Burning rate catalysts action on the trinitroresorcinol combustion wave parameters

The effect of burning rate catalyst—3% nickel salicylate (NS) with 1% carbon nanotubes (CNT)—on the combustion wave parameters of trinitroresorcinol (TNR) at 2 MPa as well as on the structure and elemental composition of the carbon frame on the surface of quenched TNR samples at 2 and 15 MPa were studied. The catalyst itself increases the burning rate by ∼4.3 times. It is shown that for the sample with NS and CNT, the accumulation of nickel particles formed during the decomposition of the catalyst occurred (∼110 times) at 2 MPa on the carbon frame. The degree of catalyst particles accumulation at 15 MPa is ∼60 times lower than at 2 MPa, so the burning rate increases by only 1.3 times. At 2 MPa the catalyst significantly (by ∼68 K) increases the combustion surface temperature, by ∼2.7 times increases the temperature gradient in the carbon frame zone, and reduces the length of the primary (fizz zone) and secondary flames. As a result, the heat release rate on the frame is 13.5 times higher than on the carbon frame of the sample without a catalyst. For TNR samples the thermal conductivity coefficient, based on the characteristics of the framework obtained, was calculated, and it was shown that the thermal conductivity coefficient of the carbon frame for a sample with NS and CNT is significantly (∼8 times) higher than for a sample without a catalyst. From the calculation of the heat balance of the c-phase at 2 MPa it follows that the combustion leading zone of the sample with a catalyst is the carbon frame, from which ∼98% of the necessary for combustion propagation heat enters the c-phase; for a sample without a catalyst, the heat gain from the gas zone is ∼20%; the leading zone is the reaction layer of the condensed phase. Thus, the mechanism of combustion catalysis of aromatic nitro compounds is the same as for double-base propellants. Two conditions are necessary for combustion catalysis: the formation of a carbon frame on the combustion surface, on which catalyst particles accumulate, and the carbon frame thermal conductivity coefficient must be significantly higher than that of the gas zone above combustion surface of the sample without a catalyst.