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首页> 外文学位 >Compacted oxide layer formation under conditions of limited debris retention at the wear interface during high temperature sliding wear of superalloys.
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Compacted oxide layer formation under conditions of limited debris retention at the wear interface during high temperature sliding wear of superalloys.

机译：在高温合金的高温滑动磨损过程中，在磨损界面处残渣保留有限的条件下，致密的氧化物层形成。

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The initial part of this study concentrates on sliding speed -- during the current experimental programme, testing was conducted at 0.314 m.s-1 and 0.905 m.s-1, between room temperature and 750°C -- this supplemented previous testing conducted at 0.654 m.s-1. When Nimonic 80A was slid against Stellite 6, lowering sliding speed to 0.314 m.s-1 between 510°C and 750°C lead to the formation of wear protective glaze layers consisting of cobalt and chromium oxides from the Stellite 6, whereas at 0.905 m.s-1 and during previous testing at 0.654 m.s-1, only high wear was encountered with debris consisting of nickel and chromium oxides from the Nimonic 80A. When Incoloy MA956 was slid against Stellite 6 at the same sliding speeds and over the same temperature range, a wear protective layer readily formed regardless of sliding speed. However, the sliding speed was observed to affect the relative contributions to the glaze layer from sample and counterface -- a shift was observed from largely cobalt and chromium oxides from the Stellite 6 at 0.314 m.s-1 to largely iron and chromium oxides from the Incoloy MA956 at 0.905 m.s-1. Also, the use of a higher sliding speed was noted to promote glaze formation at lower temperature, with glaze appearing at 450°C for 0.905 m.s -1, whereas only severe wear was observed for testing at 0.654 m.s -1.;When Incoloy MA956 was worn against Incoloy 800HT, increasing the sliding speed from 0.314 m.s-1 to 0.905 m.s-1 had the opposite affect -- the beginning of glaze formation was suppressed from 630°C to 690°C. Similar results were also observed when Nimonic 80A was slid against Incoloy 800HT, with the beginning of glaze formation suppressed from 570°C to 630°C. Thus whether sliding speed promotes or suppresses glaze formation is highly material dependant. Additionally, both the Incoloy MA956 versus Incoloy 800HT and the Nimonic 80A versus Incoloy 800HT combinations were characterised by high degrees of metallic transfer and especially at room temperature and 270°C, adhesive wear -- with Nimonic 80A versus Incoloy 800HT, the level of transfer, mostly from Incoloy 800HT to Nimonic 80A, was observed to increase with increasing sliding speed.;Further experimental studies concentrating on the sliding of Nimonic 80A versus Stellite 6 at 0.314 m.s-1 and 750°C, indicated extremely rapid formation of glaze from Stellite 6-sourced debris -- this consisted of an initial transfer of material from the harder Stellite 6 to the softer Nimonic 80A, followed by the steady development of a wear resistant glaze layer. The reversal of sample and counterface whilst varying sliding speed demonstrated that direction of transfer was more strongly influenced by material than configuration (i.e. which material was sample and which material was counterface). Finally, the substitution of Nimonic 80A with high purity nickel promoted the formation of glaze at not just 0.314 m.s-1, but also at 0.905 m.s-1 -- this was due to the elimination of chromium oxide (in the form of Cr2O3) from the predominantly nickel