Manufacture and Characterization of Oxide Ceramic Matrix Composites out of Commercial Pre-Impregnated Fabrics

In this work, a recent production technique of oxide ceramic matrix composites with a porous matrix based on commercial prepregs from Axiom, USA, was developed and investigated. The main objectives were to study the influences of the different prepreg types and the manufacturing process on the material properties. Two commercially available prepregs - Nextel (TM) 720 fabric with alumina-silica matrix based on a non-aqueous slurry and Nextel (TM) 610 with alumina matrix based on an aqueous slurry - are processed with the simple techniques of laminating, warm pressing, drying and sintering. The manufacturing process has been defined on one hand based on the prepreg manufacturer's recommended curing cycle as well as based on thermogravimetric analysis. On the other hand, standard-processes from own know-how were used which are based on the wet layup technique with fabrics infiltrated by hand. The manufacturer of the prepreg recommended curing via warm compression or autoclave process. The autoclave process has been pushed aside in order to significantly reduce production costs. The matrix composition has been analyzed after different processing steps. Bending and shear tests showed the influence of the different prepregs and thermal treatment on mechanical properties. Based on experimental results from microstructural analysis and mechanical testing, it was shown that prepregs out of alumina fabric with an aqueous alumina matrix are suitable for the production of the all-oxide CMCs.