Thermal shock resistance of bimodal structured thermal barrier coatings by atmospheric plasma spraying using nanostructured partially stabilized zirconia

In this article, an agglomerated and sintered Y2O3-stabilized ZrO2 (YSZ) powder was introduced as a feedstock for atmospheric plasma spraying, and bimodal structured thermal barrier coatings with different contents of nano structure were deposited. Water-quenching method was carried out to study the effect of nanostructure content on thermal shock resistance of the coating. Results showed that the thermal cycle life of the coating is significantly influenced by the microstructure of the coating. When the nanostructure content was relatively low (about 39%), the coating showed high microhardness and poor thermal cycle life (failure at 11 cycles); however, when the nanostructure content was relatively high (about 60%), the coating showed lower microhardness and improved thermal cycle life (failure at 42 cycles); the coating with medium nanostructure (about 52%) showed the best thermal shock resistance (no failure at 50 cycles). The thermal stability of nanostructured coating was also investigated. After heat treatment at 1300 degrees C for 10 h, the nanoparticle size increased and the hardness of the coating increased noticeably, indicating the sintering effect of the nanostructured coating. (C) 2017 Elsevier B.V. All rights reserved.