With Ba (OH)₂·8H₂O and Ti (OC₄H₉)₄ as raw materials, and isopropanol (IPA) as solvent, tetragonal-rich BaTiO₃(BTO) nanopowder was synthesized by adopting solvothermal process. Effects of Ba/Ti ratio, pH value, solvothermal temperature and time on synthesis of tetragonal-rich BTO powders were investigated, and the mechanism of IPA in the solvothermal process for synthesis of BTO powders was also characterized by X-ray diffraction and scanning electron microscopy. It is found that in the solvothermal process, IPA will preferentially provide certain—OH to promote the hydrolysis of Ti (OC₄H₉)₄, generating TiO₆ octahedra to interconnect with Ba²⁺, which is gradually transformed into the tetragonal phase BaTiO₃ with regular morphology after phase transition, dissolution of small particles, and recrystallization in a low alkalinity environment. Experimental results show that under the following conditions including Ba/Ti ratio of 1.6, pH of 10 for the system, a solvothermal process at 220 ℃ for 24 h, calcination at 950 ℃ for 2 h, the synthesized tetragonal-rich BTO nanopowder is well dispersed with regular morphology, square or nearly square shape, with c/a value of 1.009 4 and particle size of 124 nm on average.

To study the effects of welding parameters on the tolerance of friction stir welding (FSW) of dissimilar aluminum alloys, the mechanical properties and structure of joint of dissimilar aluminum alloys (A356 and AA6061) by FSW under different welding parameters were studied by means of micro-hardness testing, tensile mechanical properties testing, scanning electron microscopy among other analytical testing means. The results show that as for the workpieces with the gap from 0 mm to 1 mm, the welded joint has tensile strength decreased significantly and presents visible welding defects. With tool pin of the same specification, the material flow can be promoted by decreasing the welding speed from 120 mm/min to 80 mm/min, thus the tolerance of workpiece gap will be greatly improved. The tool pin with diameter increased from 4 mm to 6 mm can lead to higher tolerance for welding, but also the material with a higher fusion degree and without delamination.

The effects of brightening agent, such as polysodium dithiodipropanesulfonate (SPS) and sodium 3-mercapto-1-propanesulfonate (MPS), on electrodeposition of Cu from electrolyte with Cu²⁺, H₂SO₄, Cl^- concentration of 85 g/L, 100 g/L and 20 mg/L respectively were studied by adopting linear scanning voltammetry and cyclic voltammetric stripping (CVS), and the effects of SPS and MPS on the tensile strength, elongation, glossiness and roughness of electrolytic copper foil for Li-ion batteries were discussed. The results show that SPS and MPS can promote copper electrodeposition, and also SPS is better than MPS in promotion. However, the compounding with collagen and hydroxyethylcellulose will result in less promotion of copper electrodeposition. In addition, SPS is conducive to improving the tensile strength of copper foil, and MPS is conducive to improving the elongation of copper foil. With concentration of SPS and MPS at 1 mg/L and 1.5 mg/L respectively, the prepared copper foil has flat and dense surface, with better glossiness and roughness.

Based on the experimental study on fragmentation and pulverization characteristics of polymetallic nodules in the process of ore lifting, it is found that there is obvious fragmentation of nodules during lifting process. With the volume concentration of 6.5%, the mass percent of polymetallic nodules with particle size larger than 50 mm decreases from 75.58% to 23.78%; with the volume concentration of 15%, the mass percent decreases from 51.51% to 10.08%. Pulverization of nodules was observed in the experiment. With the volume concentration of 6.5%, the mass percent of the polymetallic nodules powder with particle size less than 0.1 mm is 1.79%, and the median particle size is 10.07 μm; with the volume concentration of 15%, the mass percent of polymetallic nodule powder with particle size less than 0.1 mm is 1.99%, and the median particle size of the powder is 9.47 μm. Based on the experimental data, it is estimated that as per mining of 10 million tons of polymetallic nodules, the powder discharge will cause tens of thousands of tons of Fe and Mn losses, as well as hundreds of tons of Co, Ni and Cu losses. Besides, the maximum redeposition thickness of the sediment plume induced by mining is more than 3 mm after diffusion and settlement, which will bring a significant impact to environment.

