7075 Al alloy is a kind of alloy material with high strength and excellent wear resistance，which is widely used in aerospace，automotive and other fields. In recent years，the application of 7075 aluminum alloy in marine vessels has gradually increased with the proposal of marine energy strategy. However，despite its good mechanical properties and strength，its corrosion resistance in marine environment is unsatisfactory and susceptible to corrosion，which seriously affects its safety and service life，and limits its large-scale application in the field of 7075 Al alloy in the field of marine engineering，national defense industry and others. In order to solve this problem，researchers are constantly searching for ways to improve the alloy，such as alloy surface coating technology，alloy formulation optimization，etc.，to improve the corrosion resistance of 7075 Al alloy in marine environment. Micro arc oxidation (MAO) technology is one of the effective ways to improve the surface properties of aluminum alloys by combining the electrolyte and appropriate electrical parameters so that the metal on the surface of the substrate interacts with the electrolyte solution，forming a ceramic film layer on the surface of the substrate，which is dominated by the metal oxides of the substrate. This technique can significantly improve the surface hardness，wear resistance，corrosion resistance and other properties of the material，which is of great importance in improving the overall performance of aluminum alloys. The pH of the electrolyte is a key parameter affecting the microstructure，mechanical properties and physical and chemical properties of the micro-arc oxidation film layer. Different pH leads to changes in the composition and structure of the film layer，which in turn affects its hardness，wear and corrosion resistance，and other properties. Therefore，in the micro-arc oxidation process，proper control of the pH of the electrolyte is essential to achieve the desired performance of the film layer. The film layer was prepared on the surface of 7075 aluminum alloy by using micro-arc oxidation technology in this paper. By adjusting pH of the electrolyte，the effects of different pH on the microstructure and corrosion resistance of the micro-arc oxidized film layer were investigated. Aiming to understand the influence mechanism of pH change on the performance of the film layer during the micro-arc oxidation process，and to provide theoretical support and experimental basis for the optimization of the micro-arc oxidation process. The surface morphology of the membrane layers prepared with different pH electrolytes was observed using scanning electron microscope （SEM），and the changes in micropore distribution，pore size，and porosity of the membrane layers were analyzed using Image-J software. Meanwhile，an eddy current thickness gauge was used to check the thickness variation of the membrane layer. Vickers microhardness tester was used to evaluate the hardness of the membrane layer. In addition，the corrosion resistance was tested in 3.5% NaCl （mass fraction） solution using an electrochemical workstation. Tafel fitting method was used to obtain the corresponding electrochemical parameters to quantitatively analyze the changes in corrosion performance of 7075 aluminum alloy before and after micro-arc oxidation treatment. And the effects of pH changes on the microstructure，thickness，hardness，and corrosion resistance of the membrane layer were systematically analyzed.The results showed that the micro-arc oxidation treatment could significantly improve the corrosion resistance of 7075 aluminum alloy. As pH of the electrolyte increased，the breakdown voltage during the micro-arc oxidation process decreased，resulting in the generation of finer discharge sparks，the number of large-size micropores （diameter larger than 2.5 μm） or the total number of micropores decreased and then increased，and the porosity of the film layer showed a tendency to decrease and then increase，while the hardness and thickness of the film layer showed the opposite tendency. Moreover，the corrosion resistance of the samples was improved. The self-corrosion current and corrosion rate of the micro-arc oxidized film layer showed a trend of decreasing and then increasing with the increase of pH，and the trend of self-corrosion voltage was opposite. When pH of the electrolyte was 12.7，the surface film layer of 7075 aluminum alloy showed the best corrosion resistance，with self-corrosion potential of -0.6 V，self-corrosion current of 4.74×10⁻⁷ A·cm⁻²，corrosion rate of 0.0056 mm·a⁻¹ and polarization resistance value of 18.7×10³ Ω·cm²，which was about one order of magnitude lower than that of 7075 aluminum alloy. However，when pH of the electrolyte was too high，the growth rate of the coating slowed down，the film layer became thinner and the corrosion resistance decreased.

