Volume 35,Issue 4,2006 Table of Contents
2006, 35(4):505-509.
Abstract:
Possessing multiple energy levels, unique 4f electron transition ability and optical properties, rare earth elements can improve efficiently the activity of TiO2 photocatalysts by doping or preparing compound semiconductors. Furthermore, novel photocatalysts have been secured with RE elements. Based on relative documents, the application of rare earth elements in photocatalysts is reviewed in this paper, including RE modified TiO2 photocatalysts and non-TiO2 photocatalysts. The roles of RE elements and its mechanism, as well as the focus and outlook of the research of RE-containing photocatalysts were deeply discussed.
Possessing multiple energy levels, unique 4f electron transition ability and optical properties, rare earth elements can improve efficiently the activity of TiO2 photocatalysts by doping or preparing compound semiconductors. Furthermore, novel photocatalysts have been secured with RE elements. Based on relative documents, the application of rare earth elements in photocatalysts is reviewed in this paper, including RE modified TiO2 photocatalysts and non-TiO2 photocatalysts. The roles of RE elements and its mechanism, as well as the focus and outlook of the research of RE-containing photocatalysts were deeply discussed.
2006, 35(4):510-515.
Abstract:
Bulk metallic glasses have unique mechanical properties, including high strengths (~2 GPa), large elastic limits (2%~3%), and excellent resistance to corrosion, but the poor room temperature ductility restricts its applications as structural materials. In this paper, the room temperature brittleness of bulk metallic glasses was discussed based on the deformation and fracture mechanism, and the progress in improving room temperature ductility by introducing second phase in the amorphous matrix was summarized.
Bulk metallic glasses have unique mechanical properties, including high strengths (~2 GPa), large elastic limits (2%~3%), and excellent resistance to corrosion, but the poor room temperature ductility restricts its applications as structural materials. In this paper, the room temperature brittleness of bulk metallic glasses was discussed based on the deformation and fracture mechanism, and the progress in improving room temperature ductility by introducing second phase in the amorphous matrix was summarized.
2006, 35(4):516-520.
Abstract:
REO-ZrO2 mixed oxides serve as a key material in the electrolyte of oxygen sensor and promoter of three-way catalyst (TWC), which are widely applied in the purification of automotive exhaust. The principles of the applications were expounded; meanwhile the adulteration of RE ions into ZrO2 applied in oxygen sensor was introduced. The research of CeO2-ZrO2 mixed oxides applied as promoter of TWC was summarized, and the further application of REO-ZrO2 composite in the automotive exhaust decontamination was prospected.
REO-ZrO2 mixed oxides serve as a key material in the electrolyte of oxygen sensor and promoter of three-way catalyst (TWC), which are widely applied in the purification of automotive exhaust. The principles of the applications were expounded; meanwhile the adulteration of RE ions into ZrO2 applied in oxygen sensor was introduced. The research of CeO2-ZrO2 mixed oxides applied as promoter of TWC was summarized, and the further application of REO-ZrO2 composite in the automotive exhaust decontamination was prospected.
2006, 35(4):521-527.
Abstract:
Three-dimensional (3D) C/SiC composites with a CVD SiC coatings and a PyC interphase were prepared by low-pressure chemical vapor deposition method. The interphase was annealed and changed in thickness. Dualism, certainty and randomicity, in the evolution of C/SiC composites under complicated environments were investigated. The results show that residual strength and its fluctuation are important when evaluating environmental adaptability and reliability. The interphase and coatings are the key microstructural units most sensitive to oxidizing environments. The three parameters to be considered, in order of importance, are temperature, atmosphere and stress sensitivity. The most significant atmosphere is oxygen, followed by water and salt, while the most important stress parameters are fatigue/creep interaction, creep and fatigue. Stress promotes degradation of the composites due to opening of cracks in the coatings. An oxide film on the coatings is best to seal these cracks, and water can accelerate this sealing. However, a fatigue/creep interaction stress causes sealing failure, and then the environment including oxygen, water, fatigue and creep is the worse one of all. For the composites to be self-adaptable, the PyC thickness should be optimum for increasing annealing effect, and the coatings should be oxidized at a moderate rate for increasing resistance to oxidation. The temperature and the partial pressure of oxidizing gases control the moderate rate.
Three-dimensional (3D) C/SiC composites with a CVD SiC coatings and a PyC interphase were prepared by low-pressure chemical vapor deposition method. The interphase was annealed and changed in thickness. Dualism, certainty and randomicity, in the evolution of C/SiC composites under complicated environments were investigated. The results show that residual strength and its fluctuation are important when evaluating environmental adaptability and reliability. The interphase and coatings are the key microstructural units most sensitive to oxidizing environments. The three parameters to be considered, in order of importance, are temperature, atmosphere and stress sensitivity. The most significant atmosphere is oxygen, followed by water and salt, while the most important stress parameters are fatigue/creep interaction, creep and fatigue. Stress promotes degradation of the composites due to opening of cracks in the coatings. An oxide film on the coatings is best to seal these cracks, and water can accelerate this sealing. However, a fatigue/creep interaction stress causes sealing failure, and then the environment including oxygen, water, fatigue and creep is the worse one of all. For the composites to be self-adaptable, the PyC thickness should be optimum for increasing annealing effect, and the coatings should be oxidized at a moderate rate for increasing resistance to oxidation. The temperature and the partial pressure of oxidizing gases control the moderate rate.
2006, 35(4):528-532.
Abstract:
采用电化学测试技术研究了在PBS人工模拟体液中纤维蛋白原对CoCrNiMo和CoCrNiW合金腐蚀行为的影响.结果表明,CoCrNi合金具有良好的耐孔蚀性能,其钝化电位区较宽,且电位扫描曲线滞后环面积小.用EDX能谱对试样进行分析发现,在CoCrNi合金表面形成了Co,Cr,Ni,Mo,W等的钝性金属氧化物膜.纤维蛋白原在CoCrNi合金表面发生了吸附,且吸附的蛋白质分布不连续.用紫外吸收法测量CoCrNiMo和CoCrNiW对纤维蛋白原的吸附量分别为10.628 μg/cm2和9.561μg/cm2.含有纤维蛋白原的PBS人工模拟体液中CoCrNi合金的腐蚀行为可用吸附理论解释.其反应步骤为(1)氧原子吸附在合金能量较高的活性点上,形成较为稳定的吸附氧化膜;(2)纤维蛋白原扩散到合金表面以形成络合物的形式与氧原子构成竞争吸附;(3)形成的金属络合物向溶液产生电化学迁移,破坏了合金表面的钝性氧化膜,使icorr值显著增大,加剧了合金的腐蚀.
