Evolution of cracks within an Al2O3–40 wt%TiO2/NiCoCrAl gradient coating. Issue 17 (1st December 2018)

• Record Type: Journal Article
• Authors: He, Xuan; Song, Peng; Yu, Xiao; Li, Chao; Huang, Taihong; Zhou, Ying; Li, Qiaolei; Lü, Kaiyue; Lü, Jianguo; Lu, Jiansheng
• Is Part Of: Ceramics international. Volume 44:Issue 17(2018)
• Page Start: 20798
• Page End: 20807
• Publication Date: 2018-12-01
• Subjects: Gradient coating -- Al2O3 -- TiO2 -- NiCoCrAl -- Crack propagation; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2018.08.081
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: In this paper, an Al2 O3 –40 wt%TiO2 /NiCoCrAl gradient coating is deposited by atmospheric plasma spraying (APS). The microstructure and element distribution of the coating are studied by scanning electron microscopy (SEM) and electron probe X-ray microanalysis (EPMA). The crack propagation behaviour in the coating under applied and thermal stress is analysed through a three-point bending test and a thermal shock test, respectively. Two rapid propagation processes of the cracks can be found during the three-point bending test, which lead to two peaks in the load-displacement curves of the gradient coating. The gradual change in the composition also has an effect on the crack propagation process within the coating. Non-directional propagation paths of cracks and the formation of oxides can be observed in the gradient region under the effect of thermal stress, which lead to the spallation failure of the coating.