To study the influence of silicon(Si)on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20),NC/CL-20 composite explosives and Si/NC/CL-20 composite explosives were prepared by the electrostatic spraying ...To study the influence of silicon(Si)on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20),NC/CL-20 composite explosives and Si/NC/CL-20 composite explosives were prepared by the electrostatic spraying method.The morphology,structure and thermal decomposition properties of the samples were analyzed using scanning electron microscopy(SEM),X-ray energy spectroscopy(EDS),infrared spectroscopy(FT-IR),and simultaneous thermal analyzer(TG-DSC).Additionally,the combustion process of the samples was tested using a high-speed camera.The results show that the addition of nano-Si contributes to the formation of composite explosives with regular morphology and smaller particle size.The Si/NC/CL-20 composite explosive has better and more uniform sphericity,with an average particle size of 73.4 nm,compared to the NC/CL-20 composite explosive.The Si/NC/CL-20 composite explosive which produced by the electrostatic spraying method,achieves physically uniform distribution of the components including NC,CL-20,Si.The addition of Si promotes the thermal decomposition of CL-20.In comparison to the NC/CL-20 composite explosive,the activation energy of the Si/NC/CL-20 composite explosive decreases by 16.78 kJ/mol,and the self-accelerated decomposition temperature and the critical temperature of thermal explosion decreases by 3.12 K and 2.61 K,respectively.Furthermore,Si/NC/CL-20 composite explosive has shorter ignition delay time and faster combustion rate compared to the NC/CL-20 composite explosive,which shows that Si can improve the combustion performance of CL-20.展开更多
为探究配筋率和复合层厚度对ECC-NC(Engineered Cementitious Composites to Normal Concrete)复合梁抗弯性能的影响,设计了5根ECC-NC复合梁,通过四点弯曲试验,开展了ECC-NC复合梁抗弯性能研究,分析了复合梁破坏模式和裂缝发展规律,探...为探究配筋率和复合层厚度对ECC-NC(Engineered Cementitious Composites to Normal Concrete)复合梁抗弯性能的影响,设计了5根ECC-NC复合梁,通过四点弯曲试验,开展了ECC-NC复合梁抗弯性能研究,分析了复合梁破坏模式和裂缝发展规律,探讨了配筋率和复合层厚度对结构承载能力、韧性及延性的影响。研究结果表明:与普通混凝土梁相比,ECC-NC复合梁破坏模式不同,能有效发挥ECC材料特性,具有较好的抗弯性能;相同配筋率下,受拉区ECC层厚度增加,ECC-NC复合梁的抗弯承载力增强有限,弯剪区裂缝数量增多,延性增强,刚度退化缓慢,最佳复合层厚度为0.3h~0.5h;ECC层具有替代部分纵筋作用,受压与受拉区同时设置ECC层能极大地提高抗弯承载能力、延性及结构韧性;基于响应面法,配筋率对ECC-NC抗弯性能影响最大,最大配筋率与复合层厚度有关,0~0.5h呈负相关,0.5h~h间呈正相关,受压区设置ECC可提高界限配筋率,高配筋率有利于提高抗弯刚度,减缓裂缝扩展;弯曲荷载下,截面符合平截面假定,变形协调;基于条带法,建立了ECC-NC复合梁抗弯承载能力计算方法,与试验结果及已有文献数据校核,平均误差在6%以内,吻合度较高,可为工程应用提供理论支撑。ECC替代普通混凝土,不仅提高了结构抗弯承载力,还延缓了裂缝扩展,改善了复合梁带裂缝工作性能和抗裂性能,且抗弯性能较为优越。展开更多
基金National Natural Science Foundation of China(No.22275150)。
文摘To study the influence of silicon(Si)on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20),NC/CL-20 composite explosives and Si/NC/CL-20 composite explosives were prepared by the electrostatic spraying method.The morphology,structure and thermal decomposition properties of the samples were analyzed using scanning electron microscopy(SEM),X-ray energy spectroscopy(EDS),infrared spectroscopy(FT-IR),and simultaneous thermal analyzer(TG-DSC).Additionally,the combustion process of the samples was tested using a high-speed camera.The results show that the addition of nano-Si contributes to the formation of composite explosives with regular morphology and smaller particle size.The Si/NC/CL-20 composite explosive has better and more uniform sphericity,with an average particle size of 73.4 nm,compared to the NC/CL-20 composite explosive.The Si/NC/CL-20 composite explosive which produced by the electrostatic spraying method,achieves physically uniform distribution of the components including NC,CL-20,Si.The addition of Si promotes the thermal decomposition of CL-20.In comparison to the NC/CL-20 composite explosive,the activation energy of the Si/NC/CL-20 composite explosive decreases by 16.78 kJ/mol,and the self-accelerated decomposition temperature and the critical temperature of thermal explosion decreases by 3.12 K and 2.61 K,respectively.Furthermore,Si/NC/CL-20 composite explosive has shorter ignition delay time and faster combustion rate compared to the NC/CL-20 composite explosive,which shows that Si can improve the combustion performance of CL-20.
文摘为探究配筋率和复合层厚度对ECC-NC(Engineered Cementitious Composites to Normal Concrete)复合梁抗弯性能的影响,设计了5根ECC-NC复合梁,通过四点弯曲试验,开展了ECC-NC复合梁抗弯性能研究,分析了复合梁破坏模式和裂缝发展规律,探讨了配筋率和复合层厚度对结构承载能力、韧性及延性的影响。研究结果表明:与普通混凝土梁相比,ECC-NC复合梁破坏模式不同,能有效发挥ECC材料特性,具有较好的抗弯性能;相同配筋率下,受拉区ECC层厚度增加,ECC-NC复合梁的抗弯承载力增强有限,弯剪区裂缝数量增多,延性增强,刚度退化缓慢,最佳复合层厚度为0.3h~0.5h;ECC层具有替代部分纵筋作用,受压与受拉区同时设置ECC层能极大地提高抗弯承载能力、延性及结构韧性;基于响应面法,配筋率对ECC-NC抗弯性能影响最大,最大配筋率与复合层厚度有关,0~0.5h呈负相关,0.5h~h间呈正相关,受压区设置ECC可提高界限配筋率,高配筋率有利于提高抗弯刚度,减缓裂缝扩展;弯曲荷载下,截面符合平截面假定,变形协调;基于条带法,建立了ECC-NC复合梁抗弯承载能力计算方法,与试验结果及已有文献数据校核,平均误差在6%以内,吻合度较高,可为工程应用提供理论支撑。ECC替代普通混凝土,不仅提高了结构抗弯承载力,还延缓了裂缝扩展,改善了复合梁带裂缝工作性能和抗裂性能,且抗弯性能较为优越。
