铁酸钴钠米晶体材料的制备

以ＦｅＳＯ４．７Ｈ２Ｏ和ＣｏＳＯ４．７Ｈ２Ｏ为原料,首先制备出晶粒细小的盐渍 化碱式碳酸盐前驱体。在３００－７００℃焙烧１小时后,制备出ＣｏＦ２Ｏ４纳米晶体材料,经ＸＲＤ和ＴＥＭ检测,粒径为１０－４０ｎｍ,粒度均匀。     

以球形α-Ni_(0.8)Co_(0.2)(OH)_2制备锂离子电池正极材料LiNi_(0.8)Co_(0.2)O_2

ＬｉＮｉ０．８Ｃｏ０．２Ｏ２是很有希望取代ＬｉＣｏＯ２的新一代锤离子电池正极材料．采用控制结晶法合成球形 α－Ｎｉ０．８Ｃｏ０．２（ＯＨ）２为前驱体,与 ＬｉＯＨ·Ｈ２Ｏ混合,在７００℃通Ｏ２热处理４ｈ合成锂离子电池正极材料ＬｉＮｉ０．８Ｃｏ０２Ｏ２粉末．Ｘ光衍射分析表明合成的ＬｉＮｉ０．８Ｃｏ０．２Ｏ２粉末结晶良好,具有规整的α－ＮａＦｅＯ２层状结构．扫描电镜分析表明粉末颗粒呈球形,粒径约８μｍ．粉末的流动性好,堆积密度高．充放电测试表明,合成的 ＬｉＮｉ０．８Ｃｏ０．２Ｏ２正极材料具有优良的电化学性能：首次充电比容量为１９７ｍＡｈ·ｇ－１,放电比容量为１７４ｍＡｈ·ｇ－１,１０次充放电循环后保持初始放电比容量的９６．６％．     

铁酸钴纳米晶体材料的制备

以ＦｅＳＯ４·７Ｈ２Ｏ和ＣｏＳＯ４·７Ｈ２Ｏ为原料,首先制备出晶粒细小的盐渍化碱式碳酸盐前驱体。在３００—７００℃焙烧１小时后,制备出ＣｏＦ２Ｏ４纳米晶体材料,经ＸＲＤ和ＴＥＭ检测,粒径为１０—４０ｎｍ,粒度均匀     

流态化CVD制备TiO2—Al2O3复合粒子

本文探讨了流态化ＣＶＤ反应器中Ｔｉ（ＯＣ４Ｈ９）４水解制备ＴｉＯ２－Ａｌ２Ｏ３复合粒子新工艺，借助于ＳＥＭ、ＴＥＭ、ＢＥＴ、ＸＲＦ和ＥＰＭＡ等现代测试手段研究了复合粒子结构和包覆过程特征。结果表明，在流态化ＣＶＤ反应器中Ａｌ２Ｏ３超细颗粒以团聚体形式存在，ＴｉＯ２包覆量随Ｔｉ（ＯＣ４Ｈ９）４进料浓度升高而增加，但反应温度影响不大；在包覆过程中，同时存在成核和成膜，成核包覆使复合粒子比表面积增加，成     

流态化CVD制备TiO_2－Al_2O_3复合粒子

本文探讨了流态化ＣＶＤ反应器中Ｔｉ（ＯＣ４Ｈ９）４水解制备ＴｉＯ２－Ａｌ２Ｏ３复合粒子新工艺，借助于ＳＥＭ、ＴＥＭ、ＢＥＴ、ＸＲＦ和ＥＰＭＡ等现代测试手段研究了复合粒子结构和包覆过程特征．结果表明，在流态化ＣＶＤ反应器中Ａｌ２Ｏ３超细颗粒以团聚体形式存在，ＴｉＯ２包覆量随Ｔｉ（ＯＣ４Ｈ９）４进料浓度升高而增加，但反应温度影响不大；在包覆过程中，同时存在成核和成膜，成核包覆使复合粒子比表面积增加，成膜包覆使复合粒子比表面积减小．     

