Effect of Mechanical Activation of Granulated and Powdered Ni + Al Mixtures on Flame-Propagation Rates and Sample Elongation in Combustion

Resumo

This paper represents the first study of the effect of the duration of mechanical activation (MA) of pre-granulated Ni + Al mixtures with nickel powders of different types on the combustion rate and the change in the sample length after synthesis. The initial mixtures containing different types of nickel had different combustion rates. The mechanical activation leads to an equalization of the combustion rates for powder mixtures at an MA time of 3 to 5 min and for pre-granulated mixtures in the entire MA time interval. The rate of combustion increases with the increased MA time for both powdered and pre-granulated mixtures. An explanation of the observed dependences is proposed. A sudden elongation of the samples during combustion is shown to take place after preliminary granulation of the mixtures. This result is the consequence of a significant increase in gassing due to bundle decomposition at the combustion of granulated mixtures.