Study on microstructure and oxidation resistance properties at elevated temperature of FeCrAl coatings produced by high velocity arc spraying

FeCrAl coatings were prepared on low carbon steel substrate by high velocity arc spraying (HVAS) technology. The oxidation performance of coatings at elevated temperature was tested, microstructures of the sprayed and oxidized coatings were investigated. Results indicated that the as-sprayed coating was consisted of Fe-Cr amorphization mainly, together with crystallic phases such as Cr1.3-Fe0.7O3 and Fe-Cr solution crystals, which could be concluded that a very high cooling rate was obtained during HVAS process. The great mass of Al was oxidized during the spraying, which was existed in form of Al2O3. The oxidation resistances of coatings at elevated temeprature was much higher than that of 12Cr1MoV steel and approximately follows that of T91 steel. The excell oxidation resistances of FeCrAl coating was due to the chromium oxide pretective film would be formed at layers of the coating, moerever it was closely relation to the formation of Fe-Cr amorphization with high resistances to oxidizing. After being oxidatized at 800°C for 260 h, partial amorphization structures were crystallized and transformed into the fine Fe-Cr crystallic phase.