N092-115 TITLE: Innovative Approaches to Develop Foreign-Object-Damage (FOD) Resistant Ceramic Matrix Composites (CMCs)

TECHNOLOGY AREAS: Materials/Processes

ACQUISITION PROGRAM: F-35/Joint Strike Fighter

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.

OBJECTIVE: Develop and demonstrate innovative FOD resistant SiC fiber-based CMCs.

DESCRIPTION: CMCs are currently being considered and used for aeroengine airfoil applications with a goal of increased specific power. Concerns exist regarding the degradation of CMCs due to life limiting phenomena related to thermal, chemical, and environmental effects of those materials. Of a particular concern is impact damage by small foreign objects such as sands, loosened metallic particles, and/or other objects ingested into airfoils. Existing CMC material systems have shown inferior resistance to FOD. Since CMCs are brittle and CMC airfoils are typically in a thin configuration (less than 1/8") [1], the impact generates a varying degree of damage from localized surface damage, to subsurface damage, to complete penetration, depending on the severity of impact events [2]. It has been shown that even small steel projectiles with a diameter of 1/16" (=1.59 mm) could penetrate melt-infiltrated (MI) SiC/SiC or oxide/oxide CMC plates at impact velocities >300 m/s [2,3]. Generation of FOD in CMC airfoils can result in a premature component life and a loss of related functions, thus significantly limiting the use of CMCs in aero-applications. Therefore, from a durability and affordability prospective, it is highly desirable to develop FOD resistant, SiC fiber-reinforced CMCs through an innovative approach that could outperform the existing CMC material systems previously considered [2].

PHASE I: Develop innovative approaches to enhance FOD resistance of SiC fiber-based CMCs. Demonstrate conceptually the feasibility of the CMC material systems.

PHASE II: Fully develop and optimize the approach formulated in Phase I. Fabricate and evaluate the prototype CMCs in terms of FOD durability through appropriate tests using a reasonable number of test coupons.

PHASE III: Perform validation and certification testing and transition the approach to interested platforms and other propulsion applications.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: CMCs propulsion components have a great potential to transition to the civilian aeroengine applications. The resulting material development, albeit risky, could allow an eventually significant cost saving while the developed material could outperform the conventional CMC systems. The development will also open a new means of material fabrication and component designs.

REFERENCES:
1. D.N. Brewer, M. Verrilli, and A. Calomino, "Ceramic Matrix Composite Vane Subelement Burst Testing," Proceedings of ASME Turbo Expo 2006, ASME Paper No. GT2006-90833 (2006).

2. S.R. Choi, "Foreign Object Damage Phenomenon by Steel Ball Projectiles in a SiC/SiC Ceramic Matrix Composite at Ambient and Elevated Temperatures," Journal of the American Ceramic Society, 91[9] 2963-2968 (2008).

3. S.R. Choi, D.J. Alexander, and R.W. Kowalik, "Foreign Object Damage in an Oxide/Oxide Composite at Ambient Temperature," Proceedings of ASME Turbo Expo 2008, ASME Paper No. GT2008-50505 (2008); Also in Journal of Engineering for Gas Turbines & Power, 130 (2009).

KEYWORDS: Ceramic matrix composites (CMCs); foreign object damage (FOD); SiC fiber reinforced CMCs; impact; impact testing; ballistic impact

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