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Corrosion Behavior of Silicon Carbide in 290°C Water
Author(s) -
Hirayama Hideo,
Kawakubo Takashi,
Goto Akira,
Kaneko Tadashi
Publication year - 1989
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.1151-2916.1989.tb06029.x
Subject(s) - corrosion , dissolution , silicon carbide , chemical engineering , inorganic chemistry , materials science , carbide , ceramic , diffusion , chemistry , oxygen , metallurgy , thermodynamics , physics , organic chemistry , engineering
The fundamental corrosion behavior of silicon carbide (SiC) ceramics was investigated after immersion in 290°C water solutions with different pH and dissolved‐oxygen concentrations. The weight loss in the oxygenated solution was more than that in the deoxygenated solution and was accelerated by increasing pH. Preferential attack could be found at grain boundaries and around pores on the sample surface immersed in the oxygenated alkaline solution. The weight change, dW, followed the general rate law, (dW) m = kt. The exponent, m, was 1.11 in the alkaline solution and 0.45 in the acidic solution. Based on the above results, the SiC was considered to be directly hydrolyzed to a silica sol, with its dissolution kinetics dependent on the sol stability. This corrosion behavior is quite different from those in high‐temperature or vapor‐phase hydrothermal oxidation, where the oxidation rate is controlled by oxidant diffusion through the protective silica surface layer.