METHOD OF PREVENTING DEFECTS IN ALUMINIUM-ZINC ALLOY COATINGS OBTAINED BY A HOT-DIP PROCESS, AND APPARATUS THEREFOR

摘要

The occurrence of defects on wire coated with an aluminum-zinc alloy coating applied by hot dipping in a molten coating bath is substantially decreased by preventing the deposition of zinc powder particles upon the surface of the molten aluminum-zinc coating prior to solidification of the coating. The deposition of metallic zinc powder particles upon the molten aluminum-zinc coating may be alleviated in several different manners, including preventing the formation of the zinc powder, preventing the accumulation of the zinc powder upon the surface of the molten aluminum-zinc bath, decomposing the zinc powder before it accumulates and exhausting or removing the zinc powder from the vicinity of the molten metal coated wire as it leaves the molten bath. Several novel apparatus arrangements for accomplishing the above are disclosed.