THE EFFECTS OF BINDERS AND HEATING TEMPERATURES ON THE PROPERTIES OF PREFORMS

The use of binders in fabricating ceramic fiber preforms is essential when producing metal-matrix composites via squeeze casting or liquid metal infiltration. The binder is not only used to stabilize the shape of the preform, but also to increase its strength. A strong preform is needed to make a net shape or near-net shape casting so that many post-machining processes can be reduced or eliminated. However, very little attention has been paid to preform fabrication, subsequent processing, and its characterization. This work focuses on the relation between preform processing (selection of binder, heat treatment of the preform, etc.) and the properties of the resulting preforms. Silica and phosphate binders were used to make short alumina fiber preforms. The use of binders and the heat treatments used were correlated to the properties of the resulting preforms. The results showed that the heat treating temperature, as well as the amount of binder, is relevant to the resulting properties of the preform. Correlations among the use of binders, heat treatment condition, composition of the binders, and the properties of the preforms were investigated.