CN113929474B

CN113929474B - Particulate matter for thermal barrier coating, preparation method of particulate matter, thermal barrier coating and engine

Info

Publication number: CN113929474B
Application number: CN202111536457.0A
Authority: CN
Inventors: 张鑫; 原慷; 彭浩然; 卢晓亮; 颜正; 庞小肖; 贾芳
Original assignee: Bgrimm Advanced Materials Science & Technology Co ltd; BGRIMM Technology Group Co Ltd
Current assignee: Bgrimm Advanced Materials Science & Technology Co ltd; BGRIMM Technology Group Co Ltd
Priority date: 2021-12-16
Filing date: 2021-12-16
Publication date: 2022-03-04
Anticipated expiration: 2041-12-16
Also published as: CN113929474A

Abstract

The application provides a particulate matter for a thermal barrier coating, a preparation method of the particulate matter, the thermal barrier coating and an engine, and relates to the field of new materials. Particulate matter for a thermal barrier coating comprising a shell and an inner core; the porosity of the surface of the shell is less than or equal to 5%; the inner core is provided with first closed pores with the pore diameter of 1-5 mu m, first skeleton microparticles are arranged between the first closed pores, and the particle size of the first skeleton microparticles is 0.1-2 mu m. Thermal barrier coating obtained by plasma flame jet deposition using particulate matter for the thermal barrier coating. An engine comprising a thermal barrier coating. The particulate matter for the thermal barrier coating and the thermal barrier coating have good high-temperature-resistant thermal cycle performance.

Description

Particulate matter for thermal barrier coating, preparation method of particulate matter, thermal barrier coating and engine

Technical Field

The application relates to the field of new materials, in particular to a particulate matter for a thermal barrier coating, a preparation method of the particulate matter, the thermal barrier coating and an engine.

Background

With the increasing inlet temperature of aero-engine combustors and turbines, especially the gas temperature of the most advanced engine design exceeds 1800 ℃, the surface temperature of parts and components may reach 1500 ℃, which is an ultra-high temperature, and this presents a new challenge for ceramic thermal insulation coatings. The development of high temperature resistant thermal insulation coatings requires, on the one hand, the design of new material systems and, on the other hand, the optimization of microstructures. At present, the design of a high-temperature resistant ceramic material system is infinite, but the structural design of a high-temperature resistant heat insulation layer is rarely reported.

The problem to be solved is to prepare the thermal barrier coating with good high-temperature thermal cycle performance by using any material.

Disclosure of Invention

The present application aims to provide a particulate matter for a thermal barrier coating, a method for preparing the same, a thermal barrier coating and an engine, so as to solve the above problems.

In order to achieve the purpose, the following technical scheme is adopted in the application:

a particulate matter for a thermal barrier coating comprising a shell and an inner core;

the porosity of the surface of the shell is less than or equal to 5%; the inner core is provided with first closed pores with the pore diameter of 1-5 mu m, first skeleton microparticles are arranged among the first closed pores, and the particle size of the first skeleton microparticles is 0.1-2 mu m;

the raw materials of the particles comprise one or more of yttria-stabilized zirconia, rare earth oxide-stabilized zirconia, gadolinium zirconate, rare earth oxide-doped modified gadolinium zirconate, cerium zirconate, rare earth oxide-doped modified cerium zirconate and rare earth tantalate.

Preferably, the particle size of the particulate matter is 10-100 μm;

preferably, the thermal conductivity of the raw material is 3W/(m.k) or less;

preferably, the thickness of the shell is 0.1-5 μm.

The application provides a preparation method of the particulate matter for the thermal barrier coating, which comprises the following steps:

and (3) carrying out agglomeration granulation and induction plasma spheroidization on the raw materials to obtain the particles for the thermal barrier coating.

Preferably, the agglomeration granulation comprises:

mixing the powder of the raw material with submicron scale with organic glue, and then obtaining agglomerated powder in a spray drying mode;

preferably, the induction plasma sphering comprises: and (3) feeding the agglomerated powder into high-enthalpy induction plasma formed in a radio frequency induction mode, and heating and cooling to obtain the particles for the thermal barrier coating.

Preferably, the plasma power of the induction plasma spheroidization is 60-80kw, and the powder feeding rate is 30-80 g/min.

The application provides a thermal barrier coating, which is obtained by using the particles for the thermal barrier coating through plasma flame flow jet deposition;

the particulate matter for the thermal barrier coating comprises fine particles with the particle size of 10-25 mu m and coarse particles with the particle size of 50-100 mu m;

the thermal barrier coating has second closed cells with a pore size of 1-5 μm.

