Method for performing supersonic atmospheric plasma spraying of zirconium oxide on surface of crystallizer copper plate

Abstract

The invention relates to a method for performing supersonic atmospheric plasma spraying of zirconium oxide on the surface of a crystallizer copper plate. The method comprises the following steps: 1) performing surface pretreatment to a crystallizer copper plate matrix; 2) spraying a bonded coating on the surface of the pretreated matrix; 3) spraying a zirconium oxide base surface layer on the bonded coating; and 4) performing heat treatment to the product obtained in the step 3) and controlling the temperatures of the matrix and the coating below the matrix recrystallization temperature. By adopting the method, the bonding strength of the crystallizer copper plate matrix and the coating is high, the coating has high micro-hardness, low surface roughness and porosity and good high-temperature wear performance and thermal shock resistance. By applying the coating, the service life of the crystallizer can be effectively increased; and the coating can also be applied in the surface strengthening and repair of other copper or copper alloy elements.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgical continuous casting crystallizers, and in particular relates to a method for spraying zirconia with supersonic atmospheric plasma on the surface of a copper plate of the crystallizer. Background technique [0002] Continuous casting plays a key role in linking the past and the future between steelmaking and rolling processes in the field of iron and steel metallurgy, and the performance of the mold, which is called the "heart of continuous casting", has always been the focus of research. The modern continuous casting process requires the crystallizer to be at the highest possible casting speed to ensure that the slab shell has sufficient thickness when the slab leaves the mold to prevent leakage, and the thickness of the solidified shell around the slab is uniform to ensure the quality of the slab , The purpose of stable and efficient production to prevent leakage caused by billet drawin...

AI Technical Summary

Problems solved by technology

[0004] Electroplating has the following disadvantages: 1) There is a physical bond between the coating and the substrate rather than a metallurgical bond, and the frequent occurrence of cold and heat fatigue under the service conditions of the mold, the impact and friction of the molten steel and the billet often cause the coating to peel off; 2) There are defects such as pinholes and acicular porosity formed during the electroplating process inside the coating, which reduces the oxidation resistance and wear resistance of the coating; 3) The coating has low hardness and poor wear resistance; 4) Unavoidable sewage discharge during the electroplating process Waste discharge and environmental pollution are state-controlled and phase-out processes

However, the surface roughness of the coating prepared by the spraying process is large, and the strain resistance is poor, which affects the thermal shock resistance at high temperature, and there is no transition layer to ease the thermal expansion coefficient change between the coating and the substrate, which increases the temperature of the coating. The probability of thermal cracks at the meniscus leading to coating failure

Patent CN101302619A adopts supersonic flame spraying to prepare a nickel-based alloy coating with uniform thickness on the copper plate of the crystallizer with guard plates around it. The coating is metallurgically bonded to the substrate, reducing porosity and improving wear resistance, but The coating needs vacuum melting and diffusion heat treatment to enhance the bonding strength with the substrate. The heat treatment temperature is 800-950°C, which is higher than the recrystallization temperature of the copper substrate, which can easily induce thermal deformation of the copper substrate, thus increasing the difficulty of orthopedic treatment after heat treatment. process can jeopardize the performance of the coating

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