Effects of annealing process on electrical conductivity and mechanical property of Cu-Te alloys

1 Introduction Pure copper and copper alloys are widely used due to the high electrical conductivity, high heat transfer, corrosion resistance and excellent formability[1-5]. But the strength of pure copper is low and the strength gained during cold worki…     

7A04-T73铝合金锻件电导率与力学性能稳定性的研究

针对7A04-T73铝合金锻件生产中出现的电导率与力学性能不匹配问题,通过对该合金锻件锻压工艺及热处理工艺的试验研究,确定了影响电导率与力学性能的因素。结果表明,7A04铝合金锻件的最佳锻造温度为400℃～420℃,淬火温度为469℃～475℃,双级时效制度为(115±5)℃8 h+(180±5)℃12 h。     

铝合金的力学性能及其电导率

评述了影响铝合金力学性能和电导率的主要因素，说明铝合金的力学性能与其电导率有一定的关联。介绍了电导率在铝合金热处理工艺制定和力学性能检测中的应用，指出借助于电导率的测定，可以初步推测铝合金的某些力学性能和初步优化铝合金的某些热处理工参数，达到测试快速、无损和简便的目的。     

Preparation of YSZ solid electrolyte by slip casting and its properties

Fully stabilized YSZ solid electrolyte was prepared by slip casting. The density was measured according to the Archimedes principle and the linear shrinkage was calculated from measuring the sizes of samples before and after sintering. XRD analysis was conducted to verify the phase structure of both the starting YSZ powder and the prepared YSZ electrolyte. The microstructure of fracture surface and the electrical properties of the samples sintered at different temperatures were investigated via SEM and a complex impedance method, respectively. By comparison of the properties and features among the samples, a slip casting method was established to be a simple way to manufacture high-quality YSZ electrolyte at the sintering temperature of 1550℃ for 3 h, which provides a new approach for YSZ electrolyte with com-plex shapes and mass production.     

SiO2含量对YSZ陶瓷在高温时效中烧结性的影响

研究了SiO2含量对YSZ陶瓷在不同温度下时效后的烧结速率影响,同时研究了其对YSZ时效过程中的结构形貌和性能变化的影响。实验中以正硅酸乙酯(TEOS)为硅源,制备了SiO2含量不同且有约10%气孔的YSZ陶瓷块体,并在不同温度下热处理180 h。通过扫描电镜(SEM)表征了样品的微观形貌,并使用阿基米德法测试得到样品气孔率,同时表征了样品高温时效后的相组成、力学及热学性能的变化。通过交流阻抗谱法初步判断了SiO2在YSZ陶瓷晶界上的分布。研究发现,0.3%(质量分数,下同)SiO2的引入将会使YSZ晶粒尺寸变大且气孔率显著降低,同时其硬度、杨氏模量及热导率的变化率明显较未添加SiO2的要快。     

合金元素对Cu-Ag合金组织、力学性能和电学性能的影响

采用冷变形及中间热处理方法制备了具有双相纤维复合组织的Cu-Ag合金，研究了成分与组织，性能的关系，随着变形程度的增加，合金强度上升而电导率下降，合金中Ag含量由6％增加至24％时，铸态组织中第二相数量明显增多，变形后能够形成更多的Ag纤维复合相，因而合金强度明显上升，在Cu-6%Ag中添加1％Cr元素可以使合金基体得到进一步强化并在一定程度上细化了Ag纤维相，也可使合金度得到显著改善，在Cu－6%Ag-1%Cr合金中添加微量稀土元素可使Ag纤维分布更为弥散，因而使合金在不降低导电性的同时增加强度，尤其在高强度范围内这种作用更为显著。     

退火工艺对5251铝合金板材组织及性能的影响

从5251铝合金3.0 mm厚度的热轧-中温轧制-冷轧板材切取试料,在箱式退火炉进行不同退火制度的处理,从而研究退火制度对5251铝合金板材的力学性能和电导率的影响,确定了3.0 mm厚5251铝合金板材的合理退火工艺制度,为实际生产该合金板材提供技术支持.     

碳纳米管增强铜基复合材料的制备、力学性能及电导率

以CNTs、电解Cu粉、Cu(CH_3COO)_2·H_2O为原料,采用混酸处理、分子水平法结合行星球磨两步混合工艺制备含0.5%～2%(质量分数)CNTs的Cu基复合粉末,然后通过放电等离子烧结技术制备了Cu-CNTs复合材料,探讨了制备工艺及CNTs含量对Cu-CNTs复合材料的组织、电导率和力学性能的影响规律。结果表明:当CNTs含量小于1.0%时,采用两步混粉工艺制备的Cu-CNTs复合粉体均匀性、分散性良好,经烧结后可获得致密度高、CNTs分布均匀的Cu-CNTs复合材料;当CNTs含量大于1.0%时,复合材料的致密度及CNTs分布均匀性明显降低;随CNTs含量的提高,复合材料的强度先升高后降低,塑性和电导率趋于降低;相对高能球磨、分子水平法等单一混粉工艺而言,两步法制备的Cu-1.0%CNTs复合材料综合性能更优,其电导率为51.7 MS/m(89.1%IACS),维氏硬度为1130 MPa,抗拉强度为279 MPa,断后伸长率为9.8%。     

