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Investigation of rare earth alumino-silicate refractories for molten aluminum alloy containment.

机译：铝合金熔体用稀土铝硅酸盐耐火材料的研究。

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摘要

Several commercial alumino-silicate minerals doped with small amounts of light rare-earth oxides were tested for resistance to molten aluminum alloy attack. Although undoped compositions were severely attacked by aluminum alloy 7075, the addition of rare-earth oxides up to 15 percent by weight virtually eliminated the alloy attack. These rare-earth containing compositions were also resistant to the attack of Na{dollar}sb2{dollar}CO{dollar}sb3{dollar} containing alloy. The dopants CeO{dollar}sb2{dollar}, La{dollar}sb2{dollar}O{dollar}sb3{dollar} and bastnasite, a rare-earth concentrate, were all effective in rendering the alumino-silicate minerals resistant to alloy attack.; The addition of rare-earth oxide to bauxite was shown to alter its microstructure, forming a network of uniformly shaped corundum crystals interlinked with cerium containing strands. This unique microstructure was found to be primarily responsible for the enhanced attack resistance of the doped alumino-silicates. Several other possible mechanisms of protection were not supported by the experimental findings. Among these were enhanced sintering, the excess oxygen content of CeO{dollar}sb2{dollar} dopant and higher thermodynamic stability of the doped refractory compositions.; The lattice energies of crystals were calculated from a computer summation of the Coulombic interaction energies. After evaluating this technique using several simple crystal systems, the lattice energies of the light rare-earth (La through Eu) pyrosilicates, RE{dollar}sb2{dollar}Si{dollar}sb2{dollar}O{dollar}sb7{dollar}, were calculated. The lattice energies calculated for simple crystal systems were within 10% of the experimentally measured values. The enthalpies of formation for the rare-earth pyrosilicate were estimated from the calculated lattice energies by applying the Born-Haber cycle.
机译：测试了几种掺有少量轻稀土氧化物的商业铝硅酸盐矿物的抗熔融铝合金侵蚀的能力。尽管未掺杂的组合物受到铝合金7075的严重腐蚀，但是添加最多15％的稀土氧化物实际上消除了合金的腐蚀。这些含稀土的组合物还抵抗含Na {dolb} sb2 {dollar} CO {dollar} sb3 {dollar}的合金的侵蚀。掺杂剂CeO {dollar} sb2 {dollar}，La {dollar} sb2 {dollar} O {dollar} sb3 {dollar}和稀土精矿Bastnasite都能有效地使铝硅酸盐矿物抵抗合金侵蚀。;铝土矿中添加稀土氧化物会改变其微观结构，形成均匀形状的刚玉晶体网络，该网络与含铈的链相互连接。发现这种独特的微观结构主要是导致掺杂的铝硅酸盐的增强的抗侵蚀性。实验结果不支持其他几种可能的保护机制。其中包括增强的烧结，过量的CeO {sb2 {dolb}}掺杂氧含量和较高的热力学稳定性。从库仑相互作用能的计算机求和来计算晶体的晶格能。在使用几种简单的晶体系统评估了该技术后，轻稀土（La到Eu）焦硅酸盐，RE {dollar} sb2 {dollar} Si {dollar} sb2 {dollar} O {dollar} sb7 {dollar}的晶格能，进行了计算。为简单晶体系统计算的晶格能量在实验测量值的10％以内。稀土焦硅酸盐的形成焓是通过应用Born-Haber循环从计算出的晶格能量估算出来的。

著录项

  • 作者

    O'Brien, Michael Hughes.;

  • 作者单位

    Iowa State University.;

  • 授予单位 Iowa State University.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 1988
  • 页码 143 p.
  • 总页数 143
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;
  • 关键词

  • 入库时间 2022-08-17 11:50:50

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