The oxidizing roasting process of carbon ferrochrome to prepare potassium chromate in the presence of potassium carbonate and air was investigated. The effects of reaction temperature, reaction time, mole ratio of pot...The oxidizing roasting process of carbon ferrochrome to prepare potassium chromate in the presence of potassium carbonate and air was investigated. The effects of reaction temperature, reaction time, mole ratio of potassium carbonate to carbon ferrochrome were studied, and thermodynamics and kinetics were also discussed. It was observed that the reaction temperature and reaction time had a significant influence on the roasting reaction of carbon ferrochrome. The reaction mechanism changed greatly as the temperature varied. A two-stage roasting process was favorable for the roasting reaction, and a chromium recovery rate of 97.06% was obtained through this two-stage roasting method. The chromium residue yielded from this method was only 1/3 of the product. Moreover, the component of Fe in the residue was as high as 55.04%. Therefore, it can be easily recovered to produce sponge iron, realizing complete detoxication and zero-emission of chromium residue.展开更多
A kind of environmental friendly anodizing routine for AZ91D magnesium alloy,based on an alkaline borate-potassium acid phthalate（KAP） electrolyte,was studied.The effect of KAP on the properties of the anodized film...A kind of environmental friendly anodizing routine for AZ91D magnesium alloy,based on an alkaline borate-potassium acid phthalate（KAP） electrolyte,was studied.The effect of KAP on the properties of the anodized film was investigated by scanning electron microscopy（SEM）,X-ray diffraction（XRD）,energy dispersive spectrometry（EDS）,potentiodynamic polarization and electrochemical impedance spectroscopy（EIS）,respectively.The results showed that the anodizing process,surface morphology,thickness,phase structure and corrosion resistance of the anodized film were strongly dependent on the concentration of KAP.In the presence of adequate KAP,a compact and smooth anodized film with excellent corrosion resistance was obtained.展开更多
Ultrafine diamond (UFD) is produced at high pressure and high temperature generated by explosive detonation. We manage to search for a new technology to purify the UFD by using potassium permanganate and concentrated ...Ultrafine diamond (UFD) is produced at high pressure and high temperature generated by explosive detonation. We manage to search for a new technology to purify the UFD by using potassium permanganate and concentrated sulfuric acid as oxidant. The experiment results show that, compared with others, the purifying effect by this technology is satisfactory and is a more efficient, cheaper, and safer purification technology with less pollution and less investment. It can be put into commercial use. The related principle of the technology is discussed. It is believed that the atomic state oxygen produced during the reaction mechanism is an active substances which would react with the graphite——the main impurity existing in the detonation soot, and the reaction temperature is the key factor in the process.展开更多
The crystal and molecular structure of the title compound K(C14 H20O5)2AuCl4 has been determined by X-ray diffraction method.The crystallographic data are as follows;Mr=914.51,triclinic,space group P1,a=10.988(2),b=13...The crystal and molecular structure of the title compound K(C14 H20O5)2AuCl4 has been determined by X-ray diffraction method.The crystallographic data are as follows;Mr=914.51,triclinic,space group P1,a=10.988(2),b=13.472(4),c=13.696(2)A,α=77.72(1),β=79.02(2),γ=64.92(2)°,V=1782.6(4)A3,Z=2,Dc=1.704 g.cm-3,μ=45.858 cm-1,F(000)=454,R=0.019,Rw=0.018 for 5697 observed reflections with I≥3σ(I).X-ray structure determination shows that benzo-15-crown-5(B15C5)forms a 2:1 complex with KAu-C14 in which K+is sandwiched between two crown rings.The dihedral angle between these two ether oxygen planes is 11.9°.The anion AuCl4-has a planar square configuration which is bound with the complex cation K(B15C5)2+by electrostatic force to form an ion-pair.展开更多
