DEVELOPMENT AND WEAR BEHAVIOR OF SILICON- NITRIDE CERAMIC

Cutting tools based on silicon nitride ceramic have been employed succ essfully in industrial ranges of application especially in cutting of grey cast iron. Nevertheless their availability is still limited due t o various reasons, depending on the specific material properties. In o rder to improve the wear behaviour and the reliability of these tools a new silicon nitride ceramic matrix, bonded with grains of carbides, was developed. The paper presents results obtained during investigatio ns on material specific wear mechanisms in face milling and turning. T he responsible wear mechanism in turning are the high tool temperature s. They leads to a softening of the grain boundary phase so that the S i3N4-grains can be removed by the chip now. The wear in milling is due to the high mechanical load accompanied with the frequency in period of cutting.