一种高精度爆速测量方法

为精确测量炸药拟定态爆速,设计了尖形探针和相应的实验测量方法,测量了有机玻璃、不锈钢、铝合金约束下片状TATB为基钝感炸药的拟定态爆速,结果为(7.527±0.017)km.s-1。表明:采用尖形电探针测量钝感炸药爆速的不确定度为19 m.s-1,相对不确定度为0.25%,与洛斯阿拉莫斯国家实验室(LANL)精密爆轰物理实验结果相当,为精密爆轰物理实验提供了一种新的爆速测量方法。     

Molecular Dynamic Simulation for HMX/NTO Supramolecular Explosive

Based on the crystal engineering, six models of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX)/3-nitro-1,2,4-triazol-5-one(NTO) supramolecular explosive were designed. The probable formation of HMX/NTO supramolecular explosive was investigated by the molecular dynamic (MD) method. Interaction between oxygen atoms in HMX and hydrogen atoms in NTO or between hydrogen atoms in HMX and oxygen atoms in NTO were studied by the radial distribution function (RDF). It shows that there are strong hydrogen bonds and Van Der Waals forces between HMX and NTO, in which the hydrogen bonds between oxygen atoms in the NTO and hydrogen atoms in HMX are the main host-guest interactions. The distributions of bond length, bond angle and dihedral angle were simulated by MD. It shows that the structure of HMX is seriously distorted. The binding energies and X-ray powder diffraction (XRD) patterns were calculated on the basis of the final HMX/NTO supramolecular structures. The results show that the binding energies of six supramolecular models are E binding (1 1 1-) >E binding (1 0 0)>E binding (0 2 0)>E binding (random)>E binding (1 0 2-)>Ebinding (0 1 1), and the XRD patterns of six supramolecular models are quite different from pure HMX or NTO. Based on the investigation for growth morphology, binding energies and RDF, the model of HMX supercell substituted by NTO along the (1 1 1-) surface of HMX is easier to form.     

Response of structure and mechanical properties of high entropy pyrochlore to heavy ion irradiation

Material with superior damage tolerance, chemical durability, and structure stability is of increasing interest in high-level radioactive waste management and structural components for advanced nuclear systems. In this paper, high-entropy (La_0.2Ce_0.2Nd_0.2Sm_0.2Gd_0.2)₂Zr₂O₇ with pyrochlore-type structure was synthesized through conventional solid-state method. The as-synthesized high-entropy oxide maintained crystalline after being irradiated by using Au³⁺ with 9.0 MeV energy at the fluence of 4.5 × 10¹⁵ ions·cm^-2, indicating its high tolerance to heavy-ion irradiation. The irradiation-induced order-disorder transition from pyrochlore structure to defective fluorite structure occurred in high-entropy (La_0.2Ce_0.2Nd_0.2Sm_0.2Gd_0.2)₂Zr₂O₇. After irradiation, no irradiation-induced segregation was observed at grain boundary. Moreover, the mechanical properties of high-entropy pyrochlore were improved. The heavy-ion irradiation resistance mechanisms of high-entropy pyrochlore were discussed in detail. Our work identified high-entropy (La_0.2Ce_0.2Nd_0.2Sm_0.2Gd_0.2)₂Zr₂O₇ can be a promising candidate for immobilization of high-level radioactive waste as well as advanced nuclear reactor system from the perspective of irradiation resistance.     

Fabrication of carbon-coated boron carbide particle and its role in the reaction bonding of boron carbide by silicon infiltration

To tackle the dissolution problem of boron carbide particles in silicon infiltration process, carbon-coated boron carbide particles were fabricated for the preparation of the reaction-bonded boron carbide composites. The carbon coating can effectively protect the boron carbide from reacting with liquid Si and their dissolution, thus maintaining the irregular shape of boron carbide particles and preventing the growth of boron carbide particles and reaction formed SiC regions. Furthermore, the nano-SiC particles, originated from the reaction of the carbon coating and the infiltrated Si, uniformly coated on the surfaces of boron carbide particles, thus forming a ceramic skeleton of the nano-SiC particles-coated and -bonded boron carbide particles. The Vickers hardness, flexural strength and fracture toughness of the composites can be increased by 26 %, 45 %, and 37 % respectively, by using carbon-coated boron carbide particles as raw materials.     

