Volume 33,Issue 1,2004 Table of Contents
2004, 33(1):1-4.
Abstract:
The rechargeable lithium ion battery has been extensively used in mobile communication and portable instruments due to its many advantages, such as high volumetric and gravimetric energy density, long cycle life, low self-discharge rate. In addition, it is the promising candidate as the power source for electric vehicles. The first generation of negative electrode materials was pure lithium metal; the second was carbon. Nowadays extensive research is focusing on lithium alloys. In this paper, the properties of lithium metal and carbon are summarized and the development of lithium alloys is reviewed.
The rechargeable lithium ion battery has been extensively used in mobile communication and portable instruments due to its many advantages, such as high volumetric and gravimetric energy density, long cycle life, low self-discharge rate. In addition, it is the promising candidate as the power source for electric vehicles. The first generation of negative electrode materials was pure lithium metal; the second was carbon. Nowadays extensive research is focusing on lithium alloys. In this paper, the properties of lithium metal and carbon are summarized and the development of lithium alloys is reviewed.
2004, 33(1):5-10.
Abstract:
Since the discovery of ordered mesoporous silica materials (MCM41) in 1992, mesoporous materials have become a hot spot in many research fields, such as catalysis, separation, adsorption, optics, electronics, etc. This paper reviews the synthesis, classification, formation mechanism, morphology control and application of mesoporous materials. Nowadays, various shaped mesostructured materials (spheres, rods, plates, spirals, ropes etc.) have been synthesized using the sol-gel, self-assembly, micro-emulsion, reverse micellar and sonochemical method etc. The mesoporous materials can be classified into silica-based and non-silica materials. Siliceous ordered mesoporous materials have been well investigated. On the other hand, less attention has been directed towards non-siliceous materials, although these could have more widespread applications. Several formation mechanisms have been proposed, including the liquid crystal templating (LCT) approach and the cooperative organization mechanism. We have prepared novel mesoporous TiO2 powders and thin films by the sonochemical and reversed mecellar methods. Their photocatalytic activity is significantly higher than those of ordinary TiO2 powders and thin films.
Since the discovery of ordered mesoporous silica materials (MCM41) in 1992, mesoporous materials have become a hot spot in many research fields, such as catalysis, separation, adsorption, optics, electronics, etc. This paper reviews the synthesis, classification, formation mechanism, morphology control and application of mesoporous materials. Nowadays, various shaped mesostructured materials (spheres, rods, plates, spirals, ropes etc.) have been synthesized using the sol-gel, self-assembly, micro-emulsion, reverse micellar and sonochemical method etc. The mesoporous materials can be classified into silica-based and non-silica materials. Siliceous ordered mesoporous materials have been well investigated. On the other hand, less attention has been directed towards non-siliceous materials, although these could have more widespread applications. Several formation mechanisms have been proposed, including the liquid crystal templating (LCT) approach and the cooperative organization mechanism. We have prepared novel mesoporous TiO2 powders and thin films by the sonochemical and reversed mecellar methods. Their photocatalytic activity is significantly higher than those of ordinary TiO2 powders and thin films.
2004, 33(1):11-14.
Abstract:
The current research status of tungsten-copper composites used at high temperature in China had been expounded, which involves the fabricating technique, high temperature strength, burning erosive resistance, thermo-shock resistance and dimensional stability, etc. The properties of material have been developing as the sintering-melting method had been used. The high temperature strength was objected to the strength of tungsten skeleton. The thermo-shock resistance was subjected to the Cu-content and its well-distributed in material after melting-penetrating. And through the technologys improving, the burning erosive resistance and dimensional stability in the course of sintering had well been developed.
The current research status of tungsten-copper composites used at high temperature in China had been expounded, which involves the fabricating technique, high temperature strength, burning erosive resistance, thermo-shock resistance and dimensional stability, etc. The properties of material have been developing as the sintering-melting method had been used. The high temperature strength was objected to the strength of tungsten skeleton. The thermo-shock resistance was subjected to the Cu-content and its well-distributed in material after melting-penetrating. And through the technologys improving, the burning erosive resistance and dimensional stability in the course of sintering had well been developed.
2004, 33(1):15-18.
Abstract:
Five LaNi5-type hydrogen storage alloys were prepared. Their electrodes?discharge capacity,high rate charge-discharge ability, temperature effect,crystal structure and cycling stability were investigated. The XRD results indicated that alloys examined in this work seem to be of single phase with the hexagonal CaCu5-type crystal structure. After 400 charge-discharge cycles, the same crystal structure remained, for some of oxides, for instance, Mm(OH)3 and La(OH)3;The composition of stannum or silicon stabilizes the cycle life and improves the high rate charge-discharge abilities of their electrodes;The electrochemical capacity of sample (Ml0.90Nd0.10)Ni3.60Co0.50Mn0.40Al0.18Si0.42 is above 290.72 mAh.g-1, with capacity preserving being above 70% after 400 charge-discharge cycles. Its 5C rate charge efficiency is higher than 95%,and 5C rate discharge efficiency higher than 90%. It also performs well at various operating temperatures.
