| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a silicon nitride-based ceramic material for a metal cutting tool which has a composition suitable for machining a metal or a heat resistant super alloy and has good boundary wear, acceptable flank wear and sufficient toughness. <P>SOLUTION: The ceramic material comprises β-sialon (Si<SB>6-Z</SB>Al<SB>Z</SB>O<SB>Z</SB>N<SB>8-Z</SB>), a phase of crystal polytype 12H, and a grain boundary amorphous or partly crystalline phase, and contains yttrium. in which the amount of grain boundary phase measured as the area attributable to this phase relative to the total area of a SEM (scanning electron microscope) picture is between 5 and 15%, the z-value is 0.7-<1.5, the amount of the phase pf crystal polytype 12H measured as the ratio of the peak height in an X-ray diffractogram of the CuKα peak at a 2θ value of 34° and the peak height in the same diffractogram of the peak from β-sialon at a 2θ value of 33° is between 2 and 20% and the content of yttrium is 3.5-5 wt-%, preferably 3.9-4.5 wt-%. <P>COPYRIGHT: (C)2008,JPO&INPIT |
