Volume 36,Issue 3,2007 Table of Contents
2007, 36(3):377-380.
Abstract:
研究了Al-1％Si合金水平连铸过程中施加功率超声对铸坯凝固组织的影响，并对其机理进行了探讨。实验结果表明，随着超声波功率的提高，铸坯凝固组织得到了细化，同时Si元素晶界偏析得到了抑制。理论分析认为当功率超声频率为22．3kHz时，能够发生空化效应的最大空化泡半径为1．02×10^-4m，且随着超声功率的增加，空化泡数量增多。空化泡崩溃时产生局部高温高压，从而导致晶粒细化，改善了Si元素的分布情况。
研究了Al-1％Si合金水平连铸过程中施加功率超声对铸坯凝固组织的影响，并对其机理进行了探讨。实验结果表明，随着超声波功率的提高，铸坯凝固组织得到了细化，同时Si元素晶界偏析得到了抑制。理论分析认为当功率超声频率为22．3kHz时，能够发生空化效应的最大空化泡半径为1．02×10^-4m，且随着超声功率的增加，空化泡数量增多。空化泡崩溃时产生局部高温高压，从而导致晶粒细化，改善了Si元素的分布情况。
2007, 36(3):381-385.
Abstract:
讨论了Mn对镁基准晶中间合金中三维二十面体球形准晶相形成过程的影响。研究表明：当在Mg-Zn-Y基准晶中间合金熔体中加入一定量的Mn元素后，在常规铸造条件下的结晶凝固过程中，完全可以改变Mg-Zn-Y基准晶中间合金中准晶的形成过程，获得稳定的均一二十面体初生Mg45Zn47Y5Mn3准晶相，避免了十面体准晶相的出现，改变了准晶相最终的形貌，由于Mn的加入，使初生准晶相的颗粒尺寸明显变小，使之由尺寸为60gm～80gm的花瓣状变成尺寸为≤20gm的球形状。Mn的加入，降低了镁基准晶中间合金的生产成本，为工业化生产提供了便利条件。
讨论了Mn对镁基准晶中间合金中三维二十面体球形准晶相形成过程的影响。研究表明：当在Mg-Zn-Y基准晶中间合金熔体中加入一定量的Mn元素后，在常规铸造条件下的结晶凝固过程中，完全可以改变Mg-Zn-Y基准晶中间合金中准晶的形成过程，获得稳定的均一二十面体初生Mg45Zn47Y5Mn3准晶相，避免了十面体准晶相的出现，改变了准晶相最终的形貌，由于Mn的加入，使初生准晶相的颗粒尺寸明显变小，使之由尺寸为60gm～80gm的花瓣状变成尺寸为≤20gm的球形状。Mn的加入，降低了镁基准晶中间合金的生产成本，为工业化生产提供了便利条件。
2007, 36(3):386-389.
Abstract:
用高温固相法在900℃，保温6h的条件下制备了YVO4单相粉末样品。在紫外光254nm激发下，YVO4：Eu^3＋的激发光谱由VO4^3＋的吸收带和Eu^3＋的电荷迁移带组成。发射光谱为Eu^3＋的^5D0→^7Fj（J=1,2，4）跃迁。在Eu^3＋含量一定的情况下掺杂Bi^3＋和sc^3＋，随着Bi^3＋浓度的增加，激发光谱宽化，但发射强度变弱；SC^3＋浓度的增加则使YVo4：Eu^3＋的发射强度先增加后降低。在147nm激发下，（Y,Bi，Sc）VO4：Eu^3＋的发射光谱相对于YVO4：Eu^3＋有降低趋势。
用高温固相法在900℃，保温6h的条件下制备了YVO4单相粉末样品。在紫外光254nm激发下，YVO4：Eu^3＋的激发光谱由VO4^3＋的吸收带和Eu^3＋的电荷迁移带组成。发射光谱为Eu^3＋的^5D0→^7Fj（J=1,2，4）跃迁。在Eu^3＋含量一定的情况下掺杂Bi^3＋和sc^3＋，随着Bi^3＋浓度的增加，激发光谱宽化，但发射强度变弱；SC^3＋浓度的增加则使YVo4：Eu^3＋的发射强度先增加后降低。在147nm激发下，（Y,Bi，Sc）VO4：Eu^3＋的发射光谱相对于YVO4：Eu^3＋有降低趋势。
Wang Zewen
,
Jie Wanqi
,
Li Peisen
,
Gu Zhi
,
Liu Changyou
,
Li Qiang
,
Zha Gangqiang
,
Wang Xiaoqin
2007, 36(3):390-393.
Abstract:
Electronic properties of several Hg1-xMnxTe wafers before and after chemical polish were characterized by Van Der Pauw method at 77 K. Results showed that values of resistivity and Hall coefficient of the wafers before etching are lower than those after etching, while Hall mobility and carrier density were higher. The maximum of resistivity decreased by 25%, the maximum of Hall mobility increased by 31%, but Hall coefficient and carrier density changed only by about 2% before and after etching. There existed a lot of dislocations in surface damaged layer, resulting in the decrease of Hall mobility of charge carrier, but the values of Hall mobility of wafers before chemical polish were higher, the minimum of which increased by 21%. It is a abnormal phenomena. All the experimental results can be explained using a three-layer model.
Electronic properties of several Hg1-xMnxTe wafers before and after chemical polish were characterized by Van Der Pauw method at 77 K. Results showed that values of resistivity and Hall coefficient of the wafers before etching are lower than those after etching, while Hall mobility and carrier density were higher. The maximum of resistivity decreased by 25%, the maximum of Hall mobility increased by 31%, but Hall coefficient and carrier density changed only by about 2% before and after etching. There existed a lot of dislocations in surface damaged layer, resulting in the decrease of Hall mobility of charge carrier, but the values of Hall mobility of wafers before chemical polish were higher, the minimum of which increased by 21%. It is a abnormal phenomena. All the experimental results can be explained using a three-layer model.
2007, 36(3):394-397.
Abstract:
以Pt，Pd，Rh3种贵金属作为汽油车用三效催化剂的主要催化活性组分，制备了2组具有不同组合与分布形式的分层催化剂和分区催化剂，并通过发动机台架测试系统进行了催化活性评价。通过对表征催化剂催化性能的空燃比特性、起燃特性和催化转化效率的对比分析，研究了3种贵金属的组合与分布对催化剂3大特性的影响。结果表明：贵金属的组合与分布方式会对催化剂的3大特性产生显著影响；贵金属分层分布催化剂与分区催化剂相比具有更高的空燃比特性和起燃特性，其中PtRh（o）／Pd（i）催化剂表现最佳，但贵金属分区催化剂，主要是PtRh组合在近发动机端的分区催化剂，在所有催化剂中表现出最优异的起燃特性；因此，在进行欧3、欧4等车用排放控制系统设计时，可以利用不同贵金属组合与分布催化剂的独特性能优势，在同一载体或同一系统中的不同载体上进行可控的贵金属负载与分布，来提高催化剂的综合性能；以这种方式获得的效果预期比单纯提高贵金属含量获得的效果好得多。
以Pt，Pd，Rh3种贵金属作为汽油车用三效催化剂的主要催化活性组分，制备了2组具有不同组合与分布形式的分层催化剂和分区催化剂，并通过发动机台架测试系统进行了催化活性评价。通过对表征催化剂催化性能的空燃比特性、起燃特性和催化转化效率的对比分析，研究了3种贵金属的组合与分布对催化剂3大特性的影响。结果表明：贵金属的组合与分布方式会对催化剂的3大特性产生显著影响；贵金属分层分布催化剂与分区催化剂相比具有更高的空燃比特性和起燃特性，其中PtRh（o）／Pd（i）催化剂表现最佳，但贵金属分区催化剂，主要是PtRh组合在近发动机端的分区催化剂，在所有催化剂中表现出最优异的起燃特性；因此，在进行欧3、欧4等车用排放控制系统设计时，可以利用不同贵金属组合与分布催化剂的独特性能优势，在同一载体或同一系统中的不同载体上进行可控的贵金属负载与分布，来提高催化剂的综合性能；以这种方式获得的效果预期比单纯提高贵金属含量获得的效果好得多。
2007, 36(3):398-401.
