Dynamic behavior investigation of zinc vapor in the vacuum spray galvanizing process based on the direct simulation Monte Carlo method

Abstract

Continuous strip vacuum spray galvanizing is recognized as an innovative and environmentally friendly technique for producing high-purity, dense zinc coatings on steel strips. However, it is challenging to experimentally study the transport dynamics of zinc vapor in a low-pressure environment. To address this, the direct simulation Monte Carlo (DSMC) method was employed to analyze the effects of nozzle design and vacuum chamber pressure on zinc vapor dynamics behavior during the coating process. The results indicate that the mass flux distribution of the zinc vapor jet is uniform across the strip width, especially from the center to approximately 0.14 m on either side of the steel strip. Reducing the chamber pressure to 0.001 Pa enhances the uniformity of zinc vapor distribution near the nozzle by 8.4 %. Additionally, using round nozzles further improves coating thickness uniformity by 30 %, particularly at the strip edges. The calculated coating thickness aligns well with experimental data, with an average relative error of less than 2 % in the strip’s central region. This study provides a theoretical basis for optimizing process parameters and nozzle design in vacuum spray galvanizing.