Volume 34,Issue 6,2005 Table of Contents
2005, 34(6):841-844.
Abstract:
A review of research development of surface modification of Zircaloy is presented. Pre-film, ion-implantation and laser surface treatment are mainly summarized. For pre-film methods, pre-oxidation in autoclave, evaporated coatings and anodic oxidation are briefly introduced, then, the effect and principle of Y, La and Nb are explained for ion-implantation, finally, the research progress of laser surface melting (LSM) and laser surface alloying (LSA) is presented for laser surface treatments.
A review of research development of surface modification of Zircaloy is presented. Pre-film, ion-implantation and laser surface treatment are mainly summarized. For pre-film methods, pre-oxidation in autoclave, evaporated coatings and anodic oxidation are briefly introduced, then, the effect and principle of Y, La and Nb are explained for ion-implantation, finally, the research progress of laser surface melting (LSM) and laser surface alloying (LSA) is presented for laser surface treatments.
2005, 34(6):845-849.
Abstract:
研究不同变形条件对Mg-2.2Nd-0.5Zn-0.5Zr合金室温拉伸性能和组织的影响.经过不同条件的热挤压变形后,该合金的强度和延性都有不同程度的增加,屈强比从0.58提高到0.87左右.固定变形温度时,强度随变形速率增大而降低,延性反之.固定变形速率时,升高变形温度则强度降低,延性增加.弥散于晶界的Mg9Nd化合物细化了晶粒.变形态Mg-Nd合金的高温超塑拉伸研究发现,375℃是该合金的最佳超塑变形温度,应变速率在1×10-2s-1时,延伸率达到329%;当变形速率提高到2×10-2s-1时,该合金的延伸率仍可达到213%.分析不同真应变下的组织发现,在变形初期发生动态再结晶,晶粒得到破碎而变得细小,随着变形程度的增加,晶粒长大程度较小.在变形后的断口形貌中发现,Mg-Nd合金的超塑变形机制为晶界滑移控制下的孔洞连接协调机制.
研究不同变形条件对Mg-2.2Nd-0.5Zn-0.5Zr合金室温拉伸性能和组织的影响.经过不同条件的热挤压变形后,该合金的强度和延性都有不同程度的增加,屈强比从0.58提高到0.87左右.固定变形温度时,强度随变形速率增大而降低,延性反之.固定变形速率时,升高变形温度则强度降低,延性增加.弥散于晶界的Mg9Nd化合物细化了晶粒.变形态Mg-Nd合金的高温超塑拉伸研究发现,375℃是该合金的最佳超塑变形温度,应变速率在1×10-2s-1时,延伸率达到329%;当变形速率提高到2×10-2s-1时,该合金的延伸率仍可达到213%.分析不同真应变下的组织发现,在变形初期发生动态再结晶,晶粒得到破碎而变得细小,随着变形程度的增加,晶粒长大程度较小.在变形后的断口形貌中发现,Mg-Nd合金的超塑变形机制为晶界滑移控制下的孔洞连接协调机制.
2005, 34(6):850-853.
Abstract:
采用悬浮熔炼方法合成了FeSb合金，并研究了其作为锂离子电池负极材料的电化学性能。结果发现，虽然FeSb的容量低于纯锑。但其循环稳定性要优于纯锑。本实验采用恒电流间隙滴定技术(GITT)测定了在嵌锂过程中锂离子的化学扩散系数，在30℃时，该值在10^-12cm^2s^-1～10^-10cm^2s^-1范围内。
采用悬浮熔炼方法合成了FeSb合金，并研究了其作为锂离子电池负极材料的电化学性能。结果发现，虽然FeSb的容量低于纯锑。但其循环稳定性要优于纯锑。本实验采用恒电流间隙滴定技术(GITT)测定了在嵌锂过程中锂离子的化学扩散系数，在30℃时，该值在10^-12cm^2s^-1～10^-10cm^2s^-1范围内。
2005, 34(6):859-862.
Abstract:
通过对Mg(2-x)MxNi(M=Ti，Ag，Al)储氢合金材料的焓变、熵变、吸氢量与组成和键参数之间关系的分析，建立了焓变、熵变和吸氢量的半经验数学模型，得出影响焓变、熵变、平衡氢压和吸氢量的主要因素及其显著性的大小。结果表明：在所研究的合金体系中，电负性差△X和弹性模量G增大，则氢化物的生成焓△H^0负值减小，原子尺寸δ增大时，氢化物的H^0负值增大。氢化物的△S^0随着△X增大而增大。合金弹性模量、原子尺寸、电荷半径和温度越高，材料的储氢量越大，而电子密度越大，材料的储氢量反而越小。
通过对Mg(2-x)MxNi(M=Ti，Ag，Al)储氢合金材料的焓变、熵变、吸氢量与组成和键参数之间关系的分析，建立了焓变、熵变和吸氢量的半经验数学模型，得出影响焓变、熵变、平衡氢压和吸氢量的主要因素及其显著性的大小。结果表明：在所研究的合金体系中，电负性差△X和弹性模量G增大，则氢化物的生成焓△H^0负值减小，原子尺寸δ增大时，氢化物的H^0负值增大。氢化物的△S^0随着△X增大而增大。合金弹性模量、原子尺寸、电荷半径和温度越高，材料的储氢量越大，而电子密度越大，材料的储氢量反而越小。
2005, 34(6):863-866.
Abstract:
Tungsten fiber reinforced Zr-Ti-Cu-Be-Co bulk metallic amorphous matrix composite was fabricated by a pressure infiltrating cast method. The deformation behaviors and mechanical properties were investigated. The results indicated that Tungsten fiber reinforced bulk metallic glass matrix composite not only holds high strength of pure Zr-Ti-Cu-Be-Co bulk metallic glass, but also exhibits the strain of more than 900% higher than those of pure Zr-Ti-Cu-Be-Co bulk metallic glass. The compressive failure mode of the composite shifts from shear to the localized fiber buckling and tilting with the increase of the volume fraction of tungsten fibers. The increase in compressive toughness comes from the fibers restricting shear band propagation, promoting the generation of multiple shear bands.
