Formation of Protective Oxide Scale with High Electrical Conductivity by High Temperature Oxidation of Alloys.

• Project/Area Number: 06453084
• Research Category: Grant-in-Aid for General Scientific Research (B)
• Allocation Type: Single-year Grants
• Research Field: Structural/Functional materials
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: MARUYAMA Toshio Tokyo Institute of Technology, Faculty of Engineering, Associate Professor, 工学部, 助教授 (20114895)
• Co-Investigator(Kenkyū-buntansha): NANKO Makoto Tokyo Institute of Technology, Faculty of Engineering, Research Associate, 工学部, 助手 (90272666) ; SUSA Masahiro Tokyo Institute of Technology, Faculty fo Engineering, Associate Professor, 工学部, 助教授 (90187691) ; NAGATA Kazuhiro Tokyo Institute of Technology, Faculty of Engineering, Professor, 工学部, 教授 (70114882)
• Project Period (FY): 1994 – 1995
• Project Status: Completed (Fiscal Year 1995)
• Budget Amount: ¥6,200,000 (Direct Cost: ¥6,200,000); Fiscal Year 1995: ¥2,300,000 (Direct Cost: ¥2,300,000); Fiscal Year 1994: ¥3,900,000 (Direct Cost: ¥3,900,000)
• Keywords: High Temperature oxidation / Highly conductive oxide scale / Sr-Cr-O system / Phase diagram / Standard Gibbs energy of formation / 固体燃料電池 / セパレータ / 導電率 / 標準生成自由エネルギー / SrCrO_4 / Sr_3Cr_2O_8 / Sr_3Cr_2O_7 / 高導電率酸化皮膜 / 標準生成自由エネルギ

Research Abstract

The highly conductive Cr_2O_3 scale was successfully obtained by high temperature oxidation of Cr_2O_3 formig alloys coated with (La, Sr) CoO_3. Microstructural analysis on the scale found that the Sr-Cr-Oxides precipitated in the scale and that the precipitates probably connected each other. The oxides are SrCrO_4, Sr_3Cr_2O_8, Sr_3Cr_2O_7, Sr_2CrO_4. The electrical conductivity of thses oxides were much larger than that of Cr_2O_3. To estimate the distribution of these oxides in the scale, the phase diagram in Sr-Cr-O system was constructed and the standard Gibbs energy of formation of these oxides weredetermined. These results are applicable to the design of the alloy separator in solid oxide fuel cell.

Research Products

• [Publications] Tohru SHIOMITSU: "The Influeme of (La,Sr) CoO_3 Coatings on Flcctricul Resislarce of Ni-20 CrAllcys" Proc.of 4th Fntem.Sympo on Solicl Oxiocle Fuel Cell. 850-857 (1995)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] Toshio Maruyama: "Elecfrical Coneclucfivily of SrCrO_4 and Sr_3Cr_2O_8 at Ezlevcted Teaperaturen in Relation to Highlyconcbehive Chumia Scale" Proc.of 4th Iutem.Sympo on Solid Oxile Fael Cell. 889-894 (1995)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] Thoru Shiomitsu: "The Influence of (La, Sr) CoO3 coatings on the Electrical Resistance of Ni-20Cr Alloys in High Temperature Oxidizing Atmosphere" Proc.of the 4th International Symposium on Solid Oxide Fuel Cells. 850-857 (1995)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] Toshio Maruyama: "Electrical Conductivity of SrCrO_4 and Sr_2Cr_2O_8 at Elevated Temperatures in Relation to the Highly Conductive Chromia Scale Formed on an Alloy Sepaarator in SOFC" Proc.of the 4th International Symposium on Solid Oxide Fuel Cells. 889-894 (1995)
  • Description: 「研究成果報告書概要(欧文)」より