热浸Zn-Ti合金镀层的显微组织与耐蚀性能

为了抑制热镀锌过程中因含硅活性钢引起的镀层超厚生长，本文采用在纯锌浴中加Ti的方法，研究了0.09%Si钢在含低于0.1%Ti的几种锌浴中热浸镀获得的组织，并采用盐雾腐蚀，电化学极化以及X射线光电子能谱等方法，研究了Zn和Zn-Ti镀层的耐蚀性能。结果表明，随着锌浴中Ti含量的增加，Ti对ζ相生长的抑制作用增强，合金层厚度逐渐减薄，Ti能有效地抑制含硅活性钢镀层的超厚生长。当Ti含量大于0.05%时，镀层中出现Γ2粒子。Zn-Ti合金镀层在5%NaCl溶液中发生自发腐蚀的倾向小于Zn镀层，其极化电阻增大，腐蚀电流密度减小，耐蚀性能提高。Zn-Ti镀层表面形成的氧化膜由ZnO 和TiO2组成。锌钛合金镀层的耐腐蚀性能优于纯锌镀层是由于在镀层表面形成了更加稳定的TiO2膜。

Microstructure and corrosion resistance of hot dip Zn-Ti coating

Zn-Ti coatings were prepared on steel containing 0.09%Si by hot dip galvanizing in Zn-Ti baths. The influence of titanium on the microstructure of the coatings was investigated, and the corrosion resistance of the coatings was studied by neutral salt spray test (NSS), electrochemical polarization and X-ray photoelectron spectrum (XPS) analysis. The results show that, with the titanium content in the zinc bath increases, the growth of ζ phase in coating is restrained obviously, the thickness of coating decreases. Titanium can effectively restrain the excess growth of coating induced by reactive steel containing silicon during the hot dip galvanizing process. When the titanium content in the zinc bath is over 0.05%, the Γ2 phase particles are formed in the coating. The Zn-Ti coating shows lower corrosion current, larger polarization resistance, less spontaneous corrosion tendency in 5% NaCl solution and better corrosion resistance than those of pure zinc coating. The oxidized film of Zn-Ti coating is composed of ZnO and TiO2. The excellent corrosion resistance of Zn-Ti coating results from the reason that the present of steadier TiO2 film.