阅读说明：本技术 抗剥落复合结构隔热涂层的制备方法 (Preparation method of anti-stripping composite structure heat insulation coating ) 是由 杨二娟 刘福广 李勇 王博 米紫昊 刘刚 王艳松 韩天鹏 于 2020-07-10 设计创作，主要内容包括：一种抗剥落复合结构隔热涂层的制备方法,小粒径熔炼破碎陶瓷粉末和大粒径纳米团聚结构陶瓷粉末按比例混合制备而成,涂层制备前,基材表面喷砂后,预制金属层或者金属陶瓷混合层作为隔热涂层的打底层；其中小粒径熔炼破碎陶瓷粉末制备过程中完全融化沉积形成常规层状结构涂层；团聚粉末纳米颗粒之间导热较差,因此,大粒径纳米团聚结构陶瓷粉末在涂层制备过程中为半融化态,最终保留在了层状结构涂层中；从而获得层状结构与残余团聚粉末结合的复合结构。在常规层状结构陶瓷层中引入半熔化团聚烧结粉末,通过半熔化团聚烧结粉末对层状结构的钉扎作用起到层间裂纹止裂的效果,最终实现陶瓷层抗剥落能力的提高。(A preparation method of an anti-stripping composite structure heat insulation coating is characterized in that small-particle size melting broken ceramic powder and large-particle size nano-agglomeration structure ceramic powder are mixed in proportion to prepare the anti-stripping composite structure heat insulation coating, before the coating is prepared, after sand blasting is carried out on the surface of a base material, a metal layer or a metal ceramic mixing layer is prefabricated to serve as a bottom layer of the heat insulation coating; wherein, the conventional layered structure coating is formed by complete melting and deposition in the preparation process of the small and medium grain size melting and crushing ceramic powder; the heat conduction among the agglomerated powder nanoparticles is poor, so that the large-particle-size nano agglomerated structure ceramic powder is in a semi-molten state in the coating preparation process and is finally retained in the layered structure coating; thereby obtaining a composite structure in which the layered structure is combined with the residual agglomerated powder. Semi-melting agglomerated sintering powder is introduced into a conventional laminated ceramic layer, and the semi-melting agglomerated sintering powder plays a role in interlayer crack arrest on the pinning effect of the laminated structure, so that the improvement of the anti-stripping capability of the ceramic layer is finally realized.)

1. A preparation method of an anti-stripping composite structure heat insulation coating is characterized by comprising the following steps: the method comprises the following steps:

step 1: uniformly mixing small-particle size smelted and crushed ceramic powder and large-particle size nano-agglomerated structure ceramic powder in proportion;

step 2: before the coating is prepared, after sand blasting is carried out on the surface of a base material, a metal layer or a metal ceramic mixing layer is prefabricated to be used as a priming layer of the heat insulation coating;

and step 3: spraying the mixed powder in the step 1 on the surface of the base material with the pre-prepared priming layer in the step 2;

in the spraying process, the small-particle size melting and crushing ceramic powder is completely melted and deposited to form a layered structure coating in the spraying process; because of the heat conduction difference among the agglomerated powder nanoparticles, the ceramic powder with the large-particle-size nano agglomerated structure is in a semi-molten state in the spraying process and is finally retained in the laminated structure coating, so that a composite structure combining the laminated structure and the residual agglomerated powder is obtained; semi-melting agglomerated sintering powder is introduced into the ceramic layer with the layered structure, and the semi-melting agglomerated sintering powder plays a role in preventing cracks between layers by pinning the layered structure, so that the anti-stripping capability of the ceramic layer is improved finally.

2. The method of making a spallation resistant composite structural thermal barrier coating of claim 1, wherein: the weight ratio of the small-particle size melting and crushing ceramic powder to the large-particle size nano agglomerated structure ceramic powder is 8: 2.

3. The method of making a spallation resistant composite structural thermal barrier coating of claim 1, wherein: and mechanically mixing the small-particle size melting and crushing ceramic powder and the large-particle size nano agglomerated structure ceramic powder.

4. The method of making a spallation resistant composite structural thermal barrier coating of claim 1, wherein: the particle size of the small-particle size smelting and crushing ceramic powder is 10-30 mu m; the grain diameter of the ceramic powder with the large-grain diameter nano-aggregation structure is 45-75 mu m.

5. The method of making a spallation resistant composite structural thermal barrier coating of claim 1, wherein: the small-particle size melting and crushing ceramic powder and the large-particle size nano agglomerated structure ceramic powder are yttria-stabilized zirconia powder or alumina powder.

6. The method of making a spallation resistant composite structural thermal barrier coating of claim 1, wherein: the spraying adopts atmospheric plasma spraying or high-energy ion beam spraying.

Technical Field

The invention belongs to the technical field of surface engineering, and particularly relates to a preparation method of an anti-stripping composite structure heat-insulating coating.

Background

With frequent peak regulation and even deep peak regulation of the unit, the problem of transverse cracking of the water-cooled wall of the supercritical (super) critical boiler is gradually aggravated. The main reason for the transverse cracking of the water wall of the supercritical (super) critical boiler is the thermal corrosion fatigue cracking of the fire-facing side of the water wall tube under the combined action of alternating thermal stress and high-temperature corrosion medium. The water wall is transversely cracked, so that large-area tube replacement in the unit overhauling process is caused, overhauling cost is greatly increased, leakage is easy to occur, unplanned shutdown is caused, and the water wall becomes an important hidden danger influencing the long-term safe operation of the supercritical (supercritical) unit.

