Volume 34,Issue 3,2005 Table of Contents
2005, 34(3):337-340.
Abstract:
Methods of preparing foam materials, such as aluminium foam, titanium foam, silicon foam and lead foam, and how to control the composition and the porosity in order to prepare materials of different performances were presented. Excellent properties of foam materials, which were applied in auto industry, body in-planting material, optical material, micro-electronics, computer and lead-acid battery, etc., were emphatically introduced. Spacious market outlook was also previewed.
Methods of preparing foam materials, such as aluminium foam, titanium foam, silicon foam and lead foam, and how to control the composition and the porosity in order to prepare materials of different performances were presented. Excellent properties of foam materials, which were applied in auto industry, body in-planting material, optical material, micro-electronics, computer and lead-acid battery, etc., were emphatically introduced. Spacious market outlook was also previewed.
2005, 34(3):341-345.
Abstract:
The photocatalytic mechanism, catalogue and carrier of photocatalysts and its applications were described in this paper. According to their composition and structure, the photocatalysts are classified as simple oxide-type, nanometer sulfide, composite oxides, layer structure compound, AB2O4-type , complexes photocatalysts and so on. The development direction of photocatalyst is analyzed. The methods of improving the properties of photocatalysts and the factors influencing photocatalytic efficiency were discussed too.
The photocatalytic mechanism, catalogue and carrier of photocatalysts and its applications were described in this paper. According to their composition and structure, the photocatalysts are classified as simple oxide-type, nanometer sulfide, composite oxides, layer structure compound, AB2O4-type , complexes photocatalysts and so on. The development direction of photocatalyst is analyzed. The methods of improving the properties of photocatalysts and the factors influencing photocatalytic efficiency were discussed too.
2005, 34(3):346-349.
Abstract:
Gradient-dependent plasticity having characteristic length reflecting heterogeneity was used to deduce analytically non-uniform plastic strain in necked zone, and the external shape of the zone was described because the plastic strain and the plastic extension of the zone regardless of change of volume of the zone was calculated. In addition, the true stress was deduced because the minimum sectional area in the zone can be determined according to the external shape. The advantage of the present analytical results for true stress and true strain curve is that the related parameters have specific physical meanings, such as softening modulus describing brittleness, elastic modulus considering elasticity, characteristic length reflecting the heterogeneity, the gauge length involved in the present model to study the geometrical size effect. Comparisons of the existing experimental results for titanium and Ti-6Al-4V and the present analytical results were carried out and the new model considering microstructures and localized necking was verified. It is found that the brittleness and heterogeneity of Ti-6Al-4V are higher than those of CP titanium. The differences of the propagation velocity of the localized band in two kinds of materials are explained in terms of the different brittleness.
Gradient-dependent plasticity having characteristic length reflecting heterogeneity was used to deduce analytically non-uniform plastic strain in necked zone, and the external shape of the zone was described because the plastic strain and the plastic extension of the zone regardless of change of volume of the zone was calculated. In addition, the true stress was deduced because the minimum sectional area in the zone can be determined according to the external shape. The advantage of the present analytical results for true stress and true strain curve is that the related parameters have specific physical meanings, such as softening modulus describing brittleness, elastic modulus considering elasticity, characteristic length reflecting the heterogeneity, the gauge length involved in the present model to study the geometrical size effect. Comparisons of the existing experimental results for titanium and Ti-6Al-4V and the present analytical results were carried out and the new model considering microstructures and localized necking was verified. It is found that the brittleness and heterogeneity of Ti-6Al-4V are higher than those of CP titanium. The differences of the propagation velocity of the localized band in two kinds of materials are explained in terms of the different brittleness.
2005, 34(3):350-354.
Abstract:
用quantum Sutton-Chen多体势对AgxCu1-x在冷却速率为2×1012K/s凝固过程的模拟,发现AgxCu1-x在x=35～65范围内具有形成非晶的能力,特别是对应于二元相图共晶点的Ag60Cu40在凝固过程中二十面体和其它多面体结构不仅数目大,而且还具有极为稳定的遗传性,而最容易得到非晶态合金.证实了合金化效应对非晶态合金的形成倾向和稳定性的关键作用.此外采用键对及原子多面体类型指数法对凝固过程中微观结构组态变化的分析,不但能说明二十面体结构在非晶态合金形成和稳定性中所起的关键作用,又有助于对液态金属的凝固过程、非晶态微观结构特征的深入理解.
用quantum Sutton-Chen多体势对AgxCu1-x在冷却速率为2×1012K/s凝固过程的模拟,发现AgxCu1-x在x=35～65范围内具有形成非晶的能力,特别是对应于二元相图共晶点的Ag60Cu40在凝固过程中二十面体和其它多面体结构不仅数目大,而且还具有极为稳定的遗传性,而最容易得到非晶态合金.证实了合金化效应对非晶态合金的形成倾向和稳定性的关键作用.此外采用键对及原子多面体类型指数法对凝固过程中微观结构组态变化的分析,不但能说明二十面体结构在非晶态合金形成和稳定性中所起的关键作用,又有助于对液态金属的凝固过程、非晶态微观结构特征的深入理解.
2005, 34(3):355-358.
Abstract:
采用微分扫描式量热法(DSC)、拉伸试验和弯曲试验研究了形变对Ti36Ni49Hf15高温形状记忆合金相变及双程形状记忆效应的影响.结果表明,形变不影响合金的相变顺序.在马氏体状态下变形时,随形变量的增加,Ti36Ni49Hf15合金的马氏体相变温度略有下降,逆马氏体相变温度上升.当形变量一定时,合金在马氏体状态下不同温度变形,对合金的相变温度没有显著影响.Ti36Ni49Hf15高温记忆合金在马氏体状态下直接变形可以产生双程形状记忆效应,其双程可逆应变量随形变量的增加而增加.在随后的热循环过程中,合金的双程形状记忆效应在最初的几次循环过程中迅速下降,而后随循环次数的增加趋于稳定.
采用微分扫描式量热法(DSC)、拉伸试验和弯曲试验研究了形变对Ti36Ni49Hf15高温形状记忆合金相变及双程形状记忆效应的影响.结果表明,形变不影响合金的相变顺序.在马氏体状态下变形时,随形变量的增加,Ti36Ni49Hf15合金的马氏体相变温度略有下降,逆马氏体相变温度上升.当形变量一定时,合金在马氏体状态下不同温度变形,对合金的相变温度没有显著影响.Ti36Ni49Hf15高温记忆合金在马氏体状态下直接变形可以产生双程形状记忆效应,其双程可逆应变量随形变量的增加而增加.在随后的热循环过程中,合金的双程形状记忆效应在最初的几次循环过程中迅速下降,而后随循环次数的增加趋于稳定.
2005, 34(3):359-362.
