Control method for thermal barrier coating porosity

Abstract

The invention discloses a control method for thermal barrier coating porosity. Through adjusting plasma spraying process parameters, online measurement is performed for spraying particles of different embodiments by using Spray Watch2i to obtain particle flying speeds and particle surface temperatures under different process parameters; the particle flying speeds and surface temperatures are grouped to three areas of high-temperature and high-speed, medium-temperature and medium-speed and low-temperature and low-speed; the three areas are sprayed to obtain coating layers; and the coating porosity is obtained by performing scanning electron microscope measurement; the quantitative relation between the particle flying speeds and surface temperatures and the coating porosity is determined; and the spraying process parameters are adjusted to realize effective control of coating microstructures.

Description

technical field [0001] The invention relates to a method for controlling the microstructure of thermal barrier coatings in turbine engines and large gas turbines. Background technique [0002] Thermal barrier coatings (Thermal barrier coatings, TBCs) are a functional coating applied on the surface of a metal substrate to reduce the temperature of the substrate to ensure its normal use under high temperature conditions. This coating is currently used in gas turbine engines It is widely used on the hot end parts in the field. Its design idea is mainly to use the advantages of high melting point, low thermal conductivity and high toughness of metal materials to form a coating system (multi-layer structure) to meet the requirements of high temperature use. However, the thermal barrier coating system composed of "ceramic coating / alloy transition layer (bonding layer) / superalloy substrate" is due to the mismatch in physical, chemical and mechanical properties, as well as the comp...

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Problems solved by technology

However, the thermal barrier coating system composed of "ceramic coating / alloy transition layer (bonding layer) / superalloy substrate" is due to the mismatch in physical, chemical and mechanical properties, as well as the complexity and complexity of the process during processing. The harsh high temperature and corrosive environment in subsequent use make it difficult for thermal barrier coatings to meet the rapidly developing national defense technology (such as the high efficiency, high stability, The demand for high-power aero-engines and heavy-duty gas turbines required by large ships)

In addition, there is still a disconnect between theory and practice in terms of the supporting research on the materials, design, and process of thermal barrier coatings and the consistency and stability requirements of coating microstructure and quality control at the production level, making thermal barrier coatings There is still a big gap between the preparation process, service life, production cost and batch stability and the international advanced level, which seriously hinders the development and application of thermal barrier coatings in the cutting-edge fields of national defense.

[0003] For plasma spraying, due to the many process parameters involved, it is difficult to ensure the stability of the coating quality during the coating deposition process, resulting in the same batch of deposited coatings often have great differences in structure

At present, engineers often rely on the adjustment of current, voltage or gas parameters to control the properties of the plasma, and conduct comparative tests in combination with sample metallographic standards and physical and chemical properties to optimize and control the coating structure. This indirect method not only requires a lot of work , long period, and often need to repeat many tests, it is difficult to meet the requirements of modern high-performance coating preparation process and structural quality control

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