Abstract:
The influence of Suction cast on phase structures and hydrogen storage properties of TiVCr based alloys has been investigated in this work. It is showed that suction cast is beneficial to the formation of a single solid solution phase with BCC structure resulting in the slight decrease of the lattice parameters. The slope coefficient Sf and the desorbing plateau pressure of the alloys were decreased and the capacity of absorption and desorption was increased by suction cast. Also, the activation performances of the alloys were reduced by suction cast. The desorbing plateau pressure and the capacity of desorption of the alloys increased with increasing Cr content.
The influence of Suction cast on phase structures and hydrogen storage properties of TiVCr based alloys has been investigated in this work. It is showed that suction cast is beneficial to the formation of a single solid solution phase with BCC structure resulting in the slight decrease of the lattice parameters. The slope coefficient Sf and the desorbing plateau pressure of the alloys were decreased and the capacity of absorption and desorption was increased by suction cast. Also, the activation performances of the alloys were reduced by suction cast. The desorbing plateau pressure and the capacity of desorption of the alloys increased with increasing Cr content.
2007, 36(3):402-404.
Abstract:
为开发免训练、高可恢复变形量的FeMnSiCrNi合金，研究了直接时效和形变时效对FeMnsiCrNiNbC合金形状记忆效应的影响，通过TEM分析了微观组织的变化。结果表明：与直接时效相比，10％室温形变后时效对合金形状记忆效应的提高更显著。形变后产生的晶体缺陷提供了NbC的形核位置，使NbC的析出速度显著增加，析出数量增多，粒径减小，因而对基体的强化效果更显著。同时NbC析出导致的弹性应变场提高了应力诱发￡马氏体逆转变的可逆性。
为开发免训练、高可恢复变形量的FeMnSiCrNi合金，研究了直接时效和形变时效对FeMnsiCrNiNbC合金形状记忆效应的影响，通过TEM分析了微观组织的变化。结果表明：与直接时效相比，10％室温形变后时效对合金形状记忆效应的提高更显著。形变后产生的晶体缺陷提供了NbC的形核位置，使NbC的析出速度显著增加，析出数量增多，粒径减小，因而对基体的强化效果更显著。同时NbC析出导致的弹性应变场提高了应力诱发￡马氏体逆转变的可逆性。
2007, 36(3):405-407.
Abstract:
On the basis of ascertaining that phosphomolybdic acid modified platinum electrode has higher catalytic activity to methanol oxidation, three kinds of transition metal substituted phosphomolybdic acids were synthesized, and the IR spectrum indicated that the compounds still kept Keggin structure. The transition metal substituted phosphomolybdic acid modified platinum electrodes were prepared, and the electrochemical behaviors of the transition metal substituted phosphomolybdic acid modified platinum electrodes and their electrocatalytic effects to methanol oxidation were studied. Meanwhile, the results showed that the three kinds of heteropolyacid modified platinum electrodes had higher electrocatalytic activity to methanol oxidation, manganese substituted phosphomolybdic acid modified platinum electrode had the highest electrocatalytic activity among them.
On the basis of ascertaining that phosphomolybdic acid modified platinum electrode has higher catalytic activity to methanol oxidation, three kinds of transition metal substituted phosphomolybdic acids were synthesized, and the IR spectrum indicated that the compounds still kept Keggin structure. The transition metal substituted phosphomolybdic acid modified platinum electrodes were prepared, and the electrochemical behaviors of the transition metal substituted phosphomolybdic acid modified platinum electrodes and their electrocatalytic effects to methanol oxidation were studied. Meanwhile, the results showed that the three kinds of heteropolyacid modified platinum electrodes had higher electrocatalytic activity to methanol oxidation, manganese substituted phosphomolybdic acid modified platinum electrode had the highest electrocatalytic activity among them.
2007, 36(3):408-411.
Abstract:
采用热液静挤压工艺对液相烧结态93W-4．9Ni-2．1Fe合金进行了变形，挤压温度为1200℃，变形量60％～75％：系统研究了挤压态合金力学性能与显微组织之间的关系。结果表明，挤压态合金的钨颗粒内部表征为高密度位错构成的胞状亚结构，而粘结相在挤压过程中发生了动态再结晶。挤压态合金的强度随着变形量的增大而不断增加，延伸率则随着变形量的增大而不断减小。
采用热液静挤压工艺对液相烧结态93W-4．9Ni-2．1Fe合金进行了变形，挤压温度为1200℃，变形量60％～75％：系统研究了挤压态合金力学性能与显微组织之间的关系。结果表明，挤压态合金的钨颗粒内部表征为高密度位错构成的胞状亚结构，而粘结相在挤压过程中发生了动态再结晶。挤压态合金的强度随着变形量的增大而不断增加，延伸率则随着变形量的增大而不断减小。
2007, 36(3):412-415.
Abstract:
HfO2 thin films were prepared by electron beam evaporation.The residual stress was measured by viewing the substrate deflection using ZYGO interferometer. The microstructure of the HfO2 thin films was inspected by X-ray diffraction (XRD). The results show that the stress is tensile and the value of the residual stress decreases with the increase of the thin film thickness, and residual stress becomes stable when the film thickness reaches a certain value. The interplanar distance of the thin film increases with the increase of the thin film thickness, which is corresponding to the variation of the residual stress. The evolution of the residual stress may be due to the variation of the microstructure as the increasing of the thin film thickness.
HfO2 thin films were prepared by electron beam evaporation.The residual stress was measured by viewing the substrate deflection using ZYGO interferometer. The microstructure of the HfO2 thin films was inspected by X-ray diffraction (XRD). The results show that the stress is tensile and the value of the residual stress decreases with the increase of the thin film thickness, and residual stress becomes stable when the film thickness reaches a certain value. The interplanar distance of the thin film increases with the increase of the thin film thickness, which is corresponding to the variation of the residual stress. The evolution of the residual stress may be due to the variation of the microstructure as the increasing of the thin film thickness.
2007, 36(3):416-419.
Abstract:
GaN epitaxy films were grown on (0001) oriented sapphire substrate by metal-organic vapor deposition(MOCVD). AFM and SEM were used to analyze the surface morphology of GaN films. Hardness and critical load of GaN films were measured by an nano-indentation tester, friction coefficient by reciprocating UMT-2MT tribometer. It is found that the surface of GaN film is smooth and the epitaxial growth mechanism is in two-dimension mode, GaN epitaxy films also belong to ultra-hardness materials, whose hardness is 22.1 MPa and elastic modulus is 299.5 GPa. Adhesion strength of epitaxial GaN to sapphire is high, and critical load reaches 1.6 N. Friction coefficient against GCr15 ball is steadily close to 0.13, while GaN films turns to be broken rapidly by using Si3N4 ceramic ball as counterpart.
