Nippon Carbon (Tokyo, Japan), GE Aviation (Newark, Del.) and Snecma (a subsidiary of Safran, Courcouronnes, France) recently formed a joint venture, NGS Advanced Fibers Co. Ltd. (Tokyo, Japan) to manufacture and sell silicon carbide (SiC) continuous fiber under the trade name Nicalon. The deal is expected to ensure a consistent supply of ceramic-matrix composites (CMCs) for GE and Snecma as demand for the material rises. For now, yarns of 20-µm SiC fibers produced by Nippon are used by GE in the CMC manufacturing process. During manufacture, the fibers are first coated with a 1-µm thick proprietary coating and then passed through a slurry bath. Rigid tapes are made into ply layups and cured in an autoclave. Next, a hot oven burns off organic compounds, leaving a near net-shaped part made of porous ceramic-coated SiC fibers. These parts are then placed in a melt infiltration chamber where silicon is reacted with the remaining carbon to form the CMC. The completed CMC is 98 percent dense and requires hard diamond grinders for finish work.
Lightweight, hard and stable at high temperatures, CMCs are emerging from two decades of s...