In order to study the influence of electric field on anode gas holdup in rare earth electrolytic cell,the FLUENT software secondary development function was used to build the electric model of rare earth electrolytic cell.And then numerical simulation was carried out of the correlation between the electric field and the gas holdup in the electrolytic cell.The distribution of the anode gas holdup with or without the electric field was compared.It is found that the gas holdup of no electric field loaded model is lower than that of electric field loaded model at the same anode height.The difference of anode gas holdup caused by electric field loading is the largest when the anode height is 0.250 m,and then the difference decreases with the increase of anode height.The results are more coincident with the actual operation situation of electrolytic cell,providing a theoretical basis for the further development of large rare earth electrolytic cell.

Vanadium slag was subjected to pelleting with NaOH,roasting,leaching with water and filtering to obtain strongly basic vanadium slag extracting solution with the pH value of 13.1.A weakly basic anionic exchange resin B containing amino functional group[-CH2 NH（CH2 CH2 NH）nH]＋was directly added into the extracting solution for selective adsorption experiments.The adsorption behavior of Cr ions in the extracting solution was studied.The results show that when the absorption temperature is 20℃,30℃and 40℃,Cr adsorption equilibrium time is 24 h,7 hand 7 h,respectively.When the adsorption temperature is raised from 20 ℃to 30 ℃,Cr adsorption amount dramatically increases.The optimal adsorption temperature is 30℃and Cr equilibrium adsorption amount is 217 mg/g in this case.Cr ion adsorption follows pseudo-first-order adsorption kinetic model.When the adsorption temperature is raised from 20 ℃to 30 ℃,Cr adsorption rate increases by about 2 times.The internal diffusion of Cr ions in the resin pores is the controlling step of adsorption rate.Cr adsorption amount increases with the initial Cr concentration increasing.Thermodynamically,Cr ion adsorption is consistent with the Langmuir model,the Freundlich model and the DKR model,but it is closest to the Freundlich model.Based on the DKR model,the apparent adsorption energy of Cr ions is 5 000 J/mol,7 071 J/mol and 7 071 J/mol,respectively at the absorption temperature of 20 ℃,30 ℃ and 40 ℃.

Co-9 Al-9 W-0.1 Balloy was directionally solidified at different withdrawing rate,and its solidified microstructure was observed and the grain growth orientation was investigated by electron backscatter diffraction.With the withdrawing rate of 20 mm/h and 60 mm/h,the solid-liquid interface fronts are plane and cellular,respectively,and the growth orientation is both close to the〈101〉direction.With withdrawing rate increasing,the solid-liquid interface front changes into dendrites.When the withdrawing rate is 180 mm/h,the growth orientation is〈013〉direction.With the withdrawing rate of 360 mm/h,the grain growth orientation deviated from 〈101〉by about 30°.Co-9 Al-9 Walloy has a preferred orientation of〈001〉after a period of competition growth during directional solidification at 180 mm/h withdrawing rate.Borides can strengthen grain boundaries and the absence of borides results in the poorer creep strength of Co-9 Al-9 W alloy,compared with Co-9 Al-9 W-0.1 Balloy directionally solidified at the same withdrawing rate.Co-9 Al-9 W-0.1 B alloy directionally solidified at 180 mm/h withdrawing rate has columnar grains and higher creep strength than Co-9 Al-9 W-0.1 Balloy with equiaxed grains.

In order to improve the high temperature oxidation resistance of carbon/carbon composite material,the MoSi2 coating was prepared by electrophoretic deposition of MoSi2 powder with a particle size of about 13μm on the surface of carbon/carbon composite material cylinder with diameter of 30 mm and thickness of 5 mm in ethanol solution at room temperature,and then sintering in 800℃argon atmosphere.The optimal conditions for electrophoretic deposition are as follows：electrophoretic deposition voltage of 95 V,electrode gap of 2 cm and electrophoretic deposition time of 5 min.Under such conditions,the MoSi2 coating surface is flat and smooth with a weight of 65.3 mg,an average thickness of 46μm and an average binding strength of 23.9 MPa.The MoSi2 coating prepared under the optimal electrophoretic deposition conditions can reduce the static oxidation rate of carbon/carbon composite material in air at 1 500 ℃from 0.82%/min to 0.49%/min,and the weight loss rate of the sample decreases from 63%to 39% within 80 min.Applying a layer of Si-Al-O composite oxide ceramic coating on the surface of MoSi2 coating can further reduce the sample oxidation rate and weight loss rate to 0.15%/min and 11%,respectively.The dual coating is more effective than the addition of single coating in terms of reduction of substrate weight loss rate,so the dual coating may have some synergistic effects on inhibition of substrate oxidation.

The drilling axial force and drilling torque during drilling machining of molybdenum alloys with different drilling parameters were measured by experiments.The effect of feed speed and spindle speed on drilling axial force and drilling torque was analyzed.The results indicate that with constant feed rate and changed spindle speed,the drilling axial force slightly decreases with the increase of spindle speed,and the drilling torque also decreases with the increase of spindle speed.With constant spindle speed and changed feed rate,both drilling axial force and drilling torque increase with feed rate increasing.Feed rate has more significant influence on drilling axial force and drilling torque than spindle speed.