GaN epitaxy films were grown on (0001) oriented sapphire substrate by metal-organic vapor deposition(MOCVD). AFM and SEM were used to analyze the surface morphology of GaN films. Hardness and critical load of GaN films were measured by an nano-indentation tester, friction coefficient by reciprocating UMT-2MT tribometer. It is found that the surface of GaN film is smooth and the epitaxial growth mechanism is in two-dimension mode, GaN epitaxy films also belong to ultra-hardness materials, whose hardness is 22.1 MPa and elastic modulus is 299.5 GPa. Adhesion strength of epitaxial GaN to sapphire is high, and critical load reaches 1.6 N. Friction coefficient against GCr15 ball is steadily close to 0.13, while GaN films turns to be broken rapidly by using Si3N4 ceramic ball as counterpart.
2007, 36(3):420-423.
Abstract:
The microstructure of the laser cladding coating with pre-placed B4C and B4C+Ti powders on TC4 substrate was analyzed using XRD, SEM and EDS. The results showed that both the coatings consisted of TiB2, TiB, TiC1-x and Ti phases. Some of Ti in the substrate was melted and mixed into the laser melting pool and reacted with B4C in-situ producing TiB, TiB2 and TiC1-x. The in-situ produced TiC1-x shows morphology of dendrite. The in-situ produced TiB2 shows morphology of whisker with larger size. The in-situ produced TiB shows morphology of whisker with smaller size. The bonding between the coating and TC4 alloy substrate was perfect. No crack and void were found at the interface. The heat-affected zone in the Ti substrate exhibited typical martensite morphology of quenched microstructure. Compared with B4C cladding coating, the B4C+10wt%Ti cladding coating had a finer microstructure and higher content of TiB phase and lower content of the TiB2 phase.
The microstructure of the laser cladding coating with pre-placed B4C and B4C+Ti powders on TC4 substrate was analyzed using XRD, SEM and EDS. The results showed that both the coatings consisted of TiB2, TiB, TiC1-x and Ti phases. Some of Ti in the substrate was melted and mixed into the laser melting pool and reacted with B4C in-situ producing TiB, TiB2 and TiC1-x. The in-situ produced TiC1-x shows morphology of dendrite. The in-situ produced TiB2 shows morphology of whisker with larger size. The in-situ produced TiB shows morphology of whisker with smaller size. The bonding between the coating and TC4 alloy substrate was perfect. No crack and void were found at the interface. The heat-affected zone in the Ti substrate exhibited typical martensite morphology of quenched microstructure. Compared with B4C cladding coating, the B4C+10wt%Ti cladding coating had a finer microstructure and higher content of TiB phase and lower content of the TiB2 phase.
2007, 36(3):424-427.
Abstract:
采用热分解法制备了以钛为基体、SnO2＋Sb2O3为中间层、RuO2＋PbO2为活性层的Ti／SnO2＋Sb2O3／RuO2＋PbO2电极。应用极化曲线法和循环伏安法测定不同RuO2含量下电极在25℃，0．5mol／LH2SO4溶液中的电催化活性。实验结果表明，随着RuO2含量的增加，相同电极电位下的电流密度增大；相同的扫描速率下，RuO2含量增加，电极的伏安电荷值增加，即电极的电催化活性随着RuO2含量的增加而增加。在1．0mol／LH2SO4溶液中，60℃、电流密度为2．0A／cm^2条件下，电极寿命快速检测结果表明，Ti／SnO2＋Sb2O3／RuO2＋PbO2电极的寿命随RuO2含量的增加而下降；但与不加有SnO2＋Sb2O3中间层的Ti／RuO2＋PbO2电极相比，电极寿命则显著增加。RuO2的含量还对电极的表面形貌有明显的影响。
采用热分解法制备了以钛为基体、SnO2＋Sb2O3为中间层、RuO2＋PbO2为活性层的Ti／SnO2＋Sb2O3／RuO2＋PbO2电极。应用极化曲线法和循环伏安法测定不同RuO2含量下电极在25℃，0．5mol／LH2SO4溶液中的电催化活性。实验结果表明，随着RuO2含量的增加，相同电极电位下的电流密度增大；相同的扫描速率下，RuO2含量增加，电极的伏安电荷值增加，即电极的电催化活性随着RuO2含量的增加而增加。在1．0mol／LH2SO4溶液中，60℃、电流密度为2．0A／cm^2条件下，电极寿命快速检测结果表明，Ti／SnO2＋Sb2O3／RuO2＋PbO2电极的寿命随RuO2含量的增加而下降；但与不加有SnO2＋Sb2O3中间层的Ti／RuO2＋PbO2电极相比，电极寿命则显著增加。RuO2的含量还对电极的表面形貌有明显的影响。
2007, 36(3):428-430.
Abstract:
In order to develop the AB5-type hydrogen storage alloys with multi-component alloying elements, the alloys MlNi3.55Co0.3Mn0.4Al0.25Cu0.15Fe0.1Cr0.1Zn0.13Vx(x=0.02, 0.05, 0.08) were prepared, and their discharge capacity, cycle stability were tested and analyzed. The results show that the low-Co content hydrogen storage alloys with additive V has good electrochemical properties. It is found that the electrochemical properties of low-Co content hydrogen storage alloys with x=0.02 are better than those of the other alloys. The effect of V on the electrochemical properties is related to the change of the microstructures of the alloys.
In order to develop the AB5-type hydrogen storage alloys with multi-component alloying elements, the alloys MlNi3.55Co0.3Mn0.4Al0.25Cu0.15Fe0.1Cr0.1Zn0.13Vx(x=0.02, 0.05, 0.08) were prepared, and their discharge capacity, cycle stability were tested and analyzed. The results show that the low-Co content hydrogen storage alloys with additive V has good electrochemical properties. It is found that the electrochemical properties of low-Co content hydrogen storage alloys with x=0.02 are better than those of the other alloys. The effect of V on the electrochemical properties is related to the change of the microstructures of the alloys.
2007, 36(3):431-434.
Abstract:
The influence of gold nanoparticles on the optical properties of dye molecules of Rhodamine 6G (R6G) and fluorescein (FL) has been studied. The adsorption of positively charged R6G on the surface of gold nanoparticles passivated with citrate resulted in a red-shift of the surface plasmon resonance (SPR) of the gold nanoparticles. Negatively charged FL, on the other hand, had slight influence on the SPR of the gold nanoparticles, likely due to the electrostatic repulsion between FL and citrates. The surface-enhanced Raman spectrum of R6G on the gold nanoparticles demonstrated that R6G adapted a parallel orientation relative to the surface of the gold nanoparticles. The nonradiative energy decay and unfavorable orientation of R6G to gold nanoparticles led to a decrease in the intensity of the emission of R6G. In contrary, the emission intensity of FL was substantially increased in the presence of the gold nanoparticles, due to the necessary space generated by the electrostatic repulsion between FL molecules and the citrate-passivated gold nanoparticles.
The influence of gold nanoparticles on the optical properties of dye molecules of Rhodamine 6G (R6G) and fluorescein (FL) has been studied. The adsorption of positively charged R6G on the surface of gold nanoparticles passivated with citrate resulted in a red-shift of the surface plasmon resonance (SPR) of the gold nanoparticles. Negatively charged FL, on the other hand, had slight influence on the SPR of the gold nanoparticles, likely due to the electrostatic repulsion between FL and citrates. The surface-enhanced Raman spectrum of R6G on the gold nanoparticles demonstrated that R6G adapted a parallel orientation relative to the surface of the gold nanoparticles. The nonradiative energy decay and unfavorable orientation of R6G to gold nanoparticles led to a decrease in the intensity of the emission of R6G. In contrary, the emission intensity of FL was substantially increased in the presence of the gold nanoparticles, due to the necessary space generated by the electrostatic repulsion between FL molecules and the citrate-passivated gold nanoparticles.
