Volume 44,Issue 6,2015 Table of Contents
2015, 44(6).
Abstract:
Solid oxide cells (SOC) that function reversibly in fuel cell (SOFC) and electrolytic (SOEC) modes offer the possibility of conversion and storage of energy through congruent production of electricity, hydrogen and syn-gas. Interconnect coating technologies for the solid oxide cells are particularly important. In this paper, the working environments of SOC at different operating modes were analyzed, and the available alloy materials, coating materials and coating techniques for SOC stack were reviewed.
Solid oxide cells (SOC) that function reversibly in fuel cell (SOFC) and electrolytic (SOEC) modes offer the possibility of conversion and storage of energy through congruent production of electricity, hydrogen and syn-gas. Interconnect coating technologies for the solid oxide cells are particularly important. In this paper, the working environments of SOC at different operating modes were analyzed, and the available alloy materials, coating materials and coating techniques for SOC stack were reviewed.
2 Friction and Wear Performances of Ni-P Coatings by Chemical Plating after Crystallization Treatment
2015, 44(6):1314-1319.
Abstract:
Amorphous Ni-P coating was prepared on the surface of ZL113 aluminum alloy by electroless plating. The surface morphologies, chemical element contents and phase compositions of the coating at different crystallization temperatures were characterized by SEM, EDS and XRD, respectively. The effect of crystallization temperature on coating micro-hardness was analyzed, and the wear mechanism was investigated with HSR-2M type reciprocation friction abrasion tester. The results show that the grain size of Ni-P coating increases with the increases of crystallization temperature, Ni based compounds are formed in the coating, and the hardness is the highest at the temperature of 350 oC. After 350 oC, if the crystallization temperature increases continuously, and the grain size increases a little fast a reverse effect of Hall-Petch with the intensity of Ni diffraction peak increasing is shown. The friction coefficient increases first and then decreases with the increases of crystallization temperature. The friction coefficient is minimum, and the wear resistance is the best at 350 oC. The wear mechanism is abrasive wear, abrasive＋adhesive wear and abrasive wear at the crystallization temperatures less than 350 oC, 350 oC, more than 350 oC, respectively
Amorphous Ni-P coating was prepared on the surface of ZL113 aluminum alloy by electroless plating. The surface morphologies, chemical element contents and phase compositions of the coating at different crystallization temperatures were characterized by SEM, EDS and XRD, respectively. The effect of crystallization temperature on coating micro-hardness was analyzed, and the wear mechanism was investigated with HSR-2M type reciprocation friction abrasion tester. The results show that the grain size of Ni-P coating increases with the increases of crystallization temperature, Ni based compounds are formed in the coating, and the hardness is the highest at the temperature of 350 oC. After 350 oC, if the crystallization temperature increases continuously, and the grain size increases a little fast a reverse effect of Hall-Petch with the intensity of Ni diffraction peak increasing is shown. The friction coefficient increases first and then decreases with the increases of crystallization temperature. The friction coefficient is minimum, and the wear resistance is the best at 350 oC. The wear mechanism is abrasive wear, abrasive＋adhesive wear and abrasive wear at the crystallization temperatures less than 350 oC, 350 oC, more than 350 oC, respectively
2015, 44(6):1320-1325.
Abstract:
The pure and Fe-containing nanocrystalline layers were fabricated on the surface of 2024 Al alloy by surface mechanical attrition treatment (SMAT) using ceramic balls and steel balls, respectively. The friction and wear properties of 2024 Al alloy before and after SMAT were investigated by sliding against a GCr15 steel ball of 5 mm in diameter at a load of 1.5 N. The results demonstrate that the surface nanocrystalline layers with average grain sizes of 49.2 and 52.1 nm can be obtained by using ceramic balls and steel balls, respectively, when treated for 30 min. Moreover, a 5 μm thick surface layer containing Fe is also introduced into the Al nanocrystalline surface when treated using steel balls. The wear resistance of 2024 Al alloy is improved due to the combination of grain refinement, increased hardness and lubrication effect of iron-containing layer
The pure and Fe-containing nanocrystalline layers were fabricated on the surface of 2024 Al alloy by surface mechanical attrition treatment (SMAT) using ceramic balls and steel balls, respectively. The friction and wear properties of 2024 Al alloy before and after SMAT were investigated by sliding against a GCr15 steel ball of 5 mm in diameter at a load of 1.5 N. The results demonstrate that the surface nanocrystalline layers with average grain sizes of 49.2 and 52.1 nm can be obtained by using ceramic balls and steel balls, respectively, when treated for 30 min. Moreover, a 5 μm thick surface layer containing Fe is also introduced into the Al nanocrystalline surface when treated using steel balls. The wear resistance of 2024 Al alloy is improved due to the combination of grain refinement, increased hardness and lubrication effect of iron-containing layer
2015, 44(6):1345-1350.
