PSI - Issue 17

Ekaterina M. Zubova et al. / Procedia Structural Integrity 17 (2019) 822–827 Ekaterina M. Zubova et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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arise. The destruction of the Thermal Barrier Coating (TBC) leads to decrease the composite material mechanical properties. Experimental study of the damage accumulation in composite material and ceramic coating is a relevant objective. There is a deficit in the ability to predict the damage evolution in coatings in terms of crack initiation and growth despite the progress made in recent years in analyzing the behavior and reliability of TBCs. And the last leads to crack and exfoliate the coating. But the detection of the cracks in the coating with the help of mechanical tests is difficult. Thus, mechanical tests and control with additional diagnostic systems, such as the method of acoustic emission and the correlation of digital images were combined to study the TBCs behavior. Contemporary authors are using the method of acoustic emission (AE) to study TBCs. In the works [Lee et al (2006), Park et al (2007)] samples with a TBCs were investigated by using AE. The amplitude, cumulative energy and the number of AE signals were evaluated. Authors [Yang et al (2007)] studied the generation of cracks in the TBCs with using of AE parameters analyzed, such as the number of events, amplitude, and frequency spectrum which were realized by using the Fast Fourier transform (FFT). Researchers [Yang et al (2014)] developed a shear-lag model for calculating the density of cracks on the surface of TBCs. In the same work, the method of digital image correlation was used to monitoring the cracks in TBCs under uniaxial compression tests.

2. Materials and methods

2.1. Materials and specimen geometry

In order to study the damage accumulation process in the coating during uniaxial quasi-static tension, the C/C composite material samples with a ceramic coating were tested. The photo of sample is shown in Fig. 1. Sketches of samples of C/C composite material are presented in Fig. 2. Ceramic coating was applied by plasma spraying using zirconium oxide powder stabilized with yttrium oxide on both sides of B surface. The coating thickness was 250 ± 50 μ m. Plasma coatings based on zirconium oxide have a high density, good adhesion with the substrate, and protect the substrate material from oxidation under the conditions of high-temperature oxidative gas flow.

Fig. 1. Photo of C/C composite materials samples with a ceramic coating.

B

Fig. 2. Sketches of samples for uniaxial tensile test.