Phosphorus removal from sodium tungstate solution is very important to produce qualified ammonium paratungstate products.Using industrial sodium tungstate solution as raw material,the effects of dephosphorizing agent dosage,residual alkali concentration and feeding methods on dephosphorization of sodium tungstate solution were studied.The results show that the dephosphorization rate of sodium tungstate solution is over 98%when the dephosphorizing agent is 2 times the theoretical amount,the residual alkali concentration is 15 g/L,the reaction temperature is 75℃and the reaction time is 1.5 h.In addition,the test results also show that the crystallization mother liquor can be mixed with sodium tungstate solution,and the residual alkali contained in the mother liquor can be used to adjust the pH value of the phosphorus removal system to reduce the consumption of alkali.The experimental results can provide theoretical guidance for optimizing technological parameters of deep dephosphorization of sodium tungstate solution in industry.

P-tert-butyl calix[8]arene phosphate(abbreviated as TPA)was synthesized.The structure of TPA was characterized by IR and NMR spectra.The conditions were investigated of extraction and separation of lanthanum and cerium mixed ions by TPA.And the extraction and separation mechanism of La^3+and Ce^4+by TPA was initially discussed.TPA has the highest extraction and separation efficiency for La^3+and Ce^4+,and the Ce^4+/La^3+separation factor is 6.74 under the optimal conditions as follows:aqueous phase pH=6.5,organic/aqueous phase ratio of 1∶1,extraction time of 150 min and extractant concentration of 3.0×10^-3 mol/L.TPA is slightly better than the traditional extractant P507-sulfonated kerosene,and there is no need to saponify the La^3+and Ce4+mixed solution,and no ammonia nitrogen wastewater to be produced.TPA has strong selectivity for Ce^4+in La3+and Ce^4+mixed solution,and high-efficiency,ammonia and nitrogen-free extraction and separation of La3+and Ce^4+is possible by multi-stage centrifugal extraction fractionation.

The process of vanadium extration from stone coal by acid leaching with NaNO2 as the leaching aid was studied.The effects of sulfuric acid dosage,sodium nitrite dosage,solid-liquid ratio,leaching temperature and leaching time on vanadium leaching rate were investigated by single factor experiments and orthogonal experiments.The results show that the leaching rate of vanadium reaches 95.0%when NaNO2 mass fraction is 1%of the mass of stone coal vanadium ore,the volume consumption of H2SO4 is 30%of the mass of stone coal vanadium ore,the liquid-solid ratio is 0.6∶1,leaching temperature is 100℃,and leaching time is 12 h.Compared with the experiment without sodium nitrite as leaching aid,vanadium leaching rate is increased by 20%.Using NaNO2 oxidative acid leaching technology to extract V not only reduces NaNO2 dosage,but also eliminates the pollution of toxic gases such as HCl and Cl2,saves energy without roasting process,and greatly improves the leaching rate of vanadium.

A large amount of silicon exists in the residue after titanium extraction from titanium-rich residue by ammonium bisulfate roasting.The effects of various parameters in the experimental process of extracting silicon from the residue after caustic alkali leaching are systematically studied.The results show that SiO2 extraction rate can reach 78.4%under the experimental conditions of reaction temperature of 220℃,mass ratio of caustic alkali to residue of 3.5∶1,liquid-solid ratio of 5.5∶1,reaction time of 50 min and stirring speed of 400 r/min.The alkali leaching kinetic analysis results show that the reaction process is controlled by internal diffusion.The apparent activation energy of the reaction is 24.047 kJ/mol,and the kinetics equation can be expressed as 1+2(1-x)-3(1-x)^2/3=2.415 exp[-24 047/(RT)]·t.

Using spherical shell shaped WC-12 Co composite powder prepared by spray conversion as raw materials,ultra-fine structured WC-12 Co coating was prepared on 45#steel substrate by high velocity oxygen-fuel(HVOF)spray.The microhardness and fracture toughness of the coating were investigated.The phases,microstructure and wear resistance of the coating were analyzed by XRD,SEM and wear testing machine.The results indicate that moderate decarbonization reaction of WC-12 Co composite powder with porous spherical shell occurs during HVOF spraying.The coating contains not only WC and W2C phases,but also a small amount of W phase.The coating is highly densified and shows rock stratum structure,with average microhardness HV0.3 and fracture toughness of 1 205.5 and 4.96 MPa·m^1/2,respectively.During wearing,the binding phase of the coating is ploughed by SiO2 to form discrete grooves,and the fine WC grains from stripping and cracking of WC grains become new abrasives,which grind coarse grains or accumulate in cracks to aggravate cracking.