Abstract:
The air-exposed surfaces of sintered UC samples at room temperature were examined by X-ray photoelectron spectroscopy (XPS). Elemental depth profiles reveal that the surface of UC consists of a top layer of small amounts of UO2+ ; this very thin layer is x followed by a layer containing uranium dioxide, uranium monocarbide and free carbon and then bulk UC. The binding energy of U4f7/2 and C1s peaks of UC is found to be 378.2 eV and 282 eV, respectively. Quantitative analysis indicates that the C/U atomic ratio of clean UC surfaces is approximately 1?1, which is consistent with stoichiometric UC, but there exists small amounts of dissolved oxygen on sputter-cleaned UC surfaces. The oxidation mechanism of UC has been also discussed.
The air-exposed surfaces of sintered UC samples at room temperature were examined by X-ray photoelectron spectroscopy (XPS). Elemental depth profiles reveal that the surface of UC consists of a top layer of small amounts of UO2+ ; this very thin layer is x followed by a layer containing uranium dioxide, uranium monocarbide and free carbon and then bulk UC. The binding energy of U4f7/2 and C1s peaks of UC is found to be 378.2 eV and 282 eV, respectively. Quantitative analysis indicates that the C/U atomic ratio of clean UC surfaces is approximately 1?1, which is consistent with stoichiometric UC, but there exists small amounts of dissolved oxygen on sputter-cleaned UC surfaces. The oxidation mechanism of UC has been also discussed.
2005, 34(3):363-366.
Abstract:
采用直流磁控溅射法制备了SmCo/Cr,SmCo/CrTi 和SmCo/CrTi/Cr 系列薄膜。SmCo 薄膜的XRD 结果表明:在Cr 底层中添加Ti,得到的CrTi,CrTi/Cr 底层也是以(110)面择优取向的,但是和Cr 底层相比,衍射峰的位置由44.39°偏移到44.19°。薄膜的磁学性能由振动样品磁强计(VSM)测定,分析VSM 的测量结果可知,用CrTi 和CrTi/Cr做底层,SmCo 薄膜的矫顽力Hc、矩形比S、矫顽力矩形比S*的值都比Cr 底层的大,并且磁反转体积V*的值比Cr 底层的小。SmCo 薄膜的δM(H)曲线说明,Cr 做底层时,薄膜晶粒间的相互作用为极化作用,CrTi,CrTi/Cr 做底层时,薄膜晶粒间的相互作用为交换耦合相互作用。
采用直流磁控溅射法制备了SmCo/Cr,SmCo/CrTi 和SmCo/CrTi/Cr 系列薄膜。SmCo 薄膜的XRD 结果表明:在Cr 底层中添加Ti,得到的CrTi,CrTi/Cr 底层也是以(110)面择优取向的,但是和Cr 底层相比,衍射峰的位置由44.39°偏移到44.19°。薄膜的磁学性能由振动样品磁强计(VSM)测定,分析VSM 的测量结果可知,用CrTi 和CrTi/Cr做底层,SmCo 薄膜的矫顽力Hc、矩形比S、矫顽力矩形比S*的值都比Cr 底层的大,并且磁反转体积V*的值比Cr 底层的小。SmCo 薄膜的δM(H)曲线说明,Cr 做底层时,薄膜晶粒间的相互作用为极化作用,CrTi,CrTi/Cr 做底层时,薄膜晶粒间的相互作用为交换耦合相互作用。
2005, 34(3):367-370.
Abstract:
Dimension of injected parts reflects the quality of injection molded parts, and plays an important role in controlling defects and final dimension of parts during subsequent debonding and sintering. On the premise of same shrinkage in different directions during sintering, a mathematic model of controlling injected parts dimension and qualities by controlling the weight deviations of injected green parts, which is proved to be correct in the experiment is proposed.
Dimension of injected parts reflects the quality of injection molded parts, and plays an important role in controlling defects and final dimension of parts during subsequent debonding and sintering. On the premise of same shrinkage in different directions during sintering, a mathematic model of controlling injected parts dimension and qualities by controlling the weight deviations of injected green parts, which is proved to be correct in the experiment is proposed.
2005, 34(3):371-374.
Abstract:
利用材料测试系统(MTS)、X-Ray衍射(XRD)和扫描电镜(SEM)等手段研究了Nd基大块金属玻璃的变形行为和断裂特征.Nd基大块金属玻璃样品在室温下是脆性断裂,大约在500 K时变形模式从非均匀变形转变为均匀变形,在523 K以上表现出显著的塑性变形.在5×10-4 m/s的应变速率下,这种Nd基大块金属玻璃材料在523 K～600 K之间出现明显的屈服应力下降现象,随后进入1种稳定的粘性流动状态,而且这种屈服下降现象与温度和应变速率有关.这种在过冷液相区的变形行为与其他大块金属玻璃变形特征相似.合金的这种塑性变形行为表明了其存在稳定的过冷液相区,同时对其变形行为的研究有助于进一步了解Nd基大块金属玻璃的反常热稳定性.
利用材料测试系统(MTS)、X-Ray衍射(XRD)和扫描电镜(SEM)等手段研究了Nd基大块金属玻璃的变形行为和断裂特征.Nd基大块金属玻璃样品在室温下是脆性断裂,大约在500 K时变形模式从非均匀变形转变为均匀变形,在523 K以上表现出显著的塑性变形.在5×10-4 m/s的应变速率下,这种Nd基大块金属玻璃材料在523 K～600 K之间出现明显的屈服应力下降现象,随后进入1种稳定的粘性流动状态,而且这种屈服下降现象与温度和应变速率有关.这种在过冷液相区的变形行为与其他大块金属玻璃变形特征相似.合金的这种塑性变形行为表明了其存在稳定的过冷液相区,同时对其变形行为的研究有助于进一步了解Nd基大块金属玻璃的反常热稳定性.
2005, 34(3):375-379.
Abstract:
为了提高AZ91D 镁合金的力学性能与阻尼性能,利用OM(光学金相显微镜)和XRD 分析了金属型铸造不同Ce 含量AZ91D 合金的显微组织和相组成,测试了室温力学性能,用悬臂梁技术测量了其阻尼性能。结果表明,AZ91D合金中加入一定量Ce 后生成的Al4Ce 相被推移到生长界面,阻碍枝晶的自由生长,从而细化合金铸态组织;Ce 能提高AZ91D 合金室温抗拉强度,而对其屈服强度和延伸率影响不大,Ce 能提高合金的阻尼性能;AZ91D-0.7%Ce 合金晶粒细化效果佳,力学性能较理想,阻尼性能最高;合金的阻尼行为可用Granato-Lücke 理论来解释。
为了提高AZ91D 镁合金的力学性能与阻尼性能,利用OM(光学金相显微镜)和XRD 分析了金属型铸造不同Ce 含量AZ91D 合金的显微组织和相组成,测试了室温力学性能,用悬臂梁技术测量了其阻尼性能。结果表明,AZ91D合金中加入一定量Ce 后生成的Al4Ce 相被推移到生长界面,阻碍枝晶的自由生长,从而细化合金铸态组织;Ce 能提高AZ91D 合金室温抗拉强度,而对其屈服强度和延伸率影响不大,Ce 能提高合金的阻尼性能;AZ91D-0.7%Ce 合金晶粒细化效果佳,力学性能较理想,阻尼性能最高;合金的阻尼行为可用Granato-Lücke 理论来解释。
2005, 34(3):380-384.
