-layer sprayed AZ31 plate was pressed and then anodized, an anodized layer was formed in the specimen and its corrosion current density of the anodized specimen in a 3.5wt % NaCl solution was further decreased to 1.05 10-8 A/cm2 .