Five LaNi5-type hydrogen storage alloys were prepared. Their electrodes?discharge capacity,high rate charge-discharge ability, temperature effect,crystal structure and cycling stability were investigated. The XRD results indicated that alloys examined in this work seem to be of single phase with the hexagonal CaCu5-type crystal structure. After 400 charge-discharge cycles, the same crystal structure remained, for some of oxides, for instance, Mm(OH)3 and La(OH)3;The composition of stannum or silicon stabilizes the cycle life and improves the high rate charge-discharge abilities of their electrodes;The electrochemical capacity of sample (Ml0.90Nd0.10)Ni3.60Co0.50Mn0.40Al0.18Si0.42 is above 290.72 mAh.g-1, with capacity preserving being above 70% after 400 charge-discharge cycles. Its 5C rate charge efficiency is higher than 95%,and 5C rate discharge efficiency higher than 90%. It also performs well at various operating temperatures.
Zhang Yumei
,
Wang Qintao
,
Zhao Yimin
,
Guo Tianwen
,
Li Zuochen
,
J.-C. Hornez
,
H.F.Hildebrand
,
M.Tralsnel
2004, 33(1):19-22.
Abstract:
Titanium and its alloys are recognized as biocompatible materials for use in medical devices. During the last few years a new generation of Ti alloys has been created with the aim of removing vanadium as an alloying element (e.g. in Ti-6Al-4V), the potential cytotoxic effect of which has been demonstrated in several investigations. The scope of the present work is to establish the corrosion behaviors of some new titanium alloys(Ti75 alloy, TiZr alloy)in 0.9% NaCl electrolyte and in particular under biological conditions. The results showed that the new alloys generally exhibit good electrochemical behaviors in rest potential (Er), corrosion potential (Ec) and passive current density (Ip). A remarkable difference is encountered with respect to the electrolyte RPMI alone induces a favorable Ec and an increased Ip, whereas the presence of cells decreases the Ip and the Ec with respect to 0.9% NaCl and RPMI. So RPMI with or without cells is a more relevant physical electrolyte than 0.9% NaCl. The new titanium alloys show by their electrochemical behavior some advantages as compared to Ti6Al4V.
Titanium and its alloys are recognized as biocompatible materials for use in medical devices. During the last few years a new generation of Ti alloys has been created with the aim of removing vanadium as an alloying element (e.g. in Ti-6Al-4V), the potential cytotoxic effect of which has been demonstrated in several investigations. The scope of the present work is to establish the corrosion behaviors of some new titanium alloys(Ti75 alloy, TiZr alloy)in 0.9% NaCl electrolyte and in particular under biological conditions. The results showed that the new alloys generally exhibit good electrochemical behaviors in rest potential (Er), corrosion potential (Ec) and passive current density (Ip). A remarkable difference is encountered with respect to the electrolyte RPMI alone induces a favorable Ec and an increased Ip, whereas the presence of cells decreases the Ip and the Ec with respect to 0.9% NaCl and RPMI. So RPMI with or without cells is a more relevant physical electrolyte than 0.9% NaCl. The new titanium alloys show by their electrochemical behavior some advantages as compared to Ti6Al4V.
2004, 33(1):23-26.
Abstract:
研究了不同热处理工艺对M963合金显微组织和拉伸性能的影响。结果表明，经1210℃，4h空冷固溶处理后，合金的强度升高，但塑性降低，尤其是在高温(900℃)时塑性降低幅度更大：固溶处理后再进行850℃，16h炉冷时效，强度进一步提高，高温塑性获得恢复，但室温塑性进一步降低。扫描电镜观察发现：合金在l210℃，4h空冷固溶处理过程中，初生MC碳化物发生转变，并在晶界和枝晶间析出M6C碳化物；在固溶处理后的空冷过程中，从γ溶体基体中析出细小γ相；经850℃，16h低温时效后，γ充分析出并长大。断口形貌分析表明不同热处理状态的合金，其断裂机制不同。根据位错与强化相之间的相互作用理论讨论了这种热处理工艺对室温和高温拉伸性能的不同影响规律。
研究了不同热处理工艺对M963合金显微组织和拉伸性能的影响。结果表明，经1210℃，4h空冷固溶处理后，合金的强度升高，但塑性降低，尤其是在高温(900℃)时塑性降低幅度更大：固溶处理后再进行850℃，16h炉冷时效，强度进一步提高，高温塑性获得恢复，但室温塑性进一步降低。扫描电镜观察发现：合金在l210℃，4h空冷固溶处理过程中，初生MC碳化物发生转变，并在晶界和枝晶间析出M6C碳化物；在固溶处理后的空冷过程中，从γ溶体基体中析出细小γ相；经850℃，16h低温时效后，γ充分析出并长大。断口形貌分析表明不同热处理状态的合金，其断裂机制不同。根据位错与强化相之间的相互作用理论讨论了这种热处理工艺对室温和高温拉伸性能的不同影响规律。
2004, 33(1):27-30.
