Volume 44,Issue 8,2015 Table of Contents
2015, 44(8):1827-1831.
Abstract:
The deformation mechanism and microstructure evolution of TLM titanium alloy were studied during cold compression at room temperature and hot compression at 850 oC under the condition of 0.001 s-1 strain rate. The results show that the deformation mechanisms and microstructure evolution under cold and hot compressions of TLM alloy are different. Twinning, stress-induced α" phase transformations and dislocations slipping are the main deformation feature in cold compression, whereas the dislocations slipping, dynamic recovery (DR) and dynamic recrystallization (DRX) are the main deformation mechanisms in hot compression. The stress flow softening of TLM alloy in hot compression is related to DR and DRX. Meanwhile, the compressive strengths in cold and hot compression are 975 and 40 MPa, respectively. Compared with the cold compression, the compressive strength of hot compression is decreased by about 96%
The deformation mechanism and microstructure evolution of TLM titanium alloy were studied during cold compression at room temperature and hot compression at 850 oC under the condition of 0.001 s-1 strain rate. The results show that the deformation mechanisms and microstructure evolution under cold and hot compressions of TLM alloy are different. Twinning, stress-induced α" phase transformations and dislocations slipping are the main deformation feature in cold compression, whereas the dislocations slipping, dynamic recovery (DR) and dynamic recrystallization (DRX) are the main deformation mechanisms in hot compression. The stress flow softening of TLM alloy in hot compression is related to DR and DRX. Meanwhile, the compressive strengths in cold and hot compression are 975 and 40 MPa, respectively. Compared with the cold compression, the compressive strength of hot compression is decreased by about 96%
2015, 44(8):1832-1837.
Abstract:
Based on the in-situ polymerization and chemical vapor deposition method (CVD), the synthesis method of CNTs/Cu composite powder was developed by Cr/Cu catalyst via CVD. The crystal phase and micro morphologies of the as-synthesized materials were characterized using scanning electron microscopy (SEM) and Raman spectrum as well as transmission electron microscopy (TEM), respectively. The results show that the superior quality and well-crystallized CNTs/Cu composite powder can be produced by CVD using 10wt% Cr/Cu catalyst at growth temperature as low as 1073 K, for growth time of 30 min and under mixture gas of H2/C2H4 with a flow rate of 2450/300 mL/min
Based on the in-situ polymerization and chemical vapor deposition method (CVD), the synthesis method of CNTs/Cu composite powder was developed by Cr/Cu catalyst via CVD. The crystal phase and micro morphologies of the as-synthesized materials were characterized using scanning electron microscopy (SEM) and Raman spectrum as well as transmission electron microscopy (TEM), respectively. The results show that the superior quality and well-crystallized CNTs/Cu composite powder can be produced by CVD using 10wt% Cr/Cu catalyst at growth temperature as low as 1073 K, for growth time of 30 min and under mixture gas of H2/C2H4 with a flow rate of 2450/300 mL/min
2015, 44(8):1838-1844.
Abstract:
Silane treatment has good corrosion resistance to protect magnesium. In order to delay the galvanic corrosion of Mg-7Gd-5Y-Nd-Zr rare earth magnesium alloy (EW75) and Ti-6Al-4V alloy (TC4), using self corrosion magnesium alloy as the contrast group, the galvanic corrosion behavior of magnesium alloy modified with and without silane coupled with TC4 alloy were investigated. The surface morphologies of magnesium alloy after immersion in NaCl solution for 48 h were examined with digital photography and scanning electron microscopy (SEM). And the self corrosion current density and the galvanic corrosion current density of the specimens were characterized by polarization and galvanic corrosion tests, respectively. The results show that silane film can reduce the weight loss rate of Mg alloy, and transform local pitting corrosion into uniform corrosion, and the magnesium alloy with silane pretreatment has better galvanic corrosion resistance compared with as-received Mg alloy. It can be explained that silane film can improve the potential of magnesium alloy and reduce the galvanic corrosion current density
Silane treatment has good corrosion resistance to protect magnesium. In order to delay the galvanic corrosion of Mg-7Gd-5Y-Nd-Zr rare earth magnesium alloy (EW75) and Ti-6Al-4V alloy (TC4), using self corrosion magnesium alloy as the contrast group, the galvanic corrosion behavior of magnesium alloy modified with and without silane coupled with TC4 alloy were investigated. The surface morphologies of magnesium alloy after immersion in NaCl solution for 48 h were examined with digital photography and scanning electron microscopy (SEM). And the self corrosion current density and the galvanic corrosion current density of the specimens were characterized by polarization and galvanic corrosion tests, respectively. The results show that silane film can reduce the weight loss rate of Mg alloy, and transform local pitting corrosion into uniform corrosion, and the magnesium alloy with silane pretreatment has better galvanic corrosion resistance compared with as-received Mg alloy. It can be explained that silane film can improve the potential of magnesium alloy and reduce the galvanic corrosion current density
2015, 44(8):1851-1856.
Abstract:
PyC/SiC compound coating was deposited on carbon fiber preform by chemical vapor deposition (CVD) process for improving the wettability and reducing the chemical reaction between molten aluminum alloy and carbon fibers. Cf/Al composites were fabricated through the extrusion directly following vacuum pressure infiltration process. Effects of coating deposition parameters on the quality of carbon fiber coating were studied, and the influences of the coating on the infiltration quality and the mechanical properties of composites were also investigated by means of the microstructural analysis and mechanical property tests. The results show that the deposition rate of the coating is mainly controlled by the deposition temperature, and the uniform thickness of PyC/SiC compound coating can be obtained by controlling the deposition temperature or deposition time. The coating on carbon fiber preform can improve the infiltration quality and mechanical properties greatly based on the suitable interface bonding strength and good wettability. The optimized PyC/SiC compound coating thicknesses are 0.068 μm (PyC coating) and 0.257 μm (SiC coating) for better improving the composite properties
PyC/SiC compound coating was deposited on carbon fiber preform by chemical vapor deposition (CVD) process for improving the wettability and reducing the chemical reaction between molten aluminum alloy and carbon fibers. Cf/Al composites were fabricated through the extrusion directly following vacuum pressure infiltration process. Effects of coating deposition parameters on the quality of carbon fiber coating were studied, and the influences of the coating on the infiltration quality and the mechanical properties of composites were also investigated by means of the microstructural analysis and mechanical property tests. The results show that the deposition rate of the coating is mainly controlled by the deposition temperature, and the uniform thickness of PyC/SiC compound coating can be obtained by controlling the deposition temperature or deposition time. The coating on carbon fiber preform can improve the infiltration quality and mechanical properties greatly based on the suitable interface bonding strength and good wettability. The optimized PyC/SiC compound coating thicknesses are 0.068 μm (PyC coating) and 0.257 μm (SiC coating) for better improving the composite properties
2015, 44(8):1857-1861.
