Experimental studies of the shock wave properties of two epoxy resins with the same composition but different curing temperatures (160 and 200 °C) at up to 330 GPa pressure have been carried out. Laser interferometry was used to record particle velocity profiles at up to 73 GPa pressure while measuring the shock wave velocity. The release sound velocity was experimentally determined in the 3–73 GPa pressure range. Cumulative explosive shock wave generators were used to study the shock Hugoniot of epoxy resins at pressures above 100 GPa. It was shown that the shock compressibility data of both samples are approximated by a single shock Hugoniot within the experimental error. A kink on Hugoniot recorded close to 25 GPa pressure indicates a chemical decomposition in epoxy resin. Above this kink, a change in the shock wave front structure was recorded. Hugoniots of epoxy resin and unidirectional carbon/epoxy composite were compared at up to 370 GPa pressure.

Polyoxophosphotungstate Li7[γ-PW10O36]·7H2O was synthesized, and its structure was studied by X-ray powder diffraction analysis. Rhombic crystals, space group P21212, a = 12.401(3) Å, b = 18.948(4) Å, c = 9.636(2) Å, V = 2265 Å3, Z = 2, and λ = 0.71069 Å. The complex is thermostable. The interaction of Li7[γ-PW10O36]·7H 2 O with Co(NO3)2 gives a tetranuclear cobalt(II) complex Li7[Co4(H2O)2(γ-PW10O36)2]·36H2O, which is an efficient homogeneous catalyst for the photocatalytic oxidation of water to O2 in artificial photosynthesis. The catalyst turnover number TON = 330; the quantum yield of photogenerated oxygen Φ_O_2 = 0.46.

The results of the measurements of spall strength of polycarbonate at a maximum compression stress of 0.6 GPa in the initial temperature range of 20-185 o C are presented. It has been found a significant decrease in the spall strength when the polycarbonate reached the glass transition temperature. The strain rates in the plastic compression wave are determined depending on the maximum stress under single and stepwise shock compression. The dependences of the shock wave velocity Us --- mass velocity up in the range of maximum shock compression stresses up to 0.8 GPa at different temperatures are constructed. Keywords: Polycarbonate, shock waves, deformation, temperature, spall strength, shock adiabate.

Впервые исследована новая керамика «Идеал», композит алмаз — карбид кремния, полученная в реакционно-диффузионном процессе Тьюринга, что позволяет получать материалы с оптимальным набором физико-механических свойств. Отмечается упруго-хрупкое разрушение, связанное с распространением ударной волны в двухкомпонентной системе. Найден динамический предел упругости, определяемый свойствами карбида кремния, равный 13.4 ГПа. Проведены измерения ее динамического предела упругости и откольной прочности в области упругого деформирования. Определена ударная сжимаемость керамики до давления 625 ГПа.

The Hugoniot elastic limit and spall strength of reactor Mn2-Si steel under shock compression were measured by recording and subsequent analysis of the wave profiles. The temperature-rate dependences of the resistance to high-strain rate and fracture of steel at normal and elevated temperatures are determined. The results of measurements of the strength characteristics of steel under spall are supplemented by a metallographic analysis of the fracture zone and compared with data for 15Kh2NMFA reactor steel and Armco iron. Keywords: ferrite-pearlite steel, shock waves, deformation, temperature, Hugoniot elastic limit, spall strength.

Measurements of the Hugoniot elastic limit and the spall strength of the eutectic alloy Bi --- 56.5 mass%, Pb --- 43.5 mass% were carried out at sample temperatures in the range of 20-109 o C based on registration and analysis of the evolution of shock compression pulses of various amplitudes. It is shown that an increase in the temperature of the samples leads to a decrease in the Hugoniot elastic limit by 25%, and the spall strength of the alloy under study --- by 30%, regardless of the strain rate. An increase in the strain rate by two orders of magnitude leads to an increase in the spall strength by about three times. Approximation power-law dependences of the decay of the elastic precursor on the thickness of the samples and the spall strength on the strain rate before fracture at normal and elevated temperatures are constructed. Keywords: lead-bismuth eutectic alloy, shock waves, deformation, temperature, Hugoniot elastic limit, spall strength.

