Performance research of thermal shock resistance of laser remelting thermal barrier coating on roll surface

To improve the thermal shock resistance of roll surface coating and extend the service life under high temperature condition, plasma sprayed thermal barrier coating on the roll surface was remelted using 5kW CO2 laser. The coating surface morphology and microstructure of the laser remelting thermal barrier coating were observed by scanning electron microscopy. The micro-zone elements composition on the interface was analyzed by energy dispersive spectroscopy. By putting specimens at 1000℃ for 10min and then quenching into water directly, the thermal shock resistance was explored and compared with the plasma sprayed coating. The results show that porosity and crack of the laser remelting coating was reduced, and the quality of the coating was improved significantly. Metallurgical bonding was achieved between the coating and the substrate, and the adhesive strength was enhanced obviously. Thermal shock cycling times of the first crack and of the final failure was increased from 14 times and 32 times to 43 times and 94 times respectively. Laser remelting process is helpful to improve the thermal shock resistance of the coating and to extend the life of the roll.