流延成型制备8YSZ电解质薄片及其性能研究

探索了以YSZ纳米粉体为原料,采用流延成型的方法制备YSZ电解质薄片的工艺过程,研究了YSZ纳米粉体及流延后坯体的性能,以及通过实验获得的瓷体性能.粉体粒度分布窄,在0.1~0.3μm之间,中位径为0.157μm.坯体在968.9℃开始有明显收缩,在1 279.9℃收缩最快,而在1400℃后,收缩值基本稳定于20%.坯体的致密度良好,相对密度为64.1%,通过烧结得到的瓷体的相对密度可达97.8%,晶粒细密均匀,大小为1-4 μm,晶界明显.YSZ薄片随温度的升高表现出良好的电性能,在900℃时的电导率达0.106 S/cm.     

流延成形-熔渗烧结制备WCu20合金薄板

采用热化学镀技术制备的铜含量为11%(质量分数)、平均粒度为5~10μm的铜包钨复合粉末为原料,经过胶体的流延成形、500℃脱胶、1 200℃预烧、600 MPa预压和1 300℃熔渗烧结,制备出厚度为0.2 mm、相对密度达98.8%的WCu20合金薄板;其组织呈现Cu相均匀填充在W颗粒周围的网络状分布,电导率达到36%IACS、热导率达到210 W/(m·K)、硬度达到280 HV,均高于相应的国家标准。WCu20合金板材的断裂方式由铜相的韧性断裂和钨相的穿晶断裂组成,包覆铜有利于合金韧性的提高。     

撞击流反应制备钇稳定氧化锆超细粉体

以氧氯化锆和硝酸钇及碳酸氢铵为原料,PEG4000为分散剂,在撞击流反应器中制备钇稳定氧化锆前驱体,焙烧后得到钇稳定氧化锆(YSZ)粉体,考察PEG4000用量、搅拌速率、反应时间和焙烧时间对粉体粒径的影响,并对粉体进行表征。结果表明,优化工艺条件为:PEG4000用量1.4g/L,转速1 000r/min,反应时间65min,前驱粉体在1 460℃焙烧120min,可制得球形、粒度分布均匀、表观直径小于0.5μm的YSZ超细粉体。     

金属薄膜的流延工艺研究

流延成形方法应用于金属薄膜的生产中,由于金属粉末自身比重大以及流延工艺的制备过程复杂,金属薄膜易变形开裂。实验研究了金属流延浆料中各添加剂含量对金属薄膜成形过程和烧结后性能的影响。结果表明：粘结剂含量与粘度对金属薄膜性能起决定性影响,加入10%含量的造孔剂,有效控制了颗粒团聚现象,膜层孔径分布集中,气体透过率提升。实验验证了固含量对流延坯片均匀性的影响;固含量过低,易造成膜层表面开裂,厚度不均匀,烧结后大孔缺陷多,强度差;而固含量过高,会导致膜层气体透过率下降,同时,膜层的柔韧性也会降低。造孔剂可以显著改善膜层表面团聚现象,提高颗粒之间的结合力。     

无压烧结SiC陶瓷研究进展

高硬度、高强度、耐腐蚀、耐磨损和高弹性模量等特性使SiC陶瓷成为航空航天、电力电子和机械工业等领域不可或缺的材料。然而SiC陶瓷超高的合成温度和难以烧结致密的特性限制了它的生产。近年来随着SiC陶瓷烧结机理的深入研究及添加剂的多样化,采用无压烧结工艺制备高性能SiC陶瓷材料已逐渐成为最常用的方法。本文主要阐述了近年来无压烧结SiC工艺添加剂的研究进展,综述了添加剂及其用量、烧结温度和时间对无压烧结SiC陶瓷性能的影响。     

烧结过程物质流和能量流分析

采用物质流和能量流分析方法,提出了铁矿粉烧结过程物质流分析的核心问题,对铁素流、碳素流和硫素流的物理化学状态变化、耗散过程及其影响因素等进行了分析。研究表明:烧结工序铁素流变化主要是矿物形态、结构和冶金性能等的转化;固体燃料是碳素流输入的主要形式,而CO2则是碳素流输出的主要形式;烧结过程具有脱硫功能,是气化脱硫过程,烟气中SO2排放是硫素流输出的主要形式,应注意,烧结工序是钢铁制造流程主要的SO2排放源。     

烧结过程、球团过程的能量流和优化选择

烧结和球团过程的节能是钢铁生产节能的一个重要组成部分。本文从生产实践和我国的现状出发,对烧结和球团过程的能量流进行了分析,并初步根据火用的理论,对烧结和球团过程如何提高火用效率,提出了一些节能的措施和方法。     

三元流技术在烧结主抽风机的实践与应用

通过在烧结主抽风机的叶轮上创新应用三元流技术,改造叶轮叶片结构以适应流体的真实流态,达到风机运行效率的提高,节能效果显著。     

采用天然斜锆石微波烧结制备部分稳定氧化锆陶瓷

以选矿所得的天然斜锆石为原料,通过添加一定量的CaO稳定剂,经微波烧结直接制成Ca增韧部分稳定氧化锆陶瓷。微波设备采用的是自行研制的多模腔微波烧结装置,该装置频率为2．45GHz,最大功率为3kW。实验发现,物料在多模腔中经微波加热至约1300℃保温80min得到部分稳定氧化锆陶瓷,其密度可达到理论密度的92．97％,抗弯强度达138．271MPa。     

