SiC whisker- and C fiber-reinforced calcium phosphate composites

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SiC whisker/calcium phosphate and C fiber/calcium phosphate composites were fabricated by hot-pressing at 1185 °C and 7.6 MPa in vacuum. The microstructural characteristics, especially interfaces, of these composites were studied using transmission electron microscopy. The mechanical properties of these composites were measured by four-point bending tests. It was found that the mechanical properties of these calcium phosphate-based composites were strongly dependent on their microstructural characteristics.

The ideal biomaterials for bone replacement in the fields of oral and plastic surgery demand biocompatibility, mechanical suitability, and ease of handling in an operating room environment. Biomaterials must also be easily sterilized and fabricated and be available at a reasonable cost.1 Biocompatibility, or the acceptance of a material by the body's immune system, is especially critical in the successful use within the human body. Calcium phosphate ceramics are widely accepted since their elemental components are present in bone naturally. However, the ceramics are extremely brittle so that they fail in a brittle fashion with very little deformation to failure. This can be a major problem when they are utilized in weight-bearing areas of the human body. Recently, in order to improve the mechanical properties of biomaterials, a large number of studies are focusing on polymer- and ceramics-based composites.2 To our knowledge, calcium phosphate-based composites have not been reported. In this study, we attempted to reinforce the calcium phosphate ceramics by the incorporation of SiC whiskers and C fiber. In order to fabricate the SiC whisker (5 vol. %)/ calcium phosphate (denoted by SC) composite, calcium phosphate powder and SiC whiskers were mixed by a ball-milling for 30 min in methanol. The calcium phosphate powder and SiC whiskers were supplied by Fisher Scientific Company and Textron Specialty Materials, respectively. The resulting slurries were dried, and mixed again by a ball-milling for 5 min to remove agglomerates, and then loaded into a mold. In order to fabricate the C fiber (5 vol. %)/calcium phosphate (denoted by CC) composite, calcium phosphate powder and chopped C fiber were mixed by a blender in water. The C fiber was supplied by Amoco Oil Company. The resulting slurries were dried and then mixed by a ballmilling for 5 min. The mixture was dried completely. The dried mixture was then blended by a blender again to remove agglomerates and then loaded into a mold. Sub2476

http://journals.cambridge.org

J. Mater. Res., Vol. 9, No. 10, Oct 1994

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sequently, the SC and CC composites were fabricated by hot-pressing at 1185 °C and 7.6 MPa for 30 min in vacuum. The open porosity of the composites was determined in accordance with ASTM C 373. 3 The mechanical properties of the composites were measured at room temperature by four-point bending in accordance with ASTM D 7904 using an Instron Testing Machine. The microstructural characteristics, especially interfaces, of these composi