相转移分离法制备氧化钇稳定的氧化锆超细粉末

相转移分离法是1种新颖的陶瓷粉末制备方法,能迅速有效地从溶液中分离出高度亲水的氢氧化物沉淀,从而达到液-固分离的目的。本研究首次用该方法制备了8mol%氧化钇稳定的氧化锆(8YSZ)超细粉末。合成的8YSZ粉末具有赝立方结构,平均粒径在20nm～30nm左右。粉末中Na和Cl的含量分别为7.05×10-6和1.414×10-4。工艺中的石油醚可以回收,回收率为80%。可以认为,相转移分离法是1种有广阔应用前景的超细陶瓷粉末制备方法。     

超细碳化钨钴复合粉末的合成

报导了超细碳化钨钴复合粉末的合成方法．作者用一种新的，可通用的，分步热解—热化学转化工艺成功地合成了超细碳化钨钴复合粉末，并用扫描电子显微镜，X射线衍射，透射电子显微镜和差热分析对超细碳化钨钴复合粉末及其中间产物进行了测试分析．结果表明，这种方法合成的碳化钨钴复合粉末具有良好的综合性能及超细的平均晶粒度（＜200nm）．     

甘氨酸-硝酸盐法制备NiO-Sm掺杂CeO2复合阳极粉末研究

采用甘氨酸-硝酸盐燃烧法合成了中温固体氧化物燃料电池NiO-SDC复合阳极粉末。通过XRD和扫描电子显微镜对不同甘氨酸／金属离子摩尔比合成的复合粉末的结构和形貌进行了研究。XRD结果表明，直接燃烧合成的复合粉末除了NiO和CeO2的衍射峰外，还有Ni2O3衍射峰存在，粉末经900℃煅烧2h后Ni2O3峰消失，表明形成了NiO-SDC复合阳极粉末。氢气条件下的热重分析表明，复合粉末中NiO和SDC两相比例与溶液组分配比基本一致。制备的不同NiO含量薄膜阳极的电解质支撑单电池性能测试结果表明，阳极为60％NiO-SDC的单电池具有最高的开路电压。     

采用机械化学法合成ZrO_2纳米晶粉末

澳大利亚来斯顿大学的先进矿物和材料加工专门研究中心报道了一种合成Y2O3稳定ZrO2纳米晶粉末的机械化学法。机械化学法已扩展为一种通过低温固态化学反应合成材料的方法。在该工艺过程中，研究介质之间相互碰撞使得粉末频繁断裂与焊接，从而保持了高的反应界面面积。因而，在正常情况下由于扩散速率低而被抑制的固态化学反应能在不需要外部提供能量的情况下发生。适当设计的机械化学反应可用于合成纳米晶粉末。合成的超细颗粒分散于可熔盐的基体中。用适当的溶剂选择性地洗去基体相可获得超细粉末。这种方法技术简单，用途广泛。已经成功…     

高频等离子法制取超细氮化钛反应动力学研究SCIEI

本文研究了等离子法合成超细氮化钛反应动力学,建立了TiCl_4-NH_3-H_2-N_2系统在高频等离子反应器中气相合成超细TiN粉末的反应动力学模型,对影响反应速度的主要因素进行了分析,为控制TiN产品的质量及对等离子反应器的优化设计提供了理论依据。     

亚微米级单分散超细氧化铝制备工艺研究

本文综合使用中和法和改良拜耳法,以价格低廉的铝酸钠溶液和工业硫酸铝为基本原料,研究成本低廉、易于规模化生产的亚微米级超细α-Al_2O_3生产工艺。该工艺首先将铝酸钠和硫酸铝溶液进行中和反应,制备活性种子,而后将该种子加入铝酸钠溶液种分制备前驱体,前驱体再经热处理后获得超细α-Al_2O_3。结果表明,通过对反应速度、浓度和反应体系p H的合理控制,可以合成出纳米级、无定形超细种子;通过对种子添加量的合理控制,可以合成出粒径小于1μm、粒径分布窄、分散性能优良的超细氧化铝粉体。     

合成超细碳化钨钴复合粉末的一种新方法

简要介绍了采用钨钴液相复合──喷雾干燥──流态化热化学转化工艺（SCP）,合成超细碳化钨钴复合粉末的新方法,并用扫描电子显微镜（SEM）、X─射线衍射（XRD）、红外光谱（IR）和热重（TGA）、差热（DTA）分析对超细钨钴复合粉末及其中间产物进行了测试分析,结果表明,这种方法合成的碳化钨钴粉末具有组成分子水平的均匀及超细的平均晶粒（＜200um）。     