Abstract:
研究了微量Ti对Mg-9Al二元合金铸造显微组织和性能的影响.研究发现,Ti的加入,使得Mg-9Al合金的塑性增加,明显提高了Mg-9Al合金的抗腐蚀性能.分析结果表明,残留Ti弥散分布在合金的基体中,Ti的加入有效降低了Fe的含量,一定程度上“净化”了合金液,抑制了合金凝固时的异质形核,使组织晶粒粗化.实验发现,炉前加入0.12%的Ti(质量分数,下同)时,Mg-9Al合金的晶粒大小由145μm增大到188μm.随着Ti的加入,Mg-9Al铸造组织中β相的形态,由半连续骨骼网状改变为短条状和颗粒状.当炉前加入0.12%的Ti时,Mg-9Al合金的综合性能较佳.
研究了微量Ti对Mg-9Al二元合金铸造显微组织和性能的影响.研究发现,Ti的加入,使得Mg-9Al合金的塑性增加,明显提高了Mg-9Al合金的抗腐蚀性能.分析结果表明,残留Ti弥散分布在合金的基体中,Ti的加入有效降低了Fe的含量,一定程度上“净化”了合金液,抑制了合金凝固时的异质形核,使组织晶粒粗化.实验发现,炉前加入0.12%的Ti(质量分数,下同)时,Mg-9Al合金的晶粒大小由145μm增大到188μm.随着Ti的加入,Mg-9Al铸造组织中β相的形态,由半连续骨骼网状改变为短条状和颗粒状.当炉前加入0.12%的Ti时,Mg-9Al合金的综合性能较佳.
2005, 34(3):385-388.
Abstract:
在Gleeble-1500D热模拟实验机上对30ZrCp/W复合材料进行高温压缩实验,变形温度和应变速率分别为800℃～1 200℃和10-3 s^-1～1 s^-1,研究其高温压缩变形的流变应力行为.研究表明:随变形温度升高,复合材料的流变应力下降,在10-3s^-1和1200℃下,抗压强度为948.7 MPa.在800℃下发生伪塑性变形,未达到预设变形量,真应力-真应变曲线上表现出的塑性为伪塑性,其是由微裂纹的萌生-钝化引起的.随变形温度升高,复合材料发生动态回复再结晶.随应变速率升高,真应力-真应变曲线形状从“锯齿”型向“平滑”型转变.复合材料对应变速率不敏感,随应变速率升高,复合材料的流变应力略有升高.在800℃和1s^-1下,复合材料的抗压强度为1176.9MPa.用Arrhenius方程描述复合材料在1000℃～1200℃的热变形行为,变形激活能为811.4 kJ/mol.
在Gleeble-1500D热模拟实验机上对30ZrCp/W复合材料进行高温压缩实验,变形温度和应变速率分别为800℃～1 200℃和10-3 s^-1～1 s^-1,研究其高温压缩变形的流变应力行为.研究表明:随变形温度升高,复合材料的流变应力下降,在10-3s^-1和1200℃下,抗压强度为948.7 MPa.在800℃下发生伪塑性变形,未达到预设变形量,真应力-真应变曲线上表现出的塑性为伪塑性,其是由微裂纹的萌生-钝化引起的.随变形温度升高,复合材料发生动态回复再结晶.随应变速率升高,真应力-真应变曲线形状从“锯齿”型向“平滑”型转变.复合材料对应变速率不敏感,随应变速率升高,复合材料的流变应力略有升高.在800℃和1s^-1下,复合材料的抗压强度为1176.9MPa.用Arrhenius方程描述复合材料在1000℃～1200℃的热变形行为,变形激活能为811.4 kJ/mol.
2005, 34(3):389-392.
Abstract:
The atom structure models of two kinds of quasicrystal in Zr-base amorphous alloys were set up by using the conjugate structure model of quasicrystals. The effects of alloying elements on the crystallization behavior of Zr-base amorphous alloys were investigated by recursion method. The results show that two kinds of quasicrystal -Zr6Ni, Ni6Zr clusters are exist in Zr-base amorphous alloys, and alloying elements (Ag, Pt, Pd, Au) occupy the sites of Ni ( or Cu) in the quasicrystal phase, and that increase the interaction of neighbor atoms, which explains the fact of alloying elements (Ag, Pd, Pt, Au) promoting the stable growth of the quasicrystal phase.
The atom structure models of two kinds of quasicrystal in Zr-base amorphous alloys were set up by using the conjugate structure model of quasicrystals. The effects of alloying elements on the crystallization behavior of Zr-base amorphous alloys were investigated by recursion method. The results show that two kinds of quasicrystal -Zr6Ni, Ni6Zr clusters are exist in Zr-base amorphous alloys, and alloying elements (Ag, Pt, Pd, Au) occupy the sites of Ni ( or Cu) in the quasicrystal phase, and that increase the interaction of neighbor atoms, which explains the fact of alloying elements (Ag, Pd, Pt, Au) promoting the stable growth of the quasicrystal phase.
2005, 34(3):393-396.
Abstract:
利用扫描电镜(SEM)和盐雾腐蚀试验等手段,研究了镁合金在不同电导率溶液中微弧氧化处理生成陶瓷层的生长规律及耐蚀性。结果表明:随溶液电导率的增大,发生微弧氧化现象的起弧电压减小,微弧氧化陶瓷层厚度表现出近似线性增长,陶瓷层表面微孔数目逐渐减少,微孔孔径逐渐增大,陶瓷层内显微缺陷数量逐渐增多;陶瓷层的耐蚀性随电导率的增大表现出先增后减的变化趋势,在溶液电导率为4 (?·m)-1～6 (?·m)-1 时,陶瓷层的耐蚀性较好。
利用扫描电镜(SEM)和盐雾腐蚀试验等手段,研究了镁合金在不同电导率溶液中微弧氧化处理生成陶瓷层的生长规律及耐蚀性。结果表明:随溶液电导率的增大,发生微弧氧化现象的起弧电压减小,微弧氧化陶瓷层厚度表现出近似线性增长,陶瓷层表面微孔数目逐渐减少,微孔孔径逐渐增大,陶瓷层内显微缺陷数量逐渐增多;陶瓷层的耐蚀性随电导率的增大表现出先增后减的变化趋势,在溶液电导率为4 (?·m)-1～6 (?·m)-1 时,陶瓷层的耐蚀性较好。
2005, 34(3):397-400.
