纳米多孔镍基催化材料的结构与催化性能

用快速凝固技术制备了NiAl合金条带,经 5min球磨、在m(NaOH)∶m(H2O) =1∶4的溶液中活化处理 3h,得纳米多孔骨架镍催化剂。用XRD、SEM、AFM等对其微观组织结构进行了分析,其变化规律是:随着快淬速度的增加,合金中有效相的含量增加,晶粒变细,甚至部分非晶化;脱铝后的催化剂主要由疏松多孔的棉絮状结构和吸附在孔内的纳米级镍晶粒组成,孔径大小及分布均匀,晶粒尺寸大多在 80nm左右。将其用于呋喃加氢催化反应,在相同催化剂用量条件下,使原来在骨架镍催化下需 0 .40MPa压力才能完成的加氢反应降为 0. 25MPa即可在相同的时间内完成,反应温度还下降 2℃。     

纳米CdSe_xS_(1-x)微晶玻璃的光吸收性能

半导体纳米微晶掺杂滤光玻璃由于具有优异光学性质 ,近年来已成为光电子材料科学与技术关注的焦点之一。以硼硅酸盐玻璃为基质 ,通过对掺杂微晶组成、结构的设计以及颗粒尺寸的控制 ,系统的研究了纳米微晶的组成、结构以及纳米颗粒尺寸效应等因素对玻璃光吸收性能的影响。结果表明 ,玻璃吸收曲线的截止波长位置以及截止吸收系数主要取决于半导体纳米CdSexS1-x微晶的组成 ,吸收曲线的斜率取决于纳米微晶的颗粒尺寸分布     

电磁分离一次铝硅合金中的富铁相

一次铝硅合金(含铁5wt%)加锰并在电磁场中进行定向凝固去除合金中的富铁相,主要通过改善富铁相的形态和降低合金中的铁含量减弱富铁相对铝硅合金性能的影响,研究了不同锰添加量下铝硅合金的电磁除铁效率、锰对富铁相形态改善的影响及电磁加锰分离富铁相的机理。结果表明,随锰添加量增大,铝硅合金中的富铁相逐渐从有害的针状转变为骨骼状、块状。加锰并经电磁定向凝固处理后,铝硅合金中绝大部分富铁相的形态变得规则,并在电磁力驱动下富集至合金底部。当锰铁摩尔比为1.2时,铝硅合金中残留的铁含量降至0.39wt%,加锰电磁除铁的效率高达90%。     

凝固冷却方式对CoCrFeNiMn高熵合金的影响

高熵合金由于其独特的设计思路及优秀的性能。在表面技术领域有较强的应用前景。本文选用了三种不同的冷却方式(铸造凝固(Cast Solidification)、水淬凝固(Water Quenching Solidification)和雾化凝固(Atomization Solidification)对铝热反应制备的CoCrFeNiMn高熵合金熔体进行冷却,采用XRD、SEM和EDS技术对合金的相结构、微观组织进行了表征,同时采用HVS＿1000A维氏硬度仪测试了合金的硬度。结果表明：在不同的凝固冷却方式下,CoCrFeNiMn高熵合金的相结构主要由FCC+BCC两相组成,其中在水淬试样中产生了过渡的FCC相;合金的晶粒尺寸随着冷却速率的提高而减小,雾化试样的晶粒尺寸最小,为18.1μm²;合金硬度随着冷速的提高而逐步提高,雾化试样的硬度最高,达到了704.8HV。     

NiAl—Fe新型复合材料的制备与研究

NiAl-Fe复合材料具有很优良的高温抗氧化能力和防腐、耐磨性能。以反应熔铸技术制备的NiAl—Fe复合材料为试验对象,研究了不同铁含量的复合材料的相组成、微观结构和成分,并对其抗氧化性能、耐腐蚀性能、抗磨损性能进行了对比试验。试验结果表明：采用反应熔铸技术可获得性能优良的NiAl一Fe基金属间化合物,具有工程应用前景。     