Abstract:
Cp/AlSn composite coatings were deposited with 0.2 A to 0.8 A carbon target current on a bearing alloy and single crystal Si (100) wafer via unbalanced magnetron sputtering. X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the phase compositions, the morphologies and the chemical states of the deposited films, respectively. Results show that the composite coating has equiaxed crystal. The phases of Cp/AlSn films consist of homogeneously mixed aluminum, tin and carbon. The XPS spectrum of the deposited Cp/AlSn films confirms that aluminum and tin exist mainly in the form of pure metals, and carbon element is composed of sp2 and sp3 bonds, among which sp2 is the main bond
Cp/AlSn composite coatings were deposited with 0.2 A to 0.8 A carbon target current on a bearing alloy and single crystal Si (100) wafer via unbalanced magnetron sputtering. X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the phase compositions, the morphologies and the chemical states of the deposited films, respectively. Results show that the composite coating has equiaxed crystal. The phases of Cp/AlSn films consist of homogeneously mixed aluminum, tin and carbon. The XPS spectrum of the deposited Cp/AlSn films confirms that aluminum and tin exist mainly in the form of pure metals, and carbon element is composed of sp2 and sp3 bonds, among which sp2 is the main bond
Zhang Xigui
,
Hua Li
,
Yang Endong
,
Chen Jingkun
,
An Zhongxun
,
Wu Mingxia
,
Huang Tingli
,
Yu Jiafei
2015, 44(8):1866-1872.
Abstract:
Amorphous hydrous ruthenium dioxide RuO2·xH2O was synthesized by a modified neutralization reaction and heat treatment process, and electrochemical performances of the synthesized product were investigated using the graphite plate with high conductivity as current collector. In the experiment a home-made sprayer and sodium dodecyle sulfate (SDS) were used as an assistant technique and dispersive agent, respectively. Results indicate that amorphous and high performance electrode materials with great specific area of 218 m2/g and fluffy and heavy black color morphology can be obtained after the precursor of the synthesized product is annealed at 175 oC. Cyclic voltammetry (CV) results show the prepared product is featured with good average specific capacitance (995 F/g at 1 mV/s) and excellent electrochemical rate. It is further proved by electrochemical impedance spectra (EIS) test that the prepared product has lower equivalent serial resistance of ~25 mΩ and good electrochemical rate performance
Amorphous hydrous ruthenium dioxide RuO2·xH2O was synthesized by a modified neutralization reaction and heat treatment process, and electrochemical performances of the synthesized product were investigated using the graphite plate with high conductivity as current collector. In the experiment a home-made sprayer and sodium dodecyle sulfate (SDS) were used as an assistant technique and dispersive agent, respectively. Results indicate that amorphous and high performance electrode materials with great specific area of 218 m2/g and fluffy and heavy black color morphology can be obtained after the precursor of the synthesized product is annealed at 175 oC. Cyclic voltammetry (CV) results show the prepared product is featured with good average specific capacitance (995 F/g at 1 mV/s) and excellent electrochemical rate. It is further proved by electrochemical impedance spectra (EIS) test that the prepared product has lower equivalent serial resistance of ~25 mΩ and good electrochemical rate performance
2015, 44(8):1873-1878.
Abstract:
The microstructure evolution and the tensile properties of the second generation single crystal superalloy DD6 were investigated after full heat treatment and aging process at 980~1200 oC. The results indicate that the morphological instability occurs at relatively high temperature, and the γ′ phase gradually connects and rafts after aged for 800 h at 1050 oC. After aged for 100 h at 1200 oC, the γ/γ′ microstructure cubicity gradually becomes weaker and transforms into spherical boundary, accompanied with a few finer matrix phase embedded into strengthening phases. Whereas the dislocation lines are homogeneously distributed in the γ/γ′ interface area, and dislocation motions are also strengthened with increasing of aging time and temperature. After aged at 1050 oC for 1000 h, the precipitation phase in the form of blocky appears in the enrichment areas of solution strengthening elements and its brittle characteristics will pile up dislocation motions at lower temperature. The ultimate tensile strength, yield strength and elongation percentage decrease with increasing of aging time, while a fluctuation of contraction area will occur at 760 oC
The microstructure evolution and the tensile properties of the second generation single crystal superalloy DD6 were investigated after full heat treatment and aging process at 980~1200 oC. The results indicate that the morphological instability occurs at relatively high temperature, and the γ′ phase gradually connects and rafts after aged for 800 h at 1050 oC. After aged for 100 h at 1200 oC, the γ/γ′ microstructure cubicity gradually becomes weaker and transforms into spherical boundary, accompanied with a few finer matrix phase embedded into strengthening phases. Whereas the dislocation lines are homogeneously distributed in the γ/γ′ interface area, and dislocation motions are also strengthened with increasing of aging time and temperature. After aged at 1050 oC for 1000 h, the precipitation phase in the form of blocky appears in the enrichment areas of solution strengthening elements and its brittle characteristics will pile up dislocation motions at lower temperature. The ultimate tensile strength, yield strength and elongation percentage decrease with increasing of aging time, while a fluctuation of contraction area will occur at 760 oC
2015, 44(8):1879-1882.
Abstract:
After dropping Eu(NO3)3 into pseudoboehmite sol solution, europium-added pseudoboehmite xerogel was prepared by spray-drying process. Effect of Eu3 ion on pseudoboehmite phase transition and microstructure has investigated by differential thermal gravimetric analysis, powder X-ray diffraction and field emission transmission electron microscopy. The results show that phase transition temperatures of γ-Al2O3→θ-Al2O3 and θ-Al2O3→α-Al2O3 in the Eu3 -doped pseudoboehmite phase transition process are increased by 172 K and 13 K, respectively. Eu3 ions entered entirely into γ-Al2O3 or θ-Al2O3 crystal lattices, and crystallinity of γ-Al2O3 was improved, thus increasing the phase transition temperature of γ-Al2O3→θ-Al2O3. When α-Al2O3 formed in the phase transition process, Eu3 ion, which presented wholly in the form of compound EuA112O19, existed between α- Al2O3 grains. Bulk diffusion of Al3 was hindered, resulting in an increase of phase transformation temperature of θ-Al2O3→α-Al2O3 process.