Abstract:
阐述了指数曲线拟合方法和多项式拟合方法.分别用上述方法对52条卸载过程载荷-位移曲线进行了拟合,其中多项式的最高次数分别选为2～6种.在NANOINDENTERⅡ上对13个试样进行了压入实验,试样包括4个块体材料试样和9个膜/基材料试样,最大压入深度分为2组,即:一组为200 nm和500 nm,另一组为1 μm和2 μm.在每种压入深度下,对每个试样进行两次压入.通过上述实验,13个试样可得到52条卸载过程载荷-位移曲线的数据文件.用所述拟合方法对所有卸载曲线进行了拟合并得到相应的拟合曲线参数.用所得到的参数对试样的硬度和弹性模量进行了评定,对各种曲线拟合方法得到的载荷-位移拟合曲线与实测的载荷-位移曲线之间的关系进行了分析.分析结果表明:在上述曲线拟合方法中,5次多项式曲线拟合是最佳的拟合方法,而指数曲线拟合是最差的拟合方法,曲线拟合方法对纳米压入法材料力学性能的测量结果产生较大的影响.
阐述了指数曲线拟合方法和多项式拟合方法.分别用上述方法对52条卸载过程载荷-位移曲线进行了拟合,其中多项式的最高次数分别选为2～6种.在NANOINDENTERⅡ上对13个试样进行了压入实验,试样包括4个块体材料试样和9个膜/基材料试样,最大压入深度分为2组,即:一组为200 nm和500 nm,另一组为1 μm和2 μm.在每种压入深度下,对每个试样进行两次压入.通过上述实验,13个试样可得到52条卸载过程载荷-位移曲线的数据文件.用所述拟合方法对所有卸载曲线进行了拟合并得到相应的拟合曲线参数.用所得到的参数对试样的硬度和弹性模量进行了评定,对各种曲线拟合方法得到的载荷-位移拟合曲线与实测的载荷-位移曲线之间的关系进行了分析.分析结果表明:在上述曲线拟合方法中,5次多项式曲线拟合是最佳的拟合方法,而指数曲线拟合是最差的拟合方法,曲线拟合方法对纳米压入法材料力学性能的测量结果产生较大的影响.
2005, 34(3):401-404.
Abstract:
Effect of specimen size on the residual stress distribution of Al2O3/Nb joint is studied using numerical analysis. It can be concluded that the difference of specimen size can greatly influence the stress distribution. When the height of the specimen increased, the residual stress did not change evidently, and the residual would not change any more with the height increased to some degree with the width of specimen increasing, the residual stress increased firstly. But when the width reached 25 mm, the residual stress decreased instead. In conclusion, increasing specimen size is beneficial to both residual stress decrease and structure design in practice.
Effect of specimen size on the residual stress distribution of Al2O3/Nb joint is studied using numerical analysis. It can be concluded that the difference of specimen size can greatly influence the stress distribution. When the height of the specimen increased, the residual stress did not change evidently, and the residual would not change any more with the height increased to some degree with the width of specimen increasing, the residual stress increased firstly. But when the width reached 25 mm, the residual stress decreased instead. In conclusion, increasing specimen size is beneficial to both residual stress decrease and structure design in practice.
2005, 34(3):405-408.
Abstract:
The contact angles of Ag on SnO2 with different CuO content were measured by the sessile drop method, and the morphology and composition of transition zone of the interfaces were analyzed by SEM and EPMA technique. The results show that the wettability of Ag on SnO2 is improved by increasing the CuO content. The contact angle of Ag/SnO2 decreases from 90oto 29o with 7% CuO content. When CuO dopant is added into SnO2, Ag liquid can infiltrate into MeO, and a little MeO diffuses into Ag zone. So the strong interfacial bonding is obtained.
The contact angles of Ag on SnO2 with different CuO content were measured by the sessile drop method, and the morphology and composition of transition zone of the interfaces were analyzed by SEM and EPMA technique. The results show that the wettability of Ag on SnO2 is improved by increasing the CuO content. The contact angle of Ag/SnO2 decreases from 90oto 29o with 7% CuO content. When CuO dopant is added into SnO2, Ag liquid can infiltrate into MeO, and a little MeO diffuses into Ag zone. So the strong interfacial bonding is obtained.
2005, 34(3):409-412.
Abstract:
为了得到光电化学性能稳定、光催化活性好、制备方法简便的TiO2光电极,采用涂覆法制备了纳米TiO2薄膜光电极.XRD,SEM结果表明电极上涂覆的TiO2的晶型为锐钛型,纳米TiO2在电极表面分布均匀,薄膜厚度在10μm左右,且电极表面有一定的粗糙度.交流阻抗图谱分析显示TiO2电极在光照下能进行光电化学反应.应用于20mg/L苯酚溶液的降解中,结果表明,该电极光电催化降解性能优于光催化降解性能,电场在降解过程中发挥了作用;对照态光氧化过程基本无化学反应发生;暗态下电极上也无吸附现象;反应后电极无剥落损伤.
为了得到光电化学性能稳定、光催化活性好、制备方法简便的TiO2光电极,采用涂覆法制备了纳米TiO2薄膜光电极.XRD,SEM结果表明电极上涂覆的TiO2的晶型为锐钛型,纳米TiO2在电极表面分布均匀,薄膜厚度在10μm左右,且电极表面有一定的粗糙度.交流阻抗图谱分析显示TiO2电极在光照下能进行光电化学反应.应用于20mg/L苯酚溶液的降解中,结果表明,该电极光电催化降解性能优于光催化降解性能,电场在降解过程中发挥了作用;对照态光氧化过程基本无化学反应发生;暗态下电极上也无吸附现象;反应后电极无剥落损伤.
2005, 34(3):413-416.
Abstract:
A contrastive experiment was conducted by using 4 key process parameters, i.e. concentration of sodium tungstate, current density, pH value and temperature that have greater influences on the electro deposition of Ni-W alloy nanocrystalline. Influences on the deposition rate, microhardness and surface of plating were studied respectively, which would provide basis for the preparation of Ni-W alloy nanocrystalline. At the same time, the plating of Ni-W alloy nanocrystalline was obtained, the size of which was10.09 nm.
A contrastive experiment was conducted by using 4 key process parameters, i.e. concentration of sodium tungstate, current density, pH value and temperature that have greater influences on the electro deposition of Ni-W alloy nanocrystalline. Influences on the deposition rate, microhardness and surface of plating were studied respectively, which would provide basis for the preparation of Ni-W alloy nanocrystalline. At the same time, the plating of Ni-W alloy nanocrystalline was obtained, the size of which was10.09 nm.
2005, 34(3):417-420.
