Microstructure and Nanomechanical Behaviour of Electron Beam Evaporated Yttria Stabilized Zirconia Films on Ni Base Superalloy

Abstract

Yttria Stabilized Zirconia (YSZ) coating was developed using electron beam physical vapour deposition as a top coat material for thermal barrier application. In the present study, attempt to develop YSZ films by evaporating ZrO2 stabilized with 8 wt% Y2O3 powder using EBPVD technique. YSZ films were deposited on Inconel-718 (Ni-Cr-Fe) substrate by varying the substrate temperature in the range of 673 K to 1073 K. The deposited films have shown good adherence to the substrate and exhibit uniform dense microstructure. The effect of substrate temperature, phase and surface morphology were investigated by XRD, AFM and SEM. The film deposited at 673 K shows crystalline nature and the crystallinity of the deposited films increase with increasing substrate temperature. The surface roughness of the films increases with increase in the deposition temperature due to the increase in crystallinity of the films. SEM images shows that the films are grown with triangular shaped morphology. Nanomechanical characteristics of the tetragonal phase of the YSZ films were investigated by nanointendation technique and the young’s modulus of the coating was found to be 118 GPa.