After dropping Eu(NO3)3 into pseudoboehmite sol solution, europium-added pseudoboehmite xerogel was prepared by spray-drying process. Effect of Eu3 ion on pseudoboehmite phase transition and microstructure has investigated by differential thermal gravimetric analysis, powder X-ray diffraction and field emission transmission electron microscopy. The results show that phase transition temperatures of γ-Al2O3→θ-Al2O3 and θ-Al2O3→α-Al2O3 in the Eu3 -doped pseudoboehmite phase transition process are increased by 172 K and 13 K, respectively. Eu3 ions entered entirely into γ-Al2O3 or θ-Al2O3 crystal lattices, and crystallinity of γ-Al2O3 was improved, thus increasing the phase transition temperature of γ-Al2O3→θ-Al2O3. When α-Al2O3 formed in the phase transition process, Eu3 ion, which presented wholly in the form of compound EuA112O19, existed between α- Al2O3 grains. Bulk diffusion of Al3 was hindered, resulting in an increase of phase transformation temperature of θ-Al2O3→α-Al2O3 process.
2015, 44(8):1883-1887.
Abstract:
A constitutive model using dislocation density rate as an internal state variable has been proposed for hot working of near β titanium alloy in this paper. In the constitutive equations, the effects of solution strengthening and dislocation interaction on flow stress were included. Based on the internal-state-variable based model, the constitutive relationship of a new near β titanium alloy Ti-7Mo-3Al-3Nb-3Cr (Ti-7333) for high temperature deformation was established. And the model parameters were obtained by the genetic algorithm based objective optimization method. Calculating results show that the average relative difference between the calculated and the experimental ?ow stress is about 7.2%. Note that the developed internal-state-variable based constitutive model can efficiently characterize the flow behavior of Ti-7333 alloy.
A constitutive model using dislocation density rate as an internal state variable has been proposed for hot working of near β titanium alloy in this paper. In the constitutive equations, the effects of solution strengthening and dislocation interaction on flow stress were included. Based on the internal-state-variable based model, the constitutive relationship of a new near β titanium alloy Ti-7Mo-3Al-3Nb-3Cr (Ti-7333) for high temperature deformation was established. And the model parameters were obtained by the genetic algorithm based objective optimization method. Calculating results show that the average relative difference between the calculated and the experimental ?ow stress is about 7.2%. Note that the developed internal-state-variable based constitutive model can efficiently characterize the flow behavior of Ti-7333 alloy.
10 Optical and Photocatalytic Properties of Cu-Cu2O/TiO2 Two-Layer Nanocomposite Films on Si Substrates
2015, 44(8):1888-1893.
Abstract:
This paper introduced a process to prepare novel Cu-Cu2O/TiO2 two-layer nanocomposite films with Cu-Cu2O mixture layers grown on TiO2 films prepared by a magnetron sputtering method. The structure, the morphology and optical properties of the films were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), fluorescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectroscopy (DRS). XRD patterns indicate that the Cu-Cu2O mixture layer does not change the crystalline phase of TiO2. XPS results show that the presence of Cu restrains the oxidation of Cu2O surface for Cu-Cu2O/TiO2 layer. SEM analysis reveals that the well crystallized Cu-Cu2O mixture nanoparticles are dispersed uniformly on the surface of TiO2. Owing to UV-vis diffuse reflectance spectroscopy, an red shift of the extended absorption edge of Cu-Cu2O/TiO2 takes place. PL spectra confirm the presence of Cu which reduces the recombination rate of exited electron-hole. Photocatalytic experiments demonstrate that compared with pure Cu2O/TiO2, the as-prepared Cu-Cu2O/TiO2-8 shows greater efficiency in photogenerated carriers and a significantly improved photocatalytic performance. In addition the reason for improvement in photocatalytic activity of the Cu-Cu2O/TiO2-8 films was also discussed
This paper introduced a process to prepare novel Cu-Cu2O/TiO2 two-layer nanocomposite films with Cu-Cu2O mixture layers grown on TiO2 films prepared by a magnetron sputtering method. The structure, the morphology and optical properties of the films were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), fluorescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectroscopy (DRS). XRD patterns indicate that the Cu-Cu2O mixture layer does not change the crystalline phase of TiO2. XPS results show that the presence of Cu restrains the oxidation of Cu2O surface for Cu-Cu2O/TiO2 layer. SEM analysis reveals that the well crystallized Cu-Cu2O mixture nanoparticles are dispersed uniformly on the surface of TiO2. Owing to UV-vis diffuse reflectance spectroscopy, an red shift of the extended absorption edge of Cu-Cu2O/TiO2 takes place. PL spectra confirm the presence of Cu which reduces the recombination rate of exited electron-hole. Photocatalytic experiments demonstrate that compared with pure Cu2O/TiO2, the as-prepared Cu-Cu2O/TiO2-8 shows greater efficiency in photogenerated carriers and a significantly improved photocatalytic performance. In addition the reason for improvement in photocatalytic activity of the Cu-Cu2O/TiO2-8 films was also discussed
2015, 44(8):1894-1898.
Abstract:
The process of extraction vanadium from LD converter slag by pressure leaching with titanium white waste acid was investigated. The mineralogy analysis indicates that several kinds of spinel containing Fe, V, Ti, Mn and Cr, mainly exist in the converter slag. Potential-pH diagrams of V-Fe-H2O, V-Ti-H2O, V-Mn-H2O, V-Cr-H2O system have been calculated at elevated temperature condition (150 oC). The thermodynamics diagrams show that soluble ions of V and Fe2+, Fe3+, Mn2+, Cr2+ and Cr3+ can be extracted by the acidic leachate during the pressure leaching process. The results of orthogonal experiment reveal that the impacts of temperature and initial acid concentration on the vanadium extraction process are effective. The effect of temperature on the leaching process was further investigated with a increased temperature from 100 oC to 160 oC, and the results indicate that the content of titanium in the residue is 4.56% to about 12.0%, while other elements tend to be enriched in the leaching solution. Under the optimization condition (temperature 140 oC, liquid-solid ratio 10:1, concentration of acid at 200 g·L-1, stirring speed 500 r/min and the reaction time of 90 min), the leaching rate of vanadium is 96.85%
The process of extraction vanadium from LD converter slag by pressure leaching with titanium white waste acid was investigated. The mineralogy analysis indicates that several kinds of spinel containing Fe, V, Ti, Mn and Cr, mainly exist in the converter slag. Potential-pH diagrams of V-Fe-H2O, V-Ti-H2O, V-Mn-H2O, V-Cr-H2O system have been calculated at elevated temperature condition (150 oC). The thermodynamics diagrams show that soluble ions of V and Fe2+, Fe3+, Mn2+, Cr2+ and Cr3+ can be extracted by the acidic leachate during the pressure leaching process. The results of orthogonal experiment reveal that the impacts of temperature and initial acid concentration on the vanadium extraction process are effective. The effect of temperature on the leaching process was further investigated with a increased temperature from 100 oC to 160 oC, and the results indicate that the content of titanium in the residue is 4.56% to about 12.0%, while other elements tend to be enriched in the leaching solution. Under the optimization condition (temperature 140 oC, liquid-solid ratio 10:1, concentration of acid at 200 g·L-1, stirring speed 500 r/min and the reaction time of 90 min), the leaching rate of vanadium is 96.85%
2015, 44(8):1904-1908.
