Sintering of alumina niobium carbide composite

Several studies have been focused on particulate-dispersed Al(2)O(3) composites in order to improve both room and high temperature mechanical properties and wear resistance. In the present work Al(2)O(3)-NbC composites have been pressureless sintered and their microstructures analysed as a function of NbC and Y(2)O(3) concentration, the latter added as sintering aid. The compositions used in this study were Al(2)O(3)-xNbC and (Al(2)O(3) 3%Y(2)O(3))-xNbC, (X = 10, 20 and 40 wt%) and the sintering was performed at 1650 degrees C/30 min and 1750 degrees C/15 min. A density greater than 96% of the theoretical density was reached even for those materials sintered at 1650 degrees C. The observed microstructure was more homogeneous for the samples with Y(2)O(3) addition and the Y(3)Al(5)O(12) phase was detected. The Al(2)O(3) grain growth restraining due to the NbC concentration was more pronouncedly in samples sintered at 1750 degrees C. (C) 1998 Elsevier Science Ltd. All rights reserved.