An experiment on dynamic loading at high strain rate was conducted for T4 deformed ZK60 magnesium alloy by means of split Hopkinson pressure bar (SHPB). The experimental results show that the flow stresses of the ZK60 alloy samples increase with the increasing of strain rate. Observation of transmission electron microscopy results indicate that a large number of second phases precipitated in the alloy after dynamic loading. The hardness measurement results show that the hardness of material is elevated from 64.40HV to 93.05HV after dynamic loading at 3 000 s^-1. High-density dislocation is generated within the ZK60 alloy and numerous reinforcing phases (β′₁ and β′₂) precipitated in the matrix during deformation.

Interrupted quenching experiments were conducted to investigate the hardness (HV) and unit initiation energy (UIE) of 7N65 alloy samples at various temperatures with different hold time, and the relative TTP-HV and TTP-UIE contour diagrams were also plotted. The precipitation behavior of second phases at various temperatures was characterized by adopting scanning electron microscope and transmission electron microscope. The findings reveal that S-phase (Al₂CuMg) is the dominant grain boundary precipitate after the alloy is held at a temperature between 390 ℃and 450 ℃, and increases in grain size and numbers as hold time is prolonged. Thus the alloy has less fracture toughness and is prone to fragile fracture along with the broken grains. When the alloy sample is held at a temperature between 250 ℃and 390 ℃, precipitates at grain boundaries are predominated by η-phase (MgZn₂), which increases in the numbers and grain size as hold time is prolonged, leading to lower strength of inner grain, smaller difference in strength between inner grains and grain boundaries. Thus, the alloy has higher fracture toughness and is more prone to ductile fracture with more transgranular dimples.

Hollow microsphere BiOBr photocatalyst was synthesized using hydrothermal method. BiOBr photocatalyst doped with different content of Fe were prepared by regulating Fe³⁺/Bi³⁺molar ratio. The crystal structure, morphology, optical and electrochemical properties of Fe-doped BiOBr photocatalyst were characterized respectively. With organic dye Congo red (CR) as the pollutant, its photocatalysis was evaluated by testing the degradation effect of the photocatalyst on the pollutant under visible light irradiation. The results showed that the photocatalytic material with 7% Fe doping exhibited the optimal photocatalytic performance. The degradation efficiency of CR within 180 min of irradiation with 5 W light-emitting diode (LED) was 89.66%, which was much higher than that of undoped BiOBr (62.82%). It is found that the enhanced photocatalytic performance of Fe-doped BiOBr is attributed to the enhanced light absorption and the efficient transfer and separation of photogenerated carriers.

316L stainless steel coatings were prepared on the surface of 304 stainless steel by using laser cladding at different scanning speed, and then metallographic microscopy, X-ray diffractometer, scanning electron microscopy and microhardness tester were adopted respectively to investigate the macroscopic morphology, phase composition, microscopic structure and microhardness for the coatings. The results showed that the 316L coating had a single-phase austenitic structure, and as the scanning speed increased, the grain size of the coating became smaller due to the reduction in the laser power density and heat input, and an increase in the cooling speed. It is found that the microhardness of the coatings is positively correlated with scanning speed, and the 316L coatings prepared by laser cladding at a scanning speed of 1 400 mm/min presents the highest microhardness of about 275HV_0.3. The improvement of the microhardness of the coating is ascribed to the effect of solid solution strengthening caused by lattice distortion combined with the effect of fine crystal strengthening. The wear test showed that the average friction coefficient of 316L coatings was significantly lower than that of 304 stainless steel substrate. And the 316L coating prepared by laser cladding at 1 400 mm/min has a friction coefficient of 0.424 and wear rate of 2.29 × 10^-6 mm³/(N·m), and is prone to abrasive wear.