Abstract:
The microstructural evolution behavior of one kind of nickel-based single crystal superalloy aged at elevated temperature was investigated. The short-term exposures were performed at 980, 1050 and 1100 oC for 20, 50 and 100 h, and long time agings were carried on from 200 to 800 h at 1100 oC. Microstructure observation was carried out by field emission scanning electron microscope (FE-SEM). Electron Probe Micro Analyzer (EPMA) was employed to determine the composition of TCP phase. The microhardness was tested to all the aged specimens. The results show that in short-term aging, the coarsening of γ' particles in this superalloy follows the standard r3-t kinetics of diffusion-controlled particle growth and coarsening rate constants were calculated. During long-term aging, for samples exposed for 400 h at 1100 oC, the rafted structure has developed completely and TCP precipitates has formed. The composition of TCP phase is mainly composed of Re and W. In addition, under some conditions of short time aging, TCP phases are found to precipitate from the alloy. The microhardnesses of all the aged specimens exhibit no obvious changes
The microstructural evolution behavior of one kind of nickel-based single crystal superalloy aged at elevated temperature was investigated. The short-term exposures were performed at 980, 1050 and 1100 oC for 20, 50 and 100 h, and long time agings were carried on from 200 to 800 h at 1100 oC. Microstructure observation was carried out by field emission scanning electron microscope (FE-SEM). Electron Probe Micro Analyzer (EPMA) was employed to determine the composition of TCP phase. The microhardness was tested to all the aged specimens. The results show that in short-term aging, the coarsening of γ' particles in this superalloy follows the standard r3-t kinetics of diffusion-controlled particle growth and coarsening rate constants were calculated. During long-term aging, for samples exposed for 400 h at 1100 oC, the rafted structure has developed completely and TCP precipitates has formed. The composition of TCP phase is mainly composed of Re and W. In addition, under some conditions of short time aging, TCP phases are found to precipitate from the alloy. The microhardnesses of all the aged specimens exhibit no obvious changes
Wu Ziping
,
Zhang Weibo
,
Yin Yanhong
,
Li Yesheng
,
Chen Yisheng
,
Yang Jiangao
,
Liu Yong
,
Xu Qianfeng
2015, 44(6):1351-1356.
Abstract:
This study investigated different dispersed double-walled carbon nanotubes (DWCNTs) as supports for depositing Pt nanoparticles. Homogenously dispersed Pt particles with sizes of approximately 2.08 nm were obtained on DWCNT surfaces. The size and the dispersion state of the Pt particles on the DWCNT support exhibit stronger hydrogen desorption/adsorption peaks and higher electrochemical activity (electric current density is 0.022 A·cm?2 and electrochemical specific surface area is 86.38 m2·g-1) compared to the other Pt/DWCNT catalysts. Further analysis shows that the concentration of the support in the suspension significantly affects the size and the uniformity of the generated Pt particles. The Pt particles of the size and the state on the supports can realize a Pt catalyst with high electrochemical activity and low cost.
This study investigated different dispersed double-walled carbon nanotubes (DWCNTs) as supports for depositing Pt nanoparticles. Homogenously dispersed Pt particles with sizes of approximately 2.08 nm were obtained on DWCNT surfaces. The size and the dispersion state of the Pt particles on the DWCNT support exhibit stronger hydrogen desorption/adsorption peaks and higher electrochemical activity (electric current density is 0.022 A·cm?2 and electrochemical specific surface area is 86.38 m2·g-1) compared to the other Pt/DWCNT catalysts. Further analysis shows that the concentration of the support in the suspension significantly affects the size and the uniformity of the generated Pt particles. The Pt particles of the size and the state on the supports can realize a Pt catalyst with high electrochemical activity and low cost.
2015, 44(6):1363-1368.
Abstract:
Thin-walled specimens of the DD6 single crystal superalloy with different thicknesses were prepared using Bridgman method. The effect of section size on the microstructure of the thin-walled specimens of DD6 single crystal superalloy was investigated. The results show that with the reduction of section size, the primary dendrite arm spacing and the eutectic percent of the thin-walled specimen as-cast first decrease and then increase, and the average size of γ’ phase in the dendritic core of the thin-walled specimen after heat treatment declines gradually. The appropriate decrease in section size can reduce the degree of interdendritic segregation, but when the section size is reduced to 0.5 mm, the degree of interdendritic segregation increases
Thin-walled specimens of the DD6 single crystal superalloy with different thicknesses were prepared using Bridgman method. The effect of section size on the microstructure of the thin-walled specimens of DD6 single crystal superalloy was investigated. The results show that with the reduction of section size, the primary dendrite arm spacing and the eutectic percent of the thin-walled specimen as-cast first decrease and then increase, and the average size of γ’ phase in the dendritic core of the thin-walled specimen after heat treatment declines gradually. The appropriate decrease in section size can reduce the degree of interdendritic segregation, but when the section size is reduced to 0.5 mm, the degree of interdendritic segregation increases
2015, 44(6):1369-1373.
