To investigate the impact of an opening and joints with different inclination angles on the mechanical response behavior, the energy evolution characteristics, and distribution law of granite specimens, uniaxial loading tests were performed on the parallel jointed rock samples with an opening. Results indicated an initial decreasing trend of the strength and deformation parameters, which later increases with increased inclination angle, reaching minimum values when the inclination angle is 45°. Evolution curves of the elastic strain energy and dissipated energy with strain of the samples showed step-like gradual mutation characteristics. The peak total energy, peak elastic strain energy, peak dissipated energy, and total input energy during the failure of the samples showed significant nonlinear characteristics with increasing inclination angle. The opening and joints as well as the change of the inclination angle had significant influences on the proportion of the elastic strain energy of the samples prior to the peak, resulting in the difference of the distribution law of input energy. Moreover, the energy mechanism of the sample failure was discussed. Results showed that the energy release was the internal cause of the sudden destruction of the entire rock mass.

The present study initially investigates the kinetics of microwave-assisted grinding and flotation in a porphyry copper deposit. Kinetic tests were conducted on untreated and microwave-irradiated samples by varying the exposure time from 15 to 150 s. Optical microscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy were conducted to determine the mineral liberation and particle surface properties, and to perform mineralogical analyses. Results showed that the ore breakage rate constant monotonically increased by increasing the exposure time, particularly for the coarsest fraction size (400 µm) due to the creation of thermal stress fractures alongside grain boundaries. Excessive irradiation time (>60 s) led to the creation of oxidized and porous surfaces along with a dramatic change in particle morphologies that result in a substantial reduction of chalcopyrite and pyrite flotation rate constants and ultimate recoveries. We concluded that MW-pretreated copper ore was ground faster than the untreated variety, but the two types have slightly similar floatabilities.

The inadvertent dissolution of gangue minerals is frequently detrimental to the flotation of valuable minerals. We investigated the effect of conditioning time on the separation of brucite and serpentine by flotation. By analyzing the Mg²⁺ concentration, relative element content, and pulp viscosity, we studied the effect of mineral dissolution on brucite flotation. The results of artificially mixed mineral flotation tests (with −10 μm serpentine) showed that by extending the conditioning time from 60 to 360 s, a large amount of Mg²⁺ on the mineral surface gradually dissolved into the pulp, resulting in a decreased brucite recovery (from 83.83% to 76.79%) and an increased recovery of serpentine from 52.12% to 64.03%. To analyze the agglomeration behavior of brucite and serpentine, we used scanning electron microscopy, which clearly showed the different adhesion behaviors of different conditioning times. Lastly, the total interaction energy, as determined based on the extended DLVO (Derjaguin–Landau–Verwey–Overbeek) theory, also supports the conclusion that the gravitational force between brucite and serpentine increases significantly with increased conditioning time.

The effect of CaCO₃, Na₂CO₃, and CaF₂ on the reduction roasting and magnetic separation of high-phosphorus iron ore containing phosphorus in the form of Fe₃PO₇ and apatite was investigated. The results revealed that Na₂CO₃ had the most significant effect on iron recovery and dephosphorization, followed by CaCO₃, the effect of CaF₂ was negligible. The mechanisms of CaCO₃, Na₂CO₃, and CaF₂ were investigated using X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectrometry (SEM–EDS). Without additives, Fe₃PO₇ was reduced to elemental phosphorus and formed an iron–phosphorus alloy with metallic iron. The addition of CaCO₃ reacted with Fe₃PO₇ to generate an enormous amount of Ca₃(PO₄)₂ and promoted the reduction of iron oxides. However, the growth of iron particles was inhibited. With the addition of Na₂CO₃, the phosphorus in Fe₃PO₇ migrated to nepheline and Na₂CO₃ improved the reduction of iron oxides and growth of iron particles. Therefore, the recovery of iron and the separation of iron and phosphorus were the best. In contrast, CaF₂ reacted with Fe₃PO₇ to form fine Ca₃(PO₄)₂ particles scattered around the iron particles, making the separation of iron and phosphorus difficult.

Iron carbon agglomerates (ICA) are used to realize low-carbon blast furnace ironmaking. In this study, the central composite design based on response surface methodology was used to synergistically optimize the compressive strength, reactivity, and post-reaction strength of ICA. Results show that the iron ore addition ratio significantly influences the compressive strength, reactivity, and post-reaction strength of ICA. The iron ore addition ratio and carbonization temperature or the iron ore addition ratio and carbonization time exert significant interaction effects on the compressive strength and reactivity of ICA, but it has no interaction effects on the post-reaction strength of ICA. In addition, the optimal process parameters are as follows: iron ore addition ratio of 15.30wt%, carbonization temperature of 1000°C, and carbonization time of 4.27 h. The model prediction results of compressive strength, reactivity, and post-reaction strength are 4026 N, 55.03%, and 38.24%, respectively, which are close to the experimental results and further verify the accuracy and reliability of the models.

