Volume 35,Issue 7,2006 Table of Contents
2006, 35(7):1009-1016.
Abstract:
将Zr-4和成分接近ZIRLO的3#合金样品置于高压釜中,经过360℃,18.6 MPa的0.01 mol/L LiOH水溶液腐蚀1 50 d后,增重分别达到310 mg/dm^2和82 mg/dm^2,3#合金的耐腐蚀性能明显优于Zr-4.用透射电镜、扫描电镜和扫描探针显微镜研究了两种样品经过70 d和150 d腐蚀后,氧化膜不同深度处的显微组织和晶体结构;研究了氧化膜的断口形貌和氧化膜的表面形貌.结果表明：Zr-4氧化膜中的空位比3#合金氧化膜中的更容易通过扩散凝聚形成孔洞簇和晶界微裂纹,也容易发展成平行于氧化膜/金属界面的裂纹,导致腐蚀转折提早发生,这与Li^＋和OH^-渗入氧化膜后降低氧化锆表面自由能的程度有关.从氧化膜表面晶粒形貌判断,Zr-4样品形成氧化锆后的表面自由能比3#合金样品形成氧化锆后的低,这是合金成分不同引起的一种差异,也可能是Zr-4样品在LiOH水溶液中的耐腐蚀性能比3#样品差的一个重要原因.
将Zr-4和成分接近ZIRLO的3#合金样品置于高压釜中,经过360℃,18.6 MPa的0.01 mol/L LiOH水溶液腐蚀1 50 d后,增重分别达到310 mg/dm^2和82 mg/dm^2,3#合金的耐腐蚀性能明显优于Zr-4.用透射电镜、扫描电镜和扫描探针显微镜研究了两种样品经过70 d和150 d腐蚀后,氧化膜不同深度处的显微组织和晶体结构;研究了氧化膜的断口形貌和氧化膜的表面形貌.结果表明：Zr-4氧化膜中的空位比3#合金氧化膜中的更容易通过扩散凝聚形成孔洞簇和晶界微裂纹,也容易发展成平行于氧化膜/金属界面的裂纹,导致腐蚀转折提早发生,这与Li^＋和OH^-渗入氧化膜后降低氧化锆表面自由能的程度有关.从氧化膜表面晶粒形貌判断,Zr-4样品形成氧化锆后的表面自由能比3#合金样品形成氧化锆后的低,这是合金成分不同引起的一种差异,也可能是Zr-4样品在LiOH水溶液中的耐腐蚀性能比3#样品差的一个重要原因.
2006, 35(7):1017-1020.
Abstract:
Zr-Al-Ni-Fe alloy series with different compositions were designed according to the criteria of constant electron concentration and atomic size. XRD results indicate that only the four alloys near the Zr-Al-Ni ternary system formed the bulk metallic glass. It is revealed by DSC and DTA curves that the best composition forming glass is Zr60.7Al15.5Ni15.5Fe8.3 with the thermodynamic characteristic parameters of Tg=710 K, Tx=770 K, ?Tx=60 K, Tg/Tm=0.607, and Tg/Tl=0.552, respectively.
Zr-Al-Ni-Fe alloy series with different compositions were designed according to the criteria of constant electron concentration and atomic size. XRD results indicate that only the four alloys near the Zr-Al-Ni ternary system formed the bulk metallic glass. It is revealed by DSC and DTA curves that the best composition forming glass is Zr60.7Al15.5Ni15.5Fe8.3 with the thermodynamic characteristic parameters of Tg=710 K, Tx=770 K, ?Tx=60 K, Tg/Tm=0.607, and Tg/Tl=0.552, respectively.
2006, 35(7):1021-1024.
Abstract:
采用化学共沉淀法掺金属Nb,Ta和P到ITO材料中可使ITO(IndiumTinOxide)靶相对密度达到97%~99%,并且靶电阻率小于3.0×10-4??cm,其质量损失率小于4.0%。采用直接掺杂法将TiO2纳米粉末掺入到纳米ITO粉末中可使ITO靶相对密度达到95%以上。当烧结温度为l500℃时,掺Nb,Ta,P的ITO靶电阻率稍小于纯ITO靶的电阻率。
采用化学共沉淀法掺金属Nb,Ta和P到ITO材料中可使ITO(IndiumTinOxide)靶相对密度达到97%~99%,并且靶电阻率小于3.0×10-4??cm,其质量损失率小于4.0%。采用直接掺杂法将TiO2纳米粉末掺入到纳米ITO粉末中可使ITO靶相对密度达到95%以上。当烧结温度为l500℃时,掺Nb,Ta,P的ITO靶电阻率稍小于纯ITO靶的电阻率。
2006, 35(7):1025-1029.
Abstract:
A mechanical analytical model is put forward for the three-dimensional isotropic reticulated porous metals under biaxial tension according to a simplified structural model in this study. The relationship between biaxial nominal stresses and porosity at the beginning of breakdown is derived for these materials from this analytical model. Based on the resultant relationship, the safety criterion can be further obtained for these foamed metals under biaxial loading. When the biaxial nominal stresses are equal to each other, the mathematical relationship between loading strength and porosity can be also gained for the foamed metals under biaxial equal loads. According to the typical experiment on nickel foam as an example, it is proved that these theoretical formulas well accorded with the practical ones. The safety criterion for the porous bodies under biaxial loading can be gotten from this model, which is not dealt with or difficult to do by other relative theories, such as Gibson-Ashby model.
A mechanical analytical model is put forward for the three-dimensional isotropic reticulated porous metals under biaxial tension according to a simplified structural model in this study. The relationship between biaxial nominal stresses and porosity at the beginning of breakdown is derived for these materials from this analytical model. Based on the resultant relationship, the safety criterion can be further obtained for these foamed metals under biaxial loading. When the biaxial nominal stresses are equal to each other, the mathematical relationship between loading strength and porosity can be also gained for the foamed metals under biaxial equal loads. According to the typical experiment on nickel foam as an example, it is proved that these theoretical formulas well accorded with the practical ones. The safety criterion for the porous bodies under biaxial loading can be gotten from this model, which is not dealt with or difficult to do by other relative theories, such as Gibson-Ashby model.
5 Simulation of the Precipitation Process of Ni75Al5.5V19.5 Alloy Using Microscopic Phase-Field Method
2006, 35(7):1030-1034.
Abstract:
The precipitation processes of the ordered phases D022 and L1 2 in Ni75Al5.5V19.5 alloy at different temperatures were studied using the microscopic phase-field method. It is found that the supercooling degree is the main factor for the phase transformation. The D022 phase precipitates at a higher temperature firstly, then the L1 2 phase precipitates at the phase boundaries of D022 and disordered phases and round the interphase of D022 forming. The L1 2 phase grew towards the disordered matrix and the D022 phase nearly at the same time. Then at a lower temperature, the L1 2 phase precipitates firstly, then the D022 phase precipitates at the ordered interphase of L1 2 phase, which transforms from a nonstoichiometric phase to a equilibrium phase through spinodal decomposition and the dimension becomes smaller. The volume fractions of the two phases are almost equal at last. With the temperature decreasing, the precipitation mechanism of L1 2 phase transforms from the mixed pattern of non-classical nucleation and spinodal decomposition of higher temperature to the spinodal decomposition of lower temperature, but the precipitation mechanism of D022 phase transforms from the mixed pattern to the non-classical nucleation.
