Based on studies on the chemical phase-analysis methods for rubidium in some mineral ores from Hunan Shizhuyuan mine, the occurrence state and mass fraction of rubidium in minerals were preliminarily determined by using inductively coupled plasma optical emission spectrometer (ICP-OES), combined with XRD, SEM, electron probe and MLA. After the phase separation of rubidium was determined and appropriate selective reagents and reaction conditions were selected, rubidium in mica, rubidium in fluorite, rubidium in silica-aluminum oxide, rubidium in feldspar, and rubidium in insoluble minerals were all analyzed. Then, a method for rubidium phase analysis was developed. It is found that this analysis method is characterized by lower detection limit, high precision, good reproducibility, wider linear range, and simple and rapid process. Based on an experiment on the interference of alkali metallic elements in minerals, reasonable analysis methods were selected according to different concentrations of K, Na and Li, so as to obtain accurate results with less interference.

Based on the study on reduction behavior of vanadium during the smelting of vanadium-bearing titanium concentrate in an electric furnace, the comprehensive recovery of vanadium resources was explored through experiments. The vanadium-bearing titanium concentrate from Yunnan Province was taken as raw material to carry out an industrial-scale smelting experiment in an electric furnace with different carbon ratios. Based on the thermodynamic theory, the distribution and influencing factors of vanadium element in slag-iron phase were all analyzed. The results show that with carbon ratio up from 6.5% to 14.0%, the mass fraction of TiO₂ in titanium slag increases from 54.12% to 92.51%, the proportion of vanadium element reduced into molten iron increases from 1.14% to 6.61%, and the proportion of vanadium element left in the titanium slag decreases from 92.95% to 88.17%. It is found that there is a small amount of vanadium in dust, accounting for about 5.5%, which has no significant correlation to carbon ratio. The smelting process of titanium slag is not conducive to vanadium reduction, which is principally attributed to carbon deficiency operation and low-basicity slag system. It is not economically feasible to extract vanadium from molten iron by smelting vanadium-bearing titanium concentrate in an electric furnace, so it is suggested that vanadium should be extracted from the vanadium mud obtained after refining and vanadium removal process of titanium dioxide.

In view of problems of low conversion and low productivity in preparation of benzoquinone by the oxidation of aniline, a leaching process with a shear-enhancement approach was adopted to investigate the effects of adding amount of pyrolusite, acidity, shear rate, and liquid-solid ratio on the conversion rate of p-benzoquinone. It is found that high-speed shearing can accelerate the homogenization of pyrolusite and aniline, and enhance the oxidation reaction, resulting in efficient conversion of aniline. Under optimized process conditions, including acidity of 90 g/L, shear rate of 2 500 r/min, liquid-solid ratio of 5∶1, pyrolusite addition at 1.6 times theoretical amount, the conversion rate of p-benzoquinone is 91.23%. Compared to traditional mechanical stirring process, the reaction time can be significantly shortened and the conversion rate of p-benzoquinone can be significantly increased. It is concluded that the leaching process with shear-enhancement approach can have a promising future in industrial application.

With coal-based carbon as a hard template and zinc acetate as zinc source, a kind of ZnO nanomaterial with excellent crystal structure and pore properties was synthesized by adopting high-temperature roasting process. Then, the sensitivity of a gas sensor based on this ZnO nanomaterial to ethanol gas was investigated. The results are shown as follows: such ZnO sensor at 200 ℃ presents higher sensitivity to lowly-concentrated ethanol gas, with a response value of 5.25; the response time and recovery time of the ZnO sensor to the ethanol gas with concentration of 1×10^-5 are 10 s and 6 s respectively; the ZnO sensor has its sensitivity to ethanol gas in a linear relationship with the concentration of ethanol gas, and can detect the lowest concentration level of 1×10^-7; the ZnO sensor has a lower sensitivity to those kinds of gas, including acetic acid, methanol, ammonia and methane. Due to its higher sensitivity to ethanol gas, it is concluded that such sensor presents excellent selectivity in gas detection.

Effect of step quenching at different temperatures on mechanical and corrosion properties of Al-Mg-Si-Cu alloy was explored by carrying out room temperature tensile test, intergranular corrosion test, electrochemical corrosion test, as well as by means of transmission electron microscopy (TEM). It is found that the alloy, after 60 minutes of step quenching at 100 ℃ followed by 28 days of natural aging, can not only maintain a low yield strength of 162.49 MPa and a high strengthening increment of 105.60 MPa, but also exhibit a 57.2% reduction in intergranular corrosion depth compared to water-quenched alloy. TEM and EDS analyses show that type II Mg-Si clusters formed during step quenching effectively inhibit type I clusters formed during natural aging, while promote precipitation of intergranular β″ phase and β′ phase. Moreover, the precipitated phase at grain boundary is coarse and spherical with discrete distribution due to depletion of nearby solute atoms.

