The study on corrosion resistance and surface quality
of coatings is the greatest advantage of hot-dip galvanized products, but people have higher and higher requirements on corrosion resistance of hot-dip galvanized products.
At present, the commonly used methods to improve the corrosion resistance of hot-dip galvanized coatings include:
(1) increase the coating thickness.
(2) alloying to obtain a zinc-ferroalloy coating, which is significantly more corrosion resistant than pure zinc-plating, and the alloy forging layer with a thickness of 7um is equivalent to 10:m thick pure zinc-plating layer .
(3) improve the zinc liquid ingredients, in addition to the 70-80 - s of the 20th century the development and commercialization of zinc - 5% A1 alloy plating (Galfan), people also developed a high corrosion resistance of zinc alloy galvanized layer of coating and special properties, such as 55% 55% zinc Al - 43.5% - Si alloy plating (Galvalume), 7 n Al - 6% - 6% Mg alloy gold sovereigns layer , zinc - Ni alloy plating agent: 33 and zinc magnesium alloyThe corrosion resistance ratio has been developed by using zn solution formulation.Traditional coating high 18 times of high corrosion resistant coating, and has been put into industrial production ,
(4) using two step hot dip method, the first key pure zinc, second zinc plated a1-6-0.5 Mg - 0.1 - Si alloy, can further improve the corrosion resistance , including alloying, also called diffusion annealing treatment, coating development earlier. After the alloying treatment, not only the corrosion resistance of the coatings increased, but also the welding performance and coating performance were greatly improved, so a large number of applications in wang automobile, household appliances and other fields. Galvalume products have developed rapidly in recent years, with higher corrosion resistance and beautiful surface, which are 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 dilute and soil are still an important research direction.