Abstract:
The segregation behavior and the deformation mechanism of Ti14, a new typical burn resistant α+Ti2Cu alloy were investigated, during semi-solid forging at different temperatures. The results reveal that semi-solid temperature will affect the content and the distribution of liquid phase evidently. Upon increasing of temperature, the liquid phase distribution transforms from discontinuity to continuity at grain boundaries, and finally a type of net-structure is formed. Moreover, the macro-segregation of liquid and solid phases occurs during the semi-solid forging, which leads to a change of the main deformation mechanism from center to edge of the sample. The relationship of macro-segregation of liquid/solid phases and the main deformation mechanism was also discussed by a phenomenological model.
The segregation behavior and the deformation mechanism of Ti14, a new typical burn resistant α+Ti2Cu alloy were investigated, during semi-solid forging at different temperatures. The results reveal that semi-solid temperature will affect the content and the distribution of liquid phase evidently. Upon increasing of temperature, the liquid phase distribution transforms from discontinuity to continuity at grain boundaries, and finally a type of net-structure is formed. Moreover, the macro-segregation of liquid and solid phases occurs during the semi-solid forging, which leads to a change of the main deformation mechanism from center to edge of the sample. The relationship of macro-segregation of liquid/solid phases and the main deformation mechanism was also discussed by a phenomenological model.
Tan Guoxin
,
Wang Hang
,
Ning Chengyun
,
Tan Ying
,
Zhou Lei
,
Liao Jingwen
,
Chen Xiaofeng
,
Yu Peng
2015, 44(6):1379-1384.
Abstract:
Titanium plates were grafted with octadecyl-trichlorosilane (OTS) after activated by piranha solution (H2SO4:H2O2=7:3 in volume ratio) and then the Ti-OTS was irradiated by UV light. The influence of UV irradiation on the calcium phosphate coating on different titanium samples obtained by electrochemical deposition was discussed. The OTS self-assembled monolayer and calcium phosphate coatings on titanium were characterized by fourier transform infrared spectroscopy (FTIR), contact angle tester, X-ray diffractometer (XRD) and field emission scanning electron microscopy (FE-SEM). The results show that the water contact angle of Ti-OTS is decreased from 109.8±2.1° to 63.4±1.8° after UV irradiation, and the surface free energy increases from 37.50 mJ·m--2 to 45.18 mJ·m--2. Highly homogeneous and ordered flower-like hydroxyapatite crystals are distributed on Ti-OTS-UV, which could be expected to improve the stability of the implant material
Titanium plates were grafted with octadecyl-trichlorosilane (OTS) after activated by piranha solution (H2SO4:H2O2=7:3 in volume ratio) and then the Ti-OTS was irradiated by UV light. The influence of UV irradiation on the calcium phosphate coating on different titanium samples obtained by electrochemical deposition was discussed. The OTS self-assembled monolayer and calcium phosphate coatings on titanium were characterized by fourier transform infrared spectroscopy (FTIR), contact angle tester, X-ray diffractometer (XRD) and field emission scanning electron microscopy (FE-SEM). The results show that the water contact angle of Ti-OTS is decreased from 109.8±2.1° to 63.4±1.8° after UV irradiation, and the surface free energy increases from 37.50 mJ·m--2 to 45.18 mJ·m--2. Highly homogeneous and ordered flower-like hydroxyapatite crystals are distributed on Ti-OTS-UV, which could be expected to improve the stability of the implant material
2015, 44(6):1385-1390.
Abstract:
Uniaxial tensile tests for pure molybdenum sheets with thickness of 2.0 mm were conducted in a temperature range between 25 and 870 °C, and the finite element model for hot deep drawing of molybdenum plate was established. Based on the contrastive analysis of FEM and experiments, the relationship between friction coefficient and temperature was confirmed, and the effects of forming temperatures, lubricating conditions, blank-holder gap and die dimensions on deep drawing process were investigated, and then the vacuum hot deep drawing tests were carried out with optimized process parameters. The results indicate that lubrication has the most prominent effect on the deep-drawing process, followed by the forming temperature. The limiting drawing ratio can be raised up to 1.94 with the optimum parameters including forming temperature 870 °C, drawing speed 30 mm/min and blank-holder gap 2.5 mm under lubricated condition
Uniaxial tensile tests for pure molybdenum sheets with thickness of 2.0 mm were conducted in a temperature range between 25 and 870 °C, and the finite element model for hot deep drawing of molybdenum plate was established. Based on the contrastive analysis of FEM and experiments, the relationship between friction coefficient and temperature was confirmed, and the effects of forming temperatures, lubricating conditions, blank-holder gap and die dimensions on deep drawing process were investigated, and then the vacuum hot deep drawing tests were carried out with optimized process parameters. The results indicate that lubrication has the most prominent effect on the deep-drawing process, followed by the forming temperature. The limiting drawing ratio can be raised up to 1.94 with the optimum parameters including forming temperature 870 °C, drawing speed 30 mm/min and blank-holder gap 2.5 mm under lubricated condition
2015, 44(6):1407-1412.
