Abstract: A coated cBN sintered body tool has improved wear resistance and fracture resistance. The coated cBN sintered body tool has a substrate of a cBN sintered body and a coating layer coated on the surface thereof. The cBN sintered body includes 73 to 84% by volume of cBN and 16 to 27% by volume of a binder phase and inevitable impurities. An average grain size of the cBN is 1.5 to 4.0 ?m; an average value of the thickness of the binder phase is 0.05 to 0.5 ?m; and a standard deviation of the thickness of the binder phase is 0.5 ?m or less. The coating layer includes an upper layer of Ti(CxN(1?x)), an intermediate layer including a metal, a lower layer including an alternately laminated layer of (Ti(1?y)Siy)N thin layers and (Al(1?z)Crz)N thin layers, and an undermost layer of (Al(1?a)Cra)N.

Abstract: A cBN sintered body tool has a cBN sintered body which includes 40 to 85% by volume of cBN, the remainder being a binder phase including at least one selected from at least one metal selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Co, Ni and Al, and at least one of a carbide, a nitride, a carbonitride, a boride and an oxide of these metals and mutual solid solutions thereof, and inevitable impurities. An amount of a Mo element contained in the cBN sintered body is 0.2 to 3.0% by weight based on a whole amount of the cBN sintered body.

Abstract: A coated cBN sintered body tool has improved wear resistance and fracture resistance. The coated cBN sintered body tool has a substrate of a cBN sintered body and a coating layer coated on the surface thereof. The cBN sintered body includes 73 to 84% by volume of cBN and 16 to 27% by volume of a binder phase and inevitable impurities. An average grain size of the cBN is 1.5 to 4.0 ?m; an average value of the thickness of the binder phase is 0.05 to 0.5 ?m; and a standard deviation of the thickness of the binder phase is 0.5 ?m or less. The coating layer includes an upper layer of Ti(CxN(1-x)), an intermediate layer including a metal, a lower layer including an alternately laminated layer of (Ti(1-y)Siy)N thin layers and (Al(1-z)Crz)N thin layers, and an undermost layer of (Al(1-a)Cra)N.