Two different types of potential oscillations have been identified for the first time during dichromate reduction on a gold electrode in a solution of dilute sulfuric acid. One occurs before hydrogen evolution due to ...Two different types of potential oscillations have been identified for the first time during dichromate reduction on a gold electrode in a solution of dilute sulfuric acid. One occurs before hydrogen evolution due to the formation and dissolution of passivating films of low-valence chromium oxides, and the other generates, accompanying periodic hydrogen evolution, from the coupling of electrochemical reactions with diffusive and convective mass transport. More interestingly, these two types of oscillations correspond to two crossing loops in the cyclic voltammogram （CV）. Such a relation of oscillations with crossed CVs will provide a new way to find electrochemical oscillatory systems systematically and rapidly.展开更多
This paper presents the results of molecular dynamics (MD) simulation on the rutile titanium dioxide and potassium hexatitanate (K2O.6TiO2 or K2Ti6O13) crystal. The interaction of atoms is described by two-body centra...This paper presents the results of molecular dynamics (MD) simulation on the rutile titanium dioxide and potassium hexatitanate (K2O.6TiO2 or K2Ti6O13) crystal. The interaction of atoms is described by two-body central force interatomic potential, which includes Coulombic term, Gilbert-type repulsion term, van der Waals term and Morse-type potential. The optimized crystal structure of rutile TiO2 is in very good agreement with the experimental data in the literature. The present MD simulation also gives several physical properties, including volume thermal expansivity and elastic bulk modulus.展开更多
Microarc oxidation （MAO） coatings were prepared on 2024 aluminum alloy in a Na2SiO3-KOH electrolyte with KNinO4 addition varying from 0 to 4 g/L. The microstructure and phases of the coatings were characterized by s...Microarc oxidation （MAO） coatings were prepared on 2024 aluminum alloy in a Na2SiO3-KOH electrolyte with KNinO4 addition varying from 0 to 4 g/L. The microstructure and phases of the coatings were characterized by scanning electron microscopy （SEM） and X-ray diffractometry （XRD）, respectively. The corrosion resistance of MAO coatings was evaluated by electrochemical potentiodynamic polarization in 5% （mass fraction） NaCl solution. The results show that when KMnO4 is added into base electrolyte, the growth speed of oxide coatings is increased obviously. The main phase of oxide coatings is Al2O3, and the contents of MnO2 and MnEA104 phases are increased at the top of oxide coatings with increasing the concentration of KMnO4. The solute elements participate in forming the oxide coatings. When a proper concentration of KMnO4 （2.5 g/L） is added into the base solution, the micropores of the MAO coatings are small and compact, and the corrosion resistance of oxide coatings is increased largely.展开更多
基金Project(2009GK2003)supported by the Natural Science Foundation of Hunan Province,China
文摘The oxidizing roasting process of carbon ferrochrome to prepare potassium chromate in the presence of potassium carbonate and air was investigated. The effects of reaction temperature, reaction time, mole ratio of potassium carbonate to carbon ferrochrome were studied, and thermodynamics and kinetics were also discussed. It was observed that the reaction temperature and reaction time had a significant influence on the roasting reaction of carbon ferrochrome. The reaction mechanism changed greatly as the temperature varied. A two-stage roasting process was favorable for the roasting reaction, and a chromium recovery rate of 97.06% was obtained through this two-stage roasting method. The chromium residue yielded from this method was only 1/3 of the product. Moreover, the component of Fe in the residue was as high as 55.04%. Therefore, it can be easily recovered to produce sponge iron, realizing complete detoxication and zero-emission of chromium residue.
基金Projects (50771092,21073162) supported by the National Natural Science Foundation of ChinaProject (08JC1421600) supported by the Science and Technology Commission of Shanghai,ChinaProject (2008AZ2018) supported by the Science and Technology Bureau of Jiaxing,China
文摘A kind of environmental friendly anodizing routine for AZ91D magnesium alloy,based on an alkaline borate-potassium acid phthalate（KAP） electrolyte,was studied.The effect of KAP on the properties of the anodized film was investigated by scanning electron microscopy（SEM）,X-ray diffraction（XRD）,energy dispersive spectrometry（EDS）,potentiodynamic polarization and electrochemical impedance spectroscopy（EIS）,respectively.The results showed that the anodizing process,surface morphology,thickness,phase structure and corrosion resistance of the anodized film were strongly dependent on the concentration of KAP.In the presence of adequate KAP,a compact and smooth anodized film with excellent corrosion resistance was obtained.