WC-Co复合粉末的原位合成及于硬质合金涂层制备中的应用

目的为解决超细/纳米WC-Co热喷涂时易于脱碳等瓶颈问题,制备具有高的硬度、断裂韧性、耐磨性和表面质量等优异综合性能的超细及纳米结构硬质合金涂层,并推广其在工业领域中的应用。方法以原位合成技术批量制备的超细/纳米WC-Co复合粉末为原料,利用团聚造粒技术制备得到具有高球形度和致密性,并保持原有超细/纳米结构的喷涂喂料粉末,利用超音速火焰喷涂工艺制备低脱碳、高致密的超细结构WC基涂层。结果降低喂料粉末孔隙度可有效减少涂层中W2C等脱碳相的含量,在优化工艺下制备的超细结构WC基涂层的硬度达到1450HV0.3以上,韧性相对于常规微米结构涂层提高40%以上,在两种载荷和磨料条件下均表现出更高的耐磨性。结论利用原位反应技术批量合成的超细/纳米WC-Co复合粉制备的硬质合金涂层具有优良的综合性能,可应用于对涂层的硬度、耐磨性、强韧性配合和表面质量有较高要求的工况。     

纳米Ni-Co合金粉末的溶液还原法制备与表征

研究了溶液还原法制备超细Ni-Co合金粉末的方法,以NiSO4和CoSO4的溶液为原料,N2H4·H2O为还原剂,NaOH调节溶液的pH值,控制反应条件为NiSO4,CoSO4的总浓度为1.0mol·L（－1）,N2H4·H2O／Ni,Co总量为2.0,NaOH／Ni,Co总量为1.0,反应温度为90℃,将得到的沉淀物洗涤、干燥,获得了平均粒径为60nm的球形超细Ni-Co合金粉末。并对制备的粉末采用TEM,XRD,EDAX和IAS法进行了表征。结果表明,本法制备的粉末具有粒度小、分布均匀、纯度高等特点。     

超细WC—10Co硬质合金的显微结构与机械性能

本文对超细WC-10wt％Co-X硬质合金的机械性能进行了研究：通过喷雾干燥，用舍AMT和硝酸钴溶液来制取超细原始粉末，再用机械一化学工艺，将原始粉末还原和碳化成WC／Co粉末：直径大约为100nm的WC粉末与粘结剂Co均匀地混合，在n-已烷和球料比为5：1的条件下湿磨24小时，过后再干燥24小时，并在Imtorr压力下和1375℃二的温度下进行烧结：为了比较超细硬质合金的显微结构与机械性能，将直径为0．57μm～4μm的WC粉末与Co粉末进行混合，随后在1mtorr压力下和1375℃二的温度下烧结：添加不同数量的TaC、Cr3C2、和VC晶粒长大抑制剂到WC-10wt％Co超细硬质合金中，发现烧结后超细硬质合金中的Co相在WC晶粒的边缘快速产生：Hall-Petch类型关系说明WC—10wt％Co硬质合金的硬度是随着WC晶粒度的下降而增加，而抗弯强度则取决于Co粘结相中的溶解度。     

Self-propagating high-temperature synthesis of La(Sr)Ga(Mg)O3−δ for electrolyte of solid oxide fuel cells

This paper describes self-propagating high-temperature synthesis (SHS) of an electrolyte for solid oxide fuel (SOFC), in comparison to a conventional solid-state reaction method (SRM). Doped-lanthanum gallate: La_0.9Sr_0.1Ga_0.8Mg_0.2O_3−δ (LSGM9182) and LSGM9173 as the SOFC electrolyte, was prepared by the SHS and sintered at different temperatures, for measuring the electrical conductivity of the sintered LSGM and the power generating performance at 1073 K, in comparison to the SRM. In the SHS, the LSGM powders with smaller size were obtained and easily sintered at the 100 K-lower temperature, 1673 K, than in the SRM. Most significantly, the electrical conductivity of the sintered LSGM9182 was as high as 0.11 S cm⁻¹ and its maximum power density was a value of 245 mW cm⁻² in the cell configuration of Ni/LSGM9182 (0.501 mm in thickness)/Sm_0.5Sr_0.5CoO₃. The conclusion was that the proposed SHS-sintering method with many benefits of minimizing the energy requirement and the processing time in the production, easing temperature restriction for the sintering, and improving the electrolyte performance up to a conventional level is practicable for producing the LSGM-electrolyte of SOFC at an intermediate-temperature application.     

