铸件凝固模拟液态孤立多熔池动态判定及缩孔预测

预测缩孔缺陷产生是铸件凝固模拟的主要目的。研究铸件凝固模拟液态孤立多熔池动态判定方法及缩孔预测模型，实验证明该方法可以提高铸件模拟缩孔预测精度。     

铸造CAD/CAE应用技术研究

基于凝固过程流场、温度场模拟(CAE)理论，进行了孤立溶池位置和大小的计算，判定其收缩体积，并结合数据库技术确定了冒口尺寸(CAD)。利用铸造CAD／CAE相结合的技术，对实际生产铸件进行了浇、冒铸造工艺的确定。研究表明，应用该CAD／CAE技术可快速制定铸造工艺，加快了产品研制开发周期。     

Stress relaxation of polymer melts subjected to large uniaxial tension

The stress relaxation behaviour of two molten amorphous polymers (PMMA and PS), has been investigated. The range of draw ratios extends to about 3.5 for PMMA and 7 for PS. The results have been compared with a modification of the original reptation model. The experimental results are fitted rather well by the theoretical predictions in all the range of tested draw ratios for both the materials used.     

Melt strength of calcium carbonate filled polypropylene melts

This paper investigates the extensional rheology (through melt strength measurement) of calcium carbonate (CaCO₃) filled polypropylene (PP) melts. Different concentrations of CaCO₃ filled PP were produced by mixing two master batches of pure PP and 70 wt% CaCO₃ filled PP in required proportions in a counter‐rotating twin‐screw extruder. It was found that the melt strength of the CaCO₃–PP melts was independent of CaCO₃ concentrations up to 25 vol%. Further increase in CaCO₃ concentration led to a severe reduction of melt strength. © 2002 Society of Chemical Industry     

Density of quaternary glasses in the MgO-CaO-Al2O3-SiO2-system—modeling vs measurement

The densities of quaternary glass-forming systems within the CaO-MgO-Al₂O₃-SiO₂-composition (CMAS) were evaluated. Their compositions differed not more than 5 mol% for each component from each other. After melting, the exact chemical compositions were measured using X-ray fluorescence and the densities were determined by Archimedes method and pycnometry. This property and its dependency upon small variations in the composition is the main focus of this paper. The density values were between 2.617 and 2.700 g/cm³ and the packing density factors V_p of the oxide glasses using the ionic radii of Pauling ranged from 0.562 to 0.574. The experimentally determined data were compared to different model calculations. Calculations performed according to empirical formulae given in the literature showed relative deviations between −5 and 12% to the experimental values. The effect of MgO was also studied by comparing the glasses with similar compositions (Ceram Int, 2016;42:5810–5822 ) without any MgO.     

HR-2不锈钢表面渗Al涂层的制备

为避免制备温度过高引起基体性能退化,采用了室温熔盐电镀与热处理复合技术在HR-2不锈钢卜进行了渗Al涂层制备研究,并对涂层的形貌、结构和成分进行了表征.结果表明,利用该技术制备渗Al涂层是可行的;经500℃和700℃两种温度下热处理,成功制得成分渐变,冶金结合且无缝隙和裂纹的10-15 μm厚渗Al涂层.经700℃下2 h热处理后,渗Al涂层与基体无明显界面,依次由(Fe,Cr,Mn,Ni)2Al5,(Fe,Cr,Mn,Ni)Al和(Fe,Cr,Mn,Ni)3Al3层组成;与700℃热处理后不同,经500℃下10 h热处理后,渗Al涂层与基体间界面明显,由内外两层组成.     

高聚物熔体挤出不稳定流动的研究进展

对近年来国内外关于熔体挤出不稳定流动现象的研究进展进行了介绍。阐述了关于形成鲨鱼皮和压力振荡及其他挤出不稳定流动的相关机理，并总结了抑制挤出不稳定现象所采取的措施。     

一个值得电解铝厂重视和采用的冰晶石替代方法

本文从冰晶石-氧化铝熔盐电解法(即霍尔-埃鲁法)的理论基础入手,简要分析了工业铝电解质的组成及过量电解质的产生原因,建议国内铝厂重视过量电解质的循环利用,逐步减少并替代冰晶石的使用,参与全球范围的过量电解质交易,有效盘活资源,降低新电解槽启动成本和生产成本。     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.     

铝硅酸钙熔体中氧原子的配位性质及动力学

采用分子动力学模拟研究了xAl2O3(1-x)(CaO·SiO2)系熔体中氧原子的配位及其动力学性质.实验发现:以Al为中心的次近邻的配位数总和大约为8,说明存在大量的三配位氧(triclusteroxygen,Ot).在对平衡构像的分析过程中发现主要存在2种形式的三配位氧:Ot(Al,Al,Si)和Ot(Al,Al,Al),但没有发现Ot(AL, Si,Si)和Ot(Si,Si,Si).另外,对存在的三配位氧的进一步分析表明这2种三配位氧还存在共棱和不共棱的精细结构.共棱现象只发生在AlO4四面体之间;而SiO4四面体之间,或者SiO4四面体和AlO4四面体之间不存在共棱现象.在此基础上,还对氧的均方位移及速度自相关函数等动力学性质进行了分析,发现三配位氧的增加明显降低氧原子的活动能力.