Abstract:
A new method was presented from the view of mechanics to prevent welding hot cracking for aluminum alloy by employing transverse ultrasonic during welding. The mechanical condition of welding hot cracking was discussed. The material-mechanical properties matching model within brittle temperature region (BTR) metals was established and the plastic flow and the variation of the strain field in welds by transverse ultrasonic were analyzed numerically. The simulation results show that the transverse ultrasonic impact produces transverse compressive plastic strain in BTR metal, and the plastic deformation is transferred to the weld centre through the metal within BTR. With the ultrasonic load amplitude increasing, the compressive stress in weld centre increases. Experiment was carried out through the ultrasonic extrusion in BTR area. It is indicated that the simulation results and the experiment results are in good accordance, which proves the reliability of the new method
A new method was presented from the view of mechanics to prevent welding hot cracking for aluminum alloy by employing transverse ultrasonic during welding. The mechanical condition of welding hot cracking was discussed. The material-mechanical properties matching model within brittle temperature region (BTR) metals was established and the plastic flow and the variation of the strain field in welds by transverse ultrasonic were analyzed numerically. The simulation results show that the transverse ultrasonic impact produces transverse compressive plastic strain in BTR metal, and the plastic deformation is transferred to the weld centre through the metal within BTR. With the ultrasonic load amplitude increasing, the compressive stress in weld centre increases. Experiment was carried out through the ultrasonic extrusion in BTR area. It is indicated that the simulation results and the experiment results are in good accordance, which proves the reliability of the new method
2015, 44(6):1418-1422.
Abstract:
The FeCoCrNiBx high-entropy alloy coatings were prepared by laser cladding. The effect of boron addition on microstructure, hardness and wear resistance of FeCoCrNiBx high-entropy alloy coating were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), hardness and wear testers. The results show that with the boron addition increasing, the structure of alloys change from fcc structure to fcc structure with M3B phase precipitation, and M3B phase are mainly borides of Cr and Fe. Meanwhile, the granular and short rod-like M3B phase is precipitated in the coatings. And a blocky M3B phase forms with boron addition. Microhardness and wear resistance are significantly enhanced by the formation M3B phase. The microhardness increases from 4470 to 8480 MPa, and the wear-loss of FeCoCrNiBx high-entropy alloy coating decrease with boron addition
The FeCoCrNiBx high-entropy alloy coatings were prepared by laser cladding. The effect of boron addition on microstructure, hardness and wear resistance of FeCoCrNiBx high-entropy alloy coating were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), hardness and wear testers. The results show that with the boron addition increasing, the structure of alloys change from fcc structure to fcc structure with M3B phase precipitation, and M3B phase are mainly borides of Cr and Fe. Meanwhile, the granular and short rod-like M3B phase is precipitated in the coatings. And a blocky M3B phase forms with boron addition. Microhardness and wear resistance are significantly enhanced by the formation M3B phase. The microhardness increases from 4470 to 8480 MPa, and the wear-loss of FeCoCrNiBx high-entropy alloy coating decrease with boron addition
2015, 44(6):1427-1431.
Abstract:
Microstructure and properties of the Cu-5.2Ni-1.2Si and Cu-5.2Ni-1.5Al-1.2Si alloy were studied by optical microscope, Vickers hardness tester, two-arm electricity bridge, scanning electron microscope and transmission electron microscope. Results show that the developed dendrite appears in the casting ingot, which can be divided into dendrite area, non-equilibrium precipitates and the middle transition region. The dendrite area is rich in Cu element, the precipitates are rich in Ni and Si elements, and the Al element is distributed in the ingot evenly. After the appropriate thermo-mechanical treatment, the hardness of Cu-5.2Ni-1.5Al-1.2Si alloy is higher than that of Cu-5.2Ni-1.2Si alloy, and Ni2Si precipitates contribute to the main strength. Al element promotes the Ni2Si precipitation process. A new phase of Ni3Al is formed, which also improves the strength of the alloy effectively. Ordering transformation appears in the early state of ageing treatment, and the high strength is attributed to the precipitation particles. The designed alloy exhibits good anti-over aged capability
Microstructure and properties of the Cu-5.2Ni-1.2Si and Cu-5.2Ni-1.5Al-1.2Si alloy were studied by optical microscope, Vickers hardness tester, two-arm electricity bridge, scanning electron microscope and transmission electron microscope. Results show that the developed dendrite appears in the casting ingot, which can be divided into dendrite area, non-equilibrium precipitates and the middle transition region. The dendrite area is rich in Cu element, the precipitates are rich in Ni and Si elements, and the Al element is distributed in the ingot evenly. After the appropriate thermo-mechanical treatment, the hardness of Cu-5.2Ni-1.5Al-1.2Si alloy is higher than that of Cu-5.2Ni-1.2Si alloy, and Ni2Si precipitates contribute to the main strength. Al element promotes the Ni2Si precipitation process. A new phase of Ni3Al is formed, which also improves the strength of the alloy effectively. Ordering transformation appears in the early state of ageing treatment, and the high strength is attributed to the precipitation particles. The designed alloy exhibits good anti-over aged capability
2015, 44(6):1432-1438.
