EFFECT OF SINTERING ATMOSPHERE ON THE MECHANICAL-PROPERTIES OF NI AL2O3 COMPOSITES/

In the present study, nickel-toughened aluminas are prepared by sinter ing in either hydrogen or carbon monoxide. By choosing suitable sinter ing temperatures, the size of nickel inclusions is the same in the com posites sintered in H-2 and CO. The addition of nickel inclusions enha nces the toughness of alumina. As the inclusion size is bigger than 2 . 7 mu m, microcracks are formed at the interface in the composites si ntered in H-2. The toughness and strength of the composites are thus r educed. However, no microcracks are observed at the interface in the c omposites sintered in CO. The toughness and strength of the composites sintered in CO is therefore higher than those of the composites sinte red in H-2. For example, for the composite containing 20 vol% inclusio ns and sintered in CO, the roughness is 9 MPa m(0 . 5) and the strengt h is 630 MPa. (C) 1997 Elsevier Science Limited. All rights reserved.