Effect of solution concentration on the structures and corrosion inhibition behavior of γ-APS films fabricated on surface of low carbon steel was systematically studied by EIS, RA-IR, and AFM. The experimental result...Effect of solution concentration on the structures and corrosion inhibition behavior of γ-APS films fabricated on surface of low carbon steel was systematically studied by EIS, RA-IR, and AFM. The experimental results indicated that the impedance of γ-APS silane treated substrates and the cross-linking degree of γ-APS films gradually increased with the increasing solution concentration. There was some noticeable transformation in molecular orientation and protective performance of γ-APS films when solution concentration was above 10vol%. High cross-linking degree and changes in molecular orientation generated γ-APS films with excellent protective performance and ordered arrangement.展开更多
The effects of Y2O3 adding methods (i.e.,co-precipitated and mixed) on the microstructure and properties of alumina-strengthened ytrria-stabilized tetragonal zirconia polycrystal (ASZ) were investigated. CYASZ and...The effects of Y2O3 adding methods (i.e.,co-precipitated and mixed) on the microstructure and properties of alumina-strengthened ytrria-stabilized tetragonal zirconia polycrystal (ASZ) were investigated. CYASZ and MYASZ were made by different adding method of Y2O3,co-precipitated and mixed,respectively. The results show that CYASZ is of uniform microstructure with fine grain size,however,MYASZ is of inhomogeneous microstructure due to the inhomogeneous distribution of ytrria. Comparing with CYASZ,the density and the strength of MYASZ are decreased,but the toughness is changed only a little. Under sliding wear test,the wear resistance of CYASZ is better than that of MYASZ.展开更多
The effect of relative humidity on the corrosion-resisting property of fluorocarbon coating was investigated by water vapor transmission technique and electrochemical impedance spectroscopy technique. Measurements wer...The effect of relative humidity on the corrosion-resisting property of fluorocarbon coating was investigated by water vapor transmission technique and electrochemical impedance spectroscopy technique. Measurements were carried out on samples, which were tested in an accelerated corrosion environment for the same time (300, 500, 800 and 1000 h). The experimental results were obtained as follows: (i) The water absorption, coating resistance and corrosion rate of metal under the coating changed with relative humidity and aging time, the results obtained by EIS are good consistent with those by water vapor transmission technique; (ii) when the subject investigated presented two time constant, the goodness of fit by EEC R(C(R(CR))) was inferior to that by EEC R(C(R(QR))), but the error of parameters acquired from the former was smaller, by which we could analyze the experiment result quantitatively. With the appearance of diffusion layer on the metal, the difference of metal capacitance was aggravated, the error of parameters acquired from EEC R(C(R(C(RW))))was bigger than that from EEC R(C(R(Q(RW)))).展开更多
The aim of this work was to study the degradation behavior of Ti-6Al-4V alloys for dental applications in acidic artificial saliva with fluoride ion using electrochemical techniques, optical microscopy, scanning elect...The aim of this work was to study the degradation behavior of Ti-6Al-4V alloys for dental applications in acidic artificial saliva with fluoride ion using electrochemical techniques, optical microscopy, scanning electron microscopy(SEM), and energy dispersive spectrometry(EDS). The experimental results showed that fluoride ion had significant influence on the degradation of Ti-6Al-4V alloys, and there was an obvious critical concentration of fluoride ion(about 0.1wt%). With increasing fluoride ion concentration, the corrosion potential(Ecorr) of alloys moved toward negative and the impedance of alloys decreased, meanwhile, noticeable transformation from minimum corrosion to severe pitting corrosion was observed on alloys surface following the dissolution of TiO_2 passive films, leading to the decrease of the corrosion resistance of alloys. The electrochemical dissolution of TiO_2 passive films involved a nucleophilic attack of fluoride atom to the titanium atom of TiO_2. In addition, Ca^(2+)and Na^+ in acidic saliva may involve the surface reactions and make the reactions more complex.展开更多
The crystal structure of silicate oxyapatite Ca2Y8Si6O26 was indexed as hexagonal,space group P63/m,a=0.93515 nm,c=0.67872 nm,α=β=90°,γ=120°,V=0.5138692 nm3.Three strong peaks located at 32.079o,32.595o,a...The crystal structure of silicate oxyapatite Ca2Y8Si6O26 was indexed as hexagonal,space group P63/m,a=0.93515 nm,c=0.67872 nm,α=β=90°,γ=120°,V=0.5138692 nm3.Three strong peaks located at 32.079o,32.595o,and 50.104o with d=2.7903,2.74649,1.8194 was in accordance with,(112),and(213) planes.The optimum concentration of Tb3+ in Ca2Y8Si6O26 to yield highest photoluminescence intensity was 10 mol.% of Y3+.The corresponding excitation spectrum consisted of an intense broad band from 220 to 260 nm.The photoluminescence measurements showed that the green emission originated from 5D4-7F5 was predominant in the measured range with strong doublet lines at 543 and 549 nm.展开更多
Cubic and monoclinic Gd2O3:Eu3+ phosphors in the range of nano-scale and submicron-scale were prepared by a modified solution combustion method.Coexistence of cubic and monoclinic phases was found in the highest lumin...Cubic and monoclinic Gd2O3:Eu3+ phosphors in the range of nano-scale and submicron-scale were prepared by a modified solution combustion method.Coexistence of cubic and monoclinic phases was found in the highest luminescent sample synthesized at 600 oC.In relation to commercial sample,the relative luminescence intensity was 49.8%.The shape of emission spectrum of the sample thus changed and the charge-transfer-state band of excitation spectrum slightly shift toward higher energies.With increasing the annealing temperature,phase transformation and correlative optical properties of Gd2O3:Eu3+ phosphors were studied.It was found that the samples were dominated by cubic structure and monoclinic structure at temperatures below and above 900 oC.展开更多
基金Funded by the National Natural Science Foundation of China(No.50801057)the Special Fund for Basic Scientific Research of Central Colleges,China University of Geosciences(Wuhan)(No.007-G1323521109)
文摘Effect of solution concentration on the structures and corrosion inhibition behavior of γ-APS films fabricated on surface of low carbon steel was systematically studied by EIS, RA-IR, and AFM. The experimental results indicated that the impedance of γ-APS silane treated substrates and the cross-linking degree of γ-APS films gradually increased with the increasing solution concentration. There was some noticeable transformation in molecular orientation and protective performance of γ-APS films when solution concentration was above 10vol%. High cross-linking degree and changes in molecular orientation generated γ-APS films with excellent protective performance and ordered arrangement.
