Sintered composite materials Cr-Al₂O₃

Katarzyna Pietrzak, Marcin Chmielewski Instytut Technologii Materiałów Elektronicznych, ul. Wólczyńska 133, 01-919, Warszawa

Annals 1 No. 1, 2001 pages 16-18

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abstract Among the oxide-metal composites, Al₂O₃-Fe, Al₂O₃-Cr, Al₂O₃-W and Al₂O₃-Ni are of a great technical importance. Recently, because of the situation on the world raw material market and due to the needs of the industry, Al₂O₃-Cr composites have become a subject of special interest. This very hard material, having high mechanical strength, resistant to sudden changes of temperature within the range from 25 to 1300°C, can work at temperatures up to 1000°C. It is also resistant to oxidation at temperatures up to 1500°C. The composite in question can be used to make tools and constructional elements (parts of jet engines, nozzles, crucibles, thermal screens, etc.). This paper presents the results of investigations concerning the sintering of (obtaining by mechanical alloying technique) Cr-Al₂O₃ composite powders. Different sintering temperature and different grain size powders (40÷56 μm - powder 1, 63÷71 μm - powder 2 and 100÷160 μm - powder 3) were examined. The presented paper includes the results: - microstructural investigations (Fig. 2), - diffraction patterns of sintered composites (Fig. 3), - measurements of specific density of sintered composites as the function of the sintering temperature and the grain size of powders (Table 2 and Fig. 4), - measurements of microhardness of composites as the function the sintering temperature and the grain size of powders (Table 3 and Fig. 5).