The effect of Al₂O₃doping on the electrochemical corrosion resistance of molybdenum alloys in 3.5%NaCl solution was studied,and the corrosion mechanism of the alloys was analyzed.The results show that the corrosion resistance of Mo-Al₂O₃alloys is significantly better than that of pure molybdenum,and it increases at first and then decreases with the increase of Al₂O₃content.During the corrosion process,Cl^-is preferentially adsorbed on the defect positions of the molybdenum alloy oxide film to form pitting.With the increase of potential,the pitting expands along the grain boundary to become corrosion grooves.Al₂O₃can refine the molybdenum grains to promote the formation of a dense oxide film of molybdenum alloys which is less easily prone to pitting,thereby improving the corrosion resistance of the molybdenum alloys.However,when the volume fraction of Al₂O₃in molybdenum alloys reaches 1.6%,the Al₂O₃particles agglomerate and grow larger,which destroys the integrity of the oxide film of the molybdenum alloy and weakens their protection of the alloy matrix,resulting in a decrease in the corrosion resis-tance of the molybdenum alloy.

LiNbOpolycrystal powder was prepared from high-purity niobium pentoxide and high-purity lithium carbonate by proportionally mixing,charging and sintering.And the control of the preparation process was reflected by the decrement rate of the components.The results show that the increase of sintering temperature and holding time can promote the increase of particle size of LiNbOpolycrystal powder.The particle size distribution of LiNbOpolycrystal powder prepared by two-stage sintering of 790~850℃×3.5 h and 1050~1100℃×4 h is uniform with D50 of 18.10μm,which is suitable for LiNbOsingle crystal production.

To eliminate theβspots in Ti-1 Al-8 V-5 Fe(Ti185)alloy produced by conventional casting process,the large-particle-size Ti185 alloy powder was formed by selective laser melting,and the selective laser melting Ti185 alloy was optimized by remelting process.The microstructure and mechanical properties of the top,middle and bottom positions of the formed sample before and after remelting were analyzed.The results show that macroscopic cracks exist in the Ti185 sample formed by selective laser melting,and the remelting process can effectively suppress the initiation of the cracks.The microstructures of the formed samples by selective laser melting and remelting optimization are all composed of equiaxedβphase,and subcrystalline microstructure exists inside the equiaxed grains.The maximum compressive strength of the formed sample by selective laser melting which is optimized by remelting is 2127±120 MPa,and its fracture strain is 21%±5%,which shows a decrease in compression performance compared with the sample before remelting.

Based on Materials Studio software,a simulation analysis of the growth mechanism of TiC cera-mic particles was conducted and the morphology of the particles was reasonably predicted.To verify the accuracy of simulation results,(Ti+C)/Ni60 laser cladding layer was prepared on H13 steel substrate.The morphology of TiC and the phase and hardness of the coating were analyzed by scanning electron microscope(SEM),energy dispersive spectroscope(EDS),X-ray diffractometer(XRD),and micro-hardness tester.The results show that the morphology of TiC particles obtained by simulation prediction has high consistency with the one obtained by experiments.The plane shapes of TiC particles are usually quadrila-teral,such as square and rhombus.In the cladding process,the main causes for the inconsistency between the predicted and actual morphologies include the cladding environment,phase growth inhibition,and solid-liquid phase interaction.The TiC ceramic particles prepared in-situ are evenly distributed in the coating,and the microhardness of the coating is significantly improved.

The microstructure and mechanical properties of B2-type as-cast Zr₄₆Co₄₆Cu₈,Zr₄₅Co₄₅Cu₁₀and Zr₄₄Co₄₄Cu₁₂alloys were studied by X-ray diffractometer,optical microscope,electro-mechanical universal testing machine,and scanning electron microscope.The results show that the Zr-Co-Cu alloys are mainly composed of the B2-ZrCo phase and the secondary phase Co₂Zr,and the content of the Co₂Zr phase increases with the increase of Cu content.Part of the Co₂Zr phase precipitates along the grain boundary or inside the equiaxed B2 phase particles.Also with the increase of Cu content,both the yield strength and elastic limit of the material increase.The higher strength of Zr₄₅Co₄₅Cu₁₀and Zr₄₄Co₄₄Cu₁₂alloys is attributed to the grain refinement of the B2 phase and the strengthening effect of the secondary phase Co₂Zr.The larger toughness values of Zr₄₆Co₄₆Cu₈and Zr₄₅Co₄₅Cu₁₀alloys indicate that these two alloys are safe and reliable in practical application.The fracture mechanism of Zr₄₆Co₄₆Cu₈and Zr₄₅Co₄₅Cu₁₀alloys is mainly ductile fracture,while the fracture mechanism of Zr₄₄Co₄₄Cu₁₂alloy is mainly ductile fracture supplemented by intergranular fracture.

