• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Diffusion barriers for silicon carbide particle reinforcements by ion-beam assisted deposition: Effects on interphase stability in silicon carbide(p/beta)-nickel aluminide and silicon carbide(p/gamma)-nickel aluminide composites .
【24h】

Diffusion barriers for silicon carbide particle reinforcements by ion-beam assisted deposition: Effects on interphase stability in silicon carbide(p/beta)-nickel aluminide and silicon carbide(p/gamma)-nickel aluminide composites .

机译：离子束辅助沉积增强碳化硅颗粒扩散的阻挡层：对碳化硅（p /β）-铝化镍和碳化硅（p /γ）-铝化镍复合材料中相间稳定性的影响。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

In this study, aluminum nitride and aluminum oxide films were used as diffusion barriers for SiC particles that were consolidated with β-NiAl and γ-Ni3Al matrices at temperatures of 1673 K and 1373 K, respectively. The focus of this study was to understand factors influencing the effectiveness of the diffusion barriers during the consolidation processes of the two composite systems.; The barrier films were deposited on SiC particles by ion-beam assisted vacuum evaporation during which the SiC particles were radiantly heated and acoustically levitated. The nitride film formed reactively on SiC particles, and consisted of 95% aluminum nitride (balanced with aluminum nitrate and oxide). The oxygen content in the nitride film was a result of the impingement of residual oxygen and water molecules in the deposition environment.; A voided globular structure of fine-grained clusters was found in a nitride film deposited on SiC particles at 593 K, which was attributed to the levitation of the particles and the deposition temperature. Nitride films deposited at a higher temperature of 793 K consisted of a fine-grained dense structure with few voids. The oxide film deposited at room temperature had a fine-grained dense structure with some globular features.; This study found that film material affected film's ability of retaining integrity during compositing process, which was important for the success of the barrier films. Annealed at 1673 K, grains in a nitride film (deposited at 793 K) coalesced to an average size of 0.5 μm that was comparable to the film thickness. Grain boundaries in the film were widened by the pore agglomeration, resulting in micro-cracks. The oxide film exhibited a similar phenomenon of uninhibited grain growth and micro-crack formation at a lower temperature of 1273 K. Both films failed to be an effective barrier in SiC/β-NiAl composite during the compositing process at 1673 K.; This study showed the influence of film structure on grain growth in films at high temperatures. With a voided globular structure, the nitride film deposited at 593 K experienced a grain growth that was primarily restricted within each individual grain clusters at elevated temperatures. Solid-state sintering at 1673 K densified the nitride film because of the film's originally voided structure. After annealing at 1673 K for 4 hours, an average 0.5 μm thick nitride film deposited at 593 K retained film integrity on SiC particles, and succeeded as a diffusion barrier in the SiC/β-NiAl composite.; This study indicated that the chemical reaction potential in a composite system was a critical factor in determining the effectiveness of diffusion barriers. SiC/γ-Ni3Al composite had a higher chemical reaction potential at 1373 K, comparing to SiC/β-NiAl system at 1673 K. Although being effective as a diffusion barrier in the SiC/β-NiAl composite at 1673 K, the same 0.5 μm thick nitride film (deposited at 593 K) did not protect the SiC particles in the SiC/γ-Ni3Al composite at 1373 K.; A cursory study performed in this research indicated that Ni has low diffusivities in aluminum nitride lattice. From a γ-Ni3Al source, the upper-bound lattice diffusivity was estimated to be 2.2 × 10−14cm2/sec at 1473 K. From a β-NiAl source, the upper-bound lattice diffusivity at 1673 K was estimated to be 5.8 × 10−14cm2/sec.
机译：在这项研究中，氮化铝和氧化铝膜被用作SiC颗粒的扩散阻挡层，它们分别在1673 K和1373 K的温度下与β-NiAl和γ-Ni 3 Al基体固结在一起。这项研究的重点是了解影响两个复合系统固结过程中扩散壁垒有效性的因素。通过离子束辅助真空蒸发将阻挡膜沉积在SiC颗粒上，在此期间辐射加热SiC颗粒并使之悬浮。氮化物膜在SiC颗粒上反应性形成，由95％的氮化铝（与硝酸铝和氧化物平衡）组成。氮化膜中的氧含量是沉积环境中残留氧和水分子撞击的结果。在以593 K沉积在SiC颗粒上的氮化膜中发现了细颗粒团簇的空球状结构，这归因于颗粒的悬浮和沉积温度。在793 K的较高温度下沉积的氮化物膜由细小的致密结构组成，几乎没有空隙。在室温下沉积的氧化膜具有细密的致密结构，具有一些球形特征。这项研究发现，薄膜材料会影响薄膜在复合过程中保持完整性的能力，这对于阻隔膜的成功至关重要。在1673 K退火后，氮化膜（沉积在793 K）中的晶粒聚结成与膜厚相当的0.5μm平均尺寸。膜中的晶界由于孔的聚集而变宽，从而产生微裂纹。该氧化物膜在1273 K的较低温度下也表现出相似的无抑制晶粒生长和微裂纹形成的现象。在1673 K的复合过程中，两种膜均不能成为SiC /β-NiAl复合材料的有效阻挡层。这项研究表明了薄膜结构对高温下薄膜生长的影响。具有空洞的球状结构，在593 K处沉积的氮化膜经历了晶粒生长，该晶粒生长在高温下主要受到每个晶粒簇的限制。 1673 K的固态烧结使氮化物膜致密，因为该膜最初是有空隙的结构。在1673K下退火4小时后，在593K下沉积的平均0.5μm厚的氮化物膜保持了SiC颗粒上的膜完整性，并成功地成为了SiC /β-NiAl复合材料的扩散阻挡层。这项研究表明，复合系统中的化学反应潜力是决定扩散屏障有效性的关键因素。与1673 K时的SiC /β-NiAl体系相比，SiC /γ-Ni 3 Al复合材料在1373 K时具有更高的化学反应电势。尽管它在SiC /β- NiAl复合材料在1673 K时，相同的0.5μm氮化膜（沉积在593 K）对3733 K的SiC /γ-Ni 3 Al复合材料中的SiC颗粒没有提供保护。在这项研究中进行的粗略研究表明，Ni在氮化铝晶格中具有低扩散率。从γ-Ni 3 Al离子源估计的上限晶格扩散率为2.2×10 −14 cm 2 / sec从β-NiAl源获得1473 K，在1673 K处的上限晶格扩散率估计为5.8×10 -14 cm 2 / sec。

著录项

  • 作者

    Cai, Zhiwei.;

  • 作者单位

    Michigan State University.;

  • 授予单位 Michigan State University.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2000
  • 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

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号