| 摘要 |
PURPOSE:To obtain an ultra-high pressure sintered material for cutting tools which has an intermediate layer consisting of TiB2 and has high toughness and strength, by compounding respective powders of cubic boron nitride, hyper-fine TiC and fine intermetallic compd. and subjecting the powder mixture to press molding, presintering and ultra-high pressure sintering. CONSTITUTION:The respective powders of the cubic boron nitride (CBN) having <=10mu average grain size, the hyper-fine TiC sized <=0.2mu, and the intermetallic compd. of CoAl, NiAl, etc., sized >=0.3mu and finer than CBN or TiCN sized <=1mu are compounded and the powder mixture is subjected to press molding. The molding is presintered in a 1,200-1,400 deg.C and 5-60min range in >=10<-2>Torr vacuum to form TiB2 which is the intermediate layer; thereafter, the molding is subjected to the ultra-high-pressure sintering. The sintered body which consists of 1-20% TiC of the bond phase, 1-10% intermetallic compd., and the dispersion phase CBN and the intermediate phase TiB2 (CBN is 70-95%) and of which the measurement result by X-ray diffraction satisfies the equation I is thereby obtd. This sintered body has the contact frequency satisfying the equation II when the number of contact between the CBN particles is designated as NC and the number of the contact of the CBN with the bond phase as Nb.
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