Abstract:
通过爆炸压实烧结纳米ITO粉末制备了ITO陶瓷靶材，结果表明爆炸冲击压实在靶材的后续烧结密实过程中起到了促进作用，它与常规的加压烧结相比，具有操作简单，设备要求低等很多优点。经过爆炸压实的烧结靶材具有细小的晶体颗粒，比商业靶材的晶粒度小约1个数量级。
通过爆炸压实烧结纳米ITO粉末制备了ITO陶瓷靶材，结果表明爆炸冲击压实在靶材的后续烧结密实过程中起到了促进作用，它与常规的加压烧结相比，具有操作简单，设备要求低等很多优点。经过爆炸压实的烧结靶材具有细小的晶体颗粒，比商业靶材的晶粒度小约1个数量级。
2005, 34(3):421-424.
Abstract:
MoO3 hydrosol was prepared by precipitation method. The effect factors on hydrosol were discussed systematically. TEM photos show that the MoO3 nanoparticles are spherical in shape, the size is about 60 nm, particle size distribution is in narrow range. ED images indicate that the MoO3 nanoparticles are polycrystalline structure. UV-VIS analysis show that the MoO3 nanoparticles hydrosol had good photochromic effect.
MoO3 hydrosol was prepared by precipitation method. The effect factors on hydrosol were discussed systematically. TEM photos show that the MoO3 nanoparticles are spherical in shape, the size is about 60 nm, particle size distribution is in narrow range. ED images indicate that the MoO3 nanoparticles are polycrystalline structure. UV-VIS analysis show that the MoO3 nanoparticles hydrosol had good photochromic effect.
2005, 34(3):425-428.
Abstract:
Nanocrystalline La2O3 was prepared by sol-gel process using common La2O3, HNO3 and PEG. The decomposition process of the precursor powder and the calcened nanocrystalline La2O3 formed at the end were charactered with various techniques: TG-DTA, XRD and TEM and the effects of some factors such as pH value of the solution, stirring rate and the amount of the PEG in the solution on the particle size and morphology are investigated. The result shows that the nanocrystalline La2O3 can be obtained with particle diameter of 30 nm~50 nm under appropriate conditions.
Nanocrystalline La2O3 was prepared by sol-gel process using common La2O3, HNO3 and PEG. The decomposition process of the precursor powder and the calcened nanocrystalline La2O3 formed at the end were charactered with various techniques: TG-DTA, XRD and TEM and the effects of some factors such as pH value of the solution, stirring rate and the amount of the PEG in the solution on the particle size and morphology are investigated. The result shows that the nanocrystalline La2O3 can be obtained with particle diameter of 30 nm~50 nm under appropriate conditions.
2005, 34(3):429-432.
Abstract:
TiO2 codoped with antimony and chromium was prepared by coprecipation method. The characters of samples were measured by XRD, TEM, BET and DRS methods. TiO2 codoped with antimony and chromium shows intense absorption bands in the visible light region. Codoped samples are presented with enhanced performance over nondoped samples and TiO2 doped with only antimony.
TiO2 codoped with antimony and chromium was prepared by coprecipation method. The characters of samples were measured by XRD, TEM, BET and DRS methods. TiO2 codoped with antimony and chromium shows intense absorption bands in the visible light region. Codoped samples are presented with enhanced performance over nondoped samples and TiO2 doped with only antimony.
2005, 34(3):433-435.
Abstract:
Metallic cementation treatment about Al, Zn elements on ZM5 magnesium alloy was conducted by solid diffusion.It was shown that the solid diffusion layer was mainly composed of Mg-Al-Zn intermetallic compounds and Mg-Al-Zn solid solution transition zone that had more Zn and Al elements than standard ZM5 magnesium substrate did. The test indicated that the microhardness values of Mg-Al-Zn intermetallic compounds were much higher than that of the substrate, and this would greatly contribute to the enhancement of wear resistance. The diffusion alloying layer was an effective corrosion barrier to decrease the corrosion rate for ZM5 magnesium alloy when exposed to 3.0% NaCl solutions.
Metallic cementation treatment about Al, Zn elements on ZM5 magnesium alloy was conducted by solid diffusion.It was shown that the solid diffusion layer was mainly composed of Mg-Al-Zn intermetallic compounds and Mg-Al-Zn solid solution transition zone that had more Zn and Al elements than standard ZM5 magnesium substrate did. The test indicated that the microhardness values of Mg-Al-Zn intermetallic compounds were much higher than that of the substrate, and this would greatly contribute to the enhancement of wear resistance. The diffusion alloying layer was an effective corrosion barrier to decrease the corrosion rate for ZM5 magnesium alloy when exposed to 3.0% NaCl solutions.
2005, 34(3):436-438.
Abstract:
采用室温固相化学反应前驱体法合成了亚微米级的(La,Ce,Tb)PO4绿色荧光粉.利用热重-差示热分析(TG-DTA)、X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)等实验技术,研究了荧光粉的形成过程,并对粉体尺寸、形貌及发光性能进行研究.结果表明:将前驱体在900℃煅烧后,产物为单斜晶系、独居石结构的正磷酸盐.粉末为亚微米级的球形颗粒.在272 nm紫外线激发下发绿色荧光,发射主峰在548 nm.同时表明:用室温固相化学反应前驱体法合成的(La,Ce,Tb)PO4是1种性能优良的荧光粉.
采用室温固相化学反应前驱体法合成了亚微米级的(La,Ce,Tb)PO4绿色荧光粉.利用热重-差示热分析(TG-DTA)、X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)等实验技术,研究了荧光粉的形成过程,并对粉体尺寸、形貌及发光性能进行研究.结果表明:将前驱体在900℃煅烧后,产物为单斜晶系、独居石结构的正磷酸盐.粉末为亚微米级的球形颗粒.在272 nm紫外线激发下发绿色荧光,发射主峰在548 nm.同时表明:用室温固相化学反应前驱体法合成的(La,Ce,Tb)PO4是1种性能优良的荧光粉.
2005, 34(3):439-442.
Abstract:
采用机械合金化、冷压与热挤压法制备了Al-15%Pb-4%Si-1%Sn-1.5%Cu(质量分数)轴瓦合金.实验结果表明,合金中Pb晶粒为纳米晶,Al以2种形态存在于合金体系中,一部分为亚微米晶体,另一部分为非晶相.合金的抗压强度和硬度值都随热挤压温度的升高而降低;热挤压温度为400℃时,合金的抗压强度σbe和抗压屈服强度σ0.2分别为610 MPa和440 MPa;其HV值达到1 820 MPa,高于采用其它方法制备的Al-Pb系轴瓦合金的值.