Abstract:
According to the creep deformation of Babbitt SnSb11Cu6 of oil-film bearing in operation, a creep test method of SnSb11Cu6 was designed and the creep test of SnSb11Cu6 was carried out. The relationships of stress temperature, time, strain and strain rate were analyzed, and then the creep mechanical properties of SnSb11Cu6 were obtained. Meanwhile, four kinds of creep models were compared based on the experimental data. A creep model of SnSb11Cu6 was established based on McVetty formula and Dorn formula, whose relative error is only 0.97%. The creep specimen was simulated by ANSYS, and the relative error between the simulation value and the calculated value of SnSb11Cu6 creep model in the steady state creep stage is only 0.77%. It is concluded that the creep model of SnSb11Cu6 has high accuracy on describing its creep characteristics and can provide theoretical and experimental supports for life prediction of Babbitt SnSb11Cu6 of oil-film bearing bushing
According to the creep deformation of Babbitt SnSb11Cu6 of oil-film bearing in operation, a creep test method of SnSb11Cu6 was designed and the creep test of SnSb11Cu6 was carried out. The relationships of stress temperature, time, strain and strain rate were analyzed, and then the creep mechanical properties of SnSb11Cu6 were obtained. Meanwhile, four kinds of creep models were compared based on the experimental data. A creep model of SnSb11Cu6 was established based on McVetty formula and Dorn formula, whose relative error is only 0.97%. The creep specimen was simulated by ANSYS, and the relative error between the simulation value and the calculated value of SnSb11Cu6 creep model in the steady state creep stage is only 0.77%. It is concluded that the creep model of SnSb11Cu6 has high accuracy on describing its creep characteristics and can provide theoretical and experimental supports for life prediction of Babbitt SnSb11Cu6 of oil-film bearing bushing
2015, 44(6):1451-1454.
Abstract:
The strengthening mechanism of the large straining CP Al processed by rolling driven-ECA (Equal Channel Angular) was investigated. A theoretical calculation based on XRD analysis and Taylor equation indicates that the dislocation density of the large straining CP Al by rolling driven-ECA is very low. Low angle grain boundary and high angle grain boundary were measured by a crystal micro area orientation analysis technique and the results demonstrate that the low angle grain boundary is much more. Strengthening mechanisms of the large straining CP Al were quantitatively calculated based on the Hall-Petch relationships, and it is concluded that the strengthening mainly comes from the low angle grain boundary
The strengthening mechanism of the large straining CP Al processed by rolling driven-ECA (Equal Channel Angular) was investigated. A theoretical calculation based on XRD analysis and Taylor equation indicates that the dislocation density of the large straining CP Al by rolling driven-ECA is very low. Low angle grain boundary and high angle grain boundary were measured by a crystal micro area orientation analysis technique and the results demonstrate that the low angle grain boundary is much more. Strengthening mechanisms of the large straining CP Al were quantitatively calculated based on the Hall-Petch relationships, and it is concluded that the strengthening mainly comes from the low angle grain boundary
2015, 44(6):1455-1458.
Abstract:
The composite TiAlCN films were deposited by vacuum arc ion plating on GCr15 rings at 175 oC. The properties of the films were characterized by SEM,?EPMA,?XRD,?adhesion?tester,?nano-hardness?tester and UMT-2 high temperature tribometer. The results indicate that the surface of the films is smooth and dense without any obvious pores. There are a certain number of droplets on the surface of films. The thickness of the films is about 2 μm. The fcc structure of TiN is found in the films. The grain size of the films is from 10 to 30 nm. With the addition of C element into the film, (Ti0.5,Al0.5)N peak in XRD patterns appears in width. After adding C into TiAlN, the adhesion of the films declines. However, the adhesion increases slightly along with the increase of the C content, but Al and Ti ratio does not change significantly. Besides, the hardness and elastic modulus increase first and then decreases, and the friction coefficient is always declined
The composite TiAlCN films were deposited by vacuum arc ion plating on GCr15 rings at 175 oC. The properties of the films were characterized by SEM,?EPMA,?XRD,?adhesion?tester,?nano-hardness?tester and UMT-2 high temperature tribometer. The results indicate that the surface of the films is smooth and dense without any obvious pores. There are a certain number of droplets on the surface of films. The thickness of the films is about 2 μm. The fcc structure of TiN is found in the films. The grain size of the films is from 10 to 30 nm. With the addition of C element into the film, (Ti0.5,Al0.5)N peak in XRD patterns appears in width. After adding C into TiAlN, the adhesion of the films declines. However, the adhesion increases slightly along with the increase of the C content, but Al and Ti ratio does not change significantly. Besides, the hardness and elastic modulus increase first and then decreases, and the friction coefficient is always declined
2015, 44(6):1459-1464.
