Fabrication of zinc coatings on alumina balls from zinc powder by mechanical coating technique and the process analysis

Abstract

Abstract Mechanical coating technique was used to fabricate zinc (Zn) coatings on alumina (Al 2 O 3 ) balls. The detailed evolution of the coatings was examined. The effect of the rotation speed of planetary ball mill on the evolution was investigated by experiments and modeling. The results showed that continuous and high dense Zn coatings with the average thickness of about 100 μm were formed during the milling operation at 300 rpm. To form continuous Zn coatings, a critical collision pressure corresponding to a critical minimum rotation speed was necessary to produce a critical plastic strain of Zn particles. Exponential relations between the required time to form continuous Zn coatings and the collision strength or the collision power were established. The relations showed that the required time was determined by the collision stress or the work done on Zn particles on unit area in unit time. The evolution of the coatings can fall into nucleation, formation and coalescence of discrete islands, formation and thickening of continuous coatings, and exfoliation of continuous coatings.