SiC Manufacturing Advances Aid Next-Generation Engine Technology

  • Published
  • By Heyward Burnette
  • Materials and Manufacturing
WRIGHT-PATTERSON AIR FORCE BASE, Ohio --  Air Force Research Laboratory's Manufacturing Technology Division and GE Aviation are transitioning state-of-the-art technologies related to the improved manufacture of coated silicon carbide fibers--which, as vital materials in the development and maturation of ceramic matrix composite engine components, contribute to reduced cost and better performance for weapon systems. Specifically, the use of SiC-based CMCs for engine components lowers fuel costs by replacing metal alloys, a substitution that decreases weight and, in turn, improves speed and acceleration. Experts anticipate that the introduction of SiC CMCs into a single aerospace engine alone--the T700, used in the Apache, Blackhawk, Knighthawk, and other next-generation aircraft--will save one million gallons of fuel annually.

Current superalloy turbine engine components are heavy compared to CMCs. This excess weight negatively impacts engine fuel efficiency and prompts repeated repairs, contributing to higher life-cycle costs for aerospace systems. Reducing the weight of turbine engine vanes by replacing metal alloys with CMCs improves engine fuel economy as well as performance. Further, the improved durability of CMC components translates to less frequent maintenance and, consequently, lower life-cycle costs.

The AFRL/industry team's Ceramic Matrix Composite Manufacturing Initiative (a Defense-Wide Science and Technology-driven effort) involves both the conversion of a multistep batch process for coating fiber tows into a single-step process and the improvement of corresponding machine parameters and cycles. To date, project engineers have implemented a 100% increase in the coating run length with existing equipment. The implementation has increased coating capacity from 137 m to 275 m of fiber. With the resulting materials having undergone successful validation during CMC panel fabrication and mechanical property testing, the project's ultimate goal is a 550 m capability, with SiC prepreg system demonstration slated for later this year.