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1990 Fiscal Year Final Research Report Summary

Modification of Refractory Metals by CVD and Its High Temperatutre Oxidation Resistance

Research Project

Project/Area Number 01470062
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field 金属材料(含表面処理・腐食防食)
Research InstitutionTokyo 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) SUSA Masahiro  Tokyo Institute of Technology Faculty of Engineering Research Associate, 工学部, 助手 (90187691)
NAGATA Kazuhiro  Tokyo Institute of Technology Faculty of Engineering Associate Professor, 工学部, 助教授 (70114882)
Project Period (FY) 1989 – 1990
KeywordsCVD / Pack cementation / Siliconizing / Aluminizing / Molybdenum / High temperature oxidation / Mo_3Al_8
Research Abstract

Demands for high strength materials for high temperature use is growing in energy related industries. The high temperature oxidation resistance of metallic materials is a key for the usage in oxidative environment. Refractory metals with high melting points such as molybdenum and tungsten are candidates for the base metals of metallic materials for high temperature use. However, these metals forms volatile oxides and suffer from severe oxidation. The oxidation resistance of metallic materials is provided by the formation of protected oxide scales of alumina, chromia or silica. In this study, aluminizing and siliconizing of the surface of molybdenum were carried out by pack cementation to form the protective alumina or silica scales in the oxidative environment.
Aluminizing provided the Mo_3 Al_8 coating layer in which cracks were easily introduced by the difference of thermal expansion between the coating and the Mo substrate and by the stress arising from the formation of alumina in the crack tips. The propagation of cracks during oxidation degraded the oxidation resistance. Silico-aluminized coating on molybdenum was per-formed by pack cementation at 1323 K. The coating was composed of Mo_3Al_8 containing about 1 at. % Si in which Mo (Si, Al)_2 and Mo_5 (Si, Al)_3 precipitated beneath the surface and at the coating/Mo interface, respectively. The oxidation of the coated molybdenum at 1520 K in air gave the thin alumina scale, exhibiting good oxidation resistance. The crack formation in the coating layer was seldom.
The microstructure of the coating layer was predicted by the phase diagram of Mo-Si-Al system at 1323K which was made by X-ray diffraction.

  • Research Products

    (8 results)

All Other

All Publications (8 results)

  • [Publications] 畢 暁〓,丸山 俊夫,永田 和宏: "モリブデン表面へのアルミニウムコ-ティング層の組織とその耐酸化性" 日本金属学会誌.

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Xiao Fang BI,Toshio MARUYAMA,Kazuhiro NAGATA: "Phase Diagram of MoーAlーS,System at 1323K" J.Less Common Metals.

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 畢 暁〓,丸山 俊夫,和田 和宏: "ケイ素ーアルミニウム 2段拡散処理によるモリブデンの高温酸化" 日本金属学会誌.

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Toshio MARUYAMA,Xiao Fang BI,Kazuhiro NAGATA: "SililoーAluminized Coating on Molybdenum and Its High Temperature Oxidation Resistance" High Temperature Corrosion of Advanced Materials.

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Toshio Maruyama et al.: "Silico-Aluminized Coating on Molybdenum and Its High Temperature Oxidation Resistance" High Temperature Corrosion of Advanced Materials.

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Xiao Fang BI ey al.: "Microstructure of Aluminized Coating on Molybdenum and Its High Temperature Oxidation Resistance" Nippon Kinzoku Gakkaishi.

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Xiao Fang BI et al.: "Phase Diagram of Mo-Al-Si System at 1323 K" J. Less Common Met.

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Xiao Fang BI et al.: "High Temperature Oxidation of Molybdenum Modified by the Two Step Pack Cementation of Silicon and Aluminium" Nippon Kinzoku Gakkaishi.

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1993-08-12  

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