Spray coating technology for preparing high melting point coramic coating layer

Abstract

A process for preparing the high-smelting-point ceramic layer or ceramic-metal layer on the surface of substrate includes such steps as conventional pre-treating on the surface of substrate, charging the powder material to be sprayed in the cavity of spray gun, applying a high shock current to electrodes, electric explosion for preheating and pushing said ceramic powder to the inlet of stage-2 spray gun, breaking through its electrode for generating high current and forming a plasma channel, heating and pushing the powder to move forward at high speed, and colliding with the surface of said substrate to form said ceramic layer.

Description

Technical field: [0001] The invention relates to a powder spraying process, in particular to a spraying process capable of spraying high melting point ceramic powder on a substrate. Background technique: [0002] Thermal spraying technology is to use the spraying method to prepare a certain thickness of coating material on the surface of the workpiece, so as to obtain the expected performance and function that the substrate does not have. It can significantly improve the corrosion resistance, high temperature resistance, oxidation resistance, and grinding performance, thereby significantly increasing the service life of components. [0003] Wear, fracture and corrosion are the three main forms of material failure. The economic losses caused by wear and tear are also enormous. In industrial countries, the loss caused by wear and tear accounts for 2 to 8% of the gross national product, of which only the loss caused by abrasive wear accounts for 1 to 4% of the gross national ...

AI Technical Summary

Problems solved by technology

But these technologies also have some limitations, as follows: (1) It is difficult to prepare some ceramic coatings with high melting point (2800-3830 ° C) (or coating performance is not high), such as HfC, NbC, TaC, ZrC, ZrB, TiC 、TiB 2 、B 4 C, etc. (These high-melting point coatings are very important for prolonging the life of some components working in 800-1500°C high temperature and corrosive environments)

(2) The traditional powder thermal spraying technology mostly uses the principle of gas thermodynamics to drive the powder movement, the powder speed is generally lower than 1000m / s, the coating and the substrate are mainly mechanically bonded, and the bonding strength between the coating and the substrate is low, generally Tens of MPa; for example, by plasma spraying B 4 C coating (coating used for the first wall material of nuclear reactor), its bonding strength is 10-20MPa, and the porosity is high, it is difficult to meet the engineering needs

Another is to use the electric explosion technology to explode the metal or alloy wire under the action of high current, so that the metal powder collides with the substrate to form a coating. This method cannot make non-metallic materials as coating materials, so how can non-metallic materials be used as coating materials? It is currently a technical problem to achieve a good bond coating between metal materials and substrates

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