The precipitation processes of the ordered phases D022 and L1 2 in Ni75Al5.5V19.5 alloy at different temperatures were studied using the microscopic phase-field method. It is found that the supercooling degree is the main factor for the phase transformation. The D022 phase precipitates at a higher temperature firstly, then the L1 2 phase precipitates at the phase boundaries of D022 and disordered phases and round the interphase of D022 forming. The L1 2 phase grew towards the disordered matrix and the D022 phase nearly at the same time. Then at a lower temperature, the L1 2 phase precipitates firstly, then the D022 phase precipitates at the ordered interphase of L1 2 phase, which transforms from a nonstoichiometric phase to a equilibrium phase through spinodal decomposition and the dimension becomes smaller. The volume fractions of the two phases are almost equal at last. With the temperature decreasing, the precipitation mechanism of L1 2 phase transforms from the mixed pattern of non-classical nucleation and spinodal decomposition of higher temperature to the spinodal decomposition of lower temperature, but the precipitation mechanism of D022 phase transforms from the mixed pattern to the non-classical nucleation.
2006, 35(7):1035-1038.
Abstract:
Arc-glow plasma depositing technique is a new surface coating method. With the help of vacuum arc discharge, a cold cathode arc source continually emits ion beams of coating elements with high currency density and high ionizing ratio. Upon the ion bombard and diffusion work on, the surfaces of the parts form deposited layers, diffusion layers. In this study, a commercial magnesium alloy AZ91 was coated with Ti film layer. The corrosion behaviors of the coated samples have been studied by methods of measuring anodic polarization curves and salt spray test. Section and surface morphology of Ti film have been surveyed through scanning electronic microscopy (SEM), the composition analyzed by electron diffraction spectrum (EDS) and glow discharge spectrum (GDS). The results indicated that the coating of Ti effectively improved the anti-corrosion performance of AZ91.
Arc-glow plasma depositing technique is a new surface coating method. With the help of vacuum arc discharge, a cold cathode arc source continually emits ion beams of coating elements with high currency density and high ionizing ratio. Upon the ion bombard and diffusion work on, the surfaces of the parts form deposited layers, diffusion layers. In this study, a commercial magnesium alloy AZ91 was coated with Ti film layer. The corrosion behaviors of the coated samples have been studied by methods of measuring anodic polarization curves and salt spray test. Section and surface morphology of Ti film have been surveyed through scanning electronic microscopy (SEM), the composition analyzed by electron diffraction spectrum (EDS) and glow discharge spectrum (GDS). The results indicated that the coating of Ti effectively improved the anti-corrosion performance of AZ91.
2006, 35(7):1039-1044.
Abstract:
Energy deposition at the interface of the particles caused by micro-explosive welding in explosive consolidation of metal powders is analyzed by symmetrical impaction model of uncompressible liquid. Two-dimensional equation of energy in the flow field of explosive welding is deduced and solved by finite difference method. Then the distribution of the temperature in the flow field is calculated on the basis of considering the adiabatic compression. The results show that under an appropriate pressure the temperature rise near the welding interface caused by micro-explosive welding in explosive consolidation of metal powders will be higher than the melting point of the materials, and the thin melted layers are localized on the surfaces of the particles, the temperature rise increases with increasing of approaching flow velocity and impact angle.
Energy deposition at the interface of the particles caused by micro-explosive welding in explosive consolidation of metal powders is analyzed by symmetrical impaction model of uncompressible liquid. Two-dimensional equation of energy in the flow field of explosive welding is deduced and solved by finite difference method. Then the distribution of the temperature in the flow field is calculated on the basis of considering the adiabatic compression. The results show that under an appropriate pressure the temperature rise near the welding interface caused by micro-explosive welding in explosive consolidation of metal powders will be higher than the melting point of the materials, and the thin melted layers are localized on the surfaces of the particles, the temperature rise increases with increasing of approaching flow velocity and impact angle.
2006, 35(7):1045-1049.
Abstract:
采用熔盐电解法,在900℃熔盐CaCl2中以烧结TiO2为阴极,石墨棒为阳极制备出了金属钛.研究了不同温度下烧结阴极的形貌及其对电解反应的影响.结果表明：600℃下烧结4 h的阴极具有良好电化学反应性能;电解过程中脱氧速度不均匀;TiO2电极的还原是由外向内,由高价向低价再到金属分步进行的;电解还原过程电流效率低约为15%.阴极的孔隙大小和颗粒尺寸会影响电极的反应速度.
采用熔盐电解法,在900℃熔盐CaCl2中以烧结TiO2为阴极,石墨棒为阳极制备出了金属钛.研究了不同温度下烧结阴极的形貌及其对电解反应的影响.结果表明：600℃下烧结4 h的阴极具有良好电化学反应性能;电解过程中脱氧速度不均匀;TiO2电极的还原是由外向内,由高价向低价再到金属分步进行的;电解还原过程电流效率低约为15%.阴极的孔隙大小和颗粒尺寸会影响电极的反应速度.
2006, 35(7):1050-1052.
Abstract:
The fretting fatigue behavior of TC4 titanium alloy was investigated using a cylinder-plane configuration. Through the observation of worn surface and cross-section, the formation and evolving process of the fretting debris and the effects during fretting fatigue were discussed. The variation of friction coefficient with time was analyzed. Based on the experimental results of TC4 titanium alloy, it is found that the damage mechanism of fretting fatigue was adhering wear, abrasive wear and contact fatigue, accompanying with oxidation wear. The fretting debris were formed from the break-off and crushing of the parent alloy, then oxidization to be the fragments during the fretting fatigue test. It promoted the abrasive wear and accelerated the fatigue failure due to the hard oxide particles in fretting debris. The friction coefficient rapidly increased with time in the initial stage, then kept stable in the stable stage.
The fretting fatigue behavior of TC4 titanium alloy was investigated using a cylinder-plane configuration. Through the observation of worn surface and cross-section, the formation and evolving process of the fretting debris and the effects during fretting fatigue were discussed. The variation of friction coefficient with time was analyzed. Based on the experimental results of TC4 titanium alloy, it is found that the damage mechanism of fretting fatigue was adhering wear, abrasive wear and contact fatigue, accompanying with oxidation wear. The fretting debris were formed from the break-off and crushing of the parent alloy, then oxidization to be the fragments during the fretting fatigue test. It promoted the abrasive wear and accelerated the fatigue failure due to the hard oxide particles in fretting debris. The friction coefficient rapidly increased with time in the initial stage, then kept stable in the stable stage.
2006, 35(7):1053-1056.
Abstract:
采用离子渗镀技术在Ti6Al4V合金表面形成均匀致密的钼氮陶瓷渗镀层,对陶瓷层微动摩擦学性能进行研究.100000周次微动磨损试验结果表明,渗镀的Mo-N陶瓷层显著提高了Ti6A14V合金的抗微动磨损能力.Ti6Al4V合金微动磨损机制是粘着与磨粒磨损的综合效应,Mo-N陶瓷层微动磨损机制是犁削.