采用电化学测试技术研究了在PBS人工模拟体液中纤维蛋白原对CoCrNiMo和CoCrNiW合金腐蚀行为的影响.结果表明,CoCrNi合金具有良好的耐孔蚀性能,其钝化电位区较宽,且电位扫描曲线滞后环面积小.用EDX能谱对试样进行分析发现,在CoCrNi合金表面形成了Co,Cr,Ni,Mo,W等的钝性金属氧化物膜.纤维蛋白原在CoCrNi合金表面发生了吸附,且吸附的蛋白质分布不连续.用紫外吸收法测量CoCrNiMo和CoCrNiW对纤维蛋白原的吸附量分别为10.628 μg/cm2和9.561μg/cm2.含有纤维蛋白原的PBS人工模拟体液中CoCrNi合金的腐蚀行为可用吸附理论解释.其反应步骤为(1)氧原子吸附在合金能量较高的活性点上,形成较为稳定的吸附氧化膜;(2)纤维蛋白原扩散到合金表面以形成络合物的形式与氧原子构成竞争吸附;(3)形成的金属络合物向溶液产生电化学迁移,破坏了合金表面的钝性氧化膜,使icorr值显著增大,加剧了合金的腐蚀.
2006, 35(4):533-537.
Abstract:
The XRD, SEM, isothermal oxidation-weight loss and non-isothermal TG-DTG were used to study the properties of SiC coatings/ 3-D braided carbon fiber(composite fiber) prepared by in-situ reaction method. The results show that coatings is coated symmetrically and combine well with every fiber of 3-D braids in proper reaction conditions, the oxidation resistance of composite fiber increase with the increase of SiC coatings thickness. The oxidation resistant properties and mechanism of composite fiber were studied also.
The XRD, SEM, isothermal oxidation-weight loss and non-isothermal TG-DTG were used to study the properties of SiC coatings/ 3-D braided carbon fiber(composite fiber) prepared by in-situ reaction method. The results show that coatings is coated symmetrically and combine well with every fiber of 3-D braids in proper reaction conditions, the oxidation resistance of composite fiber increase with the increase of SiC coatings thickness. The oxidation resistant properties and mechanism of composite fiber were studied also.
2006, 35(4):538-541.
Abstract:
The plastic deformation during quenching is first induced by tension stress, and then alternative occurrence of tension and compression stress induce plastic deformation. The tension stress may induce compression stress. Compression stress occur in the surface, which is different from conventional view that only tension stress occurs in the surface. The thermal stress during quenching is mainly determined by temperature difference other than temperature. Compression stress occur and develop in the relative high temperature zone, and tension stress occur and develop in the relative low temperature zone. It is the source of thermal stresses, plastic deformation, residual stresses when quenching or quickly heating. The corner and edge models for thermal stress during quenching are established in this paper, and the corner effect, which go with the recession of, temperature grads, thermal stresses and plastic deformation after the first plastic deformation is induced by tension stress, is proposed in the course of quenching.
The plastic deformation during quenching is first induced by tension stress, and then alternative occurrence of tension and compression stress induce plastic deformation. The tension stress may induce compression stress. Compression stress occur in the surface, which is different from conventional view that only tension stress occurs in the surface. The thermal stress during quenching is mainly determined by temperature difference other than temperature. Compression stress occur and develop in the relative high temperature zone, and tension stress occur and develop in the relative low temperature zone. It is the source of thermal stresses, plastic deformation, residual stresses when quenching or quickly heating. The corner and edge models for thermal stress during quenching are established in this paper, and the corner effect, which go with the recession of, temperature grads, thermal stresses and plastic deformation after the first plastic deformation is induced by tension stress, is proposed in the course of quenching.
2006, 35(4):542-545.
Abstract:
用脉冲激光沉积法在斜切(001)SrTiO3单晶基片上生长了c轴取向的YBa2Cu3O7-δ超导薄膜,在斜切(001)LaAlO3单晶基片上生长了Ba0.1Sr0.9TiO3/YBa2Cu3O7-δ双层薄膜,并用扫描电镜和透射电镜对薄膜组织进行了表征。结果表明,在1°~3°斜切的SrTiO3基片上生长的YBa2Cu3O7-δ薄膜,呈现台阶流动(stepflow)到三维岛状生长的转变;而6°~15°斜切基片上生长的YBa2Cu3O7-δ薄膜为完全台阶流动生长。在1.2°斜切的LaAlO3基片上原位制备了良好异质外延生长的Ba0.1Sr0.9TiO3/YBa2Cu3O7-δ双层薄膜。在77K,1MHz频率和±30V直流偏压下,测定了其电容-电压特性,确定其介电常数、可调谐性和品质因数分别为1200,60%和133。表明该Ba0.1Sr0.9TiO3薄膜可应用于在液氮温度下工作的可调谐微波器件。
用脉冲激光沉积法在斜切(001)SrTiO3单晶基片上生长了c轴取向的YBa2Cu3O7-δ超导薄膜,在斜切(001)LaAlO3单晶基片上生长了Ba0.1Sr0.9TiO3/YBa2Cu3O7-δ双层薄膜,并用扫描电镜和透射电镜对薄膜组织进行了表征。结果表明,在1°~3°斜切的SrTiO3基片上生长的YBa2Cu3O7-δ薄膜,呈现台阶流动(stepflow)到三维岛状生长的转变;而6°~15°斜切基片上生长的YBa2Cu3O7-δ薄膜为完全台阶流动生长。在1.2°斜切的LaAlO3基片上原位制备了良好异质外延生长的Ba0.1Sr0.9TiO3/YBa2Cu3O7-δ双层薄膜。在77K,1MHz频率和±30V直流偏压下,测定了其电容-电压特性,确定其介电常数、可调谐性和品质因数分别为1200,60%和133。表明该Ba0.1Sr0.9TiO3薄膜可应用于在液氮温度下工作的可调谐微波器件。
2006, 35(4):546-549.
Abstract:
以乙酰丙酮铂为前驱体,采用金属有机化合物化学气相沉积(MOCVD)法在石英及YSZ基体上制备Pt/C薄膜,研究了Pt/C薄膜的结构和电化学性能。沉积过程中通入一定量的氧气可以大幅降低Pt/C薄膜中的含C量,含C较高的Pt/C薄膜的XRD谱线低而宽,具有非晶态衍射特征。在500℃测量温度下,以Pt/C薄膜为电极的YSZ氧气浓差电池的电动势及电流输出高于传统的Pt电极。
以乙酰丙酮铂为前驱体,采用金属有机化合物化学气相沉积(MOCVD)法在石英及YSZ基体上制备Pt/C薄膜,研究了Pt/C薄膜的结构和电化学性能。沉积过程中通入一定量的氧气可以大幅降低Pt/C薄膜中的含C量,含C较高的Pt/C薄膜的XRD谱线低而宽,具有非晶态衍射特征。在500℃测量温度下,以Pt/C薄膜为电极的YSZ氧气浓差电池的电动势及电流输出高于传统的Pt电极。
2006, 35(4):550-553.