采用机械合金化、冷压与热挤压法制备了Al-15%Pb-4%Si-1%Sn-1.5%Cu(质量分数)轴瓦合金.实验结果表明,合金中Pb晶粒为纳米晶,Al以2种形态存在于合金体系中,一部分为亚微米晶体,另一部分为非晶相.合金的抗压强度和硬度值都随热挤压温度的升高而降低;热挤压温度为400℃时,合金的抗压强度σbe和抗压屈服强度σ0.2分别为610 MPa和440 MPa;其HV值达到1 820 MPa,高于采用其它方法制备的Al-Pb系轴瓦合金的值.
2005, 34(3):443-446.
Abstract:
In order to search a new process of fabricating TiAl intermetallic compounds with favorable combination of properties, this paper investigated the microstructure and thermal stability of Al-10wt.%Ti powders synthesized by mechanical milling. The experimental results show that Al, Ti particle and grain size decrease rapidly with the increase of milling time, and that the more milling time, the more energy stored in the composite powders. Consequently, the activation energy of the reaction for Al-Ti intermetallics decreases obviously. It is mechanical milling that causes a large number of crystal defects such as dislocations, vacancies, stacking fault and grain boundaries, hence raise the internal energy and the diffusivity. The final equilibrium phase of Al-10wt.%Ti powder which was sintered is DO22-Al3Ti.
In order to search a new process of fabricating TiAl intermetallic compounds with favorable combination of properties, this paper investigated the microstructure and thermal stability of Al-10wt.%Ti powders synthesized by mechanical milling. The experimental results show that Al, Ti particle and grain size decrease rapidly with the increase of milling time, and that the more milling time, the more energy stored in the composite powders. Consequently, the activation energy of the reaction for Al-Ti intermetallics decreases obviously. It is mechanical milling that causes a large number of crystal defects such as dislocations, vacancies, stacking fault and grain boundaries, hence raise the internal energy and the diffusivity. The final equilibrium phase of Al-10wt.%Ti powder which was sintered is DO22-Al3Ti.
2005, 34(3):447-451.
Abstract:
Metastable single phase with CaCu5 type structure for Co free over-stoichiometric La(NiMn)6 alloys were obtained by non-equilibrium processing of melt spinning. The crystal structure and electrochemical properties were investigated comparatively. The XRD results show that the La(NiMn)6 alloys prepared by melt spinning, in comparison with the as-cast alloys, present a single phase with CaCu5 type. The crystal lattice constants a and c exhibit a anisotropic change. With the increase of cooling rate, the a axis decreases and c axis and ratio of c/a value increase. The electrochemical analyses show that when cooling rate increases from 20 m/s to 50 m/s, the MH electrodes discharge capacity reach 277 mAh/g~256 mAh/g and the capacity retention is 63%~97.8% after 100 cycling number. The alloys prepared by melt spinning show a good cycling stability, but a lower discharge capacity and worse activation kinetics than that of the as-cast alloys.
Metastable single phase with CaCu5 type structure for Co free over-stoichiometric La(NiMn)6 alloys were obtained by non-equilibrium processing of melt spinning. The crystal structure and electrochemical properties were investigated comparatively. The XRD results show that the La(NiMn)6 alloys prepared by melt spinning, in comparison with the as-cast alloys, present a single phase with CaCu5 type. The crystal lattice constants a and c exhibit a anisotropic change. With the increase of cooling rate, the a axis decreases and c axis and ratio of c/a value increase. The electrochemical analyses show that when cooling rate increases from 20 m/s to 50 m/s, the MH electrodes discharge capacity reach 277 mAh/g~256 mAh/g and the capacity retention is 63%~97.8% after 100 cycling number. The alloys prepared by melt spinning show a good cycling stability, but a lower discharge capacity and worse activation kinetics than that of the as-cast alloys.
2005, 34(3):452-454.
Abstract:
采用磁控溅射方法制备金属锑薄膜,并把它作为锂离子二次电池负极进行研究。研究发现,通过磁控溅射比较容易控制条件得到符合条件的锑薄膜,并且薄膜锑有较平的吸放锂平台。另外,不同厚度对锑薄膜的吸放锂性能有较显著的影响,较薄的锑薄膜有着更好的电化学吸放锂性能,经过15 个循环后其脱锂容量仍保持在400 mAh·g-1 以上。
采用磁控溅射方法制备金属锑薄膜,并把它作为锂离子二次电池负极进行研究。研究发现,通过磁控溅射比较容易控制条件得到符合条件的锑薄膜,并且薄膜锑有较平的吸放锂平台。另外,不同厚度对锑薄膜的吸放锂性能有较显著的影响,较薄的锑薄膜有着更好的电化学吸放锂性能,经过15 个循环后其脱锂容量仍保持在400 mAh·g-1 以上。
2005, 34(3):455-458.
Abstract:
用伏安电荷容量表征了聚合前驱体法制备的Ti/TiO2电极的热分解温度和热分解时间对电极电催化活性的影响,用XRD,ESEM,TEM对所制电极的表面结构、形貌及TiO2的粒径进行了表征.实验结果表明:热分解温度和热分解时间对Ti/TiO2电极的伏安电荷容量有显著的影响,在热分解温度低于500℃时,延长热分解时间有利于提高电极的电催化活性.热分解反应温度大于500℃后,增长热分解时间,电极的电催化活性减小.不同热分解温度和热分解时间下所形成的不同的电极表面结构和形貌影响了Ti/TiO2电极的电催化活性.
用伏安电荷容量表征了聚合前驱体法制备的Ti/TiO2电极的热分解温度和热分解时间对电极电催化活性的影响,用XRD,ESEM,TEM对所制电极的表面结构、形貌及TiO2的粒径进行了表征.实验结果表明:热分解温度和热分解时间对Ti/TiO2电极的伏安电荷容量有显著的影响,在热分解温度低于500℃时,延长热分解时间有利于提高电极的电催化活性.热分解反应温度大于500℃后,增长热分解时间,电极的电催化活性减小.不同热分解温度和热分解时间下所形成的不同的电极表面结构和形貌影响了Ti/TiO2电极的电催化活性.
2005, 34(3):459-462.
Abstract:
Zr-Si-N diffusion barrier films were deposited by reactive magnetron sputtering with different negative bias. The results reveal that the Si content and resistivity of the Zr-Si-N films decrease as negative bias increases. The crystalline phase increases with the increase of negative bias. The thermal stability of Zr-Si-N diffusion barrier was so good that Zr-Si-N diffusion barrier can effectively prevent from the diffusion of Cu.
Zr-Si-N diffusion barrier films were deposited by reactive magnetron sputtering with different negative bias. The results reveal that the Si content and resistivity of the Zr-Si-N films decrease as negative bias increases. The crystalline phase increases with the increase of negative bias. The thermal stability of Zr-Si-N diffusion barrier was so good that Zr-Si-N diffusion barrier can effectively prevent from the diffusion of Cu.
2005, 34(3):463-466.
