EFA-DATA

2.1. Coating preparation The TBC system consisted of one 150-μm-thick NiCoCrAlTaY bondcoat deposited by vacuum plasma spraying (VPS, Oerlikon Metco, Wohlen, Switzerland), and one 8YSZ top-coat deposited by an atmospheric plasma spraying (APS, Oerlikon Metco, Wohlen, Switzerland) using an F4MB-XL plasma gun. Ni-based superalloy plates (GH3128, Beijing CISRI-GAONA Materials & Technology Co., Ltd., China) with a dimension of 25 mm × 25 mm × 2.7 mm were selected as substrates. The chemical composition and size distribution of powder for bondcoat and top-coat (P1, P2, P3) were displayed in Table 1. The as-sprayed coatings (N1, N2, N3 and N4) with a thickness of approximately 900 μm, 950 μm, 1000 μm, and 950 μm. N1 and N2 TTBCs were prepared by two kinds of powder (P1 and P3, P1 and P2), successively. P1 and P2 powder was corresponding to N3 and N4 coating, respectively. Detailed spraying parameters were given in Table 2. The microstructure and XRD patterns of the powder were shown in the Fig. 1. 2.2. Thermal shock test The thermal shock tests were performed in the tube furnace (SLG 1400–50, Shanghai Shengli Test Instrument Co., Ltd., China) by heating and the water quenching method. The specimens with substrate were heat treated at the temperature of 1100 ◦C for 30 min and then put into the cold deionized water quickly, followed by compressed air drying and a macroscopical observation. When a visible  delaminated region reached about 10% of total coated surface, the test was stopped and the number of cycles to spallation was defined as the thermal shock lifetime of each sample. The aim of performing thermal cycling tests was to comprehend the microstructure changes in the TTBCs under abrupt temperature variations. 2.3. Coating characterization Microstructural and composition of the coatings were examined by scanning electron microscope (SEM, S-4800, HITACHI, Tokyo, Japan) coupled with energy dispersive X-ray spectrometry (EDS, SwiftED3000, Oxford Instruments, UK). Metallographic cross sections needed to be prepared for all samples to investigate the failure modes. The phase constituents of as-sprayed coatings and thermal shocked samples were characterized by an X-ray diffraction (XRD, D/max 2550 V, Rigaku Japan) with filtered Cu Ka (40 kV, 40 mA) radiation at a scan rate of 4◦ min− 1 in the 2θ range of 10-90◦. Phase and crystallographic analysis were carried out by electron backscatter diffraction (EBSD, NordlysNano, Oxford, UK). The scanning area was approximately 5100 μm2, and the step size was 150 nm. In particular, Ion Milling Device (EM TIC3X, Leica, Germany) was necessary in the preparation process of corresponding samples for EBSD characterization.