A novel lapping process for single-crystal sapphire using hybrid nanoparticle suspensions

Abstract

Single-crystal sapphire is an important material with increasingly more widespread applications in optics, semiconductor and laser-related devices. However, its high hardness and brittleness have posed significant challenges for the efficient machining of sapphire with a satisfactory surface integrity. In this work, a new lapping process was developed for sapphire using a novel suspension that was made by dimensionally integrating alumina (Al2O3) nanoparticles with graphene oxide (GO) nanosheets in pure water. The performance of the Al2O3/GO hybrid nanosuspensions in the lapping of sapphire was systematically investigated using commercial diamond suspensions as the benchmarks. The multidisciplinary science involved in the new lapping process was unveiled. The use of the hybrid nanosuspensions during lapping enabled the generation of an oxide layer on the sapphire surface that was softer than its pristine substrate. This process thus simultaneously improved the removal efficiency and enhanced the surface quality, in comparison to conventional lapping.