Ceramic Composite Lift Fan Clutch Plates with Improved Tribological Behavior

The STOVL version of the Joint Strike Fighter utilizes a clutch to engage the lift fan. The clutch plates must dissipate large amounts of frictional energy introduced at a very high rate during engagement. Current carbon/carbon clutch plate materials donot possess the desired range of static and dynamic friction coefficients, and require more frequent servicing than other lift fan clutch components. The utilization of a ceramic-carbon hybrid matrix, where the ceramic is selected for improved heatcapacity and reduced wear and the carbon constituent is optimized for thermal conductivity utilizes the strengths of all of the constituent materials. The hybrid ceramic-carbon matrix composite is anticipated to have a higher heat capacity, higher thermalconductivity, and result in a lower wear rate and more stable friction coefficient as compared to current materials. Both silicon carbide and boron carbide hybrid matrix composites will be fabricated and their mechanical, thermal, and high energytribological behavior will be evaluated with respect to the requirements of the JSF lift fan clutch.