2007, 36(3):435-439.
Abstract:
The phase transition of Copper-tungsten films deposited on Si (100) and Al2O3 substrates took place by means of in situ annealing in vacuum chamber at different temperatures. X-ray diffraction (XRD) and the polarization phase shift technique were employed to characterize the microstructure and residual stress of Cu-W films, respectively. The results indicated that the two successive but distinctive stages of phase transition appeared with the change of annealing temperatures, i.e., W (Cu) solution formation and two-phase crystalline (W and Cu) structure formation. The relationship between phase transition and residual stress was investigated, the tensile stress was caused during phase transition, whereas it was released with crystalline growth.
The phase transition of Copper-tungsten films deposited on Si (100) and Al2O3 substrates took place by means of in situ annealing in vacuum chamber at different temperatures. X-ray diffraction (XRD) and the polarization phase shift technique were employed to characterize the microstructure and residual stress of Cu-W films, respectively. The results indicated that the two successive but distinctive stages of phase transition appeared with the change of annealing temperatures, i.e., W (Cu) solution formation and two-phase crystalline (W and Cu) structure formation. The relationship between phase transition and residual stress was investigated, the tensile stress was caused during phase transition, whereas it was released with crystalline growth.
2007, 36(3):440-444.
Abstract:
The roles of X-ray diffraction and electron diffraction have been reported in crystal structure study of LiCoO2, the cathode materials of lithium ion battery. The crystal structures of the LiCoO2 synthesised at different temperatures and the delithiated product LixCoO2(0
The roles of X-ray diffraction and electron diffraction have been reported in crystal structure study of LiCoO2, the cathode materials of lithium ion battery. The crystal structures of the LiCoO2 synthesised at different temperatures and the delithiated product LixCoO2(0
2007, 36(3):445-449.
Abstract:
采用新型等离子浸没离子注入和沉积（PIIID）法以C2H2为等离子源对NiTi合金进行表面改性。利用Raman光谱分析膜层结构；采用纳米压痕和光电子能谱（XPS）分析涂层前后NiTi合金的表面力学性能和表面成分，利用电化学阻抗谱和动电极化测试涂层前后基体的耐腐蚀性能。结果表明：NiTi合金表面的膜层是DLC：经过PIIID处理后，基体表面由原先的TiOz转变为DLC；纳米硬度和杨式模量得到提高；耐腐蚀性能获得明显改善。
采用新型等离子浸没离子注入和沉积（PIIID）法以C2H2为等离子源对NiTi合金进行表面改性。利用Raman光谱分析膜层结构；采用纳米压痕和光电子能谱（XPS）分析涂层前后NiTi合金的表面力学性能和表面成分，利用电化学阻抗谱和动电极化测试涂层前后基体的耐腐蚀性能。结果表明：NiTi合金表面的膜层是DLC：经过PIIID处理后，基体表面由原先的TiOz转变为DLC；纳米硬度和杨式模量得到提高；耐腐蚀性能获得明显改善。
2007, 36(3):450-453.
Abstract:
用XRD和SEM对Mg-Ni体系燃烧合成产物进行了研究。结果表明：Mg—Ni压坯预热至440℃以上均可热爆合成Mg2Ni，且预热速度越大产物越致密；过大的压坯密度，降低了体系的燃烧温度，影响Mg，Ni间的反应程度；而对于细小的Mg粒，由于较高的燃烧温度，导致合成产物出现严重的烧结现象；此外热爆合成产物在一定温度下适当的保温，有助于提高Mg2Ni的纯度。
用XRD和SEM对Mg-Ni体系燃烧合成产物进行了研究。结果表明：Mg—Ni压坯预热至440℃以上均可热爆合成Mg2Ni，且预热速度越大产物越致密；过大的压坯密度，降低了体系的燃烧温度，影响Mg，Ni间的反应程度；而对于细小的Mg粒，由于较高的燃烧温度，导致合成产物出现严重的烧结现象；此外热爆合成产物在一定温度下适当的保温，有助于提高Mg2Ni的纯度。
2007, 36(3):459-462.
Abstract:
The kinetics of the hydrogen reduction of MoO3 to MoO2 and MoO2 to Mo were investigated. The results showed that the major step of the reduction of MoO3 to MoO2 was controlled by interface-chemical reaction. The apparent activation energy of this step was 58.1 Ll/mol. The major step of the reduction of MoO2 to Mo was controlled by inner diffusion. The apparent activation energy of this step was 30.1 kJ/mol.
The kinetics of the hydrogen reduction of MoO3 to MoO2 and MoO2 to Mo were investigated. The results showed that the major step of the reduction of MoO3 to MoO2 was controlled by interface-chemical reaction. The apparent activation energy of this step was 58.1 Ll/mol. The major step of the reduction of MoO2 to Mo was controlled by inner diffusion. The apparent activation energy of this step was 30.1 kJ/mol.
2007, 36(3):463-466.
Abstract:
Nanostructured bulk of W-Cu alloy was prepared by mechanical alloying and hot pressed sintering. The nanostructured W-Cu material shows the characteristic of the spreading electric arcs, and the commercially used W-Cu alloy exhibits the characteristic of the localized arcs during the electric breakdown. The effect of nanostructured W-Cu alloy is caused by a larger number of electrons emitted during the discharge with a low electron work function, and highly conductive grain boundaries and many nano-metre-scale grains could narrow the potential barrier at the tungsten-copper interface.
Nanostructured bulk of W-Cu alloy was prepared by mechanical alloying and hot pressed sintering. The nanostructured W-Cu material shows the characteristic of the spreading electric arcs, and the commercially used W-Cu alloy exhibits the characteristic of the localized arcs during the electric breakdown. The effect of nanostructured W-Cu alloy is caused by a larger number of electrons emitted during the discharge with a low electron work function, and highly conductive grain boundaries and many nano-metre-scale grains could narrow the potential barrier at the tungsten-copper interface.
2007, 36(3):467-470.
Abstract:
将Zr-Sn-Nb新锆合金样品分组进行不同的热加工，用透射电镜（TEM）和高分辨电镜（HRTEM）观察并分析它们的显微组织和第二相粒子成分。TEM观察发现，1000℃样品与580℃样品相似，第二相粒子呈弥散分布。其它样品中第二相粒子分布不太均匀，随着保温温度升高，带状分布的第二相增多。EDS分析发现样品中存在Nb／Fe比不同的2种Zr-Nb-Fe第二相粒子和不含Fe元素的βNb粒子。
将Zr-Sn-Nb新锆合金样品分组进行不同的热加工，用透射电镜（TEM）和高分辨电镜（HRTEM）观察并分析它们的显微组织和第二相粒子成分。TEM观察发现，1000℃样品与580℃样品相似，第二相粒子呈弥散分布。其它样品中第二相粒子分布不太均匀，随着保温温度升高，带状分布的第二相增多。EDS分析发现样品中存在Nb／Fe比不同的2种Zr-Nb-Fe第二相粒子和不含Fe元素的βNb粒子。
Min Jiahua
,
Sang Wenbin
,
Liu Hongtao
,
Qian Yongbiao
,
Teng Jianyong
,
Fan Jianrong
,
Li Wanwan
,
Zhang Bin
,
Jin Wei
2007, 36(3):471-474.
