To investigate the hydrogen permeability of calcium fluoride used for electroslag remelting （ESR） process, ＂Gas-slag- metal＂ osmosis process under argon atmosphere saturated with water vapor at 318 K was used to s...To investigate the hydrogen permeability of calcium fluoride used for electroslag remelting （ESR） process, ＂Gas-slag- metal＂ osmosis process under argon atmosphere saturated with water vapor at 318 K was used to study the hydrogen permeability of slag containing calcium fluoride. The results indicate that the conventional slag, consisting of 70% CaF2 and 30% A1203, has the lowest hydrogen permeability. A parameter EH was proposed for evaluation of the hydrogen permeability of slags containing calcium fluoride. The hydrogen permeability decreases with increasing EH to a certain extent. An appropriate choice of slag for the ESR process can be obtained. These results also suggest that the hydrogen pick-up in steel after remelting might be reduced when a slag with low hydrogen permeability is used.展开更多
An attempt was made to build up a thick and compact oxide layer rapidly by pre-treating the Pb-Ag-Nd anode in fluoride-containing H2SO4 solution. The passivation reaction of Pb-Ag-Nd anode during pre-treatment process...An attempt was made to build up a thick and compact oxide layer rapidly by pre-treating the Pb-Ag-Nd anode in fluoride-containing H2SO4 solution. The passivation reaction of Pb-Ag-Nd anode during pre-treatment process was investigated using cyclic voltammetry, linear scanning voltammetry, environmental scanning electron microscopy and X-ray diffraction analysis. The results show that Pb F2 and PbSO4 are formed near the potential of Pb/PbSO4 couple. The pre-treatment in fluoride-containing H2SO4 solution contributes to the formation of a thick, compact and adherent passive film. Furthermore, pre-treatment in fluoride-containing H2SO4 solution also facilitates the formation of PbO2 on the anodic layer, and the reason could be attributed to the formation of more PbF2 and PbSO4 during the pre-treatment which tend to transform to PbO2 during the following electrowinning process. In addition, the anodic layer on anode with pre-treatment in fluoride-containing H2SO4 solution is thick and compact, and its predominant composition is β-PbO2. In summary, the pre-treatment in fluoride-containing H2SO4 solution benefits the formation of a desirable protective layer in a short time.展开更多
Sodium fluoride and high specific area silica were synthesized by using sodium hexafluorosilicate(Na2Si F6) and sodium carbonate decahydrate(Na2CO3·10H2O). The influencing factors of react temperature, contact ti...Sodium fluoride and high specific area silica were synthesized by using sodium hexafluorosilicate(Na2Si F6) and sodium carbonate decahydrate(Na2CO3·10H2O). The influencing factors of react temperature, contact time, sodium dodecyl sulfate(SDS) and molar ratio of Na2 Si F6 to Na2CO3·10H2O were investigated. The optimum process involves the reaction of 0.075 mol Na2 Si F6 and 150 m L, 0.225 mol Na2CO3·10H2O(molar ratio of 1:3) at 85 °C for 90 min, and 2.0×10-3 mol sodium dodecyl sulfate(SDS) as additive. The results show that the purities of Si O2 and Na F at extraction yields of 96.5% and 98.0% are 91.0% and 98.6%, respectively. The obtained Si O2 were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM), Fourier transform infrared ray(FTIR), differential scanning calorimetry and thermogravimetric analysis(DSC-TGA), N2 absorption/desorption(BET) and laser particle size analyzer. The result demonstrates that Si O2 particles have a high BET surface area of 103 m2/g, and a mean grain size of 985 nm.展开更多
Garlic peel,as the raw material,was modified by loading with zirconium(IV),exhibiting quite good uptaking behaviour for fluoride anion.The adsorption experiments were carried out in batch shaking vessels,and the proce...Garlic peel,as the raw material,was modified by loading with zirconium(IV),exhibiting quite good uptaking behaviour for fluoride anion.The adsorption experiments were carried out in batch shaking vessels,and the process was strongly dependent on the pH value.The adsorption fits Langmuir model well,and the maximum adsorption capacities at equilibrium pH 2 and 6 are evaluated to be 1.10 and 0.89 mol(fluoride)/kg of Zr-loaded garlic peel gel,respectively.The evaluation of effects of coexisting anions such as nitrate,sulfate and phosphate shows that nitrate and sulfate have no negative effect on the adsorption of fluoride,while phosphate has a little effect.Adsorption kinetics of fluoride is well described by pseudo-second-order rate equation,and the corresponding adsorption rate constant is calculated to be 3.25×10?3 g/(mg·min).展开更多