Nickel as an important strategic metal，is widely used in military manufacturing and new energy fields，due to the rapid development of new energy，the price of nickel is gradually rising，and the competition for nickel resources is becoming increasingly fierce. With the depletion of easily processed and highly valuable nickel ore resources，difficult to treat nickel ore resources，especially nickel silicate ore resources，are gradually receiving attention. Nickel silicate ore is a relatively difficult to treat nickel ore，especially low-grade nickel silicate ore，the current methods for treating nickel silicate mainly include nickel matte smelting，nickel iron smelting，reduction roasting ammonia leaching method，chlorination separation roasting magnetic separation method，high-pressure acid leaching method，etc. The first two methods mentioned above are suitable for treating nickel ores with high nickel iron content，while the reduction roasting ammonia leaching method and chlorination separation roasting magnetic separation method are suitable for treating nickel ores with a nickel grade of about 1%. Although the high-pressure acid leaching method has a high nickel recovery rate，but it is mainly suitable for nickel oxide ores with low silicon and magnesium content，and there are problems such as high investment costs and equipment corrosion.At present，the nickel in the tailings of many nickel beneficiation plants is mainly nickel silicate，which is difficult to separate and can only be stacked in tailings ponds，causing waste of nickel resources，if the nickel silicate in the tailings of nickel beneficiation plants can be utilized，it will create significant economic benefits.In order to extract nickel from nickel silicate，an efficient method had been developed，the ultra-low grade nickel silicate ore was treated by using enhanced roasting leaching method in this paper. The influence of various factors on the leaching effect of nickel and magnesium was investigated，and the optimal process conditions were obtained. The mechanism of calcium fluoride improving the leaching rate of nickel and magnesium was revealed through X-ray diffraction （XRD），Fourier transform infrared spectrometer （FTIR） and scanning electron microscope （SEM）. The results showed that，under the conditions of roasting temperature of 1100 ℃，roasting time of 60 min，calcium fluoride dosage of 10%，leaching end point pH of 1.5，leaching temperature of 50 ℃，leaching time of 5 h，nickel leaching rate could reach 74.9%，magnesium leaching rate could reach 84.3%，the use of enhanced roasting leaching method could effectively extract nickel and magnesium from ores. It could be found from the experiment that the roasting of calcium fluoride could improve the leaching rate of nickel and magnesium in the roasting stage and leaching stage. The mechanism of calcium fluoride improving the leaching rate of nickel and magnesium was as follows：during the roasting process，fluoride ions dissociated from calcium fluoride replace O²⁻ and entered the mineral lattice，causing the stable bridging oxygen bonds in the mineral to break，causing the collapse of silica tetrahedra，strengthening the destruction of mineral crystal structure，and further releasing nickel and magnesium. In addition，in the leaching process，fluoride ion，nickel ion and magnesium ion were easy to form acid soluble nickel fluoride complexes and magnesium fluoride complexes，and increasing the stability of nickel and magnesium ions in the leaching solution. Moreover，fluoride ions were more likely to penetrate into the interior of the silicate structure，reducing the potential difference caused by hydrogen ion migration，promoting the diffusion of hydrogen ions within the silicate，and strengthening the displacement and desorption effect of hydrogen ions on nickel and magnesium in the silicate. At the same time，fluoride ion could corrode silicate mineral under acidic conditions，release nickel and magnesium ions adsorbed in minerals，and improve the leaching rate of nickel and magnesium under the combined action. The study explored the treatment of low grade by enhanced roasting leaching method from the perspectives of experimental results and mechanism，and it also provided a theoretical basis. Enhanced roasting leaching method could serve as a technical reserve，and as nickel prices gradually rose，the applicability of this method gradually became apparent.This study could provide certain reference and reference for the treatment of nickel silicate ore，and had important reference significance for nickel extraction in complex nickel ores，at the same time，it could also promote the development of nickel resource comprehensive utilization technology.

The existing heat-resistant alloys are gradually unable to meet the performance requirements of advanced materials，and it is generally believed that adding a small amount of rare earth elements to the alloy is beneficial for improving its oxidation resistance. Although the influence of rare earth elements on the high-temperature oxidation behavior of alloys has been studied by many scholars and various mechanism models have been proposed，none of them have been widely recognized. This article systematically reviewed the effects of rare earth elements Y，Ce，La and the common addition of several rare earth elements on the high-temperature oxidation behavior of alloys，and analyzed the mechanism of rare earth elements. The results indicated that the addition of rare earth elements could refine the alloy grain size，promote the formation of a complete and dense oxide film，and improve the alloy's oxidation resistance. On the other hand，it could change the diffusion mechanism of anions and cations in the oxide film，reduce the voids between the oxide film and the alloy matrix，and improve the anti-peeling property of the oxide film. However，there was an optimal content of rare earth elements to improve the oxidation resistance of alloys，and excessive addition could lead to accelerated oxidation. This article also looked forward to future research directions on the influence of rare earth elements on the high-temperature oxidation behavior of alloys. Meanwhile，based on the discussion of the oxidation process，the oxidation mechanism of rare earth elements on the alloy oxidation behavior was analyzed. The results indicated that the oxidation of alloys could be roughly divided into two stages：the initial oxidation stage and the stable oxidation stage. In the initial oxidation stage，the oxide film was not completely formed，which was the growth process of the oxide film. The oxide film of the alloy without the addition of rare earth elements presented a discontinuous state on the surface of the alloy，which could not effectively isolate the alloy from oxygen. Due to short-circuit diffusion，the first generated oxide aggregated at grain boundaries，and at this time，the oxide was mainly formed by the outward diffusion of alloy elements and the combination with oxygen. Due to the migration of a large number of alloying elements，voids were formed at the interface of oxides and alloys. The presence of these voids weakened the adhesion between the oxide film and the substrate，reducing the anti-peeling property of the oxide film. The alloy with added rare earth elements could quickly form a uniform and dense oxide film on the surface due to the increase in the number of grain boundaries and the provision of sufficient nucleation points by rare earth elements. Meanwhile，due to the aggregation of rare earth elements in the oxide film，the diffusion of alloy elements was blocked，and the diffusion mechanism in the oxide film changed from alloy elements （large atoms） diffusing outward to oxygen （small atoms） diffusing inward. At this point，the number of voids in the oxide film significantly decreased. In the stable oxidation stage，the oxide film had basically formed，which had a good protective effect on the alloy matrix，and the thickness of the oxide film generally did not increase and remains within a certain range. At this point，the alloy without the addition of rare earth elements continuously diffused towards the outer side of the oxide film，and the number of voids at the interface between the oxide film and the alloy gradually increased，resulting in a decrease in the adhesion between the oxide film and the matrix，and a decrease in the anti-peeling property of the oxide film. At the same time，due to the increase of tensile stress inside the oxide film，small longitudinal cracks appeared inside the oxide film，which would also promote the oxidation of the alloy. Moreover，alloys with added rare earth elements would grow some needle like oxides in the gaps of the oxide film，which effectively filled the gaps in the oxide film and make it denser. Due to the extremely complex oxidation process of multi-component alloys，and the oxidation temperature was usually above 800 ℃，it was difficult to observe in situ during the alloy oxidation process，which greatly hindered the understanding of the mechanism of rare earth elements in the high-temperature oxidation process of alloys. The studies had shown that the critical concentration of active components in alloys transitioning from internal oxidation to protective external oxidation was highly sensitive to the addition of trace rare earth elements. However，the role of rare earth elements in the oxidation process was not yet clear. The simple binary alloy systems with significant differences in oxide stability should be choosen to study the effects of adding various rare earth elements with different contents on their high-temperature oxidation behavior，in order to clarify the fundamental reasons for the drastic changes in the oxidation mode of the alloys.

