Metal flange coated with insulating ceramic coating and preparation method thereof

Abstract

The invention discloses a metal flange coated with an insulating ceramic coating and a preparation method thereof. The insulating ceramic coating comprises the following material components in percentage by weight: 20 to 50 percent of TiO2 and the balance of Al2O3. The coating position comprises all outer surfaces of a metal flange substrate. The coating has a thickness between 0.1 and 0.6mm, a surface roughness less than or equal to 3.2mu m and a porosity less than 15 percent. The roughness of the substrate is not more than 3.2mum. The bonding strength of the coating and the substrate is more than or equal to 10MPa. All the angularity blend radius of the metal flange substrate is more than or equal to 1.0mm. The angularity radius of the coating is consistent with the round radius of the substrate. The invention makes the heterogeneous flange in a reliable electrical insulation state, and prevents the electrochemical corrosion as well as improves the work temperature of the flange from about 300 DEG C to about 900 DEG C.

Description

technical field [0001] The invention relates to a metal electrochemical corrosion protection and surface engineering technology, in particular to a metal flange coated with a ceramic insulating coating and a preparation method thereof. Background technique [0002] The piping systems of petroleum, chemical, electric power, ship and other facilities and equipment often have connections of dissimilar metal flanges such as valves and pipe joints. When exposed to seawater, sewage and other electrolytes or the environment is humid, galvanic corrosion will occur between heterogeneous flanges due to the difference in electrode potential, which will accelerate the corrosion of metals with lower potentials and affect the strength and sealing performance of the flanges. Flange insulation technology is to apply certain insulation measures to flanges. By increasing the resistance between flanges, the corrosion current can be significantly reduced, so as to achieve effective protection a...

AI Technical Summary

Problems solved by technology

[0010] (1) Low sealing reliability: insulating parts are prone to aging and damage, and have poor strength and are prone to failure, which affects the life and reliability of flange sealing;

[0011] (2) Not suitable for high temperature insulation: due to the poor temperature resistance of organic insulating parts, the operating temperature of insulating flanges generally does not exceed 300 °C;

[0012] (3) Poor insulation reliability: In addition to the easy failure of insulating parts and the reduction of insulation reliability, most of the existing technologies only insulate the end faces of flanges and fasteners, and other parts are exposed, thus increasing the distance between flanges. The danger of forming electrical conduction; this should also be the original intention of the "ship-to-shore connection insulating flange" technology to use insulating sheaths for flange flanges and apply insulating fillers between the flanges, but the use of sheaths and packing rings is undoubtedly Will increase the process and cost

[0013] (4) The corrosion of the flange by the environmental medium cannot be prevented: it is difficult to form a complete covering protective layer on the surface of the flange in the existing technology, so there is a lack of effective protection against the corrosion of the environmental medium

However, in the prior art, there is no similar patent document that achieves insulation protection by coating ceramic coatings on metal flanges

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