MgO含量对RSCAF体系微晶玻璃析晶行为的影响

采用MgO取代R₂O-SiO₂-CaO-Al₂O₃-F(RSCAF)体系中的部分CaO制备了微晶玻璃,系统研究了MgO含量对该微晶玻璃析晶行为的影响。结果表明,RSCAF体系中不含MgO时(CaO含量为16.5%,质量分数,下同),经过热处理后微晶玻璃的主晶相为硅碱钙石,微观形貌中结晶相呈犬牙交错状,微晶玻璃的密度小于基础玻璃。当RSCAF体系中MgO的含量为0%~3%时,微晶玻璃的结晶度随着CaO含量的减少而降低;随着体系中MgO含量的进一步增加以及CaO含量的减少,微晶玻璃的主晶相由硅碱钙石逐渐向透辉石转变,微观形貌中呈柱状、片状的透辉石相增多,密度也逐渐增加;当体系中MgO的含量增加到4%(CaO含量降低至12.5%)时,微晶玻璃的主晶相完全转变为透辉石,且透辉石的结晶度相对主晶相为硅碱钙石时有所增加,微晶玻璃的密度大于基础玻璃。     

高品质超低膨胀透明微晶玻璃实现批量化生产

锂铝硅系超低膨胀微晶玻璃是一种性能优良的低膨胀光学材料,热膨胀系数低、透明性好。国产高品质超低膨胀微晶玻璃一直受到技术制约,难以批量化生产。本研究采用熔融法结合搅拌工艺以及适宜的热处理制度,成功批量化生产出热膨胀系数接近于零的高品质超低膨胀透明微晶玻璃产品,产品外观完整,内部基本无气泡、条纹等缺陷。对优级产品进行热膨胀系数、应力双折射、抗弯强度测试,结果表明,优级产品热膨胀系数为1.6×10^-8 K^-1,应力双折射小于2 nm/cm,抗弯强度高达171 MPa,品质已达到ZERODUR零级。采用XRD、SEM、TEM等手段对该产品的物相组成、表面形貌、微观结构进行了分析研究,产品主晶相为β-石英固溶体,晶相含量较高且分布均匀,晶粒尺寸为几十纳米,保证了其极低的热膨胀系数和高透明性。     

Be元素对TiAl合金铸态组织及硬度的影响

本文利用非自耗电弧熔炼设备制备了Ti-xAl-yBe(x=43,45,47,49;y=1,3,5,7,9)三元合金,对其铸态组织的演化规律及其硬度进行了研究。研究发现,当Be含量为1at.%时,随着Al含量的增加,其铸态组织演化过程如下:粗大的板条脆硬相→混合组织(粗大的板条脆硬相+枝晶组织)→枝晶组织。当Be含量为9at.%时,其铸态组织由混合组织向发达的枝晶组织转变。由Ti-49Al-9Be合金的枝晶形态可知,其凝固初生相为β相。通过硬度测试可知,Al含量小于45at.%的TiAl基合金的硬度变化有逐渐减小的趋势,而Al含量大于47at.%的合金的硬度变化有逐渐递增的趋势,这主要与其凝固组织的形态和相组成有关。     

电镀Fe-Cr-Ni及Fe-Ni合金相组成研究

用x-射线衍射法测定了Fe-cr-Ni合金镀层及Fe-Ni合金镀层的相组成。这些合金镀层的相组成很复杂。一般含有Cr、Fe碳化物、富Cr、富Ni、富α-Fe及γ-NiFe相。在Fe-Cr-Ni合金镀层中,Fe含量80％左右时,合金含(Cr、Fe)_7C_3,相。当合金中Ni的含量增加时,富Ni相消失,而合金中Cr含量增加时有Fe-cr相形成。这种不形成均匀固溶体合金相的现象称为相分离。     

利用高炉渣及粉煤灰制备废渣微晶玻璃的研究

利用高炉渣及粉煤灰为主要原料,采用直接烧结法制备废渣微晶玻璃,利用差热分析(DSC)、X射线衍射(XRD)、扫描电镜(SEM)等分析手段,结合力学性能测试,讨论了粉煤灰含量对微晶玻璃晶相组成和性能的影响.结果表明:当粉煤灰含量较高时,微晶玻璃的主晶相为钙镁黄长石,副品相为透辉石;较高的粉煤灰含量有利于透辉石的生成,随着粉煤灰含量的减少微晶玻璃晶相逐渐变为钙镁黄长石;由于粉煤灰引入了较多的残余碳粒及硫,当粉煤灰含量较高时会导致微晶玻璃性能下降;当高炉渣含量为90wt％,粉煤灰含量为10wt％时,制备的微晶玻璃性能最好,其主晶相为钙镁黄长石,各项性能均优于其它建材.     

