阅读说明：本技术 一种基于超声振动辅助激光改性自愈合热障涂层的制备方法 (Preparation method of self-healing thermal barrier coating based on ultrasonic vibration assisted laser modification ) 是由 张盼盼 孙磊 姚建华 张群莉 姚喆赫 于 2021-09-07 设计创作，主要内容包括：一种基于超声振动辅助激光改性自愈合热障涂层的制备方法：将含有自愈合颗粒的混合粉末均匀铺在热障涂层试样上,将试样放在超声振动台上,利用1kW激光制造系统进行激光改性表面处理,获得自愈合热障涂层；本发明利用超声振动辅助激光合金化技术让自愈合颗粒掺杂于热障涂层,并使自愈合颗粒均匀分布在改性层中；在热障涂层热服役过程中,利用自愈合颗粒在高温情况下被氧化生成氧化物而产生体积膨胀从而填充裂纹,实现裂纹的自愈合效应,进而提升热障涂层的抗热震性能与热腐蚀性能；采用本发明得到的激光改性热障涂层,可明显提升高端装备关键热端部件在高温恶劣服役环境下的适应能力和服役寿命。(A preparation method of a self-healing thermal barrier coating based on ultrasonic vibration assisted laser modification comprises the following steps: uniformly paving mixed powder containing self-healing particles on a thermal barrier coating sample, placing the sample on an ultrasonic vibration table, and performing laser modification surface treatment by using a 1kW laser manufacturing system to obtain a self-healing thermal barrier coating; the self-healing particles are doped in the thermal barrier coating by utilizing an ultrasonic vibration assisted laser alloying technology, and are uniformly distributed in the modified layer; in the thermal service process of the thermal barrier coating, the self-healing particles are oxidized at high temperature to generate oxides, and volume expansion is generated to fill cracks, so that the self-healing effect of the cracks is realized, and the thermal shock resistance and the hot corrosion resistance of the thermal barrier coating are further improved; the laser modified thermal barrier coating obtained by the invention can obviously improve the adaptability and service life of the key hot end component of high-end equipment in a high-temperature severe service environment.)

1. A preparation method of a self-healing thermal barrier coating based on ultrasonic vibration assisted laser modification is characterized by comprising the following steps:

uniformly paving mixed powder containing self-healing particles on a thermal barrier coating sample, placing the sample on an ultrasonic vibration table, and performing laser modification surface treatment by using a 1kW laser manufacturing system to obtain a self-healing thermal barrier coating;

TiAl is selected as the self-healing particles₃(ii) a The mixed powder containing the self-healing particles comprises the following components: 5-20% of TiAl₃The balance is CYSZ;

when the laser modified surface treatment is carried out, a plurality of laser paths are punched on the surface of a thermal barrier coating sample, the repetition rate of each laser path is 0-30%, the laser power is 100-400W, the scanning speed is 10-40 mm/s, the diameter of a light spot is 1-2 mm, and the ultrasonic vibration auxiliary frequency is 50-4500W.

2. The method for preparing the self-healing thermal barrier coating through ultrasonic vibration assisted laser modification according to claim 1, wherein the mixed powder containing the self-healing particles is laid on a thermal barrier coating sample to a thickness of 0.3-1 mm.

Technical Field

The invention relates to a laser surface treatment method, in particular to a preparation method of a self-healing thermal barrier coating based on ultrasonic vibration assisted laser modification

Background

With the development of science and technology, the aeroengine has extremely wide application, the working parts in the combustion system of the aeroengine can bear higher temperature and higher stress, the parts can be damaged, and in order to prolong the service life of the parts, the thermal barrier coating is applied to the hot end parts of the engine and the gas turbine. A commonly used thermal barrier coating consists of a Thermally insulating ceramic top layer, an oxidation resistant bond coat, Thermally Grown Oxides (TGO) formed by oxidation of the bond coat, and a superalloy substrate. The ceramic layer is mostly prepared by Spraying 7-8% YSZ powder by Air Plasma Spraying (APS) or Electron Beam Physical Vapor Deposition (EB-PVD), and has a thickness of 200-400 μ M, and the bonding layer is prepared by Spraying MCrAlY (M can be Ni, Co or a mixture of Ni and Co) powder by low-pressure Plasma Spraying, vacuum Plasma Spraying or supersonic flame Spraying, and has a thickness of 50-150 μ M. However, cracks and holes are inevitably generated in the thermal barrier coating in the preparation process, so that the bonding layer is oxidized due to the penetration of oxygen under the high-temperature condition, the TGO layer is thickened, the accumulated TGO stress promotes the initiation and the propagation of horizontal cracks, and finally the horizontal cracks are connected with the vertical cracks to cause the spalling failure of the coating.