喷雾干燥法制备LiCoO2超细粉

本文研究了一种新型的制备锂离子电池正极材料的工艺方法通过喷雾干燥法制备出 Ｌｉ Ｃｏ Ｏ２超细粉试验中, 进行了混合粉体的 Ｄ Ｔ Ａ Ｔ Ｇ Ａ 分析; Ｘ Ｒ Ｄ 谱分析显示, 所得 Ｌｉ Ｃｏ Ｏ２ 为具有α Ｎａ Ｆｅ Ｏ２ 层状结构的 Ｈ Ｔ Ｌｉ Ｃｏ Ｏ２ ; 从 Ｓ Ｅ Ｍ 照片可见, Ｌｉ Ｃｏ Ｏ２ 粉末元素分布均匀, 粒径为几百纳米;电化学性能测试结果表明, 其充电容量为１４８ｍ Ａ·ｈｇ , 放电容量为１３５ｍ Ａ·ｈｇ, 具有优良的电化学性能     

气相反应法合成超细粉末过程中的r~＊叶和晶型的研究

本文以ＳｉＣｌ４－ＮＨ３、ＳｉＣｌ４－Ｏ２、ＳｉＣｌ４－Ｎ２－Ｈ２、ＴｉＣｌ４－ＮＨ３－Ｈ２、ＴｉＣｌ４－Ｎ２－Ｈ２、ＴｉＣｌ４－Ｏ２、ＡｌＣｌ３－Ｏ２等为体系，运用均匀成核理论，研究了平衡常数Ｋｐ、过饱和比Ｓ及临界核半径，ｒ＊等因素对气相反应法中超细粉末的形成及粉末结构状态的影响．结果表明，当２ｒ＊大于某物质的晶格常数时，用气相反应法得到的该物质的超细粉末一般为晶体粉末，反之则得到无定形粉末．     

Al2O3／SiC纳米复合陶瓷与配副在熔融锌中的磨蚀

本文将Ａｌ２Ｏ３／ＳｉＣ纳米复合陶瓷分别与Ｃｒ２５Ｎｉ５合金,Ｃｏ－Ｃｒ－Ｗ合金及烧结Ｗ环三种配制材料在４６５℃的熔融锌液中进行环－块腐蚀磨损实验。结果表明耐锌腐蚀是各种材料耐磨的前提。Ｗ（环）与Ａｌ２Ｏ３／ＳｉＣ纳米复合陶瓷（块）是最佳的摩擦副。     

PMN-PT弛豫铁电粉体的溶胶-凝胶法制备及其性质

以无机盐或氧化物Ｎｂ_２Ｏ_５、ＭｇＯ、ＴｉＣｌ_４和Ｐｂ（ＡＣ）_２、３Ｈ_２Ｏ为原材料,柠檬酸和ＥＤＴＡ为复合螫合剂,乙二醇为溶剂,分别制备Ｎｂ、Ｍｇ－Ｎｂ、Ｔｉ和Ｐｂ的有机化合物前驱液,采用溶胶－凝胶工艺制备ＰＭＮ－ＰＴ弛豫铁电陶瓷粉体及其烧结体．讨论了制备工艺和螯合剂等对金属有机化合物溶液的性质、材料物相形成和介电性能的影响．     

氧缺位铁酸盐MFe2O4—δ的制备条件研究

使用ＸＲＤ、Ｍｏｓｓｂａｕｅｒ谱结合化学分析考查了５７３Ｋ下还原时间对空气氧化碱性悬浮液合成的铁酸盐ＭＦｅ２Ｏ４＋δ（δ≥０）的物相、晶格常数及化学组成的影响，得出了制备氧缺位铁酸盐ＭＦｅ２Ｏ４－δ（δ＞０）的最佳条件。结果表明，在５７３Ｋ下制备ＭＦｅ２Ｏ４－δ的最佳还原时间按Ｆｅ、Ｃｏ、Ｍｎ、Ｎｉ顺序分别为１０ｈ、３ｈ、４０ｍｉｎ和３０ｍｉｎ，氧缺位程度及晶格常数在最佳还原时间之前随还原时间增长而增大，在接近最佳还原时间时达到极大值。ＭＦｅ２Ｏ４－δ的极大值δ按Ｆｅ、Ｃｏ、Ｍｎ、Ｎｉ顺序减小，超过最佳还原时间ＭＦｅ２Ｏ４－δ将分解为α－Ｆｅ（Ｍ＝Ｆｅ）或ＭＯ－ＦｅＯ（Ｍ＝Ｃｏ、Ｍｎ、Ｎｉ）。     