Tungsten fiber reinforced Zr-Ti-Cu-Be-Co bulk metallic amorphous matrix composite was fabricated by a pressure infiltrating cast method. The deformation behaviors and mechanical properties were investigated. The results indicated that Tungsten fiber reinforced bulk metallic glass matrix composite not only holds high strength of pure Zr-Ti-Cu-Be-Co bulk metallic glass, but also exhibits the strain of more than 900% higher than those of pure Zr-Ti-Cu-Be-Co bulk metallic glass. The compressive failure mode of the composite shifts from shear to the localized fiber buckling and tilting with the increase of the volume fraction of tungsten fibers. The increase in compressive toughness comes from the fibers restricting shear band propagation, promoting the generation of multiple shear bands.
2005, 34(6):872-875.
Abstract:
Based on Ansys software, the influences of shape, size, position and pitch of holes on AZ91D Mg alloy die casting stress distribution were studied. The results show that the influences of shape of hole on stress distribution lie on the minimum included angle formed by two lines, one line is x axis, the other is the tie line of sharp corner apex and center of hole. The stress concentration increases with the increases of the minimum inclination and the size of hole. The influence effect of the open hole is greater than the inner hole. The influence is very faint when the pitch of holes is beyond a critical value, and the stress concentration increases quickly with the decrease of the pitch of holes. Lastly, the hole distribution and the strength of AZ91D Mg alloy for engine head mantle die casting are actually measured. It is shown that the results of theoretical analysis are in consonance with the experiments.
Based on Ansys software, the influences of shape, size, position and pitch of holes on AZ91D Mg alloy die casting stress distribution were studied. The results show that the influences of shape of hole on stress distribution lie on the minimum included angle formed by two lines, one line is x axis, the other is the tie line of sharp corner apex and center of hole. The stress concentration increases with the increases of the minimum inclination and the size of hole. The influence effect of the open hole is greater than the inner hole. The influence is very faint when the pitch of holes is beyond a critical value, and the stress concentration increases quickly with the decrease of the pitch of holes. Lastly, the hole distribution and the strength of AZ91D Mg alloy for engine head mantle die casting are actually measured. It is shown that the results of theoretical analysis are in consonance with the experiments.
2005, 34(6):876-880.
Abstract:
Three different compositions of NbTi wires have been fabricated by using alternately pure Nb and Ti sheets with Ti contents from 42.5% to 56.6% by adjusting the relative thickness of the Nb and Ti sheets in the monofilaments. Two kinds of heating treatments were discussed and the Nb/Ti interface microstructure and diffusion morphology of cross-section have been investigated by scanning electron microscopy (SEM). The results show that the Jc values are 2 800 A/mm2 at 5 T/4.2K and 4 200 A/mm2 at 3 T/4.2 K. With the increase of Ti content, Jc is higher at low magnetic fields (<5 T), but lower and decreasing rapidly at high magnetic fields. Jc decreases slight slowly for the lower Ti samples. At a given temperature, higher Jc can be gotten by using shorter time of heat treatment for the higher Ti samples, and by using longer time for the lower Ti samples.
Three different compositions of NbTi wires have been fabricated by using alternately pure Nb and Ti sheets with Ti contents from 42.5% to 56.6% by adjusting the relative thickness of the Nb and Ti sheets in the monofilaments. Two kinds of heating treatments were discussed and the Nb/Ti interface microstructure and diffusion morphology of cross-section have been investigated by scanning electron microscopy (SEM). The results show that the Jc values are 2 800 A/mm2 at 5 T/4.2K and 4 200 A/mm2 at 3 T/4.2 K. With the increase of Ti content, Jc is higher at low magnetic fields (<5 T), but lower and decreasing rapidly at high magnetic fields. Jc decreases slight slowly for the lower Ti samples. At a given temperature, higher Jc can be gotten by using shorter time of heat treatment for the higher Ti samples, and by using longer time for the lower Ti samples.
2005, 34(6):881-885.
Abstract:
研究了Ti-13Nb-13Zr合金在β相区和α β相区固溶和时效处理后合金的力学性能变化规律。利用光学显微镜、扫描电镜和透射电镜观察和X射线衍射分析，重点分析了不同显微组织对合金强韧性的影响。结果表明：含有一定数量初生α析出相的加工态组织具有较高的强度和断裂韧性。固溶时效处理后，随着显微组织的形貌、晶粒大小和数量的不同，其对强度和断裂韧性的影响也有所不同。
研究了Ti-13Nb-13Zr合金在β相区和α β相区固溶和时效处理后合金的力学性能变化规律。利用光学显微镜、扫描电镜和透射电镜观察和X射线衍射分析，重点分析了不同显微组织对合金强韧性的影响。结果表明：含有一定数量初生α析出相的加工态组织具有较高的强度和断裂韧性。固溶时效处理后，随着显微组织的形貌、晶粒大小和数量的不同，其对强度和断裂韧性的影响也有所不同。
2005, 34(6):886-890.
Abstract:
采用超声波化学镀的方法，在SnO2粉末表面包覆Ag，获得超细的Ag-SnO2复合粉末，并用粉末冶金工芝，制备出AgSnO2触头材料。研究中发现，粉末中存在的杂质导致AgSnO2材料的压力加工性能显著下降。通过金相组织及电子显微镜(SEM)的形貌观察、能谱成分分析（EDX)等手段，对烧结试样的组织进行了深入研究。结果表明：化学镀银时所用AgNO3中的杂质阻止了Ag-SnO2粉末在烧结过程的融合长大．导致粉末之间形成大量的孔洞及三角界面。使粉末之间结合力下降，材料的压力加工性能变差差。基于上述研究结果，制备出密度为9．98g/cm63，电阻率低至2.13μΩcm，并具有优异的加工性能的AgSnO2材料。
采用超声波化学镀的方法，在SnO2粉末表面包覆Ag，获得超细的Ag-SnO2复合粉末，并用粉末冶金工芝，制备出AgSnO2触头材料。研究中发现，粉末中存在的杂质导致AgSnO2材料的压力加工性能显著下降。通过金相组织及电子显微镜(SEM)的形貌观察、能谱成分分析（EDX)等手段，对烧结试样的组织进行了深入研究。结果表明：化学镀银时所用AgNO3中的杂质阻止了Ag-SnO2粉末在烧结过程的融合长大．导致粉末之间形成大量的孔洞及三角界面。使粉末之间结合力下降，材料的压力加工性能变差差。基于上述研究结果，制备出密度为9．98g/cm63，电阻率低至2.13μΩcm，并具有优异的加工性能的AgSnO2材料。
2005, 34(6):891-894.
