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The mystery of molten metal

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China Foundry 2010年第4期7卷 425-437页

作者： Natalia sobczak jerzy sobczak Rajiv Asthana Robert Purgert Foundry Research Institute Department of Engineering & Technology University of Wisconsin-Stout Energy Industries of Ohio

Recent advances in scientific understanding of high-temperature materials processing using novel experimental methodologies have shed light on the complex role of surface and interface phenomena. New in-situ studies on molten metal/solid ceramic interactions using a unique experimental complex at the Foundry Research Institute, Krakow, have revealed a number of unusual observations in materials processing at high temperatures. We present some such unusual observations and their explanation with reference to liquid metal processing of Al, Ni, and Ti, and their alloys in contact with oxide ceramics. In particular, we focus on the following aspects: primary oxidation of Al from residual water vapor or oxygen, capillary purification to remove surface oxide, substrate protection by CVD carbon, roughening due to spinel whisker formation, inclusions in castings due to mechanical detachment, floatation due to buoyancy forces, and segregation due to directional solidifciation, modification of the solid surface morphology by metal vapor ahead of the liquid, and the complication due to multi-component alloys melted in crucibles made from complex oxide-based ceramics. In the case of Ti, rapid reactions with oxides result in undesirable volumetric changes that create difficulty in casting high-quality Ti parts, particularly by investment casting. Nanoscale (e.g., colloidal) coatings based on Y2O3 protect crucibles and hold ladles against such attack. Practical insights and recommendations for materials processing emerging from the fundamental studies on high-temperature interfacial phenomena have been described.

关键词： molten metal high-temperature phenomena in-situ observation casting defects

Structural and thermophysical properties characterization of continuously reinforced cast Al matrix composite

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China Foundry 2010年第4期7卷 456-462页

作者： Brian Gordon Natalia sobczak Ma gorzata Warmuzek Andrzej Gazda Lukasz Boroń Robert M.Purgert jerzy J.sobczak Touchstone Research Laboratory Ltd. Foundry Research Institute Energy Industries of Ohio

In this work the process of manufacturing a continuously reinforced cast Al matrix composite and its properties are presented. The described technology permits obtaining a structural material of competitive properties compared to either heat treatable aluminum alloys or polymer composites for several types of applications. The examined thermophysical properties and structural characterization, including material anisotropy, coupled with the results of previous measurements of the mechanical properties of both Al2O3 reinforcing filaments and metallic prepregs have proven the high quality of this material and the possibility of its operation under special loading modes and environmental conditions. Microscopic examinations (LM, SEM) were carried out to reveal the range of morphological homogeneity of the microstructure, the anisotropy of the filament band distribution, and simultaneously the adhesive behavior of the metal/fbier interface. The 3D morphology of the chosen microstructure components was revealed by computed tomography. The obtained results indicate that special properties of the examined prepreg materials have been strongly influenced, on the one hand, by the geometry of its internal microstructure, i.e. spatial distribution and volume fraction of the Al2O3 reinforcing filaments and, on the other hand, by a very good compatibility obtained between the individual metal prepreg components.

关键词： Al-MMC MetPreg alumina fibers microstructure thermophysical properties

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液态金属的奥秘

铸造 2010年第11期59卷 1155-1166页

作者： Natalia sobczak jerzy sobczak Rajiv Asthana Robert Purgert 波兰克拉科夫铸造研究所波兰克拉科夫30-418 威斯康星大学工程技术系美国WI54751 美国俄亥俄州能源工业美国OH44131

波兰克拉科夫的铸造研究所使用独特的多功能实验设备,原位研究液体金属与固体陶瓷之间的相互作用,揭示了材料高温处理方面的界面现象,涉及液态Al、Ni和Ti及其合金与氧化物陶瓷接触的处理工艺。主要包括:由残余水蒸气或氧引起的Al初始氧... 详细信息

波兰克拉科夫的铸造研究所使用独特的多功能实验设备,原位研究液体金属与固体陶瓷之间的相互作用,揭示了材料高温处理方面的界面现象,涉及液态Al、Ni和Ti及其合金与氧化物陶瓷接触的处理工艺。主要包括:由残余水蒸气或氧引起的Al初始氧化,用毛细管净化法去除表面氧化,用化学气相沉积碳防护基底,由于尖晶石晶须的形成造成的粗糙化,由于机械脱离导致的铸件夹杂物,因浮力产生的漂浮,因定向凝固发生的分离,用液体前沿的金属蒸气改性固体表面形态,在复杂氧化物基陶瓷坩埚中熔炼多组分合金的复杂性,钛与氧化物的快速反应导致不希望的体积变化,给生产优质钛铸件,特别是精密铸件,造成困难,用纳米尺寸(例如胶体)的Y2O3基涂层防护坩埚和保温包可以抵抗这种侵蚀。通过对高温界面现象的基本研究提出了对材料处理工艺的建议。

关键词：液态金属高温现象原位观察铸造缺陷

连续增强铸造铝基复合材料的结构特征和热物理性能

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铸造 2010年第12期59卷 1237-1243页

作者： Brian Gordon Natalia sobczak Malgorzata Warmuzek Andrzej Gazda Lukasz Boroń Robert M.Purgert jerzy sobczak 朱文高 Touchstone Research Laboratory Ltd. Foundry Research Institute Energy Industries of Ohio

介绍了连续增强铸造铝基复合材料的性能及其制造过程。该工艺能获得一种在某些应用场合中性能优于可热处理的铝合金或聚合复合材料的结构材料。检验得到的热物理性能和结构特征,包括材料的各向异性以及以前Al2O3增强纤维及金属预浸料坯... 详细信息

介绍了连续增强铸造铝基复合材料的性能及其制造过程。该工艺能获得一种在某些应用场合中性能优于可热处理的铝合金或聚合复合材料的结构材料。检验得到的热物理性能和结构特征,包括材料的各向异性以及以前Al2O3增强纤维及金属预浸料坯力学性能的测定结果都证明了该材料的高质量及其在特定的载荷模式和环境条件下工作的可能性。显微观察(光学显微镜,扫描电子显微镜)显示了微观组织的形态均匀性范围,纤维带分布的各向异性,以及金属/纤维界面的粘着特性。用计算机层析X射线照相法来显示所选取的微观组织组元的三维形态。结果表明:预浸料坯的特殊性能一方面受到其内在的微观组织几何形态,即Al2O3增强纤维体积分数和空间分布的强烈影响,另一方面还受到金属预浸料坯的各组元之间达到非常好的相容性的强烈影响。

关键词： Al基复合材料金属浸渍 Al2O3纤维微观组织热物理特性