SBIR-STTR Award

Continuous fiber reinforced ceramic matrix composites (CMCs) are desired for aerospace applications due to the strength and toughness imparted by incorporation of embedded long fibers of carbon or silicon carbide into a ceramic matrix. Oxidative degradation at high temperature is the predominant factor limiting the use of CMCs in jet engine applications. The components can swell when heated in air, which suggests poor interlaminar tensile (ILT) strength. A method for measurement of ILT strength of CMCs at the high temperatures to which they are exposed (2300 °F) is highly desired by engine developers and the composites R&D community, but extension of the testing standard is not possible without development of an ultrahigh temperature adhesive. This program will utilize a new high-yield ZrB2 ceramic derived from polymer precursor to demonstrate the feasibility of using a ceramic cement to enable ILT strength testing at high temperature in air. Thor Technologies has teamed with the Materials Engineering Group of Southern Research Institute and a provider of SiC test fixtures to plan and execute the following proposed effort, which will combine the new precursor with appropriate additives for surface fluxing, to achieve reactive bonding of the cement to the CMC surface.

Keywords:
Cmc Cement Adhesive Ceramic Interlaminar Tensile Testing

This Phase II effort will demonstrate a standard method of measuring the high-temperature, inter-laminar tensile (HT-ILT) strength of ceramic-matrix composites (CMCs). Jet engines with higher turbine gas temperatures for higher specific thrust and efficiencies require the use of SiC/SiC CMCs with known mechanical properties at high temperature (2300 °F). The typically poor ILT strength of CMCs containing 2-D woven fibers imposes artificial limits on the design of hot section components. The method is needed by engine developers to avoid the expense of over-built airfoil components, particularly rotating components. It would not only help determine the design limits of CMC materials, but also aid the discovery of ways to improve ILT strength. Furthermore, HT-ILT testing could be used to screen materials for processing defects and qualify them for service (i.e., quality assurance testing as well as studies of material fatigue). The program will extend the room-temperature method, ASTM C1468 for ILT testing of CMCs, to testing at =2400 °F, by demonstration and validation of a new ceramic-based adhesive capable of 6 ksi strength at high temperatures.

Keywords:
Interlaminar Tensile Strength Ilt Ceramic Cement Composite Material, Interlaminar Tensile Strength Ilt Ceramic Cement Composite Material