Journal of the Korean institute of surface engineering (한국표면공학회지)

The Korean Institute of Surface Engineering (한국표면공학회)
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EFFECT OF ALUMINIDE-YTTRIUM COMPOSITE COATING ON THE OXIDATION RESISTANCE OF TiAl ALLOY

  • Jung, Hwan-Gyo (Pohang University of Science and Technology Center for Advanced Aerospace Materials) ;
  • Kim, Jong-Phil (Pohang University of Science and Technology Center for Advanced Aerospace Materials) ;
  • Kim, Kyoo-Young (Pohang University of Science and Technology Center for Advanced Aerospace Materials)
  • Published : 1996.12.01
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Abstract

Yttrium(Y) coating was incorporated by ion-plating method either directly on the TiAl substrate or after pack aluminizing on TiAl to improve the oxidation resistance of TiAl alloy. After Y-coating, heat treatment at low oxygen partial pressure was carried out. Performance of various coating was evaluated by isothermal and cyclic oxidation tests. A simple Y-coating without pack aluminizing can give a detrimental effect on the. oxidation resistance of TiAl alloy, because it enhances formation of $TiO_2$. On the other hand, a composite coating of aluminide-yttrium has shown excellent oxidation resistance. A continuous protective $Al_2O_3$ scale is formed on the aluminized TiAl, and Y-coating improves $Al_2O_3$ scale adherence and substantially prevents depletion of Al in the aluminide-coating layer.

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