Abstract:
采用大变形锻造法，研究了7075铝合金在低温大变形下的显微组织的演化，为制取超细晶组织提供一个新的方法。利用透射电子显微镜分析了合金在不同条件下的组织形貌特征。结果表明，通过超低温大变形能够得到超细晶组织，晶粒尺寸约为0．5μm。对本实验中没有发现形变孪晶的原因进行了讨论。合金的变形机制主要是位错滑移，晶粒碎化和几何动态再结晶机制。
采用大变形锻造法，研究了7075铝合金在低温大变形下的显微组织的演化，为制取超细晶组织提供一个新的方法。利用透射电子显微镜分析了合金在不同条件下的组织形貌特征。结果表明，通过超低温大变形能够得到超细晶组织，晶粒尺寸约为0．5μm。对本实验中没有发现形变孪晶的原因进行了讨论。合金的变形机制主要是位错滑移，晶粒碎化和几何动态再结晶机制。
2005, 34(6):899-902.
Abstract:
Laser surface alloying with C and C+Nb was used to modify the surface properties of Ti-46Al-2Cr-1.5Nb-lV alloy. The microstructure of the laser alloyed surface layer was studied as function of laser processing parameters. The oxidation resistance properties of the original alloy and the samples with the laser surface treatment with C and C+ Nb at high temperature were investigated. The results indicate that, by laser alloying with with C and C+Nb, the particles of TiC were "in-situ" produced in the laser surface layer. Nb exists in the TiAl matrix as the solute atom. The size, shape and distribution of TiC are strongly dependent on the laser processing parameters. By laser surface alloying with C and C+Nb powders, the oxidation resistance is improved obviously, and the sample alloying with C+Nb exhibits the best oxidation resistance.
Laser surface alloying with C and C+Nb was used to modify the surface properties of Ti-46Al-2Cr-1.5Nb-lV alloy. The microstructure of the laser alloyed surface layer was studied as function of laser processing parameters. The oxidation resistance properties of the original alloy and the samples with the laser surface treatment with C and C+ Nb at high temperature were investigated. The results indicate that, by laser alloying with with C and C+Nb, the particles of TiC were "in-situ" produced in the laser surface layer. Nb exists in the TiAl matrix as the solute atom. The size, shape and distribution of TiC are strongly dependent on the laser processing parameters. By laser surface alloying with C and C+Nb powders, the oxidation resistance is improved obviously, and the sample alloying with C+Nb exhibits the best oxidation resistance.
2005, 34(6):903-906.
Abstract:
Magnesium has almost the same density, elastic modulus and strength as human bone. In fact human body contains much more magnesium than titanium. The challenge of magnesium is to improve its corrosion and biocompatibility to body fluids while it is used as implants. This paper reports the results of a study in which untreated or treated magnesium samples were subjected to cyto-compatibility tests and hemolysis tests. The results show that no the change of cells morphological or inhibitory effect on cell growth were detected in the cyto-compatibility tests. In hemolysis tests, the untreated magnesium had hemolytic effect, whereas the hemolysis of heat-treated and heatorganic filmtreated samples is within the demand (<5%). Therefore, it is very possible to use magnesium and its alloys as hard tissue substitutes if their surface is properly modified.
Magnesium has almost the same density, elastic modulus and strength as human bone. In fact human body contains much more magnesium than titanium. The challenge of magnesium is to improve its corrosion and biocompatibility to body fluids while it is used as implants. This paper reports the results of a study in which untreated or treated magnesium samples were subjected to cyto-compatibility tests and hemolysis tests. The results show that no the change of cells morphological or inhibitory effect on cell growth were detected in the cyto-compatibility tests. In hemolysis tests, the untreated magnesium had hemolytic effect, whereas the hemolysis of heat-treated and heatorganic filmtreated samples is within the demand (<5%). Therefore, it is very possible to use magnesium and its alloys as hard tissue substitutes if their surface is properly modified.
2005, 34(6):907-911.
Abstract:
The influence of heat and force factors and their interaction, such as forging temperature, heat treatment process, deformation amount, on the element diffusion of Al, Nb, V at weld zone has been investigated for the Ti-24Al-15Nb-1.5Mo/TC4 dual alloy billet after welded in vacuum and rolled or treated. Investigations showed that the energy of atom motion can increase with the increase of deformation amount and heat treatment temperature, favorable for the elements diffusion and the homogenization of micro-hardness due to the change of shape and size for the grains and phases and short diffusion journey of fine grains at the weld seam. It is found that the concentration of niobium is high at the Ti-24Al-15Nb-1.5Mo side of weld seam. There are two reasons: one is niobium diffusion out from DO19 lattice when re-solidified during welding; the other is local deposit of niobium to fill up the vacancies when AI, Mo diffused out the lattice. The heat treatment route can affect the diffusion rate through changing the morphology of microstructure at weld zone.
The influence of heat and force factors and their interaction, such as forging temperature, heat treatment process, deformation amount, on the element diffusion of Al, Nb, V at weld zone has been investigated for the Ti-24Al-15Nb-1.5Mo/TC4 dual alloy billet after welded in vacuum and rolled or treated. Investigations showed that the energy of atom motion can increase with the increase of deformation amount and heat treatment temperature, favorable for the elements diffusion and the homogenization of micro-hardness due to the change of shape and size for the grains and phases and short diffusion journey of fine grains at the weld seam. It is found that the concentration of niobium is high at the Ti-24Al-15Nb-1.5Mo side of weld seam. There are two reasons: one is niobium diffusion out from DO19 lattice when re-solidified during welding; the other is local deposit of niobium to fill up the vacancies when AI, Mo diffused out the lattice. The heat treatment route can affect the diffusion rate through changing the morphology of microstructure at weld zone.
2005, 34(6):912-915.