Abstract:
对电阻率为10^3-6Ω·cm的In掺杂Cd0．9Zn0．1Te晶片在Te气氛和Cd／Zn平衡蒸汽压下进行了热处理，对电阻率为10^8-9Q·cm的非掺杂晶片则在In气氛和Cd／Zn平衡蒸汽压下进行了热处理。结果表明，In掺杂Cd0．9Zn0．1Te晶片经处理后电阻率可提高3个数量级。非掺杂晶片在In气氛中热处理可很容易地改变导电类型，在热处理温度700℃，In分压6．1×10^-4Pa，退火时间达48h后，电阻率可以提高到2．6×10^9Ω·cm。
对电阻率为10^3-6Ω·cm的In掺杂Cd0．9Zn0．1Te晶片在Te气氛和Cd／Zn平衡蒸汽压下进行了热处理，对电阻率为10^8-9Q·cm的非掺杂晶片则在In气氛和Cd／Zn平衡蒸汽压下进行了热处理。结果表明，In掺杂Cd0．9Zn0．1Te晶片经处理后电阻率可提高3个数量级。非掺杂晶片在In气氛中热处理可很容易地改变导电类型，在热处理温度700℃，In分压6．1×10^-4Pa，退火时间达48h后，电阻率可以提高到2．6×10^9Ω·cm。
2007, 36(3):475-479.
Abstract:
The mechanical properties of Ti-6Al-4V alloy by laser rapid forming (LRF) have been investigated. The results show that the mechanical properties of the as-deposited Ti-6Al-4V alloy have the characteristics of higher strength, lower ductility and more distinct anisotropy properties as compared to wrought. The microstructure, content of oxygen and metallurgical flaw of the laser formed samples will have effect on the tensile test results. It is the microstructures that play crucial roles on the mechanical properties, while the oxygen content and ill-bonding flaw are in the next place. For the LRF Ti-6Al-4V alloy with the oxygen content meeting GJB GJB2921-1997, a basket weave microstructure obtained through the solution-aging treatment brings forth the best mechanical properties. Not only the strength but also the ductility is over than that of the wrought specification.
The mechanical properties of Ti-6Al-4V alloy by laser rapid forming (LRF) have been investigated. The results show that the mechanical properties of the as-deposited Ti-6Al-4V alloy have the characteristics of higher strength, lower ductility and more distinct anisotropy properties as compared to wrought. The microstructure, content of oxygen and metallurgical flaw of the laser formed samples will have effect on the tensile test results. It is the microstructures that play crucial roles on the mechanical properties, while the oxygen content and ill-bonding flaw are in the next place. For the LRF Ti-6Al-4V alloy with the oxygen content meeting GJB GJB2921-1997, a basket weave microstructure obtained through the solution-aging treatment brings forth the best mechanical properties. Not only the strength but also the ductility is over than that of the wrought specification.
2007, 36(3):480-483.
Abstract:
A new alloy belonging to Ti-AI-V-Si system has been developed on the base of Ti-6Al-4V, designated as TC4S. Experimental test results show that mechanical properties of TC4S have been improved evidently by proper adjusting the contents of Al and V, adding small amount of Si when compared with conventional Ti-6Al-4V alloy. The satisfied match among the strength, the ductility and the fracture toughness of the alloy has been reached, and meets the requirements of the design. The strength of TC4S alloy can be increased by 60 MPa-100 MPa on the condition of the slight damaging its plasticity and toughness, compared with Ti-6Al-4V ELI.
A new alloy belonging to Ti-AI-V-Si system has been developed on the base of Ti-6Al-4V, designated as TC4S. Experimental test results show that mechanical properties of TC4S have been improved evidently by proper adjusting the contents of Al and V, adding small amount of Si when compared with conventional Ti-6Al-4V alloy. The satisfied match among the strength, the ductility and the fracture toughness of the alloy has been reached, and meets the requirements of the design. The strength of TC4S alloy can be increased by 60 MPa-100 MPa on the condition of the slight damaging its plasticity and toughness, compared with Ti-6Al-4V ELI.
2007, 36(3):484-488.
Abstract:
采用放电等离子烧结（SPS），通过Ti与B4C之间的原位反应合成TiC＋TiB／Ti复合材料。首先通过热力学计算判断可能发生的反应，利用x射线衍射（XRD）、扫描电镜（SEM）对球磨混合粉以及烧结后材料的相组成和显微组织进行了研究，测定材料的相对密度和硬度，并探讨了Ti与B4C采用放电等离子烧结制备TiC＋TiB／Ti复合材料的致密化过程和反应机理。结果表明，采用SPS技术，在1150℃保温5min的条件下，Ti与B4C能同步完成反应、烧结、致密化，生成TiC＋TiB／Ti复合材料，并且原位生成的增强相分布均匀且细小。
采用放电等离子烧结（SPS），通过Ti与B4C之间的原位反应合成TiC＋TiB／Ti复合材料。首先通过热力学计算判断可能发生的反应，利用x射线衍射（XRD）、扫描电镜（SEM）对球磨混合粉以及烧结后材料的相组成和显微组织进行了研究，测定材料的相对密度和硬度，并探讨了Ti与B4C采用放电等离子烧结制备TiC＋TiB／Ti复合材料的致密化过程和反应机理。结果表明，采用SPS技术，在1150℃保温5min的条件下，Ti与B4C能同步完成反应、烧结、致密化，生成TiC＋TiB／Ti复合材料，并且原位生成的增强相分布均匀且细小。
2007, 36(3):489-492.
Abstract:
通过鼠伤寒沙门氏菌回复突变试验（Ames试验）对TLE及TLM2种β型医用钛合金的致突变作用进行生物学评价，试验分别设计5个剂量组、自然回变对照组、溶剂对照组以及阳性对照组，采用平板掺入法在加与不加S9混合液的条件下完成。统计学分析结果显示：2种声型医用钛合金每剂量组各菌株回变菌落数均与自然回变菌落数接近，未超过其2倍，而阳性对照组超过自然回变菌落数的2倍以上。说明TLE，TLM在检测剂量（0．16ul/皿～100ul／皿）范围内反应结果为阴性，即不具有点突变诱变性。
通过鼠伤寒沙门氏菌回复突变试验（Ames试验）对TLE及TLM2种β型医用钛合金的致突变作用进行生物学评价，试验分别设计5个剂量组、自然回变对照组、溶剂对照组以及阳性对照组，采用平板掺入法在加与不加S9混合液的条件下完成。统计学分析结果显示：2种声型医用钛合金每剂量组各菌株回变菌落数均与自然回变菌落数接近，未超过其2倍，而阳性对照组超过自然回变菌落数的2倍以上。说明TLE，TLM在检测剂量（0．16ul/皿～100ul／皿）范围内反应结果为阴性，即不具有点突变诱变性。
2007, 36(3):493-496.
