| 摘要 |
A surface-coated cermet cutting tool with a hard-coating layer having excellent chipping resistance, in which the hard coating layer formed on a surface of a tool substrate that constitutes the surface-coated cermet cutting tool is composed of the following upper and lower layers (a) and (b): (a) as the lower layer, a titanium compound layer having at least one or two of a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, a titanium carboxide layer and a titanium oxycarbonitride layer, all of which are deposited by chemical vapor deposition, the titanium compound layer having a total average layer thickness of 3 to 20 µm, and (b) as the upper layer, a heat-transformed ±-type Al-Zr oxide layer formed by carrying out a heat-transforming treatment in a state that a titanium oxide layer satisfying the composition formula: TiO Y , (where value Y is 1.2 to 1.9 in an atomic ratio to Ti when measured by Auger Electron Spectroscopy) and having an average layer thickness of 0.05 to 1.5 µm is chemically deposited on a surface of an Al-Zr oxide layer having a º-type or ¸-type crystal structure deposited by chemical vapor deposition and satisfying the composition formula: (Al 1-X Zr X ) 2 O 3 (where value X is 0.003 to 0.05 in an atomic ratio when measured by an electron probe micro-analyzer (EPMA)) to thereby transform the crystal structure of the Al-Zr oxide layer having the º-type or ¸-type crystal structure into an ±-type crystal structure. The heat-transformed ±-type Al-Zr oxide layer shows an inclination angle frequency-distribution graph on which a highest peak appears in an inclination angle interval in a range of 0 to 10 degrees and the sum of frequencies in a range of 0 to 10 degrees occupies 45% or more of the total sum of frequencies on the inclination angle frequency-distribution graph, in which the inclination angle frequency-distribution graph is obtained from the results of radiating electron beam onto crystal grains having a hexagonal crystal lattice in a measuring range of surfaces to be polished using a field-emission-type scanning electron microscope, measuring an inclination angle of a normal line of the plane (0001) as a crystal plane in which each of the crystal grains is formed with respect to each of the polished surfaces, sorting the measured inclination angles in a range of 0 to 45 degrees among all the measured inclination angles into several intervals at a pitch of 0.25 degrees, and summing up the frequencies in each of the intervals. The heat-transformed ±-type Al-Zr oxide layer has an average layer thickness of 1 to 15 µm. |
