The Investigation of Effects of Galvanizing Parameters on Microstructure of Al-Zn-Si Coating

In this article, the effects of galvanizing process parameters, especially cooling rate, on the microstructures of coating was investigated. The microstructures of Al-Zn-Si coating were analyzed by the following methods: surface microstructure, cross-section microstructure, thickness and composition of alloy layer by SEM and its accessories, distribution of each element along depth by glow-discharge emission spectrometer, micro-area elemental distribution image analysis of each element distribution on surface and cross-section by electron probe, crystallization orientation by X-ray diffraction instrument. The results showed that coating was made up of aluminum-rich dendrite, interdendritic zinc-rich phase and alloy layer, that cooling rate affected depth of alloy layer in Al-Zn-Si coating directly, that zinc concentrated in the surface layer of coating and silicon in the alloy layer, while the coating has larger depth it also concentrated in the surface layer, that aluminum-rich dendrite has preferred orientation in the solidification process.