The Surface Layer of Fused Silica Finished by Various Polishing Techniques

Our recent experiments show that the surface layer of fused silica manufactured by the magnetorheological finishing(MRF) is different from those finished by conventional polishing technique (e.g. pitch polishing or polyurethane polishing) in mechanical properties. We examined the hardness of the surface layer on fused silica polished by pitch/pad polishing and MRF respectively, and the results indicate that the hardness of traditionally polished layer is smaller than bulk material, decreasing with the distance from the sample surface, while the nanohardness of MRF-manufactured sample is greater than bulk, gradually increasing to the bulk value. We attribute the differences to the unique material removal mechanism of MRF. The distinctions among these polishing techniques may make contribution to varied laser-induced breakdown topography.