高密着性α-Al_2O_3膜被覆切削工具の開発 [in Japanese] Development of High Adhesive α-Al_2O_3 Films Coated on Cemented Carbide Cutting Tools by CVD [in Japanese]
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Cemented carbide cutting tools coated with a TiN layer, a MT-Ti(C, N) layer, a bonding layer and a α-A1<SUB>2</SUB>O<SUB>3</SUB> layer in subsequent process steps in a hot wall Chemical Vapor Deposition (CVD) reactor have been developed, whose lifetime was about twice as long as that of the ordinary K-A1<SUB>2</SUB>O<SUB>3</SUB> coated ones in cutting tests on a cast metal FC250 due to the improved adherence of α-A1<SUB>2</SUB>O<SUB>3</SUB> layer.<BR>The CVD coatings of the developed cutting tools have been investigated using X-ray diffraction, SEM, EPMA, TEM and TEM-EDX, and the following characterisTiCs were found:<BR>(1) The bonding layer grains consisted of Ti, C, N and O, or of Ti, C and O.<BR>(2) The crystal structure of the bonding layer phase were found to be face centered cubic with the latTiCe parameter of 0.431 nm.<BR>(3) The bonding layer grains grew epitaxially on the MT-Ti(C, N) layer grains.<BR>(4) No disorder of latTiCe fringes in some interfaces between the bonding layer grains and the α-Al<SUB>2</SUB>O<SUB>3</SUB> layer grains could be found.<BR>The facts (3) and (4) among these were considered to be the causes for the improved lifetime or adherence of the α-Al<SUB>2</SUB>O<SUB>3</SUB> layer.
- J. Jpn. Soc. Powder Powder Metallurgy
J. Jpn. Soc. Powder Powder Metallurgy 45(6), 561-565, 1998-06-15
Japan Society of Powder and Powder Metallurgy