Low Cost 2D Laminated Ceramic Composites with Improved Interlaminar Strength

The objective of this proposed effort is to demonstrate a ceramic composite material having improved interlaminar properties over typical fabric laminates using a commercially available textile process. Affordable fiber preforms using multiple plies of woven CG-Nicalon fabric will be dry-laminated and compacted in a perforated tooling fixture to the requisite fiber volume fraction. The preforms will undergo a thru-thickness needle punching process where a barbed needle will be used to pierce, draw and reorient a small fraction of the fiber in the out-of-plane, "z" direction while serving to mechanically interlock the layers of fabric within the laminate. Needle punching corresponds to the pattern of perforated holes in the preform tooling fixture. The density, or fraction of fiber reoriented in the "z" direction is therefore dependent on the pitch or spacing of these holes where the barbed needle passes. Several laminated preforms will be produced with increasing thru-thickness needling (increasing fractions of "z" fiber reinforcement) and then densified with silicon carbide produced by CVI. Coupon specimens from the various composite systems produced will be evaluated to determine their respective in-plane and interlaminar mechanical properties. These results will be compared to a "baseline" un-needled fabric laminated composite system to establish the overall viability of the proposed approach.