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The possibility of producing aluminium matrixed aluminium nitride-boron carbide composites by pressureless wetting assisted infiltration has been shown. Cold isostatically pressed cup-shaped preforms of boron carbide (1-10 wt%) aluminium nitride mixtures were sintered at 1400-1600 degrees C in nitrogen atmosphere and then infiltrated with aluminium under 6.5 kPa argon at 1250 degrees C. Pore diameter in the preforms increased with increase in sintering temperature. Infiltrated samples which were sectioned and polished showed no infiltration front. Higher B4C contents (4-10%) and sintering temperature (1600 degrees C) resulted in full infiltration. In the sintered preforms AlN was the only phase observed. However, in the infiltrated materials both AlN and Al were observed. (C) 1997 Elsevier Science Limited and Techna S.r.l.

Alumina based ceramic-ceramic composite thread-guide samples were fabricated using a low-pressure injection-molding technique. Major processing steps in this method are introduced, and binder development and binder removal studies of a specially formulated multicomponent binder composition are described. It is illustrated that the wicking process is beneficial to shorten the processing time. Microstructural features after debinding, the sintering stage and application in field testing are outlined. The sample hardness was determined to be lower than that of pure alumina-based thread guides, allowing less wear damage to fibers. The results indicate that low-pressure injection molding can be employed as a potential forming technique for the fabrication of ceramic thread-guide components used in the textile industry.

Even although advanced ceramics can be considered to be in their early development phase in Turkey, there is great potential for their advancement. Growth in the markets and in the technological needs for these materials in high technology applications have recently accelerated. In this paper, activities related to advanced ceramics both in research and industry are reviewed and a preliminary estimate of the market potential, based on the present status and future estimates, is presented. The review covers powder synthesis and production of advanced structural and functional ceramics. (C) 1994 The Institute of Materials.

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