文摘Ultrafine diamond (UFD) is produced at high pressure and high temperature generated by explosive detonation. We manage to search for a new technology to purify the UFD by using potassium permanganate and concentrated sulfuric acid as oxidant. The experiment results show that, compared with others, the purifying effect by this technology is satisfactory and is a more efficient, cheaper, and safer purification technology with less pollution and less investment. It can be put into commercial use. The related principle of the technology is discussed. It is believed that the atomic state oxygen produced during the reaction mechanism is an active substances which would react with the graphite——the main impurity existing in the detonation soot, and the reaction temperature is the key factor in the process.
文摘The crystal and molecular structure of the title compound K(C14 H20O5)2AuCl4 has been determined by X-ray diffraction method.The crystallographic data are as follows;Mr=914.51,triclinic,space group P1,a=10.988(2),b=13.472(4),c=13.696(2)A,α=77.72(1),β=79.02(2),γ=64.92(2)°,V=1782.6(4)A3,Z=2,Dc=1.704 g.cm-3,μ=45.858 cm-1,F(000)=454,R=0.019,Rw=0.018 for 5697 observed reflections with I≥3σ(I).X-ray structure determination shows that benzo-15-crown-5(B15C5)forms a 2:1 complex with KAu-C14 in which K+is sandwiched between two crown rings.The dihedral angle between these two ether oxygen planes is 11.9°.The anion AuCl4-has a planar square configuration which is bound with the complex cation K(B15C5)2+by electrostatic force to form an ion-pair.
文摘Two different types of potential oscillations have been identified for the first time during dichromate reduction on a gold electrode in a solution of dilute sulfuric acid. One occurs before hydrogen evolution due to the formation and dissolution of passivating films of low-valence chromium oxides, and the other generates, accompanying periodic hydrogen evolution, from the coupling of electrochemical reactions with diffusive and convective mass transport. More interestingly, these two types of oscillations correspond to two crossing loops in the cyclic voltammogram （CV）. Such a relation of oscillations with crossed CVs will provide a new way to find electrochemical oscillatory systems systematically and rapidly.
基金Supported by the Natural Science Foundation of Jiangsu Province(BK97124)the Outstanding Youth Fund of National Natural Science Foundation of China(No.29925616)and the National Natural Science Foundation of China(No.20246002 and No.20236010).
文摘This paper presents the results of molecular dynamics (MD) simulation on the rutile titanium dioxide and potassium hexatitanate (K2O.6TiO2 or K2Ti6O13) crystal. The interaction of atoms is described by two-body central force interatomic potential, which includes Coulombic term, Gilbert-type repulsion term, van der Waals term and Morse-type potential. The optimized crystal structure of rutile TiO2 is in very good agreement with the experimental data in the literature. The present MD simulation also gives several physical properties, including volume thermal expansivity and elastic bulk modulus.
基金Project(2008BAE63B00) supported by the National Key Technologies Research and Development Program of China
文摘Microarc oxidation （MAO） coatings were prepared on 2024 aluminum alloy in a Na2SiO3-KOH electrolyte with KNinO4 addition varying from 0 to 4 g/L. The microstructure and phases of the coatings were characterized by scanning electron microscopy （SEM） and X-ray diffractometry （XRD）, respectively. The corrosion resistance of MAO coatings was evaluated by electrochemical potentiodynamic polarization in 5% （mass fraction） NaCl solution. The results show that when KMnO4 is added into base electrolyte, the growth speed of oxide coatings is increased obviously. The main phase of oxide coatings is Al2O3, and the contents of MnO2 and MnEA104 phases are increased at the top of oxide coatings with increasing the concentration of KMnO4. The solute elements participate in forming the oxide coatings. When a proper concentration of KMnO4 （2.5 g/L） is added into the base solution, the micropores of the MAO coatings are small and compact, and the corrosion resistance of oxide coatings is increased largely.
