With the development of new energy industry,the development and utilization of lithium resources in salt lake brines have attracted more attention.In this context,the technology of extracting li-thium from salt lake brines has also developed rapidly.This paper analyzes the development stage of the technology of extracting lithium from salt lake brines in China and its future development direction by using patent technology life cycle method.The results show that among traditional methods,the membrane method has become mature and the substitution of the old technologies with the new ones is obvious;adsorption and extraction methods are still in the technology growth stage with a number of technological innovations.In recent years,electrochemical lithium extraction technology has developed rapidly for its advantages of high selectivity,low cost,and eco-friendly protection,showing that it is a promising method for lithium extraction from salt lake brines.

(V,Cr,W)C composite powders were prepared by carbothermal reduction method using Cr₂O₃,WO₃,V₂O₅,and carbon black as raw materials at 1500℃for 2 h.The phase ingredients and microstructure of(V,Cr,W)C composite powders were characterized by XRD and SEM,and the effects of adding method and content of the composite powders on the microstructure and mechanical properties of WC-11Ni cemented carbides were investigated.The results show that the mechanical properties of the alloy are significantly improved by the addition of(V,Cr,W)C composite powders,and its flexural strength,Vickers hardness,and fracture toughness are increased by 19.97%,19.61%,and 12.18%,respectively,compared with those of the specimens without composite powders.The properties of the alloy with(V,Cr,W)C composite powders are better than those with(V,Cr)C composite powders and with WC+Cr₃C₂hybrid powders.In addition,the flexural strength,Vickers hardness,and fracture toughness of the alloy increase at first and then decrease with the increase of the addition of the(V,Cr,W)C composite powders.When the addition of the(V,Cr,W)C composite powders is 0.6%,the flexural strength,Vickers hardness,and fracture toughness of the alloy reach the maximum values of 2835 MPa,1671 MPa,and 15.1 MPa·m^1/2.

The catalyst of molybdenum oxide-loaded monazite was prepared by impregnation method,and tests for its characterization and NH₃-SCR denitration performance were carried out.The results show that the NO conversion rate of the composite catalyst with Mo/Ce molar ratio of 0.3 reaches 75%at the denitration reaction temperature of 400℃.Monazite increases the specific surface area of the catalyst.The loaded metal oxides are uniformly dispersed on the monazite surface,resulting in the coexistence of Ce³⁺/Ce⁴⁺and Mo⁵⁺/Mo⁶⁺and promoting electron transfer to generate oxygen vacancy and unsaturated chemical bonds,which is in favor of the increase of the active site on the monazite surface.Compared with pure monazite,the redox property and the adsorption and activation capacity of NH₃of the composite catalyst have been improved mainly in the high temperature range,with a relatively small improvement in the denitration efficiency in the low temperature section.

The liquidus temperature of ScF₃-LiF molten salt was measured by step cooling curve method.The solubility of Sc₂O₃in ScF₃-LiF molten salt was measured by the isothermal saturation method,and the effects of temperature and ScF₃content were studied.The dissolution mechanism of Sc₂O₃in ScF₃-LiF molten salt was analyzed by X-ray diffraction.The results show that the liquidus temperature of ScF₃-LiF molten salt rises with the increase of ScF₃content,while it decreases with the addition of Sc₂O₃.The dissolution of Sc₂O₃in ScF₃-LiF molten salt is mainly chemical dissolution,the dissolution equilibrium time is about 2 h,and its solubility increases with the increase of temperature and ScF₃content.

Taking X100 pipeline steel as the research object,the test steel with various amounts of Ce was smelted in a vacuum induction furnace under laboratory conditions.The effects of Ce on microstructure and corrosion resistance of X100 pipeline steel were studied by scanning electron microscope,Zeiss metallographic microscope,electrochemical workstation and X-ray diffractometer.The results show that the addition of Ce transforms MnS and Mn-Si-Al-O inclusions in X100 steel into Ce_xO_yand Mn-Si-Al-O-Ce inclusions,and the size increases from about 4μm to about 10μm.Ce has obvious refining effect on the microstructure of X100 test steel,representing that in the range of 0~0.0049%,the microstructure of the test steel is gradually refined with the increase of Ce content.The addition of Ce can also improve the corrosion potential and lower the corrosion current density of the test steel.Under the condition of immersion in 3.5%NaCl solution for 28 d,corrosion current density of the test steel decreases from 4.6347 mA/cm² without Ce addition to 3.7784 mA/cm² with Ce content of 0.0049%,and the test steel with Ce content of 0.0049%shows better corrosion resistance.In addition,the addition of Ce can effectively increase the content ofα-FeOOH and Fe₃O₄in the corrosion product and enhance the protection of the steel matrix,which is conducive to improving the corrosion resistance of the test steel.

