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Sintering of nickel with and without dispersed alumina particles.

机译:有和没有分散的氧化铝颗粒的镍的烧结。

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摘要

Spheroidal nickel powder was treated with a fine dispersion of alumina by reaction with aqueous aluminum nitrate. Compacts of pure and dispersoid-treated powder were sintered in 5%{dollar}rm Hsb2/Nsb2{dollar} using both dilatometry and quenching to investigate densification and microstructural evolution. Isothermal and constant heating rate sintering were studied.; The sintering data were analyzed using the combined stage sintering model derived by Hansen, Rusin, Teng, and Johnson (1992). A method was outlined for predicting densification behavior based on a minimal number of trial experiments. The model was modified to include the effect of a dispersion of inert particles on sintering.; Densification was predominantly by grain boundary diffusion. The sintering activation energy of pure metal compacts was 174 kJ/mole, in excellent agreement with tracer values of grain boundary diffusivity.; Values of the microstructural geometry parameter of the sintering model, {dollar}Gammasb{lcub}rm b{rcub},{dollar} rose sharply between 80-85%, coincident with the onset of grain growth; this was attributed to a measured rise in the number of pores per grain, which decreased the diffusion distance. {dollar}Gammasb{lcub}rm b{rcub}{dollar} was much lower in magnitude and had a different dependence on density than predicted by the traditional intermediate stage sintering models. However, {dollar}Gammasb{lcub}rm b{rcub}{dollar} calculated from the present data coincided remarkably well with values calculated from data of other studies of nickel and alumina, suggesting that the grossly idealized geometry assumed by the traditional intermediate stage models accounts for these differences.; Computer simulations of sintering based on the combined stage model and using measured values of {dollar}Gammasb{lcub}rm b{rcub}{dollar} and grain size from isothermal sintering agreed well with constant heating rate sintering experiments.; Dispersed alumina particles at 100 ppm concentration inhibited the sintering of nickel powder at lower temperatures. The extent of inhibition increased with alumina concentration, but disappeared at high temperatures. The apparent activation energy for dispersoid-treated compacts at high temperatures agreed with those of the pure metal. The data were interpreted in terms of an interface reaction mechanism.
机译:通过与硝酸铝水溶液反应,用氧化铝的细分散体处理球形镍粉。使用膨胀法和淬火法在5%rmrm Hsb2 / Nsb2 {dollar}中烧结纯粉和经分散体处理的粉末,以研究致密化和微观组织演变。研究了等温和恒定升温速率烧结。使用Hansen,Rusin,Teng和Johnson(1992)推导的组合阶段烧结模型分析了烧结数据。概述了一种基于最少数量的实验来预测致密化行为的方法。对模型进行了修改,以包括惰性颗粒分散对烧结的影响。致密化主要是通过晶界扩散。纯金属压块的烧结活化能为174 kJ / mol,与晶界扩散率的示踪值极吻合。烧结模型的微观结构几何参数的值在80-85%之间急剧上升,与晶粒长大相吻合。这归因于测得的每个晶粒的孔数增加,这减少了扩散距离。与传统的中间阶段烧结模型所预测的相比,Gammasb {lcub} rm b {rcub} {dollar}的幅度要低得多,并且对密度的依赖性不同。然而,根据当前数据计算出的{dollar} Gammasb {lcub} rm b {rcub} {dollar}与根据镍和氧化铝的其他研究数据计算出的值非常吻合,这表明传统中间阶段所假定的完全理想的几何形状模型解释了这些差异。基于联合阶段模型并利用等温烧结的测量值和等温烧结得到的晶粒尺寸的计算机模拟烧结与恒定加热速率烧结实验非常吻合。 100 ppm浓度的分散氧化铝颗粒在较低温度下抑制了镍粉的烧结。抑制程度随氧化铝浓度的增加而增加,但在高温下消失。经分散体处理的压块在高温下的表观活化能与纯金属的表观活化能一致。数据是根据界面反应机理来解释的。

著录项

  • 作者

    Rusin, Richard Paul.;

  • 作者单位

    Northwestern University.;

  • 授予单位 Northwestern University.;
  • 学科 Engineering Materials Science.; Engineering Metallurgy.
  • 学位 Ph.D.
  • 年度 1993
  • 页码 193 p.
  • 总页数 193
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;冶金工业;
  • 关键词

  • 入库时间 2022-08-17 11:50:07

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