Method for preparing metal surface laser strengthened coat

Abstract

The invention discloses a method for preparing a metal surface laser strengthened coat, which comprises the following steps: preparing uniformly mixed powder of titanium dioxide hydrate and graphite powder by using a wet chemistry method; pre-placing the mixed powder on the surface of a basal body; and irradiating the surface of the basal body by using laser as a heat source under an argon atmosphere to form a molten pool, performing a carbon-thermal chemical reaction on the pre-placed mixed powder under a high-temperature environment to generate titanium carbide, and finally forming a titanium carbide composite coat on the surface of the basal body. In the same way, the method is also suitable for preparing a TiN enhanced composite coat by mixing hydrated oxide thereof and graphite by the wet chemistry method, then mixing the mixture and urea to form pre-placed powder and cladding the pre-placed powder on the basal body by laser. The surface of the enhanced coat prepared by the technical scheme is smooth, and has no cracks or pores; enhancing particles are uniformly distributed in the coat; the enhanced coat and the basal body are metallurgically combined; and the mixed powder prepared by adopting the wet chemistry method is uniformly mixed, ensures complete reaction, and is suitable for industrial popularization and application.

Description

technical field The invention belongs to the field of metal composite materials, and in particular relates to a method for preparing an in-situ TiC or TiN composite coating. The reinforced composite coating prepared by the invention is suitable for surface strengthening of molds, tools and other wearable parts. Background technique In various industrial sectors, during the normal use of many mechanical devices, due to the frequent contact and collision between the working surface and the workpiece to be processed, it will cause a certain degree of abrasion and erosion on the surface of the mold. Over time, the entire set of molds will fail due to excessive wear. The industry often needs to spend a lot of manpower, money and time to replace components that are prematurely scrapped due to excessive wear and tear. If these components are made of cemented carbide, their service life can be improved, but this will also cost a lot. The current solution is to prepare a reinforcem...

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Problems solved by technology

However, the disadvantages of this method are: firstly, there is a difference in the thermal expansion coefficient between the strengthening layer and the matrix, which is easy to crack and affects the bonding force of the interface between the two; secondly, titanium carbide has a high melting point and low density. During the cladding process, titanium carbide particles in the molten state are easily embedded on the coating surface, making the prepared coating rougher; finally, titanium carbide particles are easy to agglomerate during the cladding process, which affects the uniformity of coating performance.

However, the disadvantages of this method are: firstly, the price of pure titanium powder is relatively high, and it is prone to oxidation; secondly, it is very difficult to mix the two powders evenly, and uneven powder mixing will affect the reaction formation of the strengthening phase titanium carbide , and at the same time cause the coating performance to vary within the region, affecting the overall performance

However, the disadvantages of this method are: First, the strengthening phase TiC is the direct combination of element Ti and element C through atoms, and its total equation is: Ti+C→TiC, because the formed TiC crystal structure and the structure of metal Ti and graphite They are not the same, so the energy required for the reaction is higher and it is not easy to fully react; secondly, the mixed powder is mixed by manual grinding, the mixing effect is not ideal, it is only suitable for a small amount of experiments, and it cannot be popularized and applied in industry, and the uneven powder mixing will affect The reactive formation of titanium carbide, the strengthening phase, also causes regional differences in coating performance, affecting overall performance

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