Abstract:
The friction and wear experiment has been done in the crystal surface of Ge(100), Ge(110) and Ge(111) in nanoscale by nano-indenter and Atomic force Microscope. Under heavy load conditions, the grooves appear in all of the friction of three different single plane orientations, and the debris accumulate obviously on the verge of nick. As shown in the friction experiment, the effect of crystal orientation is slight on the friction performance of single crystal germanium. The friction force of single crystal germanium increases along with the increment of sliding velocity. Whereas, with the increment of sliding velocity, severe friction trench damage occurs in the crystal surface, the volume of accumulated debris on the verge of nick and the depth of groove become bigger. Under low load conditions, the friction is stable basically. But with the increment of load, the friction of crystal germanium is of nonlinear growth, and there is a brittle plastic transition from plastic deformation to brittle failure on the crystal surface, causing the brittle stripping of the surface of single crystal germanium and the debris accumulation on the two sides of the groove when the load increases to a certain value
The friction and wear experiment has been done in the crystal surface of Ge(100), Ge(110) and Ge(111) in nanoscale by nano-indenter and Atomic force Microscope. Under heavy load conditions, the grooves appear in all of the friction of three different single plane orientations, and the debris accumulate obviously on the verge of nick. As shown in the friction experiment, the effect of crystal orientation is slight on the friction performance of single crystal germanium. The friction force of single crystal germanium increases along with the increment of sliding velocity. Whereas, with the increment of sliding velocity, severe friction trench damage occurs in the crystal surface, the volume of accumulated debris on the verge of nick and the depth of groove become bigger. Under low load conditions, the friction is stable basically. But with the increment of load, the friction of crystal germanium is of nonlinear growth, and there is a brittle plastic transition from plastic deformation to brittle failure on the crystal surface, causing the brittle stripping of the surface of single crystal germanium and the debris accumulation on the two sides of the groove when the load increases to a certain value
13 Corrosion Resistance Behavior to Sulfate of Multi-elements Alloy CoCrFeNiTi0.5 at High Temperature
2015, 44(8):1919-1923.
Abstract:
Multi-elements alloy with good thermal stability is expected to serve as the superheater tube material of ultra-supercritical boiler and may suffer from hot corrosion under the coal-fired atmosphere. In this study, the corrosion resistance behavior of multi-elements alloy CoCrFeNiTi0.5 coated with alkali metal sulfate at 750 °C was investigated. The results show the corrosion kinetics curves of the alloy follow parabolic growth rate and the corrosion products, which consist of volatile Na4(CrO4)(SO4), (Fe, Ni) sulfide, Cr/Ti oxide as well as compound oxides with spinel structure, form on the surface and sub-surface of the alloy. The oxide layer is dense and has good adhesion with the matrix at the beginning of corrosion. With the corrosion time increasing, the oxide layer in thickness increases and becomes loose as well as porous. The micro-pores are generated in the interface between the oxide scale and matrix with the formation of the internal oxidation and internal sulfidation. In a word，the corrosion resistance behavior of multi-elements alloy CoCrFeNiTi0.5 at 750 °C can be attributed to the formation of the protective oxide layers and to the basic fluxing in molten Na2SO4 induced by low melting point eutectic.
Multi-elements alloy with good thermal stability is expected to serve as the superheater tube material of ultra-supercritical boiler and may suffer from hot corrosion under the coal-fired atmosphere. In this study, the corrosion resistance behavior of multi-elements alloy CoCrFeNiTi0.5 coated with alkali metal sulfate at 750 °C was investigated. The results show the corrosion kinetics curves of the alloy follow parabolic growth rate and the corrosion products, which consist of volatile Na4(CrO4)(SO4), (Fe, Ni) sulfide, Cr/Ti oxide as well as compound oxides with spinel structure, form on the surface and sub-surface of the alloy. The oxide layer is dense and has good adhesion with the matrix at the beginning of corrosion. With the corrosion time increasing, the oxide layer in thickness increases and becomes loose as well as porous. The micro-pores are generated in the interface between the oxide scale and matrix with the formation of the internal oxidation and internal sulfidation. In a word，the corrosion resistance behavior of multi-elements alloy CoCrFeNiTi0.5 at 750 °C can be attributed to the formation of the protective oxide layers and to the basic fluxing in molten Na2SO4 induced by low melting point eutectic.
2015, 44(8):1924-1927.
Abstract:
Using the technology of split Hopkinson bar, dynamic mechanical experiments under high strain-rate loading on hat-shape samples of TC6 titanium alloy with binary structure have been conducted and the fracture failure mechanism has been investigated. It is shown that the fracture of TC6 titanium alloy with binary structure is often related to adiabatic shear band when deformed at the high strain rate. Its fracture includes three stages, i.e. nucleation of voids, growth of voids to form micro-crack and expansion of the micro-crack to form fracture
Using the technology of split Hopkinson bar, dynamic mechanical experiments under high strain-rate loading on hat-shape samples of TC6 titanium alloy with binary structure have been conducted and the fracture failure mechanism has been investigated. It is shown that the fracture of TC6 titanium alloy with binary structure is often related to adiabatic shear band when deformed at the high strain rate. Its fracture includes three stages, i.e. nucleation of voids, growth of voids to form micro-crack and expansion of the micro-crack to form fracture
2015, 44(8):1948-1952.
Abstract:
The effects of current pulse width on Micro-arc Oxidation (MAO) process for AZ31B magnesium alloys were investigated using pulse power source. The pulse shapes were recorded by an oscillograph. The thickness of MAO coat was measured by an eddy current thickness gauge. The surface and cross section morphologies of MAO coat were observed by scanning electron microscope (SEM). The energy consumption of MAO process was calculated by curves of voltage-time. The results indicate that with current pulse width increasing from 15 μs to 90 μs, the arcing time during MAO process shortens from 358 s to 25 s, the arcing voltage first drops and then increases. When pulse width is 30 μs, the arcing voltage reaches the minimum value of 183 V. The pore diameter of Millipore is enlarged but the quantity is reduced. And the thicker ceramic coat is obtained on Mg samples but the density of MAO coat is decreased. The energy consumption of arcing process is decreased at first and then raised with increasing of pulse width, and the minimum value is 3.9 kJ when pulse width is 30 μs. The energy consumption of MAO coat growing process is nearly of fold increase with increasing of pulse current. The energy consumption per thickness of MAO coat drops firstly and then rises stably, and the minimum value is 10.2 kJ when pulse width is 30 μs.