Preferably, the thermal barrier coating has a porosity of 30% to 70%;

preferably, the mass ratio of the fine particles to the coarse particles is 1: (2-10).

Preferably, second framework microparticles are arranged between the second closed pores;

preferably, the second backbone microparticle has a particle size of 1 to 5 μm.

Preferably, the power of the plasma flame flow jet is 25-45kw, the powder feeding rate is 25-90g/min, the carrier gas flow is 2.5-9L/min, and the relative moving speed of the jet end and the base material is less than or equal to 0.1 m/s.

The application also provides an engine comprising the thermal barrier coating.

Compared with the prior art, the beneficial effect of this application includes:

the application provides a particulate matter for thermal barrier coating, through adopting "the porosity less than or equal to 5% of the surface that has kernel and casing, the kernel has the first obturator that the aperture is 1-5 mu m, be first skeleton microparticle between the first obturator, the particle diameter of first skeleton microparticle is the structure of the specific size of 0.1-2 mu m" and selects suitable material, good stress buffering effect has been ensured promptly, tiny pore high temperature sintering closed phenomenon has been avoided again, consequently, the high temperature resistance thermal cycle performance of insulating layer can be promoted by a wide margin.

The preparation method of the particulate matter for the thermal barrier coating can stably obtain the particulate matter with the special structure.

The thermal barrier coating provided by the application is obtained by using the particulate matters for the thermal barrier coating through plasma flame flow jet deposition; the coating has a self-closed microporous structure, can effectively prevent external gas from directly diffusing and permeating, and can form separation to heat radiation through the inner surfaces of a large number of pores, thereby exerting excellent heat-insulating property. The microporous structure has the characteristic of regional dispersion distribution, can effectively reduce stress concentration in the coating, and has the effects of delaying crack growth and prolonging the thermal cycle life.

The application provides an engine, high temperature thermal cycle performance is good, long service life.

Drawings

To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments are briefly described below, and it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope of the present application.

FIG. 1 is a schematic structural diagram of a thermal barrier coating provided by an embodiment;

FIG. 2 is an SEM photograph of the particulate material prepared in example 2;

FIG. 3 is an SEM photograph of the thermal barrier coating prepared in example 2;

FIG. 4 is an SEM photograph of the thermal barrier coating prepared in example 2 before and after 1500 ℃ sintering;

FIG. 5 is an SEM photograph of the coating prepared in comparative example 1 before and after sintering at 1500 ℃;

FIG. 6 is a graph of a simulation of the relationship between microvias and coating stress.

Detailed Description

The terms as used herein:

"prepared from … …" is synonymous with "comprising". The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

The conjunction "consisting of … …" excludes any unspecified elements, steps or components. If used in a claim, the phrase is intended to claim as closed, meaning that it does not contain materials other than those described, except for the conventional impurities associated therewith. When the phrase "consisting of … …" appears in a clause of the subject matter of the claims rather than immediately after the subject matter, it defines only the elements described in the clause; other elements are not excluded from the claims as a whole.

When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as a range of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when the range "1 ~ 5" is disclosed, the ranges described should be construed to include the ranges "1 ~ 4", "1 ~ 3", "1 ~2 and 4 ~ 5", "1 ~ 3 and 5", and the like. When a range of values is described herein, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range.

In these examples, the parts and percentages are by mass unless otherwise indicated.

"part by mass" means a basic unit of measure indicating a mass ratio of a plurality of components, and 1 part may represent any unit mass, for example, 1g or 2.689 g. If we say that the part by mass of the component A is a part by mass and the part by mass of the component B is B part by mass, the ratio of the part by mass of the component A to the part by mass of the component B is a: b. alternatively, the mass of the A component is aK and the mass of the B component is bK (K is an arbitrary number, and represents a multiple factor). It is unmistakable that, unlike the parts by mass, the sum of the parts by mass of all the components is not limited to 100 parts.

"and/or" is used to indicate that one or both of the illustrated conditions may occur, e.g., a and/or B includes (a and B) and (a or B).

The compact shell plays a role in structural support and isolation; the structure supporting function is that the compact shell has certain structural strength, so that the powder can be prevented from being dispersed in the powder feeding process; the isolation function is that when the shell of the powder is melted and deposited on the surface of the matrix and the growing coating in the plasma spraying process, the compact shell isolates the internal structure of the powder from the outside, thereby ensuring that the coating obtains better heat insulation performance.

The shell material and the skeleton microparticles in the inner core are partially melted and cooled to form the skeleton and the surface layer of the coating in the coating preparation process, and the closed pores in the inner core provide a source for the closed pores formed in the coating preparation process.