Abstract:
在交流条件硅酸钠溶液中利用微等离子体氧化技术合成了陶瓷涂层。通过XRD，EPMA分析了所得陶瓷涂层在不同层面上的相组成、微观结构及元素分布。由陶瓷涂层截面的背散射图看出陶瓷涂层较致密、与基体结合强度高。XRD分析结果显示，陶瓷涂层的最外层由莫来石及γ-Al2O3相组成，随着向陶瓷涂层内部的移动，莫来石的含量逐渐减少，α-Al2O3，γ-A12O3相的含量逐渐提高，而且陶瓷涂层的颜色由白色逐渐变为黑色。硅元素在陶瓷涂层的外侧及陶瓷涂层与基体的交界处陶瓷涂层一侧含量较多，在陶瓷涂层中间含量少。而陶瓷涂层的硬度变化也出现了中间高，两侧低的分布情况。
在交流条件硅酸钠溶液中利用微等离子体氧化技术合成了陶瓷涂层。通过XRD，EPMA分析了所得陶瓷涂层在不同层面上的相组成、微观结构及元素分布。由陶瓷涂层截面的背散射图看出陶瓷涂层较致密、与基体结合强度高。XRD分析结果显示，陶瓷涂层的最外层由莫来石及γ-Al2O3相组成，随着向陶瓷涂层内部的移动，莫来石的含量逐渐减少，α-Al2O3，γ-A12O3相的含量逐渐提高，而且陶瓷涂层的颜色由白色逐渐变为黑色。硅元素在陶瓷涂层的外侧及陶瓷涂层与基体的交界处陶瓷涂层一侧含量较多，在陶瓷涂层中间含量少。而陶瓷涂层的硬度变化也出现了中间高，两侧低的分布情况。
2004, 33(1):31-34.
Abstract:
Titanium anodes were sol-gel coated with RuO2+SnO+TiO2 containing various amounts of SnO2 by brushing, sintering and annealing. The effect of SnO2 on the microstructure; morphology and particle size of the RuO2+TiO2+SnO2/Ti coatings was examined by XRD, DTA and TEM. It was concluded that the crystal size of the coatings, which was on the scale of nanometers, was sharply reduced with increasing SnO2 content. At same time, it was shown that the coatings, which consisted mainly of a solid solution- (Ru,Sn,Ti)O2 , would remain stable and monophase during increases of the SnO2 content and the annealing temperature. The morphology of the RuO2+TiO2+SnO2 crystals in the coating was equiaxial, due largely to the presence of the SnO2.
Titanium anodes were sol-gel coated with RuO2+SnO+TiO2 containing various amounts of SnO2 by brushing, sintering and annealing. The effect of SnO2 on the microstructure; morphology and particle size of the RuO2+TiO2+SnO2/Ti coatings was examined by XRD, DTA and TEM. It was concluded that the crystal size of the coatings, which was on the scale of nanometers, was sharply reduced with increasing SnO2 content. At same time, it was shown that the coatings, which consisted mainly of a solid solution- (Ru,Sn,Ti)O2 , would remain stable and monophase during increases of the SnO2 content and the annealing temperature. The morphology of the RuO2+TiO2+SnO2 crystals in the coating was equiaxial, due largely to the presence of the SnO2.
2004, 33(1):35-39.
Abstract:
A model was established for high strength aluminum alloys to describe the elastic/plastic stress and strain at the crack tip fields and the effects of second phase particles with various size scales on tensile ductility. The model presents a multi-element nonlinear relation between the fatigue crack growth rate and the characteristics of constituents, dispersoids, and precipitates within the alloys. Qualitative agreement between experimental and theoretical results is obtained for the fatigue crack growth rates of 2024 Al alloy. Moreover, an optimum scheme to reduce the fatigue crack growth rates and maintain alloy strength could be approached by application of the model.
A model was established for high strength aluminum alloys to describe the elastic/plastic stress and strain at the crack tip fields and the effects of second phase particles with various size scales on tensile ductility. The model presents a multi-element nonlinear relation between the fatigue crack growth rate and the characteristics of constituents, dispersoids, and precipitates within the alloys. Qualitative agreement between experimental and theoretical results is obtained for the fatigue crack growth rates of 2024 Al alloy. Moreover, an optimum scheme to reduce the fatigue crack growth rates and maintain alloy strength could be approached by application of the model.
2004, 33(1):40-42.
