Micro-Hole Drilling on Silicon Nitride Ceramics in Ethanol

Abstract

Micro-hole drilling of engineering ceramics has potential for application to fuel injection nozzles and fiber spinning nozzles, etc. To date among engineering ceramics, less study has been reported on the micro-hole drilling of silicon nitride. We therefore conducted micro-hole drilling of hot-pressed silicon nitride using a chemical vapor deposition (CVD) diamond-coated tool with ethanol as the cutting fluid. As a result, the successful drilling of silicon nitride was achieved with a smooth drilled surface and sufficient accuracy of the hole size. Wear damage of the CVD coated diamond tool and drilling debris of silicon nitride were investigated using scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX). As a result, it is suggested that tribochemical reaction of silicon nitride effectively contributed to the micro-hole drilling characteristics; that is, smoother hole surface was obtained due to the polishing action of wear debris and tribochemical reaction products. The hole inlet size, varied during successive drilling process, could be explained in relation to the wear damage of the diamond-coated drill tip.