The energy release of energetic composites is severely limited by the inert alumina(Al_(2)O_(3))layer on the surface of aluminum(Al).Polytetrafluoroethylene(PTFE)could eliminate Al_(2)O_(3)layer due to its highly elec...The energy release of energetic composites is severely limited by the inert alumina(Al_(2)O_(3))layer on the surface of aluminum(Al).Polytetrafluoroethylene(PTFE)could eliminate Al_(2)O_(3)layer due to its highly electronegativity and oxidability of fluorine.However,adding PTFE particles would weaken interfacial interactions resulted in poor mechanical properties and interfacial exothermic reaction.Herein,a bridging Al-PTFE as fuel and interfacial reinforcing agent was added and used to prepare LLM-105/AlPTFE microspheres,achieving both high energy output and excellent mechanical properties.The energy release and combustion reaction performance of LLM-105/Al-PTFE microspheres are significantly improved due to high reaction heat and increased interfacial reaction area of Al-PTFE.The maximum pressure and pressurization rate of LLM-105/Al-PTFE microspheres are 164.06 kPa and 29.88 kPa/s,respectively,which are 40.11%and 16.67%higher than those of physical mixed samples.Furthermore,the tensile strength and compressive strength of LLM-105/Al-PTFE microspheres are 100.40%and 26.47%higher than those of LLM-105/Al.This work provides a new approach to improve the energy release and mechanical properties for energetic composites.展开更多
After reviewing three different definitions of mode field diameter of single-mode fibers, coupled efficiency calculation methods associated with lateral offset, longitude separation and wavelength, the effects produce...After reviewing three different definitions of mode field diameter of single-mode fibers, coupled efficiency calculation methods associated with lateral offset, longitude separation and wavelength, the effects produced by them, and the influences of splicing defects were discussed in detail. The regularities of the effects were studied according to the first order derivation of couple efficiency formula, and a simplified formula for couple efficiency calculation was presented under the circumstance of slight misalignment, with respect to wavelength, 2, and in a good agreement with the theoretical model. The simplified formula provides a new but simple approach to evaluate wavelength dependent couple efficiency of single-mode fibers. Theoretical analyses and numerical calculations show that, when those defects exist, the wavelength produces additional effects on the couple loss that growth of wavelength causes an increase on the couple efficiency for the lateral offset or longitude separation whereas lessens the couple efficiency due to angular misalignment or mode fields mismatching, and that the wavelength degrades the couple efficiency distinctly when λ≥2.5 μm whereas it distorts the couple slightly in range of λ≤2λ≤2 μm.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.T2222027 and 12202416)。
文摘The energy release of energetic composites is severely limited by the inert alumina(Al_(2)O_(3))layer on the surface of aluminum(Al).Polytetrafluoroethylene(PTFE)could eliminate Al_(2)O_(3)layer due to its highly electronegativity and oxidability of fluorine.However,adding PTFE particles would weaken interfacial interactions resulted in poor mechanical properties and interfacial exothermic reaction.Herein,a bridging Al-PTFE as fuel and interfacial reinforcing agent was added and used to prepare LLM-105/AlPTFE microspheres,achieving both high energy output and excellent mechanical properties.The energy release and combustion reaction performance of LLM-105/Al-PTFE microspheres are significantly improved due to high reaction heat and increased interfacial reaction area of Al-PTFE.The maximum pressure and pressurization rate of LLM-105/Al-PTFE microspheres are 164.06 kPa and 29.88 kPa/s,respectively,which are 40.11%and 16.67%higher than those of physical mixed samples.Furthermore,the tensile strength and compressive strength of LLM-105/Al-PTFE microspheres are 100.40%and 26.47%higher than those of LLM-105/Al.This work provides a new approach to improve the energy release and mechanical properties for energetic composites.
基金Projects（51005074, 91123035） supported by the National Natural Science Foundation of China Project（201021200077） supported by the Frontier Research Program of Central South University, China
文摘After reviewing three different definitions of mode field diameter of single-mode fibers, coupled efficiency calculation methods associated with lateral offset, longitude separation and wavelength, the effects produced by them, and the influences of splicing defects were discussed in detail. The regularities of the effects were studied according to the first order derivation of couple efficiency formula, and a simplified formula for couple efficiency calculation was presented under the circumstance of slight misalignment, with respect to wavelength, 2, and in a good agreement with the theoretical model. The simplified formula provides a new but simple approach to evaluate wavelength dependent couple efficiency of single-mode fibers. Theoretical analyses and numerical calculations show that, when those defects exist, the wavelength produces additional effects on the couple loss that growth of wavelength causes an increase on the couple efficiency for the lateral offset or longitude separation whereas lessens the couple efficiency due to angular misalignment or mode fields mismatching, and that the wavelength degrades the couple efficiency distinctly when λ≥2.5 μm whereas it distorts the couple slightly in range of λ≤2λ≤2 μm.