The effects of current pulse width on Micro-arc Oxidation (MAO) process for AZ31B magnesium alloys were investigated using pulse power source. The pulse shapes were recorded by an oscillograph. The thickness of MAO coat was measured by an eddy current thickness gauge. The surface and cross section morphologies of MAO coat were observed by scanning electron microscope (SEM). The energy consumption of MAO process was calculated by curves of voltage-time. The results indicate that with current pulse width increasing from 15 μs to 90 μs, the arcing time during MAO process shortens from 358 s to 25 s, the arcing voltage first drops and then increases. When pulse width is 30 μs, the arcing voltage reaches the minimum value of 183 V. The pore diameter of Millipore is enlarged but the quantity is reduced. And the thicker ceramic coat is obtained on Mg samples but the density of MAO coat is decreased. The energy consumption of arcing process is decreased at first and then raised with increasing of pulse width, and the minimum value is 3.9 kJ when pulse width is 30 μs. The energy consumption of MAO coat growing process is nearly of fold increase with increasing of pulse current. The energy consumption per thickness of MAO coat drops firstly and then rises stably, and the minimum value is 10.2 kJ when pulse width is 30 μs.
2015, 44(8):1953-1958.
Abstract:
Isothermal oxidation kinetics and oxidation mechanism of GH3535 superalloy was studied at 700 °C for 700 h. The morphology and component of the high-temperature oxide scale for GH3535 alloy was analyzed by SEM, XRD, EPMA and SRXRF techniques. The results show that the oxidation kinetics curve of GH3535 alloy follows the cubic law at 700 °C. Thickness of the oxidation film is about 5 μm and internal oxidation does not occur. The oxidation film has no obvious spallation and it is composed of NiO, Cr2O3, NiCr2O4 and NiMn2O4
Isothermal oxidation kinetics and oxidation mechanism of GH3535 superalloy was studied at 700 °C for 700 h. The morphology and component of the high-temperature oxide scale for GH3535 alloy was analyzed by SEM, XRD, EPMA and SRXRF techniques. The results show that the oxidation kinetics curve of GH3535 alloy follows the cubic law at 700 °C. Thickness of the oxidation film is about 5 μm and internal oxidation does not occur. The oxidation film has no obvious spallation and it is composed of NiO, Cr2O3, NiCr2O4 and NiMn2O4
2015, 44(8):1959-1963.
Abstract:
An in situ nanoindentation test system was established by combining atomic force microscope (AFM) and scan electron microscope (SEM). This system enabled the indentation experiment using the AFM cantilever with Cube corner diamond indenter, and acquired the curve of load versus displacement. The experimental process can be observed in real time by in situ SEM simultaneously. A mechanical property testing method, based on the AFM cantilever loading curve and the in situ SEM indentation of images analysis, was well developed. The hardness and elastic model of the plastic thin film were obtained by measuring the maximum loading during the indentation and the residual area of the indentation by measuring SEM image. This method was demonstrated by conducting the indentation experiment on the sliver film deposited on the Si substrate using magnetron sputtering. Furthermore, the experiment conducted by the Nanoindenter G200 was presented here for comparison. The results show that the in situ AFM indentation possesses higher resolution of loading and displacement, and can achieve the indentation experiment scaled from nN to mN of the applied load. The hardness of the plastic thin film can be obtained by measuring the residual area of indentation. The pile-up effect of the soft film deposited on the hard substrate, which exists in the Oliver-pharr method, can be reduced by SEM image analyses of residual area and the calculation has a higher testing?accuracy?and?reliability as well
An in situ nanoindentation test system was established by combining atomic force microscope (AFM) and scan electron microscope (SEM). This system enabled the indentation experiment using the AFM cantilever with Cube corner diamond indenter, and acquired the curve of load versus displacement. The experimental process can be observed in real time by in situ SEM simultaneously. A mechanical property testing method, based on the AFM cantilever loading curve and the in situ SEM indentation of images analysis, was well developed. The hardness and elastic model of the plastic thin film were obtained by measuring the maximum loading during the indentation and the residual area of the indentation by measuring SEM image. This method was demonstrated by conducting the indentation experiment on the sliver film deposited on the Si substrate using magnetron sputtering. Furthermore, the experiment conducted by the Nanoindenter G200 was presented here for comparison. The results show that the in situ AFM indentation possesses higher resolution of loading and displacement, and can achieve the indentation experiment scaled from nN to mN of the applied load. The hardness of the plastic thin film can be obtained by measuring the residual area of indentation. The pile-up effect of the soft film deposited on the hard substrate, which exists in the Oliver-pharr method, can be reduced by SEM image analyses of residual area and the calculation has a higher testing?accuracy?and?reliability as well
2015, 44(8):1970-1974.
Abstract:
Passivation coatings were prepared on tin-plating steel by an electrochemical method. The corrosion resistance of the coatings was tested by CuSO4 drip experiment, electrochemical impedance spectroscopy, Tafel and SEM. Effects of current density, additives and passivation time on the properties of the passivation coatings were studied. It is concluded that the corrosion resistance of passivation films increases first and then becomes steady with the increasing of passivation time. When the passivation time is 40 s, the corrosion resistance of the coating is the best. The technological parameters of the passivation solution are obtained by experiment as following: sodium molybdate 25 g·L–1, phytic acid 6.5 g·L–1, pH=4.5, time 40 s and Jk=1.5 mA·cm-2. The apparent morphologies of the coating are well-proportioned covered on the surface of tin coatings. The results show that the corrosion potential of the tin layer is increased by 0.108 V, the corrosion current decreased by 2.3577×10-5 A·cm-2, and the drip time increased by 23.3 s. The passivation effect of the coatings prepared by the electrochemical method is nearly to that of chromating, and it increases the corrosion resistance of the tin coating effectively
Passivation coatings were prepared on tin-plating steel by an electrochemical method. The corrosion resistance of the coatings was tested by CuSO4 drip experiment, electrochemical impedance spectroscopy, Tafel and SEM. Effects of current density, additives and passivation time on the properties of the passivation coatings were studied. It is concluded that the corrosion resistance of passivation films increases first and then becomes steady with the increasing of passivation time. When the passivation time is 40 s, the corrosion resistance of the coating is the best. The technological parameters of the passivation solution are obtained by experiment as following: sodium molybdate 25 g·L–1, phytic acid 6.5 g·L–1, pH=4.5, time 40 s and Jk=1.5 mA·cm-2. The apparent morphologies of the coating are well-proportioned covered on the surface of tin coatings. The results show that the corrosion potential of the tin layer is increased by 0.108 V, the corrosion current decreased by 2.3577×10-5 A·cm-2, and the drip time increased by 23.3 s. The passivation effect of the coatings prepared by the electrochemical method is nearly to that of chromating, and it increases the corrosion resistance of the tin coating effectively
2015, 44(8):1979-1984.
