Abstract: A fabrication process is disclosed that achieves a higher density carbon-bon article, than the prior art processes by maintaining a vertical temperature gradient in a reservoir of pitch (e.g. 550.degree. C. at the bottom to 250.degree. C. at the top) into which a carbon fiber preform is immersed. The use of the vertical temperature gradient results in a reservoir of hot fluid pitch around the upper end of the preform during pitch impregnation of the preform. This permits the fluid pitch to drain down by gravity into the interstices of the carbon fiber and the hardening pitch below. The next step of the process involves gradually increasing the pitch-hardening temperature from bottom to top to harden the pitch from bottom to top. Thereafter, the impregnated preform is carbonized at high temperature. This method takes advantage of the thermal conductivity of the carbon fibers and does not require extremely high pressures. In fact, a high pressure would be a detriment since it results in closed pores.

Abstract: A method for effecting repairs of the damaged components of a machinery in he field which would otherwise require high temperature treatment of the damaged components to form a metal-oxide epoxy joint in a shop. The method includes preparing a repair patch which includes a metal sheet with the metal oxide layer thereon, applying a thin high performance protective coating thereover, covering thereof with a sacrificial backing sheet and then curing the adherent-top coat backing sheet to form a highly durable bonded system which can be stored until needed. At the time of repair the backing sheet is removed by sanding or grit blasting and the adherent is applied to the structure to be repaired under ordinary temperature conditions.

Abstract: Polyacrylonitrile (PAN) based fibers are stabilized by heating them in an atmosphere containing oxygen and ammonia from room temperature to 150.degree.-350.degree. C., prior to carbonization and high-temperature treatment or graphitization to form carbon fibers. PAN fibers stabilized in presence of oxygen and ammonia have a higher density, and the time required for stabilization is shortened compared to being stabilized with air in the absence of ammonia, stabilization in absence of oxygen and ammonia, and stabilization in pure ammonia.