Abstract:
研究了微量Sc对Al-Cu-Li-Zr合金微观组织和拉伸性能的影响。结果表明:添加0.1%Sc(质量分数,下同)能消除铸态合金的枝晶组织,细化合金的晶粒。合金铸锭在随后的均匀化和热加工加热过程中,析出细小、弥散的次生Al3Sc质点,这种质点强烈地钉扎合金中的位错和亚晶界,从而有效地抑制合金的再结晶,具有亚结构强化和直接析出强化作用。加入微量Sc后,Al-Cu-Li-Zr合金的强度大大提高,并且合金的塑性也得到明显改善。
研究了微量Sc对Al-Cu-Li-Zr合金微观组织和拉伸性能的影响。结果表明:添加0.1%Sc(质量分数,下同)能消除铸态合金的枝晶组织,细化合金的晶粒。合金铸锭在随后的均匀化和热加工加热过程中,析出细小、弥散的次生Al3Sc质点,这种质点强烈地钉扎合金中的位错和亚晶界,从而有效地抑制合金的再结晶,具有亚结构强化和直接析出强化作用。加入微量Sc后,Al-Cu-Li-Zr合金的强度大大提高,并且合金的塑性也得到明显改善。
2006, 35(4):554-558.
Abstract:
The reactive Gibbs free energies, the reactive formation enthalpies and adiabatic temperatures concerning the preparation ofMoSi2-WSi2 composites using elemental powders of Mo, W and Si by the thermal explosion mode of SHS have been theoreticallycalculated and investigated by experiments. XRD, SEM and EDAX have analyzed the phase compositions and micro-area chemicalanalyses of the products. The results show that the reactive formation enthalpies of MoSi2 and WSi2 are biggest, 234.645 kJ/mol and195.670 kJ/mol respectively, when the reactions take place at 1685 K (the melting point of Si). And when the initial temperature is 1685 Kthe products of all systems have fused completely. Pure MoSi2-WSi2 composites are fabricated by the thermal explosion mode of SHS, andMoSi2-WSi2 exists as solid solution of (Mox,W1-x)Si2 while the chemical elements of every grain are not uniform.
The reactive Gibbs free energies, the reactive formation enthalpies and adiabatic temperatures concerning the preparation ofMoSi2-WSi2 composites using elemental powders of Mo, W and Si by the thermal explosion mode of SHS have been theoreticallycalculated and investigated by experiments. XRD, SEM and EDAX have analyzed the phase compositions and micro-area chemicalanalyses of the products. The results show that the reactive formation enthalpies of MoSi2 and WSi2 are biggest, 234.645 kJ/mol and195.670 kJ/mol respectively, when the reactions take place at 1685 K (the melting point of Si). And when the initial temperature is 1685 Kthe products of all systems have fused completely. Pure MoSi2-WSi2 composites are fabricated by the thermal explosion mode of SHS, andMoSi2-WSi2 exists as solid solution of (Mox,W1-x)Si2 while the chemical elements of every grain are not uniform.
Niu Rongmei
,
Zhang Guojun
,
Sun Jun
,
Wei Jianfeng
,
Sun Yuanjun
,
Zhao Baohua
,
Yang Liuxiao
,
Ma Baoping
2006, 35(4):559-561.
Abstract:
借助扫描电镜(SEM)原位拉伸观察了纯钼退火态纤维状组织断裂过程中裂纹萌生与扩展的动态变化过程,对其微观断裂特征进行了研究。结果表明:加载初期,裂纹在与最大主应力平面成45°的位置萌生,随后逐渐张开并钝化;加载中期,新的裂纹在钝化的主裂纹前方某处萌生。随着载荷增加,裂纹呈“Z”字形相互连接;加载末期,裂纹失稳扩展,试样断裂。在裂尖应力场作用下,裂纹扩展遵循钝化-萌生-钝化的循环方式。纯钼试样断裂后,沿厚度方向有明显的颈缩,断口表面呈薄层状纤维撕裂,并伴有剪切唇和韧窝的出现,呈延性断裂特征。
借助扫描电镜(SEM)原位拉伸观察了纯钼退火态纤维状组织断裂过程中裂纹萌生与扩展的动态变化过程,对其微观断裂特征进行了研究。结果表明:加载初期,裂纹在与最大主应力平面成45°的位置萌生,随后逐渐张开并钝化;加载中期,新的裂纹在钝化的主裂纹前方某处萌生。随着载荷增加,裂纹呈“Z”字形相互连接;加载末期,裂纹失稳扩展,试样断裂。在裂尖应力场作用下,裂纹扩展遵循钝化-萌生-钝化的循环方式。纯钼试样断裂后,沿厚度方向有明显的颈缩,断口表面呈薄层状纤维撕裂,并伴有剪切唇和韧窝的出现,呈延性断裂特征。
2006, 35(4):562-566.
Abstract:
根据改进分析型嵌入原子模型(MAEAM),通过计算钒的总能量随温度的变化关系确定其熔点为2160±10K,与实验值(2175K)一致。运用分子动力学方法(MD)从原子面密度函数、面结构因子、面径向分布函数三个方面研究了V(111)晶面的预熔现象和熔化情况,发现V(111)面在800K左右开始出现预熔。
根据改进分析型嵌入原子模型(MAEAM),通过计算钒的总能量随温度的变化关系确定其熔点为2160±10K,与实验值(2175K)一致。运用分子动力学方法(MD)从原子面密度函数、面结构因子、面径向分布函数三个方面研究了V(111)晶面的预熔现象和熔化情况,发现V(111)面在800K左右开始出现预熔。
14 Microstructural Evolution during Self-Propagating High-Temperature Synthesis of Ni3Al Intermetallic
2006, 35(4):567-572.
Abstract:
In order to investigate the microstructural evolution of Ni3Al intermetallic from Al and Ni powders during self-propagating high-temperature synthesis (SHS), a combustion front quenching method (CFQM) was used for extinguishing the propagating combustion wave. The microstructures on the quenched sample were observed with scanning electron microscope (SEM) and analyzed with energy dispersive spectrometry (EDS), the temperature of the combustion reaction was tested, and the phase constituent of the synthesized product was inspected by X-ray diffraction (XRD). The results show that the combustion reaction started with melting of the Al particles, and the melting results in partial dissolution of the Ni particles. With interdiffusing between Ni and Al atoms, reaction-diffusing layer of Ni3Al forms on the surface of the undissolving Ni particles and become thicker and thicker continually. Also, the reaction is incomplete, and this is because the coarser Ni and Al powders are used in the present work.
In order to investigate the microstructural evolution of Ni3Al intermetallic from Al and Ni powders during self-propagating high-temperature synthesis (SHS), a combustion front quenching method (CFQM) was used for extinguishing the propagating combustion wave. The microstructures on the quenched sample were observed with scanning electron microscope (SEM) and analyzed with energy dispersive spectrometry (EDS), the temperature of the combustion reaction was tested, and the phase constituent of the synthesized product was inspected by X-ray diffraction (XRD). The results show that the combustion reaction started with melting of the Al particles, and the melting results in partial dissolution of the Ni particles. With interdiffusing between Ni and Al atoms, reaction-diffusing layer of Ni3Al forms on the surface of the undissolving Ni particles and become thicker and thicker continually. Also, the reaction is incomplete, and this is because the coarser Ni and Al powders are used in the present work.
