ISSN:
1551-2916
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Analytical and high-resolution transmission electron microscopies were used to study the structure and chemistry of two-grain boundaries and three-grain junctions in polycrystalline alumina sintered with additions of between 0 and 10 wt% calcium silicate. Addition of calcium silicate greatly aided full densification and resulted in the presence of a continuous, amorphous grain-boundary film at the majority of the two-grain boundaries, the thickness of which was independent of the bulk level of additive. The chemistry of the glass at the grain boundaries and the three-grain junctions was notably different. The grain boundaries showed strong segregation of calcium, whereas both silicon and calcium appeared to favor triple pockets and larger-volume facets at the grain boundaries. Grain-triple-pocket interfaces also showed segregation of calcium. The overall extent of segregation appeared to be independent of the additive level. The amorphous grain-boundary film was of nominal composition CaO6Al2O3 and contained predominantly octahedrally coordinated aluminum within the glass. The triple pockets were generally of a composition within the primary-phase field of anorthite and contained tetrahedrally coordinated aluminum and silicon.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1151-2916.1998.tb02343.x
