Analysis of oxide defect formation on GI. exposed outer body automotive panels during continuous hot dip galvanizing

摘要

With increased demand for GI outer panel material for the automotive sector, continuous improvement of zinc coating quality is required. Various surface defects arise from poorly understood and uncontrolled snout practices during coating on a CGL. One such defect produced within the ZODIAC snout, the arrowhead defect, has been characterised with use of SEM/EDX and XRD and compared with contamination collected from the ZODIAC snout. The presence of ZnO, originating from the injection of wet HNx into the snout as a method to reduce the formation of zinc vapour, was observed in regions consistent with the head end of the arrowhead defect. Discrete intermetallic dross particles were entrained within the tail of the defect. XRD patterns of both the defect & snout contamination have been presented to discern the nature of the contamination entrained within the zinc coating.