Abstract:
采用拉伸试验、扫描电镜和透射电镜等测试手段，研究了固溶淬火后预变形程度对新型高强Al-Cu-Li-X铝锂合金2A97组织和性能的影响。结果表明：随预变形量增加，135℃时效48h合金强度明显提高，塑性缓慢下降，变形量为4．7％合金的抗拉强度为584MPa，延伸率为12．6％，淬火后的预变形量控制在4％-6％得到比较理想的强塑性匹配。预变形促进基体乃相析出，并使其显著细化和均匀分布。
采用拉伸试验、扫描电镜和透射电镜等测试手段，研究了固溶淬火后预变形程度对新型高强Al-Cu-Li-X铝锂合金2A97组织和性能的影响。结果表明：随预变形量增加，135℃时效48h合金强度明显提高，塑性缓慢下降，变形量为4．7％合金的抗拉强度为584MPa，延伸率为12．6％，淬火后的预变形量控制在4％-6％得到比较理想的强塑性匹配。预变形促进基体乃相析出，并使其显著细化和均匀分布。
2007, 36(3):497-499.
Abstract:
Amorphous melt-spun ribbons of Pr4.2Tb0.3Fe78B17.5 alloy were consolidated into bulk nanocomposite magnets by Spark Plasma Sintering method. Effect of sintering conditions on the density, microstructure and magnetic properties were studied. Higher sintering temperature improved the densification of the magnets, while deteriorated their magnetic properties simultaneously due to the excess crystal grain growth. Magnet possessed a Br of 1.04 T and a JHc of 220 kA/m under the optimal sintering condition, and its microstructure contained satisfied grains with an average size of about 20 nm.
Amorphous melt-spun ribbons of Pr4.2Tb0.3Fe78B17.5 alloy were consolidated into bulk nanocomposite magnets by Spark Plasma Sintering method. Effect of sintering conditions on the density, microstructure and magnetic properties were studied. Higher sintering temperature improved the densification of the magnets, while deteriorated their magnetic properties simultaneously due to the excess crystal grain growth. Magnet possessed a Br of 1.04 T and a JHc of 220 kA/m under the optimal sintering condition, and its microstructure contained satisfied grains with an average size of about 20 nm.
2007, 36(3):500-504.
Abstract:
将AZ91D镁合金铸锭在330℃往复挤压4道次后，在300℃连续正挤压制成Ф5mm的丝材，用OM，SEM分析不同方式挤压前后组织的变化，研究往复挤压及随后正挤压对其组织与性能的影响。研究表明，AZ91D镁合金往复挤压4道次及连续正挤压制备的矽5mm丝材组织均为等轴晶，晶粒尺寸分别为小于10um及1um～3um。经往复挤压及随后的正挤压，AZ91D铸造镁合金的综合力学性能均可得到显著提高，其主要原因是基体组织α-Mg和强化相β-Mg17Al12的细化。往复挤压4道次后，材料真应变高达20．36，正挤压过程中等效应变速率达到0．192s^-1，AZ91D镁合金往复挤压及正挤压晶粒的细化机制主要包括破碎、动态再结晶和动态回复。
将AZ91D镁合金铸锭在330℃往复挤压4道次后，在300℃连续正挤压制成Ф5mm的丝材，用OM，SEM分析不同方式挤压前后组织的变化，研究往复挤压及随后正挤压对其组织与性能的影响。研究表明，AZ91D镁合金往复挤压4道次及连续正挤压制备的矽5mm丝材组织均为等轴晶，晶粒尺寸分别为小于10um及1um～3um。经往复挤压及随后的正挤压，AZ91D铸造镁合金的综合力学性能均可得到显著提高，其主要原因是基体组织α-Mg和强化相β-Mg17Al12的细化。往复挤压4道次后，材料真应变高达20．36，正挤压过程中等效应变速率达到0．192s^-1，AZ91D镁合金往复挤压及正挤压晶粒的细化机制主要包括破碎、动态再结晶和动态回复。
2007, 36(3):505-508.
Abstract:
通过高温热模拟压缩试验和微观组织研究，探索了热变形参数对BT22钛合金内部显微组织的影响。结果表明：BT22钛合金组织对温度敏感，锻造建议在780℃进行，严格控制温升（尤其是终锻温度）。在两相区锻造时，随变形速率的增加，α相尺寸减小。在60％～70％之间存在着晶粒明显细化的临界变形量，这一临界变形量是锻造时必须控制的最小变形量。
通过高温热模拟压缩试验和微观组织研究，探索了热变形参数对BT22钛合金内部显微组织的影响。结果表明：BT22钛合金组织对温度敏感，锻造建议在780℃进行，严格控制温升（尤其是终锻温度）。在两相区锻造时，随变形速率的增加，α相尺寸减小。在60％～70％之间存在着晶粒明显细化的临界变形量，这一临界变形量是锻造时必须控制的最小变形量。
2007, 36(3):509-512.
Abstract:
以MgO为原料、RECl3-KCl-MgCl2为电解质，熔盐电解法制取Al-Mg-RE三元合金。结果表明：RE是由Al直接还原得到，而Mg是由电解得到的：可制得RE含量为0-8％～1．2％，Mg含量为1％-4％的三元合金；电解温度在720℃～780℃之间，电流效率随电解温度的升高而升高，电流效率最高可达到81．3％，但超过780℃，电流效率随电解温度的升高而降低；电流密度在0．8A／cm^2时电流效率最高，过低或者过高的电流密度都可以降低电流效率；电解过程中基本上不产生Cl2。
以MgO为原料、RECl3-KCl-MgCl2为电解质，熔盐电解法制取Al-Mg-RE三元合金。结果表明：RE是由Al直接还原得到，而Mg是由电解得到的：可制得RE含量为0-8％～1．2％，Mg含量为1％-4％的三元合金；电解温度在720℃～780℃之间，电流效率随电解温度的升高而升高，电流效率最高可达到81．3％，但超过780℃，电流效率随电解温度的升高而降低；电流密度在0．8A／cm^2时电流效率最高，过低或者过高的电流密度都可以降低电流效率；电解过程中基本上不产生Cl2。
2007, 36(3):513-516.
Abstract:
Through thermodynamic calculation and experiment analysis, the cause of impurity forming in preparing La1-xSrxMnO3 by self-propagating high-temperature synthesis (SHS) was studied and the suggestion was given in this paper to avoid or diminish it. The results show that La2SrO4 impurity was produced inevitably in the products synthesized by SHS because the Gibbs free energy of La2SrO4 forming reaction is equivalent to that of SrMnO3 forming reaction when MnO2 was adopted as dilution. When La1-xSrxMnO3 was used as dilution, La2SrO4 forming could be avoided. The over-dilution of La1-xSrxMnO3 resulted in Mn3O4 impurity forming, which could be avoided by adjusting the proportion of dilution and controlling the reaction speed and system temperature of SHS process.
Through thermodynamic calculation and experiment analysis, the cause of impurity forming in preparing La1-xSrxMnO3 by self-propagating high-temperature synthesis (SHS) was studied and the suggestion was given in this paper to avoid or diminish it. The results show that La2SrO4 impurity was produced inevitably in the products synthesized by SHS because the Gibbs free energy of La2SrO4 forming reaction is equivalent to that of SrMnO3 forming reaction when MnO2 was adopted as dilution. When La1-xSrxMnO3 was used as dilution, La2SrO4 forming could be avoided. The over-dilution of La1-xSrxMnO3 resulted in Mn3O4 impurity forming, which could be avoided by adjusting the proportion of dilution and controlling the reaction speed and system temperature of SHS process.
2007, 36(3):517-520.
