On the mechanism of material removal by fixed abrasive lapping of various glass substrates

Glass ceramics are one of the important materials for optoelectronic devices. Fixed abrasive, double-sided lapping parameters (time, pressure, and platen speed) were optimized using borofloat, BK7 and quartz substrates. Lapping of borofloat, BK7 and quartz substrates were performed at optimized conditions. The removal rate was found to be highest in the case of borofloat, followed by quartz and BK7. The removal rate trend could not be explained based on the hardness of the material because quartz shows higher removal rate in spite of its higher hardness when compared to the BK7 substrate. The glass substrate forms a hydrated layer when it is exposed to an aqueous environment, and that depends on the composition of the substrate. The hardness of the material decreases significantly in the aqueous environment due to the formation of a hydration layer. The formation of a hydration layer is thought to facilitate faster and easier penetration of diamond abrasive into the substrate. Penetration then results in brittle fracture and the formation of lumps of debris.