Thermal stability of the CoWO4 layer formed on ferritic stainless steel

•Oxidation resistance of Co-W alloy coatings on ferritic stainless steel was investigated as a function of temperature.•Oxidation resistance was dramatically improved thanks to the presence of CoWO4 layer, and the coating is beneficial up to 850 °C•The thermal expansion coefficient of CoWO4 (11.5 ± 0.2 (×10−6 K−1)), was similar to that of Type430 (11–14 × 10−6 K−1), confirming good compatibility.•Growth kinetics of oxide layers formed from the Co-W coating was discussed as a function of temperature. This study focuses on the temperature capability of CoWO4 as the oxidation protection layer of ferritic stainless steel (FSS). The thermogravimetric-differential thermal analysis revealed that until CoWO4 started to melt at 1297 °C, little mass change was observed. In addition, the coefficient of thermal expansion of CoWO4 was 11.5 ± 0.2 (×10−6 K−1), which was similar to that of FSS, evidencing its good thermal stability and compatibility for the protection of FSS. The oxidation test of the Co–W coated specimens at 700 °C – 1000 °C in air confirmed effectiveness of the CoWO4 layer at T ≤ 850 °C.