Abstract:
Adopting bonding technology, the giant magnetostrictive composites have been prepared. The effects of preparation conditions, such as powder composition, powder size, magnetic field orientation and powder surface treatment, on the static elastic modulus and compressive strength for the giant magnetostrictive composites have been investigated in this paper. It is found that the powder size and the powder surface treatment have obvious effects on the static elastic modulus and compressive strength, and few effect for the powder composition and the magnetic field orientation, but the powder composition has effects on the static elastic modulus.
Adopting bonding technology, the giant magnetostrictive composites have been prepared. The effects of preparation conditions, such as powder composition, powder size, magnetic field orientation and powder surface treatment, on the static elastic modulus and compressive strength for the giant magnetostrictive composites have been investigated in this paper. It is found that the powder size and the powder surface treatment have obvious effects on the static elastic modulus and compressive strength, and few effect for the powder composition and the magnetic field orientation, but the powder composition has effects on the static elastic modulus.
2005, 34(6):916-919.
Abstract:
研究了Ir/Re喷管制备过程中的Ir/Mo互扩散问题。在电子探针测量的基础上,根据扩散理论和Ir-Mo相图数据,建立并推导Ir/Mo扩散模型和解。计算得到Ir3Mo相中的互扩散系数为:D=9.0×10-9exp(-1.46eV/kT)(cm2/s),Ir基固溶体中的互扩散系数为:D=5.0×10-10exp(-1.1eV/kT)(cm2/s)。确定喷管中Ir/Mo互扩散的特点,给出估算Ir3Mo相层厚的方法。确定Re在Ir3Mo相中的扩散主要是受Ir控制。
研究了Ir/Re喷管制备过程中的Ir/Mo互扩散问题。在电子探针测量的基础上,根据扩散理论和Ir-Mo相图数据,建立并推导Ir/Mo扩散模型和解。计算得到Ir3Mo相中的互扩散系数为:D=9.0×10-9exp(-1.46eV/kT)(cm2/s),Ir基固溶体中的互扩散系数为:D=5.0×10-10exp(-1.1eV/kT)(cm2/s)。确定喷管中Ir/Mo互扩散的特点,给出估算Ir3Mo相层厚的方法。确定Re在Ir3Mo相中的扩散主要是受Ir控制。
2005, 34(6):920-923.
Abstract:
Secondary ion mass spectra analysis (SIMS) has been employed to construct the diffusion model of Ga in SiO2/Si system during doping and to study the distribution of Ga in silicon. Based on the above model, conclusions have been drawn as following: (1) Ga has a linear distribution and enters Si due to the segregation of SiO2/Si interface. As a result, the diffusion model of Ga was established. (2) Through controlling the temperature and adjusting the time during pre-deposition, and combination of them, an idea purity distribution can be obtained. (3) The planar junction with high uniformity and good repetition will be obtained by the above process, indicating that Ga has ideally diffused into silicon through the perfect interface.
Secondary ion mass spectra analysis (SIMS) has been employed to construct the diffusion model of Ga in SiO2/Si system during doping and to study the distribution of Ga in silicon. Based on the above model, conclusions have been drawn as following: (1) Ga has a linear distribution and enters Si due to the segregation of SiO2/Si interface. As a result, the diffusion model of Ga was established. (2) Through controlling the temperature and adjusting the time during pre-deposition, and combination of them, an idea purity distribution can be obtained. (3) The planar junction with high uniformity and good repetition will be obtained by the above process, indicating that Ga has ideally diffused into silicon through the perfect interface.
2005, 34(6):924-927.
Abstract:
A new type of silver tin oxide contact material was fabricated by reaction synthesis processing and hot extrusion in the paper. The phases of AgSnO2 (10) after reaction synthesis processing were determined by X-ray diffraction. Electrical contact life of AgSnO2(10) were experimented with direct current. The surface morphologies of melting range was examined by scanning electron microscope(SEM), and the element compositions of surface were analyzed by electro-probe microanalyser (EPMA), the microstructure and composition of the surface of arc erosion are also analyzed. Four kinds surface morphologies of the AgSnO2(10) materials were classified.
A new type of silver tin oxide contact material was fabricated by reaction synthesis processing and hot extrusion in the paper. The phases of AgSnO2 (10) after reaction synthesis processing were determined by X-ray diffraction. Electrical contact life of AgSnO2(10) were experimented with direct current. The surface morphologies of melting range was examined by scanning electron microscope(SEM), and the element compositions of surface were analyzed by electro-probe microanalyser (EPMA), the microstructure and composition of the surface of arc erosion are also analyzed. Four kinds surface morphologies of the AgSnO2(10) materials were classified.
2005, 34(6):928-931.
Abstract:
CeO2 superfine powder was well prepared by laser heating gas-evaporation method with a 150 W CW CO2 laser as light source and Ce2(CO3)3 as targets. All the effects of process reaction parameters on products have been well researched. Measurements such as XRD, TEM were used to characterize the superfine particles. The obtained results show that many parameters such as the laser power density, reaction pressure, sort and rate of airflows affect the size and morphorlogy of nanoparticles. The size of the particle changes within 50 nm-80 nm in Ar atmosphere, and 10 nm-20 nm in deoxidization atmosphere of H2.
CeO2 superfine powder was well prepared by laser heating gas-evaporation method with a 150 W CW CO2 laser as light source and Ce2(CO3)3 as targets. All the effects of process reaction parameters on products have been well researched. Measurements such as XRD, TEM were used to characterize the superfine particles. The obtained results show that many parameters such as the laser power density, reaction pressure, sort and rate of airflows affect the size and morphorlogy of nanoparticles. The size of the particle changes within 50 nm-80 nm in Ar atmosphere, and 10 nm-20 nm in deoxidization atmosphere of H2.
2005, 34(6):932-935.
Abstract:
Monodispersed spherical Y2O3:Eu3+ nanocrystallines were successfully prepared by a novel gel-network coprecipitition process. The effect of reaction conditions on the resulting particles was investigated. XRD,TEM and fluoresce spectra were used to characterize the samples. The results show that the samples were spherical with a particle size of 13 nm-25 nm. Compared with micronscale Y2O3:Eu3+, a clear red shift occurs in the excitation spectrum of Y2O3:Eu3+ nanocrystalline prepared by the present work.
