Oxidation resistance and electrical properties of silicon carbide added with Al2O3, AlN, Y2O3 and NiO

Because of its excellent thermal, mechanical and electrical properties silicon carbide is widely used for heating elements. Nevertheless these elements are affected by electrical ageing (increase of electrical resistivity during use). This phenomenon is generally attributed to oxidation but no satis...

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Bibliographic Details
Published in:Journal of materials science 2001-08, Vol.36 (15), p.3793-3800
Main Authors: CHARTIER, T, LAURENT, J. M, SMITH, D. S, VALDIVIESO, F, GOEURIOT, P, THEVENOT, F
Format: Article
Language:English
Subjects:
Additives
Aluminum nitride
Aluminum oxide
Ambient temperature
Applied sciences
Building materials. Ceramics. Glasses
Ceramic industries
Chemical industry and chemicals
Dependence
Electrical properties
Electrical resistance
Electrical resistivity
Exact sciences and technology
Hot pressing
Liquid phase sintering
Liquid phases
Materials science
Nickel oxides
Oxidation
Oxidation resistance
Silicon carbide
Structural ceramics
Technical ceramics
Yttrium
Yttrium oxide
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Summary:Because of its excellent thermal, mechanical and electrical properties silicon carbide is widely used for heating elements. Nevertheless these elements are affected by electrical ageing (increase of electrical resistivity during use). This phenomenon is generally attributed to oxidation but no satisfactory answer has been presently found to reduce its effects. The aim of this study is to obtain a better understanding of the degradation of the electrical properties through the oxidation behavior of hot pressed samples containing various amount of additives. Eight dense SiC ceramic samples with Al2O3, AlN, Y2O3and NiO additives were prepared by hot pressing. The influence of these additives on sintering, oxidation behavior and electrical properties was evaluated. Formation of an yttrium garnet phase leads to liquid phase sintering but decreases the oxidation resistance. The dependence of electrical resistivity with temperature can be explained by the presence or not of a metallic phase formed between Ni and Si. This secondary phase permits a low (< 5 Ω · cm) and almost constant value of the electrical resistivity from ambient temperature up to 950°C to be obtained.
ISSN:0022-2461
1573-4803
DOI:10.1023/A:1017990220468