TaC ceramic materials were fabricated by hot pressing sintering and the effect of sintering temperature on the microstructure and mechanical properties of the ceramics was investigated.The corrosion resistance experiment in molten cerium was carried out with coating method,and scanning electron microscopy(SEM)and X-ray diffraction(XRD)were used to characterize the properties after corrosion,in order to reveal the corrosion mechanism.The results show that with the increase of sintering temperature,both the density and mechanical properties of TaC ceramics are improved to some extent.Its density reaches 98.29%and mechanical properties achieve the best at the sintering temperature of 2 100℃.In the anti-molten cerium corrosion experiment at 1 400℃,the corrosion rate of TaC ceramic decreases with the extension of corrosion time,and its corrosion rate reduces to 0.65μm/h after corrosion for 10 h.There is no change in phase of TaC ceramics after corrosion,but the corrosion mechanism gradually changes from initial crystal boundary corrosion to grain corrosion.

The effects of superheat degree on smelting of Sm-Fe alloy were investigated by means of ICP,XRD,SEM and EDS.The results show that with the increase of superheat degree,the content of samarium in Sm-Fe alloy is significantly reduced after smelting,and the volatilization rate of samarium element increases at first and then decreases.The phase composition of Sm-Fe alloy is greatly affected by superheat degree.With the increase of superheat degree,both Sm2Fe17 phase and samarium-rich phase increase at first and then decrease.Theα-Fe phase in Sm-Fe alloy begins to appear and gradually increases with the increase of superheat degree,and its dendrites show regular arrangement,while the relative content of samarium-containing phases significantly decreases.

The metal cerium films were prepared on stainless steel substrate by vacuum vapor deposition.The morphology and phase structure of cerium films were investigated by scanning electron microscopy(SEM)and X-ray diffraction(XRD),and depth and chemical form of elements were measured by Auger electron spectroscopy(AES)and X-ray photoelectron spectroscopy(XPS).The results indicate that the surface of cerium film is compact and tightly bonded with stainless steel matrix,and its thickness is approximately 24μm.The surface of cerium film has been oxidized and the thickness of oxide film is about 340 nm,which is mainly composed of CeO2 and a small amount of Ce2O3.

Room temperature compression deformation experiments of Ti-55531 alloy after two-phase solution treatment were carried out using Gleeble3800 thermal simulation test machine and 6.3 MN forging simulator.SEM,XRD and TEM were used to characterize the deformed microstructure.The effect was studied of strain on room temperature compression deformation mechanism of Ti-55531 alloy after two-phase solution treatment.The results show that the microstructure of Ti-55531 alloy after two-phase solution treatment consists of primaryαp phase and residualβr phase,andαp phase has lower hardness thanβr phase.When the engineering strain of room temperature compression is 8%~10%,the dislocation of the alloy is mainly concentrated inα_p phase.As the strain increases,the dislocation density inα_p phase increases.When the engineering strain increases to 20%,a large number of dislocations are clustered atαp/βr phase boundary,serious dislocation accumulation and dislocation entanglement are formed inαp phase,and the number of activated slip systems inβr phase is also gradually increased.When the engineering strain increases to 30%,dislocation accumulation and dislocation entanglement also occur inβr phase.When the strain continues to increase and the engineering strain increases to 60%,the equiaxed primaryαp phase is elongated along the deformation direction,and a large number of dislocation cells appear in bothαp phase andβr phase.

The microstructure and mechanical properties of Ti-9 Al-5.4 Mo-1.9 Zr-0.3 Si titanium alloy were studied by metallographic microscope,X-ray diffractometer,transmission electron microscope and microhardness tester.The results show that there are a lot of equiaxialαstructure andβstructure resulting fromαstructural transformation in titanium alloy matrix before and after field treatment.The content of primaryαphase in the original microstructure of the titanium alloy is 41.2%.After the treatment with pulsed electric field,magnetic field and electromagnetic field,the content of primaryαphase changes to 42.1%,44.3%and 43.6%,respectively.Compared with the original microstructure,α-Ti axis ratio of the titanium alloy is significantly larger after external field treatment,and theα-Ti axis ratio obtained by pulse electromagnetic field treatment is the largest.The entanglement dislocation in the alloy matrix is not significantly reduced after magnetic field treatment.After electric field or pulse electromagnetic field treatment,the dislocation density in the alloy matrix is generally reduced,and the number of entanglement dislocations is also significantly reduced.The hardness of the samples obtained by various methods is basically consistent,and the hardness of the sample after pulse electromagnetic field treatment is relatively low.