Abstract
The changes in physical properties of the crystallization roller prepared by different processing methods, as well as the stability of the WC-Cr₃C₂-Ni coating on it, were investigated in this study. The physical properties of the roller body treated by self-aging were the same as those of standard industrial treatment. The roller hardness reached more than 430.26 HV0.5, the thermal conductivity exceeded 105 W m⁻¹ K⁻¹ and exhibited good wear resistance. The rollers of different processing methods showed excellent bearing capacity for coatings. In the extreme service environment, the failure form of the coating on the roller surface was affected by the substrate hardness. When the hardness of the roller increased from 220.72 to 430.26 HV0.5, the failure cracks between the coating and substrate were close to the interface joint. The experimental results showed that both the non-industry standard aged treatment and the standard aged treatment can improve the performance of the roller body at this stage. The thermal shock life of the roller body was increased by 5.3 and 15.8 %, respectively, and the wear volume of the roller body was reduced from 7.05 x 10⁻³ to 5.23 x 10⁻³ cm³ and 5.02 x 10⁻³ cm³, respectively. At this time, the overall cost increase of the production line simulation budget was only 0.4 %, which was far lower than the 14.1 % of the roller that was completely replaced. This research effectively reduces the cost of innovation in the actual production of steel mills and provides theoretical support for other HVAF coating applications.

Key words
HVAF spraying, crystallization roller, WC-Cr₃C₂-Ni coating, processing method, economic benefit

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