Recycling process of WC-Co cermets by hydrothermal treatment

Hydrothermal extraction process of Co binder phase from WC-Co cermet was investigated in order to establish a novel recycling system of WC-Co cermet scraps. When the cermet chips were hydrothermal-treated in hydrochloric acid above 110^∘C, Co binding phase was efficiently extracted and the cermet chips were disintegrated into relatively large fragments. After hydrothermal treatment, WC sintered body become very brittle and pulverized easily by ball milling and the mean particle size of thus obtained WC particle became similar to that of virginal WC particle. The recycled WC powder was a little easier to undergo oxidation than the virginal WC powder, so that the mechanical properties of recycled WC-Co cermets were degraded. However, the degradation of mechanical properties was prevented only by drying the WC powder more carefully. This hydrothermal process will be one of the recycling systems for WC-Co cermets.     

Research on Ultrafine Tungsten Carbide-Cobalt (WC-Co) Cemented Carbide Rods of Miniature Drills for Highly Integrated Printed Circuit Board (PCB)

Nanocrystalline tungsten carbide-cobalt (WC-Co) composite powders produced through spray thermal decomposition-continuous reduction and carburization technology were used to prepare φ3.25 mm×38 mm ultrafine tungsten carbide-cobalt (WC-Co) cemented carbide rods through vacuum sintering plus sinterhip technology. The microstructure, Vickers hardness, density and Rockwell A hardness (HRA), transverse rupture strength (TRS), saturated magnetization and coercivity force were tested. The results show that the average grain size of the sintering body prepared through vacuum sintering plus sinterhip technology was 430 nm; transverse rupture strength (TRS) was 3850 MPa; Vickers hardness was 1890 and Rockwell A hardness of sintering body was 93. High strength and high hardness ultrafine WC-Co cemented carbide rods used to manufacture printed circuit board (PCB) drills were obtained.     

Synthesis of Nanophase WC Powder by Displacement Reaction

ABSTRACT

Conventional thermochemical processing of nanophase WC powder involves hydrogen reduction of a tungsten precursor compound to form high surface area α-W. followed by gas phase carburization to develop WC. This two-step process inevitably leads to some coarsening of the nanophase WC powder product. Recently, we have developed a new method, called “displacement reaction processing”, in which the two steps (reduction and carburization ) are combined into a single step, leading to a much finer nanostruciure for the product WC powder. The one-step process is particularly favored when H₂ reduction of the precursor compound results in the formation of an amorphous oxygen-rich intermediate. The resulting nanophase WC has a particle size < 10 nm. In this talk, the procedures that must be followed to promote one-step WC powder processing, starting from different tungsten-based precursors, will be described, and the mechanisms discussed.     

Fabrication of NiO/YSZ anode material for SOFC via mixed NiO precursors

NiO/YSZ anode material with 45 wt.% NiO for SOFC was synthesized by surface-modification of YSZ powder with mixed nickel oxide precursors. YSZ was treated with acidic nickel nitrate and then followed by basic nickel carbonate. Such prepared NiO/YSZ precursor showed nano-size homogeneous mixture upon calcination at 800 °C. The mixture was ground and subjected to calcination at 1200 °C to give rise to agglomerate-free NiO/YSZ composite powder with particle size of ∼ 0.4–0.7 μm. The composite powder was analyzed by XRD, zetapotential measurements, and SEM. The composite powder produced the Ni/YSZ cermet of homogeneous microstructure with a rigid YSZ skeleton, porosity of 33%, and an electrical conductivity of ∼ 430 S/cm at 800–1000 °C, which is much higher than that (∼ 180 S/cm) prepared by a conventional mixed oxide process.     

Observation of Co nanoparticle dispersions in WC nanograins in WC-Co cermets consolidated from chemically synthesized powders

High resolution, and analytical electron microscopy has been used to analyze morphological features in consolidated specimens of nanostructured tungsten carbide-cobalt cermet materials prepared from chemically synthesized nanostructured WC-Co powder. The investigation includes studying materials produced by consolidation (i) above, and (ii) below the eutectic temperature by thermo-mechanical working. In the case of liquidphase sintered material, the study includes examining the influence of a vanadium carbide additive on morphological features, as well as its effect in inhibiting grain growth. Electron microscope examination of all consolidated materials reveals a dispersion of nanoprecipitates within the WC nanograins of the WC-Co cermet. Micro-diffraction and analytical studies show that these nanoprecipitates are f.c.c. cobalt. This novel discovery is consistent with the concept that the nanoprecipitates nucleate from cobalt retained within the WC nanograins, which is a consequence of the intimate intermixing of tungsten and cobalt in the original chemical synthesis process.     

