Microscopic characterization of machined high-performance ceramics using acoustical, optical and mechanical NDT

Ground surfaces of alumina (Al203), silicon infiltrated silicon carbide (SiSiC) and pressureless sintered silicon carbide (SSiC) have been investigated nondestructively by employing Scanning Acoustic Microscopy (SAM), Atomic Force Microscopy (AFM) and Confocal Scanning Laser Microscopy (CSLM). Subsurface microcrack densities, evaluated by SAM images, were correlated with grinding parameters such as abrasive grain size and grinding speed. Furthermore, microcrack densities were found to be decreased after tribological tests. The surface topography of machined surfaces was measured on a sub-micrometerscale with the AFM. The AFM images distinguished between different phases in multiphase ceramics. CSLM images of Al203 samples provided information about the sample microstructure and material removal meachnism by grinding.