Microstructure and bending resistance performance of sprayed NiCoCrAlY sealing coating anchored by circular oscillating laser

A novel pinning-process using circular oscillating laser is utilized to improve the performance of NiCoCrAlY sealing coatings prepared by atmospheric plasma spraying. the stirring effect of the oscillating laser and Marangoni convection affect the outline morphology of pinned area, promote the recrystallization of the sprayed coating, eliminate the initial defects, transform the bonding behavior, and improve the mechanical property. The microstructure of the circular oscillating laser pinning area becomes compact, and the grain size is significantly refined, with an average size of 4.50 mu m. The combination between the coating and the substrate changes from mechanical bonding to metallurgical bonding. The enhanced uniformity of the microstructure in the laser pinning region resulted in a decrease of the microhardness by 5.6%. Furthermore, the pinning process increased the toughness of the coatings by 29 % in yield strength from 470 MPa to 600 MPa, and by 20 % in maximum failure strength from 1160.91 MPa to 1392.97 MPa.