Abstract:
The comparison studies on performance differences between traditional Ti-based electrode of Ti/SnO2+Sb2O4/PbO2 and novel Ti/Al composited substrate electrode of Ti/Al/Ti/SnO2+Sb2O4/PbO2 were provided. Through changing the sintering temperature of Ti/Al composited substrate, the optimum process conditions for preparing this novel electrode were obtained. The structure and morphology of Ti/Al bonding interface layers and active surface β-PbO2 coatings were characterized by SEM, EDS and XRD. Combined with electrochemical testing technology, the effect of sintering temperature on electrochemical properties and lifetime was analyzed. The results show that this novel Ti/Al composited substrate electrode, whose electrical resistivity is only one tenth of pure Ti substrate, exhibits a smaller grain size, larger surface active areas and better electrochemical properties compared to pure Ti-based electrode. Intermetallic of TiAl3 in Ti/Al composite interface is obtained at the sintering temperature of 540 °C, and it exhibits the best performance. The polarization resistance and polarization potential of Ti/Al composited substrate electrodes decline by 43% and 18%, respectively. The potential decreases by 320 mV compared to Ti-based electrode under the condition of 0.2 A/cm2 current density. This electrode has the best exchange-current density j0 and the lowest oxygen overvoltage η by strong polarization measurement. And the industrial service lifetime of this novel electrode reaches 10.4 years, 50% higher than that of traditional Ti-based electrodes
The comparison studies on performance differences between traditional Ti-based electrode of Ti/SnO2+Sb2O4/PbO2 and novel Ti/Al composited substrate electrode of Ti/Al/Ti/SnO2+Sb2O4/PbO2 were provided. Through changing the sintering temperature of Ti/Al composited substrate, the optimum process conditions for preparing this novel electrode were obtained. The structure and morphology of Ti/Al bonding interface layers and active surface β-PbO2 coatings were characterized by SEM, EDS and XRD. Combined with electrochemical testing technology, the effect of sintering temperature on electrochemical properties and lifetime was analyzed. The results show that this novel Ti/Al composited substrate electrode, whose electrical resistivity is only one tenth of pure Ti substrate, exhibits a smaller grain size, larger surface active areas and better electrochemical properties compared to pure Ti-based electrode. Intermetallic of TiAl3 in Ti/Al composite interface is obtained at the sintering temperature of 540 °C, and it exhibits the best performance. The polarization resistance and polarization potential of Ti/Al composited substrate electrodes decline by 43% and 18%, respectively. The potential decreases by 320 mV compared to Ti-based electrode under the condition of 0.2 A/cm2 current density. This electrode has the best exchange-current density j0 and the lowest oxygen overvoltage η by strong polarization measurement. And the industrial service lifetime of this novel electrode reaches 10.4 years, 50% higher than that of traditional Ti-based electrodes
2015, 44(6):1465-1468.
Abstract:
The non-stoichiometric Zr0.9Ti0.1V2.2 alloy was designed and the melt-spun technology was used in this work to improve the hydrogenation kinetics of Laves phase Zr-Ti-V alloys. The microstructure, phase constitution, hydrogenation kinetics, PCT characteristics and the thermodynamics parameters of melt-spun ribbons were investigated. The relationship between microstructure and hydrogen storage properties of non-stoichiometric alloys was further discussed. The results show that C15 type ZrV2 phase and V-bcc phase are the dominant phases in the alloy, and melt-spun can eliminate the residual α-Zr phase of peritectic reaction in the as-cast alloy. The hydrogenation kinetics is fast in melt-spun alloy, but the hydrogen absorption capacity decreases due to the shrink of cell volume
The non-stoichiometric Zr0.9Ti0.1V2.2 alloy was designed and the melt-spun technology was used in this work to improve the hydrogenation kinetics of Laves phase Zr-Ti-V alloys. The microstructure, phase constitution, hydrogenation kinetics, PCT characteristics and the thermodynamics parameters of melt-spun ribbons were investigated. The relationship between microstructure and hydrogen storage properties of non-stoichiometric alloys was further discussed. The results show that C15 type ZrV2 phase and V-bcc phase are the dominant phases in the alloy, and melt-spun can eliminate the residual α-Zr phase of peritectic reaction in the as-cast alloy. The hydrogenation kinetics is fast in melt-spun alloy, but the hydrogen absorption capacity decreases due to the shrink of cell volume
Lai Yunjin
,
Zhang Pingxiang
,
Xin Shewei
,
Ma Fanjiao
,
Feng Yong
,
Liu Xianghong
,
Kou Hongchao
,
Zhao Yongqing
2015, 44(6):1469-1463.
Abstract:
The microstructure and mechanical properties of WSTi3515S alloy after various heat treatments and thermal exposure treatments were researched. The results indicate that different heat treatments below 850 oC have little effect on microstructure and mechanical properties of the alloy. When the heat treatment temperature is 950 oC, the microstructure of the alloy obviously changes; however, the room-temperature mechanical properties have no change, which indicates that WSTi3515S alloy holds better microstructure and performance stability. After the heat treated samples are thermal exposed at 570 oC for 100 h, the strength of the alloy increases and the elongation sharply decreases. During the thermal exposure process, there is a small quality of precipitations in the alloy and they mainly distribute at grain boundaries. The precipitation at the grain boundaries is the main reason for the decreased elongation of the alloy after thermal exposure
The microstructure and mechanical properties of WSTi3515S alloy after various heat treatments and thermal exposure treatments were researched. The results indicate that different heat treatments below 850 oC have little effect on microstructure and mechanical properties of the alloy. When the heat treatment temperature is 950 oC, the microstructure of the alloy obviously changes; however, the room-temperature mechanical properties have no change, which indicates that WSTi3515S alloy holds better microstructure and performance stability. After the heat treated samples are thermal exposed at 570 oC for 100 h, the strength of the alloy increases and the elongation sharply decreases. During the thermal exposure process, there is a small quality of precipitations in the alloy and they mainly distribute at grain boundaries. The precipitation at the grain boundaries is the main reason for the decreased elongation of the alloy after thermal exposure
2015, 44(6):1485-1488.
