The Design Of Ultraviolet Curing Explosive Ink And The Study Of 3D Direct Ink Writing

MEMS（Micro-Electromechanical）pyrotechnics is the main direction for the development of advanced pyrotechnics in the future,and it is also an inevitable choice for the development of micro-initiation sequences.Explosive ink direct writing technology has the characteristics of safety,reliability,precise charging and patterning.It has become one of the most effective charging method for MEMS pyrotechnics.Aiming at the slow curing speed of the traditional explosive ink,this paper introduces a new UV-curable material which instead of the traditional bonding system into the explosive ink formula,and designs a new type of fast-curable explosive ink formula.The device was charged and cured by the explosive ink direct writing technology and UV-curing technology.The curing mechanism of explosive ink was discussed,and the microstructure,safety performance and detonation transferability of the samples were tested and analyzed.The details are as follows:First,the raw CL-20 was refined by mechanical ball grinding method and the microstructure of the sub-micro-CL-20 sample was characterized.The UV-curing binder system was composed of two-functionality polyurethane acrylate,2,4,6-trimethylbenzoyl-diphenylphosphine oxide（TPO）and ethanol.And the content of each component of this binder system was optimized by controlling variable method.The rheological properties of explosive ink formula with different CL-20 contents were tested by using a rheometer.The results showed that the refined submicron CL-20 has a spherical appearance,a uniform particle size.After optimized the UV-curing binder system,the distribution ratio of each group was:9.05%wt PUA,0.47%wt TPO and 90.48%wt ethanol.When the CL-20 content was 90%wt,the non-Newton index of the CL-20 based UV-curing explosive ink was the highest,which can meet the requirements of the direct ink writing and curing process.Then,the microstructure and crystal form of the explosive ink samples were characterized by scanning electron microscope（SEM）and X-ray diffractometer（XRD）.The change of hardness and curing rate of the samples were determined by a pencil hardness tester.And the thermal decomposition performance,impact sensitivity and friction sensitivity of the sample were tested and analyzed.The results show that the surface of the sample was smooth,the distribution of CL-20 and the binder was uniform,and the crystal type of CL-20 in the samples was same as the raw CL-20,it was stillε.The curing time of UV-curing explosive ink was less than 10 minutes,and it has fast curing speed.Compared with the sub-micro-CL-20,the peak of decomposition temperature of the UV-curing explosive ink sample was about the same,the thermal decomposition activation energy（）of the sample was about 201.15kJ·mol^-1,the H₅₀ value of the sample was 40.6 cm.Finally,the detonation critical thickness,limit thickness,and detonation velocity of UV-curing CL-20 based explosive ink forming samples were tested and analyzed,and the ability of initiating the next-stage explosive charge and continuous corners was preliminary studied.The results show that the detonation critical thickness of the sample was 0.078 mm（the charge width is 1 mm）,the limit thickness was less than 1mm（the charge width is 1 mm）,and the detonation velocity was 7357 m·s^-1(the charge width is 1mm and the samples density is1.6745 g·cm^-3).In addition,the sample can successfully be initiated,stably detonate the lower stage charge（PBXN-5）,and cannot successfully detonate the lower stage charge（PBXN-7）.At the same time,the detonation wave of the sample can be successfully propagated in the micro-size charge circuit with multiple 90°corners.