Surface tensions of slag addition Mg O and Si O2 based on conventional 70%CaF 2-30%Al2O3 and 60%Ca F2-20%Ca O-20%Al2O3(mass fraction) at 1300 °C, 1400 °C and 1500 °C were investigated. Influence mechani...Surface tensions of slag addition Mg O and Si O2 based on conventional 70%CaF 2-30%Al2O3 and 60%Ca F2-20%Ca O-20%Al2O3(mass fraction) at 1300 °C, 1400 °C and 1500 °C were investigated. Influence mechanism of Mg O and Si O2 on slag surface tension was also analyzed. Results indicate that surface tension decreases with the increase of Mg O content in the case of the Mg O content(mass fraction) less than 8%, however, when Mg O content(mass fraction) is from 8% to 30%, surface tension increases with the increase of Mg O content. When Si O2 content(mass fraction) is from 2% to 8%, surface tension decreases with the increase of Si O2 content. Additionally, the relationship between surface tension and optical basicity is a monotonically increasing linear function. Research findings can provide important reference for slag design and the study of slag-metal interfacial tension.展开更多
The present article bears in itself the investigation of the authors on the ways of treating high-fluoride containing groundwater by using synthetic siderite. Effects of various physico-chemical parameters such as con...The present article bears in itself the investigation of the authors on the ways of treating high-fluoride containing groundwater by using synthetic siderite. Effects of various physico-chemical parameters such as contact time,initial F^-concentration,temperature and pH of solution,absorbent dose,and coexistence anions on F^-adsorption were studied in terms of batch tests.It was found that,as contact time increased。展开更多
A constant-composition technique has been used to study thekinetic of dissolution of barium fluoride in which the activities of the latticeions were maintained constant during the experiments. The method enableskineti...A constant-composition technique has been used to study thekinetic of dissolution of barium fluoride in which the activities of the latticeions were maintained constant during the experiments. The method enableskinetic data to be obtained at very low undersaturation. A striking change inthe mechanism of dissolution is observed as the driving force is changed. Athigher driving forces (relative undersaturation 0.15--0.20) the process appearsto follow normal diffusion-controlled dissolution, while at very low undersatu-ration (0.04--0.12) a surface controlled reaction predominates. The tworegions of undersaturation a show marked difference in reactions.展开更多
The influence of grain size or grain refinement on the corrosion of Zr alloy is clarified by employing a series of electrochemical analyses and characterization techniques.The corrosion resistance,as a function of exp...The influence of grain size or grain refinement on the corrosion of Zr alloy is clarified by employing a series of electrochemical analyses and characterization techniques.The corrosion resistance,as a function of exposure time,F−concentration,and solution temperatures,of Zr alloys with different grain sizes is ascertained.The results confirm that refining the grain size can effectively enhance the short-time corrosion properties of Zr alloy in HNO_(3) with F−.The fine grained Zr alloy(~10μm in diameter)consistently exhibits a lower corrosion current density,ranging from 18%to 46%lower than that of the coarse-grained Zr alloy(~44μm).The enhanced corrosion resistance is attributed to the high density grain boundaries,which promote oxide stability,and accelerate the creation of the protective layer.The high corrosion rate and pseudo-passivation behavior of Zr alloys in fluorinated nitric acid originate from the accelerated“dissolution-passivation”of the oxide film.However,the grain refinement does not provide enduring anti-corrosion for Zr alloys.To meet the operation of spent fuel reprocessing,additional systematic efforts are required to evaluate the long term effect of grain refinement.展开更多