Monodispersed spherical Y2O3:Eu3+ nanocrystallines were successfully prepared by a novel gel-network coprecipitition process. The effect of reaction conditions on the resulting particles was investigated. XRD,TEM and fluoresce spectra were used to characterize the samples. The results show that the samples were spherical with a particle size of 13 nm-25 nm. Compared with micronscale Y2O3:Eu3+, a clear red shift occurs in the excitation spectrum of Y2O3:Eu3+ nanocrystalline prepared by the present work.
2005, 34(6):936-939.
Abstract:
A wear resistant Cr13Ni5Si2-based metal silicide coating was fabricated on a substrate of titanium alloy BT20 by laser cladding process of Cr-Ni-Si alloy powders. Wear resistance of the coating was evaluated under block-on-wheel dry sliding wear test conditions at room-temperature. Microstructure of the coating is consisted of Cr13Ni5Si2 primary dendrites and small amount of Cr13Ni5Si2/ Cr3Ni5Si2 eutectics. The laser-clad Cr13Ni5Si2-based coating exhibited an excellent wear resistance under dry sliding wear test conditions.
A wear resistant Cr13Ni5Si2-based metal silicide coating was fabricated on a substrate of titanium alloy BT20 by laser cladding process of Cr-Ni-Si alloy powders. Wear resistance of the coating was evaluated under block-on-wheel dry sliding wear test conditions at room-temperature. Microstructure of the coating is consisted of Cr13Ni5Si2 primary dendrites and small amount of Cr13Ni5Si2/ Cr3Ni5Si2 eutectics. The laser-clad Cr13Ni5Si2-based coating exhibited an excellent wear resistance under dry sliding wear test conditions.
2005, 34(6):940-942.
Abstract:
Sm2(Fe,M)17 (M=Nb) alloy is prepared through HDDR (Hydrogen-Disproportionation-Desorption-Recombination) method. Influence of Nb element addition on the microstrcuture of Sm2Fe17 alloy was studied. The results show that the as-cast structure of Sm2(Fe,M)17(M=Nb) alloy can be improved effectively.
Sm2(Fe,M)17 (M=Nb) alloy is prepared through HDDR (Hydrogen-Disproportionation-Desorption-Recombination) method. Influence of Nb element addition on the microstrcuture of Sm2Fe17 alloy was studied. The results show that the as-cast structure of Sm2(Fe,M)17(M=Nb) alloy can be improved effectively.
2005, 34(6):943-945.
Abstract:
在乙醇和水的混合溶剂中合成了均苯四甲酸(H4L)铕发光配合物。通过元素、化学分析、红外光谱确定其化学组成为Eu4/3L·7H2O。热分析表明,配合物在530℃以下稳定性较好,X射线衍射结果表明,配合物为晶体物质,扫描电镜照片表明配合物为块状物质,晶粒10μm-20μm,荧光光谱分析表明配合物在紫外光的激发下发出铕的特征荧光。
在乙醇和水的混合溶剂中合成了均苯四甲酸(H4L)铕发光配合物。通过元素、化学分析、红外光谱确定其化学组成为Eu4/3L·7H2O。热分析表明,配合物在530℃以下稳定性较好,X射线衍射结果表明,配合物为晶体物质,扫描电镜照片表明配合物为块状物质,晶粒10μm-20μm,荧光光谱分析表明配合物在紫外光的激发下发出铕的特征荧光。
2005, 34(6):946-949.
Abstract:
Carbon/carbon composite has good mechanical properties and biocompatibility, but has no bioactivity. Titanium oxide film was deposited onto the carbon-carbon composite using ion beam enhanced deposition, then subjected to alkali treatment, heat treatment in vacuum, immersion in the simulated body fluid (SBF) and scratch test. It was found that a porous network of sodium titanate gel was formed after the titanium oxide film was alkali treated, and the gel layer could induce deposition of bioactive apatite layer in SBF. The porous gel layer became denser and the apatite deposition rate was decreased after heat treatment. The scratch test showed that the bonding strength of the alkali treated titanium oxide film was slightly increased after heat treatment, but bonding strength of the films was limited by the soft carbon/carbon composite substrate.
Carbon/carbon composite has good mechanical properties and biocompatibility, but has no bioactivity. Titanium oxide film was deposited onto the carbon-carbon composite using ion beam enhanced deposition, then subjected to alkali treatment, heat treatment in vacuum, immersion in the simulated body fluid (SBF) and scratch test. It was found that a porous network of sodium titanate gel was formed after the titanium oxide film was alkali treated, and the gel layer could induce deposition of bioactive apatite layer in SBF. The porous gel layer became denser and the apatite deposition rate was decreased after heat treatment. The scratch test showed that the bonding strength of the alkali treated titanium oxide film was slightly increased after heat treatment, but bonding strength of the films was limited by the soft carbon/carbon composite substrate.
2005, 34(6):950-953.
Abstract:
Physico-chemical characterization of commercially available Pt/C catalysts before and after methanol oxidation experiments was carried out by X-ray diffraction, scanning electron microscope and transmission electron microscopy. Meanwhile, the electrocatalytic performance of the glassy carbon electrode modified with the carbon supported Pt nanoparticles for the oxidation of methanol has been studied by means of electrochemical method. The experimental results showed that the Pt/C/GC electrode had high electrocatalytic activity for the electrocatalytic oxidation of methanol. The electrochemical reduction of the Pt oxide is inhibited owing to the strong binding of Pt to the support in the Pt/C catalyst. By means of SEM and cyclic voltammetric studies, it was shown that a surface structure-sensitive effect might exist during electrooxidation of methanol on Pt/C catalyst.
Physico-chemical characterization of commercially available Pt/C catalysts before and after methanol oxidation experiments was carried out by X-ray diffraction, scanning electron microscope and transmission electron microscopy. Meanwhile, the electrocatalytic performance of the glassy carbon electrode modified with the carbon supported Pt nanoparticles for the oxidation of methanol has been studied by means of electrochemical method. The experimental results showed that the Pt/C/GC electrode had high electrocatalytic activity for the electrocatalytic oxidation of methanol. The electrochemical reduction of the Pt oxide is inhibited owing to the strong binding of Pt to the support in the Pt/C catalyst. By means of SEM and cyclic voltammetric studies, it was shown that a surface structure-sensitive effect might exist during electrooxidation of methanol on Pt/C catalyst.
