Yanjing Yang

Metal powder fuels are widely used in various fields such as aerospace, pyrotechnics, damage, and renewable energy. Recently, ramjets have gained significant attention due to their beneficial characteristics, including simple design, light weight, and high thrust-to-weight ratio. These features make them well-suited for aircraft, missiles, and unmanned aerial vehicles. However, there is a conspicuous lack of comprehensive research on modification methods and applicability into the metal powder fuels for ramjets, which creates an obstacle to further and widespread application. Therefore, this paper focuses on modifying metal fuels suitable for powder fuel ramjets. First, the effects of metal features, such as crystallinity, microscopic morphology, and particle size, on the ignition and combustion performance of fuel, flowability, and density are summarized. Second, the research discusses the modified materials and techniques of metal fuels, especially those that can be adapted to powder fuel ramjets, and systematically exhibits the properties of these modified metal fuels in terms of oxidation, ignition, and combustion. Third, the present challenges and prospects of powder fuels ramjets are discussed in detail. The paper serves as a comprehensive reference and guidance for the research on powder fuel ramjets.

Metal organic complexes are regarded as a series of promising combustion catalysts for solid rocket propellants.

Na ₂ B ₂₀ H ₁₈ was explored as a solid electrolyte and showed remarkable electrochemical stability up to 5.1 V vs. Na ⁺ /Na. Na ₂ B ₂₀ H ₁₈ /Na ₂ B ₁₂ H ₁₂ achieved an ionic conductivity of 2.8 × 10 ⁻⁴ S cm ⁻¹ and an electrochemical window beyond 4.8 V.

Novel ferrocene functionalized graphene with different molecular structures were designed, fabricated and characterized via SEM, EDS, FTIR, XPS and RAMAN methods. SEM results show the two-dimensional structure of the as-prepared catalysts, and the active metal Fe is uniformly distributed on the surface of graphene. The FTIR, XPS and RAMAN results confirmed the successful preparation of ferrocene functionalized graphene. The catalytic effects of the as-synthesized catalysts for the thermal decomposition of energetic TKX-50 were monitored by DSC, and the corresponding kinetic parameters were calculated using multi kinetic methods including traditional and nonlinear models. The results showed that the as-prepared ferrocene functionalized graphene can effectively promote the thermal decomposition of TKX-50 with the reduced decomposition peak temperatures and activation energies. In addition, the effects of ferrocene functionalized graphene for TKX-50 decomposition are reflected in both high and low temperature stages, and the effect on the high temperature stage is more significant. The outstanding catalytic activity of ferrocene functionalized graphene is related not only to the good dispersion of active Fe, but also to the enhanced interaction of small molecule products on two-dimensional graphene. Among the ferrocene functionalized graphene studied, G-792-Fe and G-902-Fe exhibit better catalytic effects on the thermal decomposition of TKX-50, which can be used as candidate catalysts for TKX-50-based solid propellants.

The development of highly active electrocatalysts is of great importance toward the practical applications of many meaningful electrocatalytic reactions. In this paper, the synthesis and electrocatalytic properties of a multifunctional ruthenium nickel boride hybrid electrocatalyst are reported for the first time. Compared to pristine nickel boride (Ni‐B) and Ru electrocatalysts, Ru@Ni‐B with trace Ru loading amount of 0.133 mg cm⁻² prepared by a simple wet chemical method, shows remarkably improved activity toward the hydrogen evolution reaction, the oxygen evolution reaction, and the glucose oxidation reaction. The electrolytic cell assembled with Ru@Ni‐B/nickel foam electrode as both cathode and anode can deliver 10 mA cm⁻² at only 1.42 V for alkaline overall water splitting and 1.24 V for glucose electrolysis. It is further found that the synergistic coupling of ruthenium with nickel boride plays an important role in the superior performance of the hybrid electrocatalyst.

Thermal decomposition performance of the insensitive energetic compound 1,1-diamino-2,2-dintroethene (FOX-7) is essential for its application in the field of solid propellant. This study will seek to reveal the catalytic effects of the reduced graphene oxide-bimetallic oxide nanocomposites (rGO-MFe2O4, M=Ni, Co and Zn) on the thermal decomposition, kinetic parameters and pyrolysis mechanism of energetic FOX-7. The results showed that the catalytic activities of the bimetallic iron oxide (NiFe2O4, CoFe2O4 and ZnFe2O4) increased obviously after anchored on the surface of graphene. Particularly, the rGO-NiFe2O4 nanocomposite possessed the best catalytic activity for FOX-7 thermal decomposition. The high thermal decomposition peak temperature (THDP) and the apparent activation energy (Ea) of FOX-7 were decreased by 57.4 °C and 54.27 kJ·mol-1 after mixing with rGO-NiFe2O4 nanocomposite. The excellent catalytic activity of rGO-NiFe2O4 can be attributed to the synergistic interaction between rGO and NiFe2O4, which is beneficial for the reduction of activation energy and high thermal decomposition peak temperature of FOX-7. This study is helpful for the rational design of solid propellant containing FOX-7 and beneficial to understand the thermal decomposition kinetics and mechanism of FOX-7.

The development of novel combustion catalysts is critical for improving combustion performance of high-energy solid propellants. In this work, a nickel-based Schiff base complex, N,N′-bis(salicylidene)ethylenediamino nickel [Ni(Salen)], as a candidate for the combustion catalyst of solid propellants, was synthesized with high purity. The effects of Ni(Salen) on the thermal decomposition reaction of FOX-7, which is closely related to its combustion properties in propellants, were systematically investigated and the corresponding mechanisms were also evaluated through comparison and analysis. Under the action of Ni(Salen), peak temperatures of the two decomposition processes of FOX-7 were reduced from 235.7 and 296.3 °C to 233.7 and 268.7 °C, respectively. The investigations into the mechanisms revealed the interactions between the Schiff base skeleton in Ni(Salen) and FOX-7, which promotes the decomposition of the remaining FOX-7. In addition, it was found that NiO, which was a decomposition product of Ni(Salen), also played an important role in promoting the thermal decomposition of FOX-7.

Modifying the surface properties of energetic materials has theoretical and practical significance in the field of their application. In this paper, irregular cyclotetramethylene tetranitramine (HMX) particles were successfully coated by energetic nitrocellulose (NC), leading to the uniform NC-coated HMX particles. As coating materials, energetic (NC was chosen to decrease the sensitivity and modify the surface property of HMX particles, in order to expand their application furthermore. Scanning electron microscopy, laser particle size analysis, energy dispersive spectrometer, and Fourier-transform infrared (FT-IR) spectra were utilized to investigate the morphology, size, and coating quality of NC-coated HMX particles. These results indicated the effective preparation of composites structure. Moreover, the thermal behaviors of NC-coated HMX particles were investigated by simultaneous thermogravimetric and differential scanning calorimetry analysis, coupled with FT-IR and mass spectroscopy. These results showed that NC did not induce chemical properties change of HMX, only physical hydrogen bond was formed in the coating process. Finally, the friction sensitivity, impact sensitivity, and surface properties NC-coated HMX were investigated, and the results suggested that NC-coated HMX particles had better safety and depicted stronger interaction with the binder matrix than original HMX, owing to the stability of NC on the outer layer.