Mitsubishi Materials Corporation

Kohei Tomita

Akira Osada

Eiji Nakamura

Makoto Igarashi

Sho Tatsuoka

A surface-coated cutting tool with a hard coating layer exhibiting an excellent flaking and chipping resistance in a high-speed heavy and intermittent cutting is provided. The vapor-deposited hard coating layer has a lower layer (Ti compound layer) and an upper layer (&#x3b1;-type AlOlayer). Thirty to 70% of AlOcrystal grains directly above the lower layer are oriented to (11-20) plane. Forty-five % or more of all of the AlOcrystal grains are oriented to (0001) plane. Preferably, the outermost surface layer of the lower layer is an oxygen-containing TiCN layer having oxygen content of 0.5 to 3 atomic % only within the depth region of 500 nm. The ratio of the number of AlOcrystal grains directly above the outermost surface layer to the number of crystal grains of the Ti carbonitride layer in the outermost surface layer is 0.01 to 0.5 in the interface.

Surface-coated cutting tool

A surface-coated cutting tool, which has a hard-coating layer with excellent chipping and fracturing resistances in a high speed intermittent cutting work, is provided. The surface-coated cutting tool includes a cutting tool body, which is made of WC cemented carbide or TiCN-based cermet, and a hard-coating layer, which is vapor deposited on the cutting tool body and has a lower layer and an upper layer. The lower layer is a Ti compound layer, and the upper layer is an aluminum oxide layer. There is a micropore-rich layer in the lower layer in the vicinity of the interface between the lower and upper layers. There are micropores with diameters of 2 to 70 nm in the micropore-rich layer. The diameters of the micropores in the micropore-rich layer shows a bimodal distribution pattern.

Surface-coated cutting tool having hard-coating layer with excellent chipping resistance and fracturing resistance

A surface-coated cutting tool includes a tool substrate made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet; and a hard coating layer formed by vapor-depositing in order, a lower layer (a), an intermediate layer (b), and an upper layer (c) on the tool substrate. The lower layer (a) is a Ti layer composed of one or more of a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, a titanium carboxide layer, and a titanium oxycarbonitride layer, and having a thickness of 3 to 20 &#x3bc;m. The intermediate layer (b) is an aluminum oxide layer having a thickness of 1 to 5 &#x3bc;m, and having an &#x3b1;-type crystal structure in a chemically vapor-deposited state. The upper layer (c) is an aluminum oxide layer having a thickness of 2 to 15 &#x3bc;m, and containing one or more elements of Ti, Y, Zr, Cr, and B.

Provided is a surface coated cutting tool in which a hard coating layer exhibits excellent chipping resistance in high-speed intermittent cutting processes. In the surface coated cutting tool having the hard coating layer including a lower layer (Ti compound layer) and an upper layer (AlOlayer) formed by vapor-deposition on the surface of the cutting tool body constituted by a WC-based cemented carbide or TiCN-based cermet, the ratio b/a of the number a of crystal grains in the Ti compound layer present in the interface to which the lower layer and the upper layer are adjacent to the number b of crystal grains in the AlOlayer is 4&#x2266;b/a&#x2266;20, and, furthermore, the average grain diameter of crystal grains in the Ti compound layer immediately below the AlOlayer is 0.5 &#x3bc;m or less.

Growing community of inventors

Joso, Japan

Kohei Tomita