Materials Science Forum, Vol.416-4, 469-474, 2003
Influence of yttrium oxide doping on the microstructures of alumina-niobium carbide composites
Ceramic cutting tools have been developed as an alternative material to cemented carbides based ones with the goal of improving cutting speeds and productivity. Among the vast variety of ceramics considered for prospective use as cutting tools materials the preference is given to the composites containing carbides as a second component, i.e., such materials as Al(2)O(3)-SiC, and Al(2)O(3)-TiC. In the present work, the influence of Y(2)O(3) additives on microstructure of Al(2)O(3)-NbC composite is studied in order to evaluate the applicability of this material for as ceramic cutting tools manufacturing. The amount of Y(2)O(3) additives varied in the ranged, 0-3 wt% in the Al(2)O(3)-NbC 20 wt% composition. Specimens were produced by consequent uniaxial and isostatic pressing followed by pressureless sintering in the flowing argon at 1750 degreesC for 15 min in a graphite resistance furnace. The achieved densities were up to 99% TD. Microstructure evaluation in terms of grain size distribution were achieved by mean of QUANTIKOV software applied to scanning electron microscope (SEM) micrographs. Optimization of the materials composition in regard of achieving the high densities without compromising the microstructure formation are discussed.