The main treatment measure of the transverse cracks of the water-cooled wall of the thermal power generating unit in China is that the thermal power generating unit is inspected when the thermal power generating unit stops, and once the cracks are found, a new pipe is replaced immediately. Aiming at the important reason that the temperature change causes the transverse cracking of the water wall tube, partial power plants try a conventional thermal barrier coating heat insulation strategy, and a MCrAlY/YSZ thermal barrier coating with a conventional structure is prepared on the surface of the water wall by adopting supersonic flame spraying (HVOF) and Atmospheric Plasma Spraying (APS) so as to weaken the stress amplitude caused by the surface temperature change and further prevent or delay the generation and the expansion of cracks. Practice proves that the thermal barrier coating of the conventional layered structure is peeled off in a short-term service due to extremely high temperature gradient and surface temperature fluctuation inside and outside the water-cooled wall of the ultra-supercritical coal-fired boiler.

Disclosure of Invention

In order to solve the above problems, the present invention aims to provide a method for preparing an anti-spalling composite structure thermal insulation coating, wherein the prepared coating slows down the stress amplitude caused by the temperature change of the surface of the water wall of the supercritical (super) critical unit, and prevents or delays the generation and propagation of the transverse cracks of the water wall.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of an anti-stripping composite structure heat insulation coating comprises the following steps:

step 1: uniformly mixing small-particle size smelted and crushed ceramic powder and large-particle size nano-agglomerated structure ceramic powder in proportion;

step 2: before the coating is prepared, after sand blasting is carried out on the surface of a base material, a metal layer or a metal ceramic mixing layer is prefabricated to be used as a priming layer of the heat insulation coating;

and step 3: spraying the mixed powder in the step 1 on the surface of the base material with the pre-prepared priming layer in the step 2;

in the spraying process, the small-particle size smelted and crushed ceramic powder is completely melted and deposited in the spraying process to form a layered structure coating; because of the heat conduction difference among the agglomerated powder nanoparticles, the ceramic powder with the large-particle-size nano agglomerated structure is in a semi-molten state in the spraying process and is finally retained in the laminated structure coating, so that a composite structure combining the laminated structure and the residual agglomerated powder is obtained; semi-melting agglomerated sintering powder is introduced into the ceramic layer with the layered structure, and the semi-melting agglomerated sintering powder plays a role in preventing cracks between layers by pinning the layered structure, so that the anti-stripping capability of the ceramic layer is improved finally.

The weight ratio of the small-particle size melting and crushing ceramic powder to the large-particle size nano agglomerated structure ceramic powder is 8: 2.

And mechanically mixing the small-particle size melting and crushing ceramic powder and the large-particle size nano agglomerated structure ceramic powder.

The particle size of the small-particle size smelting and crushing ceramic powder is 10-30 mu m; the grain diameter of the ceramic powder with the large-grain diameter nano-aggregation structure is about 45-75 mu m.

The small-particle size melting and crushing ceramic powder and the large-particle size nano agglomerated structure ceramic powder can be yttria-stabilized zirconia, alumina and the like;

the spraying of the composite structure heat insulation coating can be selected from atmospheric plasma spraying, high-energy ion beam spraying and the like.

The invention has the following advantages:

1) the coating composite structure is realized by different powder structures, and the process is simple.

2) Compared with the laminated structure coating, the elastic modulus and the thermal conductivity of the composite structure ceramic coating are not obviously changed, the average service life of the coating with 20% of stripping is prolonged from 19.7 times to 72.1, and the stripping resistance is improved by about 2.6 times.

Drawings

FIG. 1 is a schematic structural view of an anti-spalling composite thermal barrier coating of the present invention.

Fig. 2a shows the appearance of an anti-peeling composite structure coating prepared by atmospheric plasma spraying according to an embodiment of the present invention.

Fig. 2b is an enlarged view of the porous region of fig. 2 a.

FIG. 3 is a graph showing the thermal conductivity of an anti-spallation composite structure coating and a traditional layered thermal barrier coating prepared by atmospheric plasma spraying according to an embodiment of the invention.

FIG. 4 shows the times of peel resistance of the anti-peel composite structure coating and the conventional layered thermal barrier coating prepared by atmospheric plasma spraying according to the embodiment of the present invention.

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples.

The invention relates to a preparation method of an anti-stripping composite structure heat insulation coating, which comprises the following steps:

step 1: mechanically mixing small-particle size smelting crushed ceramic powder and large-particle size nano-agglomerated structure ceramic powder uniformly according to the weight ratio of 8: 2;

step 2: before the coating is prepared, after sand blasting is carried out on the surface of a base material, a metal layer or a metal ceramic mixing layer is prefabricated to be used as a priming layer of the composite structure heat insulation coating;

and step 3: and (3) spraying the mixed powder in the step (1) on the surface of the base material with the pre-prepared priming layer in the step (2) by adopting methods such as atmospheric plasma spraying, high-energy ion beam spraying and the like, wherein the thickness of the spraying coating is 280-320 mu m. The composite structure thermal barrier coating structure is shown in fig. 1, from which it can be seen that: two typical features are presented in the ceramic layer, there are porous regions in the relatively dense texture as shown in fig. 1, where the porous regions are formed by unmelted or semi-melted large particle size nano-agglomerated sintered powder remaining in the coating. Semi-melting agglomerated sintering powder is introduced into the ceramic layer with the layered structure, and the semi-melting agglomerated sintering powder plays a role in preventing cracks between layers by pinning the layered structure, so that the anti-stripping capability of the ceramic layer is improved finally.