Verschleissmechanismen von Siliziumnitridkeramik in Abhaengigkeit des Werkstoffes. Teilprojekt: Einfluss des Schneidstoffgefueges auf das Verschleissverhalten von Siliziumnitridkeramik im Zerspanprozess Abschlussbericht

The use of silicon nitride cutting tools is in fact of low reliability and high wear limited on special processes. The influence of cutting tool and workpiece structure on the wear behaviour was investigated. The important wear mechanism in milling of ductile cast iron are chemical reactions. Due to this fact a built-up edge is formated and covers the tool against further wear. The use of silicon nitride in machining steel is limited by the softening of a grain boundary phase which starts at about 900 C. In machining of grey cast iron silicon nitride achieve high tool life. Thermal load simulation by laser-beaming were carried out to investigate the role of these thermoshocks and to measure the resulting temperature distribution. In addition Finite-Element-calculations show the internal temporal temperature in these ceramic tool tips. Linear behaviour between cutting tool temperature and heat flow respectively simulation time was established. With regard to the material development the influence of dispersion of hard materials was investigated. In this connection the influence of cutting material composition and production was discussed. Coating of silicon nitride should be a possibility to expand the use of silicon nitride cutting tools. The results give hints for the use and for the development of Si_3N_4 cutting tools. (orig.)SIGLEAvailable from TIB Hannover: F95B288+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman