Plate impact tests at normal and elevated temperatures were conducted to examine the influence of temperature on the dynamic response of 2 aluminum alloys (2024-T4 and 7075-T6) with the temperature range of 300-750 K.The free-surface velocity profiles, including the elastic precursor amplitude, pull-back amplitude and the acceleration of pull-back signals were investigated at different temperatures.Hugoniot elastic limit (HEL) strength and spall strength were calculated using the free surface velocity profiles.Normalized HEL strength and normalized spall strength of 2024-T4 Al and 7075-T6 Al exhibit a similar linear decrease with increasing temperature.A cohesive zone model (CZM) was developed to simulate the spall behavior of aluminum alloys at different pre-heated temperatures.The physical meaning of CZM parameters and how to determine these parameters were discussed.It is found that the predicted free surface velocity profiles under different temperatures are in very good agreement with the experimental data, especially the slope, frequency and decay of the free surface velocity oscillations in the later phases of spalling, which demonstrates that the cohesive law is well applicable to characterize the energy dissipated behavior due to damage evolution.

The effects of temperature on Fe-Mg compositions of garnet in a natural pelitic system were studied experimentally at temperatures from 700 to 780 ℃ and pressures from 2.1 to 2.9 GPa.The garnets formed in the run products were mainly characterized by magnesian and ferreous compositions.The contents of pyrope and almandine are more than 88%(mass fraction) in all the garnet particles analyzed, whereas grossular and spessartine are less than 12%.The concentrations of FeO and MgO of garnet in the run products show significant linear relationship with experimental temperatures but which is not observed with pressures.The results determine the Fe-Mg partition trend with temperature in a natural pelitic rock with complex chemical compositions, which is useful for the identification of metamorphic temperature for eclogite facies rocks with a pelitic protolith composition.

High pressure research is of great importance to the crucial information for many scientific and industrial applications, such as high pressure phase state, synthetic materials and recreating conditions deep inside the earth.Generally, the development of high pressure research is limited by the level of high pressure technology.In this paper, the history of diamond anvil cell (DAC) and Paris-Edinburgh (P-E) press were reviewed firstly.Secondly, the design theory, research, and development of miniature ultra-high pressure devices were studied in detail, including DAC, P-E press, palm cubic-anvil cell (P-CAC), and miniature cubic-anvil cell (M-CAC).Finally, the problems and future development of the science and technologies for the miniature high pressure devices were summarized, which gives a suggestion on the new design of ultra-high pressure apparatus.

A double pulse pneumatic spray system was designed based on the requirements of multiphase explosion expriments.Water was employed to study the spray characteristics of the system.The two phase flow pattern in delivery pipe, the gas-liquid mixing process of spray room, the angle of spray, the Sauter mean diameterD₃₂ and the particle size distribution were measured via digital image processing technology and laser Doppler methods, respectively.The experimental results prove that the annular two-phase flow is the main flow structure in the gas and liquid delivery pipe when the initial pressure is in the range of 0.8-3.3 MPa, the water is between 50-500 mL and the spray duration is fixed at 450 ms.In the meantime, double pulse pneumatic spray was found in gas and liquid mixing process, corresponding to the spray angle between 138°-170° and the mean D₃₂ of 61 μm at 500 ms, respectively.

By using the first principles method based on density functional theory, the physical properties of ferrous-bearing post-perovskite MgSiO₃ at high pressure were calculated.The results show that the high-spin state is conserved for ferrous irons from 0 to 160 GPa.The transition tendency from high-spin state to intermediate-spin or low-spin state at higher pressure was also presented.For those structures containing several Fe²⁺, from the comparison of total enthalpies and the mechanical stability criterion we can conclude that the ferrous irons tend to take the closest positions of Mg²⁺.Moreover, the seismic velocities at 120 GPa (pressure in D^〃 layer) were calculated.The calculations show that both the compressional waves (P-waves) and the shear waves (S-waves) decrease obviously with the increasing concentration of Fe²⁺.Remarkably, the transverse anisotropy of shear wave increases significantly.

This work investigated the structural behavior of PbFe₁₂O₁₉ under high pressure by in situ angular dispersive X-ray diffraction (ADXD) measurements up to 55.3 GPa.The linear incompressibility B_a0=997(38) GPa and B_c0=556(22) GPa, and bulk modulus B₀=254(8) GPa are obtained by fitting the Birch-Murnaghan equation of state with the unit-cell parameters versus pressure below 29.2 GPa.The anisotropic incompressibility can be attributed to the layered-stacking structure of PbFe₁₂O₁₉; the relative stiffness of PbFe₁₂O₁₉ can be ascribed to the dense atomic arrangement and the decreasing c/2a ratio.In addition, the ambient structure evolves to another structure above 42.7 GPa under compression and recovers below 32.3 GPa during releasing of pressure.

A vertical shock tube of 200 mm in inner diameter and 5 400 mm in height was used to study the deflagration and detonation parameters of ethane-air mixtures under a high initial pressure(0.25 MPa).The gas mixtures flow into the shock tube through two inlets at two ends of the shock tube instantaneously, the experiments of 3 concentrations of mixtures and 5 diffusion times were carried out with high initiation energy.The experimental results show:when the diffusion time exceeds 1 h, the trends of the deflagration-detonation parameters of C₂H₄-Air for 3 concentration are similar; 4.00%(volume fraction)C₂H₄-Air can't meet the detonation criteria under the experiment condition; 6.67%C₂H₄-Air can be ignited at 5 diffusion times, the detonation pressure and velocity separately are 4.24 MPa and 1 719 m/s when the diffusion time is 1 h; 8.89% C₂H₄-Air deflagrates when the diffusion time is 0.08 h, the detonation pressure and velocity separately are 4.31 MPa and 1 813 m/s when the diffusion time is 1 h; We seized the detonation cell size of 6.67%, 8.89%C₂H₄-Air by smoked foil, the width separately are 8.22 and 14.15 mm, L/λ separately are 1.44 and 1.57.

The particle and stability properties of phosphatides dispersions affected by pulsed electric field, ultrasound, microfluid were studied using dynamic light scattering techniques.Results indicate that the average diameter of phosphatides particles decrease from 594.4 nm to 259.2, 88.7, 37.8 nm after being treated by 60 kV/cm pulsed electric field, 500 W ultrasound and 130 MPa microfluid, respectively.As for the stability of the treated phosphatides dispersion, it is demonstrated that the ultrasound treated sample is the most stable one, then following microfluid and pulsed electric field treated samples.

Through the plane-wave method in the framework of density functional theory in combination with the quasi-harmonic approximation, the mechanical stability, phase boundary, electronic structures and elastic properties of β-, w- and γ-Ge₃N₄ are investigated at high temperatures and pressures.The γ phase, which belongs to super-hard material, has the maximum rigidity and shear stress resistance.The β phase has the minimum bulk modulus, Young's modulus and G/B ratio.The β phase has better ductility and tenacity than the other two phases.β- and w-Ge₃N₄ belong to ductile materials while the γ phase shows a brittle manner.When the pressure exceeds 30 GPa, the γ phase belongs to ductile materials too.β-, w- and γ-Ge₃N₄ are typical semi-conductors, the bonding interactions are mainly contributed by the Ni-2p, Ge-4s and 4p bands.The β, w and γ phases belong to Γ-A, Γ-N indirect band gap and direct band gap semiconductors, respectively.The β→w phase transition is sensitive to pressure.The w→γ phase transition is accompanied by the shrinkage of volume.Meanwhile, the phase boundaries of β→w→γ transitions are also successfully obtained.

Testing non-metallic materials are of great value to mining industry.The MIE (Minimum Ignition Energy) characterize the danger of a kind of combustible gas and its ignition.We calculated the MIE of the ignition system which can be used to test the antistatic property of the mine using materials.According to the structure of the antistatic property testing system, a method to calculate the electromagnetic energy of the ignition system was presented, and according to the MIE and electromagnetic energy before ignition, the quantity of triboelectric charge was obtained, as well as the threshold value of ignition energy coupling coefficient and the threshold value of quantity of triboelectric charge.The results shows that the threshold value of ignition energy coupling coefficient decreases as voltage grows, grows as the electrode distance gets wider.Familiar to the variation of ignition energy coupling coefficient, the threshold value of quantity of triboelectric charge grows as the electrode distance gets wider.For the system described in this paper, the threshold increases from 0.416 3 to 0.769 1 when the distance increases from 1 mm to 5 mm.This study puts forward to the test way to non-metallic materials and provides reference to setting safty standard concerns.