Characterization of in situ synthesized TiC particle reinforced Fe-based composite coatings produced by multi-pass overlapping GTAW melting process

In this paper, in situ synthesized TiC particles reinforced Fe-based surface composite coatings by multi-pass overlapping gas tungsten arc welding (GTAW) melting process employing a proper amount of graphite and ferrotitanium (FeTi) on AISI 1020 steel substrate was produced. The microstructure and wear properties of the composite coatings were investigated by means of an electron microprobe microanalysis (EPMA), X-ray diffractometer and wear tester. The results showed that the multi-pass overlapping GTAW melting surface composite coatings can be obtained under suitable welding parameters, and no crack and porosity are found in the tracks. The X-ray and EPMA results confirm that TiC particles can be formed via reaction of FeTi and graphite during multi-pass overlapping GTAW melting process. TiC particles present cubic and dendrite shape in the non-overlapping zone. It is found that there occurred TiC particles coarsening at the overlap regions, which can lead to detrimental effects on the hardness and wear performance. Composite coatings give a high hardness and excellent wear resistance; and the wear friction coefficient of the coating is less than that of the 1020 steel. As a result, multi-pass overlapping GTAW melting process can be used effectively for producing surface composite coatings with a pre-placed powder to improve wear resistance of the AISI 1020 steel.     

Microstructure and electrical properties of Ti-modified (Na_(0.5)K_(0.5))(Ti_xNb_(1-x))O_3 lead-free piezoelectric ceramics

Ti-Modified (Na0.5K0.5)(TixNb1-x)O3 (NKNT) piezoelectric ceramics were fabricated by double-layer buried powder process at 1020°C for 2 h. The microstructures,and piezoelectric and dielectric properties of the lead-free NKNT ceramics were investigated. X-ray diffraction re-sults indicated that Ti4+ had diffused into the (Na0.5K0.5)NbO3 lattices to form a solid solution with a perovskite structure. The introducing of Ti into the (Na0.5K0.5)NbO3 solid solution effectively reduced the sintering temperature and...     

Intermediate temperature solid oxide fuel cell based on fully integrated plasma-sprayed components

This work addresses the fabrication of membrane-type solid oxide fuel cells (SOFCs) operating at medium temperatures, where all components are fabricated by plasma spray technology, and the evaluation of the performance of the SOFC single unit in a temperature range of 500 to 800 °C. Single cells composed of LaSrMgO₃ cathodes, LaSrGaMgO₃ (LSGM) electrolytes, and Ni/yttria-stabilized zirconia anodes were fabricated in successive atmospheric plasma-spraying processes. Plasma-spraying processes have been optimized and tailored to each layer to achieve highly porous cathode and anode layers as well as high-density electrolyte layers. A major effort has been devoted to the production of the LSGM electrolyte that has a high density and is free of cracks. Electrochemical impedance spectroscopy was used to investigate the conductivity of the electrode layers, and particularly the resistance of the electrolyte layer. It revealed that the heat treatment had a great influence on the specific conductivity of the sprayed electrolyte layers and that the specific conductivity of the heat-treated layers was dramatically increased to the same magnitude as is typical for sintered LSGM pellets. The experimental results have demonstrated that the plasma-spraying process has a great potential for the integrated fabrication of medium-temperature SOFC units. The original version of this article was published as part of the ASM Proceedings, Thermal Spray 2003: Advancing the Science and Applying the Technology, International Thermal Spray Conference (Orlando, FL), May 5–8, 2003, Basil R. Marple and Christian Moreau, Ed., ASM International, 2003.     

热处理对粉末冶金Inconel 718高温合金组织及性能的影响

以超高转速等离子旋转电极法(SS-PREP法)制备的高球形度Inconel 718高温合金粉末为原料,采用热等静压(HIP)工艺制备了Inconel 718粉末高温合金,重点研究了热处理制度对合金组织和力学性能的影响。实验结果表明:采用SS-PREP法制得的Inconel 718高温合金粉末粒度分布均匀,球形度良好,具有优异的HIP工艺性能;随着固溶温度的提高,合金晶界逐渐变浅,说明晶界析出相数量逐渐减少。时效热处理后,沿晶界析出大量针状δ相,同时还有少量MC碳化物相。在1210℃、120MPa条件下保温保压4h的HIP工艺下,经1020℃固溶热处理后,合金室温抗拉强度可达1404MPa;经980℃固溶处理后,合金在650℃的高温抗拉强度为1153MPa,固溶处理温度为980℃的合金综合性能较好。     

