爆炸压实法制备纳米氧化铝弥散强化铜

提出了一种制备优质廉价纳米氧化铝弥散强化铜的新工艺。首先采用机械合金化法制备氧化铝和铜的混合粉末,然后经过氢气还原烧结后得到氧化铝-铜的多孔体,最后采用爆炸压实方法制得氧化铝-铜块体初坯。检测结果表明,采用该工艺制得的氧化铝-铜初坯的相对密度达到了98%以上,纳米氧化铝颗粒均匀地弥散分布在铜基体中,很好地提高了材料的硬度与强度。

铜-铝-氧化铝复合多孔材料的制备及性能

以NaC l为造孔剂制作铜-铝-氧化铝复合多孔材料,制备过程不需要用真空或复杂的装置,是一种既廉价又高效的方法。对烧结后的样品进行SEM、XRD分析,同时,对添加造孔剂与未加造孔剂的样品的孔隙率、抗压强度以及硬度进行了计算和测试。结果表明,不同成分配比会影响复合材料的物相、孔隙率及力学性能。将造孔剂去除前、后的样品相比,两者孔隙率相差10%左右,力学性能相差很大,抗压强度从2.63 MPa变化到17.64 MPa。

预制体浸渗法苎麻纤维遗态Al_2O_3-Cu制备工艺对性能的影响

利用预制体浸渗法制备苎麻纤维织物遗态结构Al2O3-Cu复合材料,分析氧化浸渍次数、还原烧结温度对复合材料物理性能、显微组织和断裂特征的影响。结果表明,随着氧化浸渍次数的增加和还原烧结温度的升高,试样浸渍率升高,显气孔率下降,拉伸性能逐步改善。二次氧化浸渍,1 020℃还原烧结成型试样,浸渍率81. 58%,显气孔率30. 84%,拉伸强度10. 73 MPa。一次氧化浸渍还原烧结试样主要发生的是脆性断裂,二次氧化浸渍还原烧结试样拉伸断裂主要形式是沿晶断裂、穿晶断裂以及晶粒的拔出。

Cu-ZnO-Al_2O_3-ZrO_2/HZSM-5催化剂上CO_2加氢合成二甲醚

采用共沉淀法和机械混合法合成了Cu-ZnO-Al2O3-ZrO2/HZSM-5双功能催化剂,研究了该催化剂催化CO2加氢合成二甲醚反应的性能,考察了HZSM-5分子筛的硅铝比、反应温度和反应压力对CO2转化率、二甲醚选择性和收率的影响。实验结果表明,随硅铝比的增大,二甲醚选择性和收率呈峰形变化特性;随反应温度的升高,CO2转化率增加,二甲醚选择性降低;而随反应压力的升高,二甲醚选择性增加。当硅铝比(n(SiO2)∶n(Al2O3))为50、反应温度和压力为250℃和3.0 MPa时,CO2转化率达到19.6%,二甲醚的选择性和收率分别为47.0%和9.2%。H2-TPR,NH3-TPD,XRD表征结果显示,Cu-ZnO-Al2O3-ZrO2/HZSM-5双功能催化剂中HZSM-5分子筛的结构没有明显变化,但硅铝比的变化影响双功能催化剂的酸性,HZSM-5分子筛的加入使Cu的还原温度降低。

Preparation of copper nano-wires by template synthesis method

Highly ordered and porous anodic aluminum oxide templates were prepared. The ordered copper nanowires arrays were assembled in nano-holes of the template by alternating current electrodeposition at lover voltage. The morphologies of template and copper nano-wires arrays were characterized by means of field emission scanning electron microscope (FESEM) and the crystal structure of copper nano-wires was determined by means of X-ray diffraction. The results indicate that copper nano-wires hold the preferred crystalline orientation along (111), (200), (220) and (331) crystal faces during growth, and the growth of copper nano-wires in the nano-holes of the template is homogenous and continuous.

Current Efficiency, Corrosion and Structural Changes in SnO2-Sb2O3-CuO Inert Anodes for Aluminium Electrolysis

A systematic study was conducted on current efficiency （CE）, corrosion and structural changes in SnO2-based inert anodes （made of 96wt%SnO2＋2wt%Sb2O3＋2wt%CuO） on a laboratory Hall-Heroult aluminium cell. The influence of operating parameters and electrolyte composition on the CE and corrosion process were evaluated. The CE was found to be more than 90% and catastrophic corrosion took place at low percent of Al2O3, high percent of LiF, low cryolite ratio and high current densities. From all the structural changes that took place in the SnO2-based inert anodes, we assumed that the most important contribution was due to the migration of CuO towards the outer limits of the constituent grains of SnO2 based ceramic. The complex process occurred during the formation of various phases and their sintering ability both directly depended on Cu/Sb molar ratio.

