The Preparation Process Of Thermal Barrier Coatings In The Liquid Core Heavy Mill Rolls

Researching on the effects of the laser remelting ZrO₂-8%Y₂O₃ coating prepared by plasma spraying on improving rolls’ life is the main content of this paper, which was determined by the missions completed and achievements during the last years.Laser remelting technology can improve the microstructure of the coating, eliminate layered stacked structure, reduce porosity, increase density, prompte the interface elements evenly spreading, improve the bonding strength of the coating and the substrate, improving the coating quality. Laser remelting process is the metallurgical process of fast melting and solidification, which including physical and chemical phenomena of complex heat transfer, mass transfer, convection, diffusion, phase transitions in the bath. Laser remelting process parameters directly affect the level of quality of the coating.First of all, According to the characters of laser remelting, a travel heat source combined with the surface loads was designed in consideration of the thermal physical parameters of material, latent heat, radiation and convection etc. A computing model of transient temperature field of three-dimension moving laser remelting Zr O2-8%Y2O3 coating prepared by plasma spraying on H13 hot die steel was built up with the employment of ANSYS parametric design language. Distribution of temperature field of the molten pool at a certain moment is studied and the influence of different process parameters on the temperature field is analyzed, the pool’s profile has been forecasted, which can be used to optimize the processing parameters.Secondly, Preparing metallographic specimen with the materials mentioned above, observing the inner organization structure of the coatings by SEM. The result is the laser remelting ZrO₂-8%Y₂O₃ coating is more compact and has less pores. Then we got the result that the coating is improved on hardness and the resistance of heat shockFinally, roll plates on the small two-high mill to observe the transformation of the coatings. Result says, laser remelting ZrO₂-8%Y₂O₃ coating can improving the roll’s life...