With the progress and development of science and technology，the second-generation semiconductor materials represented by gallium arsenide （GaAs） have gradually replaced silicon materials in electronic communications，national defense，aerospace and other fields. Every year，a large amount of GaAs wastes are generated from the crystal growth in upstream，design and processing in midstream and scrap in downstream of the GaAs industry chain. Without in time treatment，the arsenic in GaAs wastes may enter the soil or groundwater with human activities and geological processes，posing a threat to the natural environment and human health. GaAs wastes are one of the main sources of arsenic and gallium resources because of its high grade and large stock. The clean and efficient recycling of GaAs wastes have received wide attention in recent years. This article started from the perspective of the gallium arsenide industry chain，the different recovery processes of GaAs crystal cutting scrap from upstream，GaAs processing wastes from midstream and used GaAs electronic devices were reviewed. The purity of GaAs scrap produced by cutting in the upstream of the industry chain was high，both wet and fire processes could achieve effective separation and recovery of arsenic and gallium. Acid leaching of GaAs cutting scrap，combined with selective precipitation，extraction，resin adsorption and alkaline electrolysis to recover gallium was a relatively mature technology for industrial recovery of GaAs at present. However，a large amount of acidic solution was added in the wet process and the generation of arsenic-containing waste water was inevitable. The processing process and production costs would increase as a result. In contrast，the fire process had shorter processes and simpler operations. But the oxidation roasting method and sulfurization heat treatment method also had the possibility of producing toxic gases containing arsenic. As a new method in recent years，the vacuum decomposition method recovered gallium and arsenic directly in elemental form under vacuum conditions，which had obvious advantages in terms of safety and efficiency，and it was one of the most promising GaAs recovery processes at present. However，the presence of GaAs clusters always affected the recovery rate，and further in-depth study was still needed. GaAs processing process in the middle reaches of the industrial chain such as cutting and grinding generated a large amount of GaAs containing waste water. The composition of waste slag and sludge from GaAs processing waste water by coagulation and sedimentation of iron compounds were complex. Impurities such as mixed iron had a major impact on the subsequent recovery process. Therefore，iron removal became a key issue in the recovery of GaAs processing wastes. Additives with stronger binding ability to Ga³⁺ were usually selected to extract gallium. Sometimes，arsenic and gallium resources in GaAs processing wastes were also prepared into compound products such as gallium oxide and sodium arsenate crystals. It was beneficial to shorten the waste recovery process，reduce the treatment cost and the discharge of arsenic-containing waste liquid. At the same time，it met the needs of gallium oxide semiconductor，sodium arsenate drugs and other aspects of China. In the downstream of the industry chain，GaAs was encased in organic casings in used electronic devices such as light-emitting diodes （LED），integrated circuits （ICs） and solar cells. The efficient removal of organic matter from used GaAs containing devices，extraction of GaAs and recycling of arsenic and gallium had become a research hotspot for many scholars. The hydrothermal treatment and thermal decomposition were the main methods to remove surface organic matter. The treatment effect of hydrothermal treatment on various used electronic devices was different，which was easy to cause the loss of arsenic. The oxidation of gallium on the surface of GaAs was easily caused by oxygen produced during the thermal decomposition of organic matter. Both of these pretreatment methods to remove organic matter were immature. In summary，the fire process had obvious advantages in recovering GaAs scrap with less impurities. But the industrial recovery of GaAs waste was still dominated by the more selective wet process at present. Based on the huge production and consumption of GaAs in China and the current situation of recycling various types of GaAs wastes，it was believed that there were still challenges in terms of recycling cost，safety，efficiency and product purity. In the future，the development of high performance and low cost extractants and chelating resins for wet process should be focused on. The scale of thermal recovery should be expanded，the arsenic condensation process should be optimized，and the purity of the recovered product should be balanced with the recovery rate. The special equipment for pretreatment of used GaAs electronic devices should be developed and gradually applied in industrial production. The properly combining wet and fire recycling processes to comprehensively improve the recycling efficiency of GaAs wastes. The development of China's semiconductor wastes recycling industry would be promoted towards high yield and efficiency.