采用离子渗镀技术在Ti6Al4V合金表面形成均匀致密的钼氮陶瓷渗镀层,对陶瓷层微动摩擦学性能进行研究.100000周次微动磨损试验结果表明,渗镀的Mo-N陶瓷层显著提高了Ti6A14V合金的抗微动磨损能力.Ti6Al4V合金微动磨损机制是粘着与磨粒磨损的综合效应,Mo-N陶瓷层微动磨损机制是犁削.
2006, 35(7):1057-1060.
Abstract:
Silver foils irradiated by atomic oxygen (AO) generated in a ground simulation facility were investigated by quartz crystal microbalance (QCM), scanning electron microscopy (SEM) and X-ray Diffraction (XRD). The experimental results show that the oxidation behaviour of silver foil exposed to AO exhibits two stages: forming a thick Ag2O film at first, then forming AgO in the upper layer of the oxide film by the reaction of Ag2O film with O. At the first stage, the oxide layer cracked and spalled due to the development of stresses, so that new silver surface exposed out, and the further fast oxidation happened.
Silver foils irradiated by atomic oxygen (AO) generated in a ground simulation facility were investigated by quartz crystal microbalance (QCM), scanning electron microscopy (SEM) and X-ray Diffraction (XRD). The experimental results show that the oxidation behaviour of silver foil exposed to AO exhibits two stages: forming a thick Ag2O film at first, then forming AgO in the upper layer of the oxide film by the reaction of Ag2O film with O. At the first stage, the oxide layer cracked and spalled due to the development of stresses, so that new silver surface exposed out, and the further fast oxidation happened.
2006, 35(7):1061-1064.
Abstract:
Ti-Fe-Cr-Ni-C composite coatings were deposited with a new process of Reactive Flame Spray (RFS) from the powders synthesized by the process of precursor-carbonization-composite, in which ferrotitanium and asphalt were used as raw materials. XRD and SEM were employed to analyze the phase composition and microstructure of the composite powders and coatings. The wear resistance of the coating was tested. The results show that the TiC/FeCrNi composite coating by RFS is composed of layers in which the round nanoscale TiC particles are dispersed within a metal matrix. The matrix consists of Cr0.19Fe0.7Ni0.11 and (Fe, Cr). Under the same condition of wear testing, the wear volume of the TiC/FeCrNi composite coating is one eighth of that of the Ni60 coating by normal flame spray.
Ti-Fe-Cr-Ni-C composite coatings were deposited with a new process of Reactive Flame Spray (RFS) from the powders synthesized by the process of precursor-carbonization-composite, in which ferrotitanium and asphalt were used as raw materials. XRD and SEM were employed to analyze the phase composition and microstructure of the composite powders and coatings. The wear resistance of the coating was tested. The results show that the TiC/FeCrNi composite coating by RFS is composed of layers in which the round nanoscale TiC particles are dispersed within a metal matrix. The matrix consists of Cr0.19Fe0.7Ni0.11 and (Fe, Cr). Under the same condition of wear testing, the wear volume of the TiC/FeCrNi composite coating is one eighth of that of the Ni60 coating by normal flame spray.
2006, 35(7):1065-1070.
Abstract:
Using a first-principle pseudopotential plane-wave method, the energetic, geometrical and electronic structures of point defects are calculated for B2-RuAl intermetallic compound. Based on the calculation and comparison of the formation heat and formation energy for several kinds of point defective structures, the type and the geometrical configuration of point defects in B2-RuAl intermetallic compound are analyzed and forecasted. Results show that the major point defects in B2-RuAl intermetallic compound are vacancy or anti-site in the Ru sublattice, i.e., Ru vacancy and Al anti-site, but mainly Ru anti-site defect in rich-Ru alloy, and mostly Al anti-site defect in rich-Al alloy. These point defects emerge in the form of Ru-Ru double vacancy or Al-Al double anti-site configurations, namely, there are two vacancies or two Al atoms in the Ru sublattice. And they would be in the most stable structure when the double vacancies at Ru sites were in the first nearest neighborhood, or when the double Al atoms at Ru sites were in the third nearest neighborhood. In addition, the influences of above point defects on Cauchy pressre parameter(C12-C44)of B2-RuAl and NiAl were also compared. It is found that the decreasing of C12-C44 caused by point defects in RuAl is smaller than that in NiAl, so that the ductility of RuAl metallic compound with point defects at room temperature is better than NiAl.
Using a first-principle pseudopotential plane-wave method, the energetic, geometrical and electronic structures of point defects are calculated for B2-RuAl intermetallic compound. Based on the calculation and comparison of the formation heat and formation energy for several kinds of point defective structures, the type and the geometrical configuration of point defects in B2-RuAl intermetallic compound are analyzed and forecasted. Results show that the major point defects in B2-RuAl intermetallic compound are vacancy or anti-site in the Ru sublattice, i.e., Ru vacancy and Al anti-site, but mainly Ru anti-site defect in rich-Ru alloy, and mostly Al anti-site defect in rich-Al alloy. These point defects emerge in the form of Ru-Ru double vacancy or Al-Al double anti-site configurations, namely, there are two vacancies or two Al atoms in the Ru sublattice. And they would be in the most stable structure when the double vacancies at Ru sites were in the first nearest neighborhood, or when the double Al atoms at Ru sites were in the third nearest neighborhood. In addition, the influences of above point defects on Cauchy pressre parameter(C12-C44)of B2-RuAl and NiAl were also compared. It is found that the decreasing of C12-C44 caused by point defects in RuAl is smaller than that in NiAl, so that the ductility of RuAl metallic compound with point defects at room temperature is better than NiAl.
2006, 35(7):1071-1074.
Abstract:
对一种加3%～5%（质量分数）金属Re的CoNiCrAly合金在1000℃空气中进行了恒温氧化实验,利用X射线衍射、扫描电镜和能谱分析研究其氧化行为.结果表明：与不加Re的合金相比,加Re合金在初期氧化阶段增重较低;并且金属Re加速了亚稳过渡相θ-Al2O3向稳定相α-Al2O3的转变,有利于快速生成致密的α-Al2O3保护膜.
对一种加3%～5%（质量分数）金属Re的CoNiCrAly合金在1000℃空气中进行了恒温氧化实验,利用X射线衍射、扫描电镜和能谱分析研究其氧化行为.结果表明：与不加Re的合金相比,加Re合金在初期氧化阶段增重较低;并且金属Re加速了亚稳过渡相θ-Al2O3向稳定相α-Al2O3的转变,有利于快速生成致密的α-Al2O3保护膜.
15 Friction Characteristics between U-Nb Alloy and Film by Ion Beam Deposition on Ta12W Alloy Surface
2006, 35(7):1075-1079.