Abstract:
Borosiliconizing of 99.9% pure nickel was performed by a powder-pack method using borosiliconizing powders at 850, 900 and 950 °C for 2 and 8 h. The coated samples were characterized by Optical Microscope (OM), X-ray diffraction (XRD) and hardness tests. The oxidation behavior of unborosiliconized and borosiliconized pure nickel was studied with the kinetics curves of cyclic oxidation. The results show that boride (Ni2B) and silicide phases (Ni3Si, Ni5Si2 and Ni2Si) are formed on the surface of borosiliconized pure nickel, which are confirmed by X-ray diffraction analysis. Depending on boronizing time and temperature, the thickness of coating layer ranges from 36 to 237 mm. The hardness of the coating layer is much higher than that of pure nickel. Dry-sliding wear tests show that the wear resistance of borosiliconized pure nickel is greater than that of pure nickel. However, the oxidation test at 950 °C indicates that unborosiliconized sample possesses higher oxidation resistance than the borosiliconized sample.
Borosiliconizing of 99.9% pure nickel was performed by a powder-pack method using borosiliconizing powders at 850, 900 and 950 °C for 2 and 8 h. The coated samples were characterized by Optical Microscope (OM), X-ray diffraction (XRD) and hardness tests. The oxidation behavior of unborosiliconized and borosiliconized pure nickel was studied with the kinetics curves of cyclic oxidation. The results show that boride (Ni2B) and silicide phases (Ni3Si, Ni5Si2 and Ni2Si) are formed on the surface of borosiliconized pure nickel, which are confirmed by X-ray diffraction analysis. Depending on boronizing time and temperature, the thickness of coating layer ranges from 36 to 237 mm. The hardness of the coating layer is much higher than that of pure nickel. Dry-sliding wear tests show that the wear resistance of borosiliconized pure nickel is greater than that of pure nickel. However, the oxidation test at 950 °C indicates that unborosiliconized sample possesses higher oxidation resistance than the borosiliconized sample.
2015, 44(8):1994-1998.
Abstract:
Centrifugal separation process was used to filtrate germanium dioxide hydrolyzed from germanium tetrachloride, and the effects of different parameters on direct?recovery rate, moisture content and chlorine content in filter cake were analyzed. The following optimized processing parameters are obtained: centrifuge filter cloth aperture 2.6 mm, the dehydration speed 1200 r/min, the filter cake thickness 80~100 mm, the single washing lotion amount 20 L, and the washing water cycle 3~5 times. The results show that the direct recovery rate of germanium dioxide can reach 99.62%, the moisture content is less than 8%, and the chlorine content is less than 0.05% in the filter cake. These samples after drying again can meet the international standard of?GeO2-06
Centrifugal separation process was used to filtrate germanium dioxide hydrolyzed from germanium tetrachloride, and the effects of different parameters on direct?recovery rate, moisture content and chlorine content in filter cake were analyzed. The following optimized processing parameters are obtained: centrifuge filter cloth aperture 2.6 mm, the dehydration speed 1200 r/min, the filter cake thickness 80~100 mm, the single washing lotion amount 20 L, and the washing water cycle 3~5 times. The results show that the direct recovery rate of germanium dioxide can reach 99.62%, the moisture content is less than 8%, and the chlorine content is less than 0.05% in the filter cake. These samples after drying again can meet the international standard of?GeO2-06
Sun Kai
,
Wang Dawei
,
Wang Meili
,
Liu Mengqi
,
Feng Jing
,
Li Zhongxiang
,
Zhao Quanliang
,
Cui Yan
2015, 44(8):1999-2002.
Abstract:
The Bismuth ferrite (BiFeO3) powders were hydrothermally synthesized using Fe(NO3)3·9H2O and Bi(NO3)3·5H2O as starting materials, and NaOH as a mineralizer. Phase structure and micro-morphology of BiFeO3 powders under various reaction conditions were investigated. Results show that only impurity phase is observed at low reaction temperature. With increasing reaction temperature, the impurity phase is reduced and the BiFeO3 phase is significantly increased. The extension of reaction time could reduce impurity phase, and pure BiFeO3 is achieved with low mineralizer concentration of 1 mol/L calcined at 170 °C for 24 h. Furthermore, the products with different morphologies are obtained by adjusting reaction condition, such as slices, spheroids, nano-particles, nano-wires, tetrahedrons. It is found that large-scale spheroids (~10 μm) could be obtained with moderate reaction temperature, time and mineralizer concentration, and the increase of reaction time promotes the growth of one-dimension nano-structures and nano-particles
The Bismuth ferrite (BiFeO3) powders were hydrothermally synthesized using Fe(NO3)3·9H2O and Bi(NO3)3·5H2O as starting materials, and NaOH as a mineralizer. Phase structure and micro-morphology of BiFeO3 powders under various reaction conditions were investigated. Results show that only impurity phase is observed at low reaction temperature. With increasing reaction temperature, the impurity phase is reduced and the BiFeO3 phase is significantly increased. The extension of reaction time could reduce impurity phase, and pure BiFeO3 is achieved with low mineralizer concentration of 1 mol/L calcined at 170 °C for 24 h. Furthermore, the products with different morphologies are obtained by adjusting reaction condition, such as slices, spheroids, nano-particles, nano-wires, tetrahedrons. It is found that large-scale spheroids (~10 μm) could be obtained with moderate reaction temperature, time and mineralizer concentration, and the increase of reaction time promotes the growth of one-dimension nano-structures and nano-particles
2015, 44(8):2003-2006.
Abstract:
The effect of multi-axial compression on microstructure and mechanical properties of 7085 aluminum alloy extrusions was investigated by X-ray diffraction (XRD), electron back-scattered diffraction (EBSD) and tensile test. The results show that multi-axial compression could refine the grain size (from 87.7 μm to 17.9 μm) with the grain refinement mechanism of dynamic recrystallization, increase the tensile strength by 110 MPa which is primarily attributed to solution strengthening and aging strengthening
The effect of multi-axial compression on microstructure and mechanical properties of 7085 aluminum alloy extrusions was investigated by X-ray diffraction (XRD), electron back-scattered diffraction (EBSD) and tensile test. The results show that multi-axial compression could refine the grain size (from 87.7 μm to 17.9 μm) with the grain refinement mechanism of dynamic recrystallization, increase the tensile strength by 110 MPa which is primarily attributed to solution strengthening and aging strengthening
2015, 44(8):2011-2014.