With the gradual exhaustion of easy-to-treat gold mineral resources，gold production enterprises are pressured to utilize the refractory gold concentrate with high impurity contains arsenic and antimony as alternate. Since golds in these refractory ores are usually deposited with other metal sulphides and silicates，and mostly embedded in stibnites，pyrites and arsenopyrites，it is hard to achieve effective gold extraction by conventional wet process. Therefore，efficiently matte smelting capturing-Au technology have been adopted for treating refractory gold mixed copper concentrates. However，high-content of antimony seriously affect the lining life during matte smelting，and also have a negative impact on the subsequent recovery of valuable metals from anode slime. In consequence，it is of great significance to seek suitable technological strategies to pre-removed antimony from this high-Sb gold concentrates before being charged in bottom blowing melting furnace. In this work，Na₂S+NaOH alkaline leaching was adopted to pre-remove Sb from high-antimony containing gold concentrates. Based on the chemical composition and mineralogical phases analysis，the process parameters of alkaline leaching were determined according to thermodynamic analysis and electrochemical potential （E_h）-pH diagram. Then，single-factor experiment was carried out to detect the effect of Na₂S and NaOH concentration，temperature and liquid-solid ratio （L/S） on the leaching rate of Au and Sb，simultaneously，the inhibition mechanism of Mn to minimize co-leaching of gold caused by polysulfides and thiosulfates was also studied by means of electrochemistry analysis and X-ray photoelectron spectroscopy （XPS）. Furthermore，the gold contents in concentrates and leaching residues were analyzed by fire assay method，the chemical composition of others was analyzed by chemical titration and inductively coupled plasma mass spectrometry （ICP-MS）. Besides，the morphologies and phase structure were analyzed by scanning electron microscope-energy dispersive spectrometer （SEM-EDS），X-ray diffraction （XRD） and mineral phases analysis，especially the mineralogical phases of gold and antimony. The results showed that the major minerals in antimony bearing gold concentrates had been detected as stibnite （Sb₂S₃），arsenopyrite （FeAsS），pyrite （FeS₂） and quartz （SiO₂），etc. And antimony existed in a variety of forms，53% in the form of antimony sulfides and others were oxides. Moreover，the major antimony oxide was valentinite，and a few stibiconite and antimonate （Sb₂O₄），which was coexisted with pyrite，arsenopyrite and other flocculent substances. In addition，the gold was mainly wrapped by compounds such as sulfides and silicates，however，only a small amount of gold existed in the form of bare or semi-bare；among them，gold wrapped by antimony sulfide had the highest risk of loss in leaching. The appropriate addition of Na₂S concentration could effectively improve the leaching rate of antimony，but too much S²⁻ would lead to the addition of S₂O₃²⁻ and S_n²⁻ in leaching solution，which accordingly increased the leaching rate of gold. Corresponding，the addition of NaOH could inhibit the hydrolysis of Na₂S；instead，too high NaOH might remarkably accelerate the conversion rate of S²⁻ to elemental sulfur，and restrain the dissolution and mass transfer of stibnite and antimony oxides. In view of the above，it was suitable to select Na₂S 100 g·L⁻¹+NaOH 100 g·L⁻¹ for pre-removing antimony from refractory gold concentrates in leaching process. The rising temperature could effectively improve the reaction kinetic conditions，and the most important，it also reduced the content of dissolved oxygen in leaching solution，which might accordingly promote the leaching rate of antimony and suppress gold's dissolution. However，too high temperature dramatically intensified the decomposition of Na₂S，in turn reducing the leaching rate of antimony. An appropriate L/S reduced the viscosity of solution and speeded up the leaching rate of antimony，but excessive L/S also increased the dissolution of oxygen，resulting in the associated leaching of gold. Taken together，the proper leaching temperature was optimized at 75 ℃ and L/S of 3∶1. Besides alkalinity，lowering solution potential could also avoid the oxidation of Na₂S. Because Sb⁵⁺ was relatively stable in alkaline environment，which restricted the leaching of antimony to a certain extent，resulting in incomplete removal in leaching residue. In theory，Mn reacted with oxygen preferentially than S²⁻，which effective prevented the oxidative hydrolysis of Na₂S to generate polysulfide and thiosulfate，and inhibited the dissolution of gold. The electrochemical and XPS analysis further revealed that Mn inhibitor had been oxidized to Mn²⁺，and gradually transformed into MnOOH and MnO（OH）₂ in solutions，which reduced the redox potential，effectively prevented the oxidation from S²⁻ to S₂O₃²⁻ and S_n²⁻，and alleviated associated leaching of gold. Under the optimal leaching conditions of Na₂S 100 g·L⁻¹+NaOH 100 g·L⁻¹，L/S of 3∶1，Mn addition content of 5%，the antimony leaching rate reached 93.3%，leaching at 75 ℃ for 30 min，and compared with no inhibitor，the associated-leaching rate of gold was reduced by 65.33%，the content of antimony in leaching residues was lowered down to 1.75%，and 96.01% gold was enriched in leaching residues，which effectively achieved the desired targets for antimony pre-removal and gold enrichment in leaching residue.