Abstract:
Sn and In soft metal films, Al2O3 ceramic film and In/Al2O3 dual film were prepared with ion beam deposition technique. Sliding friction characteristics of these films against U-Nb alloy pin were evaluated by a pin-disc tribometer and Scan Electrical Microscopy (SEM). It had been found that the friction coefficients of sliding against SiC ceramics ball with smoothing surface decreased for the Sn and In films due to their very low strength, but increased against U-Nb alloy pin with engineering-coarse surface for the In film and In/Al2O3 dual film due to the adhesion between In and U-Nb alloy. Meantime, very thin Sn film resulted in increase of friction coefficient. The friction property would be improved only when the thickness of Sn film increased to a reasonable value. Otherwise, the friction coefficient of Al2O3 ceramics film against the U-Nb alloy with low strength did not decrease almost same as the results of Ta12W alloy because the U-Nb alloy was easy to be worn and transferred on the surface.
Sn and In soft metal films, Al2O3 ceramic film and In/Al2O3 dual film were prepared with ion beam deposition technique. Sliding friction characteristics of these films against U-Nb alloy pin were evaluated by a pin-disc tribometer and Scan Electrical Microscopy (SEM). It had been found that the friction coefficients of sliding against SiC ceramics ball with smoothing surface decreased for the Sn and In films due to their very low strength, but increased against U-Nb alloy pin with engineering-coarse surface for the In film and In/Al2O3 dual film due to the adhesion between In and U-Nb alloy. Meantime, very thin Sn film resulted in increase of friction coefficient. The friction property would be improved only when the thickness of Sn film increased to a reasonable value. Otherwise, the friction coefficient of Al2O3 ceramics film against the U-Nb alloy with low strength did not decrease almost same as the results of Ta12W alloy because the U-Nb alloy was easy to be worn and transferred on the surface.
2006, 35(7):1080-1084.
Abstract:
利用键参数函数和尺寸因数对第四长周期过渡族金属元素基准晶形成规律进行研究。发现可以用抛物线y=a-bx^2将准晶形成区与准晶不能形成区区分开，准晶形成区的准确率达到了93．12％。同时，发现抛物线的参数a，b可以由基体元素的相关参数确定，即a∝E,b∝EμR0^3.
利用键参数函数和尺寸因数对第四长周期过渡族金属元素基准晶形成规律进行研究。发现可以用抛物线y=a-bx^2将准晶形成区与准晶不能形成区区分开，准晶形成区的准确率达到了93．12％。同时，发现抛物线的参数a，b可以由基体元素的相关参数确定，即a∝E,b∝EμR0^3.
2006, 35(7):1085-1088.
Abstract:
利用XRD,SEM和EDX对石墨表面钛金属化界面的物相、微观组织及成分进行了分析.结果表明,金属化石墨微观组织呈层状结构,依次为内层（石墨）、过渡层、致密层及外层（Ti）,其中过渡层厚约为720 μm,致密层厚约为40 μm.XRD及EDX分析证实了致密层物相为碳化钛,SEM分析证实了致密层与过渡层及Ti层结合牢固.但还发现在Ti层与致密层界面处存在短微裂纹,在致密层与过渡层界面处未有发现,原因主要是材料间的热膨胀系数差异产生热应力所致.并且还对石墨表面金属化机理进行了探讨.研究表明,其机理是通过金属Ti与石墨发生界面反应生成碳化钛来实现.
利用XRD,SEM和EDX对石墨表面钛金属化界面的物相、微观组织及成分进行了分析.结果表明,金属化石墨微观组织呈层状结构,依次为内层（石墨）、过渡层、致密层及外层（Ti）,其中过渡层厚约为720 μm,致密层厚约为40 μm.XRD及EDX分析证实了致密层物相为碳化钛,SEM分析证实了致密层与过渡层及Ti层结合牢固.但还发现在Ti层与致密层界面处存在短微裂纹,在致密层与过渡层界面处未有发现,原因主要是材料间的热膨胀系数差异产生热应力所致.并且还对石墨表面金属化机理进行了探讨.研究表明,其机理是通过金属Ti与石墨发生界面反应生成碳化钛来实现.
18 Obvious Difference in Fracture Strength and Magnetic Properties by Strip Casting Thickness of NdFeB
2006, 35(7):1089-1091.
Abstract:
研究了烧结NdFeB磁体强韧性和磁性能对速凝铸带厚度的依赖性.结果表明：磁体的抗弯强度随着铸带厚度的减小而迅速增大,当铸带较薄时,带内的微细晶制粉时形成较多氧化的细小颗粒,它们能有效延缓烧结过程中的晶粒生长速度.由断裂强度公式得知,晶粒越小,磁体抗弯强度越高,因此用0.38 mm厚铸带制成的磁体抗弯强度比0.45mm厚铸带制成的磁体大得多.同时,铸带厚度为0.45 mm时,带内晶粒尺寸分布较好（3 μm～5μm）,此厚度铸带制备的磁体磁性能可获得最佳值.
研究了烧结NdFeB磁体强韧性和磁性能对速凝铸带厚度的依赖性.结果表明：磁体的抗弯强度随着铸带厚度的减小而迅速增大,当铸带较薄时,带内的微细晶制粉时形成较多氧化的细小颗粒,它们能有效延缓烧结过程中的晶粒生长速度.由断裂强度公式得知,晶粒越小,磁体抗弯强度越高,因此用0.38 mm厚铸带制成的磁体抗弯强度比0.45mm厚铸带制成的磁体大得多.同时,铸带厚度为0.45 mm时,带内晶粒尺寸分布较好（3 μm～5μm）,此厚度铸带制备的磁体磁性能可获得最佳值.
2006, 35(7):1092-1095.
Abstract:
采用共沉淀BaTiO3为基,适量掺杂Nd2O3稀土氧化物及MgO与ZnO添加剂,获得具有X7R温度特性的低频高压MLC瓷料系统,BaTiO3基瓷的平均晶粒尺寸小于0.8μm,居里点弥散成为居里区.其介电性能为介电系数ε≥3000;容量变化率△C/C≤±15%;介电损耗tgδ≤120×10-4;体积电阻率ρv≥1012Ω·cm;击穿场强Eb≥15 kV/mm.
采用共沉淀BaTiO3为基,适量掺杂Nd2O3稀土氧化物及MgO与ZnO添加剂,获得具有X7R温度特性的低频高压MLC瓷料系统,BaTiO3基瓷的平均晶粒尺寸小于0.8μm,居里点弥散成为居里区.其介电性能为介电系数ε≥3000;容量变化率△C/C≤±15%;介电损耗tgδ≤120×10-4;体积电阻率ρv≥1012Ω·cm;击穿场强Eb≥15 kV/mm.
2006, 35(7):1096-1100.
Abstract:
Bioactive calcium phosphate coatings on carbon/carbon composites were prepared by a cathode sonoelectrodepostion technique. The effects of electrodeposition time on the morphology, structure and composition of the coatings on carbon/carbon composites were investigated by SEM, EDAX, FTIR and XRD. The experimental results show that the plate-like crystals formed in initial stages of electrodeposition were identified to be CaHPO4.2H2O(DCPD). With the electrodeposition time elapsing, the formed needle-like precipitates were identified to be Ca10(PO4)6(OH)2(HA), the coating thickness and the n(Ca)/n(P) ratio increased continuously. The degree of crystallization of the coatings and the pH values of electrolyte decreased with the electrodeposition time increasing. The coatings were calcium-deficient apatite. In addition, the growth mechanism of coatings on C/C composites was also discussed.