Abstract:
In order to improve the machinability and electrical performance of Ag/SnO2 electrical contact materials, a new kind of nano-Ag/SnO2/CeO2 electrical contact materials was designed with Ag as the matrix, SnO2 as the wild phase, and CeO2 as the additive. First, nano-SnO2/CeO2 composite powders were prepared by a liquid phase in-situ chemical route. The influence of rare earth oxide CeO2 on the microstructure and the phase composition of SnO2/CeO2 were analyzed by microstructure analysis methods. Then, the new nano-Ag/SnO2/CeO2 contact materials were prepared by powder metallurgy technology. The physical and mechanical properties, temperature rise, connecting and breaking capability of the contact terminal were tested. The results show that the electrical performances of Ag/SnO2/CeO2 materials are superior to those of the existing Ag/SnO2 materials
In order to improve the machinability and electrical performance of Ag/SnO2 electrical contact materials, a new kind of nano-Ag/SnO2/CeO2 electrical contact materials was designed with Ag as the matrix, SnO2 as the wild phase, and CeO2 as the additive. First, nano-SnO2/CeO2 composite powders were prepared by a liquid phase in-situ chemical route. The influence of rare earth oxide CeO2 on the microstructure and the phase composition of SnO2/CeO2 were analyzed by microstructure analysis methods. Then, the new nano-Ag/SnO2/CeO2 contact materials were prepared by powder metallurgy technology. The physical and mechanical properties, temperature rise, connecting and breaking capability of the contact terminal were tested. The results show that the electrical performances of Ag/SnO2/CeO2 materials are superior to those of the existing Ag/SnO2 materials
2015, 44(8):2015-2019.
Abstract:
The microstructures and work-hardening behaviors of as-extruded and as-aged ZMT614-xY (x=0, 0.1, 0.5, 1.0) alloys were investigated by optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and tensile test. The average grain size of as-extruded and as-aged ZMT614-xY (x=0, 0.1, 0.5, 1.0) alloys is decreased with more Y additive. A new irregular blocky MgSnY phase is formed when the content of Y reaches 1wt%. The work-hardening rate (θ) and work-hardening exponent (n) were obtained from the true stress-strain curves of as-extruded and as-aged samples. Due to the refined grains, the work-hardening rate θ of as-extruded and as-aged ZMT614-xY (x=0, 0.1, 0.5, 1.0) alloys are decreased with the content of Y increasing. Dynamic recovery of dislocations occurs during the plastic deformation, and the work-hardening rate θ of as-extruded and as-aged samples decreases as the deformation increases
The microstructures and work-hardening behaviors of as-extruded and as-aged ZMT614-xY (x=0, 0.1, 0.5, 1.0) alloys were investigated by optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and tensile test. The average grain size of as-extruded and as-aged ZMT614-xY (x=0, 0.1, 0.5, 1.0) alloys is decreased with more Y additive. A new irregular blocky MgSnY phase is formed when the content of Y reaches 1wt%. The work-hardening rate (θ) and work-hardening exponent (n) were obtained from the true stress-strain curves of as-extruded and as-aged samples. Due to the refined grains, the work-hardening rate θ of as-extruded and as-aged ZMT614-xY (x=0, 0.1, 0.5, 1.0) alloys are decreased with the content of Y increasing. Dynamic recovery of dislocations occurs during the plastic deformation, and the work-hardening rate θ of as-extruded and as-aged samples decreases as the deformation increases
2015, 44(8):2024-2028.
Abstract:
The effect of aging temperature on the microstructure and tensile properties of 2198 Al-Li alloy were investigated by tensile test and TEM. The results show a great dependence of tensile properties on aging temperature in a narrow temperature region before peak aging. When the temperature (150 °C~170 °C /14 h) increases, the tensile strength rises dramatically; meanwhile the tensile elongation decreases. The main precipitates detected in 2198 alloy are δ′, θ′, β′/δ′, T-1 and σ phase. The combination and morphology of precipitates vary with different aging temperatures; the main precipitates are δ′, θ′, β′/δ′ when aging below 160 °C, while above 160 °C, T-1 and σ phases come out in large numbers, and become the dominating strengthening phases gradually. It is concluded that the sensitivity of 2198 Al-Li alloy to aging temperature is essentially attributed to the variety and amount of precipitates
The effect of aging temperature on the microstructure and tensile properties of 2198 Al-Li alloy were investigated by tensile test and TEM. The results show a great dependence of tensile properties on aging temperature in a narrow temperature region before peak aging. When the temperature (150 °C~170 °C /14 h) increases, the tensile strength rises dramatically; meanwhile the tensile elongation decreases. The main precipitates detected in 2198 alloy are δ′, θ′, β′/δ′, T-1 and σ phase. The combination and morphology of precipitates vary with different aging temperatures; the main precipitates are δ′, θ′, β′/δ′ when aging below 160 °C, while above 160 °C, T-1 and σ phases come out in large numbers, and become the dominating strengthening phases gradually. It is concluded that the sensitivity of 2198 Al-Li alloy to aging temperature is essentially attributed to the variety and amount of precipitates
2015, 44(8):2029-2033.
Abstract:
Based on the empirical electron theory of solids and molecules (EET), the statistical values of valence electron structure parameters of Al-5Zr master alloy melt were calculated, and the crystallization process models of the Al3Zr phase in the Al-5Zr melt were built at high and low pouring temperatures. The effect of pouring temperature on the morphology, size and the amount of primary Al3Zr phase during the solidification of Al-5Zr master alloys was investigated. The results show that the morphologies change from small blocks to long needles, the average size increases and the amount decreases for the Al3Zr crystals with the increase of pouring temperature. When the pouring temperature is below 1000 °C, the Al-Zr and Zr-Zr clusters with larger quantities and larger gather, nucleate and finally form a large number of small blocky Al3Zr crystals; when the pouring temperature is above 1000 °C, the Zr-Zr clusters with fewer quantities and largeraggregate, nucleate and ultimately form a small number of Al3Zr crystals with long needle shape. The established models agree well with the experimental results
Based on the empirical electron theory of solids and molecules (EET), the statistical values of valence electron structure parameters of Al-5Zr master alloy melt were calculated, and the crystallization process models of the Al3Zr phase in the Al-5Zr melt were built at high and low pouring temperatures. The effect of pouring temperature on the morphology, size and the amount of primary Al3Zr phase during the solidification of Al-5Zr master alloys was investigated. The results show that the morphologies change from small blocks to long needles, the average size increases and the amount decreases for the Al3Zr crystals with the increase of pouring temperature. When the pouring temperature is below 1000 °C, the Al-Zr and Zr-Zr clusters with larger quantities and larger gather, nucleate and finally form a large number of small blocky Al3Zr crystals; when the pouring temperature is above 1000 °C, the Zr-Zr clusters with fewer quantities and largeraggregate, nucleate and ultimately form a small number of Al3Zr crystals with long needle shape. The established models agree well with the experimental results
2015, 44(8):2048-2052.