Enhanced near-infrared transmission of ZnO-doped Y2O3–MgO nanocomposites with reduced light scattering due to decreased refractive index difference

Y₂O₃–MgO nanocomposites have received attention owing to their high optical and mechanical properties. However, the inevitable light scattering stemming from the refractive index difference between the two phases limits their applications in the near-infrared region. In this study, the grain boundary light scattering was reduced by doping ZnO into MgO. Y₂O₃–Mg_1?xZn_xO nanocomposites were fabricated by hot-press sintered nanopowders synthesized via the sol-gel combustion process. The addition of ZnO reduced the sintering temperature by almost 300 °C and reduced the average grain size by more than 50 nm. Transmittance of 75%–85% was maintained for all samples in the wavelength range of 2–6 µm. The near-infrared cut-on wavelength shifted from 1222 to 843 nm when the ZnO concentration was up to 25 mol%. This work demonstrates the potential of ZnO-doped Y₂O₃–MgO nanocomposites as infrared transparent ceramics over a wide infrared transmission range.     

二氧化硅气凝胶隔热涂料的性能评价

通过控制合适的条件,将SiO2气凝胶微球加入到纯丙乳液中,混合其它助剂,制成SiO2气凝胶隔热涂料;并运用相关国家标准提供的方法对其进行性能检测。实验结果表明,它具有较好的液态性能、颜色和外观、硬度和附着力、耐水耐热性和隔热性;在实验探索中,还建立了一套针对于SiO2气凝胶隔热涂料的性能评价体系。     

Microwave Sintering of Ti3Si(Al)C2 Ceramic

In this work, microwave sintering (MWS) method was successfully applied for fabrication of dense layered ternary Ti₃Si(Al)C₂ ceramic. Compared to conventional pressureless approaches, MWS could significantly decrease preparation temperature from 1600°C to 1400°C. The activation energy of the MWS process was estimated as 233 ± 18 kJ/mol, which was much lower than those in previous sintering techniques. The low sintering temperature likely originates from the low activation energy during MWS process. Such low temperature do not only make the as‐received Ti₃Si(Al)C₂ ceramic much smaller grain size and better mechanical properties, but also indicate higher energy converting efficiency during the sintering processes. Wide application of MWS techniques in MAX phases is expected to promote the practical applications of these materials and contribute to the energy saving during sintering process.     

Low-temperature reactive hot-pressing of cerium-doped titanate composite ceramics and their aqueous stability

Reactive hot-pressing was scarcely applied to fabricate titanate ceramic waste forms designed for immobilizing high-level radioactive waste (HLW). However, compared with non-reactive processes, there is an advantage of producing high-density ceramics at reduced temperatures by reactive hot-pressing. Ce^IV-doped titanate composite ceramics with relative densities in excess of 99% were prepared by reactive hot-pressing at temperature as low as 1150 °C and pressure of 30 MPa for 1–4 h. The results show that low-temperature densification of the composite ceramics might be attributed to the plastic deformation under hot-pressing condition. In addition, aqueous stability testing was carried out using the standard MCC-1 static leach test method. The results demonstrate that the normalized elemental leach rate of Ca, Ce and Zr were fairly constant in a low value below 5 × 10⁻² g m⁻² d⁻¹, 7 × 10⁻⁶ g m⁻² d⁻¹ and 6 × 10⁻⁶ g m⁻² d⁻¹ after 21 d.     

Electrically conductive aluminosilicate/graphene nanocomposite

Highly electrically conductive ceramic material based on aluminosilicate/graphene nanocomposite has been prepared by high pressure (400 MPa) compaction of montmorillonite intercalated with polyaniline followed with the high temperature (1400 °C) treatment in argon atmosphere. Tablets pressed from polyaniline/montmorillonite intercalate exhibits strong texture due to the disk-shaped montmorillonite particles and, consequently, the high anisotropy in conductivity. The high temperature induced phase transformation of montmorillonite into cristobalite and mullite preserved the aluminosilicate layered structure and created good conditions for formation of graphene sheets from polyaniline layers intercalated in montmorillonite. Therefore, the texture and anisotropy in conductivity remain preserved in resulting aluminosilicate/graphene tablets, while the in-plane conductivity in aluminosilicate/graphene tablets is 23,000× higher than the conductivity of uncalcined polyaniline/montmorillonite tablets. Simple fabrication method of aluminosilicate/graphene tablets is very promising for the manufacturing of the electrically conductive and tough ceramic material, which can be exposed to corrosive environment as well as to high temperatures.     

环氧树脂灌封胶增韧研究

研究了橡胶、纳米填料对环氧树脂灌封胶的增韧作用。通过加入端羟基丁腈橡胶(HTBN)、聚硫橡胶、纳米氧化铝等,使灌封胶冲击、压缩强度得到了较大提高。