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Biomass-derived anisotropic silicon carbide aerogels with orientation-dependent electromagnetic absorption and high-temperature insulation performance 具有定向电磁吸收和高温绝缘性能的生物质衍生各向异性碳化硅气凝胶

2区工程技术

Defence Technology Pub Date : 2025-11-01 DOI: 10.1016/j.dt.2025.10.014

Yayu Zhao, Limeng Song, Hongshan Wang, Xiaoqin Guo, Hailong Wang, Rui Zhang, Peng Liang, Xiaohan Wang, Ye Yuan, Yanqiu Zhu, Bingbing Fan

{"title":"Biomass-derived anisotropic silicon carbide aerogels with orientation-dependent electromagnetic absorption and high-temperature insulation performance","authors":"Yayu Zhao, Limeng Song, Hongshan Wang, Xiaoqin Guo, Hailong Wang, Rui Zhang, Peng Liang, Xiaohan Wang, Ye Yuan, Yanqiu Zhu, Bingbing Fan","doi":"10.1016/j.dt.2025.10.014","DOIUrl":"https://doi.org/10.1016/j.dt.2025.10.014","url":null,"abstract":"Silicon carbide (SiC) aerogel is a lightweight porous material, which has significant potential in electromagnetic protection due to its high porosity, excellent high-temperature resistance, and superior thermal insulation properties. However, traditional SiC aerogel typically exhibits isotropic structures, making it challenging to achieve environment-responsive orientation control. This research introduces a novel approach by using cornstalk biomass as a carbon source to prepare ultralight (density < 41.8 mg/cm 3 ) anisotropic SiC aerogels through a carbonization-thermal reduction method. The resulting material demonstrates orientation-dependent electromagnetic absorption characteristics: SiC aerogel perpendicular to the growth direction (P–SiC aerogel) achieves optimal electromagnetic wave (EMW) absorption performance with a minimum reflection loss (RL min ) of −51.72 dB and a maximum effective absorption bandwidth (EAB max ) of 6.4 GHz at a thickness of 2.0 mm. In comparison, the growth direction shows an RL min of −23.39 dB. Their multi-level pore structure also provides outstanding thermal insulation and high-temperature stability (above 900 °C). Thus, this strategy, combining biomass-derived materials with an anisotropic structure, offers an expandable, green preparation method for developing environment-adaptive EMW absorption materials. • Biomass-based SiC aerogels are light, porous, heat-stable, and insulate well. • Directional EMW absorption shows structure alignment strongly affects function. • P-SiC aerogel has an RL min of −51.72 dB and an EAB max of 6.4 GHz.","PeriodicalId":10986,"journal":{"name":"Defence Technology","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147332749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Interfacial stability effect of PDA@PVDF dual-coating on CL-20: Synergistically suppressed polymorphic transition and solubility PDA@PVDF双涂层对CL-20界面稳定性的影响：协同抑制多晶转变和溶解度

2区工程技术

Defence Technology Pub Date : 2025-11-01 DOI: 10.1016/j.dt.2025.11.028

Hao Wang, Chengming Li, Enjie Zhang, Yapeng Ou, Xiaoxia Ma

{"title":"Interfacial stability effect of PDA@PVDF dual-coating on CL-20: Synergistically suppressed polymorphic transition and solubility","authors":"Hao Wang, Chengming Li, Enjie Zhang, Yapeng Ou, Xiaoxia Ma","doi":"10.1016/j.dt.2025.11.028","DOIUrl":"https://doi.org/10.1016/j.dt.2025.11.028","url":null,"abstract":"Hexanitrohexaazaisowurtzitane (CL-20) is a high-energy explosive widely used in composite explosives and propellants, but its application is severely limited by thermally induced ε-to-γ polymorphic transition and high solubility in nitrate ester solvents. The transition reduces energy density and increasing sensitivity, and the solubility causes dissolution-recrystallization defects (e.g., voids, compositional inhomogeneities) during long-term storage. To address these issues while preserving its high energetic performance, this study developed a polydopamine@polyvinylidene fluoride (PDA@PVDF) dual-coating strategy, fabricating CL-20 composite particles with a core-shell structure. In-situ X-ray diffraction (XRD) results confirmed that the ε-to-γ phase transition temperature of CL-20 increased from 110 °C (pristine CL-20) to 140 °C. Meanwhile, the CL-20@PDA@9%PVDF sample exhibited the lowest solubility and the best solvent resistance, and the solubility of CL-20 in nitrate ester solvents was drastically reduced from 0.229 g/100 g to 0.026 g/100 g, an 88.6% decrease, effectively enhancing its structural and solvent resistance stability. For energetic performance, when mixed with aluminum powder at a 7:3 mass ratio, the CL-20@PDA@9%PVDF/Al composite achieved a combustion heat of 8275 J/g, 8.7% higher than that of the unmodified Al/CL-20 system (7611 J/g). Combustion pressure tests showed that although the modified system exhibited slightly lower initial peak pressure and pressure rise rate due to dilute CL-20 content from inert coatings, it presented a unique \"delayed enhancement\" effect, with pressure gradually surpassing and ultimately exceeding that of the unmodified system in the middle and late combustion stages, enabling more sustained high-pressure output. This work realizes the synergistic optimization of CL-20’s polymorphic/solvent stability and energetic performance, providing a feasible and scalable approach for the practical application of CL-20 in advanced energetic systems.","PeriodicalId":10986,"journal":{"name":"Defence Technology","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147332140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Non-dimensional analysis on blast wave propagation in foam concrete: Minimum thickness to avoid stress enhancement 泡沫混凝土中爆炸波传播的非尺寸分析：避免应力增强的最小厚度

IF 5.1 2区工程技术

Defence Technology Pub Date : 2023-12-22 DOI: 10.1016/j.dt.2023.12.005

Ya Yang, Xiangzhen Kong, Qin Fang

{"title":"Non-dimensional analysis on blast wave propagation in foam concrete: Minimum thickness to avoid stress enhancement","authors":"Ya Yang, Xiangzhen Kong, Qin Fang","doi":"10.1016/j.dt.2023.12.005","DOIUrl":"https://doi.org/10.1016/j.dt.2023.12.005","url":null,"abstract":"<p>Foam concrete is a prospective material in defense engineering to protect structures due to its high energy absorption capability resulted from the long plateau stage. However, stress enhancement rather than stress mitigation may happen when foam concrete is used as sacrificial claddings placed in the path of an incoming blast load. To investigate this interesting phenomenon, a one-dimensional difference model for blast wave propagation in foam concrete is firstly proposed and numerically solved by improving the second-order Godunov method. The difference model and numerical algorithm are validated against experimental results including both the stress mitigation and the stress enhancement. The difference model is then used to numerically analyze the blast wave propagation and deformation of material in which the effects of blast loads, stress–strain relation and length of foam concrete are considered. In particular, the concept of minimum thickness of foam concrete to avoid stress enhancement is proposed. Finally, non-dimensional analysis on the minimum thickness is conducted and an empirical formula is proposed by curve-fitting the numerical data, which can provide a reference for the application of foam concrete in defense engineering.</p>","PeriodicalId":10986,"journal":{"name":"Defence Technology","volume":"34 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2023-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139029879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0