The aim of this work is evaluate the intergranular corrosion on UNS S31803 steel, with heat treatments at 800 ℃, varying treatment times of 30 mins, 360 mins and 1,440 mins. The results confirm the formation of o pha...The aim of this work is evaluate the intergranular corrosion on UNS S31803 steel, with heat treatments at 800 ℃, varying treatment times of 30 mins, 360 mins and 1,440 mins. The results confirm the formation of o phases and secondary austenite （γ2）. For the analysis of the influence of o and γ2 phases, metallographic analysis were conducted through optical microscopy, potentiokinetic reactivation electrochemical techniques and potentiodynamic polarization in NaCI 3.5% solution. Microstructural analysis has shown a formation of γ2 and o phase in heat treatment, due to diffusion of chromium and molybdenum from δ phase to y phase, precipitating on δ/γ and δ/δ interfaces. The DL-EPR （Double loop electrochemical potentiokinetic reactivation） results have shown an increase of the DOS （degree of sensitization） for long periods of time on heat treatment. The results of potentiodynamic polarization showed a reduction of the corrosion and pitting potentials, followed by an increase of the current density when the UNS S31830 steel is heat treated during long periods of time.展开更多
The elemental composition,heat expansibility and breaking characteristics of limestone have been investigated with the use of an energy spectrum analyzer,a SEM,an optical microscope and an experimental heat swelling p...The elemental composition,heat expansibility and breaking characteristics of limestone have been investigated with the use of an energy spectrum analyzer,a SEM,an optical microscope and an experimental heat swelling power system.The results show that 1) the heat expansibility of limestone has anisotropic properties,and 2) the heat expansion rate in the direction perpendicular to stratification is eight times greater than the rate parallel to stratification.The changes in heat expansibility as a function of heating temperature is essentially coincident with that of swelling and breaking of mineral particles and the appearance of cracks,indicating that the reason for causing the heat expansion of rock are the structural changes of limestone caused by thermal stress,crystal transformation and mineral decomposition.The apparent destruction of limestone under high temperatures is largely characterized by rock stratification breaks.When the limestone is heated beyond a certain limit,the rock destroys into crazed cracks.展开更多
The desulfurater(BaAl2O4) was successfully synthesized with BaCO3 and Al(OH)3 powders as raw materials by microwave sintering method.The mass loss of raw materials and the characterization of the outcome were investig...The desulfurater(BaAl2O4) was successfully synthesized with BaCO3 and Al(OH)3 powders as raw materials by microwave sintering method.The mass loss of raw materials and the characterization of the outcome were investigated by means of TG-DSC,XRD and optical microscopy.The reaction mechanism was discussed.The experimental results show that synthesized BaAl2O4 by microwave sintering method is feasible.Compared with conventional sintering method,microwave sintering is a better way to synthesize BaAl2O4 with advantages of low temperature sintering,short time sintering and high synthesis rate.展开更多
Single-walled carbon nanotubes （SWCNTs） illuminated by white light should appear colored due to resonance Rayleigh scattering. However, true-color imaging of SWCNTs on substrates has not been reported, because of th...Single-walled carbon nanotubes （SWCNTs） illuminated by white light should appear colored due to resonance Rayleigh scattering. However, true-color imaging of SWCNTs on substrates has not been reported, because of the extremely low scattering intensity of SWCNTs and the strong substrate scattering. Here we show that Rayleigh scattering can be greatly enhanced by the interface dipole enhancement effect. Consequently colorful SWCNTs on substrates can be directly imaged under an optical microscope by wide field supercontinuum laser illumination, which facilitates high throughput chirality assignment of individual SWCNTs. This approach, termed ＂Rayleigh imaging microscopy＂, is not restricted to SWCNTs, but widely applicable to a variety of nanomaterials, which enables the colorful nanoworld to be explored under optical microscopes.展开更多
This paper expounds upon the basic principle of scanning electron microscopy(SEM),the main features of image types,and different signals,and the applications and prospects in earth sciences research are reviewed.High-...This paper expounds upon the basic principle of scanning electron microscopy(SEM),the main features of image types,and different signals,and the applications and prospects in earth sciences research are reviewed.High-resolution field emission SEM allows observation and investigation of a very fine micro area in situ.Using low-vacuum mode SEM,geological insulating samples can be analyzed directly without coating,demonstrating the wide application prospect.Combined with backscatter detector(BSE),energy dispersal X-ray spectroscopy(EDS),cathodoluminescence spectrometry(CL),and electron back-scattering diffraction(EBSD),SEM can yield multiple types of information about geological samples at the same time,such as superficial microstructure,CL analysis,BSE image,component analysis,and crystal structure features.In this paper,we use examples to discuss the geological application of SEM.We stress that we should not only focus on the CL image analysis,but strengthen CL spectrum analyses of minerals.These results will effectively reveal the mineral crystal lattice defects and trace element composition and can help to reconstruct mineral growth conditions precisely.展开更多
文摘The aim of this work is evaluate the intergranular corrosion on UNS S31803 steel, with heat treatments at 800 ℃, varying treatment times of 30 mins, 360 mins and 1,440 mins. The results confirm the formation of o phases and secondary austenite （γ2）. For the analysis of the influence of o and γ2 phases, metallographic analysis were conducted through optical microscopy, potentiokinetic reactivation electrochemical techniques and potentiodynamic polarization in NaCI 3.5% solution. Microstructural analysis has shown a formation of γ2 and o phase in heat treatment, due to diffusion of chromium and molybdenum from δ phase to y phase, precipitating on δ/γ and δ/δ interfaces. The DL-EPR （Double loop electrochemical potentiokinetic reactivation） results have shown an increase of the DOS （degree of sensitization） for long periods of time on heat treatment. The results of potentiodynamic polarization showed a reduction of the corrosion and pitting potentials, followed by an increase of the current density when the UNS S31830 steel is heat treated during long periods of time.
