Research progress in methods for inhibiting interdiffusion between single crystal superalloys and thermal barrier coatings

Abstract

Currently， the surface working temperature of second-generation or more advanced single crystal superalloy blade is above 1050 ℃， resulting in serious interdiffusion between coating and substrate. The interdiffusion not only consumes the beneficial elements of the coating and then reduces its service life， but also leads to the formation of secondary reaction zone in the substrate， which will seriously damage the high-temperature mechanical performance of the single crystal superalloy. Preparing diffusion barriers and designing the low inter-diffusivity coatings are effective ways to control the interdiffusion between thermal barrier coatings and single crystal superalloy substrates. Firstly，based on the latest international and domestic research progresses， the design principles， characteristics and classification of diffusion barriers were introduced briefly， and then the main problems and related research studies of metal diffusion barriers， ceramic diffusion barriers and active diffusion barriers were analyzed. Secondly， the application and latest progress of low inter-diffusivity coatings were reviewed， and the high-temperature protection properties and anti-diffusion mechanisms of nanocrystalline coatings， equilibrium coatings and γ′-based coatings were discussed in detail. Finally， the future development directions of different diffusion barriers and low inter-diffusivity coatings were pointed out.

Keywords

• single crystal superalloy
• thermal barrier coating
• interdiffusion
• secondary reaction zone
• diffusion barrier