Influence of grinding parameters on strength-dominating near-surface characteristics of silicon nitride ceramics

The complex relationship between machining parameters, surface quality and strength of sintered silicon nitride (SSN) was investigated using roughness measurements, SEM observations, strength tests and X-ray diffraction techniques. Conventional grinding as well as creep-feed grinding, high-speed grinding and grinding at high material removal rates have been studied. From the results detailed information is derived about the effect of different grinding parameters on near-surface effects and on strength. The results demonstrate the limitations of often proposed correlations between strength and other 'characteristics' of machined surfaces, like roughness values or theoretically derived values of the chip thickness. Guidelines for optimized grinding parameters are established.