Measurements of the Hugoniot elastic limit and the spall strength of the eutectic alloy Bi – 56.5 mass%, Pb – mass43.5% were carried out at sample temperatures in the range of 20 0C – 109 0C based on registration and analysis of the evolution of shock compression pulses of various amplitudes. It is shown that an increase in the temperature of the samples leads to a decrease in the Hugoniot elastic limit by 25%, and the spall strength of the alloy under study – by 30%, regardless of the strain rate. An increase in the strain rate by two orders of magnitude leads to an increase in the spall strength by about three times. Approximation power-law dependences of the decay of the elastic precursor on the thickness of the samples and the spall strength on the strain rate before fracture at normal and elevated temperatures are constructed.

The results of the measurements of spall strength of polycarbonate at a maximum compression stress of 0.6 GPa in the initial temperature range of 20-185 0C are presented. It has been found a significant decrease in the spall strength when the polycarbonate reached the glass transition temperature. The strain rates in the plastic compression wave are determined depending on the maximum stress under single and stepwise shock compression. The dependences of the shock wave velocity US - mass velocity up in the range of maximum shock compression stresses up to 0.8 GPa at different temperatures are constructed.

The reaction of photocatalytic reduction of CO2 with water into CO and CH4 in suspensions of the heterojunction semiconductor SiC/ZnO with copper metal Cu (0.5 wt %) deposited on its surface has been studied. The formation of CO and a small amount of CH4 has been established; the methane yield increases fourfold and the CO yield sharply decreases when MgO is additionally deposited on the semiconductor surface. The maximum methane yield is achieved at a MgO content of 1 wt %; however, with a further increase in the amount of MgO, the CH4 yield decreases. The mechanism of CO2 reduction to CO in a two-electron process and to CH4 in an eight-electron process is discussed.

The Hugoniot elastic limit and spall strength were measured for a heat-resistant metal-matrix composite Inconel 625–5%NiTi–TiB2 alloy additive manufactured (AM) by direct laser deposition. The strength characteristics of the alloy were obtained from the analysis of the complete wave profiles recorded with a VISAR laser Doppler velocimeter during shock-wave loading of the samples. The samples were loaded using a PP50 pneumatic gun or ad hoc explosive devices along and across the material deposition direction in order to determine the strength anisotropy of the AM alloy under study. The maximum shock compression pressure was ~7 GPa, and the strain rate under tension before spalling varied in the range of 105–106 s–1. Kinetic dependencies of elastic/plastic transition and critical fracture stresses vs. loading conditions were plotted. It was shown that the Hugoniot elastic limit of the alloy under study decreases as the shock wave travels into the sample, while the spall strength increases as the material’s strain rate increases at the moment of spall fracture. A comparison of the strength characteristics of the Inconel 625–NiTi–TiB2 composite alloy with the original Inconel 625 alloy has shown that an addition of 5% of powder based on NiTi-TiB2 leads to a decrease in its elastic limit and critical fracture stresses upon spalling by more than 10%. The alloy under study demonstrates anisotropy of strength properties relative to the material deposition direction.

Strength measurement results are reported for hot-rolled cast cold-resistant structural alloy steel 09CrNi2MoCu subjected to shock compression up to 15.5 GPa within the strain rate range of 10 5 –10 6 s –1 . Specimens fabricated by direct laser deposition were used to study the effect of the deposition direction and shock compression amplitude on the Hugoniot elastic limit and critical stresses during spall fracture. The strength characteristics were determined by analyzing the full waveform data recorded during loading by a VISAR laser Doppler velocity interferometer. It was found that the spall strength of the cast steel specimens is almost independent of the shock compression pressure, but strongly depends on the strain rate before spalling. The spall strength of the additively manufactured specimens is slightly lower than that of the hot-rolled cast steel specimens and does not depend on the deposition direction. The α ↔ ε phase transformation expected at 13 GPa was not observed in experiments on cast steel 09CrNi2MoCu with the maximum shock compression pressure.

The photocatalytic reduction reactions of CO 2 in aqueous suspensions of titanium dioxide (TiO 2 ) semiconductor with photodeposited Pt and Cu cocatalysts have been studied. It has been found that the composition and amount of CO 2 reduction products significantly depend on the nature of the cocatalyst supported onto TiO 2 . A mechanism for the formation of CO 2 reduction products has been proposed.

