Abstract: In one aspect, a ceramic matrix composite sandwich structure has a ceramic honeycomb core structure, a first face sheet on a first surface of the ceramic honeycomb core structure, and a second face sheet on a second surface of the ceramic honeycomb core structure. Methods of preparing the ceramic matrix composite sandwich structure involve applying ceramic matrix composite prepregs to a honeycomb core to form an unbonded sandwich structure, subjecting the unbonded sandwich structure to an autoclave process to form an intermediate bonded sandwich structure, and subjecting the intermediate bonded sandwich structure to a sintering process to produce the ceramic matrix composite sandwich structure.

Abstract: A method of fabricating a ceramic matrix composite material into a part, including applying a semi-permeable membrane over a stack of composite plies pre-impregnated with ceramic matrix. The semi-permeable membrane comprises a porous plastic material and may have a thickness of approximately 0.002 to 0.008 inches. The method may include compressing the semi-permeable membrane and the stack together and heating the semi-permeable membrane and the stack to cure the stack into the composite part. The semi-permeable membrane may be a porous plastic having pores large enough to allow volatile gasses to escape therethrough during curing but equal to or smaller than solid ceramic particles or clusters of the solid ceramic particles suspended in the ceramic matrix. The composite plies may contain approximately 35 percent to 45 percent of the ceramic matrix by weight relative to an overall weight of the stack of the composite plies pre-impregnated with the ceramic matrix.