*Article* **Structural-Phase Change of Multilayer Ceramics Zr-Y-O/Si-Al-N under High Temperature**

**Marina Fedorischeva 1,\* , Mark Kalashnikov 1,2, Irina Bozhko <sup>2</sup> , Tamara Dorofeeva <sup>1</sup> and Victor Sergeev 1,2**


**Abstract:** To increase the thermocyclic resistance of material, multilayer coatings with alternating layers of Zr-Y-O and Si-Al-N were obtained via magnetron sputtering. It was established that a coating layer based on Zr-Y-O has a columnar structure; the height of the columns is determined by the thickness of the layer. The Si-Al-N-based layer is amorphous. There were monoclinic and tetragonal phases with a large lattice parameter in the composition of the Zr-Y-O-based coating layer. After high-temperature annealing, a tetragonal phase with a small lattice parameter appeared in the microscope column. In the "in situ" mode, a change in the structural state of the Zr-Y-O coating layer was detected in the temperature range of 450–500 ◦C; namely, a change in the grain size and coherent scattering regions, and an increase in internal elastic stresses. It was found that the thermocyclic resistance increased by more than two times for multilayer samples compared to the single-layer ones we studied earlier.

**Keywords:** structure-phase state; multilayer coatings; grain size; curvature torsion; phase transition; thermal cyclic resistance