The feature size of micro-optical elements is typically on the order of microns or nanometers. Due to the development of micro- and nano-detection and test systems for industrial，commercial and civil applications in the last decade，researchers have conducted detailed and in-depth studies on increasingly miniaturized and integrated micro-optical components and systems，and the rapidly developing microelectronic manufacturing processes have contributed to the design，fabrication and application of micro-optical components. As a used basic optical element，optical grating consists of a large number of equal-width，equally spaced slits arranged periodically，and has four basic functions of dispersion，beam splitting，polarization and phase matching. Although the classical concept of diffraction grating is simple，its connotation is extremely rich. Over the years，gratings have been used for much more than their traditional applications，becoming irreplaceable and important components in many fields of technology. For example，gratings are used in integrated optics，optical holography，spectral analysis，fuzzy processing，digital-to-analog conversion correlation storage，beam coupling，beam sampling，beam splitting，data storage optical testing，bit-phase co-choking，mode-locking，signal processing，solar focused spatial light modulation，optical switching，diagnostic measurements，image recognition，and many more，while gratings continue to be used in new areas. With the development of science and technology，the requirements for grating are constantly improving. At present，many micro-opto-mechanical systems containing optical components are developing toward miniaturization，integration and arraying，so the size of many optical components is also reduced，such as micro-lens arrays，micro-nano gratings，etc. Therefore，the use of new materials for grating preparation and the development of new grating preparation techniques are crucial. Metallic glass has generated a great deal of research，while creating an increasing number of new opportunities for various basic research and commercial applications. Metallic glasses，also known as amorphous alloys，are new metallic materials in which atoms lose their long-range order and maintain their short-range order in three-dimensional space. The inherent structure and properties of metallic glasses further broaden their development field. Compared to crystalline materials，metallic glasses have a unique structure，which gives them many unique physical，chemical and mechanical properties and is one of the most active areas of research in the materials and physics communities today. Metallic glasses possess an amazing property that is not found in traditional metallic materials，which greatly compensates for the lack of mechanical properties of metallic glasses at room temperature and allows us to process this material more easily than traditional metals. This amazing property of metallic glass is its ability to soften after heating to a certain temperature，like glass or plastic，and is called the thermoplastic nature of metallic glass. The viscosity of metallic glass decreases significantly with increasing temperature，so that after heating to a certain temperature （also known as the supercooled liquid region），it can be molded at temperatures and stresses much lower than those required for conventional metal processing. In addition，metallic glass has no dislocations，grain boundaries and other crystalline defects，and its low coefficient of thermal expansion ensures excellent dimensional accuracy in thermoplastic molding，which makes it possible to produce precise microstructures on its surface by thermoplastic molding technology. At the same time，the researchers found that metallic glass has the advantages of high preparation efficiency （molding cycle in seconds，usually less than 30 s），good molding accuracy （dimensional error of about 2%），excellent surface quality （surface roughness of about 10 nm or less），simple process and low cost，etc.，so it has a very broad application prospect in the field of medicine，precision instruments and especially the emerging microelectromechanical systems. Based on this，metallic glasses have injected new blood into the preparation of gratings. Metallic glass has an exceptional surface finish after thermoplastic forming and is significantly more productive than conventional methods. Compared to crystalline glasses，metallic glasses have a smooth and glossy surface，which makes them promising for preparing grating structures with higher performance than common metals （e.g.，pure nickel，etc.）. Compared to conventional materials such as polydimethylsiloxane and polymethyl methacrylate，the unique mechanical and physical properties of metallic glasses improve the grating quality. In summary，the selection of materials and preparation processes for grating at the micro and nano scale are of particular importance as the quality requirements for optical devices continue to increase. Metallic glasses are ideal materials for grating preparation，but related research is still in its infancy. In this paper，the definition，classification and application of grating were reviewed. And the research status and unsolved scientific problems of the fabrication technology for traditional grating technology and amorphous alloy grating were presented，and the development opportunities and challenges of amorphous alloy grating in the future were prospected. The discussion in this paper provided a theoretical basis for micro-electro-mechanical （MEMS） system，which showed important theoretical and practical significance to promote the engineering application of amorphous alloy as a new material.

