成果報告書詳細
管理番号20160000000319
タイトル*平成27年度中間年報 エネルギー・環境新技術先導プログラム 無冷却高圧タービン動翼を実現する最先端超高温材料の研究開発
公開日2016/5/17
報告書年度2015 - 2015
委託先名株式会社IHI 国立大学法人東北大学大学院工学研究科
プロジェクト番号P14004
部署名イノベーション推進部
和文要約
英文要約Research & Development of Advanced Ultrahigh-Temperature Materials for Uncooled High-Pressure Turbine Rotor Blades

1. Materials design for UH-MMC
For the metal matrix of the ultrahigh-temperature metal matrix composites (UH-MMC), five kinds of alloys having different melting points (1600-2000℃)2000℃) were designed and prepared by arc-melting. Using the 1st generation MoSiBTiC alloy (Mo65Si5B10Ti10C10(at.%)), it was demonstrated that melting and casting processes are technically available to provide a large ingot even for such a high-melting-point alloy. Consolidation of Mo, Al, and TiC or ZrO2 powders was attempted using a spark-plasma sintering process, and it was shown that Al reduces a part of ZrO2 and forms Al2O3 during the process. The achievements conduce the design idea that Al2O3 should be used in the metal matrix containing Al and ZrO2 is available in the matrix without Al as reinforcement.

2. 3D additive manufacturing for UH-MMC
We prepared Mo-Ti-Al powder by a powder blending method and fabricated Mo-Ti-Al alloy builds by SLM process. Mo powder and TiAl powder was mixed with various compositions. SLM was carried out for the mixed powders using a self-developed SLM apparatus with Yb fiber laser in Ar atmosphere. Mo and TiAl powder was successfully mixed without agglomeration. SEM observation revealed that the SLM builds containing TiAl-rich composition possessed relatively smooth bead surface, indicating that Mo and TiAl powders were alloyed during laser scanning. However, residue of Mo were confirmed in the Mo-rich compositions, and therefore the higher energy density should be introduced by controlling SLM parameters.

3. Melting and casting process for UH-MMC
The objective of this part is to develop Mo-based metal matrix composite (MMC) by infiltrating a Mo-based alloy liquid into Al2O3 or ZrO2 ceramic fillers with an original machine for this project. In the first year, we tried to prepare MoSiBTiC MMCs with the ceramic fibers by a prototype infiltrator. The results showed that the fibers were degraded when heated around 1600℃, which was lower than the infiltration temperature "1900℃", due to its SiO2 inclusion, although the infiltration itself was almost succeeded. Therefore, we gave up using MoSiBTiC matrix and these ceramic fibers for the filler materials, instead, NiAlMoCr and ceramic powders are respectively to be considered in the second year.

4. Hot-working processes for UH-MMC
In order to investigate the workability and oxidation property of developed Mo-base alloy, high temperature compression test and oxidation test were performed. Deformation resistance of Mo-Ti-Al and TiC added Mo-Ti-Al alloy were significantly decreased compared to MoSiBTiC alloy at 1400℃. Oxidation weight loss of these alloys at 1100℃ under air were less than MoSiBTiC alloy. But, oxidation penetrated into center of each tested sample due to absence of oxidation-resistant film on surface. Therefore it is necessary to add the protective material such as Al2O3 to Mo-base alloy in order to improve oxidation property.
The procedure for preparation of ultra high temperature alloy ingots was established. φ100×70mm test ingots such as MoSiBTiC alloy were melted successfully by conventional high frequency heating. We can produce powder sample or billets for Additive manufacturing technology or forging or casting from these test ingots.
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