Contrary to the generally held view that carbides of the transition metals of groups IV and V are inert with respect to water, the authors show on the example of titanium carbide that the carbides are decomposed by water, although the extent of attack is not more than 5–30 atomic layers, i. e., not more than 100–150 A.
The hydrolysis of TiC proceeds according to the reaction: TiC+xH2O → CH4 + TiO2 · xH2O.
Methane is the principal constituent of the gaseous hydrolysis products, and consequently it is possible to regard carbides of the transition metals of groups IV and V as methane derivatives. Hydrogen evolution in both carbides of group V and nonstoichiometric carbides of group IV is believed to take place as a result of the presence of free electrons in the carbides. The complex polymer acid TiO2 · xH2O undergoes dissociation, which becomes intensified in the course of time and results in a rise of hydrogen ion concentration. TiC powder particles are negatively charged. With the results obtained it is possible to choose suitable dispersion media for such powder metallurgical operations as fine milling, slip casting, and others.