12. What is zinc-aluminum alloy block? Why is it used in hot-dip galvanizing?

Zinc-aluminum alloy is formed by casting thin blocks through the eutectic fusion of pure zinc and pure aluminum. In hot-dip galvanizing production, where the zinc bath temperature ranges from 470-510°C while aluminum's melting point reaches 660°C, adding pure aluminum becomes technically challenging. However, the eutectic phase diagram reveals that when aluminum constitutes approximately 7% and zinc 93%, the resulting eutectic temperature drops to around 380°C. This optimized composition enables zinc bath to easily dissolve the alloy blocks, making it significantly easier to incorporate the required aluminum into the zinc bath through this method.In actual production, in order to facilitate the calculation of aluminum content in zinc liquid, there are also zinc-aluminum alloy blocks made of 10% pure aluminum and 90% pure zinc.