2006, 35(4):573-576.
Abstract:
The effects of Ni-P coatings on the electrochemical properties of La0.67Mg0.33Ni2.5Co0.5 hydrogen storage alloy electrode was studied. The kinetic properties of the alloy electrode were evaluated. The results show that the cycling stability of the electrode is improved. The Ni-P coated powder electrode is better than bare electrode in exchange current density I0, Limiting current density I1, high rate dischargeability and hydrogen diffusion coefficient D. It is found that the surface microencapsulation is ineffective in prohibiting disintegration, main reason for which is probably ascribed to the larger expansion of the La0.67Mg0.33Ni2.5Co0.5 hydrogen storage alloy hydride.
The effects of Ni-P coatings on the electrochemical properties of La0.67Mg0.33Ni2.5Co0.5 hydrogen storage alloy electrode was studied. The kinetic properties of the alloy electrode were evaluated. The results show that the cycling stability of the electrode is improved. The Ni-P coated powder electrode is better than bare electrode in exchange current density I0, Limiting current density I1, high rate dischargeability and hydrogen diffusion coefficient D. It is found that the surface microencapsulation is ineffective in prohibiting disintegration, main reason for which is probably ascribed to the larger expansion of the La0.67Mg0.33Ni2.5Co0.5 hydrogen storage alloy hydride.
2006, 35(4):577-580.
Abstract:
用压痕法测量EB-PVD热障涂层的弹性模量及断裂韧性。发现热障涂层的Vickers显微硬度和弹性模量随施压载荷增大而减小,当载荷为2.94N时,显微硬度和弹性模量接近稳态值,分别为6.3GPa和172GPa;断裂韧性平均值约为1.81MPa·m1/2。压痕法测得陶瓷层断裂韧性数据波动较大,其主要原因是陶瓷层显微结构不均匀,使压痕裂纹在涂层不同局部区域所遇到的扩展阻力不同。
用压痕法测量EB-PVD热障涂层的弹性模量及断裂韧性。发现热障涂层的Vickers显微硬度和弹性模量随施压载荷增大而减小,当载荷为2.94N时,显微硬度和弹性模量接近稳态值,分别为6.3GPa和172GPa;断裂韧性平均值约为1.81MPa·m1/2。压痕法测得陶瓷层断裂韧性数据波动较大,其主要原因是陶瓷层显微结构不均匀,使压痕裂纹在涂层不同局部区域所遇到的扩展阻力不同。
2006, 35(4):581-584.
Abstract:
Five ternary complexes have been synthesized from europium with aromatic carboxylic acid(p-methylbenzoic acid, methoxybenzoic acid, m-chlorobenzoic acid, benzoic acid, p-hydroxylbenzoic acid) and acrylamide; and also characterized by means of elemental analysis, thermal analysis, FT-IR spectra and UV spectra. Fluorescence spectra show five ternary complexes have nice luminescent properties, the sequence of ability that the aromatic carboxylic acids transfer light energy to europium ion is as follows: benzoic acid > p-methylbenzoic acid > methoxybenzoic acid > m-chlorobenzoic acid > p-hydroxylbenzoic acid. At the same time, the ternary europium complexes containing a reactive ligand acrylamide will possibly have potential application on the fabrication of bonding-type europium polymer luminescent materials.
Five ternary complexes have been synthesized from europium with aromatic carboxylic acid(p-methylbenzoic acid, methoxybenzoic acid, m-chlorobenzoic acid, benzoic acid, p-hydroxylbenzoic acid) and acrylamide; and also characterized by means of elemental analysis, thermal analysis, FT-IR spectra and UV spectra. Fluorescence spectra show five ternary complexes have nice luminescent properties, the sequence of ability that the aromatic carboxylic acids transfer light energy to europium ion is as follows: benzoic acid > p-methylbenzoic acid > methoxybenzoic acid > m-chlorobenzoic acid > p-hydroxylbenzoic acid. At the same time, the ternary europium complexes containing a reactive ligand acrylamide will possibly have potential application on the fabrication of bonding-type europium polymer luminescent materials.
2006, 35(4):585-588.
Abstract:
In this work, 1,4-dioxane (cyclic ether ) was used to pre-treat the surface of Li electrode in order to passivate Li electrode and improve its interfacial stability and charge/discharge cycleability. It Is found that 1,4-dioxane can polymerize and form a good SEI passivating layer on the surface of Li electrode. This layer is able to enhance the interfacial stability of Li electrode without depress its kinetic behavior. Further measurements of charge/discharge efficiency of treated/bare Li electrodes and cycleability of Li metal cells fabricated with different Li anodes show that the Li electrode treated with 1,4-dioxane has higher charge/discharge efficiency compared with that of bare Li electrode, and the cell with such anode has better discharging performance and cycle life.
In this work, 1,4-dioxane (cyclic ether ) was used to pre-treat the surface of Li electrode in order to passivate Li electrode and improve its interfacial stability and charge/discharge cycleability. It Is found that 1,4-dioxane can polymerize and form a good SEI passivating layer on the surface of Li electrode. This layer is able to enhance the interfacial stability of Li electrode without depress its kinetic behavior. Further measurements of charge/discharge efficiency of treated/bare Li electrodes and cycleability of Li metal cells fabricated with different Li anodes show that the Li electrode treated with 1,4-dioxane has higher charge/discharge efficiency compared with that of bare Li electrode, and the cell with such anode has better discharging performance and cycle life.
2006, 35(4):589-592.
Abstract:
Besides improvement of the magnetic refrigerant materials for development of magnetic refrigeration, an excellent magnetic field source is same important. Based on the hollow cylindrical flux source, a permanent magnetic circuit is designed for rotating room-temperature refrigerator. And after optimization by Ansys software, a permanent magnetic circuit, in which the average magnetic induction strength at the center of the working gap is up to 1.75 T, is got. Relative to the unoptimization magnetic circuit by Ansys software, the average magnetic induction strength in the center gap raise by 20%, and the magnetic circuit weight descend by 21%.
Besides improvement of the magnetic refrigerant materials for development of magnetic refrigeration, an excellent magnetic field source is same important. Based on the hollow cylindrical flux source, a permanent magnetic circuit is designed for rotating room-temperature refrigerator. And after optimization by Ansys software, a permanent magnetic circuit, in which the average magnetic induction strength at the center of the working gap is up to 1.75 T, is got. Relative to the unoptimization magnetic circuit by Ansys software, the average magnetic induction strength in the center gap raise by 20%, and the magnetic circuit weight descend by 21%.
2006, 35(4):593-595.
