Influence of ceramic thickness on residual stress and bonding strength for plasma sprayed duplex thermal barrier coating on aluminum alloy

• Published in: Surface & coatings technology Vol. 206; no. 21; pp. 4403 - 4410
• Main Authors: Gu, Lijian, Fan, Xizhi, Zhao, Yu, Zou, Binglin, Wang, Ying, Zhao, Sumei, Cao, Xueqiang
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-06-2012; Elsevier
• Subjects: Aluminum alloy; Applied sciences; Bonding strength; Coating; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Metals. Metallurgy; Nonmetallic coatings; Physics; Plasma spray; Production techniques; Residual stress; Surface treatment; Surface treatments; Thickness; Thickness; Bonding strength; Coating; Plasma spray; Residual stress; Aluminum alloy; Plasma; Mechanical strength; Spray coatings; Hot spraying; Surface treatments; Residual stresses; Ceramics; Non metal coating; Thermal barriers; Plasma arc spraying
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2012.04.070

NiCoCrAlY/8wt.%Y2O3–ZrO2 coating was plasma sprayed on aluminum alloy to evaluate the effect of ceramic thickness on residual stress and bonding strength. A new stress calculation method based on Stoney equation and substrate-removal technique was proposed. Stress in both bond coat and ceramic was studied. With the increase of ceramic thickness, the residual stress in both layers was firstly compressive then turned tensile. The large thermal expansion coefficient of the substrate played an important role in residual stress formation when the ceramic was thin. However, the intrinsic deposition stress took a dominant position when the ceramic coating turned thicker. The bonding strength decreased and the location of the fractured surface moved toward the ceramic surface. The moving of the surface was mainly resulted from the variation of stress gradient and the weakness of high porosity zone near the bond coat–ceramic interface.
► Duplex thermal barrier coating was deposited on an unconventional substrate. ► The residual stress was evaluated by combined use of two experimental methods. ► The influence of different ceramic thickness was investigated. ► The relationship between residual stress and bonding strength was clarified.