The piezoelectric material K_0.5Na_0.5NbO₃(KNN)surface-modified nickel-rich cathode material LiNi_0.83Co_0.12Mn_0.05O₂was prepared by in-situ coating,and the electrochemical performance of the as-prepared material was also studied.The XRD pattern shows that the sample modified with KNN does not change the layered structure of the nickel-rich cathode material.The XRD refinement results also confirm the existence of KNN by which the crystal structure of the bulk material is not affected.Meanwhile,the EDS Mapping analysis demonstrates that KNN has successfully coated the surface of the nickel-rich ca-thode material.Based on the measured electrochemical performance,in the voltage range of 2.8~4.3 V,the initial discharge specific capacity of the modified sample KNN@NCM83 increases at 0.1 C rate.More-over,after 100 cycles,the modified sample still maintains a discharge specific capacity of 157.8 mA·h/g with a capacity retention rate of 82.3%,while the pristine sample NCM83 only maintains a discharge specific capacity of 133.6 mA·h/g with a capacity retention rate of 75.2%.Compared with the pristine sample,KNN@NCM83 presents a better rate performance and particularly,its specific discharge capacity reaches 155.6 mA·h/g and 148.6 mA·h/g respectively at 5 C and 10 C.This indicates that KNN could effectively improve the Li⁺transmission efficiency of the nickel-rich cathode material,which could improve the rate performance of the sample in turn.The EIS test results show that the solid electrolyte interface film(CEI film)generated on the surface of KNN@NCM83 electrode after cycling is thin and stable with low charge transfer resistance,which fully demonstrates that the modified sample has a stable structure and good reversibility.

WC-7%Co coarse-grained cemented carbide was prepared with two groups of ultra-coarse WC powders(Fsss>25μm)of which the particle agglomeration degree is different.The soft agglomerated particles of raw WC powders are dispersed by ball milling,while the hard ones are left in the alloy.The effect of raw WC agglomeration degree on the properties of coarse-grained cemented carbide was studied by metallographic microstructure observation and physical and mechanical properties test of the alloy.The results show that the agglomeration degree of raw WC powders has a great influence on the physical and mechanical properties of the alloy.The coercivity,hardness,average grain size and abrasive wear value of the alloys prepared under the same process conditions are similar.However,the alloy without WC aggregation in the metallographic microstructure performs better in bending strength and impact toughness,and the fracture morphology shows that the alloy has better toughness.

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The extraction of vanadium from stone coal was carried out by the process of acid mixing pelleting,high temperature curing and column leaching.Also,the study discussed the leaching effect of vanadium from raw ore affected by process conditions such as the amount of sulfuric acid,the amount of water supplement for curing,the binder dosage,the curing temperature,the curing time,the particle size of the cured material and the spraying intensity.The results show that the leaching rate is 76.99%when the conditions of the process are as follows:The particle size of the raw ore is less than 12 mm;the water content of the raw ore is 10%;the amount of sulfuric acid is 20%;the binder dosage is 0.05%;the curing temperature is 135 C;the curing time is 10 h;the particle size of the cured material is less than 8 cm;the liquid-solid ratio of leaching section is 1.5:1;the spraying intensity is 15 L/(m²·h).After the leaching residue is washed four times(the liquid-solid ratio of washing section is 1.5:1),the leaching rate of vanadium can be increased to 87.48%,and the content of V₂O₅,in the tailings can be reduced to 0.11%.The research can provide important reference for the industrial production of the heap-leaching of vanadium ore.

The technology of recovering beryllium and useful resources from the waste slag produced in the melting and casting process of beryllium-copper alloy was studied.Using ESR waste slag as a covering agent,beryllium-copper waste slag was refined and purified in a vacuum induction furnace under the protection of a molten slag layer.The Yuanbao ingots obtained after refining and casting can be used as interalloys for producing beryllium-copper alloy ingots to replace expensive beryllium-copper master alloys.The recovered ESR waste slag can be recycled for the recovery treatment of beryllium-copper waste slag,and can also be used as a flux for the manufacture of ceramics,glass,etc.after impurity removal and purification.The experimental results show that adjusting the slag viscosity to about 0.09 Pa·s under the optimal mass ratio of ESR waste slag to CaF₂ is beneficial to the improvement of metal yield and Be yield.When the vacuum degree is below 0.07 MPa,the Yuanbao ingots with no pores and uniform internal microstructure are obtained by vacuum refining.The successful research and development of this technology not only enables the comprehensive utilization of beryllium-copper waste slag as resources,turns waste into treasure,greatly reduces production costs and increases metal recovery rate,but also solves the environmental problems caused by long-term storage of beryllium-copper waste slag.