Self-healing means that once a material generates a defect in the working process, the material has the self-recovery capability without external action. The self-healing method is to utilize proper material design and preparation process to enable the material to have self-healing performance, so that cracks in the material can be obviously reduced, and the material performance is improved. The self-healing effect of the invention is realized by utilizing the self-healing particles to generate oxidation under the condition of high-temperature service to generate volume expansion so as to fill cracks in the coating.

The self-healing particles are doped in the thermal barrier coating by adopting a laser alloying technology, so that the oxidation resistance and the thermal shock resistance of the thermal barrier coating under high-temperature service can be effectively improved, and the service life of the thermal barrier coating is prolonged. The method mainly utilizes high-energy laser beams to rapidly melt and fuse the self-healing material on the surface layer of the ceramic layer, so that a surface alloying layer with required depth and chemical components is formed on the surface layer of a matrix, and self-healing particles are uniformly distributed in the alloying layer. In the thermal cycle service process of the thermal barrier coating, at the early stage of thermal cycle, the laser modification of the reticular cracks in the thermal barrier coating and the vertical cracks which do not penetrate through the coating is beneficial to improving the strain tolerance of the coating and prolonging the service life of the coating; however, in the later stage of thermal service, because the TGO layer is too thick, horizontal cracks are initiated and expanded, the coating is peeled off due to the connection of the horizontal cracks and the vertical cracks, and the self-healing particles are oxidized in the thermal service process to generate oxidation products, so that the cracks are filled by volume expansion, the self-healing of the cracks is realized, and the peeling of the coating is slowed down.

At present, there is a clear open literature describing laser modified thermal barrier coatings.

Disclosure of Invention

In order to reduce and eliminate cracks and holes in a thermal barrier coating prepared by Atmospheric Plasma Spraying (APS), a self-healing method for modifying the cracks of the thermal barrier coating by using ultrasonic vibration assisted laser is designed, and the method belongs to the surface processing technology. The thermal barrier coating described in the present invention comprises a ceramic top layer, a bond coat and a superalloy substrate. The self-healing particles are melted in the thermal barrier coating through ultrasonic vibration assisted laser modification, and in the subsequent high-temperature service process, the self-healing particles are subjected to oxidation reaction to generate oxides to generate volume expansion so as to fill cracks, so that the cracks and holes in the thermal barrier coating are reduced and even disappear.

Meanwhile, as the laser modified thermal barrier coating has longitudinal cracks which do not penetrate through the coating, the vertical cracks of the thermal barrier coating can improve the strain tolerance of the coating and prolong the service life in the early stage of thermal cycle. And in the later stage of thermal service, the self-healing particles are oxidized to generate volume expansion to fill cracks, so that the self-healing effect of the cracks is realized, oxygen can be prevented from permeating into the bonding layer, further thickening of thermally grown oxides and generation of spinel oxides are avoided, cracking, stripping and failure of the coating are delayed, and meanwhile, the thermal shock resistance of the coating is improved.

The technical scheme of the invention is as follows:

a preparation method of a self-healing thermal barrier coating based on ultrasonic vibration assisted laser modification comprises the following steps:

uniformly paving mixed powder containing self-healing particles on a thermal barrier coating sample, placing the sample on an ultrasonic vibration table, and performing laser modification surface treatment by using a 1kW laser manufacturing system to obtain a self-healing thermal barrier coating;

TiAl is selected as the self-healing particles₃(ii) a The mixed powder containing the self-healing particles comprises the following components: 5-20% of TiAl₃The balance of CYSZ (cerium oxide yttria partially stabilized zirconia, ZrO)₂-24wt％CeO₂-2.4wt％Y₂O₃) (ii) a The laying thickness of the mixed powder on the thermal barrier coating sample is 0.3-1 mm;

when the laser modified surface treatment is carried out, a plurality of (for example, 6-12) laser paths are punched on the surface of a thermal barrier coating sample, the repetition rate of each laser path is 0-30%, the laser power is 100-400W, the scanning speed is 10-40 mm/s, the diameter of a light spot is 1-2 mm, and the ultrasonic vibration auxiliary frequency is 50-4500W.

The thickness of the self-healing thermal barrier coating obtained by laser modification is 100-300 mu m, and the interior of the self-healing thermal barrier coating contains longitudinal cracks which do not penetrate through the modification layer. The laser modification treatment of the invention can utilize the self-healing particles to generate oxidation reaction and generate volume expansion in the high-temperature thermal service process of the thermal barrier coating so as to fill cracks, further reduce the cracks and pores in the thermal barrier coating, and improve the high-temperature oxidation resistance and thermal shock resistance of the thermal barrier coating, thereby being used for surface protection of key hot end parts of high-end equipment.

