Effects of plasma-sprayed NiCrAl/ZrO2 intermediate on the combination ability of coatings

A NiCrAl/ZrO2 composite coating was deposited on the surface of metal carri er FeCrAl alloy by a plasma-spray technique. After static-state oxidation a t 800 degreesC, the transitions in structure and composition of the coating was analyzed by XRD, SEM and EDX. The results showed that the surface phas es of the as-sprayed coating were mainly composed of Ni and ZrO2. When the oxidation time was extended from 8 to 50 h, NiO crystallites were formed an d these grew coarse on the coating surface, and alloy elements were diffuse d between the NiCrAl/ZrO2 coating and the FeCrAl substrate. With the pretre atment, an intermediate coating was prepared with a coarse and porous struc ture, high cohesive strength and high heat resistance. These developed prop erties could provide high geometric surface area for a catalytic gamma -Al2 O3 washcoat, and enhance the adhesive strength between ceramic washcoat and metal substrate so as to extend the lifetime of the washcoat. (C) 2001 Els evier Science B.V. All rights reserved.