Removal of Cu(Ⅱ) from Aqueous Solution Using a Novel Crosslinked Alumina-Chitosan Hybrid Adsorbent

A novel biosorbent was developed by coating chitosan, a naturally and abundantly available biopolymer, on to activated alumina based on oil shale ash via crosslinking. The adsorbent was characterized by various techniques, such as Fourier transform infrared spectroscopy, scarming＇ elec.tron micros cop.y, the rmogravimetric-differentialthermal analysis, and X-ray photoelectron spectroscope. Batch isothermal equilibrium adsorption experiments were condcted to evaluate the adsorbent for the removal of Cu（Ⅱ） from wastewater. The effect of pH and agitation time on the adsorption capacity was also investigated, indicating that the optimum pH was 6.0. The equilibrium adsorp-tion data were correlated with Langmuir and Freundlich models. The maximum monolayer adsorption capacity of chitosan coated alumina sorbent as obtained from Langmuir adsorption isotherm was fotmd to be 315.46 mg.g-1 for Cu（Ⅱ）. The adsorbent loaded with Cu（Ⅱ） was readily regenerated using 0.1 mol.L-1 sodium hydroxide solution. All these indicated that chitosan coated alumina adsorbent not only have high adsorption activity, but also had good stability in the wastewater treatment process.

Effect of sub-layer thickness on magnetic and giant magnetoresistance properties of Ni–Fe/Cu/Co/Cu multilayered nanowire arrays

Ni-Fe/Cu/Co/Cu multilayered nanowire arrays were electrodeposited into anodic aluminum oxide template by using dual-bath method at room temperature. Scanning electron microscopy and transmission electron microscopy were used to characterize the morphology and structure of the multilayered nanowire arrays. Vibrating sample magnetometer and physical property measurement system were used to measure their magnetic and giant magnetoresistance （GMR） properties. The effect of sub-layer thickness on the magnetic and GMR properties was investigated. The results indicate that magnetic properties of electmdeposited nanowires are not affected obviously by Cu layer thickness, while magnetic layers （Ni-Fe and Co layers） have significant influence. In addition, GMR ratio presents an oscillatory behavior as Cu layer thickness changes. The magnetic and GMR properties of the multilayered nanowire arrays are optimum at room temperature for the material structure of Ni-Fe （25 nm）/Cu （15 nm）/Co （25 nm）/Cu （15 nm） with 30 deposition cycles.

用热还原生成法制备自生Al_2O_3/Cu基复合材料

用热还原生成法制备了自生Al_2O_3-Cu复合材料,并从化学反应热力学和动力学的角度,对Cu_2O-Al二元体系反应过程进行了研究,同时通过SEM、X-ray等手段,对所制得的材料进行了分析,结果表明, 用此方法制备此复合材料是可行的。

催化裂化轻汽油深度脱硫吸附剂的研制及性能

采用等体积浸渍法制备了一系列Ni-Cu/ZnO-Al2O3脱硫吸附剂,考察了不同金属活性组分及其负载量、不同助剂及其负载量、焙烧温度等因素对催化裂化轻汽油中噻吩脱除性能的影响,并采用XRD、压汞技术对制备的吸附剂进行表征。表征结果显示,500℃下焙烧制得的Ni-Cu/ZnO-Al2O3吸附剂的比表面积最大,表现出较高的脱硫活性,其中,NiO为Ni-Cu/ZnO-Al2O3吸附剂脱除噻吩硫的主要活性组分。实验结果表明,在Ni负载量为6%(w)、Cu含量为5%(w)、焙烧温度为500℃、反应温度为350℃、压力为0.6 MPa、液态空速2 h-1条件下,Ni-Cu/ZnO-Al2O3吸附剂的饱和硫容为1.70%。

High temperature mechanical behavior of alumina dispersion strengthened copper alloy with high content of alumina