The method for evaluating the performance of the coating comprises the following steps:

and carrying out a thermal shock experiment on the original thermal barrier coating and the laser modified thermal barrier coating. Placing the unmodified thermal barrier coating and the laser modified thermal barrier coating in a high-temperature box furnace, preserving heat for 5min at 1000 ℃, then taking out the thermal barrier coating, placing the thermal barrier coating and the laser modified thermal barrier coating in deionized water, rapidly cooling to room temperature (25 ℃), drying by using a blower, and repeating the process (the whole heat treatment process does not need vacuum). And the coating surface changes were observed and recorded using a high power camera. The thermal cycle times for both thermal barrier coatings were recorded with a coating surface spallation rate of 20% as the criterion for coating failure.

The invention has the following beneficial effects:

because in the process of atmospheric plasma spraying, molten or semi-molten particles are deposited on the surface of the substrate, and the sprayed layer is a layered structure formed by stacking countless deformed particles, holes or cracks exist in the coating, and the thermal shock resistance and the hot corrosion resistance are poor. The self-healing particles are doped in the thermal barrier coating by utilizing the ultrasonic vibration assisted laser alloying technology and are uniformly distributed in the modified layer. In the thermal service process of the thermal barrier coating, the self-healing particles are oxidized at high temperature to generate oxides, and volume expansion is generated to fill cracks, so that the self-healing effect of the cracks is realized, and the thermal shock resistance and the thermal corrosion resistance of the thermal barrier coating are further improved. The laser modified thermal barrier coating obtained by the invention can obviously improve the adaptability and service life of the key hot end component of high-end equipment in a high-temperature severe service environment.

Drawings

FIG. 1 is a surface micro-topography of an original thermal barrier coating.

Fig. 2 is a microscopic topography of the original thermal barrier coating cross-section.

FIG. 3 is a surface micro-topography of a laser modified thermal barrier coating in example 1 of the present invention.

FIG. 4 is a cross-sectional micro-topography of a laser modified thermal barrier coating in example 1 of the present invention.

FIG. 5 shows the cross-sectional micro-morphology of the laser-modified thermal barrier coating before the thermal shock test in example 1 of the present invention.

FIG. 6 is a cross-sectional micro-topography of a laser modified thermal barrier coating after a thermal shock test in example 1 of the present invention.

Detailed Description

The invention is further described below by means of specific examples, without the scope of protection of the invention being limited thereto.

TiAl used in the examples₃The particle size is mainly distributed within 15-150 mu m; the CYSZ is provided by Jiangxi Ganzhou science Ying structural ceramics, Inc., and the particle size distribution is 15-120 mu m.

Example one

1) Preparing a thermal barrier coating on a nickel-based high-temperature alloy substrate, wherein the thermal barrier coating comprises a ceramic layer and a bonding layer; the bond coat was prepared by supersonic flame spraying with a powder of NiCrAlY, the bond coat thickness being about 100 μm.

2) On the prepared bond coat, a ceramic layer was prepared by Atmospheric Plasma Spraying (APS), the powder being 7% yttria partially stabilized zirconia (7YSZ), the ceramic layer having a thickness of about 300 μm.

3) And carrying out ultrasonic cleaning on the prepared thermal barrier coating to remove surface stains and impurities.

4) 5% of TiAl₃The + CYSZ self-healing powder is uniformly paved on a thermal barrier coating sample, the paving thickness is about 0.3mm, a ceramic layer of the thermal barrier coating is modified by utilizing a laser modification technology (laser alloying), the selected equipment is a 1kW flexible laser manufacturing system and ultrasonic vibration auxiliary equipment, laser sweeps 5 paths on the surface of the ceramic layer, and the repetition rate is 0%. In the laser process parameters, the laser power is 200W, the laser scanning speed is 15mm/s, the laser spot size diameter is 1mm, the ultrasonic vibration auxiliary frequency is 2000W, and the thickness of the obtained laser modified layer is about 252 μm.

5) The thermal shock test is carried out on the unmodified thermal barrier coating and the laser modified thermal barrier coating, the thermal cycle life of the unmodified thermal barrier coating is 200 times, the thermal cycle life of the laser modified thermal barrier coating is 610 times, the thermal shock resistance of the laser modified thermal barrier coating is 3.05 times of that of the unmodified thermal barrier coating, and the thermal shock resistance of the thermal barrier coating can be obviously improved by laser modification treatment.

The surface microscopic morphology of the treated thermal barrier coating is shown in FIG. 3, and the observed cross-sectional morphology is shown in FIG. 4.

Compared with the graph shown in fig. 1 and fig. 3, the surface of the original thermal barrier coating is rough, and part of unmelted particles, air holes and microcracks are distributed, after laser modification, the surface of the thermal barrier coating is smooth and is distributed with network cracks, and the coating is more compact.

Compared with fig. 2 and 4, the original thermal barrier coating has more pores and microcracks, the coating is of a layered structure, and the cross section of the thermal barrier coating after laser modification treatment is more compact and has longitudinal cracks which do not penetrate through.