Abstract:
The effect of Al2O3 on the mechanical properties and microstructure of a Ti3SiC2/ Al2O3 composite fabricated by SPS(Spark Plasma Sintering)was studied in detail. The results show that the presence of the Al2O3 improves the hardness of the Ti3SiC2 up to 10.28 GPa. While at the same time increasing the strength and fracture toughness. On the other hand, slight decreases in flexural strength and fracture toughness were observed with Al2O3 additions higher than 10vol%, as a result of agglomeration of Al2O3 particles in the composite.
The effect of Al2O3 on the mechanical properties and microstructure of a Ti3SiC2/ Al2O3 composite fabricated by SPS(Spark Plasma Sintering)was studied in detail. The results show that the presence of the Al2O3 improves the hardness of the Ti3SiC2 up to 10.28 GPa. While at the same time increasing the strength and fracture toughness. On the other hand, slight decreases in flexural strength and fracture toughness were observed with Al2O3 additions higher than 10vol%, as a result of agglomeration of Al2O3 particles in the composite.
2004, 33(1):43-46.
Abstract:
The mechanical properties, especially the elongation of the powder metallurgy (PM) Ti alloy (Ti12LC, Ti8LC) at room temperature are less than optimal due to oxygen contamination and porosity. The results of this work show that the addition of the rare earth element Nd to the PM Ti alloy resulted in improved tensile strength and elongation. The alloy containing 0.8wt% Nd has a tensile strength of 1 080MPa and an elongation of 14%. Almost the same as those of wrought material, while the processing cost was lower. The rare earth element served to scavenge oxygen from the powder surfaces thereby purifying the particle interfaces. This together with a decrease of the oxygen content of Ti substrate plus the formation of Nd oxides resulted in mechanical properties of PM Ti alloy.
The mechanical properties, especially the elongation of the powder metallurgy (PM) Ti alloy (Ti12LC, Ti8LC) at room temperature are less than optimal due to oxygen contamination and porosity. The results of this work show that the addition of the rare earth element Nd to the PM Ti alloy resulted in improved tensile strength and elongation. The alloy containing 0.8wt% Nd has a tensile strength of 1 080MPa and an elongation of 14%. Almost the same as those of wrought material, while the processing cost was lower. The rare earth element served to scavenge oxygen from the powder surfaces thereby purifying the particle interfaces. This together with a decrease of the oxygen content of Ti substrate plus the formation of Nd oxides resulted in mechanical properties of PM Ti alloy.
2004, 33(1):47-50.
Abstract:
Mg(OH)2 samples with acicular or fibrous crystallizing morphology were successfully prepared by one-step reaction method under hydrothermal conditions and indexed as a hexagonal crystal system based on the results of XRD and TEM. Moreover, based on the theoretical model of anionic coordination polyhedron growth units, the growth mechanism and growth habit of the Mg(OH)2 crystals under hydrothermal conditions were first investigated in depth. It was concluded, after calculating the stability energy of the growth unit of Mg(OH)2 crystalline, that the growth direction of the growth unit of the Mg(OH)2 crystal tends to favor a one-dimensional direction, parallel to the basic layer of the Mg(OH)2 crystal. Accordingly, we propose that natural brucite with fibred crystallizing morphology was formed under hydrothermal conditions in the earth thousands years ago.
Mg(OH)2 samples with acicular or fibrous crystallizing morphology were successfully prepared by one-step reaction method under hydrothermal conditions and indexed as a hexagonal crystal system based on the results of XRD and TEM. Moreover, based on the theoretical model of anionic coordination polyhedron growth units, the growth mechanism and growth habit of the Mg(OH)2 crystals under hydrothermal conditions were first investigated in depth. It was concluded, after calculating the stability energy of the growth unit of Mg(OH)2 crystalline, that the growth direction of the growth unit of the Mg(OH)2 crystal tends to favor a one-dimensional direction, parallel to the basic layer of the Mg(OH)2 crystal. Accordingly, we propose that natural brucite with fibred crystallizing morphology was formed under hydrothermal conditions in the earth thousands years ago.
2004, 33(1):51-54.
Abstract:
采用悬浮熔炼法制备了Fe-Sm-Si热电合金材料,并研究了其电学输运特性。实验表明:在Fe1-xSmxSi2合金中,Sm为n型掺杂元素,Sm轻掺杂时,试样仍为p型,随着Sm量的增加,试样的Seebeck系数和功率因子都降低;Sm含量x 0.4的高Sm硅化物试样为n型,其中,热电性能最好的试样成分为Fe0.6Sm0.4Si2,其电阻率在10-5W穖数量级,而Seebeck系数仍达到80 mV稫-1左右。其机理被认为是由于Sm的4f层电子的贡献。
采用悬浮熔炼法制备了Fe-Sm-Si热电合金材料,并研究了其电学输运特性。实验表明:在Fe1-xSmxSi2合金中,Sm为n型掺杂元素,Sm轻掺杂时,试样仍为p型,随着Sm量的增加,试样的Seebeck系数和功率因子都降低;Sm含量x 0.4的高Sm硅化物试样为n型,其中,热电性能最好的试样成分为Fe0.6Sm0.4Si2,其电阻率在10-5W穖数量级,而Seebeck系数仍达到80 mV稫-1左右。其机理被认为是由于Sm的4f层电子的贡献。
2004, 33(1):55-58.