Abstract:
ZrSiN film was selected as diffusion barrier and sputtered on polished titanium substrate with RF reactive magnetron sputtering. XRD, XPS and SEM results reveal that the ZrSiN diffusion barrier is a nano-composite that consists of nano-crystallite ZrN and amorphous-like SiNx phase. The results also show that in the surface of Ti substrate without ZrSiN diffusion barrier, there is Ti oxides, however, in the surface of Ti substrate with ZrSiN diffusion barrier, there is not Ti oxides and does only Zr, Si, N and O. This proves that ZrSiN diffusion barrier protect the Ti substrate against oxidation. The three-point bending test results prove that ZrSiN diffusion barrier significantly improves the bonding strength between Ti substrate and porcelain. The ZrSiN diffusion barrier with high Si content results in higher adhesion strength of the Ti/porcelain. This indicates that amorphous Si-N phase of ZrSiN diffusion barrier improves its barrier property.
ZrSiN film was selected as diffusion barrier and sputtered on polished titanium substrate with RF reactive magnetron sputtering. XRD, XPS and SEM results reveal that the ZrSiN diffusion barrier is a nano-composite that consists of nano-crystallite ZrN and amorphous-like SiNx phase. The results also show that in the surface of Ti substrate without ZrSiN diffusion barrier, there is Ti oxides, however, in the surface of Ti substrate with ZrSiN diffusion barrier, there is not Ti oxides and does only Zr, Si, N and O. This proves that ZrSiN diffusion barrier protect the Ti substrate against oxidation. The three-point bending test results prove that ZrSiN diffusion barrier significantly improves the bonding strength between Ti substrate and porcelain. The ZrSiN diffusion barrier with high Si content results in higher adhesion strength of the Ti/porcelain. This indicates that amorphous Si-N phase of ZrSiN diffusion barrier improves its barrier property.
2006, 35(4):596-599.
Abstract:
一氧化铌(NbO)具有与金属相近的导电能力,作为阳极赋能时,与铝、钽、铌等阀金属一样,能在阳极表面形成介电性能优良的无定型氧化膜。研究了真空碳还原Nb2O5制备NbO的原理、工艺条件以及一氧化铌粉末的理化性能和电性能等,参照GB/T3137-1995关于电容器用钽粉电性能测试方法,经实测,一氧化铌粉末具有比电容105120μF·V/g,损耗11.2%,漏电流2.5×10–4μA/μF·V,表明其湿式电性能已达到甚至优于相应的高比容钽粉的水平;沿用钽电容器生产工艺,探索性地进行了小批量以NbO为阳极的电解电容器生产,其成品合格率达到77%。
一氧化铌(NbO)具有与金属相近的导电能力,作为阳极赋能时,与铝、钽、铌等阀金属一样,能在阳极表面形成介电性能优良的无定型氧化膜。研究了真空碳还原Nb2O5制备NbO的原理、工艺条件以及一氧化铌粉末的理化性能和电性能等,参照GB/T3137-1995关于电容器用钽粉电性能测试方法,经实测,一氧化铌粉末具有比电容105120μF·V/g,损耗11.2%,漏电流2.5×10–4μA/μF·V,表明其湿式电性能已达到甚至优于相应的高比容钽粉的水平;沿用钽电容器生产工艺,探索性地进行了小批量以NbO为阳极的电解电容器生产,其成品合格率达到77%。
2006, 35(4):600-604.
Abstract:
利用放电等离子烧结(SPS)技术,原位制备了Ti2AlC/TiAl复合材料,研究了多步热处理对Ti2AlC/TiAl显微组织与力学性能的影响.结果表明,通过多步热处理,Ti2AlC/TiAl的力学性能得到明显改善.其中在1390℃热处理时,弯曲强度达到957.9 MPa,断裂韧性达到20.73 MPa·m1/2.通过多步热处理,可以得到双态组织和晶粒更为细小均匀的近y组织的TiAl基体,复合材料的断裂模式转变为穿晶解理断裂.在热处理过程中,Ti2AlC能够显著抑制TiAl基体中y晶粒和α2/y层片晶团的长大,并且在一定程度上,阻碍α2/y层片晶团的形成.
利用放电等离子烧结(SPS)技术,原位制备了Ti2AlC/TiAl复合材料,研究了多步热处理对Ti2AlC/TiAl显微组织与力学性能的影响.结果表明,通过多步热处理,Ti2AlC/TiAl的力学性能得到明显改善.其中在1390℃热处理时,弯曲强度达到957.9 MPa,断裂韧性达到20.73 MPa·m1/2.通过多步热处理,可以得到双态组织和晶粒更为细小均匀的近y组织的TiAl基体,复合材料的断裂模式转变为穿晶解理断裂.在热处理过程中,Ti2AlC能够显著抑制TiAl基体中y晶粒和α2/y层片晶团的长大,并且在一定程度上,阻碍α2/y层片晶团的形成.
2006, 35(4):605-608.
Abstract:
Zr41.2Ti13.8Ni10Cu12.5Be22.5 bulk amorphous alloy was prepared by arc-melting and rapid casting into a copper mould. The rapid viscous flow of the bulk amorphous alloy was studied by the energy storage and the energy fast releasing. It is shown that the rapid viscous flow deformation, forming, welding can be carried out in the supercooled liquid region. And micro gear and same materials jointing is prepared successfully. There is no crystallization phase in the forming part and welding seam area. The tensile strength of the welded seam area is the same as that of the bulk amorphous matrix materials.
Zr41.2Ti13.8Ni10Cu12.5Be22.5 bulk amorphous alloy was prepared by arc-melting and rapid casting into a copper mould. The rapid viscous flow of the bulk amorphous alloy was studied by the energy storage and the energy fast releasing. It is shown that the rapid viscous flow deformation, forming, welding can be carried out in the supercooled liquid region. And micro gear and same materials jointing is prepared successfully. There is no crystallization phase in the forming part and welding seam area. The tensile strength of the welded seam area is the same as that of the bulk amorphous matrix materials.
2006, 35(4):609-612.
Abstract:
在氢气氛中机械球磨铸态Nd12Fe82B6(at%)合金,利用机械力驱动使之发生歧化反应,随后进行真空脱氢-再结合处理,获得纳米晶合金粉末材料.采用差示扫描量热法(DSC),分析了歧化态合金粉末的脱氢-再结合行为.利用X射线衍射(XRD),扫描电镜(SEM),及透射电镜(TEM)等测试方法,研究了球磨及脱氢-再结合过程中合金粉末的相变与微观组织.结果表明在0.2 MPa氢气氛中球磨20 h,可使Nd12Fe82B6合金完全歧化,形成晶粒尺寸约为8 nm的Nd2H5,Fe2B和α-Fe的纳米歧化组织,并且粉末颗粒细化到0.5μm～1.0 μm.在760℃,30 min的条件下进行真空脱氢-再结合处理,获得了平均晶粒尺寸约为30 nm的Nd2Fe14B/α-Fe纳米复相Nd12Fe82B6合金粉末.
