Hot dip metal coatings on steel or other substrate - using wiping chamber fed with hot redn. gas to obtain thin uniform coating

摘要

Process for the continuous wiping of a metal object, e.g. wire, strip or a grid, made of steel and travelling at a constant speed through a bath of molten metal to form a coating; the object then passes up a wiping chamber filled with a compact mass of inert granular material and fed with a redn. gas which also travels upwards. The novelty is that the gas is obtd. by the incomplete combustion of a hydrocarbon in air or O2, the gas being above 400 degrees C. when it is fed into the granular material. The pref. metal coating is zinc, and the pref. temp. of the redn. gas 400-650 degrees C. obtd. by the incomplete combustion of propane in air and delivered at 0.5-5 bars. The efficient wiping results in a thin but uniform coating of Zn when a substrate wire is travelling at 110 metres/minute, i.e. faster than in conventional processes.