"RIDGE EFFECT" IN OXIDATION KINETICS OF HETERO-MODULUS CERAMICS BASED ON TITANIUM CARBIDE

I. L.SHABALIN
 

Powder Metallurgy - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2008, #01/02
http://www.materials.kiev.ua/article/698

Abstract

Recent studies on oxidation kinetics of the TiC-7 vol.% C (graphite) hetero-modulus ceramics at temperatures of 400–1000 °C and oxygen pressures of 0.13–65 kPa have led to the discovery of a temperature-pressure-dependent phenomenon called “ridge effect”. The oxidation rate of the composite rises rapidly to a maximum at ridge values of oxygen pressure (pо2) or temperature (T), but then it declines with subsequent growth of oxidation parameters. The ridge values mark a change in the prevailing mechanism, as while the ridge parameter traversing the values of apparent activation energy Q or order of reaction m change its sign. The oxidation mechanisms, essentially different within the ranges of parameters, are identified according to the developed ridge-effect model, which can be applied probably to a variety of systems with inorganic compounds.


CHEMICAL PROPERTIES, GRAPHITE, HETERO-MODULUS CERAMICS, HIGH TEMPERATURE MATERIAL, OXIDATION, REFRACTORY COMPOUNDS, THERMOGRAVIMETRIC ANALYSIS, TITANIUM CARBIDE, X-RAY DIFFRACTION, СOMPOSITE