成分对汽车用（La0.7Mg0.3）Nix合金储氢特性的影响

为开发出具有高循环寿命和高储氢性能的新能源汽车用稀土镁基储氢合金,考察了铸态和退火态的铸锭/快淬（La_0.7Mg_0.3）Ni_x（x=2.0、2.5、3.0）储氢合金的微观结构、物相组成和储氢特性。结果表明,当x=2.5时快淬法储氢合金具有较好的吸放氢平台压力,PCT曲线中体现出完全脱氢特征,吸氢容量约为1.44%（质量分数）。经过850~950 ℃退火处理,铸锭法（La_0.7Mg_0.3）Ni_2.5储氢合金相较（La_0.7Mg_0.3）Ni_2.0储氢合金具有更高的吸放氢平台压和更宽的吸放氢平台,表明前者具有相对更好的吸放氢性能;不同退火温度下（La_0.7Mg_0.3）Ni_2.5储氢合金的吸放氢平台压较为接近,吸氢和放氢容量可达到1.6%（质量分数）。铸锭法和快淬法（La_0.7Mg_0.3）Ni_x储氢合金中的LaNi₅和（LaMg）Ni₃相会随着退火温度的升高而逐渐转变为（LaMg）₂Ni₇相;铸锭法和快淬法（La_0.7Mg_0.3）Ni_2.5储氢合金的表面粉末颗粒分别在退火温度为950 ℃和900 ℃时最为细小。     

High-speed jet electrodeposition and microstructure of nanocrystalline Ni-Co alloys

The jet electrodeposition from watts baths with a device of electrolyte jet was carried out to prepare nano-crystalline cobalt-nickel alloys. The influence of the concentration of Co²⁺ ions in the electrolyte and electrolysis parameters, such as the cathodic current density, the temperature as well as the electrolyte jet speed, on the chemistry and microstructure of Ni-Co-deposit alloys were investigated. Experimental results indicated that increasing the Co²⁺ ions concentration in the bath, the electrolyte jet speed and decreasing of the cathodic current density and decrease of the electrolyte temperature all results in an increase of cobalt content in the alloy. Detailed microstructure changes upon the changes of alloy composition and experimental conditions were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD results show the Ni-Co solid solution was formed through the jet electrodeposition. Phase constitution of solid solution changes progressively under different electrolyte concentration. Alloys with low Co concentration exhibit single phase of face-centered cubic (fcc) structure; The Co concentration over 60.39 wt.%, the alloys are composed of face-centered cubic (fcc) phase and hexagonal close-packed (hcp) phase. Furthermore, the formation of the nanostructured Ni-Co alloy deposit is investigated. Increasing the Co²⁺ ions concentration in the bath, the cathodic current density, the electrolyte temperature and the electrolyte jet speed all result in the finer grains in the deposits. Additives such as saccharin in the electrolyte also favor the formation of the finer grains in the alloy deposits.     

Activity–Composition Relations in Platinum–Chromium and Platinum–Vanadium Alloys at 1500°C

Activity–composition relations in Pt–Cr and Pt–V alloys at 1500°C were determined from equilibration of these alloys with Cr₂O₃ and V₂O₃, respectively, in Co₂–H₂ atmospheres of known oxygen partial pressures, followed by quenching to room temperature and microprobe analyses of the quenched alloys. The activities of Cr and V were calculated from known standard free energies of formation of Cr₂O₃ and V₂O₃ from the respective elements, and the oxygen pressures were calculated from the C–H–O equilibrium in the gas phase. Both alloy systems show strong negative deviations from Raoultian behavior.     