2005, 34(6):954-958.
Abstract:
通过实施不同的退火热处理工艺，调整合金中强化相的析出状态，制备具有不同退火状态的几组拉伸试样。对每组试样在未充氢和充氢后按相同的条件进行拉伸试验对该组试样的脆化作用。通过比较不同组试样的脆化表现通过比较未充氢试样和充氢后试样的强度和塑性，评价氢考察退火状态对Inconel 718氢脆倾向的影响。试验结果表明，随着退火程度的加强，强化相体积分数减少，氢引起的塑性损失下降，即抗氢脆性能改善。该结果说明，强化相γ″和γ′对Inconel 718合金的氢脆有促进作用。因此，根据不同工业应用要求，在符合强度要求的前提下，可以通过热处理改善零件的抗氢脆性能。
通过实施不同的退火热处理工艺，调整合金中强化相的析出状态，制备具有不同退火状态的几组拉伸试样。对每组试样在未充氢和充氢后按相同的条件进行拉伸试验对该组试样的脆化作用。通过比较不同组试样的脆化表现通过比较未充氢试样和充氢后试样的强度和塑性，评价氢考察退火状态对Inconel 718氢脆倾向的影响。试验结果表明，随着退火程度的加强，强化相体积分数减少，氢引起的塑性损失下降，即抗氢脆性能改善。该结果说明，强化相γ″和γ′对Inconel 718合金的氢脆有促进作用。因此，根据不同工业应用要求，在符合强度要求的前提下，可以通过热处理改善零件的抗氢脆性能。
2005, 34(6):959-961.
Abstract:
The SiW12 modified Pt electrode was prepared by a cyclic voltammetry scan in H2SO4 containing SiW12. During the preparation of modified electrode, we found a redox reaction of SiW12 in hydrogen area on the Pt electrode, but the adsorption increasing for the particles containing Oxygen in Oxygen area on the electrode surface. The electrochemical behaviour of this modified electrode in H2SO4 and its electrocatalytic effect to methanol oxidation were studied by cyclic voltammograms and I-t curves of constant voltage. The results show that the Pt electrode modified by Silicatungstic acid has not only the higher catalytic activity to methanol oxidation, but also the effect decreasing CO poison.
The SiW12 modified Pt electrode was prepared by a cyclic voltammetry scan in H2SO4 containing SiW12. During the preparation of modified electrode, we found a redox reaction of SiW12 in hydrogen area on the Pt electrode, but the adsorption increasing for the particles containing Oxygen in Oxygen area on the electrode surface. The electrochemical behaviour of this modified electrode in H2SO4 and its electrocatalytic effect to methanol oxidation were studied by cyclic voltammograms and I-t curves of constant voltage. The results show that the Pt electrode modified by Silicatungstic acid has not only the higher catalytic activity to methanol oxidation, but also the effect decreasing CO poison.
2005, 34(6):962-965.
Abstract:
利用W，Mo，Si粉末燃烧合成复合发热元件原料，制备WSi2／MoSi2复合发热元件。通过显微结构和力学性能、物理性能的测试分析表明：复合发热元件显微组织细小、分布较均匀，结晶相主要是以固溶形式的(WxMoy)Si2以及少量(WxMoy)5Si3相存在(其中x y=1)，玻璃相是以SiO2和Al2O3为主，并含有少量的Na，Mg，K，Ca等金属氧化物；断口晶粒细小，主要表现为沿晶断裂，抗弯强度和显微硬度较高；复合发热元件电阻率与MoSi2发热元件相近，没有老化现象：烧损温度高于MoSi2发热元件80℃，热膨胀系数低于MoSi2发热元件，热稳定性较好；复合发热元件表面膜是一种复合硅氧膜，成膜质量较好。
利用W，Mo，Si粉末燃烧合成复合发热元件原料，制备WSi2／MoSi2复合发热元件。通过显微结构和力学性能、物理性能的测试分析表明：复合发热元件显微组织细小、分布较均匀，结晶相主要是以固溶形式的(WxMoy)Si2以及少量(WxMoy)5Si3相存在(其中x y=1)，玻璃相是以SiO2和Al2O3为主，并含有少量的Na，Mg，K，Ca等金属氧化物；断口晶粒细小，主要表现为沿晶断裂，抗弯强度和显微硬度较高；复合发热元件电阻率与MoSi2发热元件相近，没有老化现象：烧损温度高于MoSi2发热元件80℃，热膨胀系数低于MoSi2发热元件，热稳定性较好；复合发热元件表面膜是一种复合硅氧膜，成膜质量较好。
2005, 34(6):966-969.
Abstract:
以H2WO4和CuSO4·H2O(W:Cu=70g:30g)为原料,采用化学共沉淀方法制备W-Cu化合物粉末,其反应条件为:反应温度25℃±1℃,pH值5.0-5.2,陈化时间8h±1h。设计了封闭循环氢还原系统,用此系统进行氢气热还原,不仅使氢气得到充分利用,而且容易判断反应终点。通过系统内的特殊装置除水,降低了还原温度,在600℃下还原得到W和Cu混合均匀的复合粉。其粒径小于70nm。
以H2WO4和CuSO4·H2O(W:Cu=70g:30g)为原料,采用化学共沉淀方法制备W-Cu化合物粉末,其反应条件为:反应温度25℃±1℃,pH值5.0-5.2,陈化时间8h±1h。设计了封闭循环氢还原系统,用此系统进行氢气热还原,不仅使氢气得到充分利用,而且容易判断反应终点。通过系统内的特殊装置除水,降低了还原温度,在600℃下还原得到W和Cu混合均匀的复合粉。其粒径小于70nm。
2005, 34(6):970-973.
