铸件内析出性气孔形成及演化的直接观察与分析

采用透明模型合金实时观察了铸件析出性气孔的形成发展,结果发现,纯物质凝固时,析出性气孔的产生发生于凝固型壳形成之后,随着凝固自型壁向中心凝固,呈现自周边向中心的气条生长。对于合金凝固,析出性气孔在凝固基本完成之后伴随着热裂及缩松的发生开始产生,呈现一定的偏聚现象。浇注前熔体过热度的提高将使析出性气孔更加密集,铸型和环境温度的降低有利于降低气孔的数量及分布范围,采用真空除气,可有效地抑制析出性气孔的产生和热裂缩松缺陷的形成。     

高温合金中钛铌钨和钼的某些晶界析出行为

采用晶粒表面的萃取碳复型技术，观察研究了钛在一种具有大晶粒尺寸的高温合金中的晶界析出行为－晶界（Ti,Mo）C脆性包膜的形成和效应；不同含量的铌对一种高温合金晶界析出相类型、形貌分布、成分和数量的影响；分析讨论了钨和钼等元素对某些高温合金晶界碳化物和硼化物的析出行为存在的直接作用和间接作用。     

聚酯热熔胶溶胀制粉法的研究

聚醋热熔胶在其溶剂一沉淀剂混合液中加热“溶胀”后。再利用搅拌破碎而冷却成粉的方法。通过计算得到聚酯胶的溶解度参数(δ=21.8),参照比值选择溶剂和沉淀剂,并确定混合液的配比。文中还时制粉工艺和混合原料制粉的性能进行了研究。     

冷却速度对含钛高炉渣中钙钛矿相析出的影响

研究了冷却速度对攀钢含钛高炉渣熔体凝固过程中钙钛矿相晶体析出行为的影响、随着冷却速度的逐渐减小，钙钛矿相结晶量和晶粒度均随之增加，当冷却速度减小到0．5C／min时，钙钛矿相结晶量较多．枝晶得到明显粗化。同时也分析了钙钛矿晶体形貌特征和枝品粗化机理，为从钛渣中分离出钙钛矿相提供科学依据。     

原油正构烷烃沥青质聚沉机理研究及沉淀量测定

用IP 143标准方法测定了我国孤岛和草桥原油正构烷沥青质沉淀量。结果表明两种原油的沥青质沉淀量均随沉淀剂分子量增大而减小、随剂油比增大而增大。在原油沥青质 胶质胶束模型的基础上提出了一种新的沥青质聚沉机理 ,该机理的基本假设是原油中沥青质分子以胶束形式存在 ,其中胶核为沥青质缔合物 ,溶剂化层为胶质和溶剂分子。通过分析沉淀剂性质、剂油比、体系温度和压力等对沥青质 胶质胶束稳定性的影响得出了沥青质沉淀点、沉淀量、沉淀物平均分子量以及沉淀物平均颗粒大小随沉淀剂性质和剂油比等因素变化的规律。经比较说明 ,这些规律与本文及文献实验结果相符     

Preparation and properties of YAG nano-sized powder from different precipitating agent

Yttrium aluminum garnet (YAG) nano-sized powder was prepared by co-precipitation method assisted by ultrasonic display using different precipitating agent. The precursor powder can crystallize into YAG phase after being calcined at 900 °C for 2 h, because of the uniformly distribution of Al and Y elements. DTA–TG and IR measurements on the precursor powder obtained were performed to improve the synthesis process. X-ray diffraction was conducted on the powder calcined at different temperatures to investigate the effect of reaction conditions on particle size and phase composition. The powder about 15 nm in diameter with pure YAG was obtained at lower temperature (900 °C) by controlling the pH value, precipitating agent and doping agent.     

Cu-Zr-Te合金的时效特性研究

在Cu-Zr-Cr合金中采用Te元素代替合金中的Cr元素,从而避免了Cr6 可能产生的危害。分别对两种状态的Cu-Zr-Te合金进行时效工艺的研究,并采用扫描电镜(SEM)和能谱(EDM)分析了析出相的形貌和成分,以及时效工艺对合金材料的电性能及力学性能的影响。固溶 冷变形处理后的合金材料,在500℃下保温60min时效处理能使合金的综合性能优异。     

Comparative study of Cu/ZnO catalysts derived from different precursors as a function of aging

Structural modifications of Cu/ZnO catalysts for methanol steam reforming (MSR) as a function of precipitate aging in catalysts preparation process has been investigated comparatively. Freshly precipitated Cu,Zn-hydroxycarbonate (HC) and Cu,Zn-hydroxynitrate (HN) were aged in their mother liquor for a period of 120 min followed by washing, drying, calcination and reduction. Pronounced effect of aging was found for aged HC precipitates while no significant effect of aging was observed for aged HN solids. The bulk structure of the Cu/ZnO catalysts was investigated by means of TG/MS, in situ XRD and ⁶³Cu NMR. The increase in the activity of the catalysts prepared by HC aging did not correlate linearly with the specific Cu surface area but coincides with an increase in the microstrain in the copper clusters presumably because of the improved interface between Cu and ZnO. Meanwhile, aging of HN precipitates results in large, separated and less strained Cu and ZnO particles with an inferior catalytic activity. Finally, both aged Cu/ZnO catalysts revealed smaller copper crystallite size compared to unaged samples.     

关于沉淀过程在粉体制备中的几点思考

通过具体实例叙述了超细粉制备过程中ｐＨ值，胶凝速度及分散剂对粉体性能及制备过程的影响。说明对于不同的超细粉应根据具体的反应热力学及动力学综合考虑工艺方案，以使产品的成本，性能达到最佳组合，切实地使超细粉制备成为可能。     

废催化剂中钯的分离与提纯

钯资源非常有限 ,因此废旧催化剂等二次资源中的钯再生回收价值很高。废催化剂经过65 0℃以上高温处理 ,其中吸附的有机物即可完全分解 ,然后加入还原剂进行还原 ,使在高温处理过程中因氧化作用而生成的氧化钯全部被还原为金属钯。经过还原的废催化剂 ,可加入王水浸出钯 ,在 90℃浸出 2 5h ,钯的浸出率达到 99%以上 ;液固分离后 ,往滤液中加入沉淀剂沉淀出粗钯。将粗钯进行纯化处理可得纯钯 ,纯钯的品位符合国家标准 ,钯的回收率不小于 95 %。