Abstract:
采用磁控溅射方法在Ni基单晶高温合金上沉积NiCrAlY涂层，研究了真空热处理及高温氧化过程中，NiCrAlY涂层／Ni基单晶合金界面显微结构的变化及元素扩散行为。结果表明，原始涂层成分分布比较均匀，各元素分布在涂层／基体界面呈陡然变化。真空热处理时，涂层与基体间发生互扩散，NiCrAlY涂层的显微结构和相结构发生变化：涂层／基体界面区出现互扩散层(内、外扩散层)；出现γ-Ni3Al和α-Cr两新相，导致涂层局部区域富Cr。1000℃氧化200h后，涂层／基体界面区的互扩散层增厚，并且在其下的基体中出现扩散影响层。Ta在涂层中扩散时，置换了部分γ-Ni3Al相中的Al，导致γ相的晶格常数α0增大。
采用磁控溅射方法在Ni基单晶高温合金上沉积NiCrAlY涂层，研究了真空热处理及高温氧化过程中，NiCrAlY涂层／Ni基单晶合金界面显微结构的变化及元素扩散行为。结果表明，原始涂层成分分布比较均匀，各元素分布在涂层／基体界面呈陡然变化。真空热处理时，涂层与基体间发生互扩散，NiCrAlY涂层的显微结构和相结构发生变化：涂层／基体界面区出现互扩散层(内、外扩散层)；出现γ-Ni3Al和α-Cr两新相，导致涂层局部区域富Cr。1000℃氧化200h后，涂层／基体界面区的互扩散层增厚，并且在其下的基体中出现扩散影响层。Ta在涂层中扩散时，置换了部分γ-Ni3Al相中的Al，导致γ相的晶格常数α0增大。
2004, 33(1):59-62.
Abstract:
The effect of intermetallic compound TiAl additions on the combustion synthesis of Ti3AlC2 powder from Ti, Al and C as starting powders has been studied. The experimental results show that the main phase of the combustion product is TiC with very small amount of Ti3AlC2, if the molar ratio of Ti, Al, C is equal to 3:1:2. However, Ti3AlC2 become the main phase with a small amount of TiC if a small amount of TiAl is added to the starting mixtures without changing the overall stoichiometry. The fraction of Ti3AlC2 increases with increasing additions of TiAl to the starting mixtures. The above experimental phenomena were explained through thermodynamic and kinetic analysis.
The effect of intermetallic compound TiAl additions on the combustion synthesis of Ti3AlC2 powder from Ti, Al and C as starting powders has been studied. The experimental results show that the main phase of the combustion product is TiC with very small amount of Ti3AlC2, if the molar ratio of Ti, Al, C is equal to 3:1:2. However, Ti3AlC2 become the main phase with a small amount of TiC if a small amount of TiAl is added to the starting mixtures without changing the overall stoichiometry. The fraction of Ti3AlC2 increases with increasing additions of TiAl to the starting mixtures. The above experimental phenomena were explained through thermodynamic and kinetic analysis.
2004, 33(1):63-66.
Abstract:
Ordered-structure multilayer thin films were prepared on quartz substrates by the electrostatic self-assembly method. The UV-Vis-NIR spectrophotometer and the atomic force microscope (AFM) were used to characterize the films. The results indicated that order structure nanoporous TiO2 thin films showed high photocatalytic activity, and that the photocatalytic activity of heat-treated thin film was higher than that of UV irradiated film.
Ordered-structure multilayer thin films were prepared on quartz substrates by the electrostatic self-assembly method. The UV-Vis-NIR spectrophotometer and the atomic force microscope (AFM) were used to characterize the films. The results indicated that order structure nanoporous TiO2 thin films showed high photocatalytic activity, and that the photocatalytic activity of heat-treated thin film was higher than that of UV irradiated film.
2004, 33(1):67-69.
Abstract:
Two superconducting Nb-47wt%Ti composites with island shaped Ti5wt%Nb artificial pinning centers (APC) have been made. The Ti5wt%Nb volume fractions in the composites are 10% and 20% respectively. The bulk flux pinning force curves of the APC NbTi composites at 4.2K have been studied. The results show that as the pin size is reduced Fpmax increases, and moves to higher magnetic fields. The behavior of the bulk flux pinning force curves of the Ti5wt%Nb APC NbTi composites is better than that of Nb APC NbTi composites, in that Fpmax occurs at a higher magnetic field.
