Feb_March_AMP_Digital

iTSSe TSS A D V A N C E D M A T E R I A L S & P R O C E S S E S | F E B R U A R Y / M A R C H 2 0 1 8 4 7 iTSSe TSS JTST HIGHLIGHTS 13 Fig. 5 − Porosity in the as-sprayed state evaluated by image analysis. FAILURE ANALYSIS OF MULTILAYERED SUSPENSION PLASMA-SPRAYED THERMAL BARRIER COATINGS FOR GAS TURBINE APPLICATIONS M. Gupta, N. Markocsan, R. Rocchio-Heller, J. Liu, X.-H. Li, and L. Östergren Improvement in the performance of thermal barrier coatings (TBCs) is one of the key objectives for further development of gas tur- bine applications. The material most commonly used as a TBC top- coat is yttria-stabilized zirconia (YSZ). However, the use of YSZ is limited by the operating temperature range, which in turn restricts engine efficiency. Mate- rials such as pyrochlores, perovskites, and rare earth garnets are suitable can- didates that could replace YSZ as they exhibit lower thermal conductivity and higher phase stability at elevated tem- peratures. The objective of this work was to investigate different multilay- ered TBCs consisting of advanced top- coat materials fabricated by suspension plasma spraying (SPS). The investigat- ed topcoat materials were YSZ, dys- prosia-stabilized zirconia, gadolinium zirconate, and ceria-yttria-stabilized zir- conia. All topcoats were deposited by TriplexPro-210 plasma spray gun and radial injection of suspension. Sample lifetime was examined by thermal cyc- lic fatigue and thermal shock testing. Microstructure analysis of as-sprayed and failed specimens was performed with a scanning electron microscope. The failure mechanisms in each case are discussed in this article. Results show that SPS could be a promising route to produce multilayered TBCs for high-tem- perature applications (Fig. 5).