Regularities of Combustion of Granulated Mixtures during Single-Stage Synthesis of TiC--CoCrNi Metal Ceramics
B. S. Seplyarsky, R. A. Kochetkov, N. I. Abzalov, T. G. Lisina
Merzhanov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, Russia
Keywords: SHS, titanium carbide, cermets, granules, combustion mode, impurity gas, interphase heat transfer coefficient
Abstract
The combustion behavior of granulated mixtures (100 - X )(Ti + C) + X(Co---Cr---Ni) at X = 0 ÷ 40 wt. %, used for the synthesis of metal ceramics, was studied for the first time. The mixture composition at which the release of impurity gases leads to a transition from the conductive to the convective combustion mode ( X = 20%) was determined by calculation, which made it possible to estimate the impurity hydrogen content in the studied mixtures. For granules of 1.7 mm in size, the filtration of impurity gases through the sample leads to the convective combustion mode at X < 20% and to the conductive one at X > 20%. The conductive combustion mode is realized in all mixtures with granules of 0.6 mm in size. The phase composition of the obtained composite samples is represented by TiC and the fcc phase of the medium-entropy CoCrNi alloy. The interphase heat transfer coefficient in granulated SHS mixtures, calculated using experimental data, is an order of magnitude higher than the theoretical values for the heat transfer coefficient in a porous medium. The proposed synthesis method from granulated mixtures in a flow reactor holds promise for the production of TiC-CoCrNi composite powders used for applying hardening coatings.
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