Boron-based fuels,recognized for their high energy density and potential in energetic applications,encounter challenges such as long ignition delays and incomplete combustion,which result in reduced combustion efficie...Boron-based fuels,recognized for their high energy density and potential in energetic applications,encounter challenges such as long ignition delays and incomplete combustion,which result in reduced combustion efficiency and limited performance in aerospace propulsion.In this study,boron carbide(B4C)is investigated as an alternative fuel to pristine boron due to its favorable gas-phase combustion.Both metal oxide(nickel oxide(NiO))and metal fluoride(nickel fluoride(NiF_(2)))are selected as oxidizing modifiers to enhance the reactivity of B4C.A method combining laser ignition with optical diagnostics is employed to investigate the enhancing effects of different oxidizers on the ignition and combustion characteristics of B4C.Both NiO and NiF_(2)can significantly increase the combustion radiation intensity and reduce the time to maximum intensity of B4C.Differential scanning calorimetry,in-situ X-ray diffraction,and Fourier transform infrared spectroscopy were used for simultaneous thermal analysis of the B4C composite powders.Combined thermal analysis showed that the effects of NiO and NiF_(2)on promoting B4C combustion is mainly achieved via the formation of NimBn and the release of a large number of gas products.It is reasonable to speculate that the phase separation at the B2O3/NimBn interface forms new pathways for oxygen diffusion and reaction with the B core.The difference in the combustion mechanism of B4C with NiO and NiF_(2)lies in the gas phase products,i.e.,CO_(2)and BF3,respectively,thus leading to significant differences in their reaction processes.展开更多
Polyvinylidene fluoride/lead zirconate titanate(PVDF/PZT)composite films have been prepared by direct ink writing and the effect of PZT content on crystallization behavior and electrical properties of film were system...Polyvinylidene fluoride/lead zirconate titanate(PVDF/PZT)composite films have been prepared by direct ink writing and the effect of PZT content on crystallization behavior and electrical properties of film were systematically investigated.The composite films were characterized by scanning electron microscope(SEM),X-ray diffractometer(XRD),Flourier transform infrared spectroscope(FTIR)and differential scanning calorimeter(DSC).The results show that,surface modified PZT powder(PZT@PDA)is successfully coated by polydopamine(PDA),resulting in a large number of polar groups that interact with the-CF_(2)-groups in PVDF,inducing the generation of polarβphase due to hydrogen bonding formed in the interaction.Theβphase content in composite film increases with increasing PZT@PDA content,up to 28.09%as with 5 wt.%PZT@PDA.PZT@PDA plays a role of nucleating agent to promote the generation of polar phases in the film and also acts as an impurity hindering the growth of nuclei to reduce crystallinity.Moreover,the presence of PZT@PDA in interfaces provides more sites for the occurrence of interfacial polarization and thus improving the electrical properties of films.The composite film with 5 wt.%PZT@PDA possesses the highest dielectric constant(8.61)and residual polarization value(0.6803μC/cm^(2)).展开更多
To recover metal from copper slags,a new process involving two steps of oxidative desulfurization followed by smelting reduction was proposed in which one hazardous waste(waste cathode carbon)was used to treat another...To recover metal from copper slags,a new process involving two steps of oxidative desulfurization followed by smelting reduction was proposed in which one hazardous waste(waste cathode carbon)was used to treat another(copper slags).The waste cathode carbon is used not only as a reducing agent but also as a fluxing agent to decrease slag melting point.Upon holding for 60 min in air atmosphere first and then smelting with 14.4 wt%waste cathode carbon and 25 wt%CaO for 180 min in high purity Ar atmosphere at 1450℃,the recovery rates of Cu and Fe reach 95.89%and 94.64%,respectively,and meanwhile greater than 90%of the fluoride from waste cathode carbon is transferred into the final slag as CaF_(2) and Ca_(2)Si_(2)F_(2)O_(7),which makes the content of soluble F in the slag meet the national emission standard.Besides,the sulphur content in the obtained Fe-Cu alloy is low to 0.03 wt%.展开更多