Two superconducting Nb-47wt%Ti composites with island shaped Ti5wt%Nb artificial pinning centers (APC) have been made. The Ti5wt%Nb volume fractions in the composites are 10% and 20% respectively. The bulk flux pinning force curves of the APC NbTi composites at 4.2K have been studied. The results show that as the pin size is reduced Fpmax increases, and moves to higher magnetic fields. The behavior of the bulk flux pinning force curves of the Ti5wt%Nb APC NbTi composites is better than that of Nb APC NbTi composites, in that Fpmax occurs at a higher magnetic field.
2004, 33(1):70-74.
Abstract:
Nanocrystalline W powder and tungsten based W-Ni-Fe prealloyed powders were prepared by high-energy ball milling. The influences of: (i) milling media including cemented carbide balls (CCB) and tungsten alloy balls (TAB), (ii) rotational speed, (iii) ratio of ball to powder, and (iv) grinding time on powder characteristics were studied. The grain size, lattice deformation and morphology, of the component of particles after milled were analyzed by means of XRD, EDX and TEM. The results showed that nanocrystalline powders with size of 10nm to 80nm could be synthesized by high-energy ball milling. The percentage of nanocrystalline particles in the powders is up to 80%. The overall properties of the nanocrystalline powders prepared using the TAB milling medium was better than those prepared by CCB milling. During milling the morphology of the nanocrystalline powder evolves from spherical to granular.
Nanocrystalline W powder and tungsten based W-Ni-Fe prealloyed powders were prepared by high-energy ball milling. The influences of: (i) milling media including cemented carbide balls (CCB) and tungsten alloy balls (TAB), (ii) rotational speed, (iii) ratio of ball to powder, and (iv) grinding time on powder characteristics were studied. The grain size, lattice deformation and morphology, of the component of particles after milled were analyzed by means of XRD, EDX and TEM. The results showed that nanocrystalline powders with size of 10nm to 80nm could be synthesized by high-energy ball milling. The percentage of nanocrystalline particles in the powders is up to 80%. The overall properties of the nanocrystalline powders prepared using the TAB milling medium was better than those prepared by CCB milling. During milling the morphology of the nanocrystalline powder evolves from spherical to granular.
19 Preparation of Pr10.5(FeCoZr)83.5B6 Bonded Magnets with High Coercivity and Low Rare-Earth Content
2004, 33(1):75-78.
Abstract:
采用部分过快淬加后续晶化退火处理的方法，研究了快淬速度和晶化工艺对低稀土含量Pr0.5(FeCoZr)83.5B6粘结磁体磁性能的影响。通过实验对比发现，以26m／s速度快淬出的条屑由微晶和非晶组织组成，在700℃经10min的晶化处理，可获得最佳磁性能，用3．25％(质量分数)环氧树脂粘结的磁体磁性能为：Br=0．673T，Hci=610kA／m，Hcb=379kA／m，(BH)rn=71kJ/m^3，具有较高的内禀矫顽力和综合磁性能。
采用部分过快淬加后续晶化退火处理的方法，研究了快淬速度和晶化工艺对低稀土含量Pr0.5(FeCoZr)83.5B6粘结磁体磁性能的影响。通过实验对比发现，以26m／s速度快淬出的条屑由微晶和非晶组织组成，在700℃经10min的晶化处理，可获得最佳磁性能，用3．25％(质量分数)环氧树脂粘结的磁体磁性能为：Br=0．673T，Hci=610kA／m，Hcb=379kA／m，(BH)rn=71kJ/m^3，具有较高的内禀矫顽力和综合磁性能。
2004, 33(1):79-82.
Abstract:
结合溶胶．凝胶法和水热法的优点，将溶胶处理引入水热法中，采用改进的水热法在低温条件下合成了纯钙钛矿结构钛酸钡纳米粉，并与水热法合成产物进行了适当的比较。通过XRD，TEM，X射线荧光光谱(XRF)，微分扫描式量热法(DSC)以及热重分析(TGA)分析了BaTiO3粉的结构和组成，并初步探讨了溶胶处理的作用。结果表明，采用乙酰丙酮改性的钛酸四丁酯作为Ti源，可有效降低BaTiO3纳米粉的水热合成温度；与常用水热法相比，采用改进的水热法合成BaTiO3纳米粉的温度更低。溶胶处理过程有利于水热合成温度的降低。
结合溶胶．凝胶法和水热法的优点，将溶胶处理引入水热法中，采用改进的水热法在低温条件下合成了纯钙钛矿结构钛酸钡纳米粉，并与水热法合成产物进行了适当的比较。通过XRD，TEM，X射线荧光光谱(XRF)，微分扫描式量热法(DSC)以及热重分析(TGA)分析了BaTiO3粉的结构和组成，并初步探讨了溶胶处理的作用。结果表明，采用乙酰丙酮改性的钛酸四丁酯作为Ti源，可有效降低BaTiO3纳米粉的水热合成温度；与常用水热法相比，采用改进的水热法合成BaTiO3纳米粉的温度更低。溶胶处理过程有利于水热合成温度的降低。
2004, 33(1):83-86.