Corrosion performance of NiAl intermetallic with Mo,Ga and Fe in neutral and alkaline media

The corrosion resistance of mechanically alloyed NiAl intermetallics with additions of Mo, Ga and Fe, and their combinations, has been studied using potentiodynamic polarization curves and linear polarization resistance tests at room temperature. Solutions included 0.5 m NaCl and 0.5 m NaOH. The Al–42Ni+6Fe and Al–40Ni+6Fe+2Mo alloys exhibited the best corrosion resistance in NaCl whereas the highest corrosion rate was observed on Al–39Ni+6Fe+6Mo alloy, above the NiAl-base alloy. In NaOH, the highest corrosion rate was exhibited by Al–41Ni+6Mo alloy, whereas the best corrosion performance was obtained by alloys with 6Ga, followed by alloys containing 6Fe+2Ga and/or 2Mo+2Ga, and NiAl-base alloy had an intermediate corrosion rate. The alloys with the lowest corrosion rate also had the lowest pitting potential values. So, generally speaking, additions of 6Mo decreased the corrosion resistance of NiAl-base alloys in these environments. The results were supplemented by detailed scanning electronic microscopy studies and chemical microanalysis of the corroded specimens.     

Electrodeposition and characterization of Zn–Ni alloys as sublayers for epoxy coating deposition

The chemical composition and phase structure of Zn–Ni alloys obtained by electrodeposition under various conditions were investigated. The influence of the deposition solution and deposition current density on the composition, phase structure, current efficiency and corrosion properties of Zn–Ni alloys were examined. It was shown that the chemical composition and phase structure affect the anticorrosive properties of Zn–Ni alloys. A Zn–Ni alloy electrodeposited from a chloride solution at 20 mA cm^–2 exhibited the best corrosion properties, so this alloy was chosen for further examination. Epoxy coatings were formed by cathodic electrodeposition of an epoxy resin on steel and steel modified with a Zn–Ni alloy. From the time dependence of the pore resistance, coating capacitance and relative permittivity of the epoxy coating, the diffusion coefficient of water through the epoxy coating, D(H₂O), and its thermal stability, it was shown that the Zn–Ni sublayer significantly affects the electrochemical and transport properties, as well as the thermal stability of epoxy coatings. On the basis of the experimental results it can be concluded that modification of a steel surface by a Zn–Ni alloy improves the corrosion protection of epoxy coatings.     

镍基非晶态合金加氢催化剂与磁稳定床反应器的开发与工业应用

报道了开发镍基非晶态合金加氢催化剂的实验室研究、中试研究及工业应用研究结果。向非晶态合金中加入少量原子半径大的其他元素，使非晶态合金的晶化温度由360℃提高到520℃；在含镍非晶态合金中加入铝，然后用碱将铝抽出，使非晶态合金比表面积由1m^2/g增加到100m^2/g以上；在建立30t/a非晶态合金生产示范装置中，自行设计了特殊的喷嘴和选用适宜的坩埚材质，使生产成品率由20％左右提高到95％以上，利用副产的偏铝酸钠，合成NaY分子筛，形成了整体的清洁生产过程；重点介绍了非晶态合金加氢催化剂经在三个工厂工业应用成功，三项工业应用成果每年为企业创造直接效益6700万元。还报道了对磁稳定床反应器的研究开发，经在20kt/a磁稳定床加氢示范装置上3500h试验，其生产效率比釜式加氢过程提高4倍，催化剂消耗减少50％。     

Hydrogen Evolution and Hydrogen Oxidation on Palladium Bismuth Alloys

Thin film alloys of PdBi have been synthesised using a high throughput physical vapour deposition method to produce compositional gradients of PdBi alloys. XPS indicates that for the non-equilibrated thin films, the surface composition is the same as the bulk, and core level shifts reflect the inter-metallic interaction between the component metals. Hydrogen absorption is hindered in the PdBi alloys, and at a composition of 70 at.% bismuth, the ??Bi₂Pd bulk alloy phase is identified in XRD. This phase exhibits a maximum in the hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) electrocatalytic activity. The increased activity of the alloy can be understood in terms of the Pd d-band density of states, and a concomitant increase in the binding energy of hydrogen. There is a strong correlation between the HER and HOR activity as a function of composition across the complete range of alloys. The potential of using the ??Bi₂Pd bulk inter-metallic phase at the anode of PEM fuel cells is briefly discussed.     