High-end titanium products metal titanium and chlorinated titanium dioxide have important strategic roles in aerospace，national defense industry，medical and health and other fields. TiCl₄ is the important intermediate raw material in the production of high-end titanium products. The boiling chlorination method has large scale and high efficiency，which is the main development direction for the preparation of TiCl₄，but its requirements for titanium raw materials are high （TiO₂>92%，CaO+MgO<1.5%）. Panxi titanium resources in China are abundant，but the content of calcium and magnesium impurities is high，and it is difficult to be used for boiling chlorination production. Efficiently removing calcium and magnesium impurities in China's Panxi titanium resources and meeting the requirements of boiling chlorination for raw materials is one of the important measures to promote the development of China's high-end titanium industry. At present，the research on calcium and magnesium removal of Panxi titanium resources mainly focuses on the deep impurity removal process of high calcium magnesium electric furnace titanium slag after titanium concentrate electric furnace smelting，which is complex in impurity removal process，serious environmental pollution，and difficult industrial application. From the perspective of mineral processing，this paper summarized the sorting methods，characteristics and applications of titanium concentrate，and proposes that the efficient sorting and impurity removal of titanium concentrate before smelting was conducive to improving the quality of titanium slag in electric furnace and effectively promoting the use of Panxi titanium resources in China to prepare high-quality boiling chlorinated charge. Magnetic separation and gravity concentration were commonly applied concentrating methods to obtain middles in the mineral processing. In the magnetic and gravity separation，the core technology footholds were：1） efficient grading and tail throwing；2） recovering fine-grained. The concentrate after pre-tailing and rough selection met the requirements of flotation for feed size and grade，reduced the amount of chemicals used in the flotation process，and avoided ore pulp modification. It was recommended to continue the particle size requirements when decalcifying calcium-magnesium silicate in titanium concentrate to avoid grinding operations and ore pulp modification. The ability of gravity separation to improve titanium grade was limited，and for the impurity removal before titanium concentrate smelted in the furnace，it was recommended to carry out strong magnetic separation again after magnetization roasting to remove entrained gangue in the re-concentration of titanium concentrate，which was expected to achieve a certain separation effect. The titanium middles needed to be cleaned to meet the final product demands. The electric separation and flotation were commonly employed in the concentrating process. The electric separation had strict requirements towards the particles size of feeding （>0.045 mm），which was not suitable for the domestic titanium ores. The development of flotation technology also contributed to the elimination of electric separation，leading to quite limited use of electric separation in industry. The current core technology of ilmenite flotation could be summarized as：1） mineral surface modification，2） development of new flotation agents. The mineral modification could be achieved by surface magnetization，microwave treatment and ultrasonic treatment. Although these methods were still researched in laboratories and not applied in large-scale industry，however，their good indication of separation still had certain practical significance. In particular，the development of new flotation agents had important guiding significance for the desiliconization and impurity removal before smelting of titanium. The above beneficiation process would make the product titanium concentrate have the characteristics of fine particle size and strong surface hydrophobicity. The difference in the type and activity of calcium-magnesium silicate and ilmenite surface localization ions played a key role in the separation. For the re-concentration of titanium concentrate，the key issues were to expand the difference between the surface properties of calcium-magnesium silicate and ilmenite，develop more selective silicate inhibitors，or enhance selective agglomeration behavior，so as to achieve efficient impurity removal. As a flotation product，titanium concentrate was adsorbed on the surface of the agent that would interfere with the subsequent separation. When re-entered into the solution environment，the surface hydrophobic groups might cause hydrophobic agglomeration，and some gangue minerals were encased inside，and the separation effect would be worse. It was recommended to make full use of the adsorbed agent on the surface of titanium concentrate in the selection process to prevent excessive addition of agent and strengthen the agglomeration behavior.

Deep eutectic solvents （DESs），which are prepared from quaternary ammonium salts mixed with hydrogen bond donors （HBD） such as amides，alcohols and carboxylic acids，have been developed as a promising solvent for organic synthesis，extraction and separation of metal and metal electrodeposition due to their excellent physicochemical properties. Additionally，they can selectively dissolve valuable metal oxide such as zinc oxide and cuprous oxide，but are unable to dissolve gangue ingredients including ferric oxide，calcium oxide and aluminium oxide，which offers an effective way for the recovery of zinc from zinc-containing secondary resources such as steelmaking dust，zinc slag，zinc smelting fume，etc. But so far，there are very few studies on the dissolution of metal oxides in deep eutectic solvents，and the relevant data are very scarce. Thus，it is of great interest to measure the solubility of metal oxides in deep eutectic solvents systematically and to study their thermodynamics of dissolution. Here，the solubility of main metal oxides that present in steel-making dust，including ZnO，Cu₂O，CuO，Ni₂O₃，Co₂O₃ and Fe₃O₄，in ChCl-urea DES was systematically measured by chemical method in the temperature range of 323~363 K. It was found that the solubility of these metal oxides in ChCl-urea DES varied widely. The solubilities of ZnO and Cu₂O in ChCl-urea ranged from 0.1906% to 37.2683% and from 0.0220% to 3.1470% respectively，which were much higher than those of CuO （0.0045%~0.1803%），Ni₂O₃ （0.0070%~0.2574%），Co₂O₃ （0.0034%~0.1174%） and Fe₃O₄ （0.007%~0.0465%） in ChCl-urea DES. This demonstrated that ZnO and Cu₂O had good solubility in ChCl-urea DES，while the rest of metal oxides were slightly soluble or insoluble in ChCl-urea DES，which was conducive to the selective dissolution of zinc from steel-making dust. With an increase of temperature from 323 to 363 K，the solubility of all metal oxides in ChCl-urea DES increased rapidly，but the degree of increase was different. The solubilities of ZnO and Cu₂O increased by about 196 times and 143 times，while the solubilities of CuO，Ni₂O₃ and Co₂O₃ only increased by 40，36，34 and 66 times. The solubility of each metal oxide in ChCl-urea DES was correlated with temperature，and it was found that the relationship between the solubility of ZnO and temperature was parabolic，and the solubilities of other oxides were linear with temperature. By fitting them，the empirical equations of solubility for these metal oxides were regressed. The phase equilibrium