在氢气氛中机械球磨铸态Nd12Fe82B6(at%)合金,利用机械力驱动使之发生歧化反应,随后进行真空脱氢-再结合处理,获得纳米晶合金粉末材料.采用差示扫描量热法(DSC),分析了歧化态合金粉末的脱氢-再结合行为.利用X射线衍射(XRD),扫描电镜(SEM),及透射电镜(TEM)等测试方法,研究了球磨及脱氢-再结合过程中合金粉末的相变与微观组织.结果表明在0.2 MPa氢气氛中球磨20 h,可使Nd12Fe82B6合金完全歧化,形成晶粒尺寸约为8 nm的Nd2H5,Fe2B和α-Fe的纳米歧化组织,并且粉末颗粒细化到0.5μm～1.0 μm.在760℃,30 min的条件下进行真空脱氢-再结合处理,获得了平均晶粒尺寸约为30 nm的Nd2Fe14B/α-Fe纳米复相Nd12Fe82B6合金粉末.
2006, 35(4):613-616.
Abstract:
The wetting behaviors of the Sn-8Zn-3Bi-(0~5)In alloys on Cu substrate were tested by an area-of-spread method. The spreading areas of these alloys increase with the addition of In before In content reaches 0.5wt%, which indicates small addition of In can improve the wettability of Sn-8Zn-3Bi based alloys. Bubble's largest pressure method was applied to measure the surface tensions of the Sn-8Zn-3Bi-(0~1.5)In melts. Adding 0.5wt% In into the foundry alloy, the surface tension of the alloy is lower than that of the other alloys. But more addition of In causes degradation of the surface tension. Wetting balance method was used to evaluate the wetting forces of these solders on Cu substrates. With addition of 0.5wt% In, wetting force reaches the maximum, which results from decrease of the solder/Cu interfacial tension.
The wetting behaviors of the Sn-8Zn-3Bi-(0~5)In alloys on Cu substrate were tested by an area-of-spread method. The spreading areas of these alloys increase with the addition of In before In content reaches 0.5wt%, which indicates small addition of In can improve the wettability of Sn-8Zn-3Bi based alloys. Bubble's largest pressure method was applied to measure the surface tensions of the Sn-8Zn-3Bi-(0~1.5)In melts. Adding 0.5wt% In into the foundry alloy, the surface tension of the alloy is lower than that of the other alloys. But more addition of In causes degradation of the surface tension. Wetting balance method was used to evaluate the wetting forces of these solders on Cu substrates. With addition of 0.5wt% In, wetting force reaches the maximum, which results from decrease of the solder/Cu interfacial tension.
2006, 35(4):617-620.
Abstract:
Raw powder of ZnFe2O4 and V-doped ZnFe2O4 were obtained by the citrate pyrolysis, and the effect of V doping on phase constituents, resistance-temperature behavior and gas-sensing properties to benzene and its derivatives were studied. The results demonstrate that as the increase of V doping amount, raw powder is the spinel structure, the resistance of ZnFe2O4 sensor decrease, and the sensitivity to benzene and its derivatives at higher operating temperature increase.
Raw powder of ZnFe2O4 and V-doped ZnFe2O4 were obtained by the citrate pyrolysis, and the effect of V doping on phase constituents, resistance-temperature behavior and gas-sensing properties to benzene and its derivatives were studied. The results demonstrate that as the increase of V doping amount, raw powder is the spinel structure, the resistance of ZnFe2O4 sensor decrease, and the sensitivity to benzene and its derivatives at higher operating temperature increase.
2006, 35(4):621-624.
Abstract:
According to the heat transfer analysis of Airslip mold, an analytical model was presented to study the solidification shell thickness and the critical solidification shell thickness. The theoretical analysis and experimental results indicate that the product of solidification shell thickness and the casting rate is a constant, when the casting rate increases, the solidification shell thickness decreases and the billet surface is better, the variation of the casting rate brings the fluctuation of solidification shell thickness and therefore deteriorates the billet surface. It is also shown that the product of billet diameter and the casting rate is a constant, too. When the billet diameter increases, the casting rate should be reduced correspondingly.
According to the heat transfer analysis of Airslip mold, an analytical model was presented to study the solidification shell thickness and the critical solidification shell thickness. The theoretical analysis and experimental results indicate that the product of solidification shell thickness and the casting rate is a constant, when the casting rate increases, the solidification shell thickness decreases and the billet surface is better, the variation of the casting rate brings the fluctuation of solidification shell thickness and therefore deteriorates the billet surface. It is also shown that the product of billet diameter and the casting rate is a constant, too. When the billet diameter increases, the casting rate should be reduced correspondingly.
2006, 35(4):625-628.
Abstract:
The effects of additive species, additive concentration, temperature, anode to cathode distance and current density on the electrochemical synthesis of tantalum ethoxide using sacrificing anode method have been investigated. The optimum conditions were tetramethylammonium chloride 0.04 mol/L, boiling temperature, distance 2 cm and current density 220 A/m2. After treating the mixed solution with general distillation and reduced distillation, the final product were characterized by fourier transform infrared(FTIR) spectrum, Raman spectra and elemental analyses. The product is tantalum penta-ethoxide. Current efficiency is more than 95%, and recovery ratio of tantalum during distillation is 82.8%.
The effects of additive species, additive concentration, temperature, anode to cathode distance and current density on the electrochemical synthesis of tantalum ethoxide using sacrificing anode method have been investigated. The optimum conditions were tetramethylammonium chloride 0.04 mol/L, boiling temperature, distance 2 cm and current density 220 A/m2. After treating the mixed solution with general distillation and reduced distillation, the final product were characterized by fourier transform infrared(FTIR) spectrum, Raman spectra and elemental analyses. The product is tantalum penta-ethoxide. Current efficiency is more than 95%, and recovery ratio of tantalum during distillation is 82.8%.
2006, 35(4):629-633.
Abstract:
Titanium diboride (TiB2) appears to be a promising material for corrosion prevention in aluminium industries. This paper first predicted the possibility of TiB2 formation in Ti-B-C system, and then focused on the preparation of TiB2 coatings by electroplating on the graphite in fluoride-chloride electrolytes (KF-KCl) containing K2TiF6 and KBF4 as the electrochemically-active components. The effect of current density and electroplating techniques on the surface leveling, compaction and grain size of coatings was investigated. The results show thick, adherent and uniform TiB2 coatings are obtained when the current density is 0.8 A/cm2; compared with continuous current plating (CCP), the surface leveling and compaction of coatings deposited by periodically interrupted current (PIC) are remarkably improved, and the crystal grain is finer. XRD analysis indicats that the coatings are composed of relatively pure TiB2 and the preferred orientation of coatings is (001) plane under experimental conditions, which is in accordance with the prediction of the two-dimensional crystal nuclei theory.
