Failure Analysis of Multilayered Suspension Plasma-Sprayed Thermal Barrier Coatings for Gas Turbine Applications

Abstract

Improvement in the performance of thermal barrier coatings (TBCs) is one of the key objectives for further development of gas turbine applications. The material most commonly used as TBC topcoat is yttriastabilized zirconia (YSZ). However, the usage of YSZ is limited by the operating temperature range which in turn restricts the engine efficiency. Materials such as pyrochlores, perovskites, rare earth garnets are suitable candidates which could replace YSZ as they exhibit lower thermal conductivity and higher phase stability at elevated temperatures. The objective of this work was to investigate different multilayered TBCs consisting of advanced topcoat materials fabricated by suspension plasma spraying (SPS). The investigated topcoat materials were YSZ, dysprosia-stabilized zirconia, gadolinium zirconate, and ceriayttria-stabilized zirconia. All topcoats were deposited by TriplexPro-210 TM plasma spray gun and radial injection of suspension. Lifetime of these samples was examined by thermal cyclic fatigue and thermal shock testing. Microstructure analysis of as-sprayed and failed specimens was performed with scanning electron microscope. The failure mechanisms in each case have been discussed in this article. The results show that SPS could be a promising route to produce multilayered TBCs for high-temperature applications.

Durability of Gadolinium Zirconate/YSZ Double-Layered Thermal Barrier Coatings under Different Thermal Cyclic Test Conditions

“…Lu et al and Smialek et al previously reported the critical TGO thickness at failure in TCF tested specimens to be approximately 7–8 µm [30,31,32]. The failed specimen does not show blue failure, indicating the presence of alumina in the failed region of TGO [33].…”

Thermal barrier coating debonding defects detection based on infrared thermal wave testing technology under linear frequency modulation heat exitation

“…The thermal barrier coating (TBC) is one of the best high temperature protective coatings at present, with the characteristics of heat insulation, corrosion resistance, wear resistance and erosion resistance, has been widely used in power machinery, aerospace and other high temperature and high heat flow environment [1,2]. During the service of TBC, defects such as cracking, debonding and even peeling of coatings are easy to occur, which will affect the operation safety and reliability of hot end components, and even have catastrophic consequences.…”

Influence of inhomogeneous porosity on effusion cooling

“…Additive manufacturing has been widely applied to biomaterial [14][15], aerospace [16][17][18], building [19,20] and so on. Recently, additive manufacturing technology brought revolution in gas turbine industry [21][22][23]. SIEMENS has finished its first full load engine tests for gas turbine blades produced using Additive Manufacturing technology in the early of 2017 [24].…”