文摘The effects of Y2O3 adding methods (i.e.,co-precipitated and mixed) on the microstructure and properties of alumina-strengthened ytrria-stabilized tetragonal zirconia polycrystal (ASZ) were investigated. CYASZ and MYASZ were made by different adding method of Y2O3,co-precipitated and mixed,respectively. The results show that CYASZ is of uniform microstructure with fine grain size,however,MYASZ is of inhomogeneous microstructure due to the inhomogeneous distribution of ytrria. Comparing with CYASZ,the density and the strength of MYASZ are decreased,but the toughness is changed only a little. Under sliding wear test,the wear resistance of CYASZ is better than that of MYASZ.
文摘The effect of relative humidity on the corrosion-resisting property of fluorocarbon coating was investigated by water vapor transmission technique and electrochemical impedance spectroscopy technique. Measurements were carried out on samples, which were tested in an accelerated corrosion environment for the same time (300, 500, 800 and 1000 h). The experimental results were obtained as follows: (i) The water absorption, coating resistance and corrosion rate of metal under the coating changed with relative humidity and aging time, the results obtained by EIS are good consistent with those by water vapor transmission technique; (ii) when the subject investigated presented two time constant, the goodness of fit by EEC R(C(R(CR))) was inferior to that by EEC R(C(R(QR))), but the error of parameters acquired from the former was smaller, by which we could analyze the experiment result quantitatively. With the appearance of diffusion layer on the metal, the difference of metal capacitance was aggravated, the error of parameters acquired from EEC R(C(R(C(RW))))was bigger than that from EEC R(C(R(Q(RW)))).
基金Funded by the National Natural Science Foundation of China(No.50801057)the National Basic Research Priorities Program of China(No.2005DKA10400-CT-1-08-06)+1 种基金the Special Fund for Basic Scientific Research of Central Colleges,China University of Geosciences(Wuhan)(No.007-G1323521109)the National Natural Science Fundation of China(81641035 and 81401524)
文摘The aim of this work was to study the degradation behavior of Ti-6Al-4V alloys for dental applications in acidic artificial saliva with fluoride ion using electrochemical techniques, optical microscopy, scanning electron microscopy(SEM), and energy dispersive spectrometry(EDS). The experimental results showed that fluoride ion had significant influence on the degradation of Ti-6Al-4V alloys, and there was an obvious critical concentration of fluoride ion(about 0.1wt%). With increasing fluoride ion concentration, the corrosion potential(Ecorr) of alloys moved toward negative and the impedance of alloys decreased, meanwhile, noticeable transformation from minimum corrosion to severe pitting corrosion was observed on alloys surface following the dissolution of TiO_2 passive films, leading to the decrease of the corrosion resistance of alloys. The electrochemical dissolution of TiO_2 passive films involved a nucleophilic attack of fluoride atom to the titanium atom of TiO_2. In addition, Ca^(2+)and Na^+ in acidic saliva may involve the surface reactions and make the reactions more complex.
基金Project supported by the Natural Science Foundation of Jiangxi Province (2009GQC0042)Foundation of Jiangxi Educational Committee (GJJ10153)+1 种基金Foundation of Jiangxi University of Science and Technology (Jxxjzd10007)Key Scientific and Technological Project of Henan Province (082102210049)
文摘The crystal structure of silicate oxyapatite Ca2Y8Si6O26 was indexed as hexagonal,space group P63/m,a=0.93515 nm,c=0.67872 nm,α=β=90°,γ=120°,V=0.5138692 nm3.Three strong peaks located at 32.079o,32.595o,and 50.104o with d=2.7903,2.74649,1.8194 was in accordance with,(112),and(213) planes.The optimum concentration of Tb3+ in Ca2Y8Si6O26 to yield highest photoluminescence intensity was 10 mol.% of Y3+.The corresponding excitation spectrum consisted of an intense broad band from 220 to 260 nm.The photoluminescence measurements showed that the green emission originated from 5D4-7F5 was predominant in the measured range with strong doublet lines at 543 and 549 nm.
基金supported by the Ministry of Science and Technology of China (2006CB601104)the Foundation of International Joint Research of Beijing (2007N08)+1 种基金Natural Science Foundation of Jiangxi Province (2009GQC0042)Foundation of Jiangxi Educational Committee (GJJ10153)
文摘Cubic and monoclinic Gd2O3:Eu3+ phosphors in the range of nano-scale and submicron-scale were prepared by a modified solution combustion method.Coexistence of cubic and monoclinic phases was found in the highest luminescent sample synthesized at 600 oC.In relation to commercial sample,the relative luminescence intensity was 49.8%.The shape of emission spectrum of the sample thus changed and the charge-transfer-state band of excitation spectrum slightly shift toward higher energies.With increasing the annealing temperature,phase transformation and correlative optical properties of Gd2O3:Eu3+ phosphors were studied.It was found that the samples were dominated by cubic structure and monoclinic structure at temperatures below and above 900 oC.