Higher strength and lighter weight fiber reinforced ceramic, polymer, and metal composites require stronger and more thermally stable fiber materials. Such improvements require the ability to grow, process, and test fibers at higher temperatures than presently possible in a practical manner. This project will evaluate the technical feasibility of producing, enhancing, and testing fibers used in production of reinforced fiber composites by applying ultrahigh solar flux. Generally, it is preferable to heat such fibers radiantly. To do so practically at temperatures higher than 1,500øC, ultrahigh solar concentration will be used. In Phase I, the feasibility of developing a two-stage non-imaging optical solar concentration system to reach temperatures between 1,500øC and those approaching the sun's surface temperature within a small-diameter cylindrical hot-zone will be assessed. The procedures used previously to develop non-imaging designs to couple the nearly collimated solar radiation to a point of ultrahigh solar concentration will be extended to the present case. An analogous two-stage fiber furnace that properly couples the solar energy to a cylindrical line of ultrahigh concentration will be designed. Computer programs will be developed to design and ray-trace the needed non-imaging element. In this manner, a complete system simulation will be made in terms of the secondary or non-imaging element's input and output flux distributions and dependence on optical design parameters. The indicated prototype optical concentration system will then be constructed so that brassboard measurements of the resulting temperature can be made. Both optical pyrometry and tungsten wire resistance methods will be used to confirm and calibrate temperature. If the technical merit of high temperature fiber processing and testing through the application of ultrahigh solar energy concentration is demonstrated, a Phase II program to build and test a working prototype will be conducted. Experimental results will then be used and scaled to develop the design for a practical solar furnace station for fiber processing and testing.Anticipated Results/Potential Commercial Applications as described by the awardee:If this project is successful, the technical feasibility of an energy-efficient means of supply will be demonstrated for the improved fiber materials particularly needed in environmentally harsh aerospace and engine applications. DOE will benefit from the use of these improved fibers in a variety of gas combustion and turbine applications. Through these new and high value applications, DOE also will stimulate a greater use of existing and planned national solar energy facilities and will otherwise broaden the applications of concentrated solar energy. Higher temperature fibers are also needed in various Department of Defense and National Aeronautics and Space Administration applications associated with the skin and structural parts of aircraft, space vehicles, platforms, and satellites, as well as with many defense-related weapon and missile systems
