OHN LINCOLN, BARRETT JACKSON, AMY BARNES, AARON BEABER, LARRY VISSER
Axiom Materials, Inc., Santa Ana, CA 92705; email@example.com
Composites Horizons, Covina, CA 92697-7075
3M Company, Advanced Materials Division, St. Paul, MN 55144
Oxide-oxide ceramic matrix composites are gaining increasing attention as a mainstream material option for high temperature components in the aerospace and advanced energy sectors. As the material moves from bench to production, cost reductions are required to ensure that the solutions are market-competitive with titanium and other high temperature alloys. In parallel, a more comprehensive portfolio of fabric geometries and data are desirable to enable flexibility in both engineering and design. 3M, maker of Nextel™ ceramic fibers, joins CMC prepreg developer and manufacturer, Axiom Materials, Inc., and CMC parts designer and fabricator, Composites Horizons, in developing data for the present work. The team jointly compares the properties of Oxide-Oxide CMCs fabricated from conventional Nextel fabric architectures with those of new, lower cost fabric designs.
Oxide-oxide ceramic matrix composites (OxOx CMCs) now have significant application momentum in oxidation-sensitive component applications. Yet both the transition to OxOx CMC, as well as the engineering of new OxOx CMC hardware, has been gradual as a result of its high cost relative to conventional materials or as an element of any new component design. The global market for OxOx CMC components is positioned for near-term growth and on the cusp of mainstream adoption provided that reasonable cost profiles can be achieved. Particularly in the case of the aerospace sector, cost reduction initiatives have become especially high-priority as the OxOx CMC cost / value proposition crosses that of machined titanium components for turbine engine and other high temperature hardware. The present work seeks to provide engineering solutions for cost-conscious OxOx CMC design through (a) the development of lower cost fiber and fabric architectures, and (b) characterization of their physical and mechanical properties.
Indeed, there is precedent in using higher denier fibers and fabrics to achieve reduced costs. Similar trends have been observed for carbon fiber composites, which has progressed from 1k and 3k fibers initially, to upward beyond 50k fibers to reduce the cost of finished components.1 Like carbon components, costs associated with the manufacturing process for OxOx CMC components are weighted heavily toward the cost of the fiber and/or fabric. Insofar as these costs can be reduced, component level costs can likewise be reduced. To date, most OxOx CMC technical property data and research has been based on the use of NextelTM 610 and 720 fibers,2-7 and most notably styles DF-11 and EF-11 (1500 denier). The 1500 denier yarns are the finest produced commercially and are the most expensive fibers from a manufacturing standpoint due to small fiber bundle size and high demand placed on fiber manufacturing lines. 3M has demonstrated that higher denier yarns may be made by increasing the number of filaments in the tow bundle and keeping the individual filament diameters similar, 8 which results in a significant cost advantage in fiber production. As the cost savings available from higher deniers of the Nextel fibers are of primary interest, relative costs of various fiber deniers are presented in Figure 2. The fiber types used in the present study for both grades Nextel 610 and 720 are 1500, 3000, 4500 and 10,000 denier.