Abstract:
采用粉末冶金法制备高温稀土永磁Sm（Co0.72Fe0．15Cu0.1Zr0．03）7.5，研究了烧结温度对磁体磁性能的影响。结果表明：烧结温度过低，则磁体的致密度较低，难以获得优良的磁性能；烧结温度过高，则Sm挥发，磁体的Sm含量降低，磁性能恶化。磁体的最佳烧结条件为：温度1215℃，保温45min。在上述条件制备的磁体在25℃及500℃时的剩磁夙、内禀矫顽力Hci、最大磁能积（BH）max分别为：0．94T，2276．6kA／m，171．9kJ／m^3及0．67T，509．4kA／m，81.2kJ／m^3；磁体的占．日退磁曲线在500℃时保持为直线，内禀矫顽力温度系数声（25℃-500℃）为-0，16％／℃，最高使用温度达到533℃。
采用粉末冶金法制备高温稀土永磁Sm（Co0.72Fe0．15Cu0.1Zr0．03）7.5，研究了烧结温度对磁体磁性能的影响。结果表明：烧结温度过低，则磁体的致密度较低，难以获得优良的磁性能；烧结温度过高，则Sm挥发，磁体的Sm含量降低，磁性能恶化。磁体的最佳烧结条件为：温度1215℃，保温45min。在上述条件制备的磁体在25℃及500℃时的剩磁夙、内禀矫顽力Hci、最大磁能积（BH）max分别为：0．94T，2276．6kA／m，171．9kJ／m^3及0．67T，509．4kA／m，81.2kJ／m^3；磁体的占．日退磁曲线在500℃时保持为直线，内禀矫顽力温度系数声（25℃-500℃）为-0，16％／℃，最高使用温度达到533℃。
2007, 36(3):521-524.
Abstract:
To avoid the disadvantages resulting from the interface between matrix and reinforcement for metal matrix composites (MMCs), a novel in-situ synthesizing technology, based on powder metallurgy, is presented in this paper. A kind of aluminum matrix composite reinforced by in-situ intermetallic compound fiber was prepared. The results showed that in-situ fiber was distributed uniformly in matrix, parallel to the extrusion direction. Yield strength of in-situ MMCs is 28% and 95.7% higher, respectively than those of ex-situ MMCs and matrix aluminum, and fracture strength is increased by 20.6% and 88.5% correspondingly. The strengthening mechanism of in-situ MMCs is that the excellent interface bonding between the matrix and the reinforcement. The matrix exhibits its strong strength, and the reinforcement exhibits its strong strength. The fracture mechanism of in-situ MMCs is the brittle fracture and cleavage crack of fibers.
To avoid the disadvantages resulting from the interface between matrix and reinforcement for metal matrix composites (MMCs), a novel in-situ synthesizing technology, based on powder metallurgy, is presented in this paper. A kind of aluminum matrix composite reinforced by in-situ intermetallic compound fiber was prepared. The results showed that in-situ fiber was distributed uniformly in matrix, parallel to the extrusion direction. Yield strength of in-situ MMCs is 28% and 95.7% higher, respectively than those of ex-situ MMCs and matrix aluminum, and fracture strength is increased by 20.6% and 88.5% correspondingly. The strengthening mechanism of in-situ MMCs is that the excellent interface bonding between the matrix and the reinforcement. The matrix exhibits its strong strength, and the reinforcement exhibits its strong strength. The fracture mechanism of in-situ MMCs is the brittle fracture and cleavage crack of fibers.
2007, 36(3):525-527.
Abstract:
采用差热分析、显微硬度测试、X射线衍射分析对牙科低金含量银钯合金的时效强化机制进行了初步探讨。结果表明：400℃等温时效20min和459℃等温时效10min样本的显微硬度较ST组样本分别提高了50％和128．5％，600℃等温时效5min组样本显微硬度较ST组样本降低了8％；合金在459℃和600℃有明显CuPd相析出，但是CuPd相与硬度的提高没有联系，合金硬度提高与Cu原子从基质相析出有关。
采用差热分析、显微硬度测试、X射线衍射分析对牙科低金含量银钯合金的时效强化机制进行了初步探讨。结果表明：400℃等温时效20min和459℃等温时效10min样本的显微硬度较ST组样本分别提高了50％和128．5％，600℃等温时效5min组样本显微硬度较ST组样本降低了8％；合金在459℃和600℃有明显CuPd相析出，但是CuPd相与硬度的提高没有联系，合金硬度提高与Cu原子从基质相析出有关。
2007, 36(3):528-532.
Abstract:
利用能谱分析（EDS）、扫描电镜（SEM）和电化学测试等分析手段，研究了以微弧氧化为前处理，以硫酸镍为主盐的镁合金“无氟酸性”化学镀工艺及其镀层性能。结果表明：微弧氧化膜可以有效地防护镁合金，在其表面实现以硫酸镍为主盐的“无氟酸性”化学镀，得到了对环境友好的化学镀新工艺：所得微弧氧化一化学镀层致密、颗粒细小，镀层HV硬度为10195MPa，耐蚀性能显著提高，自腐蚀电位提高为-0．2V左右，钝化区间达800mV左右：化学镀层与镁合金基体结合力明显加强。
利用能谱分析（EDS）、扫描电镜（SEM）和电化学测试等分析手段，研究了以微弧氧化为前处理，以硫酸镍为主盐的镁合金“无氟酸性”化学镀工艺及其镀层性能。结果表明：微弧氧化膜可以有效地防护镁合金，在其表面实现以硫酸镍为主盐的“无氟酸性”化学镀，得到了对环境友好的化学镀新工艺：所得微弧氧化一化学镀层致密、颗粒细小，镀层HV硬度为10195MPa，耐蚀性能显著提高，自腐蚀电位提高为-0．2V左右，钝化区间达800mV左右：化学镀层与镁合金基体结合力明显加强。
2007, 36(3):533-536.
Abstract:
The mechanical properties of SiC Particulate reinforced AZ81 magnesium Base composites prepared by powder metallurgy were studied in the article. The mechanism of mechanical properties was also investigated. The experimental results show that tensile strength, fracture toughness, Vickers hardness of SiCp/AZ81 composites were remarkably improved when a proper volume of SiC were added, their maximum can reach 271.61 MPa, 5.96 MPa-m1/2, 2.52 GPa, respectively.
The mechanical properties of SiC Particulate reinforced AZ81 magnesium Base composites prepared by powder metallurgy were studied in the article. The mechanism of mechanical properties was also investigated. The experimental results show that tensile strength, fracture toughness, Vickers hardness of SiCp/AZ81 composites were remarkably improved when a proper volume of SiC were added, their maximum can reach 271.61 MPa, 5.96 MPa-m1/2, 2.52 GPa, respectively.
2007, 36(3):537-540.
Abstract:
采用粉末注射成形方法制备了钛合金坯体，然后利用溶剂脱脂方法脱除坯体中可溶性粘结剂。通过对溶剂脱脂动力学分析表明，在脱脂过程中，存在动力学控制步骤转化的过程，提出了脱脂临界厚度的概念。当厚度超过5mm时，试样脱脂过程受扩散控制，在常温下进行溶剂脱脂时，其扩散系数为1．86×10^-6cm^2·s^-1，活化能为12．96kJ．mol^-1.K^-1；在厚度小于5mm时，试样脱脂过程受粘结剂溶解和扩散混合控制。
采用粉末注射成形方法制备了钛合金坯体，然后利用溶剂脱脂方法脱除坯体中可溶性粘结剂。通过对溶剂脱脂动力学分析表明，在脱脂过程中，存在动力学控制步骤转化的过程，提出了脱脂临界厚度的概念。当厚度超过5mm时，试样脱脂过程受扩散控制，在常温下进行溶剂脱脂时，其扩散系数为1．86×10^-6cm^2·s^-1，活化能为12．96kJ．mol^-1.K^-1；在厚度小于5mm时，试样脱脂过程受粘结剂溶解和扩散混合控制。
2007, 36(3):541-545.
