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US 4,412,980 AGranted
Method for producing a diamond sintered compact
AssigneeSumitomo Electric Industries, Ltd.
InventorsKazuo Tsuji, Shuji Yazu, Akio Hara
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AssigneeSumitomo Electric Industries, Ltd.
InventorsKazuo Tsuji, Shuji Yazu, Akio Hara
Estimating the term…
The invention relates to a diamond sintered compact wherein diamond crystal particles are uniformly oriented in a particular direction and the method for producing the same, and has for an object to provide a diamond sintered compact having a high thermal conductivity particularly suitable for heat sink for use in the field of electronics. According to the invention, graphite is used as carbonaceous raw material, diamond crystal particles having such elongated shape that the ratio of the length of the long axis to that of the short axis is more than 2 being synthesized in such state that the greater part of the crystal particles have their long axes uniformly oriented in a particular direction, the crystal particles being sintered in the direction of the long axes thereof so that transformation of the graphite into diamond and sintering thereof may be accomplished synchronously. The invention has for an object to obtain a diamond sintered compact suitable for the aforesaid use by degassing reaction system raw material plugged into an air permeable container by heating it in vacuum in order to intercept gaseous components causing a decrease of thermal conductivity at the time of synthesizing diamond from carbonaceous material and a catalytic metal and sintering thereof, subsequently the air permeable part of the said container being sealed by means of soldering material preliminarily placed in contact with the said container.
A method for producing a diamond sintered compact having diamond crystal particles uniformly oriented in a particular direction, which comprises placing a carbonaceous material as a raw material for producing diamond, and a catalytic metal for crystallizing diamond, in layered or concentric relationship to each other the catalytic metal comprising between 5 to 50 weight % of the total weight of the carbonaceous material and catalytic metal, a metal inert to synthesis of diamond or a metal having a higher melting point than the catalytic metal being interposed at the interface between the carbonaceous material and catalytic metal, subjecting the resultant assembly to temperature and pressure under conditions of a pressure higher than 65 kb, and a temperature higher by 200.degree. C. than the eutectic temperature of the catalytic metal and carbon and lower by 100.degree. C. than the thermodynamic equilibrium line of diamond versus graphite, the rate of temperature rise beyond the eutectic temperature being at least 100.degree. C./min. predetermined pressure and temperature conditions within these limits being maintained for a time sufficient for formation and growth of diamond crystals and sintering of each diamond particle, thereby enabling synchronous transformation of the carbonaceous material into diamond and sintering of the diamond.
Dependencies are inferred from the claim text.