A nano/columnar-like mixed structure thermal barrier coating and its preparation method

Abstract

The invention relates to a nanometer / columnar-like crystal mixing structure thermal barrier coating and a preparation method thereof. The mixing structure thermal barrier coating is a nanometer / columnar-like crystal mixing structure coating, and comprises a substrate, a metal bonding layer and a ceramic layer, wherein the metal bonding layer and the ceramic layer are sequentially coated on the substrate, the ceramic layer comprises unmelted nanoparticles, nanometer pores, nanometer crystal and ultrafine crystal, and has cracks perpendicular to the substrate, and the cracks form the columnar-like crystal structure. The mixing structure thermal barrier coating preparation method comprises powder selection, a pretreatment step, a substrate pretreatment step, a metal bonding layer preparation step, and a 6-8% YSZ ceramic layer preparation step. The coating disclosed by the present invention has characteristics of high strain tolerance, excellent thermal insulation performance, high bonding strength, high thermal cycle life, and high thermal shock life, such that the thermal barrier coating has a good comprehensive performance.

Description

technical field [0001] The present invention relates to a method for preparing a novel hybrid structure thermal barrier coating, in particular to a method of spraying nanometer YSZ powder using a conventional plasma spraying process to prepare a nano / columnar crystal mixed structure thermal barrier coating with higher strain tolerance and good comprehensive performance. barrier coating method. Background technique [0002] Thermal Barrier Coating (TBC) is a high-temperature structural material surface protection technology that uses the excellent high-temperature resistance, heat insulation, and corrosion resistance of ceramic materials to combine ceramics and metal substrates in the form of coatings. It is composed of a ceramic surface layer with high conductivity and a metal bonding layer with good thermal expansion coefficient matching with the metal substrate and ceramic surface layer. The use of thermal barrier coatings will significantly increase the operating tempera...

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Problems solved by technology

[0006] There are more reports and applications of micron powder sprayed columnar crystal structure coatings in the world, such as the U.S. Patent No. "US5558992" and the technology disclosed in the European Patent No. "EP1281788A1", but they all use denser or Surface melted smelting crushing, sintering crushing, HOSP (agglomerated into hollow powder and then plasma spheroidized) powder to prepare the coating, although it is easier to obtain a vertical crack structure similar to columnar crystals, but the thermal insulation performance of the coating is relatively reduced (thermal Conductivity 1.2~1.6W / m K), and there are many transverse cracks around the columnar crystals (cracks between layers parallel to the direction of the matrix)

The preparation method disclosed in the Chinese invention patent application with the application number "200910237548" and the title "multi-element rare earth oxide-doped zirconia thermal barrier coating with network crack structure and its preparation method" uses multi-element rare earth oxide The proportion of transverse cracks in the coating prepared by modified powder (solid-phase synthesized micron powder before agglomeration) is 10-50%, which will lead to cracks along the transverse cracks in the coating during service, and cannot make full use of the advantages of the columnar crystal structure , which affects the further improvement of the reliability and service life of the coating; at the same time, there are certain requirements for the thickness of some columnar crystal structure coatings in the application process, which usually needs to reach more than 0.5mm

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