The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings. The drawings are not to scale, and are given by way of illustration only. Accordingly, the drawings should not be construed as limiting the present invention.
Conventional processing, illustrated in
Processing in accordance with the present invention is illustrated in
This invention provides a process for increasing the density of carbon-carbon composite part. The method of this invention may include several consecutive steps, as follows. Step (a.) is providing the carbon-carbon composite parts, e.g. aircraft brake disc preforms. In step (b.), the carbon-carbon composite parts are subjected to chemical vapor deposition in a CVD furnace, e.g. at a temperature in the range 1000-2000° C. Step (c.) involves forcing cooling air (typically, air at ambient temperature) through the CVD furnace, where it absorbs heat and becomes warmed air. In step (d.) of the present invention, this warmed air is then passed through a tar trap, e.g. at a rate of 5000 feet per second, where its content of soot and/or tar is reduced. Step (e.) is cooling the purified, warmed air. This is typically passive cooling, by conduction through the walls of equipment employed to channel the cooling air. Steps (c.)-(e.) are then repeated continuously, for instance over a period of about 24 hours. Finally, the resulting densified carbon-carbon composite parts are removed from the CVD furnace.
The following tables illustrate CVD cooling cycle time improvements provided by the present invention.
The present invention has been described herein in terms of preferred embodiments. However, obvious modifications and additions to the invention will become apparent to those skilled in the relevant arts upon a reading and understanding of the foregoing description. It is intended that all such modifications and additions form a part of the present invention to the extent that they fall within the scope of the several claims appended hereto.