Synthesis and Characterizations of Nanocrystalline WC-Co Composite Powders by a Unique Ball Milling Process

In order to explore the high efficiency of fabricating nanocrystalline WC-Co composite powders, this paper presented a unique high energy ball milling process with variable rotation rate and repeatious circulation, by which nanocrystalline WC-10Co-0.8VC-0.2Cr3C2 (wt pct) composite powders with mean grain size of 25 nm were prepared in 32 min, and the quantity of the powders for a batch was as much as 800 grams. The as-prepared powders were analyzed and characterized by chemical analysis, X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential thermal analysis (DTA). The results show that high energy ball milling with variable rotation rates and repeatious circulation could be used to produce nanocrystalline WC-Co powder composites with high efficiency. The compositions of the powders meet its specifications with low impurity content. The mean grain size decreases, lattice distortion and system energy increase with increasing the milling time. The morphology of nanocrystalline WC     

反应等离子喷涂Fe-Al2O3-FeAl2O4复合涂层的反应机理研究

金属/陶瓷复合涂层具有金属的韧性和陶瓷的高强度、高硬度等优点,利用反应等离子喷涂技术将Fe2O3/Al复合粉制备成金属/陶瓷复合涂层,以X射线衍射(XRD)、扫描电镜(SEM)、能谱仪(EDS)等分析技术研究了该复合涂层的反应机理和涂层性能.结果表明:涂层具有以层状的FeAl2O4、Al2O3为骨架,球形的Fe及部分FeAl为弥散相的复合组织;复合粉体反应形成涂层的过程是分步进行的,而且在熔滴到达基体后部分反应仍继续进行;一定程度上,由于反应过程受到Al元素的扩散限制,同时等离子喷涂的冷却速度较高,使得涂层中主要含有FeAl2O4及少量的FeO.     

Electron-beam Treatment of Tungsten-free TiC/NiCr Cermet Ⅰ:Influence of Subsurface Layer Microstructure on Resistance to Wear during Cutting of Metals

An experimental investigation were performed on the effect of the impulse electron-beam irradiation upon microstruc-ture of the surface layer and on wear resistance of a cutting tool for sintered TiC/NiCr cermet. The results showed that the surface electron-beam treatment of the TiC/NiCr cermet is an efficient method for investigating the mi-crostructure and phase composition in the surface layer of the powder composite and there are optimal regimes of electron-beam treatment, which ensure a substantial increase in the resistance of the cermet to wear during cutting of metals.     

Microstructure and Properties of WC-Co/NiCrBSi Brazing Coating

1.IntroductionModernengineeringapplicati0nsshowthatagreatamount0fdamagethatmaterialssh0wisrelatedt0surfacewear.Byusingcoatingtechniques,itisp0ssi-blet0pr0tectagainstwear.Theadvantages0fcoat-ingarealongerservicelifeperf0rmanceresultingfr0moptimizedmaterialcombinationsandaconsequentre-ductionofcost.Thesurfacepr0pertiesofstructuralcomp0nentsin0ilandmineindustrieshavesostr0nginflllence0ntheirbehavi0rthatseveralsurfacemodi-ficationshavebeenusedinthosepr0fessions,suchasthermalspraying,surface0verlay…     

Cemented carbide reinforced nickel-based alloy coating by laser cladding and the wear characteristics

Composite coatings composed of metal matrix and ceramic particles have received particular attention in surface engineering. In this paper nickel base alloy powder and WC-Co cemented carbide particles have been chosen to manufacture composite coatings by use of kW CO₂ laser. Laser processing parameters including output power and scanning speed have been optimized. X-ray diffractor, optical and electron microscopes and energy dispersion spectra have been applied to investigate the phase constituents and microstructures of the coating. Block-on-ring dry sliding wear test and rubber wheel slurry erosive abrasion wear test have been conducted to study the wear properties of the composite coating as well as the reinforcing effect of WC-Co particles. A 50–100 mm wide ring appeared along the particle side of the particle-matrix boundary, showing superior wear and corrosion resistance, higher than even the original central part of the WC-Co particle. The mechanism of its formation has been probed.