長谷川 誠  Makoto HASEGAWA
職   名:特別研究教員
       <学  部>生産材料科学実験T,
専   門:材料強度学,界面強度学
連絡先  :E-mail
● 研究テーマと概要 ●
(1) TiAl金属間化合物の高温加工と熱処理による組織制御と力学特性評価
(2) 熱遮蔽コーティングの熱的・力学的負荷におけるコーティングの信頼性評価

● 主な公表論文 ●
(1) M. Tanaka, M. Hasegawa and Y. Kagawa,” Detection of Micro-Damage Evolution of Air-Plasma-Sprayed Thermal Barrier Coating through TGO Stress Measurement”, Materials Transactions, 47 (2006) 1-6.
(2) M. Hasegawa and Y. Kagawa, “Change in Microstructure and Some Properties of NiCoCrAlY Bond Coat Layer by Heat Exposure in Air Plasma-Sprayed Y2O3-ZrO2 TBC Systems”, International Journal of Applied Ceramic Technology, 3 (2006) 293-301.
(3) M. Tanaka, M. Hasegawa, A.F. Dericioglu and Y. Kagawa, “Measurement of Residual Stress in Air Plasma-Sprayed Y2O3-ZrO2 Thermal Barrier Coating System using Micro-Raman Spectroscopy”, Materials Science and Engineering A, 419 (2006) 262-268.
(4) M. Hasegawa and Y. Kagawa, “Decohesion Behavior in Copper-Sapphire Interface under Mode I Cyclic Loading”, Materials Science and Engineering A, 417 (2006) 158-165.
(5) M. Hasegawa, S.J. Zhu, Y. Kagawa and A.G. Evans,” Effect of Metal Layer Thickness on the Decohesion of High Purity Copper-Sapphire Interfaces”, Acta Mater., 51 (2003) 5113-5121.

 High-temperature structural materials such as TiAl intermetallic alloys and thermal barrier coating systems (TBCs) are the target materials in our research group. Control of the lamellar orientation distribution in TiAl intermetallic alloys has been tried by high temperature deformation to realize excellent mechanical properties at ambient and high temperature. Figure 1 shows the typical microstructure of TiAl alloy where the lamellar orientation is controlled by high temperature deformation.
 Thermal barrier coating systems (TBCs) has been widely used in hot section components. It is composed of two layers: thermal barrier coating (TBC) and bond coat (BC) (Fig. 2(a)), and thermally grown oxide (TGO) which is formed in between TBC and BC (Fig.2 (b)) during the service. TBCs lose their function by the debonding in the coating. In order to elucidate the reason of the fracture in TBCs, mechanical test and residual stress measurement are performed on thermally and mechanically loaded TBCs.
Figure 1 Microstructure of lamellar orientation controlled TiAl intermetallic alloy.

Figure 2 SEM micrographs of APS-TBC system. (a) as-sprayed state, and (b) after heat exposure. TC: Y2O3 partially stabilized-ZrO2 thermal barrier coating, BC: NiCoCrAlY alloy bond coat, TGO: thermally grown oxide (Al2O3), Substrate: Inconel 738.