# Evaluation of the Residual Stress in ZrO2 Coatings Deposited on Different Substrates Through Image Relative Method

## TL;DR

This paper studies how substrate properties affect residual stresses in ZrO2 coatings using an image relative method, showing how temperature and material differences influence stress and deformation.

## Contribution

A method to analyze temperature-dependent residual stress in ZrO2 coatings using image relative analysis and Stoney’s formula is presented.

## Key findings

- Compressive residual stress forms during cooling due to lower thermal expansion of ZrO2 coatings compared to substrates.
- Residual stress and bending deflection increase with higher differences in thermal expansion and temperature.
- The image relative method effectively captures temperature-dependent residual stress in coated specimens.

## Abstract

What are the main findings?
Substrate characteristics determine residual stresses and deformations of the coated specimens.Temperature dependence of the residual stresses can be analysed via image relative method.The deformations of a single-side coated sample represent the form of residual stress.

Substrate characteristics determine residual stresses and deformations of the coated specimens.

Temperature dependence of the residual stresses can be analysed via image relative method.

The deformations of a single-side coated sample represent the form of residual stress.

What are the implications of the main findings?
The relationship among substrate characteristics, deformations and residual stresses is established.The challenge of evaluating residual stress at different temperatures is addressed.Promote the development of coated components used in high-temperature applications.

The relationship among substrate characteristics, deformations and residual stresses is established.

The challenge of evaluating residual stress at different temperatures is addressed.

Promote the development of coated components used in high-temperature applications.

In this work, the influences of substrate characteristics on the deformation and residual stress in ZrO2 coatings deposited on one side carbon steel, 316 stainless steel and 304 stainless steel are analysed via the image relative method. Based on the changes in bending deflection at different temperatures, temperature dependence of the residual stresses in the above three specimens was achieved through Stoney’s formula. Results show that a compressive residual stress is generated during the cooling process because the ZrO2 coating has a lower coefficient of thermal expansion (CTE) than that of the substrates. Additionally, by comparing the images of specimens under different temperatures, it can be found that the difference in CTE (∆α) between coating and substrate, as well as the temperature difference (∆T) between zero-stress temperature and testing temperature, determine the residual stresses in the coated specimens. And the higher the ∆α and ∆T, the higher the residual compressive stress and bending deflection. Moreover, temperature dependence of the residual stress could also be found through the image relative method.