The microstructure and its effects on the high temperature mechanical behavior of Cu-2.7%Al_2O_3 （volume fraction） dispersion strengthened copper （ADSC） alloy were investigated. The results indicate that fine alumina particles are uniformly distributed in the copper matrix, while a few coarse ones are distributed on the grain boundaries. Tensile tests results show that Hall-Petch mechanism is the main contribution to the yield strength of ADSC alloy at room temperature. Its high temperature strength is attributed to the strong pinning effects of alumina particles on the grain and sub-grain boundaries with dislocations. The ultimate tensile strength can reach 237 MPa and the corresponding yield strength reaches 226 MPa at 700℃. Tensile fracture morphology indicates that the ADSC alloy shows brittleness at elevated temperatures. Creep tests results demonstrate that the steady state creep rates at 400 ℃ are lower than those at 700 ℃. The stress exponents at 400 ℃ and 700℃ are 7 and 5, respectively, and the creep strain rates of the ADSC alloy are controlled by dislocation core diffusion and lattice diffusion.

Plasma electrolytic oxidation behavior and corrosion resistance of brass in aluminate electrolyte containing NaH2PO4 or Na2SiO3

Plasma electrolytic oxidation(PEO) of brass was carried out in aluminate electrolytes with the addition of NaH2PO4(S1) and Na2SiO3(S2), respectively, with the aim to investigate the effect of additives on the coating formation and corrosion resistance. For the PEO in S1 electrolyte, a mixed layer of AlPO4and Al2O3is formed at the initial stage, which leads to fast plasma discharges and formation of black coatings with the compositions of Al2O3,CuO, Cu2O and ZnO. However, in S2 electrolyte, plasma discharges are delayed and the coatings show a reddish color due to more Cu2O. Mott-Schottky tests show that the S1 coatings are p-type semiconductors;while the S2 coatings can be adjusted between n-type and p-type. Potentiodynamic polarization and electrochemical impedance spectroscopy(EIS) tests show that the PEO treatment can significantly improve the corrosion resistance of brass, with protection efficiency up to 91.50% and the largest charge transfer resistance of 59.95 kΩ·cm^(2) for the S1 coating.

Effect of reduction-oxidation treatment on structure and catalytic properties of ordered mesoporous Cu-Mg-Al composite oxides

Ordered mesoporous Cu-Mg-A1 composite oxides were synthesized via the one-pot evaporation-in- duced self-assembly strategy. Using this method, copper was first homogeneously incorporated into the ordered mesoporous spinel matrix. After H2 reduction treatment, according to X-ray diffraction （XRD） and transmission electron microscopy （TEM） results, copper existed as metallic nanoparticles with the size of 6-10 nm that well decorated the parent mesoporous skeleton. The metallic nanoparticles were then re-oxidized to copper oxide when exposed to air or during CO oxidation reaction at low temperatures. Thus, copper migrated from bulk spinel phase to the surface after the reduction-oxidation treat- ment. Moreover, the copper on the surface was re-incor- porated into the bulk spinel phase by further thermal treatment at much higher temperature in the presence of air. The correlation between the state of copper in the mesoporous composite oxides and the catalytic perfor- mance toward CO oxidation was studied. It was found that copper existed as oxide nanoparticles on the surface of mesoporous Mg-Al skeleton is much more active than that existed as lattice Cu ions in spinel phase.

Thermally Radiative Rotating Magneto-Nanofluid Flow over an Exponential Sheet with Heat Generation and Viscous Dissipation:A Comparative Study

This article examines a mathematical model to analyze the rotating flow of three-dimensional water based nanofluid over a convectively heated exponentially stretching sheet in the presence of transverse magnetic field with additional effects of thermal radiation,Joule heating and viscous dissipation.Silver(Ag),copper(Cu),copper oxide(Cu O),aluminum oxide(Al_2O_3)and titanium dioxide(Ti O_2)have been taken under consideration as the nanoparticles and water(H_2O)as the base fluid.Using suitable similarity transformations,the governing partial differential equations(PDEs)of the modeled problem are transformed to the ordinary differential equations(ODEs).These ODEs are then solved numerically by applying the shooting method.For the particular situation,the results are compared with the available literature.The effects of different nanoparticles on the temperature distribution are also discussed graphically and numerically.It is witnessed that the skin friction coefficient is maximum for silver based nanofluid.Also,the velocity profile is found to diminish for the increasing values of the magnetic parameter.