Abstract:
Highly-ordered TiO2 nanotube arrays were synthesized by anodic oxidation of titanium foil in ethylene glycol electrolyte. The morphology and element composition of the TiO2 nanotubes were characterized by SEM and EDX, respectively. The growth?process of the TiO2 nanotubes was also discussed. The results indicate that the formation of TiO2 nanotubes is a transformation?process from nanoporous structure to individual nanotube arrays structure. Moreover, efficient hydrogen production with low?energy?consumption is achieved using TiO2 nanotubes as photoanode in the two-compartment photoelectrochemical (PEC) cell, in which the photovoltage of TiO2 cooperates with a chemical bias produced by the pH difference between acidic electrolyte and alkaline electrolyte to reach the voltage of water splitting. Without any external applied voltage or sacrificial agent, the photocurrent density TiO2 nanotubes is 6.51 mA/cm2 and the hydrogen production rate of 108.9 μmol/cm2 is obtained under solar light illumination for 1 h
Highly-ordered TiO2 nanotube arrays were synthesized by anodic oxidation of titanium foil in ethylene glycol electrolyte. The morphology and element composition of the TiO2 nanotubes were characterized by SEM and EDX, respectively. The growth?process of the TiO2 nanotubes was also discussed. The results indicate that the formation of TiO2 nanotubes is a transformation?process from nanoporous structure to individual nanotube arrays structure. Moreover, efficient hydrogen production with low?energy?consumption is achieved using TiO2 nanotubes as photoanode in the two-compartment photoelectrochemical (PEC) cell, in which the photovoltage of TiO2 cooperates with a chemical bias produced by the pH difference between acidic electrolyte and alkaline electrolyte to reach the voltage of water splitting. Without any external applied voltage or sacrificial agent, the photocurrent density TiO2 nanotubes is 6.51 mA/cm2 and the hydrogen production rate of 108.9 μmol/cm2 is obtained under solar light illumination for 1 h
2015, 44(6):1494-1498.
Abstract:
To obtain better microstructures and improve refining performance, a new aluminum grain refiner Al-Ti-B-RE master alloy was prepared by a mix molten-pure titanium method. The results show that there are small blocks of Al3Ti and Ti2A120RE phases in the Al-Ti-B-RE master alloys prepared at optimal temperatures while there are large flakes at high temperature. The morphology, distribution and quantity of second phases of Al-Ti-B-RE master alloys and refining effects and nucleating potentials were studied by XRD, SEM and OM. It is indicated that the morphology, distribution and quantity of second phase particles of Al-Ti-B-RE master alloys have an important influence on the refining effects. A better refining effect could be obtained with the smaller disregistry between nucleation and the substrate in favor of promoting nucleation
To obtain better microstructures and improve refining performance, a new aluminum grain refiner Al-Ti-B-RE master alloy was prepared by a mix molten-pure titanium method. The results show that there are small blocks of Al3Ti and Ti2A120RE phases in the Al-Ti-B-RE master alloys prepared at optimal temperatures while there are large flakes at high temperature. The morphology, distribution and quantity of second phases of Al-Ti-B-RE master alloys and refining effects and nucleating potentials were studied by XRD, SEM and OM. It is indicated that the morphology, distribution and quantity of second phase particles of Al-Ti-B-RE master alloys have an important influence on the refining effects. A better refining effect could be obtained with the smaller disregistry between nucleation and the substrate in favor of promoting nucleation
2015, 44(6):1517-1521.
Abstract:
In order to investigate the feasibility of laser shock peening (LSP) on the components suffering high temperature in work, the thermal stability of LSP effects on GH4133 nickel-based superalloy were studied. GH4133 nickel-based superalloy samples were treated by laser shock peening and laser shock peening+annealing separately. The thermal stability was examined by scanning electron microscopy (SEM), microhardness and residual stress tests. High-temperature fatigue of turbine blades was tested and the mechanism of fatigue life improvement was also discussed. Results show that high-amplitude residual compressive stress and grain refinement are generated, and precipitated phase of GH4133 alloy treated by LSP has a great impact on thermal stability for the refined grains. On the other hand, stress concentration slows up and distributes uniformly. Both of microstructure and residual compressive stress are propitious to fatigue life
In order to investigate the feasibility of laser shock peening (LSP) on the components suffering high temperature in work, the thermal stability of LSP effects on GH4133 nickel-based superalloy were studied. GH4133 nickel-based superalloy samples were treated by laser shock peening and laser shock peening+annealing separately. The thermal stability was examined by scanning electron microscopy (SEM), microhardness and residual stress tests. High-temperature fatigue of turbine blades was tested and the mechanism of fatigue life improvement was also discussed. Results show that high-amplitude residual compressive stress and grain refinement are generated, and precipitated phase of GH4133 alloy treated by LSP has a great impact on thermal stability for the refined grains. On the other hand, stress concentration slows up and distributes uniformly. Both of microstructure and residual compressive stress are propitious to fatigue life
2015, 44(6):1522-1526.
