摘要
Abstract
Objective To investigate the effect of rare-earth element lanthanum on the corrosion resistance of zinc layer. Methods In this paper, lanthanum oxide, sulfuric acid lanthanum, as well as lanthanum chloride and lanthanum nitrate were added into zinc powder respectively, with an additive-free control, and the corresponding zinc layers were prepared by embedding method. The thickness and surface morphology of the zinc layers were studied by coating thickness gauge (model:TT260) and scanning electron microscope ( SEM) , respectively. Full immersion corrosion experiment was carried out in 5% ( mass fraction) NaCl solution, the 75 h and 150 h corrosion weight loss was measured by TG-328-A analytical balance measurement, and the corrosion morphology was observed by digital microscope. Results The effects of rare-earth element lanthanum on the thicknesses, surface morphology and corrosion resistance of zinc layers were compared. The results showed that the thickness of zinc layer was 33. 0 μm for the ad-ditive-free control, 45. 7 μm for lanthanum oxide, 41. 7 μm for sulfuric acid lanthanum, 36. 1 μm for lanthanum chloride, and 43. 1 μm for lanthanum nitrate. Zinc layer with lanthanum oxide had the optimal surface morphology, but a few micro cracks oc-curred on the surface. In salt water immersion test, the corrosion weight loss rates of zinc layer with lanthanum nitrate were the smallest both at 75 h and 150 h, which were 0. 0441 g/(m2·h) and 0. 0625 g/(m2·h), respectively, showing the excellent corrosion resistance. Conclusion Addition of rare-earth element lanthanum into zinc powder improved the efficiency of zinc impreg-nation, making the surface of zinc layer uniform and compact, but a few micro cracks appeared on the surface. The effects of lan-thanum oxide, acid lanthanum and lanthanum nitrate on the efficiency of zinc layer were obvious, but lanthanum chloride showed the least effect. In salt water environment, the effect of lanthanum chloride on the corrosion resistance of zinc layer was the least, while lanthanum nitrate had the best effect.关键词
稀土/不同化合物/渗锌/渗层厚度/表面形貌/耐蚀性Key words
rare earth/different compounds/sherardizing/thickness of zinc layer/surface morphology/corrosion resistance分类
矿业与冶金
