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首页> 外文学位 >Particle packing, compaction and sintering in powder metallurgy.
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Particle packing, compaction and sintering in powder metallurgy.

机译：粉末冶金中的颗粒填充，压实和烧结。

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摘要

This thesis focuses on the improvement of density based on the controlling of particle packing and the subsequent densification processes. First, the two-sphere model for monosized powder to determine the lattice diffusion contribution in sintering is considered. Based on Eadie's model, two new solutions are developed and presented, an upper limit solution with surface curvature at a maximum all along the neck and a more accurate solution in which the form of the surface curvature at the neck can be varied as appropriate. Producing bimodal powder distribution powder metallurgy (P/M) parts is next considered. It is shown that this technique is capable of producing parts with excellent final densities and mechanical properties. In order to explain the above experimental results, theoretical research about bimodal powder is focused on particle packing. The first theoretical tool is the coordination number of the particles and the second theoretical tool is the concept of percolation. A bridge is established between packing density, microstructure and leading eventually to macroscopic properties by using coordination number and percolation. A new model (modified saturated model) for coordination number in bimodal packing is developed and presented. It is concluded that the structures that arise in bimodal powder distributions he somewhere between the previously proposed random structure and the saturated structure. The important role of the coarse particle network which can shield fine particles from the compaction forces is emphasised. Some comments about parameters influencing sintering and suggestions for future work are included.
机译：本文基于控制颗粒堆积和随后的致密化过程，着重于提高密度。首先，考虑用于确定烧结过程中晶格扩散贡献的单一尺寸粉末的两球模型。基于Eadie的模型，开发并提出了两个新的解决方案，即在整个颈部最大表面曲率的上限解决方案，以及可以适当更改颈部表面曲率形式的更精确的解决方案。接下来考虑生产双峰粉末分布粉末冶金（P / M）零件。结果表明，该技术能够生产出具有优异最终密度和机械性能的零件。为了解释上述实验结果，关于双峰粉末的理论研究集中在颗粒堆积上。第一个理论工具是粒子的配位数，第二个理论工具是渗滤的概念。通过使用配位数和渗滤，在堆积密度，微观结构之间建立了桥梁，并最终导致了宏观性能。提出并提出了双峰包装中配位数的新模型（改进的饱和模型）。结论是，以双峰粉末分布出现的结构介于先前提出的随机结构和饱和结构之间。强调了可以阻止细小颗粒受到压紧力影响的粗颗粒网络的重要作用。其中包括有关影响烧结的参数的一些评论以及对未来工作的建议。

著录项

  • 作者

    Chen, Xiaolin.;

  • 作者单位

    University of Alberta (Canada).;

  • 授予单位 University of Alberta (Canada).;
  • 学科 Engineering Metallurgy.
  • 学位 Ph.D.
  • 年度 1998
  • 页码 194 p.
  • 总页数 194
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 冶金工业;
  • 关键词

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