The microstructure of the RE silicide alloy was studied by SEM. The feature of the phase and the distribution of Ca, P, Al were analyzed, especially the distribution of micro-cracks and its composition were determined...The microstructure of the RE silicide alloy was studied by SEM. The feature of the phase and the distribution of Ca, P, Al were analyzed, especially the distribution of micro-cracks and its composition were determined. The result demonstrates that only a few phosphides contribute to the spontaneous crumbling of the RE silicide alloy by reacting with water and forming oxide or phosphorus oxide. The phosphorus content is not the critical factor of disintegration in the alloy studied.展开更多
The reduction mechanism of Ir in the NaCl-KCl-IrCl3 molten salt was investigated by cyclic voltammetry and chronopotentiometry, and Ir film was deposited effectively on platinum in potentiostatic mode. The morphology ...The reduction mechanism of Ir in the NaCl-KCl-IrCl3 molten salt was investigated by cyclic voltammetry and chronopotentiometry, and Ir film was deposited effectively on platinum in potentiostatic mode. The morphology and constitution of Ir film were examined by scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS） and X-ray diffraction （XRD）. It is found that the reduction mechanism of Ir（III） is a three-electron step and electro reaction is a reversible diffusion controlled process; the diffusion coefficients of Ir（III） at 1083, 1113, 1143 and 1183 K are 1.56×10-4, 2.23×10-4, 2.77×10-4 and 4.40×10-4 cm2/s, respectively, while the activation energy of the electrode reaction is 102.95 kJ/mol. The compacted Ir film reveals that the applied potential greatly affects the deposition of Ir, the thickness of Ir film deposited at the potential of reduction peak is the highest, the temperature of the molten salt also exerts an influence on deposition, the film formed at a lower temperature is thinner, but more micropores would occur on film when the temperature went too high.展开更多
In order to develop new basic light-weight refractory raw materials,natural forsterite(<0.045 mm)and magnesite(<0.045 mm)were batched according to the chemical composition of forsterite(2MgO·SiO_(2)),wet mi...In order to develop new basic light-weight refractory raw materials,natural forsterite(<0.045 mm)and magnesite(<0.045 mm)were batched according to the chemical composition of forsterite(2MgO·SiO_(2)),wet milled,semi-dry molded and calcined at different temperatures.Then cylinder samples with diameter of 36 mm were prepared.The effects of the wet milling jar rotation speed,the calcination temperature and the anthracite addition on the properties of the samples were researched.The results show that:when the calcination temperature exceeds 1300℃,all the mineral phases have converted to the desired phases;with the increase of the rotation speed and the calcination temperature,the bulk density of the samples increases,the apparent porosity decreases and the compressive strength improves.By comprehensive consideration,400 r·min^(-1) and 1450℃ are taken as the optimal scheme.High addition of anthracite makes the samples light,so series of light-weight raw materials with uniformly distributed micro-pores can be gained.The light-weight raw materials achieved were used for insulation refractory castables,obtaining good application.展开更多
A novel process for fabricating an in-situ micro-porous on 316 L stainless steel was described.Aluminum films about 0.7-1.4 m in thickness were deposited on 316 L stainless steel surface by magnetron sputtering.The fi...A novel process for fabricating an in-situ micro-porous on 316 L stainless steel was described.Aluminum films about 0.7-1.4 m in thickness were deposited on 316 L stainless steel surface by magnetron sputtering.The films were then anodized in 0.3 M oxalic acid.Through appropriate chemical dissolution,the alumina film was removed and the underlying micro-porous 316 L with diameters ranging from 500 nm to 2.4m was obtained.The morphology of the porous 316 L surface was examined by scanning electron microscope.The results indicate that the thickness of aluminum films and the anodizing potential have a combined action on the formation of porous structure on 316 L surface.Then anodic current density could be affected evidently by the film thickness.The pores size increases obviously with the increasing of the anodizing potential,when the thickness of aluminum film was about 1.4m.展开更多
Recently a new kind stent,porous drug-eluting stent,has been developed to overcome the problems of bare metal stent(BMS)and drug-eluting stent(DES),and the clinic results reveal that it combined the advantage of BMS a...Recently a new kind stent,porous drug-eluting stent,has been developed to overcome the problems of bare metal stent(BMS)and drug-eluting stent(DES),and the clinic results reveal that it combined the advantage of BMS and DES.In this paper,a new method to fabricate surface pores on 316L stainless steel stent using anodic oxidation of aluminum mask film deposited by magnetron sputtering on 316L substrate was reported.The effect of experimental parameters,such as anodization time,anodization voltage,anodization solution and anodization temperature,on the pores'size distribution and density are investigated using SEM.It is found that the pores characterizations strongly depend on anodization time and pores expanding rate through AAO films and on stainless steel surface.展开更多
The DD33 superalloy with ultra-low nitrogen (N) content was prepared by vacuum induced melting, and the effect of N on micro-pores in the DD33 single crystal nickel-base superalloy during solidification and homogeniza...The DD33 superalloy with ultra-low nitrogen (N) content was prepared by vacuum induced melting, and the effect of N on micro-pores in the DD33 single crystal nickel-base superalloy during solidification and homogenization was investigated by in-situ X-ray computed tomography (XCT). Results indicate that the volume fraction of micro-pores, including shrinkage pores and gas pores, increases from 0.08% to 0.11% with increasing N content from 5 ppm to 45 ppm during solidification. Correspondingly, the level of micro-pores in the sample with high N content is higher than that in the sample with low N content during homogenization at 1,330 °C for different time periods. However, the evolution behaviors of gas pores is different from that of shrinkage pores during solidification and homogenization. The number of gas pores is obviously larger in the high N sample during solidification, while the number of shrinkage pores and gas pores is almost the same in both samples after 1 h homogenization. Quantitative results show that the annihilation of micro-pores is associated with bubble diffusion, while the growth behavior of micro-pores during further exposure is dominated by Kirkendall-Frenkel effect.展开更多
文摘The microstructure of the RE silicide alloy was studied by SEM. The feature of the phase and the distribution of Ca, P, Al were analyzed, especially the distribution of micro-cracks and its composition were determined. The result demonstrates that only a few phosphides contribute to the spontaneous crumbling of the RE silicide alloy by reacting with water and forming oxide or phosphorus oxide. The phosphorus content is not the critical factor of disintegration in the alloy studied.
