| Autor: | Ulrich Vogt, K. Berroth, Georges Chollon |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Amorphous silicon
Materials science Silicon Annealing (metallurgy) Mechanical Engineering Analytical chemistry Mineralogy chemistry.chemical_element Partial pressure Amorphous solid law.invention chemistry.chemical_compound chemistry Mechanics of Materials law Ultimate tensile strength General Materials Science Limiting oxygen concentration Crystallization |
| Zdroj: | Journal of Materials Science. 33:1529-1540 |
| ISSN: | 0022-2461 |
| DOI: | 10.1023/a:1017555518483 |
| Popis: | Si–N–(O) fibres were grown according to a high temperature vapour–solid process involving the reaction between SiO and NH3 on a substrate. The oxygen concentration of the fibres is related to the partial pressures of SiO and NH3 during fibre growth, depending respectively, on the processing temperature and the ammonia flow rate. The fibres consist of amorphous silicon oxynitride of composition Si02xN4(1−x)/3 (0.1 < x < 0.2). They exhibit a large spread in tensile strength. The lowest values (about 1 GPa) correspond to large surface defects caused by intergrowth while the highest values reach 5 GPa for perfect fibres. The fibres are stable in nitrogen up to 1450 °C (10 h) in terms of composition, structure and mechanical behaviour owing to their high processing temperature (1450 °C) and the nitrogen pressure preventing decomposition. A superficial crystallization into Si3N4 is only observed at 1500 °C inducing a moderate decrease of strength. In argon, decomposition starts at 1400 °C yielding gaseous species (SiO and N2), crystalline Si3N4 and free silicon beyond 1400 °C and induce a catastrophic drop of strength. Annealing in oxygen results in a growth of a protective SiO2 scale, amorphous or partially crystalline at 1400 °C. |
| Databáze: | OpenAIRE |
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