Premium
High‐Temperature Hydroxylation and Surface Corrosion of 2/1‐Mullite Single Crystals in Water Vapor Environments
Author(s) -
Eils Nadine,
Rüscher Claus H.,
Shimada Shiro,
Schmücker Martin,
Schneider Hartmut
Publication year - 2006
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2006.01170.x
Subject(s) - mullite , corrosion , crystal (programming language) , materials science , single crystal , decomposition , analytical chemistry (journal) , absorption (acoustics) , diffusion , mineralogy , chemistry , inorganic chemistry , crystallography , metallurgy , composite material , ceramic , organic chemistry , physics , computer science , thermodynamics , programming language
2/1‐mullite single crystal (001) plates with thicknesses between 0.9 and 1.9 mm were exposed for 1.5, 3, 6, and 12 h at 1670°C to a slowly flowing (100 mL/min) water‐rich gas mixture (O 2 /H 2 O 80/20). Under the given experimental conditions, 2/1‐mullite yielded significant amounts of structurally bound OH groups across the bulk and decomposition of the crystal surface on a micrometer scale. Decomposition products are (i) sodium‐containing silicon‐rich alumino silicate glass formed from melt and (ii) α‐alumina, which crystallizes within melt cavities. The crystal plates that are free of any OH absorption before the corrosion experiments show a steep increase in OH absorption intensity up to 3 h of corrosion and a flattening toward longer times of exposure. The evaluation of OH intensity profiles implies an effective diffusion coefficient D H in the range between 1.5 and 2.5 × 10 −7 cm 2 /s.