Simulation of temperature field and melting depth of an Y 2O 3-stabilized ZrO 2 thermal barrier coating sealed by high-current pulsed electron beam

Abstract

High-current pulsed electron beam is a promising technique for surface sealing of initially rough and porous Y 2O 3-stabilized ZrO 2 (YSZ) thermal barrier ceramic coatings. Due to the rapid remelting and solidification, the outer layer of the ceramic coating becomes smooth, dense and corrosion resistant such that the protective performance for turbine blades is enhanced. Because of the complex multi-layered structures, the high-current pulsed electron beam treatment requires specific parameter inputs which are related to the temperature fields induced by the electron energy deposition in the coatings. In the present work, a two-dimensional temperature field simulation is conducted to describe the temperature response and distribution in an Y 2O 3-stabilized ZrO 2 ceramic coating treated by high-current pulsed electron beam. The simulation reveals that the melting layer reaches a few micrometers in depth, and in particular at the pulse duration of 120 μs and the deposition energy density of 15 J/cm 2, the calculated melting depth of 4.4 μm is good agreement with the experimental results. The heating rate is up to 10 7–10 8 Ks − 1 and the temperature gradient is about 10 9 Km − 1 . It is pointed out that the ideal energy densities should be about 5–13 J/cm 2 at a pulse duration of 200 μs to seal the ceramic surface.