Process for coating carbon fiber reinforced carbon

Details Process for coating carbon fiber reinforced carbon Process for coating carbon fiber reinforced carbon

1994-09-09

1996-02-06

Bell, James J.

Chemistry of inorganic compounds

Carbon or compound thereof

Elemental carbon

29 8806, 29888061, 298897, 4234471, 4234472, 4272551, 4272552, 4272553, 4272557, 427575, 427579, 428408, 428902, D01F 912

Patent

active

054894220

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a process for coating carbon with an amorphous Sin.sub.x layer and a protective layer made of crystalline silicon nitride by means of CVD deposition.
From DATABASE WPIL, Section Ch, Week 4483, Derwent Publications Ltd., London, GB; Class CO4, AN-83-805055, C 44 & JP A-58161981, of Sep. 26, 1983, a process is known in which ceramic bodies are coated by means of CVD-coating with a first layer made of amorphous Sin.sub.x and another layer made of crystalline silicon nitride Si.sub.3 N.sub.4. Based on this state of the art, carbon fiber reinforced carbon is to be coated by means of the present invention.
Carbon fiber reinforced carbon is distinguished by a high strength while its endurance is very good. However, at this time, a wide use of this material is very limited because of the lacking oxidation stability. Particularly, a use above 400.degree. C. is hardly possible without any protective gas.
However, because of the above-mentioned strength characteristics and the low weight, as use particularly in air and space travel technology would be advantageous.
The present invention is therefore based on the problem of providing a process for coating carbon fiber reinforced carbon by means of at least one layer in such a manner that a high oxidation resistance is possible also at higher temperatures, thus above 400.degree. C., particularly also above 1,500.degree. C.
According to the invention, this problem is achieved in that an Sin.sub.x -layer is applied as the bonding layer by means of PECVD-deposition to the carbon fiber reinforced carbon (CFC), and the depositing of the protective layer takes place in a reaction space which was cleaned by means of an H.sub.2 /HCl gas mixture before the depositing, and the protective layer is deposited essentially while avoiding stable diimides.
Amorphous silicon nitride is deposited as the bonding layer in order to advantageously adapt the different coefficients of expansion of the carbon fiber reinforced carbon and of the protective layer to one another, since their coefficients of expansion have excessive deviations with respect to one another, so that otherwise there is the danger of crack formations or of a chipping-off of the protective layer. For depositing the bonding layer made of amorphous Sin.sub.x, a micro-multipolar plasma, such as DECR (Distributed Electron Cyclotron Resonance) plasma may be used.
Particularly, in order to insure that the protective layer will be free of cracks and cannot chip off, the application of the protective layer containing silicon nitride should take place while avoiding stable diimides or essentially avoiding stable diimides.
In order to ensure that stable diimides are not present when the silicon nitride layer is deposited, which stable diimides otherwise would also be deposited on the carbon fiber reinforced carbon and could therefore result in the formation of cracks of the protective layer, the used reaction space is cleaned in an H.sub.2 /HCl-gas mixture before the protective layer is deposited.
In this case, crystalline Si.sub.3 N.sub.4 may be applied as the protective layer. Amorphous Sin.sub.x or SiO.sub.2 or a combination of these with crystalline Si.sub.3 N.sub.4 may also advantageously be applied so that, by means of the process according to the invention, a carbon fiber reinforced carbon is made available which is resistant to oxidation also at high temperatures above 1,500.degree. C., even above 1,700.degree. C., and is therefore suitable to be used particularly in air and space travel technology. Consequently, components such as the outlet cone in the case of turbines, turbine casings, hot-gas guiding components, combustion chambers, guide blades or others, can be manufactured from the carbon fiber reinforced carbon improved according to the invention.
As a further development of the invention, it is provided that, the carbon fiber reinforced carbon is cleaned before the bonding layer is applied. This may take place by a bombardment by means of noble gas ions, such as argon ions of a plasma, pref

REFERENCES:
patent: 5254397 (1993-10-01), Kawai et al.
Deposition of Silicon Dioxide and Silicon Nitride by Remote Plasma Enhanced Chemical Vapor Deposition; G. Lucovsky, P. D. Richard, D. V. Tsu, S. Y. Lin and R. J. Markunas; Dept. of Physics, North Carolina State University; Journal of Vacuum Science & Technology, May-Jun. 1986; pp. 681-688.
Composition and Structure Control by Source Gas Radio in LPCVD SiN.sub.x ; Takahiro Makino; Nippon Telegraph and Telehone Public Corporation, Mushahino Electrical Communication Laboratory; Journal of Electrochemical Society, No. 2, Feb. 1983; pp. 450-455.

Affiliated with

Also associated with

Rating

Process for coating carbon fiber reinforced carbon does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for coating carbon fiber reinforced carbon, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for coating carbon fiber reinforced carbon will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2173869