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Oxidation and Corrosion of SiC (particulate) /Al/Al 2 O 3 Composites in Sodium Silicate at Elevated Temperatures
Author(s) -
Kern William A.,
McNallan Michael J.,
Tressler Richard E.
Publication year - 1996
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.1151-2916.1996.tb08009.x
Subject(s) - corrosion , materials science , oxidizing agent , metal , sodium silicate , silicate , composite number , ceramic , metallurgy , composite material , chemical engineering , chemistry , organic chemistry , engineering
Ceramic‐matrix composites (CMCs) fabricated by the directed metal oxidation process (Dimox TM ) may have applications in heat exchangers in high‐temperature corrosive environments such as those in the glass industry. The oxidation and corrosion properties of such CMCs with and without preformed metal‐free surface layers have been investigated in the temperature range of 1000–1300°C. The untreated CMCs experienced rapid oxidation in air leading to mass increases of 100 to 140 mg/cm 2 in less than 1 h. This occurred by oxidation of residual metal in the composite to form Al/Al 2 O 3 deposits on the surface. After the initial formation of the oxidation product, there is little further reaction during up to 300‐h exposures to oxidizing atmospheres. Experimental composite coupons with metal‐free surfaces were resistant to oxidation except for localized events associated with flaws. Small amounts of sodium silicate (2 to 40 mg/cm 2 ) painted on the surfaces produced no corrosive effects on any of the specimens. Dynamic corrosion experiments, in which a continuous mist of sodium silicate was sprayed onto the surfaces, produced corrosion at 1300°C.