19 - CVD in Fiber, Powder, and Monolithic Applications

Abstract

This chapter reviews the chemical vapor deposition (CVD) applications, which are not directly related to surface coatings. They are divided into various categories such as: fibers, powders, monolithic shapes, and composites. The boron fibers are one of the earliest commercial applications of CVD. Two fibers that are presently produced by CVD on a commercial scale areboron and silicon carbide. The production of these two fibers uses a monofilament starter core that is capable of being heated resistively, such as a tungsten or graphite fiber. A new process based on laser CVD does not require a core material and is able to produce fibers with a much smaller diameter. Deposition rate is up to 1 mm/sec. This type of process is developed for the production of boron, SiC, and Si3N4. The core-less deposition can be accomplished by impinging the laser beam on the growing end of a retreating fiber in a CVD atmosphere.