Development of high-strength fiber for ultra high-temperature application by fast directional solidification method : control of microstructure

在这项研究中，我们在微计量尺度（纤维化）上应用了一种形状控制技术，以开发新的陶瓷原位复合材料，使其具有更高的强度，达到更高的温度。eutectic materials Y y在特定的情况下，开发出一种可在1700 ° C的空气大气层中的热稳定增强纤维，我们调查了具有良好控制的直径和微结构的高质量、均匀纤维的稳定增长的条件。微结构控制：我们已经确定了电子元件YAG和sapphire以及GAP和sapphire的相对方向，由TEM电子差异分析编写。这将在电子晶体的增长机制的演变中扮演一个关键角色。光纤直径控制：菜单很好地控制着坚硬的末端形状，我们在形状和纤维直径之间找到了牢固的关系。基于这一观测，我们可以在直径上生长出150微米的薄纤维。高温强度：我们在空气大气层和Ar在1500℃的房间温度下测试了张力强度，并测量了生长的电子纤维的基本物理性质，如热扩展协同等。张力强度在房间温度下达到930MPa，在1500℃的570MPa。

In this study, we applied a shape-control technique on the micrometer-scale (fiberization) for the development of new ceramic in-situ composite materials having high strength up to high temperature. The eutectic materials YィイD23ィエD2AlィイD25ィエD2OィイD212ィエD2(YAG)/AlィイD22ィエD2OィイD23ィエD2(sapphire) and GdAlOィイD23ィエD2(GAP)/sapphire were studied with the aim of reducing the microstructure from micro-scale to nano-scale in a controlled way. In particular, to develop a thermally stable reinforcement fiber which can be used at 1700℃ in air atmosphere, we investigated the conditions for stable growth of high quality, homogeneous fibers with well-controlled diameter and microstructure.1. Microstructure control : We have clarified the relative orientations of the eutectic components YAG and sapphire, and GAP and sapphire, by TEM electron diffraction analysis. This will play a key role in the elucidation of the growth mechanism of the eutectic crystal.2. Fiber diameter control : The meniscus was well controlled by the end shape of the crucible, and we found a strong relation between the shape and the fiber diameter. Based on this observation, we were able to grow thin fibers as small as 150μm in diameter.3. High temperature strength : We tested tensile strength at room temperature in air atmosphere and at 1500℃ in Ar, and measured fundamental physical properties of the grown eutectic fibers such as thermal expansion coefficient etc. Tensile strengths reached 930MPa at room temperature and 570MPa at 1500℃.