Characterization of YSZ solid oxide fuel cells electrolyte deposited by atmospheric plasma spraying and low pressure plasma spraying

Yttria doped zirconia has been widely used as electrolyte materials for solid oxide fuel cells (SOFC). Plasma spraying is a cost-effective process to deposit YSZ electrolyte. In this study, the 8 mol% Y₂O₃ stabilized ZrO₂ (YSZ) layer was deposited by low pressure plasma spraying (LPPS) and atmospheric plasma spraying (APS) with fused-crushed and agglomerated powders to examine the effect of spray method and particle size on the electrical conductivity and gas permeability of YSZ coating. The microstructure of YSZ coating was characterized by scanning electron microscopy and x-ray diffraction analysis. The results showed that the gas permeability was significantly influenced by powder structure. The gas permeability of YSZ coating deposited by fused-crushed powder is one order lower in magnitude than that by agglomerated powder. Moreover, the gas permeability of YSZ deposited by LPPS is lower than that of APS YSZ. The electrical conductivity of the deposits through thickness direction was measured by potentiostat/galvanostat based on three-electrode assembly approach. The electrical conductivity of YSZ coating deposited by low pressure plasma spraying with fused-crushed powder of small particle size was 0.043 S cm⁻¹ at 100 °C, which is about 20% higher than that of atmospheric plasma spraying YSZ with the same powder. This article was originally published inBuilding on 100 Years of Success, Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials Park, OH, 2006.     

Research on sintering process of YSZ electrolyte

Yttria stabilized zirconia (YSZ) has widely been used as electrolyte in solid oxide fuel cell (SOFC).The microstructure of YSZ related to the fabrication process was discussed in the paper.With YSZ nano-powders about 40-100 nm as raw material, the YSZ adobe was manufactured by tape calendering process.The named three-step sintering process was performed at 1000 ℃ for 2 h, then raised the temperature with normal rate and as soon as up to 1400 ℃, the furnace was controlled at 1250-1300 ℃ for 10-20 h.The high dense YSZs with the relative density of 96%-99% were obtained; the grain size of YSZ could be reduced to 0.5-3 μm.The above result is benefited to co-fired in the electrode-supported SOFCs.     

Effects of retrogression and reaging heat treatment on the microstructure,exfoliation corrosion,electrical conductivity,and mechanical properties of AA7050

The effects of different retrogression times and temperatures on the microstructure, electrical conductivity, exfoliation corrosion (EXCO), and hardness of the 7050 aluminium alloy were compared with the T6 and T7451 condition. The EXCO solution was prepared in accordance with ASTM G34‐01 standard and the samples were kept in the solution for 48 hr. Corrosion depths were examined by using scanning electron microscope (SEM) in the cross‐sections microstructure of the samples. The effect of EXCO on the material was investigated using stereo optical microscope images. In microstructure investigations, SEM and energy dispersive X‐ray (EDX) analyses were used to determine the distribution and chemistry of the precipitates at the grain boundaries. The results show that retrogression and reaging (RRA) times and temperatures have significant effects on AA7050 EXCO. Especially after 200°C/30 min RRA process, it has been found that 7050 aluminium alloy has higher mechanical strength than T6 level and high corrosion resistance from T7451 level. According to the results of this study, it has been shown that there is a direct connection between electrical conductivity and EXCO.     

变形量和热处理对6060铝合金力学性能和导电率的影响

对530℃固溶处理后的6060铝合金进行了不同变形量下的室温轧制,研究了随后的时效处理温度和轧制变形量对合金微观组织结构、力学性能及导电率的影响。结果表明,合金的强度随轧制变形量的增大而升高,而伸长率有所下降;经70%变形量轧制后于180℃时效处理的合金的综合力学性能和导电率匹配较佳。合金的时效析出过程和微结构演化决定了6060铝合金的导电率和强度。     

Effect of Zr and Sc on mechanical properties and electrical conductivities of Al wires

In order to obtain the Al wires with good mechanical properties and high electrical conductivities, conductive wires of Al–0.16Zr, Al–0.16Sc, Al–0.12Sc–0.04Zr (mass fraction, %) and pure Al (99.996%) were produced with the diameter of 9.5 mm by continuous rheo-extrusion technology, and the extruded materials were heat treated and analyzed. The results show that the separate additions of 0.16% Sc and 0.16% Zr to pure Al improve the ultimate tensile strength but reduce the electrical conductivity, and the similar trend is found in the Al–0.12Sc–0.04Zr alloy. After the subsequent heat treatment, the wire with the optimum comprehensive properties is Al–0.12Sc–0.04Zr alloy, of which the ultimate tensile strength and electrical conductivity reach 160 MPa and 64.03% (IACS), respectively.     