Abstract:
A steady-state thermal analysis for cooling rolls in planar-flow melt spinning (PFMS) was carried out using finite element analysis. The effects of the roll diameter, the roll thickness and the roll casting speed on the temperature of cooling roll were investigated. Results show that the temperature of the cooling roll can be decreased by increasing the roll diameter, decreasing the roll thickness and reducing the roll casting speed. Based on the orthogonal process analysis, the roll thickness is the main influence factor of outside surface temperature of the roll, followed by the casting speed and the roll diameter. The roll casting speed has the most obvious influence on inside surface temperature of the roll while the effects of the roll diameter and the roll thickness are less remarkable. Finally by considering various important indexes including mechanical strength, control stability as well as thermal requirements, the parameter optimization design to keep the surface temperature of the cooling roll in the specific range was obtained.
A steady-state thermal analysis for cooling rolls in planar-flow melt spinning (PFMS) was carried out using finite element analysis. The effects of the roll diameter, the roll thickness and the roll casting speed on the temperature of cooling roll were investigated. Results show that the temperature of the cooling roll can be decreased by increasing the roll diameter, decreasing the roll thickness and reducing the roll casting speed. Based on the orthogonal process analysis, the roll thickness is the main influence factor of outside surface temperature of the roll, followed by the casting speed and the roll diameter. The roll casting speed has the most obvious influence on inside surface temperature of the roll while the effects of the roll diameter and the roll thickness are less remarkable. Finally by considering various important indexes including mechanical strength, control stability as well as thermal requirements, the parameter optimization design to keep the surface temperature of the cooling roll in the specific range was obtained.
2015, 44(8):2053-2057.
Abstract:
Ti nanorod arrays with controllable density on titanium surfaces were prepared by tuning the content of oxalic acid. The field emission scanning electron microscopy (FE-SEM) and atomic force microscope (AFM) were used to analyze the topography and density of titanium nanorod arrays. Bioactivity was investigated by immersing the samples in a simulated body fluid (2SBF) for 3 and 5 d. Results demonstrate that the different densities of nanorod arrays result from the change of the concentration of H+. The approach herein can be developed to be a facile nanotechnology for nano-functionalization of titanium. The structure of titanium nanorod arrays promotes the growth of calcium phosphate on the surface of the titanium, the mineralization ability is the best at density of (1.79 ± 0.04)×1010/cm2. By this token, the nanostructure facilitates the osseointegration between the bone tissue and implant, and subsequently improves the performance in clinic
Ti nanorod arrays with controllable density on titanium surfaces were prepared by tuning the content of oxalic acid. The field emission scanning electron microscopy (FE-SEM) and atomic force microscope (AFM) were used to analyze the topography and density of titanium nanorod arrays. Bioactivity was investigated by immersing the samples in a simulated body fluid (2SBF) for 3 and 5 d. Results demonstrate that the different densities of nanorod arrays result from the change of the concentration of H+. The approach herein can be developed to be a facile nanotechnology for nano-functionalization of titanium. The structure of titanium nanorod arrays promotes the growth of calcium phosphate on the surface of the titanium, the mineralization ability is the best at density of (1.79 ± 0.04)×1010/cm2. By this token, the nanostructure facilitates the osseointegration between the bone tissue and implant, and subsequently improves the performance in clinic
29 Deformation Process Analysis and Pass Optimum Design for Continuous Rolling of Titanium Alloy Bars
2015, 44(8):2058-2062.
Abstract:
The existing flat triangle pass was improved in the "flat triangle-round" pass system of titanium alloy bar hot continuous rolling, based on analysis of rolling process and finite element simulation. Titanium alloy TC4 rod with Φ25 mm was rolled to that with Φ15 mm by the improved 8 stand tandem Y type rolling mill, aimed to solve the problems such as ears throughout the bar, twist and the poor roundness, and to improve the dimension precision of productions
The existing flat triangle pass was improved in the "flat triangle-round" pass system of titanium alloy bar hot continuous rolling, based on analysis of rolling process and finite element simulation. Titanium alloy TC4 rod with Φ25 mm was rolled to that with Φ15 mm by the improved 8 stand tandem Y type rolling mill, aimed to solve the problems such as ears throughout the bar, twist and the poor roundness, and to improve the dimension precision of productions
2015, 44(8):2063-2066.
Abstract:
Tungsten (W) powder was subjected to chemical activation pretreatment by immersion into an aqueous solution of hydrofluoric acid and ammonium fluoride, and then was reinforced with an ultrasonic wave at room temperature to obtain uniform distribution of defects (adsorbate island or steps, etc.) on the surface of W and TiC powder, increasing the surface activity of powder. W-1.5wt% TiC composites were prepared by a powder metallurgy method. A field emission electron microscope was employed to observe the surface topography of the original and chemically pretreated powder and fracture morphologies of W-1.5wt%TiC composites, and the sintering mechanism was discussed. The results show that under the condition of the same sintering process, the W-1.5wt%TiC composites after activation treatment of sintered powder achieve a relative density 7% higher than that of the original powder and more compact organization
Tungsten (W) powder was subjected to chemical activation pretreatment by immersion into an aqueous solution of hydrofluoric acid and ammonium fluoride, and then was reinforced with an ultrasonic wave at room temperature to obtain uniform distribution of defects (adsorbate island or steps, etc.) on the surface of W and TiC powder, increasing the surface activity of powder. W-1.5wt% TiC composites were prepared by a powder metallurgy method. A field emission electron microscope was employed to observe the surface topography of the original and chemically pretreated powder and fracture morphologies of W-1.5wt%TiC composites, and the sintering mechanism was discussed. The results show that under the condition of the same sintering process, the W-1.5wt%TiC composites after activation treatment of sintered powder achieve a relative density 7% higher than that of the original powder and more compact organization
2015, 44(8):2074-2080.
Abstract:
With the coming of the Clean Energy Revolution, using electric energy to power cars instead of gasoline has gradually come into the view of the public. Currently, electric cars employ lithium ion battery, but, limited by its theoretical specific energy, the endurance of these cars is far less than cars with internal combustion engines. Lithium-air battery, different from lithium ion battery, enjoys very high theoretical specific energy and is looking to replace lithium ion battery and becomes the core technology of electric car industry. Therefore, this paper summarizes the latest research and development of lithium-air battery in reaction mechanism, non-aqueous electrolyte, and air electrode, and gets a view of its future development
With the coming of the Clean Energy Revolution, using electric energy to power cars instead of gasoline has gradually come into the view of the public. Currently, electric cars employ lithium ion battery, but, limited by its theoretical specific energy, the endurance of these cars is far less than cars with internal combustion engines. Lithium-air battery, different from lithium ion battery, enjoys very high theoretical specific energy and is looking to replace lithium ion battery and becomes the core technology of electric car industry. Therefore, this paper summarizes the latest research and development of lithium-air battery in reaction mechanism, non-aqueous electrolyte, and air electrode, and gets a view of its future development