牛瑞燕:副教授,博士研究方向:环境兽医学近年来发表的代表性作品论文1.Effects of fluoride on microtubule ultrastructure and expression of Tubα1a and Tubβ2a in mouse hippocampus.Chemosphere 2015;139:422-427,(第一作者,SCI...牛瑞燕:副教授,博士研究方向:环境兽医学近年来发表的代表性作品论文1.Effects of fluoride on microtubule ultrastructure and expression of Tubα1a and Tubβ2a in mouse hippocampus.Chemosphere 2015;139:422-427,(第一作者,SCI收录)2.Changes in Liver antioxidant status of offspring mice induced by maternal fluoride exposure during gestation and lactation.Biol Trace Elem Res 2016;172(1):172-178.展开更多
基金Project(50904015) supported by the National Natural Science Foundation of ChinaProject(N090402012) supported by the Fundamental Research Funds for Central Universities of China
文摘To investigate the hydrogen permeability of calcium fluoride used for electroslag remelting （ESR） process, ＂Gas-slag- metal＂ osmosis process under argon atmosphere saturated with water vapor at 318 K was used to study the hydrogen permeability of slag containing calcium fluoride. The results indicate that the conventional slag, consisting of 70% CaF2 and 30% A1203, has the lowest hydrogen permeability. A parameter EH was proposed for evaluation of the hydrogen permeability of slags containing calcium fluoride. The hydrogen permeability decreases with increasing EH to a certain extent. An appropriate choice of slag for the ESR process can be obtained. These results also suggest that the hydrogen pick-up in steel after remelting might be reduced when a slag with low hydrogen permeability is used.
基金Projects(51204208,51374240)supported by the National Natural Science Foundation of ChinaProject(2014zzts028)supported by the Fundamental Research Funds for the Central Universities of Central South University,China
文摘An attempt was made to build up a thick and compact oxide layer rapidly by pre-treating the Pb-Ag-Nd anode in fluoride-containing H2SO4 solution. The passivation reaction of Pb-Ag-Nd anode during pre-treatment process was investigated using cyclic voltammetry, linear scanning voltammetry, environmental scanning electron microscopy and X-ray diffraction analysis. The results show that Pb F2 and PbSO4 are formed near the potential of Pb/PbSO4 couple. The pre-treatment in fluoride-containing H2SO4 solution contributes to the formation of a thick, compact and adherent passive film. Furthermore, pre-treatment in fluoride-containing H2SO4 solution also facilitates the formation of PbO2 on the anodic layer, and the reason could be attributed to the formation of more PbF2 and PbSO4 during the pre-treatment which tend to transform to PbO2 during the following electrowinning process. In addition, the anodic layer on anode with pre-treatment in fluoride-containing H2SO4 solution is thick and compact, and its predominant composition is β-PbO2. In summary, the pre-treatment in fluoride-containing H2SO4 solution benefits the formation of a desirable protective layer in a short time.
文摘Sodium fluoride and high specific area silica were synthesized by using sodium hexafluorosilicate(Na2Si F6) and sodium carbonate decahydrate(Na2CO3·10H2O). The influencing factors of react temperature, contact time, sodium dodecyl sulfate(SDS) and molar ratio of Na2 Si F6 to Na2CO3·10H2O were investigated. The optimum process involves the reaction of 0.075 mol Na2 Si F6 and 150 m L, 0.225 mol Na2CO3·10H2O(molar ratio of 1:3) at 85 °C for 90 min, and 2.0×10-3 mol sodium dodecyl sulfate(SDS) as additive. The results show that the purities of Si O2 and Na F at extraction yields of 96.5% and 98.0% are 91.0% and 98.6%, respectively. The obtained Si O2 were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM), Fourier transform infrared ray(FTIR), differential scanning calorimetry and thermogravimetric analysis(DSC-TGA), N2 absorption/desorption(BET) and laser particle size analyzer. The result demonstrates that Si O2 particles have a high BET surface area of 103 m2/g, and a mean grain size of 985 nm.
