Tool made of cubic boron nitride sintered body

Abstract

A tool includes a cubic boron nitride sintered body at least at a tool working point. The cubic boron nitride sintered body contains cubic boron nitride, a heat insulating phase, and a binder phase. Cubic boron nitride is contained in the cubic boron nitride sintered body by not less than 60 volume % and not more than 99 volume %, and the heat insulating phase includes one or more types of first compound composed of one or more types of element selected from the group consisting of Al, Si, Ti, and Zr and one or more types of element selected from the group consisting of N, C, O, and B. The first compound is contained in the cubic boron nitride sintered body by not less than 1 mass % and not more than 20 mass % and it has an average particle size smaller than 100 nm.

What is claimed is: 
     
         1 . A tool made of a cubic boron nitride sintered body, comprising a cubic boron nitride sintered body at least at a tool working point,
 said cubic boron nitride sintered body containing cubic boron nitride, a heat insulating phase, and a binder phase,   said cubic boron nitride being contained in said cubic boron nitride sintered body by not less than 60 volume % and not more than 99 volume %,   said heat insulating phase containing one or more types of first compound composed of one or more types of element selected from the group consisting of Al, Si, Ti, and Zr and one or more types of element selected from the group consisting of N, C, O, and B,   said first compound being contained in said cubic boron nitride sintered body by not less than 1 mass % and not more than 20 mass % and having an average particle size smaller than 100 nm, and   said cubic boron nitride sintered body having thermal conductivity not higher than 70 W/m·K.   
     
     
         2 . The tool made of a cubic boron nitride sintered body according to  claim 1 , wherein
 said first compound has an average particle size smaller than 50 nm.   
     
     
         3 . The tool made of a cubic boron nitride sintered body according to  claim 1 , wherein
 said heat insulating phase contains as its part, an unsintered region by not less than 0.01 volume % and not more than 3 volume % with respect to said cubic boron nitride sintered body.   
     
     
         4 . The tool made of a cubic boron nitride sintered body according to  claim 1 , wherein
 said first compound is a compound in which a solid solution of any one or both of oxygen and boron is present by not less than 0.1 mass % and not more than 10 mass % with respect to a nitride, a carbide, and a carbonitride of one or more types of element selected from the group consisting of Al, Si, Ti, and Zr.   
     
     
         5 . The tool made of a cubic boron nitride sintered body according to  claim 1 , wherein
 said heat insulating phase contains one or more types of second compound composed of W and/or Re and one or more types of element selected from the group consisting of N, C, O, and B, in addition to said first compound, and   said second compound is contained in said cubic boron nitride sintered body by not less than 0.1 mass % and not more than 2 mass %.   
     
     
         6 . The tool made of a cubic boron nitride sintered body according to  claim 1 , wherein
 said cubic boron nitride is contained in said cubic boron nitride sintered body by not less than 75 volume % and not more than 92 volume %.   
     
     
         7 . The tool made of a cubic boron nitride sintered body according to  claim 1 , wherein
 said cubic boron nitride is contained in said cubic boron nitride sintered body by not less than 80 volume % and not more than 87 volume %.   
     
     
         8 . The tool made of a cubic boron nitride sintered body according to  claim 1 , wherein
 said cubic boron nitride is composed of cubic boron nitride particles having an average particle size not greater than 1 μm.   
     
     
         9 . The tool made of a cubic boron nitride sintered body according to  claim 1 , wherein
 said cubic boron nitride sintered body has thermal conductivity not higher than 60 W/m·K.   
     
     
         10 . The tool made of a cubic boron nitride sintered body according to  claim 1 , wherein
 said tool working point has surface roughness Rz not less than 1 μm and not more than 20 μm.   
     
     
         11 . The tool made of a cubic boron nitride sintered body according to  claim 1 , wherein
 said cubic boron nitride sintered body has a minimum thickness not smaller than 2 mm at said tool working point.   
     
     
         12 . The tool made of a cubic boron nitride sintered body according to  claim 1 , wherein
 said cubic boron nitride sintered body and a tool shank portion are fixed to each other with a vibration-isolating heat-resistant plate being interposed, and   said vibration-isolating heat-resistant plate is made of an oxide, has thermal conductivity not higher than 40 W/m·K, and has a thickness not smaller than 0.3 mm.   
     
     
         13 . The tool made of a cubic boron nitride sintered body according to  claim 12 , wherein
 said cubic boron nitride sintered body and said tool shank portion are fixed to each other by screwing and/or self-gripping.