Cyclic Corrosion Behavior Of YSZ Thermal Barrier Coating And Properties Of A New Ceramic Layer YTa_1-xNb_xO₄

Thermal barrier coating（TBC）is a complex multifunctional structure（including ceramic layer TC,thermal growth oxide layer TGO and bonding layer BC）,which is widely used to protect the structural components of aviation and land gas turbines.With the rapid development of China’s marine economy,the performance requirements of gas turbine engines that have been in service for a long time in the marine environment continue to improve.At present,the environmental conditions and working modes experienced by the marine aero-engine are very different from those on land:the marine service environment is very bad,the blades are not only subject to the chemical corrosion and electrochemical corrosion of seawater,but also bear high temperature loads.In addition,the shipboard service also needs to consider the acid salt corrosion.Therefore,the main research idea of this paper is to simulate the real marine service environment,analyze the corrosion behavior and corrosion mechanism of the thermal barrier coating,reveal the location of the traditional thermal barrier coating short board,and carry out targeted optimization work.The specific research contents are as follows:XRD and SEM-EDS were used to analyze the failure behavior of 7YSZ thermal barrier coating system under cyclic acid salt corrosion at room/high temperature.The results show that with the increase of cycle period,the YSZ ceramic layer will undergo volume transformation and accelerate the coating failure;In addition,sodium chloride will corrode the whole thermal barrier coating system,but the most severely corroded area is the bonding layer,which becomes the short board of the thermal barrier coating system.Therefore,the corrosion resistance of the adhesive layer is improved by adding Co element to improve the corrosion resistance.The experimental results of acid salt cyclic high temperature oxidation show that the addition of CO in the bonding layer will reduce the diffusion rate of Al by 20%.However,the thermal barrier coating systems with or without Co element all have cracks at the tgo/tc interface and propagate to each structural layer,resulting in failure,which can not fundamentally solve the problem that the bonding layer is preferentially corroded,and the service life of TBC has not been significantly prolonged.In this paper,a new ceramic coating system is designed to improve the acid salt corrosion resistance of TBCs.YTa_1-xNb_xO₄ was selected as a new ceramic layer material in this paper.YTa_1-xNb_xO₄ powder material was prepared by coprecipitation method.It was found that YTa_1-xNb_xO₄ had a stable monoclinic phase,M phase.YTa_1-xNb_xO₄bulk material shows better phase stability than YSZ in the cyclic acid salt corrosion test at room/high temperature.The relevant fracture toughness of the material is obtained by indentation method.Further CMAS molten salt corrosion test results show that YTa_1-xNb_xO₄ has better fracture toughness and high temperature phase stability than YSZ material.