For the first time, a new ceramic “Ideal,” a diamond-silicon carbide composite obtained in the reaction-diffusion Turing process, which makes it possible to obtain materials with the optimal set of physical and mechanical properties, is studied. An elastic-brittle fracture related to the propagation of a shock wave in a two-component system is noted. The dynamic elastic limit, determined by the properties of silicon carbide, is found to be 13.4 GPa. Its dynamic elastic limit and spall strength in the region of the elastic deformation are measured. The impact compressibility of ceramics up to a pressure of 625 GPa is determined.

By recording and analyzing complete wave profiles using the VISAR laser interferometer, measurements of the Hugoniot elastic limit and critical fracture stresses were carried out under the spalling conditions of the heat-resistant Inconel 718 alloy, additively manufactured by direct laser deposition, at shockwave loading up to ~6.5 GPa using a light-gas gun. For comparison, similar experiments were performed with the Inconel 718 alloy made by the traditional method of vacuum induction melting. The process of the delay of an elastic compression wave during its propagation through the sample and the dependence of the spall strength on the strain before fracture in the range 105–106 s−1 were investigated. To identify the anisotropy of the strength properties of the material under study, two series of experiments were carried out on loading additively manufactured samples along and perpendicular to the direction of the deposition. The measurements performed showed that the additively manufactured Inconel 718 alloy demonstrates weak anisotropy of strength properties for both the initial and thermal-treated samples. The thermal treatment leads to a noticeable increase in the Hugoniot elastic limit and the spall strength of the samples at low strain rates. For all types of samples, there is an increase in the spall strength with an increase in the strain rate. The spall strength measured for the cast alloy practically coincides with the strength of the as-received additive alloy and is noticeably lower than the strength of the thermal-treated additive alloy over the entire range of the strain rates. The process of the decay of the elastic precursor in the cast alloy occurs much faster than in the additive one, and the minimum values of the Hugoniot elastic limit are measured for thick samples in the cast alloy.

The features of the evolution of the elastic-plastic compression wave in Mo single crystals along the crystallographic plane [100], having a different initial dislocation structure formed by small deformations of varying degrees of static compression at room temperature, have been studied. The analysis of wave profiles recorded using the VISAR laser interferometer in samples of different thicknesses showed a non-monotonic change in the Hugoniot elastic limit depending on the initial dislocation density pre-strain of a single crystal by compression reduces the Hugoniot elastic limit by 3 times. Keywords: Single crystal, small deformations, compression wave evolution, wave profile, VISAR interferometer.

The effect of modest, 0.6% and 5.5%, pre-straining on the impact response of 2 mm thick samples of annealed polycrystalline vanadium of commercial purity was studied in a series of planar impact tests. The loading of the samples by 0.5 mm thick copper impactors having velocities varying between 300 and 610 m/s was accompanied by continuous laser Doppler velocimetry of their rear surface. Based on the recorded velocity histories, the dynamic compressive σY and tensile (spall) σsp strengths and the strength σYsc of vanadium in the shock-compressed state were determined. Adjacent to the impact surface part of the cross sections of the softly recovered samples, the number of twins Ntw per unit area was counted. It was found that the main parameter governing both the strength σY of pristine (in the shock sense) material and that in the shock-compressed state, σYsc, was the initial dislocation density η0. Moreover, the dislocation surplus caused by pre-straining was responsible for complete suppressing of twinning in the 0.6% and 5.5% pre-strained samples. In undeformed vanadium, the twinning was partially suppressed by the presence of impurity atoms which, however, did not affect the twinning stress, which was equal to approximately 0.7 GPa.

The evolution of elastoplastic shock compression and shock release waves in annealed and prestrained (to 0.6 and 5.5%) Armco iron has been studied, and the spall strength of Armco iron has been measured in the pressure range 2–9 GPa at room and elevated (600°C) temperatures. It has been shown that prestraining to 0.6 and 5.5% considerably decreases the dynamic yield strength and slightly increases the spall strength. The dependences of the deformation rate in the plastic shock wave and spall strength on deformation rate in the rarefaction wave have been obtained.

By the example of experimental data on the reflection of an elastic–plastic shock wave from a free surface of a steel or aluminum-alloy plate, the conditions and regularities of the formation of the re-reflected elastic wave are discussed. It is shown that the possibility of its formation, as well as its amplitude and attenuation, is related to the relaxation properties of the material in the state in front of the plastic shock wave.