Development of Hot-dip Zinc Coating Process Using Under Layers

摘要

Zinc coated steel sheets have been widely used for automobiles, household electric appliances and building, based on their high corrosion and superior function. Hot-dip galvanization is the oldest and economical method used for applying zinc based coating on steel. Many reports are available on influence of alloying elements on the performance of the coating. Recently, there are few investigations regarding the deposition of under layers and the incorporation of oxide particles with zinc metal to enhance the structure, performance and the lifetime of galvanized steel sheet. A new coating system of under layer of hot dip zinc coating was explored as an effective coating for steel especially for application in relatively high aggressive environments. The deposition of under layers enhances the structure, performance and the lifetime of galvanized steel sheet. The effect of different barrier layers formed prior to hot dip galvanization was investigated. The coating morphology was characterized by scanning electron microscope (SEM) analysis. The hot dip zinc coatings containing under layer showed substantial improvement in their properties such as good adhesion, less porosity, and high hardness. In addition, it decreases the thickness of the coating layer and enhances the corrosion resistance.