Oxidation and corrosion of SiC{sub (particulate)}/Al/Al{sub 2}O{sub 3} composites in sodium silicate at elevated temperatures
- Pennsylvania State Univ., University Park, PA (United States). Center for Advanced Materials
- Univ. of Illinois, Chicago, IL (United States). Dept. of Civil and Materials Engineering
Ceramic-matrix composites (CMCs) fabricated by the directed metal oxidation process (Dimox{trademark}) 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 1,000--1,300 C. The untreated CMCs experienced rapid oxidation in air leading to mass increases of 100 to 140 mg/cm{sup 2} in less than 1 h. This occurred by oxidation of residual metal in the composite to form Al/Al{sub 2}O{sub 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{sup 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 1,300 C.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 282214
- Journal Information:
- Journal of the American Ceramic Society, Vol. 79, Issue 7; Other Information: PBD: Jul 1996
- Country of Publication:
- United States
- Language:
- English
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