In:
Journal of the American Ceramic Society, Wiley, Vol. 100, No. 5 ( 2017-05), p. 2190-2198
Abstract:
Porous silicon oxynitride (Si 2 N 2 O) ceramics were prepared by gas pressure sintering at 1650°C for 2 hour under 1.5 MPa N 2 in two different powder beds, that is, h‐BN/Si 3 N 4 or h‐BN/(Si 3 N 4 + SiO 2 ). Effects of the gaseous atmosphere in the powder bed and the pore diameter in the ceramics on formation of the Si 2 N 2 O phase and the oxidation resistance of the sintered porous ceramics were investigated. Results showed that presence of the gaseous SiO in the powder bed played a crucial role in suppressing decomposition of the Si 2 N 2 O phase at the outer surface of the material. Permeability of the gaseous substances was decreased when the pore diameter was small, to affect the phase composition and the oxidation behavior of the porous Si 2 N 2 O ceramics. The oxidation weight gain curves of the porous Si 2 N 2 O ceramics fitted the asymptotic law. No significant changes in the dielectric constant of the Si 2 N 2 O ceramics were observed after oxidation at 1000°C‐1200°C for up to 30 minutes, whereas the dielectric loss tangent was reduced by oxidation due to formation of SiO 2 . The as‐obtained porous Si 2 N 2 O ceramics could withstand a highest thermal shock of 1200°C when the outer surface could be sealed by the oxidation‐derived SiO 2 layer.
Type of Medium:
Online Resource
ISSN:
0002-7820
,
1551-2916
DOI:
10.1111/jace.2017.100.issue-5
Language:
English
Publisher:
Wiley
Publication Date:
2017
detail.hit.zdb_id:
2008170-4
detail.hit.zdb_id:
219232-9
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