Corrosion behaviour of multi-layered plasma sprayed Gd 2 O 3 doped YSZ coating on Ni based super alloys A.M. Kamalan Kirubaharan b , A. Anderson a,⇑ , M. Rajasekaramoorthy a , S. Durgaprasad a , P.M. Manjuvardhan a a School of Mechanical Engineering, Sathyabama Institute of Science and Technology, Jeppiaar Nagar, Chennai, India b Centre of Nano Science and Nano Technology, Sathyabama Institute of Science and Technology, Chennai, India article info Article history: Received 7 June 2020 Received in revised form 6 July 2020 Accepted 9 July 2020 Available online xxxx Keywords: Ceramic multilayer coating Rare earth materials Oxidation behaviour High temperature abstract Nickel based superalloys are widely used in production of turbine blades. Although these materials have acceptable mechanical properties at high temperatures, they do can operate upto 700–800 °C but corrode and oxidise at temperatures above this. Generally, thermal barrier coating is used to safeguard the tur- bine blades at high temperatures. Commonly Yttria stabilized Zirconia TBC System is employed. This thermal barrier coating provides a great thermal and oxidation protection upto 1200 °C and fails above this temperature. In order to increase the oxidation resistance of nickel base superalloy, gadolinium oxide doped yttria stabilized zirconia coating mixed in varying percentages is applied on the surface of super- alloy by air plasma spray coating process. The salt spray corrosion test is carried out to analyse the cor- rosion behaviour of all the TBC compositions to be studied. Ó 2020 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the International Confer- ence on Future Generation Functional Materials and Research 2020. 1. Introduction Thermal barrier coatings help the engines to operate at higher gas temperatures [1]. Inconel-718, which mainly consists of Nickel showed good mechanical behaviour at high temperature condi- tions at two ends of the spectrum and is most commonly used in jet engines and gas turbine operations. Inconel-718 are used in all the major parts of aircraft gas turbines such as disks, combus- tion chamber, casings, shafts, exhaust system, blades, vanes, bur- ner, cans, stack gas re-heaters [2]. This Super alloy is been used in major areas including aerospace, automotive industries due to its minimal thermal degradation, resistance in oxidation, good mechanical behaviour and excellent resistance at high tempera- tures [3]. Corrosion resistance can be further enhanced by applying thermal barrier coatings on its surface. The materials used for TBC have low thermal conductivity and high thermal resistance. Coat- ing these materials on the surface of the material provides a layer of protective coating. Yttria stabilized Zirconia (YSZ) is the most commonly used protective coating which helps the metal substrate operate at 1200 °C without losing its integrity. But, above this tem- perature, Yttria stabilized Zirconia coatings failed due to Calcium Magnesium Alumino Silicates attack (CMAS) [4] and phase trans- formation from tetragonal to monoclinic phase. In this work YSZ is doped with gadolinium oxide at varying compositions since rare earth materials like gadolinium oxide (Gd 2 O 3 ) resist CMAS attack [5]. Air plasma spray technique [6] is used to coat the gadolinium oxide doped YSZ on the Inconel-718 in this work. In this work, corrosion performance of the coating will be studied using salt spray corrosion test. The salt spray test is a standard procedure to determine the ability of a material to resist corrosion when exposed to NaCl environment [7]. By visual inspection [8] and weight loss [9], the suitability of coatings to resist corrosion can be determined. In this study, a salt spray corrosion test (SSCT), rather than an immersion test, was conducted to evaluate the corrosion behaviour of the YSZ doped gadolinium oxide at varying compositions. The particular goal of this research is to determine the most optimum coating compositions using the corrosive test of standardized envi- ronmental effects. 2. Experimental procedure Inconel-718 substrates of 120 mm  30 mm  5 mm dimen- sions were cut using wire cut electrical discharge machining due to its minimum or negligible effects on the material after cutting. The substrates were grit blasted by using coarse alumina particles https://doi.org/10.1016/j.matpr.2020.07.153 2214-7853/Ó 2020 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the International Conference on Future Generation Functional Materials and Research 2020. ⇑ Corresponding author. E-mail addresses: kamalankiruba@gmail.com (A.M. Kamalan Kirubaharan), chrisson100@gmail.com (A. Anderson). Materials Today: Proceedings xxx (xxxx) xxx Contents lists available at ScienceDirect Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr Please cite this article as: A. M. Kamalan Kirubaharan, A. Anderson, M. Rajasekaramoorthy et al., Corrosion behaviour of multi-layered plasma sprayed Gd 2 O 3 doped YSZ coating on Ni based super alloys, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2020.07.153