Bioactive calcium phosphate coatings on carbon/carbon composites were prepared by a cathode sonoelectrodepostion technique. The effects of electrodeposition time on the morphology, structure and composition of the coatings on carbon/carbon composites were investigated by SEM, EDAX, FTIR and XRD. The experimental results show that the plate-like crystals formed in initial stages of electrodeposition were identified to be CaHPO4.2H2O(DCPD). With the electrodeposition time elapsing, the formed needle-like precipitates were identified to be Ca10(PO4)6(OH)2(HA), the coating thickness and the n(Ca)/n(P) ratio increased continuously. The degree of crystallization of the coatings and the pH values of electrolyte decreased with the electrodeposition time increasing. The coatings were calcium-deficient apatite. In addition, the growth mechanism of coatings on C/C composites was also discussed.
2006, 35(7):1101-1104.
Abstract:
探讨了MnO2和Nb2O5掺杂对Pb（Mn1/3Sb2/3）0.05Zr0.47Ti0.48O3（PMSZT）材料相组成、显微结构、电性能及温度稳定性的影响.结果发现：合成温度900℃,可以得到钙钛矿结构;随着掺杂量的增大,四方相的含量减少,准同型相界向三方相移动;当MnO2过量0.1%,Nb2O5掺杂0.05%（均为质量分数）时,εT33/ε0,d33和Kp达到最佳值;随着MnO2和Nb2O5掺杂量增加,Qm值下降,谐振频率变化率随温度变化由正到负.
探讨了MnO2和Nb2O5掺杂对Pb（Mn1/3Sb2/3）0.05Zr0.47Ti0.48O3（PMSZT）材料相组成、显微结构、电性能及温度稳定性的影响.结果发现：合成温度900℃,可以得到钙钛矿结构;随着掺杂量的增大,四方相的含量减少,准同型相界向三方相移动;当MnO2过量0.1%,Nb2O5掺杂0.05%（均为质量分数）时,εT33/ε0,d33和Kp达到最佳值;随着MnO2和Nb2O5掺杂量增加,Qm值下降,谐振频率变化率随温度变化由正到负.
2006, 35(7):1105-1108.
Abstract:
在不同衬底温度下用脉冲激光沉积法（PLD）在n型硅（111）衬底上生长ZnO薄膜.通过对薄膜进行的X射线衍射（XRD）、傅里叶红外吸收（FTIR）、光致发光谱（PL）、透射电子显微镜（TEM）和选区电子衍射（SAED）的测量,研究了衬底温度对PLD方法制备的ZnO薄膜的结晶质量、发光性质以及微观结构的影响.发现在600℃的衬底温度下可以得到结晶质量最佳的ZnO薄膜.随着晶粒直径的减小,出现量子限制效应,在红外吸收和光致发光中的峰位均产生了蓝移.
在不同衬底温度下用脉冲激光沉积法（PLD）在n型硅（111）衬底上生长ZnO薄膜.通过对薄膜进行的X射线衍射（XRD）、傅里叶红外吸收（FTIR）、光致发光谱（PL）、透射电子显微镜（TEM）和选区电子衍射（SAED）的测量,研究了衬底温度对PLD方法制备的ZnO薄膜的结晶质量、发光性质以及微观结构的影响.发现在600℃的衬底温度下可以得到结晶质量最佳的ZnO薄膜.随着晶粒直径的减小,出现量子限制效应,在红外吸收和光致发光中的峰位均产生了蓝移.
2006, 35(7):1109-1112.
Abstract:
采用直流励磁磁控溅射法制备NdFeB稀土永磁薄膜.研究分析了衬底预热与定向沉积法对薄膜结构和磁性能的影响.实验结果表明：定向沉积技术制备出的NdFeB薄膜表面形成单一方向的柱状晶,该柱状晶生长方向垂直于薄膜表面,使薄膜具有良好的磁各向异性,薄膜矫顽力大大提高,H⊥/H∥比值改善.在预热温度200℃逐渐加热到500℃并保温10 min时,薄膜磁性能最佳.
采用直流励磁磁控溅射法制备NdFeB稀土永磁薄膜.研究分析了衬底预热与定向沉积法对薄膜结构和磁性能的影响.实验结果表明：定向沉积技术制备出的NdFeB薄膜表面形成单一方向的柱状晶,该柱状晶生长方向垂直于薄膜表面,使薄膜具有良好的磁各向异性,薄膜矫顽力大大提高,H⊥/H∥比值改善.在预热温度200℃逐渐加热到500℃并保温10 min时,薄膜磁性能最佳.
2006, 35(7):1113-1116.
Abstract:
利用回转振动粘度仪在液相线以上较大温度范围内,测量了In-55%Sb（质量分数）亚共晶合金熔体在不同的升降温过程中的粘度.实验结果表明,熔体经历的热历史对其粘度具有显著的影响.熔体在降温过程中的粘度高于升温过程中,在过热100℃后的降温过程中熔体的粘度较之无过热的降温过程中要低.在不同的热过程中,粘度发生转折变化的温度不同,在升温过程中,发生在850℃左右,在过热100℃和无过热的降温过程中,分别发生在750℃和650℃左右.熔体粘度的突变反映了熔体结构在相应温度的突然变化.
利用回转振动粘度仪在液相线以上较大温度范围内,测量了In-55%Sb（质量分数）亚共晶合金熔体在不同的升降温过程中的粘度.实验结果表明,熔体经历的热历史对其粘度具有显著的影响.熔体在降温过程中的粘度高于升温过程中,在过热100℃后的降温过程中熔体的粘度较之无过热的降温过程中要低.在不同的热过程中,粘度发生转折变化的温度不同,在升温过程中,发生在850℃左右,在过热100℃和无过热的降温过程中,分别发生在750℃和650℃左右.熔体粘度的突变反映了熔体结构在相应温度的突然变化.
25 Effects of Protective Coating Prepared by Atmospheric Plasma Spraying on Planar SOFC Interconnect
2006, 35(7):1117-1120.
Abstract:
在中温平板型固体氧化物燃料电池（ITSOFC）设计中,可以采用金属作为连接材料.Fe-16Cr合金是较为理想的金属连接材料,它存在的主要问题是连接体阴极侧表面的高温氧化和腐蚀,会导致电池性能的迅速降低.本研究采用空气等离子喷涂的方法喷涂了La0.8Sr0.2MnO3-σ（LSM）钙钛矿型保护涂层在金属连接板的表面,并讨论了主要过程参数及其作用效果.研究发现,喷涂后热处理是降低涂层孔隙率的有效方法,经喷涂-热处理后,涂层的孔隙率可降至1%以下.等离子喷涂LSM保护涂层后,Fe-16Cr合金的耐高温氧化性能明显提高,氧化速率降低了76%.
在中温平板型固体氧化物燃料电池（ITSOFC）设计中,可以采用金属作为连接材料.Fe-16Cr合金是较为理想的金属连接材料,它存在的主要问题是连接体阴极侧表面的高温氧化和腐蚀,会导致电池性能的迅速降低.本研究采用空气等离子喷涂的方法喷涂了La0.8Sr0.2MnO3-σ（LSM）钙钛矿型保护涂层在金属连接板的表面,并讨论了主要过程参数及其作用效果.研究发现,喷涂后热处理是降低涂层孔隙率的有效方法,经喷涂-热处理后,涂层的孔隙率可降至1%以下.等离子喷涂LSM保护涂层后,Fe-16Cr合金的耐高温氧化性能明显提高,氧化速率降低了76%.
