Quantitative analysis of top dross formation mechanism in metal coating baths

摘要

Simulation experiments were conducted to identify the dominant factors that affect top dross generation in metal coating baths. From the experiments and the mi-crostructural analyses of the top dross, it is proposed that top dross is generated through bath metal entrainment by the oxide film and subsequent drainage during holding. A new concept, taking into consideration the fresh area creation during the wiping process, is introduced and a mathematical model is developed to quantify dross generation in the metal coating process. From the proposed mechanism, a new metric is developed to quantify top dross generation in the coating bath. The experimental results agree well with both theoretical results and production data of galvanising (Gl) baths based on this metric.