THE POTENTIAL APPLICATION OF NATURAL MINERALS IN CERAMIC AND METAL-MATRIX COMPOSITES

Current practice in advanced materials processing has involved the dis persion of a second-phase, commonly SiC, glass, or other non-metallic fibres/whiskers/particulates to enhance physical characteristics of th e matrix These matrices may be either ceramic or metallic but in eithe r case it is important that the physical and chemical properties of ea ch phase be compatible. The dispersed, finely-divided second phase is often both expensive and foreign-produced and may exhibit chemical ins tability at elevated temperatures. Thus, it would appear that certain naturally-occurring industrial mineral fibres/whiskers/particulates mi ght offer an attractive and low-cost alternative. Suitable candidates, such as wollastonite and sillimanite, are available in Canada and may be milled to produce particles whose shape is appropriate for this ap plication. It is suggested that wollastonite, in particular, may be a useful modifying agent in metal-matrix composites utilizing Al, Al-Si, Zn-Al or other light metals and alloys In addition, the possible use of these minerals in ceramic-matrix materials is also addressed, with reference to a preliminary thermodynamic analysis of the system involv ed.