基金Project(11140065) supported by Research Program for Returned Oversea Scholars of China
文摘Garlic peel,as the raw material,was modified by loading with zirconium(IV),exhibiting quite good uptaking behaviour for fluoride anion.The adsorption experiments were carried out in batch shaking vessels,and the process was strongly dependent on the pH value.The adsorption fits Langmuir model well,and the maximum adsorption capacities at equilibrium pH 2 and 6 are evaluated to be 1.10 and 0.89 mol(fluoride)/kg of Zr-loaded garlic peel gel,respectively.The evaluation of effects of coexisting anions such as nitrate,sulfate and phosphate shows that nitrate and sulfate have no negative effect on the adsorption of fluoride,while phosphate has a little effect.Adsorption kinetics of fluoride is well described by pseudo-second-order rate equation,and the corresponding adsorption rate constant is calculated to be 3.25×10?3 g/(mg·min).
基金Project(51274266)supported by the National Natural Science Foundation of ChinaProject(N120502002)supported by the Fundamental Research Funds for Central Universities of ChinaProject(LR2013009)supported by the Program for Liaoning Excellent Talents in University,China
文摘Surface tensions of slag addition Mg O and Si O2 based on conventional 70%CaF 2-30%Al2O3 and 60%Ca F2-20%Ca O-20%Al2O3(mass fraction) at 1300 °C, 1400 °C and 1500 °C were investigated. Influence mechanism of Mg O and Si O2 on slag surface tension was also analyzed. Results indicate that surface tension decreases with the increase of Mg O content in the case of the Mg O content(mass fraction) less than 8%, however, when Mg O content(mass fraction) is from 8% to 30%, surface tension increases with the increase of Mg O content. When Si O2 content(mass fraction) is from 2% to 8%, surface tension decreases with the increase of Si O2 content. Additionally, the relationship between surface tension and optical basicity is a monotonically increasing linear function. Research findings can provide important reference for slag design and the study of slag-metal interfacial tension.
文摘The present article bears in itself the investigation of the authors on the ways of treating high-fluoride containing groundwater by using synthetic siderite. Effects of various physico-chemical parameters such as contact time,initial F^-concentration,temperature and pH of solution,absorbent dose,and coexistence anions on F^-adsorption were studied in terms of batch tests.It was found that,as contact time increased。
文摘A constant-composition technique has been used to study thekinetic of dissolution of barium fluoride in which the activities of the latticeions were maintained constant during the experiments. The method enableskinetic data to be obtained at very low undersaturation. A striking change inthe mechanism of dissolution is observed as the driving force is changed. Athigher driving forces (relative undersaturation 0.15--0.20) the process appearsto follow normal diffusion-controlled dissolution, while at very low undersatu-ration (0.04--0.12) a surface controlled reaction predominates. The tworegions of undersaturation a show marked difference in reactions.
基金Project(U2067217)supported by the National Natural Science Foundation of ChinaProject(SASTIND)supported by the State Administration of Science,Technology and Industry for National Defense,ChinaProject(2020M683572)supported by China Postdoctoral Science Foundation。
文摘The influence of grain size or grain refinement on the corrosion of Zr alloy is clarified by employing a series of electrochemical analyses and characterization techniques.The corrosion resistance,as a function of exposure time,F−concentration,and solution temperatures,of Zr alloys with different grain sizes is ascertained.The results confirm that refining the grain size can effectively enhance the short-time corrosion properties of Zr alloy in HNO_(3) with F−.The fine grained Zr alloy(~10μm in diameter)consistently exhibits a lower corrosion current density,ranging from 18%to 46%lower than that of the coarse-grained Zr alloy(~44μm).The enhanced corrosion resistance is attributed to the high density grain boundaries,which promote oxide stability,and accelerate the creation of the protective layer.The high corrosion rate and pseudo-passivation behavior of Zr alloys in fluorinated nitric acid originate from the accelerated“dissolution-passivation”of the oxide film.However,the grain refinement does not provide enduring anti-corrosion for Zr alloys.To meet the operation of spent fuel reprocessing,additional systematic efforts are required to evaluate the long term effect of grain refinement.