Abstract:
Plastic deformation behavior and the features of internal shear bands in Pd79Cu4Au2Si10P5 bulk metallic glasses were investigated. The results show that the samples with diameters of 1 mm, 2 mm and 3 mm all have lager plastic deformation and the plastic strain is about 13%, 10% and 8%, respectively. In addition, the samples with different diameters have distinctly different serrated flows on the engineering stress-strain curves. The serrated-flow amplitude of the specimen with diameter of 2 mm is the largest, and the smallest serrated-flow amplitude is obtained in the specimen with diameter of 3 mm. The serrated-flow space of the specimens with diameters of 1 and 3 mm is smaller than that of the specimen with diameter of 2 mm. The results observed by optical microscopy show that, with the increase of sample size, the density of the internal primary shear bands decreases, but the density of the secondary shear bands increases. Further studies by scanning electron microscopy show that the thickness of primary shear band increases with the increase of sample size
Plastic deformation behavior and the features of internal shear bands in Pd79Cu4Au2Si10P5 bulk metallic glasses were investigated. The results show that the samples with diameters of 1 mm, 2 mm and 3 mm all have lager plastic deformation and the plastic strain is about 13%, 10% and 8%, respectively. In addition, the samples with different diameters have distinctly different serrated flows on the engineering stress-strain curves. The serrated-flow amplitude of the specimen with diameter of 2 mm is the largest, and the smallest serrated-flow amplitude is obtained in the specimen with diameter of 3 mm. The serrated-flow space of the specimens with diameters of 1 and 3 mm is smaller than that of the specimen with diameter of 2 mm. The results observed by optical microscopy show that, with the increase of sample size, the density of the internal primary shear bands decreases, but the density of the secondary shear bands increases. Further studies by scanning electron microscopy show that the thickness of primary shear band increases with the increase of sample size
2015, 44(6):1541-1545.
Abstract:
A stannate conversion coating was prepared on the AZ91D magnesium alloy surface by a chemical conversion process. The coating performances were tested by CuSO4 drip experiment, EIS, Tafel, SEM and XRD. The effects of some organic additives including tartaric?acid, citric?acid, phytic?acid, EDTA, and sodium?dodecyl?sulfate on the coating corrosion resistance were studied. The results show that the drip time is increased from 35 to 86 s by adding sodium?dodecyl?sulfate and it could improve the corrosion resistance of the film to a large extent. The morphology of the membrane layer mainly contains MgSn(OH)6 and Mg(OH)2 which is granular-bonded
A stannate conversion coating was prepared on the AZ91D magnesium alloy surface by a chemical conversion process. The coating performances were tested by CuSO4 drip experiment, EIS, Tafel, SEM and XRD. The effects of some organic additives including tartaric?acid, citric?acid, phytic?acid, EDTA, and sodium?dodecyl?sulfate on the coating corrosion resistance were studied. The results show that the drip time is increased from 35 to 86 s by adding sodium?dodecyl?sulfate and it could improve the corrosion resistance of the film to a large extent. The morphology of the membrane layer mainly contains MgSn(OH)6 and Mg(OH)2 which is granular-bonded
2015, 44(6):1546-1549.
Abstract:
The effect of multi-electromagnetic field on the K417 superalloy ingots solidification microstructure has been studied. The results show that during the solidification process of superalloy vacuum casting, the application of the multi-electromagnetic field, composed of rotary electromagnetic field with 60 A current and steady DC electromagnetic field with 290 A current, can increase the scope and effect of rotary electromagnetic field as well as improve the feeding conditions of ingots. The reason can be attributed to that the electromagnetic brake generated by DC electromagnetic field can suppress effectively the metal surface fluctuation generated by rotary electromagnetic field. As a result, the fine equiaxed grain fraction of ingots can be increased to 96 % and the shrinkage porosity of ingots can be greatly reduced
The effect of multi-electromagnetic field on the K417 superalloy ingots solidification microstructure has been studied. The results show that during the solidification process of superalloy vacuum casting, the application of the multi-electromagnetic field, composed of rotary electromagnetic field with 60 A current and steady DC electromagnetic field with 290 A current, can increase the scope and effect of rotary electromagnetic field as well as improve the feeding conditions of ingots. The reason can be attributed to that the electromagnetic brake generated by DC electromagnetic field can suppress effectively the metal surface fluctuation generated by rotary electromagnetic field. As a result, the fine equiaxed grain fraction of ingots can be increased to 96 % and the shrinkage porosity of ingots can be greatly reduced