Al-Cu-Mg-Ag alloy melt was treated with ultrasonic waves, and the effect of the ultrasonic melt treatment on the microstructure and hardness of alloy was investigated. The results show that compared to the as-cast alloy without ultrasonic treatment, the as-cast alloy after ultrasonic melt treatment for 90 s and 180 s respectively has its hardness correspondingly improved by 12.7% and 11.2%. The ultrasonic melt treatment can reduce the segregation of alloy composition and accelerate precipitation of Ω phase during 2 h aging process at 200 ℃. A quantitative analysis shows that ultrasonic melt treatment can reduce the grain size of as-cast alloy, but presents limited effect of fine grain strengthening. Solid solution strengthening and precipitation strengthening respectively improve the hardness of as-cast and T6-tempered alloys.

In view of low prediction accuracy and slow speed of traditional prediction methods for strip crown, a weighted prediction model based on random forest (RF) and support vector machine (SVM) was established. The parameters of models based on RF, SVM, and a combination of RF and SVM were optimized respectively by adopting the improved coati optimization algorithm (ICOA), so as to improve crown prediction accuracy. A 1 580 mm production line of a hot-rolling mill in one company was taken in a simulation research on crown prediction based on its actual measurement. The root mean square error of the weighted prediction model based on RF and SVM is 2.23 μm. It is found that this weighted prediction model has its prediction accuracy increased by 7.08% and 2.62% respectively, compared with the models based on RF and SVM respectively.

A composite photocatalyst of TiO₂-CNTs was synthesized by adopting the sol-gel method and ultrasonic dispersion, and then its activity in the photocatalytic reduction of CO₂ was tested. With a load capacity of carbon nanotubes (CNTs) at 0.75%, the TiO₂-CNTs present a better performance in photocatalytic CO₂ reduction. Under UV irradiation with wavelength of 365 nm, the average yield of CH₄ and CO from the composite catalyst are enhanced by 90% and 156% respectively, compared to the usage of single TiO₂ catalyst. It is believed that the reaction is based on the following mechanisms: CNTs, as a co-catalyst, forms a compact electron transport structure with semiconductor of TiO₂, which significantly accelerates the transfer of photogenic carriers and reduces the electron-cave recombination efficiency. In addition, high specific surface area and excellent adsorption performance of CNTs can increase active sites for reaction, thus improving efficiency of photocatalytic reduction of CO₂ by the catalyst.

Effects of heat treatment system and Cu content on the microstructure and mechanical properties of two conventionally cast Al-Cu-Mn alloys were investigated. It is found that after treatment at proper temperatures, including 525 ℃×16 h+170 ℃×8 h for Cu2.8 alloy, 525 ℃×16 h+170 ℃×14 h for Cu5.7 alloy, the Cu2.8 alloy and Cu5.7 alloy have their tensile strength up to 209.76 MPa and 349.15 MPa respectively, and yield strength reaching 107.15 MPa and 216.21 MPa correspondingly. The detailed exploration of precipitation behavior of the alloy after aging indicates that Cu content brings an important influence to the precipitation behavior. The precipitation of the T phase leads to depletion of Cu atoms in low-Cu alloy during solid solution process. The θ′ phases only adhere near the T phase, and dispersed θ″ phases are only precipitated in the high-Cu alloy, which contribute mainly to higher strength of high-Cu alloy.

A kind of silicon monoxide-based anode material coated with layers of lithium titanate and carbon was synthesized by chemical vapor deposition and sol-gel method. The electrochemical measurement shows that with lithium titanate coating at an amount of 3%, the anode material presents good performance, showing that the specific capacity is 1 485.4, 1443.8, 1386.4, 1341 and 1276.2 mAh/g correspondingly at 0.2C, 0.5C, 1C, 2C and 4C rate respectively, and the specific capacity is 1 138.1 mAh/g after 150 charge-discharge cycles at current density of 750 mA/g. The flexible carbon layer can buffer volume expansion of the internal silicon core and improve the conductivity of the material. The rigid lithium titanate can ensure structural integrity of the material. The synergy of two layers of coatings can effectively improve cycle stability, rate performance and reversible capacity of electrode material.