Investigation into the Chemical Stability of the TiB2–TiN Eutectic Alloy Fabricated in the Combustion Mode in a Mineral Acid Medium

Abstract

The results of studying the corrosion resistance of the powder of the TiB2–TiN eutectic alloy in a medium of HCl and HNO3 mineral acids are presented. The experiments are performed for samples synthesized in the combustion mode and then powdered in an agate mortar. The particle morphology, size distribution, and specific surface are determined for fabricated powders. The concentrations of acids are varied in a range from 0.2 to 6.0 M and the process temperature is varied from 25 to 80°C in experiments on studying the corrosion resistance. The chemical analysis of studied products of the interaction with the aggressive medium are performed for determining the content of main elements (titanium, boron, and nitrogen) according to procedures developed for refractory compounds. It is shown that the samples possess the largest resistance when interacting with solutions of diluted acids at room temperature, while their resistance decreases with an increase in the acid concentration and/or process temperature. It is found that the interaction with acid is inherent both to the TiB2 phase and for the TiN phase in all cases considered in the work. Herewith, the reaction with the participation of the TiB2 phase was more rapid. For the first time, the depth characteristics of corrosion are determined at room temperature and concentration of acids of 1.0 M, and the alloy corrosion resistance in the HCl and HNO3 medium is evaluated. Based on these data, the alloy was attributed to the group of resistant materials. The corrosion resistance in HCl and HNO3 media was 4 and 5 points, respectively, according to the 10-point scale.