2006, 35(7):1121-1125.
Abstract:
研究了热处理(T6强化处理及纯时效硬化处理)对渗流法生产的3种开孔泡沫铝合金在动态(~2.1×103s-1)和准静态(1.0×10-3s-1)下的压缩力学性能及能量吸收特性的影响。分别在MTS810材料试验机和分离式Hopkinson压杆(SHPB)上对3种泡沫铝合金材料进行了准静态及动态压缩实验。实验结果表明:与制备态相比,经时效硬化处理及T6强化处理的泡沫Al-Mg-Si合金和泡沫Al-Cu-Mg合金的动、静态压缩强度提高、平台区缩短,在一定应变下单位体积吸收的能量提高,而且均表现出对应变率的敏感性。而热处理对泡沫Al-Mg合金的动、静态压缩性能均没有影响,表明热处理对泡沫金属的作用与构成泡沫的基体金属关系密切,但与对应的实体金属的情况不同。须注意的是泡沫Al-Mg-Si合金和泡沫Al-Cu-Mg合金的纯时效硬化处理,也可以在一定程度上提高其压缩强度及吸能能力,与T6强化处理相比不需要固溶处理,不仅可以降低热处理成本,而且还避免了在水中淬火时对泡孔结构的破坏。实验结果还表明,泡沫Al-Cu-Mg合金的应变率敏感性受热处理路线的影响,而泡沫Al-Mg-Si合金的却不受影响。由于不同合金经相同热处理后会产生不同的沉淀硬化相甚至没有硬化相,因此,可以得出热处理对泡沫金属性能的影响主要取决于制备泡沫的基体金属。
研究了热处理(T6强化处理及纯时效硬化处理)对渗流法生产的3种开孔泡沫铝合金在动态(~2.1×103s-1)和准静态(1.0×10-3s-1)下的压缩力学性能及能量吸收特性的影响。分别在MTS810材料试验机和分离式Hopkinson压杆(SHPB)上对3种泡沫铝合金材料进行了准静态及动态压缩实验。实验结果表明:与制备态相比,经时效硬化处理及T6强化处理的泡沫Al-Mg-Si合金和泡沫Al-Cu-Mg合金的动、静态压缩强度提高、平台区缩短,在一定应变下单位体积吸收的能量提高,而且均表现出对应变率的敏感性。而热处理对泡沫Al-Mg合金的动、静态压缩性能均没有影响,表明热处理对泡沫金属的作用与构成泡沫的基体金属关系密切,但与对应的实体金属的情况不同。须注意的是泡沫Al-Mg-Si合金和泡沫Al-Cu-Mg合金的纯时效硬化处理,也可以在一定程度上提高其压缩强度及吸能能力,与T6强化处理相比不需要固溶处理,不仅可以降低热处理成本,而且还避免了在水中淬火时对泡孔结构的破坏。实验结果还表明,泡沫Al-Cu-Mg合金的应变率敏感性受热处理路线的影响,而泡沫Al-Mg-Si合金的却不受影响。由于不同合金经相同热处理后会产生不同的沉淀硬化相甚至没有硬化相,因此,可以得出热处理对泡沫金属性能的影响主要取决于制备泡沫的基体金属。
2006, 35(7):1126-1128.
Abstract:
In order to improve the quality of hollow Cu tubes, a horizontal continuous casting technology was developed in a pilot scale by using electromagnetic field of commercial frequency, and the effect of electromagnetic field on structure and mechanical properties were studied. The results show that the structure of hollow Cu tubes is refined substantially with the application of electromagnetic field and the average grain grand is increased from 3.1 to 8.3 and the uniformity along the circumference of the structure is improved obviously at the same time. The tensile strength is increased by 40% and the elongation is improved by 50% averagely if compared to those without electromagnetic field.
In order to improve the quality of hollow Cu tubes, a horizontal continuous casting technology was developed in a pilot scale by using electromagnetic field of commercial frequency, and the effect of electromagnetic field on structure and mechanical properties were studied. The results show that the structure of hollow Cu tubes is refined substantially with the application of electromagnetic field and the average grain grand is increased from 3.1 to 8.3 and the uniformity along the circumference of the structure is improved obviously at the same time. The tensile strength is increased by 40% and the elongation is improved by 50% averagely if compared to those without electromagnetic field.
2006, 35(7):1129-1131.
Abstract:
从铱盐和配体2,2,6,6-四甲基-3,5-庚二酮（thd）出发合成了一种新的β二酮前驱体Ir（thd）3,通过元素分析、红外光谱、核磁共振氢谱等手段对合成的前驱体进行了结构表征.热重分析表明,当温度升到290℃,前驱体基本挥发完全.使用合成的前驱体通过MOCVD沉积制备铱薄膜,利用XRD和AFM分析手段对薄膜的结构和表面形貌进行了表征.结果表明,所得到的薄膜的物相为铱晶相,无其它的杂质峰存在,薄膜表面连续、致密.
从铱盐和配体2,2,6,6-四甲基-3,5-庚二酮（thd）出发合成了一种新的β二酮前驱体Ir（thd）3,通过元素分析、红外光谱、核磁共振氢谱等手段对合成的前驱体进行了结构表征.热重分析表明,当温度升到290℃,前驱体基本挥发完全.使用合成的前驱体通过MOCVD沉积制备铱薄膜,利用XRD和AFM分析手段对薄膜的结构和表面形貌进行了表征.结果表明,所得到的薄膜的物相为铱晶相,无其它的杂质峰存在,薄膜表面连续、致密.
2006, 35(7):1132-1134.
Abstract:
Dynamic shear properties of the tungsten heavy alloys containing 90% to 97% W (mass) were investigated using a hat-shaped specimen on the Hopkinson rod of Split Compression at a shear strain rate of 105 s-1. The results show that the dynamic shear strength increased and the shear strain decreased with the tungsten content increasing. The shear strength increased linearly with the increase of volume fraction of tungsten particles in the alloys. The shear fracture surface mainly exhibits tungsten grains split and matrix phase rupture, and the split proportion of tungsten particles equaled approximately to the volume fraction of tungsten particles.
Dynamic shear properties of the tungsten heavy alloys containing 90% to 97% W (mass) were investigated using a hat-shaped specimen on the Hopkinson rod of Split Compression at a shear strain rate of 105 s-1. The results show that the dynamic shear strength increased and the shear strain decreased with the tungsten content increasing. The shear strength increased linearly with the increase of volume fraction of tungsten particles in the alloys. The shear fracture surface mainly exhibits tungsten grains split and matrix phase rupture, and the split proportion of tungsten particles equaled approximately to the volume fraction of tungsten particles.
2006, 35(7):1135-1138.
