Dual strobe and single strobe once per revolution imaging techniques are employed on the Rapidly Renewable Lap (RRL) to study the ductile to brittle transition observed during the polishing of silicon and calcium flouride. Analysis of video images during polishing, optical microscopy of the lapped surfaces and scanning electron microscopy (SEM) of the lapping film after polishing suggest the observed step increase in material removal rate with diamond size is due to an increase beyond the critical grit penetration depth necessary for crack inititation, the ductile to brittle transition commonly observed in ceramic and glass materials. A model derived for lateral crack extension in ceramics is applied to the brittle material removal regime here and found to agree with the experimental data. An explanation for apparent shifts in the ductile to brittle transition during lapping of ductile materials using lapping films of various compliances is also discussed.
Citation: Transactions of North American Manufacturing Research Institute Journal of Manufacturing Science and Engineering
Pub Type: Journals
brittle, ductile, fracture, lapping, material removel, polishing