Titanium diboride (TiB2) appears to be a promising material for corrosion prevention in aluminium industries. This paper first predicted the possibility of TiB2 formation in Ti-B-C system, and then focused on the preparation of TiB2 coatings by electroplating on the graphite in fluoride-chloride electrolytes (KF-KCl) containing K2TiF6 and KBF4 as the electrochemically-active components. The effect of current density and electroplating techniques on the surface leveling, compaction and grain size of coatings was investigated. The results show thick, adherent and uniform TiB2 coatings are obtained when the current density is 0.8 A/cm2; compared with continuous current plating (CCP), the surface leveling and compaction of coatings deposited by periodically interrupted current (PIC) are remarkably improved, and the crystal grain is finer. XRD analysis indicats that the coatings are composed of relatively pure TiB2 and the preferred orientation of coatings is (001) plane under experimental conditions, which is in accordance with the prediction of the two-dimensional crystal nuclei theory.
2006, 35(4):634-637.
Abstract:
The microhardness of JCW-S-AM coatings prepared by high velocity electric arc spraying on conditions of different process parameters was tested by hardometer. According to the test results, the model on the relation between the JCW-S-AM coatings microhardness and the process parameters was established by means of GA-BP genetic neural network arithmetic. The optimum parameters were optimized with genetic algorithm. The results of analysis and calculation show that the spray voltage and spray current all affect the microhardness, and there exists certain interaction between spray voltage and spray current. By means of genetic algorithm, the optimum spray parameters theoretically are that spray voltage is 29 V, spray current is 200 A, the microhardness of JCW-S-AM coatings is biggest.
The microhardness of JCW-S-AM coatings prepared by high velocity electric arc spraying on conditions of different process parameters was tested by hardometer. According to the test results, the model on the relation between the JCW-S-AM coatings microhardness and the process parameters was established by means of GA-BP genetic neural network arithmetic. The optimum parameters were optimized with genetic algorithm. The results of analysis and calculation show that the spray voltage and spray current all affect the microhardness, and there exists certain interaction between spray voltage and spray current. By means of genetic algorithm, the optimum spray parameters theoretically are that spray voltage is 29 V, spray current is 200 A, the microhardness of JCW-S-AM coatings is biggest.
2006, 35(4):638-641.
Abstract:
用人工神经网络预测了电铸自支撑金刚石-镍复合膜中金刚石颗粒的含量、复合膜的厚度和表面微观形貌。结果表明,当阴极电流密度小于1.0A/dm2时,复合膜的表面均匀,无镍瘤;复合膜的沉积速率约为14μm/h。其预测的沉积结果与实际样品测量值接近,相对误差小于9.9%。人工神经网络能够充分体现电镀工艺参数与沉积结果之间的非线性关系和隐含关系,训练精度较高,具有较高的预测能力。
用人工神经网络预测了电铸自支撑金刚石-镍复合膜中金刚石颗粒的含量、复合膜的厚度和表面微观形貌。结果表明,当阴极电流密度小于1.0A/dm2时,复合膜的表面均匀,无镍瘤;复合膜的沉积速率约为14μm/h。其预测的沉积结果与实际样品测量值接近,相对误差小于9.9%。人工神经网络能够充分体现电镀工艺参数与沉积结果之间的非线性关系和隐含关系,训练精度较高,具有较高的预测能力。
2006, 35(4):642-646.
Abstract:
采用考虑热机耦合效应的刚塑性有限元方法,对正方体形7075铝合金的锻造过程和晶粒细化过程进行了数值模拟,所采用的晶粒细化模型为Yada模型。结果表明,锻件内的应力、应变、应变速率、温度分布不均,模型中心区域为易变形区,4个纵向棱边区和以上下接触表面为底面的接触锥形区为难变形区。细化首先开始于易变形区,再相继扩展到纵向棱边区和接触锥形区。应变速率和温度是决定晶粒尺寸的主要因素。增加应变速率,可使晶粒尺寸变小,但高应变速率使得锻件升温;而温度升高,使得晶粒尺寸长大。有利于晶粒细化的锻造工艺条件为:温度350℃~400℃,应变速率70s-1~100s-1,道次压缩比20%~25%。讨论了Yada模型的局限性,指明了它的适用范围。
采用考虑热机耦合效应的刚塑性有限元方法,对正方体形7075铝合金的锻造过程和晶粒细化过程进行了数值模拟,所采用的晶粒细化模型为Yada模型。结果表明,锻件内的应力、应变、应变速率、温度分布不均,模型中心区域为易变形区,4个纵向棱边区和以上下接触表面为底面的接触锥形区为难变形区。细化首先开始于易变形区,再相继扩展到纵向棱边区和接触锥形区。应变速率和温度是决定晶粒尺寸的主要因素。增加应变速率,可使晶粒尺寸变小,但高应变速率使得锻件升温;而温度升高,使得晶粒尺寸长大。有利于晶粒细化的锻造工艺条件为:温度350℃~400℃,应变速率70s-1~100s-1,道次压缩比20%~25%。讨论了Yada模型的局限性,指明了它的适用范围。
2006, 35(4):651-654.
Abstract:
The effect of the noble and heavy metal ion brighteners in acidic electroless nickel solution on properties of coatings including hardness, bonding force, porosity and corrosion resistance were investigated. These brighteners play a dominant role in coating structure from the measurements of AFM, XRD and XPS. The results show that the noble metal ion brighteners can greatly improve the electroless nickel coating performance, for example, reducing the surface coarseness and making the layer column smaller. Moreover, the amorphous structure get more remarkable due to presence of noble and heavy metal ion brighteners. XPS results reveal that Ni element exists in the form of Ni0 and Ni2+, while P exists in the form of negative ion and PO43-. So the brighteners are propitious to form protective film of Ni3(PO4)2.
The effect of the noble and heavy metal ion brighteners in acidic electroless nickel solution on properties of coatings including hardness, bonding force, porosity and corrosion resistance were investigated. These brighteners play a dominant role in coating structure from the measurements of AFM, XRD and XPS. The results show that the noble metal ion brighteners can greatly improve the electroless nickel coating performance, for example, reducing the surface coarseness and making the layer column smaller. Moreover, the amorphous structure get more remarkable due to presence of noble and heavy metal ion brighteners. XPS results reveal that Ni element exists in the form of Ni0 and Ni2+, while P exists in the form of negative ion and PO43-. So the brighteners are propitious to form protective film of Ni3(PO4)2.
2006, 35(4):655-658.
Abstract:
采用DTA分析Ti-23Al-25Nb合金和Ti-23Al-25Nb-0.36Y合金的相变特征,并根据DTA曲线特征制定热处理工艺,用SEM,XRD分析热处理后合金试样的显微组织及相组成,用TEM分析原始组织中钇的存在形式,用Instron-5569万能材料试验机进行室温压缩试验。结果表明,钇在原始组织中以Y2O3形式存在;钇没有改变Ti-23Al-25Nb合金的相变温度;加入钇后,在1320℃淬火,B2相晶粒比较粗大,随着淬火温度的降低,O相增加,并且O相板条变细而杂乱,有利于提高合金的塑性和抗蠕变性能;加入钇后,合金强度提高,原因是第二相粒子Y2O3弥散强化的结果。
采用DTA分析Ti-23Al-25Nb合金和Ti-23Al-25Nb-0.36Y合金的相变特征,并根据DTA曲线特征制定热处理工艺,用SEM,XRD分析热处理后合金试样的显微组织及相组成,用TEM分析原始组织中钇的存在形式,用Instron-5569万能材料试验机进行室温压缩试验。结果表明,钇在原始组织中以Y2O3形式存在;钇没有改变Ti-23Al-25Nb合金的相变温度;加入钇后,在1320℃淬火,B2相晶粒比较粗大,随着淬火温度的降低,O相增加,并且O相板条变细而杂乱,有利于提高合金的塑性和抗蠕变性能;加入钇后,合金强度提高,原因是第二相粒子Y2O3弥散强化的结果。
2006, 35(4):659-661.
