Thermal shock behaviours of atmospheric plasma sprayed NiCrAlY/Al₂O₃–20%TiO₂ gradient coating on Cu–Be alloy

ABSTRACT

NiCrAlY/Al₂O₃–20 wt-%TiO₂ gradient coating on Cu–Be substrate was fabricated by atmospheric plasma spraying method. Effect of the phase composition and the microstructure of gradient coating on thermal shock behaviours were investigated by using the X-ray diffraction, scanning electron microscopy and energy dispersive spectrometry. The gradient coating shows a typical lamellar structure with a uniform thickness and good interface. The microhardness of gradient coating was 875 HV compared to the substrate of 199 HV. The thermal shock failure of gradient coating took place after 467 and 37 cycles at 400 and 600°C, respectively. The spallation boundaries of gradient coating with a step structure could be divided into three regions: coating spallation region (I), oxidation region (II) and coating region (III). The mechanism of thermal shock failure was discussed.

KEYWORDS:

• Plasma spraying
• gradient coating
• thermal shock
• failure
• Cu–Be alloy

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors are grateful to be supported by the National Natural Science Foundation of China [grant number 51561001], the Priority Academic Program Development of Jiangsu Higher Education Institutions [grant number 2018-03], the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions [grant number 2015–11], and the Science and Technology Project of Changzhou, People’s Republic of China [grant number CZ20180016 and CE20170028].