基于金纳米棒的光热转换材料在激光点火过程中的作用机制研究

Laser ignition is a process in which irradiation makes explosives burning or detonation. Improvements in both safety and reliability in weapon system benefit from this non-contact energy transfer unit. However, The biggest challenge of laser ignition design is lack of appropriate explosives charge with higher mechanical sensitivity and lower ignition thresholds, which prevents the development and application of this advanced technology in the small size weapons, thus decreasing of ignition thresholds withdraws a large number of attentions in energy material area. Recently we have obtained the relationship between aspect ratio and LSPR of gold nanorods whose photothermal conversion efficiency was calculated to be as high as 90.87%. To our best knowledge, the effect and mechanism of photothermal conversion material in laser ignition system still remain to be investigated. In this study, the sub-structure of nanocomposites based on gold nanorods will be designed and prepared to maintain photothermal conversion capacity during laser ignition. Subsequently, GNR-based photothermal conversion material will be doped with explosive FOX-7 and then its ignition thresholds will be inquired. This project is designed to reveal the relationship between photothermal conversion efficiency and laser ignition thresholds, which provides new insights for laser ignition explosives charge with low thresholds.

激光点火技术是通过激光辐照使含能材料发生燃烧/爆炸的先进火工技术，这种非接触式换能单元有利于提高武器使用过程中的安全性与可靠性。目前激光火工系统的发展受限于点火阈值偏高，阻碍了这种先进火工技术在小型化武器系统中的装备与应用，因此降低点火阈值成为激光火工品设计最迫切的需求。鉴于光热转换效率低是炸药难点火的主要原因，申请人前期制备了光热转换效率高达90.87%的金纳米棒，拟研究金纳米棒对激光点火的增敏作用。目前光热转换材料在激光点火过程中的作用及其机制未见文献报道。本项目提出利用光热转换效应降低激光点火阈值的假设，通过对功能材料微结构进行设计优化(金纳米棒长径比与二氧化硅壳层孔结构)保证金纳米棒最大的光吸收系数与光热转换效率；在高能不敏感炸药FOX-7中掺杂这种光热转换材料实现低功率激光点火；最后通过理论计算揭示光热转换材料在激光点火过程中的潜在机制，为激光火工品装药设计提供新思路。

激光点火技术是通过激光辐照使含能材料发生燃烧/爆炸的先进火工技术，这种非接触式换能单元有利于提高武器使用过程中的安全性与可靠性。目前激光火工系统的发展受限于点火阈值偏高，阻碍了这种先进火工技术在小型化武器系统中的装备与应用，因此降低点火阈值成为激光火工品设计最迫切的需求。鉴于光热转换效率低是炸药难点火的主要原因，我们制备了不同长径比与等离激元共振吸收的金纳米棒，并在其表面包覆树枝状介孔二氧化硅来稳定等离激元共振特征与富集TKX-50炸药分子，激光点火实验发现只有等离激元共振吸收位于1064 nm的金纳米可以有效降低TKX-50的激光点火阈值。在该基础上我们又通过硫化亚铜纳米晶在高氯酸铵表面的自组装包覆实现激光点火阈值的降低，结果发现硫化亚铜不仅可以增加复合结构的光热转换效率还可以降低高氯酸铵的热分解温度，一方面增加激光辐照的热量积累另一方面降低燃烧分解的必需温度。最后通过在负氧平衡猛炸药中加入正氧平衡的高氯酸铵，我们发现激光点火的火焰燃烧状态大幅度提升，包括点火延时，火焰燃烧温度等燃烧参数根据氧平衡的不同可被调控。该项目为激光点火装药提供了理论基础与设计思路，具有一定的应用前景。