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    • Crack propagation studies and bond coat properties in thermal barrier coatings under bending

      A K Ray N Roy K M Godiwalla

      Volume 24 Issue 2 April 2001 pp 203-209

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      https://www.ias.ac.in/article/fulltext/boms/024/02/0203-0209

    • Keywords

       

      Coating; thermal barrier; bond coat; superalloy; crack propagation; zirconia; plasma spraying; stress; strain; modulus.

    • Abstract

       

      Ceramic based thermal barrier coatings (TBC) are currently considered as a candidate material for advanced stationary gas turbine components. Crack propagation studies under bending are described that were performed on plasma sprayed ZrO2, bonded by MCrAlY layer to Ni base superalloy. The crack propagation behaviour of the coatings at room temperature in as received and oxidized conditions revealed a linear growth of the cracks on the coating till the yield point of the super alloy was reached. High threshold load at the interface between the ceramic layer and the bond coat was required to propagate the crack further into the bond coat. Once the threshold load was surpassed the crack propagated into the brittle bond coat without an appreciable increase in the load. At temperatures of 800°C the crack propagated only in the TBC (ceramic layer), as the ductile bond coat offered an attractive sink for the stress relaxation. Effects of bond coat oxidation on crack propagation in the interface region have been examined and are discussed.

    • Author Affiliations

       

      A K Ray1 N Roy1 K M Godiwalla1

      1. National Metallurgical Laboratory, Jamshedpur 831 007, India

    • Dates

       
      Published
      April 2001

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