Comparing fig. 5 and fig. 6, comparing the cross-sectional morphology of the laser modified thermal barrier coating before and after the thermal shock test, the vertical cracks of the thermal barrier coating after the thermal shock test are obviously reduced, and the thermal barrier coating and the surface of the unmodified area are in the same horizontal plane, so that the integrity of the thermal barrier coating is maintained, and the good crack self-healing capability is realized.

5% TiAl laser doping assisted by ultrasonic vibration₃The + CYSZ self-healing powder is arranged in the thermal barrier coating, and self-healing particles are oxidized in the high-temperature thermal service process to generate volume expansion to fill cracks, so that the self-healing effect of the cracks is realized, and the thermal shock resistance of the thermal barrier coating can be obviously improved.

Example two

1) Preparing a thermal barrier coating on a nickel-based high-temperature alloy substrate, wherein the thermal barrier coating comprises a ceramic layer and a bonding layer; the bond coat was prepared using Atmospheric Plasma Spray (APS), powder NiCrAlY, and a bond coat thickness of approximately 100 μm.

2) On the prepared bond coat, a ceramic layer was prepared by Atmospheric Plasma Spraying (APS), the powder being 7% yttria partially stabilized zirconia (7YSZ), the ceramic layer having a thickness of about 300 μm.

3) And carrying out ultrasonic cleaning on the prepared thermal barrier coating to remove surface stains and impurities.

4) 10% of TiAl₃The + CYSZ self-healing powder is uniformly spread on the surface of the thermal barrier coating sample, the spread powder thickness is about 0.4mm, and the laser modification technology (laser alloying) is adopted to feed the ceramic layer of the thermal barrier coatingModifying, wherein the adopted equipment is a 1kW flexible laser manufacturing system, and the laser sweeps 5 paths on the surface of the ceramic layer, and the repetition rate is 20%. In the laser process parameters, the laser power is 300W, the laser scanning speed is 25mm/s, the laser spot size is 1.5mm, the laser modification is assisted by a laser ultrasonic auxiliary vibration system, the ultrasonic vibration auxiliary frequency is 3000W, and the thickness of the obtained laser modified layer is about 200 μm.

5) The thermal shock test is carried out on the unmodified thermal barrier coating and the laser modified thermal barrier coating, the thermal cycle life of the unmodified thermal barrier coating is about 200 times, the thermal cycle life of the laser modified thermal barrier coating is about 720 times, the thermal shock resistance of the laser modified thermal barrier coating is about 3.6 times of that of the unmodified thermal barrier coating, and the thermal shock resistance of the thermal barrier coating can be obviously improved by laser modification treatment.

EXAMPLE III

1) Preparing a thermal barrier coating on a nickel-based high-temperature alloy substrate, wherein the thermal barrier coating comprises a ceramic layer and a bonding layer; the bond coat was prepared by atmospheric plasma spraying with a powder of NiCrAlY and a bond coat thickness of about 100 μm.

2) On the prepared bond coat, a ceramic layer was prepared by Atmospheric Plasma Spraying (APS), the powder being 7% yttria partially stabilized zirconia (7YSZ), the ceramic layer having a thickness of about 300 μm.

3) And carrying out ultrasonic cleaning on the prepared thermal barrier coating to remove surface stains and impurities.

4) 15% of TiAl₃The + CYSZ self-healing powder is uniformly paved on the surface of a thermal barrier coating sample, the paving thickness is about 0.5mm, a ceramic layer on the surface of the thermal barrier coating is modified by adopting a laser modification technology (laser alloying), the adopted equipment is a 1kW flexible laser manufacturing system, laser sweeps 5 paths on the surface of the ceramic layer, and the repetition rate is 30%. In the laser process parameters, the laser power is 400W, the laser scanning speed is 35mm/s, the laser spot size is 2mm, the laser modification is assisted by a laser ultrasonic auxiliary vibration system, the ultrasonic vibration auxiliary frequency is 4000W, and the thickness of the obtained laser modified layer is about 230 μm.

5) After a thermal shock test, the thermal cycle life of the unmodified thermal barrier coating is 200 times, the thermal cycle life of the laser modified thermal barrier coating is 820 times, the thermal shock resistance of the laser modified thermal barrier coating is about 4.1 times of that of the unmodified thermal barrier coating, and the thermal shock resistance of the thermal barrier coating can be obviously improved by laser modification treatment.

The technical scheme disclosed and proposed by the invention can realize the purpose of experiments by appropriately changing the experimental conditions such as the conditional route and the like by referring to the contents of the text for the technicians in the field. Although the method and the preparation technique of the present invention have been described by way of preferred embodiments, the technical solutions described in the foregoing embodiments can be modified. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present invention are within the protection scope of the present invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be included within the spirit, scope and content of the invention.