relationships between metallic oxide and ChCl-urea DES were established，and the activity coefficient，excess Gibbs free energy，excess enthalpy and excess entropy of different metal oxide in ChCl-urea DES were respectively calculated according to the rules of solubility equilibrium. The activity coefficients of all metal oxides in ChCl-urea were greater than 1 except for that of ZnO at higher temperature （≥343 K），indicating that ChCl-urea solution of metal oxides largely had a positive deviation from the ideal solution. At the same temperature，the activity coefficient of ZnO in ChCl-urea DES was much smaller than that of other metallic oxide in ChCl-urea DES，indicating that interaction between ZnO and ChCl-urea was much stronger than those of other metal oxides with ChCl-urea DES. For the same metal oxide，the activity coefficient decreased with the increase of temperature，which was because the solubility of metal oxides increased with the increase of temperature，and the interaction of metal oxides and low eutectic solvents was enhanced. Based on the relationship between excess Gibbs free energy and activity coefficient，excess Gibbs free energy of various metal oxides in ChCl-urea DES at different temperatures could be obtained by calculating. The excess Gibbs free energy of zinc oxide in ChCl-urea DES was far smaller than that of other metal oxides. Moreover，excess Gibbs free energy of each metal oxide decreased with the increase of temperature，and the relationship between them was linear. Through linear fitting of the relationship between excess Gibbs free energy and temperature，the excess entropy and excess enthalpy of metal oxides in ChCl-urea DES were obtained. It was found that the excess enthalpy of metal oxide in ChCl-urea DES was larger compared to that in aqueous solution and high temperature molten salt，which might be due to the different structure and properties of ChCl-urea DES and aqueous solutions （or high temperature molten salt）. In addition，the excess enthalpy and excess Gibbs free energy of ZnO in ChCl-urea were also lower than those of other metal oxides，which was ascribed to the smaller activity coefficient of ZnO in ChCl-urea. This result indicated that the property and behavior of the solution obtained by ZnO dissolving in ChCl-urea were closer to the ideal solution compared to those of the solution formed by other metal oxide dissolving in ChCl-urea. Meanwhile，excess entropy of ZnO in ChCl-urea was 79 J⋅mol⁻¹ and was relative lower，suggesting that the behavior of ChCl-urea solution containing ZnO was close to regular solution.

Electrolytic copper foil is one of the important materials for manufacturing copper clad laminate （CCL） and printed circuit board （PCB），it is also known as the "neural network" of electronic product signal and power transmission in the electronic industry. In recent years，due to the rapid development of science and technology in the downstream industry，higher requirements are put forward for the upstream electrolytic copper foil. Not only its demand is getting more and more，but also the quality requirements of copper foil are becoming higher and higher. At present，there are two kinds of methods for producing copper foil，one is calendering，and the other is electrolysis. Electrolytic production of copper foil is an efficient technology developed in recent years，whichhas the following two obvious advantages：highefficiency and low cost. The roll cathode withuniform speed and slow rotation is used to continuously produce electrolytic copper foils withcertain width. Withthe rapid development of China's electrolytic copper foil industry，the demand for cathode roller and the key equipment for producing copper foil are also increasing rapidly year by year. Cathode roller is the core and key part of electrolytic copper foil equipment and its quality determines the grade and quality of copper foil. There are two forming and manufacturing methods of "spinning" and "welding" for the titanium sleeve on the surface of the cathode roll. Althoughthe cathode roll produced by "welding" has many advantages，suchas low production cost，highproduction efficiency and the titanium sleeve is not affected by the diameter，while，the process also has some defects，that is，in the manufacturing process，a relatively obvious longitudinal weld will appear on the surface of the titanium sleeve，and this will cause a spot or bright band on the corresponding position of the copper foil surface in the subsequent production process，whichwill seriously reduce the production efficiency and affect the quality of copper foil. Therefore，the key technology of welding cathode roll is to use appropriate technical methods to control the microstructure in the weld zone （WZ） and its heat affected zone （HAZ）. In this study，TA1 was used as the material，and TA1 plate was welded by manual TIG welding，after welding，vacuum annealing was carried out at the temperature of 550~700 ℃ for 2 hto refine the grain in the weld zone and reduce the difference between the weld zone and the base metal，and sand blasting was primarily conducted after vacuum heat treatment to further refine the grain size in the weld area，and it could provide technical basis for the "welding" manufacturing of titanium sleeve of cathode roller. DMI-3000 m optical microscope （OM） was used to observe the microstructure of the substrate and eacharea after welding. The results showed that the base metal structure was mainly equiaxed at room temperature，the grain was fine and uniform，whichwas a standard equiaxed crystal. The microstructure of weld zone was mainly composed of partial columnar crystals and single fine needle secondary crystals α phase. The microstructure of the heat affected zone was coarse α phase and partially acicular secondary α phase. After welding，the microstructure of the weld zone was very different from that of the base metal，whichwas mainly reflected in：there were many irregular cross flake and acicular structures in the weld zone. This was because a lot of heat is generated in the welding process，and grain coarsening would occur near the fusion line. At the same time，due to the different influence degree of heat input，the microstructure of weld zone was mainly composed of coarsened columnar β phase along witha little acicular α phase. The microstructure of the heat affected zone was coarse α phase and partial acicular secondary α phase. In general，withthe increase of annealing temperature，the microstructure of eachregion of the welding had been refined to a certain extent. And it was found that annealing at 650 ℃ could get the best effect. At the same time，after heat treatment and sand blasting，the microstructure of the weld zone had been refined to a certain extent. The reason was that sandblasting provides highstrain conditions for the surface of the sample，resulting in a large number of dislocations on the surface. Dislocation density increased withthe increase of deformation，and high-density dislocations gradually formed dislocation walls，that was，sub grain boundaries. As the strain continued to increase，new dislocations were continuously generated，and then evolved into new sub-grain boundaries. At the same time，the initially formed sub-grain boundaries could evolve into grain boundaries，so that the grains were refined. Therefore，the microstructure of eachwelding area had been refined to a certain extent after sandblasting，thus further reduced the difference between the microstructure of the weld area and that of the substrate.

