Thermochemically bonded ceramic matrix composite coatings

Conference · Fri Dec 31 04:00:00 EST 1993

OSTI ID:143716

Samandi, M; Li, X ^[1]; Ashbolt, L F ^[2]

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1. Univ. of Wollongong, NSW (Australia). Dept. of Materials Engineering
2. C-Ramic Australia, Fairy Meadow, NSW (Australia)

Ceramic matrix composite coatings deposited from aqueous solutions have emerged comparatively recently as a viable technology to confer corrosion, wear and thermal shock resistance to engineering components. This simple and low cost technology is gaining widespread acceptance because it utilizes low curing temperature and provides the ability to coat complex shapes and sizes. In one such coatings, silica and alumina particles are bonded by chromium oxide. The process is based on the chemistry of chromic acid, in particular, the conversion through different oxidation states of chromium trioxide to chromium sesquioxide, as a result of elevated temperature heat treatment. The thermochemical change of chromium is the most fundamental process occurring in the coating and controls the conversion of water soluble binder/densifier to an insoluble ceramic matrix that binds the ceramic particles. In this paper, the authors will review the salient features of the coating technology. Further, the results of an extensive and systematic characterization work will be provided in order to gain an insight into the underlying chemical, physical and metallurgical phenomena occurring in the coating. More specifically, the two fundamental aspects of bonding in the coating, i.e. the coating/substrate adhesion and the particle/binder/particle cohesion, will be thoroughly examined and correlated to the characteristics of ingredient powders. Moreover, the tribological behavior (friction and wear) of coating on mild steel substrate, in sliding contact with single crystal ruby balls will be discussed.

• OSTI ID: 143716
• Report Number(s): CONF-930246--; ISBN 0-87339-251-5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
CHROMIUM OXIDES
COATINGS
COMPOSITE MATERIALS
DEPOSITION
SILICON OXIDES
STEELS
TECHNOLOGY ASSESSMENT