气动薄膜调节阀的选择及其在我厂铅烧结混合料湿度控制中的应用

文章较详细地阐述了如何针对不同的工艺条件，对动薄膜调节阀的结构型式、流量特性、口径、开闭形式进行正确选择并且简要介绍了气动薄膜调节在我厂铅烧结混合湿度控制中的应用。     

Microstructure and Mechanical Properties of Yttria-Stabilized Zirconia Coatings Produced by Eletrophoretic Deposition and Microwave Sintering

Y₂O₃-stabilized zirconia coatings were deposited on superalloy K17 substrates at room temperature by the eletrophoretic deposition technique followed by two different sintering methods. Scanning electron microscopy, X-ray diffraction (XRD), and nanoindentation techniques were employed to characterize morphological, structural, and mechanical properties of the coatings. Finer and more uniform microstructures were observed in the microwave sintered coatings. For the conventionally sintered coatings, the monoclinic phase was observed. The microwave sintered coatings of Y₂O₃-stabilized zirconia contain mainly cubic/tetragonal phases with some metastable phase present. In comparison with the hardness of 3.1 GPa and elastic modulus of 83.5 GPa for conventional sintered coating, the hardness and elastic modulus for microwave sintered coating rapidly increased to 4.3 and 172.7 GPa, respectively. Such coatings have potential in being used as thermal barrier coatings (TBCs) on superalloy substrates.     

Mushroom-shaped Morphology Formed in Thin Films of Cylinder-forming Block Copolymer

The morphology of the film of polystyrene-block-poly(methyl methacrylate)(PS-b-PMMA) block copolymer having polystyrene(PS) cylinder forming composition spin-coated on a neutral brush modified silicon substrate has been investigated in this report. A mushroom-shaped morphology formed in the film with one period to two periods(L0-2L0) in thickness, which was spin-coated under a low humidity condition(RH ca. 13%) and then thermally annealed at an extreme high temperature(230℃). The results suggest that the spin-coating condition together with the confinement conditions plays a crucial role in the interesting morphology formation.     

薄板铸机开浇冷齿形成的分析与解决

本钢炼钢厂薄板坯连铸机在开浇初期,特别是在低碳钢的生产时,结晶器内几乎每个浇次开浇时都会产生冷齿,由于薄板坯铸机拉速高,冷齿现象极易产生漏钢的事故,并产生7m左右的废坯,增加了生产成本。因此主要对能够引起冷齿的生产和设备各种相关的因素进行分析,并通过生产实践的方法找出最佳的解决办法。     

Mg粉和Zn粉烧结形成金属间化合物的研究

采用粉末烧结的方法制备Mg-Zn烧结体,利用光学和电子显微镜观察了Mg粉和Zn粉扩散反应区域的形貌,X射线衍射和能谱技术分析了该扩散反应区域的相组成;依据TFDC电子理论对扩散反应区域中金属间化合物的形成机制进行了讨论.研究发现,Mg粉和Zn粉在200 ℃,30 h的烧结过程中,Zn原子不断扩散进入到Mg晶体中,在Mg粉和Zn粉颗粒界面处,先后依次形成MgZn,MgZn2和Mg7Zn3 3种金属间化合物.     

薄板坯及细小方坯浇铸技术的发展

报导了国外连铸薄板坯及细小方坯,并在线直接轧成最后成品的技术发展情况,重点介绍了SMS/Nucor公司和MDH/Arvedi公司建设的两套生产设备。同时介绍了中国发展连铸薄板坯及细小方坯的情况。其中一种新型离心铸机是专为小型钢厂生产(60²～70²)mm²×1500mm细小方坯设计的,可为小型轧机提供坯料。     

微波等离子体CVD金刚石薄膜的显微结构

用扫描电镜(SEM)和透射电镜(TEM)对6种微波等离子体CVD金刚石薄膜的表面形态和显微结构进行了研究.结果表明:在金刚石晶粒长大过程中,(111)面方向长大时产生密度很高的微孪晶缺陷,而(100)面方向长大时产生的晶体缺陷较少.     

Pressureless Infiltration and Resulting Mechanical Properties of Al-AlN Preforms Fabricated by Selective Laser Sintering and Partial Nitridation

A novel manufacturing process has recently been developed for the fabrication of intricate Al-AlN composite parts. The process involves green shape formation by selective laser sintering, preform development by nitridation, and net shape forming by pressureless infiltration. The infiltration atmosphere has an important influence on the final fabrication and mechanical properties. This work presents a detailed investigation on the infiltration of Al-AlN preforms with AA 6061 at various temperatures above its liquidus under nitrogen, vacuum, and argon. The green shapes are formed by selective laser sintering of a premix of AA 6061-2Mg-1Sn-3Nylon (wt pct) powders. They are then partially nitrided to create a rigid, 2- to 3-μm-thick AlN skeleton for subsequent infiltration. Nitrogen infiltration results in the highest density (2.4 gcm⁻³) and best tensile properties (UTS: 214 MPa; elongation: 2.5 pct), while argon infiltration gives the lowest density. Fractographs confirmed the difference in density arising from the use of different atmospheres where small pores are evident on the fracture surfaces of both argon and vacuum-infiltrated samples. The molten AA 6061 infiltrant reacts with nitrogen during infiltration leading to a 5-μm-thick AlN skeleton compared to the original 2- to 3-μm-thick skeleton in both argon and vacuum-infiltrated samples. Transmission electron microscope (TEM) examination revealed inclusions of Mg₂Si and Mg₂Si _x Sn_1−x in both nitrogen- and argon-infiltrated samples but not in vacuum-infiltrated samples. Vacuum infiltration is slower than nitrogen and argon infiltration. The mechanisms that affect each infiltration process are discussed. Infiltration under nitrogen is preferred.