oxide (NiO) debris. This result, however, raises a number of queries yet to be answered. Firstly, why were nickel and chromium together readily able to form an oxide glaze with Nimonic 80A worn against Incoloy 800HT, but not so readily with Nimonic 80A worn against Stellite 6? Secondly, why did chromium readily form an oxide glaze with cobalt at 0.314 m.s-1 with the Nimonic 80A versus Stellite 6 combination, but not so readily with nickel at higher sliding speed?;Finally, nano-characterisation studies were carried out on the glaze layers formed on Nimonic 80A samples slid against Stellite 6 at 0.314 m.s -1 and 750°C. These glaze layers were shown to have a nano-scale grain structure, with a grain size of as little as 5 to 15 nm at the very surface of the glaze. A likely route of formation was established, starting with deformation of the surface, intermixing of debris from sample and counterface, oxidation of debris, further mixing and repeated welding and fracture -- these processes are aided by high temperature oxidation and diffusion. The grain size is then refined by the formation of sub-grains, accompanied by increasing mis-orientation to give nano-structured grains - a non-equilibrium state results, with poorly defined and irregular grain boundaries. The presence of a nano-polycrystalline structure implies improved fracture toughness. However, the disorganised nature of the glaze layer suggests the production of a glaze is, overall, an inefficient process. (Abstract shortened by UMI.)
机译：这项研究的最初部分集中于滑动速度-在当前的实验程序中，测试是在室温和750°C之间以0.314 ms-1和0.905 ms-1进行的-这是对之前以0.654 ms-进行的测试的补充。 1。当Nimonic 80A在Stellite 6上滑动时，在510°C和750°C之间将滑动速度降低至0.314 ms-1会导致形成由Stellite 6形成的由钴和铬氧化物组成的耐磨釉层，而在0.905 ms-如图1所示，并且在0.654 ms-1的先前测试期间，仅遇到由Nimonic 80A产生的由镍和铬氧化物组成的碎屑的高磨损。当Incoloy MA956以相同的滑动速度和相同的温度范围在Stellite 6上滑动时，无论滑动速度如何，都容易形成耐磨层。但是，观察到滑动速度会影响样品和相对面对釉层的相对贡献-观察到从0.314 ms-1的Stellite 6的大部分钴和铬氧化物转变为大部分的Incoloy的铁和铬氧化物MA956在0.905 ms-1。同样，注意到使用较高的滑动速度可促进在较低温度下的釉形成，釉在450°C时出现0.905 ms -1，而在0.654 ms -1时仅观察到严重磨损。Incoloy MA956在Incoloy 800HT上磨损，将滑动速度从0.314 ms-1增加到0.905 ms-1有相反的影响-釉料形成的开始从630°C抑制到690°C。当将Nimonic 80A相对于Incoloy 800HT滑动时，也观察到了相似的结果，釉的形成开始从570°C抑制到630°C。因此，滑动速度是促进还是抑制釉的形成在很大程度上取决于材料。此外，Incoloy MA956与Incoloy 800HT以及Nimonic 80A与Incoloy 800HT的组合均具有高度的金属转移特性，尤其是在室温和270°C下具有胶粘剂磨损-Nimonic 80A与Incoloy 800HT相比，转移水平观察到，主要是从Incoloy 800HT到Nimonic 80A随着滑动速度的增加而增加。;进一步的实验研究集中于Nimonic 80A与Stellite 6在0.314 ms-1和750°C下的滑动，表明Stellite形成釉的速度非常快六源杂物-包括材料从较硬的Stellite 6到较软的Nimonic 80A的初始转移，然后是耐磨釉层的稳定发展。在改变滑动速度的同时样品和对置面的反转表明，传输方向受材料的影响远大于结构（即，哪种材料为样品，哪种材料为对面）。最后，用高纯度镍代替Nimonic 80A不仅在0.314 ms-1时而且在0.905 ms-1时都促进了釉的形成-这是由于从中消除了氧化铬（以Cr2O3的形式）主要是氧化镍（NiO）碎片。但是，此结果引发了许多尚未回答的查询。首先，为什么镍和铬一起在Incoloy 800HT上佩戴Nimonic 80A就能容易地形成氧化釉，而在Stellite 6上戴着Nimonic 80A却不那么容易形成氧化物釉呢？其次，为什么在Nimonic 80A与Stellite 6组合下铬在0.314 ms-1时很容易与钴形成氧化物釉，而在较高的滑动速度下却不容易与镍形成氧化物釉；最后，对釉进行了纳米表征研究Nimonic 80A样品上形成的镀层在0.314 ms -1和750°C时相对于Stellite 6滑动。这些釉层显示出具有纳米级的晶粒结构，在釉的最表面处的晶粒尺寸小至5至15nm。建立了一种可能的形成途径，从表面变形，样品和对面中的碎屑混合，碎屑氧化开始，进一步混合以及反复焊接和断裂开始-这些过程都受到高温氧化和扩散的辅助。然后通过形成亚晶粒细化晶粒尺寸，并伴随着增加的错误取向，得到纳米结构的晶粒-形成非平衡状态，晶粒边界定义不规则和不规则。纳米多晶结构的存在意味着断裂韧性提高。但是，釉层的杂乱无章的性质表明，釉的生产总体上是效率低下的过程。 （摘要由UMI缩短。）

著录项

  • 作者

    Inman, Ian A.;

  • 作者单位

    University of Northumbria at Newcastle (United Kingdom).;

  • 授予单位 University of Northumbria at Newcastle (United Kingdom).;
  • 学科 Engineering Automotive.;Engineering Mechanical.;Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2004
  • 页码 369 p.
  • 总页数 369
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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