Buckling of Graded Coatings. A Continuum Model
Abstract
Requirements for the protection of hot section components in many high temperature applications such as earth-to-orbit winged planes and advanced turbine systems have led to the application of thermal barrier coatings (TBCs) that utilize ceramic coatings on metal substrates. An alternative concept to homogeneous ceramic coatings is the functionally graded materials (FGM) in which the composition of the coating is intentionally graded to improve the bonding strength and to reduce the magnitude of the residual and thermal stresses. A widely observed failure mode in such layered systems is known to be interface cracking that leads to spallation fracture. In most cases, the final stage of the failure process for a thin coating appears to be due to buckling instability under thermally or mechanically induced compressive stress. The debonding and spallation problems are also observed in other layered material systems such as surface coatings in electronic devices and fiber? reinforced composite laminates. In the case of TBCs, stress concentrations due to interface asperities and voids and relatively low toughness of interfaces eventually lead to the formation of interface cracks or generally highly weakened interfacial zones. Buckling instability may then occur under sufficiently high compressive stresses.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 2000
- Accession Number
- ADA388678
Entities
People
- Tz-cheng Chiu
Organizations
- Lehigh University