Preparation Of Submicron CL-20 And Its Application In The Solid Propellant

Development of the high-energy and insensitive propellant is one of the important direction of solid propellant. Employment of high energy density compounds, such as CL-20, is an effective method to achieve high-energy propellant. However, CL-20 has failed to see widespread application in the high-energy and insensitive propellant due to its high sensitivity. It would therefore be particularly important to promote development of the high-energy and insensitive propellant by obtain insensitive CL-20 particles. In recent years, lots of researches indicated that preparing ultrafine energetic material particles could considerably reduce sensitivity and improve safety of the energetic materials. Therefore, many different methods to prepare ultrafine CL-20 particles have been reported, and each has both strengths and weaknesses. But massive preparation of ultrafine CL-20 particles has been an important subject research for achieving application of the reduced-sensitivity CL-20. For this purpose, mechanical milling method was employed to safely and massively prepare submicron CL-20 particles in this study, and a tentative exploration about an application of the CL-20 particles with submicron size in composite solid propellant was carried out. The details as follows:Firstly,500g submicron CL-20 particles was prepared safely and massively by mechanical milling method. The laser granularity measurement and Scanning Electron Microscopy (SEM) were used to characterize particle size distribution and morphology of the submicron CL-20, and effect of drying process on submicron CL-20 particles size was studied. The polymorph and purity for submicron CL-20 were characterized by Raman, FT-IR, XRD and HPLC, respectively. The results show that submicron CL-20 particles are pseudo-spheres with an average particle size (d50) of 200 nm and narrow size distribution. The polymorph for the submicron CL-20 with high purity is consistent with the raw ε-CL-20.Secondly, the TG/DSC simultaneous thermal analyzer was used to study the thermal decomposition of the CL-20. The impact sensitivity, friction sensitivity and shock sensitivity for both samples were studied. The results indicate that the thermal stability of the CL-20 after to be submicron size is unchanged basically, and the impact, friction and shock sensitivities of the submicron CL-20 are considerably reduced by 116.2%,22% and 53.1%, respectively. That imply the obvious reduction of the CL-20 sensitivity, and promises strong potential for application of the submicron CL-20 as a modern energetic material.At last, there was a tentative exploration about an application of the CL-20 particles with submicron size in HTPB composite solid propellant, and thermal performance and power properties of the submicron CL-20/HTPB propellant were studied. The results show that thermal stability of the CL-20/HTPB propellant decreases slightly as the submicron CL-20 content increases, however, the maximum flame temperature and burning rate of the composite solid propellant both increases as the submicron CL-20 content increases.