Design of Core-Shell Structured Diamond/Ceo2 Composite Abrasives for Ultra-Smooth and Efficient Polishing on Sapphire Wafers

Novel diamond/CeO 2 composite abrasives were successfully synthesized by a modified precipitation approach without explosive hazardous chemicals for ultra-smooth and high-efficiency polishing of sapphire wafers. The composite abrasives were well dispersed without agglomeration, the CeO 2 crystallites of cubic fluorite structure with a thickness of about 10 nm were tightly coated on the diamond surface employing chemical bonding, and their formation process was discussed in depth. Based on a semi-fixed polishing pad, the polishing performance of pure diamond and composite abrasives on sapphire wafers was evaluated. Experimental results showed that the surface roughness of the as-prepared composite abrasives was reduced by 26.5% bringing an almost scratch-free surface, accompanied by a 10.6% improvement in material removal rate, as well as a reduction in residual stress by about 29.8% with respect to pure diamond. Finally, the polishing mechanism and interfacial contact behavior of composite abrasives were investigated in depth through the analysis of polished sapphire surface and wear debris, combined with the theory of micro-contact mechanics. The improvement of polishing performance may be attributed to the mutual balance and promotion of chemical corrosion and mechanical action.