Preparation process of densely-arranged columnar crystal ceramic coating based on laser remelting technology

Abstract

The invention discloses a preparation process of a densely-arranged columnar crystal ceramic coating based on a laser remelting technology. The preparation process comprises the steps of improving the remelting quality by using high frequency induction heating and ultrasonic vibration assisted processes while carrying out laser remelting on a nickel-based high-temperature alloy piece with a thermal barrier coating by using laser, wherein the thermal stress generated in a remelting process can be reduced and a large number of cracks generated when a ceramic layer is deeply remolten by using laser can be avoided through high frequency induction heating in the remelting process; and refining grains of the ceramic layer through ultrasonic vibration to obtain a densely-arranged columnar crystal. Due to the introduction of the two high frequency induction heating and ultrasonic vibration assisted processes, the ceramic coating with a densely-arranged columnar crystal structure can be obtained, the laser remolten ceramic coating is fewer in cracks as well as uniform and dense in columnar crystal tissues, and the width of the densely-arranged columnar crystal is 1-5mu m.

Description

technical field [0001] The invention belongs to the technical field of laser processing, and in particular relates to a preparation process of a close-packed columnar crystal ceramic coating based on laser remelting technology. Background technique [0002] At present, the biggest problem facing the preparation of thermal barrier coatings in my country is premature peeling of the coating. A large number of studies have shown that there are three main reasons for the peeling of the coating: thermally grown oxide (TGO, the main component of which is Al at the interface between the ceramic layer and the bonding layer) 2 o 3 ) formation and growth; the interface bonding strength is insufficient; the thermal expansion coefficient of the ceramic layer and the substrate does not match. On the one hand, this is related to the properties of the coating material, and on the other hand, it is also closely related to the coating structure and its preparation method. [0003] The ceram...

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Problems solved by technology

[0003] The ceramic layer is the core of the thermal barrier coating system, but due to the inherent properties of the material, its thermal expansion coefficient is smaller than that of the substrate and the bonding layer, and its quality is brittle. It is very easy to cause thermal expansion coefficient mismatch under the condition of thermal strain The ceramic layer peels off. In addition, there are generally micro-gap in the top ceramic layer. At high temperature, oxygen atoms and corrosive impurities in the gas (SO 2 ,V 2 o 5 ) is easy to diffuse into the bonding layer, causing the bonding layer to oxidize and expand or corrode and deteriorate, eventually leading to the peeling and failure of the coating. Finally, the bonding force between the ceramic layer and the bonding layer also has a great impact on the life of the thermal barrier coating. The interface formed by spraying is mainly a mechanical structure. This combination method has low bonding force, and the working reliability is reduced in the harsh environment of high temperature and high pressure.

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