Abstract:
采用Ti基活性钎料对高强石墨进行了高温钎焊试验。研究了焊接温度、保温时间、焊料量、降温速率对试样连接强度的影响。通过正交实验优选工艺，确定最佳工艺为：焊接温度1420℃，保温时间20min，焊料量280mg，降温速率10℃／min。所得连接件的最高相对抗弯强度为62．55％。微观结构研究表明，在石墨／焊料界面处C元素和Ti元素发生了显著的互扩散，生成了厚度约15μm的反应层，实现了良好的界面结合。接头区域XRD分析表明，在石墨／焊料界面上几乎全部为TiC，在焊料内部距此界面200μm处仍有部分TiC存在，但主相是纯Ti，还有部分Ti2Ni。在焊料内部距此界面400μm处主相是纯Ti，次相是Ti2Ni，无TiC存在。
采用Ti基活性钎料对高强石墨进行了高温钎焊试验。研究了焊接温度、保温时间、焊料量、降温速率对试样连接强度的影响。通过正交实验优选工艺，确定最佳工艺为：焊接温度1420℃，保温时间20min，焊料量280mg，降温速率10℃／min。所得连接件的最高相对抗弯强度为62．55％。微观结构研究表明，在石墨／焊料界面处C元素和Ti元素发生了显著的互扩散，生成了厚度约15μm的反应层，实现了良好的界面结合。接头区域XRD分析表明，在石墨／焊料界面上几乎全部为TiC，在焊料内部距此界面200μm处仍有部分TiC存在，但主相是纯Ti，还有部分Ti2Ni。在焊料内部距此界面400μm处主相是纯Ti，次相是Ti2Ni，无TiC存在。
2005, 34(6):974-977.
Abstract:
Six kinds of cladding combination of nanometal with one or two layers were electrodeposited on the surface of NdFeB powders. The electrode potential of those powders were measured to be a mixed potential combined NdFeB and deposited metals. It was shown that the properties of magnetic powder were related to the property of deposited metals. The resistivity of magnets showed the mixed resistivity of NdFeB and deposited metals. It was found that the resistivity of the sample deposited by the nano-Zn/Ni film increased abnormally, and its (BH)m and Hc decreased in various degrees.
Six kinds of cladding combination of nanometal with one or two layers were electrodeposited on the surface of NdFeB powders. The electrode potential of those powders were measured to be a mixed potential combined NdFeB and deposited metals. It was shown that the properties of magnetic powder were related to the property of deposited metals. The resistivity of magnets showed the mixed resistivity of NdFeB and deposited metals. It was found that the resistivity of the sample deposited by the nano-Zn/Ni film increased abnormally, and its (BH)m and Hc decreased in various degrees.
2005, 34(6):978-981.
Abstract:
The feasibility of Al2O3p/6061Al composites materials brazing in resistance furnace protected by argon gas is investigated. Results show that the brazed joint with good quality can be got by using the reasonable brazing filler metal and proper brazing flux (HL401+QJ201) and the optimum brazing technological parameters. The mechanical properties of brazed joint, such as shearing strengthen and microhardness have been tested, and the microstructure analyses such as metallographic observation, XRD and SEM, have been done to discuss the mechanism of the brazed joint forming in theory, providing some information on how to get excellent brazed joint.
The feasibility of Al2O3p/6061Al composites materials brazing in resistance furnace protected by argon gas is investigated. Results show that the brazed joint with good quality can be got by using the reasonable brazing filler metal and proper brazing flux (HL401+QJ201) and the optimum brazing technological parameters. The mechanical properties of brazed joint, such as shearing strengthen and microhardness have been tested, and the microstructure analyses such as metallographic observation, XRD and SEM, have been done to discuss the mechanism of the brazed joint forming in theory, providing some information on how to get excellent brazed joint.
2005, 34(6):982-985.
Abstract:
研究了H2压力、温度对NdFeB铸块和铸片吸氢的影响。结果表明,NdFeB铸块和铸片在吸氢过程中均明显存在孕育期,其吸氢过程均可分为4个阶段:孕育期阶段、慢速吸氢阶段、快速吸氢阶段和缓慢吸氢阶段。随着H2压力(1×lO5Pa-4×105Pa)和温度(293K-373K)的升高,NdFeB铸块和铸片的吸氢速度加快,孕育期缩短。且当温度升至一定程度时,铸块的孕育期消失,而铸片的吸氢始终存在孕育期。铸片吸氢过程中的Ⅰ,Ⅱ,Ⅲ阶段的吸氢时间均明显长于铸块,而第Ⅳ阶段的吸氢时间则较短。研究同时表明,NdFeB铸块和铸片的吸氢量几乎不受氢气压力的影响,但随温度的升高,吸氢量减少。
研究了H2压力、温度对NdFeB铸块和铸片吸氢的影响。结果表明,NdFeB铸块和铸片在吸氢过程中均明显存在孕育期,其吸氢过程均可分为4个阶段:孕育期阶段、慢速吸氢阶段、快速吸氢阶段和缓慢吸氢阶段。随着H2压力(1×lO5Pa-4×105Pa)和温度(293K-373K)的升高,NdFeB铸块和铸片的吸氢速度加快,孕育期缩短。且当温度升至一定程度时,铸块的孕育期消失,而铸片的吸氢始终存在孕育期。铸片吸氢过程中的Ⅰ,Ⅱ,Ⅲ阶段的吸氢时间均明显长于铸块,而第Ⅳ阶段的吸氢时间则较短。研究同时表明,NdFeB铸块和铸片的吸氢量几乎不受氢气压力的影响,但随温度的升高,吸氢量减少。
2005, 34(6):986-989.
Abstract:
采用高功率连续波固体Nd：YAG激光辐照，在置于N2反应室中的NiTi形状记忆合金表面制备激光气体氮化层。实验表明：选择适当的激光辐照工艺参数，可获得致密的TIN增强金属基复合材料(MMC)梯度涂层，改性层的表面被厚度为1μm～2μm的TIN陶瓷层封闭，涂层内部TIN增强相呈梯度分布。扫描电镜(SEM)及能谱(EDX)分析结果表明，MMC改性层与基体NiTi合金间存在良好的冶金结合，界面处成分均匀过渡，表面Ni含量极低。显微硬度测试及磨损试验结果表明，激光气体氮化显著提高了NiTi合金的表面硬度和耐磨性。说明激光表面改性有效地改善了NiTi形状记忆合金作为生物医学材料使用的表面成分和性能，并将有效地抑制有害元素Ni^2 的释放。
采用高功率连续波固体Nd：YAG激光辐照，在置于N2反应室中的NiTi形状记忆合金表面制备激光气体氮化层。实验表明：选择适当的激光辐照工艺参数，可获得致密的TIN增强金属基复合材料(MMC)梯度涂层，改性层的表面被厚度为1μm～2μm的TIN陶瓷层封闭，涂层内部TIN增强相呈梯度分布。扫描电镜(SEM)及能谱(EDX)分析结果表明，MMC改性层与基体NiTi合金间存在良好的冶金结合，界面处成分均匀过渡，表面Ni含量极低。显微硬度测试及磨损试验结果表明，激光气体氮化显著提高了NiTi合金的表面硬度和耐磨性。说明激光表面改性有效地改善了NiTi形状记忆合金作为生物医学材料使用的表面成分和性能，并将有效地抑制有害元素Ni^2 的释放。
2005, 34(6):990-993.