V₂O₅ thin films were prepared on FTO conductive glass substrates by electrodeposition-assisted sol-gel technique, and effects of precursor concentration on the structure, morphology and optical properties of V₂O₅ thin films were investigated. The results of XRD and XPS show that the prepared films are all V₂O₅ films, and the diffraction peaks in the XRD pattern are sharp, indicating that the films have good crystallinity. No other impurity peaks appeared in the XRD and XPS spectra, which indicated that the prepared V₂O₅ film had high purity. The results of SEM show that the surface of V₂O₅ film is uniform and compact, and mainly consists of spaced small particles. UV/VIS/NIR test results indicate that the transmittance of V₂O₅ thin film is greatly affected by the concentration of precursor, and reaches the highest of 80.18% when the concentration of precursor is 1∶100. The infrared spectrum test result shows that the infrared transmittance of V₂O₅ thin film decreases from 89.5% to 20.5%, as its semiconductor state at low temperature changes to metal state at high temperature.

Fe-Cr-B based wear-resistant coating was prepared on the surface of 45 steel by ultra-high-speed laser cladding. The effects of laser power, scanning speed and powder feeding speed on the aspect ratio and crack of single pass cladding layer were studied by orthogonal experimental method, and the effects of overlap rates on the surface quality of cladded layer was also studied. The optimal process parameters were determined as follows: laser power of 2 300 W, scanning speed of 250 mm/s, powder feeding speed of 24 g/min, and overlap rate of 70%. The results show that the hardness of the coating is between 754HV_0.2 and 831HV_0.2, which is 2.36 times to 2.60 times of the matrix hardness. Under the same conditions, the volume wear of the coating is only 3.64% of electroplated hard chromium coating.

The effects of different heat treatment processes on the microstructure and mechanical properties of RM80 steel were studied by means of scanning electron microscopy, Rockwell hardness tester and universal testing machine. As quenching temperature increases, carbides in RM80 steel gradually dissolve and the original austenite grains continue to grow. During tempering process, the structure of RM80 steel changes from tempered troostite to tempered sorbite, and martensite can still be observed in the structure of RM80 that is tempered after quenching at a higher temperature. After quenching at 1 150 ℃ and then three times of tempering at 550 ℃, RM80 steel finally has a good match between strength and plasticity, with a yield strength of 1 244 MPa, a tensile strength of 1 590 MPa, and an elongation of 12.0%.

Based on the calculation theory of solid-liquid two-phase flow and consideration of collision effect, a hydrodynamic model was established by using VOF model, and reamer operation under different working conditions was also analyzed by numerical simulation. It is shown that a reamer working with an inclination angle of 45° can have a good effect, resulting in percentage of disturbed area at 68.32%. As the rotating speed of reamer increases, disturbance of the waters above a reamer gradually becomes violent, and the scope of waters being disturbed also gradually becomes wider first and then narrows down. It is concluded that a reamer should work with an inclination angle of 45°, rotate at a speed of 45 r/min and move laterally at a speed of 0.2 m/s, which can reduce disturbance to the waters brought by its operation, thus minimize the secondary pollution to the waters to a certain extent.

A shear creep test was performed for weak intercalation in order to investigate influence of creep characteristics of weak intercalation on slope stability. The obtained curve from the test was fitted according to Cvisc creep constitutive model, and the creep of slope with weak intercalation was calculated by using finite difference method to analyze the variation in long-term displacement and shear strain increment of the slope. The results show that the weak intercalation has typical creep characteristics. The results obtained from the numerical calculation with Cvisc model are basically consistent with the actual monitoring data. The creep characteristics of weak intercalation cause not only increase in the displacement, but also significant changes in the distribution form and orientation of the overall displacement of the slope, especially greater displacement at the top and in the middle of the slope. As a result, the slope body experiences an increment in the shear strain, which is then expanded and finally tends to stable.

In Bangzhong Zinc-Copper Mine in Tibet, a mining method consisting of stoping followed by backfilling is adopted to excavate ores. In order to further improve production efficiency and economic benefits in the mine, rock mass quality was classified based on the investigation of geoengineering and geomechanics and rock mechanics test, and key factors influencing stability of stopes were analyzed in combination with the layout of mining and cutting engineering. On this basis, stope structure parameters were optimized by using a variety of empirical stability charts. The results show that the improved stability chart is highly adaptable and a stop with span extended from 12.5 m to 20 m can still meet safety requirement in the mining production.