Chemical diffusion and electrical conductivity of Ni3+-xS2

The sulfur activity-composition relation of -Ni_3±xS₂ was determined between 600 and 750°C by thermogravimetry using H₂S/H₂ gas mixtures. The existence of ₁- and ₂-Ni_3±xS₂ was confirmed. The chemical diffusion coefficient of -Ni_3±xS₂ was measured as a function of composition at 650°, 700°, and 750°C using thermogravimetry for the reequilibration reaction. The chemical diffusion coefficients varied with composition and showed a maximum at stoichiometric composition, Ni₃S₂. The activation energy for chemical diffusion was determined as E_a=31.3 Kcal·mole^–1 for stoichiometric Ni₃S₂. Electrical conductivity of -Ni_3+-xS₂ was determined as a function of composition at 650°C. The electrical conductivity increased with increasing the mole fraction of sulfur. The temperature dependence of the electrical conductivity of Ni₃S₂ was measured between 50 and 750°C and found to exhibit metallic behavior.     

稀土元素对工业纯铝导电性的影响

研究了稀土元素对工业纯铝导电性的影响。结果表明：混合稀土对工业纯铝的导电性没有改善作用;在一定的数量范围内纯稀土元素镧、铈的加入,对铝的常温导电性有一定的改善作用,高温时则使电阻率略微上升。还对镧、铈降低铝常温电阻率的机理作了初步的探讨。     

7055铝合金的时效硬化特性与电导率

研究了不同时效制度下7055铝合金硬度及电导率的变化规律,分析了化学成分对7055铝合金时效峰推迟的影响。     

富Ce混合稀土加入量对铝合金组织与导电性能的影响

通过金相显微镜(OM)、扫描电镜(SEM)、室温导电率及高温电阻率测试等方法研究富Ce混合稀土对铸态及均匀化态铝合金组织与导电性能的影响。结果表明:富Ce混合稀土对铝合金组织具有细化、变质和净化的作用,加入量为0.10%时细化效果最好;随着富Ce混合稀土加入量的增加,细化效果逐渐减弱,但对含铁杂质相的变质作用加强,导电率逐渐升高,加入量为0.30%时,导电率达到62.10%IACS;合金在570℃均匀化24 h后导电率整体上升,富Ce混合稀土加入量为0.30%时,导电率达到62.30%IACS;富Ce混合稀土对铝合金的高温导电性能有不利影响,加入量越多,合金在高温下的电阻率越大,通过均匀化处理可以减小合金的高温电阻率,降低合金电阻率对温度的敏感性。     

中间退火对镁合金板材组织和性能的影响

研究AZ31B镁合金轧制道次间不同退火温度和时间对板材微观组织和力学性能的影响,分析了拉伸试样断口形貌.实验结果表明,退火处理后镁合金板材由轧制纤维组织转变为均匀等轴的再结晶组织,退火再结晶的起始温度为200℃;退火后的力学性能得到一定程度的恢复,硬度、屈服强度最大降幅分别为25.4%和37.1%,伸长率最大增幅达31.3%,拉伸断口由解理和韧窝混合断口转变为典型韧性断口.实验得到镁合金中间退火的较佳工艺为:退火温度300～320℃,退火时间60～120 min.     

多重时效析出第二相对Al-Mg-Si合金电导率的影响

电导率的变化能够灵敏地反应Al-Mg-Si合金的时效析出过程,然而溶质原子及时效析出第二相对电导率的单独影响尚不清楚。Al-Mg-Si合金中含有3种成分和形貌不同的第二相。通过实验及模型化系统地研究Al-Mg-Si合金中多重析出第二相对其电导率的影响。结果表明:由于棒状β″相或针状β′相能够分别在473和523 K时有效地阻碍传导电子的移动,因此Al-Mg-Si合金的电导率主要依赖于棒状β″相(T=473 K)或针状β′相(T=523 K)的影响。模型预测结果与实验结果吻合良好,验证了模型的有效性。     

激光冲击处理对304不锈钢力学性能的影响

选用不同涂层对304不锈钢板材激光冲击处理,研究了自主研制的硅酸乙脂涂层与几种常用吸收涂层对304不锈钢的硬度和表面残余应力等冲击力学性能的影响.结果表明,在激光冲击过程中,黑漆涂层、铝箔涂层和硅酸乙脂黑漆涂层都能有效提高激光冲击试样的表面硬度,激光连续冲击后,在304不锈钢试件表面能形成1mm厚的硬化层,其表面硬度最大到240HV;随着激光功率密度的增强,其表面硬度逐渐增强;其表面残余应力也随着激光功率密度的增加而逐渐增大.