Abstract:
Cu(NO3)2and (NH4)2Mo2O7 were used to fabricate Mo/Cu composite nanopowders by sol-gel technique. The influences of heat treatment process, solution pH value and the addition agent on the particle size were investigated by DTA-TG, XRD and TEM. The results show that under certain heat treatment temperature, the quantity of the addition agent influences the grain size of nanoparticle. When the quantity ratio of addition agent is 0.5, we can get fine nanoparticles with small grain size and homogeneous granularity. The particle sizes are varied under various solution acidities. When pH values change form 1 to 4, the particle sizes increase with the increase of pH value, the most suitable pH value is 1.
Cu(NO3)2and (NH4)2Mo2O7 were used to fabricate Mo/Cu composite nanopowders by sol-gel technique. The influences of heat treatment process, solution pH value and the addition agent on the particle size were investigated by DTA-TG, XRD and TEM. The results show that under certain heat treatment temperature, the quantity of the addition agent influences the grain size of nanoparticle. When the quantity ratio of addition agent is 0.5, we can get fine nanoparticles with small grain size and homogeneous granularity. The particle sizes are varied under various solution acidities. When pH values change form 1 to 4, the particle sizes increase with the increase of pH value, the most suitable pH value is 1.
2005, 34(6):998-1001.
Abstract:
The discrimination between CuCr25 and CuCr50 alloys for the cathode spot craters with peak currents of 10 A and 80 A has been studied in this paper. The microstructure analysis showed that the CuCr alloys has an important effect on the discrimination, in which the size of Cr phase plays an main role in effecting the moving direction and distribution of cathode spot craters. It can well be explained why the chopping current of CuCr25 is less than CuCr50 by the direct measurements of chopping current and arc lifetime by oscillograph. All above useful conclusions will provide powerful supports on decreasing chopping current by minimizing the size of Cr phase for CuCr alloys.
The discrimination between CuCr25 and CuCr50 alloys for the cathode spot craters with peak currents of 10 A and 80 A has been studied in this paper. The microstructure analysis showed that the CuCr alloys has an important effect on the discrimination, in which the size of Cr phase plays an main role in effecting the moving direction and distribution of cathode spot craters. It can well be explained why the chopping current of CuCr25 is less than CuCr50 by the direct measurements of chopping current and arc lifetime by oscillograph. All above useful conclusions will provide powerful supports on decreasing chopping current by minimizing the size of Cr phase for CuCr alloys.
2005, 34(6):1002-1004.
Abstract:
用X射线衍射法研究测定了热推制成形和退火后的环形纯钛管表面的残余应力及分布特点；用OM观察了退火后的试样金相组织：测定了不同退火温度下，钛管抗拉性能，并用SEM观察了拉伸断口形貌。研究结果发现：热推制加工后的环形钛管变形不均匀，存在残余应力；经700℃～750℃再结晶退火后，可有效的降低残余应力；再结晶退火后环形管获得细小等轴晶粒，使抗拉塑性增高。
用X射线衍射法研究测定了热推制成形和退火后的环形纯钛管表面的残余应力及分布特点；用OM观察了退火后的试样金相组织：测定了不同退火温度下，钛管抗拉性能，并用SEM观察了拉伸断口形貌。研究结果发现：热推制加工后的环形钛管变形不均匀，存在残余应力；经700℃～750℃再结晶退火后，可有效的降低残余应力；再结晶退火后环形管获得细小等轴晶粒，使抗拉塑性增高。
2005, 34(6):1005-1008.
Abstract:
研究了巯基活性炭在盐酸介质中对金、铂、钯和铊的吸附能力。该法具有吸附速度快、吸附容量大、在一定条件下，普通金属不被吸附的特点，可用于分离富集各类矿物中微量贵金属。吸附后巯基活性炭低温灰化，与缓冲剂混合发射光谱法同时测定金、铂、钯和铊，选择锆作内标线，直接压样于杯形的石墨电极中，该方法简便、快速、准确。对测定条件、干扰因素进行了研究，从而建立测定金、铂、钯和铊的新方法。金、铂、钯和铊的分析线分别为312.3nm，306．5nm，311．4nm和313．1nm，内标线选择为310．7nm的锆，金、铂、钯和铊的线性范围(原子百分数)分别为0～0．20％，0～0．40％，0～0．20％和0～0．40％。金、铂、钯和铊的检测限分别0．01％，0．003％，0．003％和0．001％。用于样品的测定获得满意结果。
研究了巯基活性炭在盐酸介质中对金、铂、钯和铊的吸附能力。该法具有吸附速度快、吸附容量大、在一定条件下，普通金属不被吸附的特点，可用于分离富集各类矿物中微量贵金属。吸附后巯基活性炭低温灰化，与缓冲剂混合发射光谱法同时测定金、铂、钯和铊，选择锆作内标线，直接压样于杯形的石墨电极中，该方法简便、快速、准确。对测定条件、干扰因素进行了研究，从而建立测定金、铂、钯和铊的新方法。金、铂、钯和铊的分析线分别为312.3nm，306．5nm，311．4nm和313．1nm，内标线选择为310．7nm的锆，金、铂、钯和铊的线性范围(原子百分数)分别为0～0．20％，0～0．40％，0～0．20％和0～0．40％。金、铂、钯和铊的检测限分别0．01％，0．003％，0．003％和0．001％。用于样品的测定获得满意结果。