基金The National Natural Science Foundation of China(Grant Nos.523B2063 and 52376089)。
文摘Boron-based fuels,recognized for their high energy density and potential in energetic applications,encounter challenges such as long ignition delays and incomplete combustion,which result in reduced combustion efficiency and limited performance in aerospace propulsion.In this study,boron carbide(B4C)is investigated as an alternative fuel to pristine boron due to its favorable gas-phase combustion.Both metal oxide(nickel oxide(NiO))and metal fluoride(nickel fluoride(NiF_(2)))are selected as oxidizing modifiers to enhance the reactivity of B4C.A method combining laser ignition with optical diagnostics is employed to investigate the enhancing effects of different oxidizers on the ignition and combustion characteristics of B4C.Both NiO and NiF_(2)can significantly increase the combustion radiation intensity and reduce the time to maximum intensity of B4C.Differential scanning calorimetry,in-situ X-ray diffraction,and Fourier transform infrared spectroscopy were used for simultaneous thermal analysis of the B4C composite powders.Combined thermal analysis showed that the effects of NiO and NiF_(2)on promoting B4C combustion is mainly achieved via the formation of NimBn and the release of a large number of gas products.It is reasonable to speculate that the phase separation at the B2O3/NimBn interface forms new pathways for oxygen diffusion and reaction with the B core.The difference in the combustion mechanism of B4C with NiO and NiF_(2)lies in the gas phase products,i.e.,CO_(2)and BF3,respectively,thus leading to significant differences in their reaction processes.
基金Project(22020JJ4729)supported by the Natural Science Foundation of Hunan Province,China。
文摘Polyvinylidene fluoride/lead zirconate titanate(PVDF/PZT)composite films have been prepared by direct ink writing and the effect of PZT content on crystallization behavior and electrical properties of film were systematically investigated.The composite films were characterized by scanning electron microscope(SEM),X-ray diffractometer(XRD),Flourier transform infrared spectroscope(FTIR)and differential scanning calorimeter(DSC).The results show that,surface modified PZT powder(PZT@PDA)is successfully coated by polydopamine(PDA),resulting in a large number of polar groups that interact with the-CF_(2)-groups in PVDF,inducing the generation of polarβphase due to hydrogen bonding formed in the interaction.Theβphase content in composite film increases with increasing PZT@PDA content,up to 28.09%as with 5 wt.%PZT@PDA.PZT@PDA plays a role of nucleating agent to promote the generation of polar phases in the film and also acts as an impurity hindering the growth of nuclei to reduce crystallinity.Moreover,the presence of PZT@PDA in interfaces provides more sites for the occurrence of interfacial polarization and thus improving the electrical properties of films.The composite film with 5 wt.%PZT@PDA possesses the highest dielectric constant(8.61)and residual polarization value(0.6803μC/cm^(2)).
基金Project(U1602272)supported by the National Natural Science Foundation of China。
文摘To recover metal from copper slags,a new process involving two steps of oxidative desulfurization followed by smelting reduction was proposed in which one hazardous waste(waste cathode carbon)was used to treat another(copper slags).The waste cathode carbon is used not only as a reducing agent but also as a fluxing agent to decrease slag melting point.Upon holding for 60 min in air atmosphere first and then smelting with 14.4 wt%waste cathode carbon and 25 wt%CaO for 180 min in high purity Ar atmosphere at 1450℃,the recovery rates of Cu and Fe reach 95.89%and 94.64%,respectively,and meanwhile greater than 90%of the fluoride from waste cathode carbon is transferred into the final slag as CaF_(2) and Ca_(2)Si_(2)F_(2)O_(7),which makes the content of soluble F in the slag meet the national emission standard.Besides,the sulphur content in the obtained Fe-Cu alloy is low to 0.03 wt%.
文摘牛瑞燕:副教授,博士研究方向:环境兽医学近年来发表的代表性作品论文1.Effects of fluoride on microtubule ultrastructure and expression of Tubα1a and Tubβ2a in mouse hippocampus.Chemosphere 2015;139:422-427,(第一作者,SCI收录)2.Changes in Liver antioxidant status of offspring mice induced by maternal fluoride exposure during gestation and lactation.Biol Trace Elem Res 2016;172(1):172-178.