Abstract:
采用电沉积水热合成法和高温煅烧相结合的方法，制备了生物陶瓷涂层，研究了涂层与基体间过渡层的物相组成和界面结合强度。用X射线(XRD)、扫描电镜(SEM)和粘接拉伸法进行分析。结果表明：水热合成后，界面结合强度较低，为7．04MPa。在空气中煅烧，700℃以下时，界面出现极薄TiO2层，同时随着煅烧温度的升高，界面结合强度提高；800℃以上时，由于厚而疏松过渡层TiN的出现，界面结合强度反而下降。为获取对骨生长有利的HAP β-Ca3(PO4)2双相结构，且界面结合强度高的涂层材料，将原始试样用NaOH碱液处理并进行电沉积水热合成，在氩气中900℃煅烧后，过渡层为薄且致密的TiO2层，界面结合强度高达22．39MPa。
采用电沉积水热合成法和高温煅烧相结合的方法，制备了生物陶瓷涂层，研究了涂层与基体间过渡层的物相组成和界面结合强度。用X射线(XRD)、扫描电镜(SEM)和粘接拉伸法进行分析。结果表明：水热合成后，界面结合强度较低，为7．04MPa。在空气中煅烧，700℃以下时，界面出现极薄TiO2层，同时随着煅烧温度的升高，界面结合强度提高；800℃以上时，由于厚而疏松过渡层TiN的出现，界面结合强度反而下降。为获取对骨生长有利的HAP β-Ca3(PO4)2双相结构，且界面结合强度高的涂层材料，将原始试样用NaOH碱液处理并进行电沉积水热合成，在氩气中900℃煅烧后，过渡层为薄且致密的TiO2层，界面结合强度高达22．39MPa。
2004, 33(1):87-90.
Abstract:
Based on boundary uncertainty theory, the service life of a powder metallurgy processed (PM) turbine disk has been analyzed. First, the general formulations are presented. The effects of the boundary uncertainty variables on PM disk life response are formulated mathematically by Taylor expansion based on the boundary uncertainty descriptions. In order to present the lifetime results (output), to a specified uncertainty a critical relative maximum deviation has been presented for the required bounds of the (input) variables. Using experimental data for the PW alloy FGH95, the boundary life of a FGH95 turbine disk has been derived. The two key bounded variables among all possible ones are chosen as an example, and the accepted jointed bounds for the two variables have been calculated to satisfy a specified fatigue life of more than 4 000 cycle number. The example shows the advantage of the boundary uncertainty than the classic probability method, and can be applied to a simple sample.
Based on boundary uncertainty theory, the service life of a powder metallurgy processed (PM) turbine disk has been analyzed. First, the general formulations are presented. The effects of the boundary uncertainty variables on PM disk life response are formulated mathematically by Taylor expansion based on the boundary uncertainty descriptions. In order to present the lifetime results (output), to a specified uncertainty a critical relative maximum deviation has been presented for the required bounds of the (input) variables. Using experimental data for the PW alloy FGH95, the boundary life of a FGH95 turbine disk has been derived. The two key bounded variables among all possible ones are chosen as an example, and the accepted jointed bounds for the two variables have been calculated to satisfy a specified fatigue life of more than 4 000 cycle number. The example shows the advantage of the boundary uncertainty than the classic probability method, and can be applied to a simple sample.
2004, 33(1):91-95.
Abstract:
使用共沉淀法合成了完全固溶的Al2Mo3-xWxO12系列粉体材料，用热机械分析(TMA)压缩法测定其热膨胀系数，发现Al2Mo3-xWxO12的单斜-正交转变温度随x增加而下降；通过调整材料的组成，可以控制材料的热膨胀系数，并有望在此类材料中获得近零或负热膨胀材料。但是由于其结构的各向异性，多晶陶瓷内部存在的微裂纹使热膨胀曲线出现较大的滞后环。
使用共沉淀法合成了完全固溶的Al2Mo3-xWxO12系列粉体材料，用热机械分析(TMA)压缩法测定其热膨胀系数，发现Al2Mo3-xWxO12的单斜-正交转变温度随x增加而下降；通过调整材料的组成，可以控制材料的热膨胀系数，并有望在此类材料中获得近零或负热膨胀材料。但是由于其结构的各向异性，多晶陶瓷内部存在的微裂纹使热膨胀曲线出现较大的滞后环。
2004, 33(1):96-100.