Electrochemical deposition and characterization of ZnCo alloys and corrosion protection by electrodeposited epoxy coating on ZnCo alloy

ZnCo alloys electrochemically deposited on steel under various deposition conditions were investigated. The influence of deposition current density, temperature and composition of deposition solution on the phase structure and corrosion properties of ZnCo alloys were studied. It was found that ZnCo alloy obtained from chloride solution at 5 A dm⁻² showed the best corrosion properties, so this alloy was chosen for further examination. Epoxy coating was electrodeposited on steel and steel modified by ZnCo alloy using constant voltage method. The effect of ZnCo alloy on the corrosion behavior of the protective system based on epoxy coating is interpreted in terms of electrochemical and transport properties, as well as of thermal stability.     

Preparation of a thick NiAl/Al2O3 coating by embedding method and its corrosion resistance under supercritical water environment

One of the critical issues in the application of supercritical water oxidation technology is to improve the corrosion resistance of reactor materials. Use of Al₂O₃ coating is one of the most promising methods to address this issue. In this study, thick NiAl/Al₂O₃ coatings on Inconel 625 substrates were prepared by a consecutive pack embedding and in-situ thermal oxidation process. The effect of aluminizing and oxidation temperature on phase structure and coating thickness is studied. Results show the diffusion of Al from the exterior to the interior of the alloy matrix to form intermetallic compounds between Al and metal elements in the matrix (Ni, Cr, Mo, etc.). Moreover, the coating thickness can reach above 300 μm at the aluminizing temperature of 950 °C. Increasing the aluminizing temperature above 950 °C will not increase the coating thickness further. After high temperature oxidation subsequently, only phases of NiAl and Al₂O₃ were detected. The formation of Al₂O₃ layer can be ascribed to the surface oxidization of Al. And the NiAl between the alloy substrate and Al₂O₃ coating provides an interfacial layer that can alleviate the crack or exfoliation of ceramic coating due to the mismatching of thermal expand coefficient. The thick NiAl/Al₂O₃ coatings prepared by aluminizing 950 °C and oxidizing at 1100 °C exhibit satisfied corrosion resistance after supercritical water test. This work would provide a significant method to develop advanced ceramics coating for the corrosion resistance of alloys.     

Microstructure and electrochemical characteristics of Mm(Ni,Co,Mn,Al)5Bx (x=0-0.4) hydrogen storage alloys prepared by cast and rapid quenching

Low Co AB₅-type MmNi_3.8Co_0.4Mn_0.6Al_0.2B_x (x=0, 0.1, 0.2, 0.3, 0.4) hydrogen storage alloys were prepared by cast and rapid quenching. The microstructures and electrochemical performances of the as-cast and quenched alloys were analysed and measured. The effects of boron additive and rapid quenching technique on the microstructures and electrochemical properties of as-cast and quenched alloys were investigated comprehensively. The experimental results showed that the microstructure of as-cast MmNi_3.8Co_0.4Mn_0.6Al_0.2B_x (x=0, 0.1, 0.2, 0.3, 0.4) alloys was composed of CaCu₅-type main phase and a small amount of CeCo₄B-type secondary phase. The abundance of the secondary phase increases with the increase of boron context x. The rapid quenching techniques were used in the preparation of the alloys. The amount of secondary phase in the alloys decreased with the increase of quenching rate. Rapid quenching made lattice constants increase slightly. The effects of rapid quenching on the electrochemical performances of the alloys are very significant. The discharge capacity of the alloys decreased obviously and the cycle stability increased dramatically with the increase of quenching rate. Rapid quenching made the activation capability of the alloys lowered. However, the activate performance and high rate discharge capability as well as discharge voltage characteristic of the alloys were modified obviously with the increase of boron content x.