Hermetic Reaction Bonded Silicon Carbide Tube Joints with Microwave Heating--FM Technologies, Inc., 10529-B Braddock Road, Fairfax, VA 22032-2236; 703-425-5111
Dr. Ralph W. Bruce, Principal Investigator
Dr. Frederick M. Mako, Business Official
DOE Grant No. DE-FG02-99ER82922
Amount: $750,000

Metal alloy tubes in radiant furnaces, widely used for heat treating of steel, operate in severe environments (for example, temperatures in excess of 1000 degrees Centigrade) and require replacement every 1-2 years. Expenses associated with replacing these tubes (including both downtime and the lost of the tubes themselves) are a significant portion of the life cycle cost of heat treating furnaces. Reaction bonded silicon carbide tubes last 2-3 times longer than metal tubes. However, the required 10-15 foot lengths are available at a competitive cost only as straight tubes, whereas 80 percent of radiant tubes are U, W, or trident shaped. This project will join long straight lengths by forming a silicon carbide-based interlayer in-situ with microwave heating. In Phase I, methods and materials were devised to join short sections of SiC tubes using a proprietary slurry and microwave heating. The resultant tubes were hermetic with the joint strength equivalent to that of the base material. The Phase II project will join prototype length silicon carbide tube sections using liquid infiltration and pyrolysis of preceramic polymer slurries with microwave heating. Long, commercially usable tubes will then be joined and evaluated for industrial applications.

Commercial Applications and other benefits as described by the awardee: 100 billion cubic feet of natural gas is consumed each year in approximately 25,000 heat treating furnaces that use primarily metal radiant burner tubes. Replacement with ceramic tubes would drastically reduce or eliminate tube replacement cost and enable savings of almost $200,000 per furnace per year through increased efficiency of higher temperature operation.

Return to Abstracts' Table of Contents