Measuring the Properties of Diffusion Aluminide Bond Coat Layers with Microsample Tensile Testing

Abstract

ABSTRACTThe bond coat layer plays an important role in the TBC system by providing oxidation resistance and a foundation for the ceramic top coat. The thermal cyclic durability of a TBC is thought to be strongly dependent on the physical and mechanical properties of the bond coat layer. Attempts to measure these properties for as-deposited and thermally cycled diffusion aluminide bond coats have been greatly inhibited by the limited thickness (∼60 μm) of these coatings. In the present study, novel high temperature microsample tensile testing technique is employed to measure the Young's modulus (E), coefficient of thermal expansion (CTE), yield strength and stress relaxation behavior of an as-deposited (Ni, Pt)Al bond coat in the temperature range of 25 oC to 1150 °C. Preliminary results for these material parameters are reported here. They are being used as material inputs for an independent finite element analysis (FEA) study of the development of stresses in the TBC layers during thermal cycling.