The Aqueous Corrosion Response of Ti(C,N), TiC and WC Based Ceramic-Metal Composites
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The aqueous corrosion behavior of TiC and Ti(C,N) based cermet materials has been investigated in the current work, using a variety of Ni3Al-based intermetallic alloys as the binder phase. Cermets were prepared using a reaction-sintering route, with either 20 or 30 vol. % of the intermetallic binder, achieving densities in excess of 98% of theoretical. Furthermore, the individual TiC and Ti(C,N) ceramic phases, and the stoichiometric Ni3Al intermetallic phase have been prepared using spark plasma sintering (SPS), in order to analyze the electrochemical characteristics of the parent compositions. Measurement of the open circuit potential was used to determine the equilibrium electrochemical potential. The potentiodynamic and cyclic polarization responses of the cermets and single-phase constituent materials have been examined, with Tafel extrapolation used to determine the rate of corrosion for each composition. Inductively coupled plasma optical emission spectrometry was then applied to analyze the post-test corrosion solutions. It was demonstrated that selective attack of the binder occurs, and the extent of corrosion and primary mechanism depends on the amount of nitrogen in alloy composition, and the intermetallic binder composition and volume fraction.