Evaluation of fracture toughness in electrochemical interfaces composed of porous and dense ceramics

Research Project

Project/Area Number	20K22404
Research Category	Grant-in-Aid for Research Activity Start-up
Allocation Type	Multi-year Fund
Review Section	0301:Mechanics of materials, production engineering, design engineering, fluid engineering, thermal engineering, mechanical dynamics, robotics, aerospace engineering, marine and maritime engineering, and related fields
Research Institution	Gifu National College of Technology
Principal Investigator	Kumada Keigo 岐阜工業高等専門学校, その他部局等, 准教授 (40881652)
Project Period (FY)	2020-09-11 – 2024-03-31
Project Status	Completed (Fiscal Year 2023)
Budget Amount *help	¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000) Fiscal Year 2021: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000) Fiscal Year 2020: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Keywords	界面 / 靭性 / 固体酸化物燃料電池 / 界面破壊靭性値 / SOFC / 界面破壊靭性
Outline of Research at the Start	固体酸化物燃料電池はイオン伝導性のある緻密質セラミックスを電解質として、その両面に導電性および触媒機能を持つ多孔質セラミックスを電極として積層して構成される。この多孔質/緻密質セラミックス界面における破壊現象を明らかにすることは、機械的耐久性・信頼性の確保につながる。本研究では、燃料極還元処理の界面破壊特性へ及ぼす影響を明らかにし、界面破壊特性の劣化を抑制した高靭性SOFCの開発を目指す。
Outline of Final Research Achievements	The fracture energy at a porous-dense ceramic interface was evaluated using all-ceramic four-point bending specimens consisting of a thin porous NiO-8YSZ electrode layer sandwiched between two dense 3YSZ electrolyte beams. The Weibull plot of the interfacial fracture toughness data shows that the Weibull modulus was smaller than that of a single material of 3YSZ or NiO-8YSZ, and the variation of the interfacial fracture toughness was large. In addition, when the specimens were reduced and the electrode was changed to Ni-8YSZ, the interfacial fracture toughness tended to decrease.
Academic Significance and Societal Importance of the Research Achievements	SOFCの研究・開発では，構造・熱・流体・電気化学などを連成した高度なシミュレーションにより，セル内部応力の推定が行われている．これに対し，本研究により得られた界面破壊靭性値は界面はく離が発生するか判断するための基礎的なデータとして活用することが期待される．