| 摘要 |
PURPOSE:To raise stiffness of a tool with small diameter by jointing a hard sintered substance including more than 60vol% of high pressure phase type boron nitride having smaller volume than the supporting member at the tip of a rod- shaped supporting member. CONSTITUTION:A super hard alloy obtained by bonding a carbide of the 4a-6a group elements in the periodic table with a ferric metal, for example, tungsten carbide bonded with 5-15% cobalt, is formed into a bar to have a supporting member 2, and at its tip a hard sintered substance 1 including more than 60vol% of high pressure type boron nitride is jointed to subject to a sintering process. Volume ratio of this hard sintered substance 1 to the supporting member shall be normally 1:5, preferably >1:10. Interposition of an intermediate layer with comparatively small content of cubic crystal boron nitride between the hard sintered substance 1a and supporting member 2 will contribute to prevention of enbrittlement of the joint part. |
