Effect of the Content of Polyvinyl Butyral on the Synthesis and Phase Composition of Products of Combustion of Ti-Cr-C Granular Mixtures

A study is performed of the effect the content of an organic binder (polyvinyl butyral) in the range x = 0-1.8 wt % has on the rate of combustion and phase composition of products of the synthesis of granular Ti-Cr-C mixtures of different compositions, with and without nickel-containing binder NiCr. For a mixture of 80% (Ti + C)/20% (3Cr + 2C), an extreme increase in the rate of burning is observed when x is raised to 1.8%. Experimental data are explained using a model of the convective combustion regime in which the gaseous decomposition products of polyvinyl butyral ignite the surfaces of granules. The mechanism of the organic binder appearing behind the visible combustion front is described. Necessary and sufficient conditions for obtaining the mode of convective combustion are formulated. According to XRD data, a change in the content of polyvinyl butyral in the initial mixture does not affect the phase composition of the products of the combustion of the considered mixtures. When grinding the products of combustion, raising the amount of polyvinyl butyral increases the content of the fraction with a characteristic particle size of <250 mu m, indicating that such granules are promising for the manufacture of refractory powders.