For intermediate temperature SOFC applications, metallic interconnects, such as Crofer 22H, have been used to replace ceramic interconnects in SOFC stacks because they are less expensive, more conductive and able to form complex shapes. Most metallic interconnects use chromium-containing alloy that form chromia scales at high temperatures. Since chromia may react with cathode and cause degradation, a protective oxide may be used to suppress the growth of chromia. Several techniques have been adopted to deposit oxides on metallic interconnects, thermal spray is found to be an appropriate technique. Thermal spray coating process has been used to produce a high quality coating by a combination of high temperature, high energy heat source, a relatively inert spraying medium, usually argon, and high particle velocities. This process allows the spraying of various types of metallic or ceramic coatings on to a wide range of substrate materials. As a result, uniform coating layer with excellent bond strength to substrate is obtained without noticeable distortion.

However, the temperature during thermal spraying may be high enough to change the crystal structure and conductivity of protective oxides. The heat treatment is believed to be an appropriate method to obtain adequate properties for protective oxide.

In this study, conducting oxides were deposited on metallic interconnect using plasma spray technique. However, the deposition temperature for thermal spray coating may be high enough to change the crystal structure and conductivity of protective oxide. The post annealing at elevated temperature is found to be an appropriate method to obtain adequate properties for protective oxide. Thus, the objective of this work is to investigate the effect of annealing on the crystal structure and conductivity of the sprayed oxide. The crystal structure, morphology and electrical conduction of interconnect with sprayed oxide films will be examined by using XRD, FESEM and resistance measurement.