Abstract:
通过交流电沉积的方法在铝阳极氧化膜的孔内沉积金属铜,制备了铝基抗菌功能性材料;测试了沉积铜的铝阳极氧化膜的抗菌性能。结果表明:电沉积铜的铝阳极氧化膜对大肠杆菌、绿脓杆菌、粪链球菌和金黄色葡萄球菌的抗菌率均大于95%。透射电子显微镜表征了铜在氧化膜孔内的沉积形貌,铜在铝阳极氧化膜孔内呈连续的线状形貌,直径为25nm。
通过交流电沉积的方法在铝阳极氧化膜的孔内沉积金属铜,制备了铝基抗菌功能性材料;测试了沉积铜的铝阳极氧化膜的抗菌性能。结果表明:电沉积铜的铝阳极氧化膜对大肠杆菌、绿脓杆菌、粪链球菌和金黄色葡萄球菌的抗菌率均大于95%。透射电子显微镜表征了铜在氧化膜孔内的沉积形貌,铜在铝阳极氧化膜孔内呈连续的线状形貌,直径为25nm。
2006, 35(4):662-664.
Abstract:
采用化学共沉淀法制备纳米级氧化铟锡复合粉体前驱物,煅烧得到纳米级氧化铟锡(ITO)复合粉体,用TG-DTA,XRD,TEM,ICP-AES,XRF和BET研究了纳米级ITO复合粉体的性能。前驱物铟锡氢氧化物的分解温度为291.5℃,300℃下烧结即可得到立方结构的ITO结晶粉体,Sn嵌入到In2O3晶格中,形成单相的ITO固溶体颗粒。随着温度的升高,ITO固溶体颗粒结晶更完全,晶粒长大。前驱物铟锡氢氧化物分别在600℃,800℃和900℃煅烧4h得到粒度均匀、分散性好、粒径为20nm~30nm的类球形ITO复合粉体。600℃煅烧得到的ITO复合粉体的纯度为99.995%,配比为In2O3:90.045%,SnO2:9.955%,比表面积为50.88m2/g。该粉体烧结活性高,将该粉体用简单的烧结工艺在1000℃烧制的ITO靶材相对理论密度达到99.25%。
采用化学共沉淀法制备纳米级氧化铟锡复合粉体前驱物,煅烧得到纳米级氧化铟锡(ITO)复合粉体,用TG-DTA,XRD,TEM,ICP-AES,XRF和BET研究了纳米级ITO复合粉体的性能。前驱物铟锡氢氧化物的分解温度为291.5℃,300℃下烧结即可得到立方结构的ITO结晶粉体,Sn嵌入到In2O3晶格中,形成单相的ITO固溶体颗粒。随着温度的升高,ITO固溶体颗粒结晶更完全,晶粒长大。前驱物铟锡氢氧化物分别在600℃,800℃和900℃煅烧4h得到粒度均匀、分散性好、粒径为20nm~30nm的类球形ITO复合粉体。600℃煅烧得到的ITO复合粉体的纯度为99.995%,配比为In2O3:90.045%,SnO2:9.955%,比表面积为50.88m2/g。该粉体烧结活性高,将该粉体用简单的烧结工艺在1000℃烧制的ITO靶材相对理论密度达到99.25%。
2006, 35(4):665-668.
Abstract:
先驱体聚铝碳硅烷经熔融纺丝、空气预氧化处理、1300℃烧成制得连续的含有少量铝和较多氧的SiC(OAl)纤维,即KD-A纤维。通过元素分析、拉伸强度测试及SEM,AFM,HRTEM,XRD等分析对纤维进行了表征。结果表明:连续KD-A纤维是非晶型的含铝SiC纤维,直径为12μm~14μm,具有较高的抗拉伸强度(2.6GPa)和弹性模量(210GPa),其耐高温和抗氧化性能明显优于Nicalon纤维,达到了Hi-Nicalon纤维的水平。
先驱体聚铝碳硅烷经熔融纺丝、空气预氧化处理、1300℃烧成制得连续的含有少量铝和较多氧的SiC(OAl)纤维,即KD-A纤维。通过元素分析、拉伸强度测试及SEM,AFM,HRTEM,XRD等分析对纤维进行了表征。结果表明:连续KD-A纤维是非晶型的含铝SiC纤维,直径为12μm~14μm,具有较高的抗拉伸强度(2.6GPa)和弹性模量(210GPa),其耐高温和抗氧化性能明显优于Nicalon纤维,达到了Hi-Nicalon纤维的水平。
2006, 35(4):669-672.
Abstract:
The particle reinforced aluminum alloy matrix composites, (Al2O3+Al3Zr)p/A359, was fabricated by In-situ reaction in melt A359 and Zr(CO3)2 system. During the fabrication process, a low frequency alternative electromagnetic field was employed to improve the properties of composites by EMS (electromagnetic stirring). The results of dry sliding friction experiments indicate that the wear resistance of composites is better than that of pure matrix alloy. And the wear resistance of composites under a heavy load is further improved by imposing EMS in the fabrication process. By comparison with the composites fabricated without imposing EMS, the critical transition load from mild wear to severe wear of the composites increases from 58.8 N to 78.8 N. The scanning electron microscopy (SEM) analysis of worn-out surfaces indicate that the wear mechanism of pure matrix alloy is adhesive wear and spalling wear, that of composites without EMS in fabrication is mainly abrasion and that of electromagnetic fabricated composites is pure abrasion.
The particle reinforced aluminum alloy matrix composites, (Al2O3+Al3Zr)p/A359, was fabricated by In-situ reaction in melt A359 and Zr(CO3)2 system. During the fabrication process, a low frequency alternative electromagnetic field was employed to improve the properties of composites by EMS (electromagnetic stirring). The results of dry sliding friction experiments indicate that the wear resistance of composites is better than that of pure matrix alloy. And the wear resistance of composites under a heavy load is further improved by imposing EMS in the fabrication process. By comparison with the composites fabricated without imposing EMS, the critical transition load from mild wear to severe wear of the composites increases from 58.8 N to 78.8 N. The scanning electron microscopy (SEM) analysis of worn-out surfaces indicate that the wear mechanism of pure matrix alloy is adhesive wear and spalling wear, that of composites without EMS in fabrication is mainly abrasion and that of electromagnetic fabricated composites is pure abrasion.
