Damage behavior of the NiCrAlY coating systems with or without barrier layer during three-point bending

With the aid of three-point bending test the mechanical behavior of the NiCrAlY coating systems with or without barrier layer was analyzed. Together with the results from tensile adhesion test the damage mechanism of the investigated systems was discussed. It is found that the damage behavior was mainly dependent on the interfacial adhesion and the overlayer property. With a strong or weak interfacial adhesion and the brittle or ductile overlayer different damage mechanism was developed during test. The presence of residual stress and brittle precipitates or flaws at the coating/substrate interface influenced the interfacial adhesion property. The thermal exposure treatment improved the interfacial strength and the overlayer ductility.