Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Patent
1992-07-10
1994-06-07
Turner, A. A.
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
428336, 428408, 428697, 428698, 428701, 428702, 51295, 51309, 501 97, C04B 4187
Patent
active
053188365
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a diamond-coated body and, more particularly, to a diamond-coated body which can extensively be employed for various cutting tools such as bites, end mills, cutters, drills and so on and abrasion resistant members.
BACKGROUND TECHNOLOGY
Heretofore, cutting tools, etc. are prepared by coating the surface of a ceramic substrate with a diamond film. However, such a diamond film is so insufficient in adhesion as their tips cause chipping.
More description will be made on this point. For instance, Japanese Patent Publication (kokoku) No. 59,086/1985, and Japanese Patent Laid-open (kokai) Publication Nos. 109,628/1986 and 291,493/1986 disclose technology which involves using a silicon nitride substrate or a ceramic substrate having a particular thermal expansion coefficient in order to provide a diamond-coated material having high adhesion.
These technology, however, each involves prevention of the diamond film from peeling off by suppressing the thermal stress generating upon cooling after the formation of the diamond film, yet its adhesion is not yet sufficient.
For instance, when chips with such a diamond film coated thereon are used for cutting, their tips may still cause chipping.
The object of the present invention is to provide a diamond-coated body which has so high in adhesion of its diamond film as to avoid chipping and which can be prepared with ease.
DISCLOSURE OF INVENTION
The diamond-coated body according to the present invention is characterized in that the diamond film is formed on the surface of the ceramic substrate in which acicular grains having a thickness of 0.2 .mu.m to 1 .mu.m and an aspect ratio of 2 or higher are contained at the two-dimensional density of 30% or higher.
BEST MODES FOR CARRYING OUT THE INVENTION
Ceramic Substrate
The ceramic substrate to be employed for the present invention contains acicular grains on its surface, whose thickness ranges from 0.2 .mu.m to 1 .mu.m and has an aspect ratio of 2 or higher, preferably 3 or higher, more preferably 4 or higher, at the two-dimensional density of 30% or higher, preferably 40% or higher.
It is noted herein that the thickness, the aspect ratio and the content of the acicular grains referred to herein can be determined by forming a mirror surface by polishing a surface of the substrate, etching the mirror surface with phosphoric acid to remove the intergranular interface around acicular grains, taking a picture of an etched surface of the substrate and analyzing the picture by image processing in two dimentions.
The two-dimensional density referred to herein is defined by a percentage of occupation area for the acicular grains in a given constant area in a surface of substrate. The occupation area is given by totalizing each area occupied by the acicular grain in the picture.
As the acicular grains are considered as existing in a random way, the thickness and the aspect ratio of the acicular grains referred to herein are the values which are given with particles lying horizontally or obliquely taken into account.
No theoretical elucidation is yet made on the reason for improvement in adhesion of the diamond film in accordance with the present invention, which is achieved by allowing the acicular grains having the thickness ranging from 0.2 .mu.m to 1 .mu.m and the aspect ratio of 2 or higher to exist at the two-dimensional density of 30% or higher. However, the present inventors presume that the surface of the ceramic substrate causes minute roughness in concave and convex ways by the acicular grains and that the intergranular interface of the ceramic substrate is etched with an atmospheric plasma gas of a CVD in the initial stage of formation of diamond, thereby causing the acicular grains to project and penetrate into the diamond film formed thereon as if an anchor and, as a result, increasing a contact area between the diamond film and the surface of the ceramic substrate to a remarkable extent and increasing a peeling strength of the diamond film.
If the thickness of th
REFERENCES:
patent: 4134947 (1979-01-01), Oda et al.
patent: 4578087 (1986-03-01), Tanaka et al.
patent: 4707384 (1987-11-01), Schachner et al.
patent: 4731296 (1988-03-01), Kikuchi et al.
patent: 4734339 (1988-03-01), Schachner et al.
patent: 4886767 (1989-12-01), Goto et al.
patent: 4990403 (1991-02-01), Ito
Popper "Sintering of Silicon Nitride, A Review" Progress in Nitrogen Ceramic edited by Riley 1983, pp. 187-210.
Farabaugh et al. "Growth of diamond films by hot filament chemical vapour deposition" SPIE vol 969, 1988 pp. 24-31.
Iio Satoshi
Ito Toshimichi
Tsubokawa Masaya
Watanabe Masakazu
Idemitsu Petrochemical Company Limited
NGK Spark Plug Company Limited
Turner A. A.
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