AlSi7Mg0.3 alloy was modified with rare earth Y,and the influences of rare earth Y on the morphology and mechanical properties of AlSi7Mg（0.3） alloy were researched by metallographic microscope,X-ray diffraction and tensile tests.The results show that a small addition of rare earth Y can refine eutectic silicon,and Si phase obviously changes from plate shape to needle shape and small granular shape.The elongation of the alloy increases gradually with the increase of Y content.When 0.06% Y is added,the elongation of AlSi7Mg（0.3） alloy can reach the maximun value of 12.5%.

Spindle shaped TiO2 hierarchical structural material was successfully synthesized via a solvothermal method,and then its morphology and microstructure were characterized and analyzed by SEM and XRD.The effects of hydrothermal temperature and acetic acid dosage on TiO2 sample were investigated as well as photocatalytic performance of the sample.The results show that the obtained TiO2 hierarchical structural material is composed of anatase phase,having nanocrystalline self-assembled spindle structure.The hydrothermal temperature and acetic acid dosage have little effect on TiO2 morphology,while they have an effect on TiO2 size.The photocatalytic performance of TiO2 sample was evaluated with methyl orange as the simulated contaminant.TiO2 sample shows good photocatalytic activity under ultraviolet light irradiation.

TiO2-SiO2 nanometer composite oxide was prepared by gaseous detonation with H2 and O2 premixed gas as the explosion source,and TiCl4 and SiCl4 as the precursor.The influence of precursor Ti/Si ratio on the detonation product was investigated.Crystal structure,morphology and chemical composition of the detonation product were analyzed by XRD,TEM and FTIR.The resluts show that TiO2 is a mixture crystal of ruble and anatase in TiO2-SiO2 nanometer composite oxide,and SiO2 is amorphous.There is Ti—O—Si bond in TiO2-SiO2 nanometer composite oxide particles.amorphous adheres to the exterior of the crystalline TiO2 in the obtained TiO2-SiO2 composite structure.And the composite structure changes with precursor Ti/Si ratio.

The effect of different heat treatment systems on microstructure and mechanical properties of a new type of Ti-3 Zr-2 Sn-3 Mo-25 Nb medical titanium alloy was analyzed.The results show that the alloy is composed of primaryαphase andβphase after solution treatment in（α＋β）two-phase field.Primaryαphase has short and fine size,precipitated inside the grains and around the grain boundary in granular form.As the rise of the solution treatment temperature,the volume fraction of primaryαphases is decreasing and the volume fraction ofβphases is increasing.The alloy is composed of singleβphase after solution treatment inβfield.As the rise of the solution treatment temperature,the size ofβphase grains is increasing and it is about 25μm.Acicularαphase with fine size and cross arrangement is precipitated in theβphase matrix after solution treatment in（α＋β）two-phase field plus aging treatment.Fine acicularαphase with different sizes is precipitated around grain boundary and inside the grains after solution treatment inβfield plus aging treatment.Theαphase precipitated around grain boundary has a definite orientation.Theαphase precipitated inside the grains is crisscrossed and its size is nonuniform.The alloy obtains a medium strength and better ductility after solution treatment.As the rise of solution treatment temperature,tensile strength and yield strength of the alloy are decreasing,while the ductility and elasticity modulus are increasing.The difference value between tensile strength and yield strength（Rm-Rp0.2）is greater after solution treatment in（α＋β）field than that after solution treatment inβfield.Strength increment of the alloy is higher after solution treatment in（α＋β）field plus aging treatment than that after solution treatment inβfield plus aging treatment.Under the same aging conditions and as the rise of solution treatment temperature,the strength and modulus of the alloy are decreasing,and the elongation rate remains unchanged.The elastic modulus of the alloy reaches the minimum value（E=64 GPa）after solution treatment（780 ℃,30 min,AC）and aging treatment（480 ℃,6 h,AC）,and this value is closest to the elastic modulus of human natural bone and other hard tissues.

The sintered samples of Ti（C,N）-based cermets were prepared by vacuum sintering at different heating temperature for different holding time.The grain size was measured with metallographic quantitative method.The grain growth kinetic model of Ti（C,N）-based cermets during sintering was established based on Sellars model and Anelli model,and the grain growth kinetic equation was determined by nonlinear regression analysis of the experimental data.The results show that when the temperature is lower than1 300 ℃,the average grain size of Ti（C,N）-based cermets increases with the increase of the holding time,but the growth rate is slow.When the temperature is higher than 1 300℃,the grain growth rate rapidly increases at first to reach the maximum value and then decreases.The crystal grain growth apparent activation energy of Ti（C,N）-based cermets during sintering is 493.67 kJ/mol,and the kinetic equation is d^2.82=d^2.820＋2.75×10^23 t^ 1.373 exp[-493 670/（RT）].