Elastic modulus and thermal stress in coating during heat cycling with different substrate shapes

Abstract

The elastic modulus of a deposit (E_d) can be obtained by monitoring the temperature (∆T) and curvature (∆k) of a one-side coated long plate, namely, a one-dimensional (1D) deformation model. The aim of this research is to design an experimental setup that proves whether a 1D deformation model can be scaled for complex geometries. The setup includes a laser displacement sensor mounted on a robotic arm capable of scanning a specimen surface and measuring its deformation. The reproducibility of the results is verified by comparing the present results with Stony Brook University Laboratory’s results. The ∆k-∆T slope error is less than 8%, and the E_d estimation error is close to 2%. These values reveal the repeatability of the experiments. Several samples fabricated with aluminum as the substrate and 100MXC nanowire (Fe and Cr alloy) as the deposit are analyzed and compared with those in finite element (FE) simulations. The linear elastic behavior of 1D (flat long plate) and 2D (squared plate) specimens during heating/cooling cycles is demonstrated by the high linearity of all ∆k-∆T curves (over 97%). The E_d values are approximately equal for 1D and 2D analyses, with a median of 96 GPa and standard deviation of 2 GPa. The correspondence between the experimental and simulated results for the 1D and 2D specimens reveals that deformation and thermal stress in coated specimens can be predicted regardless of specimen geometry through FE modeling and by using the experimental value of E_d. An example of a turbine-blade-shaped substrate is presented to validate the approach.

Graphical abstract

Keywords

in-plane / Young’s modulus / curvature temperature / thermal stress / coating

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Higher Education Press and Springer-Verlag Berlin Heidelberg