Induction of through-thickness temperature gradients in thin shell ceramic composite cylinders by thermal radiation

Silicon carbide matrix composites are candidate materials to serve as high-temperature combustor liners. This application exposes the liner to thermal gradients through the thickness, which contribute major sources of stress. To evaluate the liner's potential performance, thermal gradients were induced with an axisymmetric direct-current electric arc lamp within a thin shell ceramic composite cylinder. Simultaneously, the outer surface of the shell was cooled with refrigerated air. With the arc lamp emitting full spectrum visible light, radiant intensity exceeded 20 W/sq cm to produce temperatures as high as 1200 C. The purpose of this investigation was to create a test system which would allow fast heating and thermal evaluation of complex three-dimensional ceramic composite components. A test system was developed to induce thermal gradients within SiC fiber-reinforced silicon carbide matrix composite cylinders. Because the system does not rely upon the combustion of fuels to achieve the desired thermal conditions, ancillary environmental reactions are essentially eliminated, thereby allowing a pristine observation of the cylinder's thermal and mechanical response. The test system is described in this paper, and representative results of the system's performance are given with respect to absolute temperature and thermal gradients. (CSA)