Abstract:
采用化学气相沉积方法,在1200℃～1600℃温度范围内,于不同的NH3流量条件下,合成了Si/C/N纳米粉体,研究了粉体的制备工艺、成分、相组成与其微波介电性能之间的关系.结果表明：NH3流量增加,粉体中N含量升高,随着合成温度的提高,粉体的晶化程度增强,主要为β-SiC相.在SiC晶格中固溶有N原子,且N原子的固溶量随合成温度升高而减少.Si/C/N纳米粉体中SiC微晶含量,以及SiC微晶中固溶的N原子浓度对粉体的ε＇,ε（＂）和损耗因子tgδ（ε＂/ε＇）起着重要作用.N原子固溶所导致的极化驰豫损耗和漏导损耗是Si/C/N纳米粉体具有吸波性能的主要机理.
采用化学气相沉积方法,在1200℃～1600℃温度范围内,于不同的NH3流量条件下,合成了Si/C/N纳米粉体,研究了粉体的制备工艺、成分、相组成与其微波介电性能之间的关系.结果表明：NH3流量增加,粉体中N含量升高,随着合成温度的提高,粉体的晶化程度增强,主要为β-SiC相.在SiC晶格中固溶有N原子,且N原子的固溶量随合成温度升高而减少.Si/C/N纳米粉体中SiC微晶含量,以及SiC微晶中固溶的N原子浓度对粉体的ε＇,ε（＂）和损耗因子tgδ（ε＂/ε＇）起着重要作用.N原子固溶所导致的极化驰豫损耗和漏导损耗是Si/C/N纳米粉体具有吸波性能的主要机理.
2006, 35(7):1139-1142.
Abstract:
采用液相共沉淀方法,以ZnSO4·7H2O为原料,GaCl3为掺杂化合物,NH4HCO3为沉淀剂合成碱式碳酸锌前驱体,通过在H2气氛下煅烧,制得Ga3+均匀掺杂的纳米氧化锌导电粉体.利用SEM,TEM,XRD,XPS和BET等分析手段对粉体的性能进行表征.结果表明,这种方法合成的导电氧化锌粉体材料颗粒尺寸较小、粒度分布均匀(约在20 nm～40 nm的范围内),颗粒呈类球状形貌,具有较好的分散性能.研究了Ga3+掺杂对氧化锌粉体导电性能的影响.结果表明,在Ga3+掺杂量为2.2mol%时,制得的氧化锌粉体的导电性能最好,体积电阻率达到2.0Ω·cm.
采用液相共沉淀方法,以ZnSO4·7H2O为原料,GaCl3为掺杂化合物,NH4HCO3为沉淀剂合成碱式碳酸锌前驱体,通过在H2气氛下煅烧,制得Ga3+均匀掺杂的纳米氧化锌导电粉体.利用SEM,TEM,XRD,XPS和BET等分析手段对粉体的性能进行表征.结果表明,这种方法合成的导电氧化锌粉体材料颗粒尺寸较小、粒度分布均匀(约在20 nm～40 nm的范围内),颗粒呈类球状形貌,具有较好的分散性能.研究了Ga3+掺杂对氧化锌粉体导电性能的影响.结果表明,在Ga3+掺杂量为2.2mol%时,制得的氧化锌粉体的导电性能最好,体积电阻率达到2.0Ω·cm.
2006, 35(7):1143-1145.
Abstract:
This paper investigates the intermetallic compound on the interface between AuSn solder and Au or Au/Ni metallization layer after laser soldering by SEM and EDX analysis. The effects of laser power and heating time on the evolution of intermetallic compounds on the interface are discussed. The results show that the components of Jntermetallic compound depart from the eutectic arrest due to Au dissolving quickly into the solder near the interface and forming a stable AusSn at the interface on the condition of laser heating and cooling quickly. With the increase of laser power and heating time, the undissolved Au layer becomes thinner and the AusSn grows into the solder.
This paper investigates the intermetallic compound on the interface between AuSn solder and Au or Au/Ni metallization layer after laser soldering by SEM and EDX analysis. The effects of laser power and heating time on the evolution of intermetallic compounds on the interface are discussed. The results show that the components of Jntermetallic compound depart from the eutectic arrest due to Au dissolving quickly into the solder near the interface and forming a stable AusSn at the interface on the condition of laser heating and cooling quickly. With the increase of laser power and heating time, the undissolved Au layer becomes thinner and the AusSn grows into the solder.
2006, 35(7):1146-1149.
Abstract:
Silver nanoparticles were prepared by the reduction reaction of silver nitrate solution with sodium hypophosphite in polyvinylpyrrolidone solution. The silver sol was coagulated by adding ammonia solution. Some technical conditions, such as pH value, ammonia concentration, ammonia dropping velocity and stirring rate were tested in order to get silver nanoparticles by filtrating silver sols. The results showed that the separation of solid silver nanoparticles with liquid solution was improved and the silver nanoparticles with different sizes were prepared using this method. The silver powders with particle size of 10 nm~20 nm were successfully separated from the silver sol by adding mixed solution of flocculent and organic alkaline agents. This process is simple and ordinary, needs some simply apparatuses only and consumed less energy with a high silver production capacity. Therefore, it is feasible for industrialized preparation of silver nanoparticles. The products were analyzed by transmission electron microscope (TEM) and X-ray diffraction (XRD) and shown that the particles were pure metal silver with high dispersible spherical form and diameters from 10 nm to 40 nm.
Silver nanoparticles were prepared by the reduction reaction of silver nitrate solution with sodium hypophosphite in polyvinylpyrrolidone solution. The silver sol was coagulated by adding ammonia solution. Some technical conditions, such as pH value, ammonia concentration, ammonia dropping velocity and stirring rate were tested in order to get silver nanoparticles by filtrating silver sols. The results showed that the separation of solid silver nanoparticles with liquid solution was improved and the silver nanoparticles with different sizes were prepared using this method. The silver powders with particle size of 10 nm~20 nm were successfully separated from the silver sol by adding mixed solution of flocculent and organic alkaline agents. This process is simple and ordinary, needs some simply apparatuses only and consumed less energy with a high silver production capacity. Therefore, it is feasible for industrialized preparation of silver nanoparticles. The products were analyzed by transmission electron microscope (TEM) and X-ray diffraction (XRD) and shown that the particles were pure metal silver with high dispersible spherical form and diameters from 10 nm to 40 nm.
2006, 35(7):1150-1153.
Abstract:
A qualitative study on the effects of humidity on activity of aluminum nanoparticles has been reported in this letter. The Al nanoparticles were synthesized by the process of hybrid induction and laser heating (HILH). In order to understand the stability of the oxide coating from aluminum nanoparticles, the Al nanoparticles were examined using high-resolution transmission electron microscopy (HRTEM) and the thermal behaviors were identified by DSC-TG. It was found that a compact amorphous oxide layer of 3 nm in thickness covered the original Al nanoparticles. After stored for 8 weeks, the oxide layer grew up to 5 nm in thickness, and the oxidation diffused to the interior of Al nanoparticles. The results indicate that the activity of Al nanoparticles is deeply influenced by the environment, especial the humidity. A higher relative humidity would accelerate the aging of Al nanoparticles. The DSC-TG results show that the oxidation of Al nanoparticles occurs at least in two steps.
