Systematic Research on Hig-Strength and High Performance Ni-Base Superalloy Coatings for Advanced Gas Turbines.

先进燃气轮机用高强高性能镍基高温合金涂层的系统研究。

基本信息

批准号：
10555027
负责人：
OKAZAKI Masakazu
金额：
$ 8万
依托单位：
The University of Tokyo (1999-2000)Nagaoka University of Technology (1998)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

Collaborative research, which cover the themo-mechanical fatigue (TMF) and isothermal low-cycle fatigue (ILCF) strengths of Ni-Base superalloys and the protective coatings at elevated temperatures, has been carried out. Based on the observations of the crack initiation, the fracture surface and the dislocation structures, the effects of the substrate alloy and the coating on the TMF and ILCF lives are presented in this paper. The correlation between the TMF and ILCF are also discussed.The results obtained by the collaborative research are summarized as follows :(1) The TMF lives, as well as the ILCF, were strongly dependent of the substrate alloys. The single crystal and directionally-solidified alloys and their coatings generally exhibited the most excellent properties, compared with those of the traditional pollycrystalline alloy.(2) The observation of dislocation structures indicated that the controlling and deformation mechanisms were intrinsically different between TMF and ILCF in … More the Ni-base superalloys. Accordingly, it must be unreasonable in principle to reproduce and to estimate the TMF failure of the Ni-base superalloys by the ILCF tests.(3) Remarkable reductions in the TMF life of the Ni-base superalloy coatings under the out-of-phase condition was found to occur, compared with that of the substrate. It was shown by the investigation of the crack density that this was due to the low ductility of the coating film at the temperatures at which the maximum tensile strain was reached in the TMF tests, resulting in severe crackings. Hence, it is essential for the TMF life prediction of Ni-base superalloy coatings to get understandings not only on the substrate but also the coating film.(4) Regarding as the TMF failure of the coatings, attention should be paid to the results by ILCF tests which can provide us a somewhat misleading information : e.g., the TMF lives under the out-of-phase condition were significantly reduced by the coating, although the ILCF one at 900℃ was improved. Less

基于裂纹萌生的观察，开展了涵盖高温下镍基高温合金和保护涂层的热机械疲劳（TMF）和等温低周疲劳（ILCF）强度的合作研究。本文介绍了断裂表面和位错结构、基体合金和涂层对TMF和ILCF寿命的影响，并讨论了TMF和ILCF之间的相关性。合作研究获得的结果是。总结如下：（1）与传统多晶合金相比，TMF 寿命以及 ILCF 强烈依赖于基体合金，单晶和定向凝固合金及其涂层通常表现出最优异的性能。 (2)位错结构的观察表明，TMF和ILCF在镍基高温合金中的控制和变形机制存在本质上的不同，因此，从原理上讲，这是不合理的。通过ILCF试验重现并估计镍基高温合金的TMF失效。(3)与非相条件下相比,发现异相条件下镍基高温合金涂层的TMF寿命显着缩短。通过对裂纹密度的研究表明，这是由于在TMF试验中达到最大拉伸应变的温度下涂膜的延展性较低，从而导致了严重的裂纹。对于镍基高温合金涂层的TMF寿命预测至关重要，不仅要了解基体，还要了解涂层膜。(4)对于涂层的TMF失效，应关注ILCF试验的结果，可以给我们提供一些误导性的信息：例如，尽管在 900℃ 下的 ILCF 寿命有所改善，但异相条件下的 TMF 寿命因涂层而显着降低。