IT-SOFC复合阳极材料CDC-LSCMCo的制备及性能

采用甘氨酸-硝酸盐法(GNP法)一次性合成固体氧化物燃料电池复合阳极材料Ce0.8Ca0.2O2-La0.7Sr0.3Cr0.5Mn0.5-xCoxO3-δ(CDC-LSCMCo)。XRD、SEM和EDS分析结果表明:1350℃下烧结5h能够得到单一萤石-钙钛矿结构且粒度较小(1μm左右)的复合阳极粉体。电导率的测试研究发现,温度大于750℃时,电导率随Co含量的增加而增大。800℃时,CDC-LSCMCo0.15分别在空气与氢气气氛下的电导率分别为10.5和0.7S·cm-1。SEM和XRD分析表明:CDC-LSCMCo与La0.9Sr0.1Ga0.8Mg0.2O3-δ电解质材料有很好的热与化学相容性,是一种应用前景良好的IT-SOFC阳极材料。     

Effect of the processing route on the oxidation behaviour of a Ni3Al powder metallurgy alloy

This work deals with the oxidation behaviour of a powder metallurgy (PM) Ni₃Al alloy synthesised using rapidly solidified powder particles, which were milled for 20 h before consolidation by hot isostatic pressing. Oxidation kinetics was evaluated in the temperature range of 535 to 1020°C, with special emphasis at 635°C for which tests were performed up to 1000 h. Oxidation rate was lower than that showed by the material made from non-milled powder particles, irrespective of the oxidation temperature and exposure time. This better oxidation behaviour is associated to the smaller average grain size of the substrate induced during the milling stage, which favoured formation of a thin alumina layer.     

Bond Strength of Multicomponent White Cast Iron Coatings Applied by HVOF Thermal Spray Process

Multicomponent white cast iron is a new alloy that belongs to system Fe-C-Cr-W-Mo-V, and because of its excellent wear resistance it is used in the manufacture of hot rolling mills rolls. To date, this alloy has been processed by casting, powder metallurgy, and spray forming. The high-velocity oxyfuel process is now also considered for the manufacture of components with this alloy. The effects of substrate, preheating temperature, and coating thickness on bond strength of coatings have been determined. Substrates of AISI 1020 steel and of cast iron with preheating of 150 °C and at room temperature were used to apply coatings with 200 and 400 μm nominal thickness. The bond strength of coatings was measured with the pull-off test method and the failure mode by scanning electron microscopic analysis. Coatings with thickness of 200 μm and applied on substrates of AISI 1020 steel with preheating presented bond strength of 87 ± 4 MPa.     

Effect of Fe-based pre-alloyed powder on the microstructure and holding strength of impregnated diamond bit matrix

An iron-rich pre-alloyed powder was selected out, and the pre-alloying degree of matrix materials and the sintering temperature were considered to investigate the effect of the Fe-based pre-alloyed powder on the microstructure and holding strength of impregnated diamond bit matrix. And relative density and bending strength of the specimens were measured, and then the resulting fracture surfaces were analyzed using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results showed that the relative density, bending strength and plasticity of matrix materials are increased with the sintering temperature and the pre-alloying degree. The influence of the pre-alloying degree on them is more significant than that of the sintering temperature within the experimental parameters. Besides, Fe-based matrices have thermal corrosion effect on diamonds at high temperature sintering process. And the rate of diamond graphitization has a greatly increase with the sintering temperature changes from 900 °C to 1020 °C and the holding strength decreases. A low pre-alloying degree accelerates the rate of diamond graphitization. But an adequate pre-alloying degree of Fe-based matrix materials is conducive to improve the wettability of the matrix to diamonds, alleviate the diamond graphitization, reduce the diamonds' thermal damage and improve the holding strength. Besides, it can also greatly reduce the sintering temperature and broaden the sintering temperature range. In a word, it is feasible and reasonable that Fe-based pre-alloyed powders replace Fe elemental powders to fabricate impregnated diamond bits. And it has a good economic value and broad application prospect.     

湿化学法制备锶镁掺杂镓酸镧基固体电解质材料的研究进展

本文综述了国内外学者采用湿化学法制备锶镁掺杂的镓酸镧基固体电解质（LSGM）的研究现状。阐述了每种制备方法的制备过程和主要特点，并同传统固相反应法进行了比较。最后对LSGM材料进一步研究的方向进行了展望。