Coatings for Directionally Solidified Gamma Prime-Gamma Plus Alpha Eutectics.

Abstract

Coating compositions were developed to protect the directionally solidified gamma/gamma prime-alpha alloy (Ni-31w/oMo-6.2w/oAl) during cyclic oxidation and sulfidation in burner rig tests. The coating composition Ni-13.8w/oCo-15.8w/oCr-8.2w/oAl-16.9w/oPt-0.1w/oY was specifically identified in this study. For the family of alloys represented by gamma prime-alpha, the addition of 17 percent platinum to the NiCoCrAlY composition was insufficient to prevent cracking of the coating. Coatings containing 37 w/o platinum did not crack in the 2100 F cyclic oxidation tests. Chromium used as an intervening layer between gamma prime-alpha and the overlay coating reacted with the substrate to form brittle phases which cracked during thermal cycling. The substitution of nickel for chromium as an intervening layer resulted in void formation (Kirkendall porosity) leading to eventual coating delamination. (Author)

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Document Details

Document Type
Technical Report
Publication Date
Oct 01, 1979
Accession Number
ADA081934

Entities

People

  • John G. Smeggil

Organizations

  • United Technologies Corporation

Tags

Communities of Interest

  • Air Platforms
  • C4I

DTIC Thesaurus Topics

  • Alloys
  • Chemical Synthesis
  • Chemistry
  • Coatings
  • Corrosion Resistance
  • Gas Turbines
  • Gases
  • Heat Resistant Alloys
  • Heat Treatment
  • High Temperature
  • Laboratory Tests
  • Materials
  • Mechanical Properties
  • Metals
  • Physical Vapor Deposition
  • Thermal Expansion
  • Turbines

Fields of Study

  • Materials science

Readers

  • Powder metallurgy of Titanium alloys.
  • Surface Engineering/Surface Coating Technology.