State of the Art of Gadolinium Zirconate Based Thermal Barrier Coatings: Design, Processing and Characterization

Abstract

The fast consumption of fossil fuel resources and economic competitiveness makes it necessary to increase the efficiency of turbine engines. For this purpose, thermal barrier coating (TBC) has been used on some critical parts of gas turbines. Yttria-stabilized zirconia (YSZ) is widely and commercially used as a ceramic top coat material for TBC in the gas turbine system. On the other hand, the efforts to identify new material having better properties than YSZ have been continued. Gadolinium zirconate (GZ) is a promising alternative TBC material with its lower thermal conductivity, better sintering ability, and higher melting point and phase stability than YSZ. However, recent research studies on the responses of GZ-based TBC materials to the complex demands of modern gas turbine applications should be gathered under a study by comparing them with the results of traditional TBC material. This chapter discusses the GZ based TBC system, specifically addressing issues related to the production process and designing of the coating architecture, in comparison with some of the significant properties with YSZ and the test methodology. Moreover, the chapter also contains information about laser surface modification of the GZ-based TBC.

Low thermal inertia thermal barrier coatings for spark ignition engines: An experimental study

“…Comparatively, the penetrative depth of GZO was ∼125-microns at 1500 RPM based on the material properties listed in Table 5, thus the 200-micron GZO piston was below its penetrative depth by ∼25-microns. However, the variability in measured conductivity of GZO throughout the literature 26 implies that a range of ∼100-microns to ∼145-microns are possible penetrative depths. Based on the experimental results, it can be inferred that the true penetrative depth of GZO was closer to the latter.…”

“…Conductivity values are varied throughout the literature with reported values between 0.6 and 1.3 W/m/K. 26 For the purposes of this study, a midpoint conductivity was selected since the performance of the novel coating with respect to commercial materials is of interest.…”

SEM-Guided Finite Element Simulation of Thermal Stresses in Multilayered Suspension Plasma-Sprayed TBCs

“…Additionally, a very thin scale named thermally grown oxide (TGO) is formed and grows gradually along the TC/BC interface at high temperatures due to oxidation of the metallic BC [1,6]. The continuous demands for increasing the efficiency and performance of gas turbines engines by extending the working temperature limit (>1200 • C) have revealed certain issues associated with YSZ-TBC that need to be addressed, including a high sintering rate, the loss of phase stability, hot corrosion, and calcia-magnesia-alumina-silicate (CMAS) attack [7][8][9]. As a promising alternative to YSZ, gadolinium zirconate (GZ, Gd 2 Zr 2 O 7 ) is characterized by a lower sintering rate and thermal conductivity and better phase stability and resistance to CMAS attack [10,11].…”

Efficient Heat Shielding of Steel with Multilayer Nanocomposite Thin Film

“…The most common type of TBCs are ceramic-based, often utilizing zirconium oxide as a thermally grown oxide layer. , This type of ceramic layer exhibits a high thermal resistivity, partly because of relatively low thermal conductivity (0.8–2.25 W·m –1 ·C –1 ), that creates an obstacle to thermal transport, prolonging the life of the metal and allowing for operation both in high-temperature and in oxidizing conditions. − While zirconia coatings offer a high degree of protection to operation under extreme temperature (e.g., temperatures in excess of 1400 °C found inside turbine engines), they are also expensive and involve somewhat complex processing . As a result, these oxide layers are primarily used in high-value applications, such as gas turbine blades.…”