Abstract:
A newly developed Ag5wt%C electrical contact material was fabricated using the technique of high-energy in conjunction with reductant liquid spraying chemical coating and powder metallurgy. Compared with its conventional counterparts made from traditional blending and extrusion, the new contact material has excellent physical and mechanical properties. Contact-erosion experiments were performed using an ASTM Contact Material Automatic Measuring Device. The experimental results indicated that the arc erosion resistance of the newly developed Ag5wt%C material was more than 40% higher than that of the conventionally blended counterpart. The microstructures of the AgC coating powder and the sintered-pressed sample were characterized by SEM and metallographic microscopy. The surface morphologies of the two types of Ag5wt%C contact after breaking arc melting were examined by SEM together with EDS. It was found that the melted Ag particles produced by arc thermal shock become spherical and adhered to the matrix, thereby decreasing the splattering loss of Ag. The wettability and interfacial strength between silver and graphite were much improved as a result of using the new technique. The newly developed AgC may substitute for those counterparts made from extrusion or blending as a new electrical contact material.
A newly developed Ag5wt%C electrical contact material was fabricated using the technique of high-energy in conjunction with reductant liquid spraying chemical coating and powder metallurgy. Compared with its conventional counterparts made from traditional blending and extrusion, the new contact material has excellent physical and mechanical properties. Contact-erosion experiments were performed using an ASTM Contact Material Automatic Measuring Device. The experimental results indicated that the arc erosion resistance of the newly developed Ag5wt%C material was more than 40% higher than that of the conventionally blended counterpart. The microstructures of the AgC coating powder and the sintered-pressed sample were characterized by SEM and metallographic microscopy. The surface morphologies of the two types of Ag5wt%C contact after breaking arc melting were examined by SEM together with EDS. It was found that the melted Ag particles produced by arc thermal shock become spherical and adhered to the matrix, thereby decreasing the splattering loss of Ag. The wettability and interfacial strength between silver and graphite were much improved as a result of using the new technique. The newly developed AgC may substitute for those counterparts made from extrusion or blending as a new electrical contact material.
2004, 33(1):101-104.
Abstract:
为得到C／SiC复合材料的强连接，利用三维编织碳纤维增韧碳化硅(C／SiC)复合材料在制备过程中残留的孔隙，采用Ni合金作为中间层在1300℃保温45min、真空条件下对三维C／SiC复合材料用液相渗透连接方法进行了在线连接，所施压力为20MPa。利用扫描电镜(SEM)及能谱初步分析了连接情况，结果表明Ni合金与C／SiC复合材料有较好的润湿性，续沉积SiC后试样三点弯曲强度可达σ拉=252．1MPa，σ压=260．3MPa。
为得到C／SiC复合材料的强连接，利用三维编织碳纤维增韧碳化硅(C／SiC)复合材料在制备过程中残留的孔隙，采用Ni合金作为中间层在1300℃保温45min、真空条件下对三维C／SiC复合材料用液相渗透连接方法进行了在线连接，所施压力为20MPa。利用扫描电镜(SEM)及能谱初步分析了连接情况，结果表明Ni合金与C／SiC复合材料有较好的润湿性，续沉积SiC后试样三点弯曲强度可达σ拉=252．1MPa，σ压=260．3MPa。
2004, 33(1):105-108.
Abstract:
采用溶胶-凝胶法制备出尺寸小于100nm的SnO2纳米粉体，并采用XRD，TEM等手段对其进行表征，进而将粉体制成旁热式气敏元件测试其气敏性能。结果表明，粉体的尺寸随热处理温度的变化较大，所制气敏元件具有优良的气敏特性，响应恢复时间可以保证其正常使用，但功耗较大，灵敏度较高，尤其对甲烷有较高的灵敏度。
采用溶胶-凝胶法制备出尺寸小于100nm的SnO2纳米粉体，并采用XRD，TEM等手段对其进行表征，进而将粉体制成旁热式气敏元件测试其气敏性能。结果表明，粉体的尺寸随热处理温度的变化较大，所制气敏元件具有优良的气敏特性，响应恢复时间可以保证其正常使用，但功耗较大，灵敏度较高，尤其对甲烷有较高的灵敏度。
2004, 33(1):109-112.
Abstract:
Cu and Ni films coated on one or both sides of stainless steel substrates were produced by brush plating and electroplating techniques, respectively. The elastic moduli of Cu and Ni films with various thickness on substrates were determined using three-point bending tests. The results showed that the elastic moduli of Cu and Ni films were almost independence of film thickness and approximately the same as those of corresponding bulk materials.
Cu and Ni films coated on one or both sides of stainless steel substrates were produced by brush plating and electroplating techniques, respectively. The elastic moduli of Cu and Ni films with various thickness on substrates were determined using three-point bending tests. The results showed that the elastic moduli of Cu and Ni films were almost independence of film thickness and approximately the same as those of corresponding bulk materials.