A green method of super-gravity separation, which can enhance the filtration process of bismuth and copper phases, was investigated and discussed for the rapid removal of copper impurity from bismuth–copper alloy melts. After separation by the super-gravity field, the bismuth-rich liquid phases were mainly filtered from the alloy melt along the super-gravity direction, whereas most of the fine copper phases were retained in the opposite direction. With optimized conditions of separation temperature at 280°C, gravity coefficient at 450, and separation time at 200 s, the mass proportion of the separated bismuth from the Bi–2wt%Cu and Bi–10wt%Cu alloys respectively reached 96% and 85% , which indicated the minimal loss of bismuth in the residual. Simultaneously, the removal ratio of impurity copper from the Bi–2wt%Cu and Bi–10wt%Cu alloys reached 88% and 98%, respectively. Furthermore, the separation process could be completed rapidly and is environmentally friendly and efficient.

The evolution of inclusions and the formation of acicular ferrite (AF) in Ca–Ti treated steel was systematically investigated after Mg and La addition. The inclusions in the molten steel were Ca–Al–O, Ca–Al–Mg–O, and La–Mg–Ca–Al–O after Ca, Mg, and La addition, respectively. The type of oxide inclusion in the final quenched samples was the same as that in the molten steel. However, unlike those in molten steel, the inclusions were Ca–Al–Ti–O + MnS, Ca–Mg–Al–Ti–O + MnS, and La–Ca–Mg–Al–Ti–O + MnS in Mg-free, Mg-containing, and La-containing samples, respectively. The inclusions distributed dispersedly in the La-containing sample. In addition, the average size of the inclusions in the La-containing sample was the smallest, while the number density of inclusions was the highest. The size of effective inclusions (nucleus of AF formation) was mainly in the range of 1–3 μm. In addition, the content of ferrite side plates (FSP) decreased, while the percentage of AF increased by 16.2% due to the increase in the number of effective inclusions in the La-containing sample in this study.

The evolution behavior of the γ″ phase of IN718 superalloy in a temperature/stress coupled field was investigated. Results showed that the coarsening rate of the γ″ phase was significantly accelerated in the temperature/stress coupled field. Based on the detail microstructural and crystal defect analysis, it was found that the coarsening rate of the γ″ phase with applied stress was significantly higher than that without stress. The main reasons for the increase in the coarsening rate of the γ″ phase are as follows: the vacancy formation energy is decreased by the applied stress, which leads to an increase in the vacancy concentration; in the temperature/stress coupled field, the Nb atoms easily combine with vacancies to form complexes and diffuse with the complexes, resulting in a significant increase in the Nb atom diffusion coefficient; Nb atom diffusion is the key control factor for the coarsening of the γ″ phase.

To investigate the oxidation behavior of a nickel-based superalloy with high hafnium content (1.34wt%), this study performed isothermal oxidation tests at 900, 1000, and 1100°C for up to 200 h. X-ray diffraction and scanning electron microscopy with energy-dispersive X-ray spectroscopy were applied to study the oxidation behavior. The weight gain of the high Hf nickel-based superalloy exhibited a parabola-like curve, and no spallation of the oxide scale was observed during the oxidation tests. The alloy presented excellent oxidation resistance, and no HfO₂ was observed in the oxide scale at 900°C. With the increase of the oxidation temperature to 1000°C, HfO₂ particles formed in the spinel phases of the scale, and “peg-like” HfO₂ was observed within and beneath the inner layer of Al₂O₃ after 200 h. As the oxidation temperature rose to 1100°C, “peg-like” HfO₂ was observed at the early stage of the oxidation test (within 25 h). The formation mechanism of HfO₂ and its impact on oxidation resistance were investigated based on the analysis of the oxidation test results at different temperatures.

In this study, Mg–9Al–1Si–1SiC (wt%) composites were processed by multi-pass equal-channel angular pressing (ECAP) at various temperatures, and their microstructure evolution and strengthening mechanism were explored. Results showed that the as-cast microstructure was composed of an α-Mg matrix, discontinuous Mg₁₇Al₁₂ phase, and Chinese script-shaped Mg₂Si phase. After solution treatment, almost all of the Mg₁₇Al₁₂ phases were dissolved into the matrix, whereas the Mg₂Si phases were not. The subsequent multi-pass ECAP at different temperatures promoted the dynamic recrystallization and uniform distribution of the Mg₁₇Al₁₂ precipitates when compared with the multi-pass ECAP at a constant temperature. A large number of precipitates can effectively improve the nucleation ratio of recrystallization through a particle-stimulated nucleation mechanism. In addition, the SiC nanoparticles were mainly distributed at grain boundaries, which effectively prevented dislocation movement. The excellent comprehensive mechanical properties can be attributed to grain boundary strengthening and Orowan strengthening.

