Good corrosion resistance is the greatest advantage of hot galvanizing products, but people have higher and higher requirements on corrosion resistance of hot galvanizing products. At present, the commonly used methods to improve the corrosion resistance of hot-dip galvanized coatings include:
(1) increasing the thickness of t coatings.
(2) alloying to obtain zinc-ferroalloy coatings, which are significantly more resistant to corrosion than pure zinc coatings, and 7pum thick alloying coatings are equivalent to 10pm thick pure zinc coatings.3) improve the zinc liquid ingredients, in addition to the 70-80 - s of the 20th century development and commercialization of zinc - 5% A1 alloy plating (Galfan), people also developed a high corrosion resistance of zinc alloy key and special properties of the galvanized layer, such as zinc Al - 43.5% - 55% and 43.5% zinc alloy plating (Galvalume), may Al - 6% - 6% Mg will gold-bonded layer, zinc - Ni alloy plating
(3) and zinc magnesium alloy plating, etc. By improving the zinc liquid formula, has developed a high corrosion resistance than traditional plating 18 times of high corrosion resistant coating, and has been put into industrial production ,
(4) using two step hot dip method, first plated pure, second town with recent a1-6-0.5 Mg - 0.1 - Si alloy, can further improve the corrosion resistance of 1341, including alloying, also called plating, diffusion annealing treatment, early development. After the alloying treatment, not only the corrosion resistance increased, but also the welding performance and coating generation energy were greatly improved, so it was widely used in automobile, household appliances and other fields.
However, the development of Galvalume products in recent years has been decisive. Its key layer has higher corrosion resistance and beautiful surface, which is mainly used in architecture. In addition, the improvement of the composition of zinc solution and the effect on the addition of trace elements such as rare earth are still an important direction for the present study of %.