Synthesis of Si3N4-celsian composite materials

To obtain celsian, two different types of additive were used. In the first case, a mixture of BaCO3, Al2O3 and SiO2 was added to Si3N4, while in the second case, a Ba-A-zeolite, previously heated at 850C, was used. Mixtures of Si3N4 and the sintering aids were homogenised in a vibratory mill in the...

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Bibliographic Details
Published in:Ceramics international 2000, Vol.26 (1), p.33-37
Main Authors: BOSKOVIC, S, KOSANOVIC, D, DONDUR, V, DIMITRIJEVIC, R
Format: Article
Language:English
Subjects:
Applied sciences
Building materials. Ceramics. Glasses
Ceramic industries
Chemical industry and chemicals
Exact sciences and technology
Structural ceramics
Technical ceramics
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Summary:To obtain celsian, two different types of additive were used. In the first case, a mixture of BaCO3, Al2O3 and SiO2 was added to Si3N4, while in the second case, a Ba-A-zeolite, previously heated at 850C, was used. Mixtures of Si3N4 and the sintering aids were homogenised in a vibratory mill in the presence of isopropanol. The green bodies were pressurelessly sintered in a nitrogen atmosphere at temperatures of 1650-1750C. The degree of densification and microstructural changes were studied as a function of the sintering conditions and the additive used. Reaction of BAS formation was followed by X-ray analysis during the heating period. With 10% zeolite as a sintering aid, full densification was achieved at 1750C but with the same amount of oxide mixture, only 96% TD was attained. Phase changes were followed during cooling of the samples from the sintering temperature. Two crystalline phases, beta-Si3N4 and hexacelsian, were present in both types of sintered samples. 16 refs.
ISSN:0272-8842
1873-3956
DOI:10.1016/S0272-8842(99)00016-4