Busso, E P*; Evans, H E*; Wright, L; Nunn, J; McCartney, L N; Osgerby, S* (2008) A software tool for lifetime prediction of thermal barrier coating systems. Mater. Corros., 59 (7). pp. 556-565.

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Abstract

In modern gas turbines thermal barrier coatings (TBCs) provide the key technology controlling the performance and lifetime of key components. It is therefore critical to be able to understand the mechanisms controlling the failure of TBCs and to predict these events. Most current approaches relate TBC failure to stress generation at or near the thermally grown oxide (TGO) that forms between the bond coat and the ceramic topcoat.

A full model of TBC failure requires characterisation of the coating system, identification of the key failure mechanisms, quantitative description of stress evolution in the key areas within the coating system and robust failure criteria for each failure mechanism. Thus the solution to lifetime prediction invariably requires massive effort both in terms of determining the appropriate input parameters for the model and in computing the solution.

This position can be alleviated through the use of interpolation techniques. Recently a model for TBC lifetime of an IN738/MCrAlY/EB-PVD system has been developed that predicts stress evolution at and near the TGO and relates these local stresses to several possible failure mechanisms. The stress distribution is dependent on time and temperature of exposures as well as the geometry of the bondcoat/ceramic interface and requires FE calculation for each specific set of conditions. In order to reduce the need for extensive calculation a software tool has been developed that interpolates the key stress values for each failure mechanism from a matrix of previously calculated values. Thus the failure of the TBC system can be readily calculated for other service conditions. The paper will describe the principles of the software tool and validation of the approach through comparison with non-destructive measurements on the coating system.

Item Type:	Article
Subjects:	Advanced Materials Advanced Materials > Thermal Performance
Last Modified:	02 Feb 2018 13:15
URI:	http://eprintspublications.npl.co.uk/id/eprint/4254

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