Combustion macrokinetics of granulated $(\mathrm{Ti}+\mathrm{C})-\mathrm{Ni}$ mixtures. Impact of grain size

This paper describes the combustion of $90\%(\mathrm{Ti}+\mathrm{C})+10\%\mathrm{Ni}$ and $80\%(\mathrm{Ti}+\mathrm{C})+20\%\mathrm{Ni}$ granular mixtures with a binder (polyvinyl butyral) content of the order of $1\%$, used to obtain composite materials. Experimental data and calculations show that combustion waves in grains of fractions of $0.4$–$0.8$, $0.8$–$1.2$, $1.4$–$2$, and $0.6$–$1.6$ mm propagate in the conductive mode. The micro- and macroscopic characteristics of combustion (namely the combustion transfer time from one granule to another and the burning rate of the granule substance) are calculated on the basis of the experimental burning rate of granular mixtures from granules of different fractions for the first time. The combustion transfer time from one granule to another for mixtures with $10$ and $20\%$ $\mathrm{Ni}$ turns out to be the same for all fractions: approximately $0.006$ s. Regardless of the granule size, X-ray diffraction patterns of combustion products contain only $\mathrm{Ti}\mathrm{C}$ and $\mathrm{Ni}$ phases. Brittle agglomerates easily crushed under laboratory conditions are obtained as a result of the synthesis. The resulting data indicate the possibility of possibility of safe scaling of the process of obtaining $(\mathrm{Ti}+\mathrm{C})+x\mathrm{Ni}$ cermets with a $\mathrm{Ni}$ content of $10$ and $20\%$ in the combustion mode from a granular charge with granule sizes up to $1.7$ mm.