Numerical investigation of residual stresses in high temperature ZrO₂ insulation coatings on Ag tape substrate for magnet technologies

In this research, the numerical investigation of residual stresses was carried out in high temperature ZrO₂ insulation coatings on Ag tape substrate for magnet technologies. ZrO₂ coatings were fabricated on Ag substrate using a reel-to-reel sol-gel system. The microstructural observation of ZrO₂ coatings was performed through an environmental scanning electron microscope (ESEM). ESEM micrograph revealed that ZrO₂ coatings with crack had mosaic structure which is suitable for high temperature insulation fields. The thermal stresses in the each layer were determined by the means of the lamination theory for both elastic solution and the finite element method (FEM) for elastoplastic solution in the temperature range of 298 to 50 K in liquid helium. The residual stresses happened throughout the production are neglected because of gradually cooling process. As a result of this, all of the residual stresses at the 298 K are accepted to be zero. Difference of thermal expansion coefficients and elasticity modulus cause the thermal stresses in the layers.