文摘The reduction mechanism of Ir in the NaCl-KCl-IrCl3 molten salt was investigated by cyclic voltammetry and chronopotentiometry, and Ir film was deposited effectively on platinum in potentiostatic mode. The morphology and constitution of Ir film were examined by scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS） and X-ray diffraction （XRD）. It is found that the reduction mechanism of Ir（III） is a three-electron step and electro reaction is a reversible diffusion controlled process; the diffusion coefficients of Ir（III） at 1083, 1113, 1143 and 1183 K are 1.56×10-4, 2.23×10-4, 2.77×10-4 and 4.40×10-4 cm2/s, respectively, while the activation energy of the electrode reaction is 102.95 kJ/mol. The compacted Ir film reveals that the applied potential greatly affects the deposition of Ir, the thickness of Ir film deposited at the potential of reduction peak is the highest, the temperature of the molten salt also exerts an influence on deposition, the film formed at a lower temperature is thinner, but more micropores would occur on film when the temperature went too high.
基金The work was supported by Student Research Training Program of Henan University of Science and Technology in 2020(No.2020029).
文摘In order to develop new basic light-weight refractory raw materials,natural forsterite(<0.045 mm)and magnesite(<0.045 mm)were batched according to the chemical composition of forsterite(2MgO·SiO_(2)),wet milled,semi-dry molded and calcined at different temperatures.Then cylinder samples with diameter of 36 mm were prepared.The effects of the wet milling jar rotation speed,the calcination temperature and the anthracite addition on the properties of the samples were researched.The results show that:when the calcination temperature exceeds 1300℃,all the mineral phases have converted to the desired phases;with the increase of the rotation speed and the calcination temperature,the bulk density of the samples increases,the apparent porosity decreases and the compressive strength improves.By comprehensive consideration,400 r·min^(-1) and 1450℃ are taken as the optimal scheme.High addition of anthracite makes the samples light,so series of light-weight raw materials with uniformly distributed micro-pores can be gained.The light-weight raw materials achieved were used for insulation refractory castables,obtaining good application.
文摘A novel process for fabricating an in-situ micro-porous on 316 L stainless steel was described.Aluminum films about 0.7-1.4 m in thickness were deposited on 316 L stainless steel surface by magnetron sputtering.The films were then anodized in 0.3 M oxalic acid.Through appropriate chemical dissolution,the alumina film was removed and the underlying micro-porous 316 L with diameters ranging from 500 nm to 2.4m was obtained.The morphology of the porous 316 L surface was examined by scanning electron microscope.The results indicate that the thickness of aluminum films and the anodizing potential have a combined action on the formation of porous structure on 316 L surface.Then anodic current density could be affected evidently by the film thickness.The pores size increases obviously with the increasing of the anodizing potential,when the thickness of aluminum film was about 1.4m.
基金Science Found for Distinguished Yong Scholars of Heilongjiang Province(JC200901)Fundamental Research Funds for the Central Universities Project(HIT.NSRIF.2009030)Program of Excellent Team at Harbin Institute of Technology
文摘Recently a new kind stent,porous drug-eluting stent,has been developed to overcome the problems of bare metal stent(BMS)and drug-eluting stent(DES),and the clinic results reveal that it combined the advantage of BMS and DES.In this paper,a new method to fabricate surface pores on 316L stainless steel stent using anodic oxidation of aluminum mask film deposited by magnetron sputtering on 316L substrate was reported.The effect of experimental parameters,such as anodization time,anodization voltage,anodization solution and anodization temperature,on the pores'size distribution and density are investigated using SEM.It is found that the pores characterizations strongly depend on anodization time and pores expanding rate through AAO films and on stainless steel surface.
基金This work was financially supported by the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030001)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(No.2016ZT06G025).
文摘The DD33 superalloy with ultra-low nitrogen (N) content was prepared by vacuum induced melting, and the effect of N on micro-pores in the DD33 single crystal nickel-base superalloy during solidification and homogenization was investigated by in-situ X-ray computed tomography (XCT). Results indicate that the volume fraction of micro-pores, including shrinkage pores and gas pores, increases from 0.08% to 0.11% with increasing N content from 5 ppm to 45 ppm during solidification. Correspondingly, the level of micro-pores in the sample with high N content is higher than that in the sample with low N content during homogenization at 1,330 °C for different time periods. However, the evolution behaviors of gas pores is different from that of shrinkage pores during solidification and homogenization. The number of gas pores is obviously larger in the high N sample during solidification, while the number of shrinkage pores and gas pores is almost the same in both samples after 1 h homogenization. Quantitative results show that the annihilation of micro-pores is associated with bubble diffusion, while the growth behavior of micro-pores during further exposure is dominated by Kirkendall-Frenkel effect.