基金Project 50574037 supported by the National Natural Science Foundation of China
文摘The elemental composition,heat expansibility and breaking characteristics of limestone have been investigated with the use of an energy spectrum analyzer,a SEM,an optical microscope and an experimental heat swelling power system.The results show that 1) the heat expansibility of limestone has anisotropic properties,and 2) the heat expansion rate in the direction perpendicular to stratification is eight times greater than the rate parallel to stratification.The changes in heat expansibility as a function of heating temperature is essentially coincident with that of swelling and breaking of mineral particles and the appearance of cracks,indicating that the reason for causing the heat expansion of rock are the structural changes of limestone caused by thermal stress,crystal transformation and mineral decomposition.The apparent destruction of limestone under high temperatures is largely characterized by rock stratification breaks.When the limestone is heated beyond a certain limit,the rock destroys into crazed cracks.
基金Project(50264001) supported by the National Natural Science Foundation of ChinaProject(QKH-J-2008-2009) supported by Guizhou Science and Technology Department, China
文摘The desulfurater(BaAl2O4) was successfully synthesized with BaCO3 and Al(OH)3 powders as raw materials by microwave sintering method.The mass loss of raw materials and the characterization of the outcome were investigated by means of TG-DSC,XRD and optical microscopy.The reaction mechanism was discussed.The experimental results show that synthesized BaAl2O4 by microwave sintering method is feasible.Compared with conventional sintering method,microwave sintering is a better way to synthesize BaAl2O4 with advantages of low temperature sintering,short time sintering and high synthesis rate.
基金The authors would like to thank Prof. Feng Wang, Prof. Xuedong Bai, and Prof. Kaihui Liu for helpful discussions. This work was supported by the National Basic Research Program of China （No. 2012CB932301） and the National Natural Science Foundation of China （Nos. 90921012, 11321091, 51102144, 11274190, and 51102147）.
文摘Single-walled carbon nanotubes （SWCNTs） illuminated by white light should appear colored due to resonance Rayleigh scattering. However, true-color imaging of SWCNTs on substrates has not been reported, because of the extremely low scattering intensity of SWCNTs and the strong substrate scattering. Here we show that Rayleigh scattering can be greatly enhanced by the interface dipole enhancement effect. Consequently colorful SWCNTs on substrates can be directly imaged under an optical microscope by wide field supercontinuum laser illumination, which facilitates high throughput chirality assignment of individual SWCNTs. This approach, termed ＂Rayleigh imaging microscopy＂, is not restricted to SWCNTs, but widely applicable to a variety of nanomaterials, which enables the colorful nanoworld to be explored under optical microscopes.
基金supported by the National Natural Science Foundation of China(Grant No.41402031)
文摘This paper expounds upon the basic principle of scanning electron microscopy(SEM),the main features of image types,and different signals,and the applications and prospects in earth sciences research are reviewed.High-resolution field emission SEM allows observation and investigation of a very fine micro area in situ.Using low-vacuum mode SEM,geological insulating samples can be analyzed directly without coating,demonstrating the wide application prospect.Combined with backscatter detector(BSE),energy dispersal X-ray spectroscopy(EDS),cathodoluminescence spectrometry(CL),and electron back-scattering diffraction(EBSD),SEM can yield multiple types of information about geological samples at the same time,such as superficial microstructure,CL analysis,BSE image,component analysis,and crystal structure features.In this paper,we use examples to discuss the geological application of SEM.We stress that we should not only focus on the CL image analysis,but strengthen CL spectrum analyses of minerals.These results will effectively reveal the mineral crystal lattice defects and trace element composition and can help to reconstruct mineral growth conditions precisely.
