A novel crack healing in sprayed FeCrBSi coatings by plasma nitriding

In this study, the plasma nitriding technique was applied to heal the cracks of the FeCrBSi coating. Plasma nitriding was carried at 520 °C for 4, 8 and 16 h in an atmosphere of 75 vol% nitrogen and 25 vol% hydrogen. The crack-healing behavior of FeCrBSi coating was observed on the nitrided surface, and the healing effect becomes more noticeable as the nitriding duration increases. After 8 h of nitriding, the thickness of the nitrided layer reaches ∼12 μm and the surface hardness is the highest (c. 12 GPa). According to microstructural evolution, the healing mechanism of FeCrBSi coating by nitriding was investigated. •Plasma nitriding was applied to heal the cracks of the FeCrBSi coating.•Lattice expansion of Fe(Cr) and formed Cr2N cause the filling of cracks.•The mechanical properties were improved along with crack healing.