Abstract:
为了改善空气扩散电极的电催化性能,提高锌空气电池的放电电流,采用溶胶-凝胶法制备了分子式为La1-xSrxMnO3的锌空气电池用电催化剂.通过X射线衍射(XRD)、稳态电流-电压极化曲线等方法研究了La1-xSrxMnO3催化剂的结构与电催化性能,并将其作为锌空气电池催化剂装配成AA型锌空气电池进行恒流放电测试.研究结果表明,当分子式中的x=0.3、热处理温度为700℃时,所合成催化剂La0.7Sr0.3MnO3具有最优的电催化活性;XRD的分析证实,该催化剂的结构为完美的钙钛矿型晶体结构;分别以La0.7Sr0.3MnO3和LaMnO3为催化剂的AA型锌空气电池的放电容量分别为4800mAh和4200mAh,前者比后者的放电比能量有显著的提高.该催化剂的研制成功将有助于加快锌空气电池的实用化进程.
为了改善空气扩散电极的电催化性能,提高锌空气电池的放电电流,采用溶胶-凝胶法制备了分子式为La1-xSrxMnO3的锌空气电池用电催化剂.通过X射线衍射(XRD)、稳态电流-电压极化曲线等方法研究了La1-xSrxMnO3催化剂的结构与电催化性能,并将其作为锌空气电池催化剂装配成AA型锌空气电池进行恒流放电测试.研究结果表明,当分子式中的x=0.3、热处理温度为700℃时,所合成催化剂La0.7Sr0.3MnO3具有最优的电催化活性;XRD的分析证实,该催化剂的结构为完美的钙钛矿型晶体结构;分别以La0.7Sr0.3MnO3和LaMnO3为催化剂的AA型锌空气电池的放电容量分别为4800mAh和4200mAh,前者比后者的放电比能量有显著的提高.该催化剂的研制成功将有助于加快锌空气电池的实用化进程.
2005, 34(3):467-470.
Abstract:
采用溶胶凝胶(Sol-Gel)和两步氢还原及烧结法成功制备了(2%～5%),质量分数,下同)La2O3-Mo阴极粉末和烧结体,借助于XRD,SEM等手段对材料成分及微观结构进行分析.结果显示在粉末和烧结体中稀土元素La以氧化物形式存在,La2O3粒子大小为100nm,弥散分布在烧结体基体中.热发射测试结果表明1400℃时,零场发射电流达到J0=6A/cm^2.暴露大气48h后,再经过1350℃激活,发射性能得到全面恢复.
采用溶胶凝胶(Sol-Gel)和两步氢还原及烧结法成功制备了(2%～5%),质量分数,下同)La2O3-Mo阴极粉末和烧结体,借助于XRD,SEM等手段对材料成分及微观结构进行分析.结果显示在粉末和烧结体中稀土元素La以氧化物形式存在,La2O3粒子大小为100nm,弥散分布在烧结体基体中.热发射测试结果表明1400℃时,零场发射电流达到J0=6A/cm^2.暴露大气48h后,再经过1350℃激活,发射性能得到全面恢复.
2005, 34(3):471-474.
Abstract:
商业用纯钛在空气炉中700℃～900℃,1h～4h进行热氧化处理,得到由氧化层和渗氧层构成的表面结构.通过金相观察、显微硬度测试、X射线衍射(XRD)及扫描电镜(SEM)分析,研究了渗氧层的结构和性能.结果表明,经一定温度及时间处理,试样渗氧层被一条连续的界线分为内渗氧层和外渗氧层,在光学显微镜下观察,内外两层渗氧层形貌无差别,但在扫描电镜下观察可发现在较高温度形成的外渗氧层较疏松,内渗氧层则仍致密.随着热处理温度的升高、时间的延长,渗氧层厚度和含氧量增加,晶格常数c伸长,表面硬度显著增大.
商业用纯钛在空气炉中700℃～900℃,1h～4h进行热氧化处理,得到由氧化层和渗氧层构成的表面结构.通过金相观察、显微硬度测试、X射线衍射(XRD)及扫描电镜(SEM)分析,研究了渗氧层的结构和性能.结果表明,经一定温度及时间处理,试样渗氧层被一条连续的界线分为内渗氧层和外渗氧层,在光学显微镜下观察,内外两层渗氧层形貌无差别,但在扫描电镜下观察可发现在较高温度形成的外渗氧层较疏松,内渗氧层则仍致密.随着热处理温度的升高、时间的延长,渗氧层厚度和含氧量增加,晶格常数c伸长,表面硬度显著增大.
2005, 34(3):475-478.
Abstract:
Nano-metal nickel powder is prepared by liberty arc in which fusible hydrogen is joined as cathode shoot. It is found that the influence of working pressure do not followed the classical rules. Hydrogen is a key factor to improve the productive efficiency of nano metal powder. The mini-hydrogen bubble in fusible metal can lead to the vacuum evaporating of Nickel, so the powder productivity is proportional to the hydrogen pressure. The molecular evaporating mechanism of hydrogen in Ni bubble is presented.
Nano-metal nickel powder is prepared by liberty arc in which fusible hydrogen is joined as cathode shoot. It is found that the influence of working pressure do not followed the classical rules. Hydrogen is a key factor to improve the productive efficiency of nano metal powder. The mini-hydrogen bubble in fusible metal can lead to the vacuum evaporating of Nickel, so the powder productivity is proportional to the hydrogen pressure. The molecular evaporating mechanism of hydrogen in Ni bubble is presented.
2005, 34(3):479-482.
Abstract:
采用Gleeble-1500D热模拟机,在电场和大热流密度作用下,研究压坯密度对55%(Ti C)-45?(质量分数)粉末压坯低温燃烧合成过程的影响.结果表明:当压坯密度在68%～78%范围内,体系的点火温度在340℃～650℃之间;随压坯密度提高,体系点火温度降低,点火延迟时间缩短,所达到的最高温度也降低.同时,合成产物的XRD结果表明:较低密度压坯的合成反应进行完全,而过高的压坯密度会导致合成反应的不完全性.
采用Gleeble-1500D热模拟机,在电场和大热流密度作用下,研究压坯密度对55%(Ti C)-45?(质量分数)粉末压坯低温燃烧合成过程的影响.结果表明:当压坯密度在68%～78%范围内,体系的点火温度在340℃～650℃之间;随压坯密度提高,体系点火温度降低,点火延迟时间缩短,所达到的最高温度也降低.同时,合成产物的XRD结果表明:较低密度压坯的合成反应进行完全,而过高的压坯密度会导致合成反应的不完全性.
2005, 34(3):483-485.
