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.
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