Abstract:
采用挤压铸造法制备TiB2p／Al复合材料，并借助XRD，SEM，TEM和三点弯曲、摩擦磨损等分析测试手段研究了该材料的组织和性能。结果表明，复合材料组织致密，颗粒分布均匀，相组成主要为Al和TiB2。TEM观察表明，T6态复合材料基体中发现大量细小的β＇析出相和位错。部分界面上存在不连续的块状反应物MgAl2O4。45％TiB2P／Al（体积分数，下同）复合材料的抗弯强度为934MPa，弹性模量为183GPa，比30％TiB2P／Al复合材料的分别提高了34％和28％。常温干摩擦条件下，TiB2P／Al复合材料摩擦系数变化平缓（在0．2左右波动），明显低于铝合金的摩擦系数；且复合材料的磨损表面较为平整、光滑，未观察到大塑性变形，呈现出良好的自润滑性能。
采用挤压铸造法制备TiB2p／Al复合材料，并借助XRD，SEM，TEM和三点弯曲、摩擦磨损等分析测试手段研究了该材料的组织和性能。结果表明，复合材料组织致密，颗粒分布均匀，相组成主要为Al和TiB2。TEM观察表明，T6态复合材料基体中发现大量细小的β＇析出相和位错。部分界面上存在不连续的块状反应物MgAl2O4。45％TiB2P／Al（体积分数，下同）复合材料的抗弯强度为934MPa，弹性模量为183GPa，比30％TiB2P／Al复合材料的分别提高了34％和28％。常温干摩擦条件下，TiB2P／Al复合材料摩擦系数变化平缓（在0．2左右波动），明显低于铝合金的摩擦系数；且复合材料的磨损表面较为平整、光滑，未观察到大塑性变形，呈现出良好的自润滑性能。
2007, 36(3):546-549.
Abstract:
TiB2/Cu matrix Interpenetrating phase composites (IPCs) with high ceramic content (~vol.83%) were prepared adopting high temperature sintering and subsequently melt-infiltration. The morphologies and microstructures of TiB2/Cu IPCs before and after thermal ablation were studied by SEM and EPMA. The thermal shock behavior and ablation-resistance of TiB2/Cu IPCs were investigated using plasma arc heating. The results showed that no crack was found on the ablated surface during the process of instantaneous heating and cooling, which revealed that TiB2/Cu IPCs have a good thermal shock resistance. Melt Cu phase presented obviously a gradual distribution among the ablation zone, transition zone and matrix zone, and no metal phase was detected near the ablation zone, it means that the melt play a role of sweat cooling during elevated temperature. The ablation-resistance mechanisms mainly include sweat cooling, chemical ablation and mechanical denudation.
TiB2/Cu matrix Interpenetrating phase composites (IPCs) with high ceramic content (~vol.83%) were prepared adopting high temperature sintering and subsequently melt-infiltration. The morphologies and microstructures of TiB2/Cu IPCs before and after thermal ablation were studied by SEM and EPMA. The thermal shock behavior and ablation-resistance of TiB2/Cu IPCs were investigated using plasma arc heating. The results showed that no crack was found on the ablated surface during the process of instantaneous heating and cooling, which revealed that TiB2/Cu IPCs have a good thermal shock resistance. Melt Cu phase presented obviously a gradual distribution among the ablation zone, transition zone and matrix zone, and no metal phase was detected near the ablation zone, it means that the melt play a role of sweat cooling during elevated temperature. The ablation-resistance mechanisms mainly include sweat cooling, chemical ablation and mechanical denudation.
2007, 36(3):550-553.
Abstract:
Copper was induced into W powder by electroless, The compacts made from chemical copperplated W powder were infiltrated, and W/15 Cu composites were prepared. The microstructures of the composites were investigated by mean of scanning electron microscope Density, hermeticity and coefficient of thermal expansion were measured. After comparing microstructures and physical property of the W/15Cu made by conventional process, the effects of chemical copperplated W powder on properties of W/15Cu were discussed. The results showed that chemical copperplated W powder could improve the compactibility of W compact, the microstructure and the physical properties of W/15Cu composite. It is indicated that when the compact contains 2% copper, the properties of the material are fairly satisfactory.
Copper was induced into W powder by electroless, The compacts made from chemical copperplated W powder were infiltrated, and W/15 Cu composites were prepared. The microstructures of the composites were investigated by mean of scanning electron microscope Density, hermeticity and coefficient of thermal expansion were measured. After comparing microstructures and physical property of the W/15Cu made by conventional process, the effects of chemical copperplated W powder on properties of W/15Cu were discussed. The results showed that chemical copperplated W powder could improve the compactibility of W compact, the microstructure and the physical properties of W/15Cu composite. It is indicated that when the compact contains 2% copper, the properties of the material are fairly satisfactory.
2007, 36(3):554-558.
Abstract:
Adopting a novel synthesizing method-low temperature reaction melting (LRM), a MgO particulate reinforced magnesium matrix composite was in-situ fabricated using pre-oxidized Mg powders. The microstructures and mechanical properties of the composite were investigated by microstructure observation and tensile tests. The results showed that, due to the melting of Mg powders during LRM treatment, the oxide film on the surface of Mg powder was effectively broken into pieces, refined and subsequently, spheroidized into particulates with micron or sub-micron sizes by the joint effect of the liquid phase Mg and the surface tension of MgO itself. Moreover, The formed MgO particulates possess not only good interfacial bonding with the matrix and uniform distribution, but also high strength and stiffness, which is beneficial to improving the reinforcement effect to the matrix. As a result, the LRM method can bring better microstructures and mechanical properties to the composite compared to powder metallurgy process.
Adopting a novel synthesizing method-low temperature reaction melting (LRM), a MgO particulate reinforced magnesium matrix composite was in-situ fabricated using pre-oxidized Mg powders. The microstructures and mechanical properties of the composite were investigated by microstructure observation and tensile tests. The results showed that, due to the melting of Mg powders during LRM treatment, the oxide film on the surface of Mg powder was effectively broken into pieces, refined and subsequently, spheroidized into particulates with micron or sub-micron sizes by the joint effect of the liquid phase Mg and the surface tension of MgO itself. Moreover, The formed MgO particulates possess not only good interfacial bonding with the matrix and uniform distribution, but also high strength and stiffness, which is beneficial to improving the reinforcement effect to the matrix. As a result, the LRM method can bring better microstructures and mechanical properties to the composite compared to powder metallurgy process.
2007, 36(3):559-564.
Abstract:
Composite electroplating is one of the new methods to produce composite materials, it has been developed rapidly in the last three decades, especially in technology and properties, but the research of its forming mechanism lags behind the research of technology and properties. In this paper, based on the review of enough research works, the general situation research was introduced from the point of view of history and status quo, the main contents and application scope were reviewed, and the mathematical models were presented, as well as the latest progress on composite electroplating mechanism was discussed. Meanwhile, its research direction and developing trends were prospected.
Composite electroplating is one of the new methods to produce composite materials, it has been developed rapidly in the last three decades, especially in technology and properties, but the research of its forming mechanism lags behind the research of technology and properties. In this paper, based on the review of enough research works, the general situation research was introduced from the point of view of history and status quo, the main contents and application scope were reviewed, and the mathematical models were presented, as well as the latest progress on composite electroplating mechanism was discussed. Meanwhile, its research direction and developing trends were prospected.