Abstract:
研究了1种新型的纳米AgSnO2触头材料.通过采用掺杂、SnO2粒子的纳米化及化学镀的方法,改善了氧化物和银的浸润性,从而提高了触头材料的导电性、机械强度和加工性能.通过机械混合法和溶胶凝胶法2种工艺的对比,证明用机械混合法在SnO2中掺杂TiO2,反而使电导率升高;用溶胶凝胶法在SnO2中掺杂TiO2,Ti4 能够很好的进入SnO2的晶格,能够明显改善触头的电性能.微观组织分析表明:纳米触头中SnO2的分布明显的比非纳米触头中SnO2分布的要均匀,从而可以避免因SnO2的富集导致电导率降低,提高AgSnO2触头的电性能和电寿命.
研究了1种新型的纳米AgSnO2触头材料.通过采用掺杂、SnO2粒子的纳米化及化学镀的方法,改善了氧化物和银的浸润性,从而提高了触头材料的导电性、机械强度和加工性能.通过机械混合法和溶胶凝胶法2种工艺的对比,证明用机械混合法在SnO2中掺杂TiO2,反而使电导率升高;用溶胶凝胶法在SnO2中掺杂TiO2,Ti4 能够很好的进入SnO2的晶格,能够明显改善触头的电性能.微观组织分析表明:纳米触头中SnO2的分布明显的比非纳米触头中SnO2分布的要均匀,从而可以避免因SnO2的富集导致电导率降低,提高AgSnO2触头的电性能和电寿命.
2005, 34(3):486-488.
Abstract:
用放电等离子烧结技术将WO3和炭黑的混合粉原位合成为致密的WC块体.研究了合成工艺和配碳量对块体的物相、致密度和显微组织的影响,结果表明:在860℃～1060℃温度范围内,炭能快速地将WO3还原成W,同时发生碳化反应,温度继续升高发生烧结.含碳量低时,块体中有杂相W或W2C,含碳量合适时,块体的物相为纯WC,致密度达到WC的理论密度,晶粒在500nm左右.
用放电等离子烧结技术将WO3和炭黑的混合粉原位合成为致密的WC块体.研究了合成工艺和配碳量对块体的物相、致密度和显微组织的影响,结果表明:在860℃～1060℃温度范围内,炭能快速地将WO3还原成W,同时发生碳化反应,温度继续升高发生烧结.含碳量低时,块体中有杂相W或W2C,含碳量合适时,块体的物相为纯WC,致密度达到WC的理论密度,晶粒在500nm左右.
2005, 34(3):489-492.
Abstract:
Sintering is one of the most important steps for powder metallurgy (PM). In order to observe the sintering process directly, a high temperature optical microscope (HTOM) was used to in-situ investigate the Al and Mg binary alloy system with a weight ratio of 9:1. A typical physical evolving character was found in this system. The melting process of magnesium particles is not synchronous, first from the particle border, then in the grain boundary, and last into the whole magnesium particle. When sintering temperature is above a critical temperature Tc, the magnesium particle melts in a very short time, and the sintering rate is accelerated with the increasing of the cold compact density. These experiment results afford a direct reference to the sintering routine optimization.
Sintering is one of the most important steps for powder metallurgy (PM). In order to observe the sintering process directly, a high temperature optical microscope (HTOM) was used to in-situ investigate the Al and Mg binary alloy system with a weight ratio of 9:1. A typical physical evolving character was found in this system. The melting process of magnesium particles is not synchronous, first from the particle border, then in the grain boundary, and last into the whole magnesium particle. When sintering temperature is above a critical temperature Tc, the magnesium particle melts in a very short time, and the sintering rate is accelerated with the increasing of the cold compact density. These experiment results afford a direct reference to the sintering routine optimization.
2005, 34(3):493-496.
Abstract:
Research about the 91tungsten alloy deformed by hydrostatic extrusion is carried out. The relations between the microstructures, mechanical properties of the 91tungsten alloy after deformation and the deformation amount were studied. The results show that the ratio of the long-short axis of tungsten particles and the strength of tungsten alloys increase along with the increase of the deformation amount, the valid contiguity of tungsten particles and the elongation ratio and contraction ratio of area of tungsten alloys decrease along with the increase of the deformation amount. Both the increment and the decrement become smaller and smaller along with the increase of the hydrostatic extrusion deformation amount.
Research about the 91tungsten alloy deformed by hydrostatic extrusion is carried out. The relations between the microstructures, mechanical properties of the 91tungsten alloy after deformation and the deformation amount were studied. The results show that the ratio of the long-short axis of tungsten particles and the strength of tungsten alloys increase along with the increase of the deformation amount, the valid contiguity of tungsten particles and the elongation ratio and contraction ratio of area of tungsten alloys decrease along with the increase of the deformation amount. Both the increment and the decrement become smaller and smaller along with the increase of the hydrostatic extrusion deformation amount.
2005, 34(3):497-500.
Abstract:
根据合金相图的基本原理,分析了Au-Ag-Si系相图,研制出熔化温度在400℃～500℃的共晶钎料合金.通过钎料合金与Ni板的润湿性测试和润湿后界面的微观组织分析.结果表明:Au-Ag-Si系钎料对于纯Ni具有良好的漫流性和润湿性,在450℃～500℃范围内,可以对Ni板进行钎焊.
根据合金相图的基本原理,分析了Au-Ag-Si系相图,研制出熔化温度在400℃～500℃的共晶钎料合金.通过钎料合金与Ni板的润湿性测试和润湿后界面的微观组织分析.结果表明:Au-Ag-Si系钎料对于纯Ni具有良好的漫流性和润湿性,在450℃～500℃范围内,可以对Ni板进行钎焊.
2005, 34(3):501-504.
Abstract:
研究激光退火对Inconel718时效合金的显微组织和硬度的影响.一台2.5kW的CO2激光机被用来照射试样的表面.在激光能作用下,试样表面层被加热后空冷.通过控制激光工艺参数,在表面不发生熔化的前提下,能够使一定厚度表面层内的硬度降低到标准退火合金的水平,而不影响试样内部母材的硬度.显微组织观察显示表面层的基体强化相(γ″和γ‘)在激光照射过程中被固溶,而其它二次相没有变化.γ″和γ‘的固溶被确定是表面层硬度下降的原因.在其它试验条件不变时,确立了退火层生成时由激光散焦距离和扫描速度描述的工艺参数范围.
研究激光退火对Inconel718时效合金的显微组织和硬度的影响.一台2.5kW的CO2激光机被用来照射试样的表面.在激光能作用下,试样表面层被加热后空冷.通过控制激光工艺参数,在表面不发生熔化的前提下,能够使一定厚度表面层内的硬度降低到标准退火合金的水平,而不影响试样内部母材的硬度.显微组织观察显示表面层的基体强化相(γ″和γ‘)在激光照射过程中被固溶,而其它二次相没有变化.γ″和γ‘的固溶被确定是表面层硬度下降的原因.在其它试验条件不变时,确立了退火层生成时由激光散焦距离和扫描速度描述的工艺参数范围.