In order to determine the reasonable air-deck length in underground vertical deep-hole blasting, the internal distribution function of impact pressure on hole wall with different air-deck length in multi-stage air deck blasting was analyzed based on the detonation wave theory. According to the Mises criterion, the reasonable reference values of air-deck length were obtained for different kinds of rock, which was verified by numerical simulation and on-site blasting test. The results show that the impact pressure on the hole wall of the air deck drops abruptly from both sides to the center along the axis of the hole, but increases slightly around the midpoint, and the pressure distribution presents a symmetrical W-shaped curve, with much higher values on two sides, lower in the middle section, and slightly higher around the center.

Based on the time-domain coupling analysis method, a three-dimensional nonlinear hydrodynamic model for mother vessel, deep-sea mining equipment and umbilical cable was established, and numerical calculation and analysis were also conducted for the hydrodynamic response characteristics of umbilical cable during launch and recovery. The results show that deep-sea mining equipment (weighing 10 t in water) can be safely launched and recovered at a speed of 0.8 m/s under condition of sea state 4. Due to the influence of both waves and currents, the deep-sea mining equipment will have strong oscillations and swings at the beginning of launch and at the end of recovery, which can be reduced by installing anti-swaying devices.

The influences of physical and mechanical properties of overlying filler on the shear strength characteristics of composite liner interface were studied by adopting a modified ZLB-1 triple rheological direct shear apparatus, and shear stress-strain curves of overlying filler under different normal stresses were obtained. The experimental results show that both clay and sand present displacement softening behavior, which becomes more obvious with the increase of sand content. Among the interface of composite liners, the interface between geomembrane and sodium bentonite pad has the lowest friction coefficient, and the friction coefficient in saturated state is significantly lower than that in the unsaturated state. As the sand content increases, the pseudo-cohesion between the interface of composite liner decreases, while the pseudo-friction angle initially decreases, and then increases followed by another decrease. As the water content increases, both the pseudo-cohesion and pseudo-friction angle decrease after an initial increase.

The stability of slope with fault under the impact of blast-induced seismic wave was analyzed by using simulation to study the dynamic response of slope with different fault thickness under the impact of explosive vibration. The results show that there exists elevation amplification effect when blast-induced seismic wave propagates along slope surface and fault area. The thicker the fault, the faster the attenuation of blast-induced seismic wave. As the fault becomes thicker, the displacement of slope under the action of blast-induced vibration gradually increases, and the overall deformation resistance becomes smaller. Under the action of blast vibration, the fault with different thickness obviously brings different influence to slope stability. With the fault thickness of 2-8 m, the slope stability decreases continuously and rapidly, and tends to be stable as the fault thickness exceeds 8 m.

Based on typical nonlinear negative exponent constitutive relations and catastrophe characteristic of weakened mineral rock, the variation of energy transformation and time effectiveness with mechanism stiffness in catastrophic and non-catastrophic breakup were analyzed. The results show that the catastrophic breakup induced by low mechanism stiffness will dramatically reduce the energy transformation efficiency of dynamical system and time effectiveness of rock breakage. From the perspective of energy utilization and rock-breaking efficiency, it is not appropriate to equip a dynamical system for rock breakage with low mechanism stiffness. Finally, an appropriate range of mechanism stiffness is provided for reference in design.

The single application of analytical hierarchy process (AHP) and grey relational analysis (GRA) algorithm is always affected by some subjective factors, leading to great deviation between the obtained evaluation result and the actual result. In view of this problem, a composite algorithm based on an integrated range analysis with GRA and AHP was proposed. Then, a phosphate mine in the southwest China was taken as an example, and this algorithm was adopted to analyze the sensitivity of factors, including gravity, internal friction angle, cohesive force, elastic modulus and Poisson's ratio, to the stability of slope in the Area A. The results show that the sensitivity of those influencing factors to the slope stability in Area A is in the following descending order: internal friction angle, cohesive force, gravity, elastic modulus, Poisson's ratio. It is found that the analysis result is consistent with the actual situation of the mine.