四硫鉬銨鹽對熱浸鍍鋅鋼板耐蝕性之作用

Effect of Ammonium Tetrathiomolybdate Salt on the Corrosion Resistance of Hot-Dipped Galvanized Steels

本研究以四硫鉬銨鹽[（NH4）2MoS4]為無鉻型處理劑對熱浸鍍鋅鋼片進行塗覆，並探討附著於鍍鋅鋼片的成膜型態及其耐蝕性質。實驗結果顯示經處理之熱浸鍍鋅鋼片表面，可獲得淡黃色含Mo-S化合物之膜層，該膜層之熱浸鍍鋅鋼片相較未處理之熱浸鍍鋅鋼片有較佳之耐蝕性。以FT-IR分析於880 cm-1有Mo-O特徵峰的存在；SEM分析皮膜與金屬之表面形貌；GDS分析其鉬、硫之膜重約0.051 g/m2，其元素之原子百分濃度比為Mo （0.95%）、S （3.23%）；極化曲線結果顯示含Mo-S膜層的鈍化較著重鍍鋅層反應的陽極過程；耐蝕性結果顯示含Mo-S膜層的熱浸鍍鋅鋼片於8小時內之鹽霧環境中無白銹生成。綜述其結果，在浸泡溶液濃度、反應時間等條件之調控下，藉由上述分析方法可確認四硫鉬酸鹽於鍍鋅鋼片上成膜之可行性及對耐蝕性有正面效益。

A non-chromate aqueous agent, ammonium tetrathiomolybdate, was coated on the surface of a hot-dipped galvanized steel (GI). Properties of the coating conformation and the corrosion resistance of the coated GI were studied. The results show that the corrosion resistance of the modified GI with a yellowish Mo-S coating layer was better than that of the GI without the coating layer. The FT-IR analysis disclosed the presence of Mo-O (880 cm-1). Scanning electron microscopy was used to analyze the morphologies of the coating layer and the metal surface. The results of glow discharge spectroscopy showed that the atomic percentages of Mo and S were 0.95% and 3.23%, respectively, with a total loading of Mo and S being 0.051 g/m2. Potentiodynamic polarization analyses showed that anodic passivation of the Mo-S layer occurred. In addition, no white rust was observed on the surface of the modified GI after an eight-hour salt spray test. By modifying the dipping solution concentration, dipping time and other parameters, the coating layer property of and the corrosion resistance of the modified GI would both be improved.