粉体および粉末冶金
Online ISSN : 1880-9014
Print ISSN : 0532-8799
ISSN-L : 0532-8799
α-Al2O3被覆工具の高密着性化機構の研究
石井 敏夫島 順彦植田 広志権田 正幸岡山 史郎
著者情報
ジャーナル オープンアクセス

2000 年 47 巻 2 号 p. 121-125

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抄録
Microstructure of α-Al2O3-coated turning inserts whose tool lives were longer than K-Al2O3-coated ones have been investigated. These inserts were coated successively with a TiN layer, a MT(moderate temperature)-Ti(C, N)layer, a bonding layer, and a α-Al2O3 layer on cemented carbide inserts by using chemical vapor deposition(CVD). X-ray diffraction, SEM and TEM were used to characterize the coatings, and following characteristics were found.
(1) Epitaxial growth was observed in a column of MT-Ti(C, N) twinned grains, bonding layer twinned grains and α-Al2O3 grains by cross-section TEM, where(100)-planes of the α-Al2O3 grains were parallel with(110)-planes of both the MT-Ti(C, N)grains and the bonding layer grains, and(003)lattice fringes of the α-Al2O3 grains continue almost linearly from {111} lattice fringes of the bonding layer grains.
(2) (120)-planes of the α-Al2O3 grains and (211)-planes of both the MT-Ti(C, N)grains and the bonding layer grains in the column were parallel to the substrate, too.
(3) Many steps at the surface of vertical-plane-shape protrusions formed along the twin boundaries on the surface of the bonding layer, might promote the epitaxial growth of α-Al2O3 grains on the bonding. layer.
(4) The above mentioned microstructure agrees with X-ray diffraction results on the MT-Ti(C, N) layer and the α-Al2O3 layer. This may mean that the epitaxial growth will be found in many columns in the α-Al2O3-coated turning inserts.
The above mentioned epitaxial growth and the protrusions between the bonding layer grains and the α-Al2O3 grains are considered to be the cause for improved α-Al2O3 layer adherence and longer tool life.
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