Available online at www.sciencedirect.com ScienceDirect Materials Today: Proceedings 5 (2018) 16032–16041 www.materialstoday.com/proceedings 2214-7853 © 2018 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of 14th International Conference on Nanosciences & Nanotechnologies (NN17). NN17 Effect of Isothermal Heat Treatment on Cyclic Life of Yitria Stabilized Zirconia and Gadolinium Zirconate Thermal Barrier Coating AD Johari a , SM Yunus b , SA Biyamin b , MM Rahman c , H Hasini c , A Manap c * a TNB Repair and Maintenance Sdn Bhd, Jalan Dato Mohd Sidin, 41000 Klang, Malaysia b TNB Research Sdn Bhd, No. 1, Kawasan Institusi Penyelidikan,, Jalan Ayer Itam, 43000 Kajang, Malaysia c Universiti Tenaga Nasional, Department of Mechanical Engineering, College of Engineering, 43000 Kajang, Malaysia Abstract The effect of isothermal heat treatment on the thermal cyclic life of yttria stabilized zirconia (YSZ) and gadolinium zirconate (GZ) thermal barrier coatings (TBCs) have been investigated. The purpose of the isothermal heat treatment is to simulate thermal exposure on the TBC in the gas turbine. Duplex YSZ TBC with YSZ as a topcoat and NiCrAly as a bondcoat and five-layered GZ TBC with GZ as the topcoat (GZ / 50 wt.%GZ+50 wt.%YSZ / YSZ / 50 wt.%YSZ+50 wt.% NiCrAly / NiCrAlY) were plasma sprayed onto Nimonic 263 substrates to a total thickness of 900μm using F4-MB gun. The isothermal heat treatment was performed at a temperature of 1100ºC for 100 hours with a heating rate of 250ºC/hour in an air furnace. The thermal cyclic tests were performed with the following cycle in an air furnace: heat up from 1000ºC to 1200ºC within 1 hour, dwell at 1200ºC for 5 minutes, water quench and oven dry. The cycle is repeated until 20% spallation of the coating. Result indicates that the isothermally heat treated five-layered GZ TBC has a better cyclic life than the duplex YSZ TBC and as-sprayed GZ TBC. © 2018 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of 14th International Conference on Nanosciences & Nanotechnologies (NN17). Keywords: Gadolinium zirconate; YSZ; TBC; five-layered; functionally graded * Corresponding author. Tel.: +603-8921 2020; fax: +603-8921 2113. E-mail address: abreeza@uniten.edu.my