ASSESSMENT OF TECHNIQUES FOR CHARACTERIZING THE SURFACE QUALITY OF GROUND SILICON-NITRIDE

This study evaluates techniques used to detect and quantify the extent of surface and subsurface damage in ground silicon nitride, Specimens of two differently ground surfaces of a hot isostatically pressed (HI P) silicon nitride, commercially designated as GS-44, were subjected t o six types of analyses, namely mechanical stylus profiling, atomic fo rce microscopy, point-counting analysis of fragmentation pits, laser-l ight scattering, optical gating, and grazing incidence x-ray diffracti on (GIXD), The results of these investigations are compared and discus sed. The techniques providing the dearest correlations with grinding c onditions were mechanical stylus roughness, fragmentation analysis, an d GIXD (residual stress conditions). Those that exhibited some correla tion but appear to require more work to develop a reliable evaluation method were laser scattering and optical gating, Atomic force microsco py was useful, but not as a routine investigative tool for quality con trol in ceramic machining. The techniques that appear to have the most near-term potential for routine use are fragmentation analysis and op tical gating, Laser-based optical scattering exhibits potential for ro utine application, but, more development is needed for its commerciali zation.