Effect of high-temperature annealings and creep on structure and properties of single- and double-layer heat-resistant coatings

Abstract

The evolution of the structure, phase, and chemical composition in the double-layer refractory heat-resistant plasma coatings and surface layers of ZhS6U alloy [Ni-(8–9)Cr-2,4Ti-5,3Al-(9–10)Co-(1,2-2,4)Mo-10,5W-1,0Nb–0,02B-(0,18–0,2)C] under a coating was investigated during high-temperature annealings and creep. The internal oxidation was observed in ZhS6U alloy under a single-layer coating of Ni-Cr-Al-Y alloy after high-temperature annealings and creep in air. The possibilities of inhibiting internal oxidation by the application of an additional barrier layer for oxygen diffusion were considered. It was shown that ion implantation does not lead to the suppression of internal oxidation in the alloy under a coating and does not significantly affect the long-term strength during creep at 1273 K. An additional ceramic layer delays the internal oxidation of ZhS6U alloy by 50–60 h, which leads to an increase in the time until destruction at a stress of 170 MPa from 100 h for an alloy with a single-layer coating to 120 h. The application of a sublayer of refractory alloys completely suppresses internal oxidation. A refractory alloy with a double-layer coating has the same long-term strength for 100 h both in air and under a vacuum.