1. Field of the Invention
The present invention relates to carbon--carbon composites, and more particularly to a method for joining carbon--carbon composites parts with minimum surface preparation.
2. Description of the Prior Art
Joining of carbon--carbon composites becomes increasingly important as new technology developments demand larger and more complex geometries. Available joining methods are limited to bonding with adhesive materials, alloy brazing, diffusion bonding, and welding. Joints produced by bonding with adhesive materials or alloy brazing are only suitable for low to intermediate temperature applications, well below the temperature capability of the carbon--carbon composites. Diffusion bonding using refractory metals or compounds usually requires quite careful joining surface preparations of essentially porosity free carbons as well as long heating times at very high temperatures (often &gt;2000.degree. C.) under high pressures. Welding requires even higher joining temperatures, and the joints produced are poor and exhibit low strength. U.S. Pat. No. 5,021,107 describes a process for joining finely finished carbon--carbon composites requiring a joint interlayer thickness of 25-100 micrometers. That process requires rather careful surface preparation and high joining temperatures close to the melting point (TMP, Tungsten is approximately 344.degree. C.) of the joint interlayer material. Furthermore, the strength of the joints, which is low, was not specified in the patent. There is a strong technical need for a process for joining common carbon--carbon composites which requires minimal surface preparation and produces joints having high strength and high temperature application capability. Further needed is a process that produces reliable joints at low temperatures under low pressures.
USPTO Backgrounds
USPTO Backgrounds