The microstructure and properties of Al-Zn-Mg-Cu-Zr aluminum alloy after deformation were mainly investigated，but the microstructure and properties of cast aluminum alloy were less reported. Appropriate microalloying could effectively enhance the microstructure and process properties of casting alloys，reduce casting defects and improve alloy properties，which can provide reference for the ingots of this series of deformed aluminum alloys. Rare earth elements were the most effective additive elements to optimize the comprehensive properties of ultra-high strength aluminum alloys. The interaction between rare earth (RE) elements and matrix elements to form and bulk compounds （AlZnMgCuRE）. These dispersed phases uniformly distributed in the matrix can strongly pin dislocations and subgrain boundaries，which could significantly inhibit recrystallization，thus enhancing the stress corrosion resistance，exfoliation corrosion resistance and fracture toughness of the alloy. Rare earth Nd was rarely applied in Al-Zn-Mg-Cu-Zr series aluminum alloys，most of be illustrated by application of 2xxx aluminum alloys and Al-Si series alloys. The addition of Nd could change the morphology and size of the as-cast primary phase simultaneously，improve the heat resistance of aluminum alloys，which could provide a basis for exploring and developing new Al-Zn-Mg-Cu-Zr high strength aluminum alloys. Due to the negative effect of excessive rare earth content on the structure and properties of the alloy，the usual addition amount was 0.2%~0.4%. Optical microscope （OM），scanning electron microscope （SEM），energy spectrum analysis （EDS），X-ray diffraction （XRD） and Brinell hardness test were used to investigate the effect of rare earth Nd on the microstructure of the as-cast alloy，the variety and morphology of the non-equilibrium eutectic phase，the element distribution and the mechanical properties. Then the optimal addition amount of rare earth was selected. The results showed that the microstructure of as-cast alloy was typical dendritic crystal，which was mainly composed of α-Al matrix，lamellar Mg（Al，Cu，Zn）₂，η（MgZn₂），a small amount of light gray θ（Al₂Cu） phase and irregular block Al₈Cu₄Nd phase；Nd element had a better effect on inhibiting dendrite growth and refining grains，and 0.2% （mass fraction） Nd had the optimum effect of refining and comprehensive performance. The eutectic structure of 0.2% Nd alloy became discontinuous and thin，the dendrite spacing and the non-equilibrium eutectic phase at the crystal boundary were also relatively reduced. However，with the continuous increase of the addition amount，the grains tended to grow again，and the refinement effect of the alloy was relatively weakened. This was mainly due to the high chemical activity of rare earth element Nd. During the process of alloy casting and solidification，the limitation of solidification diffusion kinetic conditions makes the diffusion rate larger，composition segregation occurred at the front of the solid/liquid interface，and the solute redistribution generated in the process of crystal nucleation and growth，which changed the composition undercooling zone，thus inhibiting the growth of dendrite during solidification of the alloy. When the addition amount of rare earth Nd exceeded a certain limit，a large number of Nd intermetallic compounds would be formed and coexist at the grain boundary，which reduced the solidification rate，coarsens the grain boundary，weakened the effect of Nd atoms on the supercooling of alloy composition，and the dendrite arm spacing got increased. Compared with the alloy without Nd，the average spacing and average grain size of the secondary dendrite spacing of the alloy with 0.2% Nd decreased by 48.1% （53.24 μm） and 50.5% （258.98 μm），respectively. The addition of rare earth Nd was beneficial to reduce the segregation of alloy elements，especially Cu element. This phenomenon was mainly that grain refinement，therefore the segregation distance was shortened，easily diffusion homogenization，thereby reducing intracrystalline segregation. With the continuous addition of Nd content，the increase of Brinell hardness remained in a relatively stable state，this phenomenon indicated that the alloy with Nd element had good uniformity of structure. Brinell hardness of the sample with 0.2% Nd reached the maximum value of HBW 105.2，the tensile strength reaches the maximum value of 163 MPa，and the elongation reaches 2.5%，which were 44.9%，34.3% and 44% higher respectively than alloy without Nd. With the addition amount of Nd further increased，Brinell hardness of different alloys showed a slow decreasing trend，the minimum Brinell hardness value of the alloy with 0.4% Nd reduced to HBW 99.8，the tensile strength reached the minimum value of 127 MPa，which were still 41.9% and 15.7% higher respectively than alloy without Nd. It was mainly that the precipitation of a small rare earth phase during the melt solidification，which could be used as the heterogeneous nucleation substrate of α-Al matrix，so as to improve the nucleation rate，refine the grain and improve Brinell hardness. In the subsequent studies，it should be noted that the rare earth phase with high melting point would be formed after the addition of rare earth Nd. The formation of high melting point phase could enhance the pinning effect on the grain boundary movement. At the same time，the strain field around the precipitated second phase and the precipitated second phase could effectively hinder the movement of dislocation. The hindrance effect depended on the type，size and dispersion of precipitates. The more obvious the hindrance effect of dislocation movement，the higher the strength of the alloy，which provided a direction for further research.