The magnetic properties and microstructure of sintered Nd-Fe-B magnets co-doped with Ga,Al,Cu,and Zr were studied,and coercivity of the magnets was regulated by tempering process.The results show that when the first annealing is 900℃×150 min and the second annealing is 500℃×180 min,the magnet coercivity H_cjgreatly increases from 14.33 kOe in the sintered state to 19.86 kOe in the second annealing state,which is a increase of 38.6%;rectangularity H_k/H_cjincreases from 0.86 to 0.97;remanence B_rdecreases slightly from 13.51 kGs in the sintered state to 13.46 kGs in the second annealing state;the distribution of RE-rich phase becomes more continuous and obvious.The research analysis shows that the reason why the coercivity greatly increases is that Ga doped in the sintered Nd-Fe-B magnets containing small amounts of Nd-rich phase and B-poor phase changes the wettability of intergranular phase and reduces Fe content in the RE-rich phase.The study lays a solid theoretical foundation for the industrialization of heavy rare earth-free sintered Nd-Fe-B magnets with high coercivity and high remanence.

Sm₂Fe₁₇ZrNb_0.4Cu_0.2B_0.2amorphous alloy ribbons were prepared by fast quenching at the speed of 40 m/s in a high vacuum arc melting and single-roll rotary quenching integrated furnace.In order to realize the explosive nucleation of amorphous alloy ribbons at relatively low crystallization temperature,and refine grains and together improve the uniformity of microstructure,it is necessary to improve the order degree of atoms before crystallization.Therefore,the amorphous alloy ribbons were pre-annealed at 500℃for different time to study the crystallization evolution of the amorphous alloy with different pre-annealing time.The results analyzed by X-ray diffractometer(XRD)and high-resolution transmission microscope(HRTEM)show that long-term pre-annealing treatment has a great influence on the precipitation ofα-Fe phase.When the pre-annealing temperature is 500°C,the pre-annealing time should not exceed 90 min.Too long pre-annealing time leads to the early precipitation of crystal phase and uneven crystallization microstructure.

The effect law of magnetron sputtering process parameters on phase,microstructure,mechanical properties,and adhesion of TiAlN films were analyzed by XRD,SEM,nanoindenter,and nano-scratch tester.The results show that the generated phases of all samples are face-centered cubic TiAlN and preferentially grow on(111)crystal plane.The close-packed triangular pyramid-like grains are formed on the surface of the films.By selecting hardness and adhesion to evaluate the TiAlN films,it is found that the optimal process parameters of hardness and adhesion are substrate bias voltage of-100 V,working air pressure of 0.3 Pa,sputtering current of 8 A,and nitrogen flow of 40 sccm through orthogonal experiments.

Ti(C,N)-based cermets were prepared with mechanically alloyed Ni-Ti-Cr solid solution as the binder.The effects of solid solution with different Cr contents on microstructure,mechanical properties and oxidation behavior of the cermets were studied.The results show that with the increase of Cr content,the particle size of the cermets decreases at first and then increases,while bending strength,fracture toughness and hardness increase at first and then decrease.When the mass ratio of Ni,Ti and Cr is 91∶3∶6,the cermets have the best comprehensive performance:The bending strength,fracture toughness and hardness reach 2120.3 MPa,15.41 MPa·m^1/2and 88.9 HRA,respectively;the oxide film is dense,and the oxidation weight gain and peeling of the oxide film are inconspicuous.After oxidation for 60 h,the outer oxide film of the cermets is dominated by NiO,and TiO₂is mainly embedded in the NiO grain boundary.The loose TiO₂layer is formed inwardly,and the Cr element is enriched further inwardly,forming dense NiO and NiCr₂O₄layer that could effectively absorb oxygen atoms,hinder further oxidation,and play a role in connecting and transiting between layers.During cyclic oxidation,the peeling of the oxide film of the cermets is a cyclic process from NiO layer to TiO₂layer.

To improve the corrosion resistance and conductivity of titanium bipolar plates in proton exchange membrane(PEM) water electrolyzer, a carbon-doped titanium nitride(C-TiN) composite protective coating was prepared on the surface of the titanium substrate by electrophoretic deposition-heat treatment, and its electrochemical corrosion performance was tested in the solution containing 0.5 mol/L H₂SO₄and 5 mg/L F-,which simulates the anode environment of PEM water electrolyzer.The results show that electrophoretic deposition and heat treatment improve the connectivity of titanium nitride nano-particles, enhance the adhesion between the coating and the substrate, and realize the rapid transfer of electrons in electroactive materials.The conductivity and corrosion resistance of the carbon-doped TiN coating prepared at 400 ℃ receive great promotion.Compared with the untreated sample, the contact resistance of the sample plated with C-TiN-400 ℃ coating can reach 2.25 mΩ·cm² at the pressure of 146.3 N/cm².