| Laser ignition technology is a new type of safe and reliable ignition technology.Compared with the conventional ignition method,laser ignition can effectively avoid the interference of static electricity,radio frequency and stray current,and improve the safety of laser pyrotechnics in storage,transportation and application.Laser ignition technology has been widely concerned by researchers.However,at present,the research is relatively simple on ignition agents and has not yet formed a system.In this paper,the heat-resistant explosive potassium picrate(KP),was used as raw material,its photosensitive was improved by adding nano-photosensitizers such as Carbon black,carbon nanotubes,graphite,graphene,etc.which effectively reduced the KP laser ignition delay and minimum ignition energy.Using a low-power diode laser as the ignition source,the deflagration-to-detonation process of the chemical was realized under confined conditions.The main research contents are as follows:(1)The heat-resistant explosive,potassium picrate,is used as the main part of laser ignition explosive,and nano-carbon material with good conductivity,thermal conductivity and light absorption is used as an additive.The laser ignition agent with excellent photosensitivity and mechanical properties was prepared by a direct method and a mechanical mixing method,and the fluororubber F2602 was used as a binder to coat and granulate the sample to meet the need of pressure molding.(2)Samples were characterized by DTA,SEM,and TEM.The DTA analysis shows that the decomposition peak of KP of the pure material is 347°C.After addition of carbon materials such as carbon nanotubes,graphite,carbon black,and graphene oxide,the decomposition peak of KP did not change significantly and did not affect its heat resistance.It can be seen from SEM and TEM tests that the KP crystals are uniform in size with short rod-shaped,about 10~20 μm,with no obvious crystal defects.The additives are evenly distributed on the surface of the KP crystals.For samples added with carbon nanotubes,some discontinuous crystals were crystallized on the inner wall of the carbon tube.(3)The mechanical and thermal properties were tested by drop weight impact and pendulum friction devices.The results showed that the impact sensitivity of the sample increased by 3%-7%,and the firing rate of friction sensitivity decreased from 100% to 4%,indicating that the safety of KP has been greatly improved.The mass fraction reduction of the sample is less than 0.01% within the allowable range,at a constant temperature of 75°C for 48 h,and there is no thermal decomposition phenomenon,indicating that the sample has good thermal stability.(4)The sample is subjected to ignition tests under open conditions using a low-power continuous diode laser.The effects of carbon content,additive type,laser energy size,and binder on KP ignition performance were studied.The results show that under the same test conditions,the smaller the crystal size,the shorter the ignition delay period.The ignition delay time is gradually reduced with the increase of laser power density.With the same laser energy density conditions,1%~3% of additives can significantly reduce the KP ignition delay time as well as the minimum ignition energy.In general,the laser ignition performance of the samples added carbon nanotubes is the best,the graphene oxide is the second one and the carbon black material is the worst one.(5)According to the mechanism of explosive deflagration to detonation(DDT),a laser ignition device was designed and successfully output detonation under the action of low-power laser,which indicated that the igniter can also be used as a primer charge. |
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