Study On Spheroidization Of Dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50)

Dihydroxylammonium 5,5'-Bistetrazole-1,1'-diolate(TKX-50)is a novel ion salt explosive with high energy,high density and low sensitivity,it can be widely used in the field of energetic materials.However,the particles of TKX-50 are irregular about the shape and are inhomogeneous in particle size distribution that were obtained from the synthesis,which limits its further application.It is necessary to control the crystal morphology and increase its particle size by crystallization,in this thesis,the crystallization process of TKX-50 was studied to find a better one for preparing TKX-50 with good sphericity.It was determined that the solubility of TKX-50 in pure solvents(dimethyl sulfoxide,formic acid,water,N,N-dimethylformamide,N-methylpyrrolidone)and the mixed solvents(formic acid + water)by using the laser dynamic monitoring technique,solubility curve of TKX-50 in different solvents were drawn according to the results.The solubility data of TKX-50 in pure solvents were fitted by using van't Hoff equation and Apelblat equation,the solubility data of TKX-50 in mixed solvents(formic acid + water)were fitted by using(CNIBS)/ Redlich-Kister equation,the results are in good agreement with the experimental results.Dissolution thermodynamic parameters of TKX-50 in pure solvents were calculated by using the measured solubility data.The morphology of TKX-50 in vacuum was been predicted by using Materials Studio molecular simulation software to find out the stable crystal planes in morphology,they were(100),(020),(011),(11-1),(120),(021),(111),(12-1)and(13-1),respectively.The absolute value of vacuum adhesion of(100)was the smallest and the growth rate was the slowest,it was the most important crystal surface that affects the vacuum crystal morphology of TKX-50.Based on the results of crystallization thermodynamic experiments,the modified adhesion energy of TKX-50 in dimethyl sulfoxide,formic acid and water was calculated for every crystal plane to predicting crystal morphology,which were consistented with the experimental results,the calculation results showed that two solvents of dimethyl sulfoxide and water are beneficial for the crystallization research of TKX-50.Combined with the crystallization thermodynamic experimental data and crystal morphology calculation results,two solvents(water,54% formic acid solution)were selected as suitable solvents which are favorable for the spheroidization of TKX-50 by using cooling crystallization.The effects of crystallization initial temperature,stirring rate,cooling rate,the additive on the morphology of TKX-50 were studied in these two solvent systems.The optimal process for TKX-50 in water and 54% formic acid solution were obtained.