Bimetal materials derived from transition metals can be good catalyst candidates towards some specific reactions. When loaded on graphene (GP), these catalysts exhibit remarkable performance in the hydrolysis of sodium borohydride. To obtain such catalysts easily and efficiently, a simple thermal reduction strategy was used in this study, and Ni_xCo_10−x series bimetal catalysts were prepared. Among all the catalysts, Ni₁Co₉ exhibited the best catalytic performance. The turnover frequency (TOF) related to the total number of atoms within the bimetallic nanoparticles reached 603.82 mL·mmol⁻¹·min⁻¹ at 303 K. Furthermore, graphene was introduced as a supporting frame. The Ni₁Co₉@Graphene (Ni₁Co₉@GP) had a large surface area and high TOF, 25534 mL·mmol⁻¹·min⁻¹, at 303 K. The Ni₁Co₉@GP exhibited efficient catalytic properties for H₂ generation in alkaline solution because of its high specific surface area. Moreover, the high kinetic isotope effect observed in the kinetic studies suggests that using D₂O led to the oxidative addition of an O–H bond of water in the rate-determining step.

Radioluminescence (RL) behaviour of erbium-doped yttria nanoparticles (Y₂O₃:Er³⁺ NPs) which were produced by sol–gel method was reported for future scintillator applications. NPs with dopant rates of 1at%, 5at%, 10at% and 20at% Er were produced and calcined at 800°C, and effect of increased calcination temperature (1100°C) on the RL behaviour was also reported. X-ray diffraction (XRD) results showed that all phosphors had the cubic Y₂O₃ bixbyite-type structure. The lattice parameters, crystallite sizes (CS), and lattice strain values were calculated by Cohen-Wagner (C-W) and Williamson-Hall (W-H) methods, respectively. Additionally, the optimum solubility value of the Er³⁺ dopant ion in the Y₂O₃ host lattice was calculated to be approximately 4at% according to Vegard’s law, which was experimentally obtained from the 5at% Er³⁺ ion containing solution. Both peak shifts in XRD patterns and X-ray photoelectron spectroscopy (XPS) analyses confirmed that Er³⁺ dopant ions were successfully incorporated into the Y₂O₃ host structure. High-resolution transmission electron microscopy (HRTEM) results verified the average CS values and agglomerated NPs morphologies were revealed. Scanning electron microscopy (SEM) results showed the neck formation between the particles due to increased calcination temperature. As a result of the RL measurements under a Cu K_α X-ray radiation (wavelength, λ = 0.154 nm) source with 50 kV and 10 mA beam current, it was determined that the highest RL emission belonged to 5at% Er doped sample. In the RL emission spectrum, the emission peaks were observed in the wavelength ranges of 510–575 nm (²H_11/2, ⁴S_3/2–⁴I_15/2; green emission) and 645–690 nm (⁴F_9/2–⁴I_15/2; red emission). The emission peaks at 581, 583, 587, 593, 601, 611 and 632 nm wavelengths were also detected. It was found that both dopant rate and calcination temperature affected the RL emission intensity. The color shifted from red to green with increasing calcination temperature which was attributed to the increased crystallinity and reduced crystal defects.

Layered double hydroxides (LDHs) hinder corrosive elements by forming a double layer and locking them between its layers. Hence, LDHs are interesting materials in corrosion inhibition. In this work, Zn–Mg-based LDHs are grown over a copper substrate by using a hydrothermal method. Two types of Zn–Mg-based LDH coating are prepared based on hydrothermal reaction time. Both types are characterized through Fourier transform infrared spectroscopy, Raman spectroscopy, high-resolution scanning electron microscopy, energy dispersive X-ray analysis, atomic force microscopy, and X-ray diffraction. Results show that the two types of LDH coating are successfully grown on copper; however, they differ in thickness and structural configuration. Corrosion testing of the LDH coatings is executed in 0.1 M NaCl and 0.1 M NaOH through alternating current impedance measurements and Tafel polarization curves. Results show that L48 gives more than 90% protection to copper, which is higher than the protection provided by L24. However, both LDH coatings (L24 and L48) are more effective corrosion inhibitors in NaCl than in NaOH, suggesting that the LDH coatings can more efficiently exchange Cl ions than OH ions.

Graphene oxide (GO) wrapped Fe₃O₄ nanoparticles (NPs) were prepared by coating the Fe₃O₄ NPs with a SiO₂ layer, and then modifying by amino groups, which interact with the GO nanosheets to form covalent bonding. The SiO₂ coating layer plays a key role in integrating the magnetic nanoparticles with the GO nanosheets. The effect of the amount of SiO₂ on the morphology, structure, adsorption, and regenerability of the composites was studied in detail. An appropriate SiO₂ layer can effectively induce the GO nanosheets to completely wrap the Fe₃O₄ NPs, forming a core-shell Fe₃O₄@SiO₂@GO composite where Fe₃O₄@SiO₂ NPs are firmly encapsulated by GO nanosheets. The optimized Fe₃O₄@SiO₂@GO sample exhibits a high saturated adsorption capacity of 253 mg·g⁻¹ Pb(II) cations from wastewater, and the adsorption process is well fitted by Langmuir adsorption model. Notably, the composite displays excellent regeneration, maintaining a ~90% adsorption capacity for five cycles, while other samples decrease their adsorption capacity rapidly. This work provides a theoretical guidance to improve the regeneration of the GO-based adsorbents.