Fatigue properties of Fe-Al intermetallic coatings prepared by plasma spraying

In this research, FeAl based coatings were deposited on low carbon steel using two different plasma spraying technologies - gas stabilized plasma gun (GSP) and water stabilized plasma gun (WSP) - resulting in different deposition conditions. Significant changes in local chemical composition compared to feedstock material were observed due to uneven evaporation of Fe and Al from the molten material during the interaction of feedstock with plasma. Influence of coatings on substrate fatigue properties was characterized at room temperature using special testing device “SF-Test”. Fatigue lifetimes of specimens with different coatings were compared with those of uncoated specimens. Fractographic analysis of failed specimens revealed that substrate fatigue cracks initiated at coating-substrate interface and grew by striation mechanism. The coatings failed due to intrasplat cracking and intersplat decohesion.