A qualitative study on the effects of humidity on activity of aluminum nanoparticles has been reported in this letter. The Al nanoparticles were synthesized by the process of hybrid induction and laser heating (HILH). In order to understand the stability of the oxide coating from aluminum nanoparticles, the Al nanoparticles were examined using high-resolution transmission electron microscopy (HRTEM) and the thermal behaviors were identified by DSC-TG. It was found that a compact amorphous oxide layer of 3 nm in thickness covered the original Al nanoparticles. After stored for 8 weeks, the oxide layer grew up to 5 nm in thickness, and the oxidation diffused to the interior of Al nanoparticles. The results indicate that the activity of Al nanoparticles is deeply influenced by the environment, especial the humidity. A higher relative humidity would accelerate the aging of Al nanoparticles. The DSC-TG results show that the oxidation of Al nanoparticles occurs at least in two steps.
2006, 35(7):1154-1157.
Abstract:
用真空吹铸法制备了直径为2 mm的Mg65Cu25Y10-xTbx（x=0,2,4,6,8,10）块体非晶合金棒,采用X射线衍射分析（XRD）、差热分析（DTA）分别对非晶合金的结构和形成能力进行了研究.结果表明：Mg65Cu25Y10-xTbx合金均能形成非晶合金;随着合金元素Tb含量的增加其玻璃形成能力逐渐增强,当x=8时,合金的玻璃形成能力最强,随后当x=10时,有所下降.通过对Mg65Cu25Y10-xTbx合金系的电负性差与原子尺寸参数的计算,合理地解释了产生这一现象的原因可能是由于Mg65Cu25Y10-xTbx合金的电负性差的变化所引起的;当x=6,8时,合金的玻璃形成能力较强,DTA图显示其成分可能属于共晶点成分,同时通过计算得出此两种非晶合金的λ值与由原子团族模型推导出的λ=0.18相差较大.
用真空吹铸法制备了直径为2 mm的Mg65Cu25Y10-xTbx（x=0,2,4,6,8,10）块体非晶合金棒,采用X射线衍射分析（XRD）、差热分析（DTA）分别对非晶合金的结构和形成能力进行了研究.结果表明：Mg65Cu25Y10-xTbx合金均能形成非晶合金;随着合金元素Tb含量的增加其玻璃形成能力逐渐增强,当x=8时,合金的玻璃形成能力最强,随后当x=10时,有所下降.通过对Mg65Cu25Y10-xTbx合金系的电负性差与原子尺寸参数的计算,合理地解释了产生这一现象的原因可能是由于Mg65Cu25Y10-xTbx合金的电负性差的变化所引起的;当x=6,8时,合金的玻璃形成能力较强,DTA图显示其成分可能属于共晶点成分,同时通过计算得出此两种非晶合金的λ值与由原子团族模型推导出的λ=0.18相差较大.
2006, 35(7):1158-1161.
Abstract:
采用浸渍法制备负载金属Pd(其中金属Pd含量0.6g/L)活性组分的金属蜂窝载体催化剂,应用于甲烷部分氧化制合成气。实验表明,焙烧温度为950℃的催化剂较600℃的催化剂甲烷转化率、CO和H2的选择性更高,焙烧温度为950℃的催化剂在反应温度800℃,GHSV=1×105ml/g·h条件下,甲烷转化率为91%,CO和H2的选择性分别达到90%和89%。用SEM与XPS对催化剂进行表征,结果表明,950℃焙烧催化剂并没有出现明显的烧结现象,且可能由于更多零价Pd的出现,使得该催化剂的性能更好。由于金属蜂窝载体优良的导热性,对950℃焙烧温度制备的金属蜂窝催化剂,催化剂床层的飞温点温度小于880℃,可以解决其它类型催化剂在甲烷部分氧化反应中出现的飞温问题,具有一定的工业化意义。
采用浸渍法制备负载金属Pd(其中金属Pd含量0.6g/L)活性组分的金属蜂窝载体催化剂,应用于甲烷部分氧化制合成气。实验表明,焙烧温度为950℃的催化剂较600℃的催化剂甲烷转化率、CO和H2的选择性更高,焙烧温度为950℃的催化剂在反应温度800℃,GHSV=1×105ml/g·h条件下,甲烷转化率为91%,CO和H2的选择性分别达到90%和89%。用SEM与XPS对催化剂进行表征,结果表明,950℃焙烧催化剂并没有出现明显的烧结现象,且可能由于更多零价Pd的出现,使得该催化剂的性能更好。由于金属蜂窝载体优良的导热性,对950℃焙烧温度制备的金属蜂窝催化剂,催化剂床层的飞温点温度小于880℃,可以解决其它类型催化剂在甲烷部分氧化反应中出现的飞温问题,具有一定的工业化意义。
2006, 35(7):1162-1166.
Abstract:
The progresses in the ductility and toughness improvements for the structural materials of intermetallic compounds, especially the NiAl-based alloys, are reviewed in this paper. Owing to their intrinsic brittleness, the forming capability of these materials is poor. On the other hand, the advances in the fabrication process are also included in this paper since the materials properties are closely related to it.
The progresses in the ductility and toughness improvements for the structural materials of intermetallic compounds, especially the NiAl-based alloys, are reviewed in this paper. Owing to their intrinsic brittleness, the forming capability of these materials is poor. On the other hand, the advances in the fabrication process are also included in this paper since the materials properties are closely related to it.
2006, 35(7):1167-1171.
Abstract:
Electrospinning technique is playing an important role and has been regarded as one of the simplest and most effective techniques in the field of nanofibers fabrication. Various kinds of nanofibers have been prepared using this method, including polymers and inorganic nanofibers. In this paper, a comprehensive review is presented on the fabrication of inorganic nanofibers using electrospinning technique, including its mechanism, modification and effecting factors. In addition, the applications and future trends are presented and discussed for the inorganic nanofibers in this paper.
Electrospinning technique is playing an important role and has been regarded as one of the simplest and most effective techniques in the field of nanofibers fabrication. Various kinds of nanofibers have been prepared using this method, including polymers and inorganic nanofibers. In this paper, a comprehensive review is presented on the fabrication of inorganic nanofibers using electrospinning technique, including its mechanism, modification and effecting factors. In addition, the applications and future trends are presented and discussed for the inorganic nanofibers in this paper.
2006, 35(7):1172-1176.
Abstract:
The fatigue fracture resistance of FSW joints is one of the very important properties to assess the capability of FSW structure in practical application. The recent advances on the fatigue properties of FSW joints were summarized in details, which mainly included the test results of S-N curves, the relationship between fatigue crack growth rate da/dN and AK, the threshold value of stress intensity factor AKth and the fatigue crack growth behavior in corrosion environment. The influences of various factors on the fatigue behavior of FSW joints were analyzed and the existed problems for the fatigue assessment of FSW were proposed and discussed.
The fatigue fracture resistance of FSW joints is one of the very important properties to assess the capability of FSW structure in practical application. The recent advances on the fatigue properties of FSW joints were summarized in details, which mainly included the test results of S-N curves, the relationship between fatigue crack growth rate da/dN and AK, the threshold value of stress intensity factor AKth and the fatigue crack growth behavior in corrosion environment. The influences of various factors on the fatigue behavior of FSW joints were analyzed and the existed problems for the fatigue assessment of FSW were proposed and discussed.