Only if the particles as raw materials have special surface porosity, closed pore diameter, skeleton microparticle particle size and materials of the shell, the prepared coating has a special structure, so that excellent high-temperature thermal cycle performance is obtained.

The material has low thermal conductivity and simultaneously has excellent thermal cycle resistance.

Optionally, the porosity of the surface of the shell may be 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, or any value between 5% or less; the first closed cells may have a pore size of 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or any value between 1 and 5 μm, and the first skeletal microparticles may have a particle size of 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, or any value between 0.1 and 2 μm.

In an alternative embodiment, the particles have a particle size of 10 to 100 μm;

the particles with the particle size range provide guarantee for preparing the thermal barrier coating with excellent performance.

Alternatively, the particle size of the particulate material may be any value between 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 10-100 μm.

In an alternative embodiment, the thermal conductivity of the feedstock is less than or equal to 3W/(m.k);

because the material of the particle raw material is a low-thermal conductivity material, the heat of the powder can not completely penetrate through the powder when the powder passes through the plasma, and therefore the loose porous form of the agglomerated and granulated powder is still reserved inside the particle.

In an alternative embodiment, the thickness of the shell is 0.1-5 μm.

Alternatively, the thickness of the shell may be 0.1 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm or any value between 0.1 and 5 μm.

The particles with the core-shell structure with the compact inner loose shell are obtained through agglomeration granulation and induction plasma spheroidization, wherein the inner pores are randomly distributed and have no specific orientation, so that the pore structure in the subsequently prepared coating also has the characteristics of random distribution and no specific orientation, the coating structure has isotropy, the property is more uniform, and the cracking of the coating caused by stress concentration is reduced.

In an alternative embodiment, the agglomeration granulation comprises:

in an alternative embodiment, the induction plasma sphering comprises: and (3) feeding the agglomerated powder into high-enthalpy induction plasma formed in a radio frequency induction mode, and heating and cooling to obtain the particles for the thermal barrier coating.

In an optional embodiment, the plasma power of the induction plasma spheroidization is 60-80kw, and the powder feeding rate is 30-80 g/min.

The absolute value of the powder feeding rate is 0.5-1 times of the plasma power. The reason for limiting the range is that if the powder feeding rate is too low, the particles are easy to be fully melted, so that the internal microporous structure of the particles disappears; if send whitewashed speed too high, the unable compact shell that forms on particulate matter top layer causes too much through-hole during later stage spraying coating, and heat-proof quality performance descends.

Alternatively, the plasma power may be any value between 60kw, 65kw, 70kw, 75kw, 80kw or 60-80kw, and the powder feeding rate may be any value between 30g/min, 40g/min, 50g/min, 60g/min, 70g/min, 80g/min or 30-80 g/min.

the particulate matter for thermal barrier coating comprises fine particles having a particle size of 10-25 μm and particles having a particle size of 50-100 μm;

The design of a pore structure is mainly considered in the structure of the heat-insulating layer with high temperature resistance, particularly high temperature heat cycle resistance, and the pores in the heat-insulating layer are very important. On the one hand, the thermal radiation can be reflected, the thermal conductivity of the thermal insulation layer is reduced, the better thermal insulation performance is achieved, on the other hand, the thermal stress can be released, and the service life of the coating is prolonged. In an ultrahigh-temperature environment, fine pores and microcracks in a conventional thermal insulation coating are easy to close quickly at ultrahigh temperature; the pore closure not only causes the thermal insulation performance of the coating to be reduced, but also causes the thermal cycle resistance of the coating to be rapidly reduced, so that the coating is prematurely peeled off and the thermal insulation effect is completely lost. Therefore, the pore structure is not preferably too small. And the overlarge pores can cause the severe concentration of the stress at the edges of the pores, trigger the initiation and the propagation of cracks and cause the failure of the coating. In addition, the open pores (pores communicating with the outside) are not reasonable in design, because the open pores are easy for external gas to directly enter the coating and become a high-temperature permeable medium. Reasonable pore size and distribution design is therefore critical. This application not only adopts the closed pore design, moreover through studying the influence of pore size and distribution to thermal stress distribution, has supported the performance advantage of the self-sealing micropore (obturator) insulating layer that this application provided to experimental verification has been carried out.

The closed pores can not be closed in a 1500 ℃ ultrahigh temperature environment, and have excellent high temperature sintering resistance; the direct diffusion and permeation of external gas can be effectively prevented, and the barrier to heat radiation is formed by the inner surfaces of a large number of pores, so that excellent heat-insulating property is exerted; the closed pores have the characteristic of regional dispersion distribution, can effectively reduce stress concentration in the coating, and has the effects of delaying crack growth and prolonging the thermal cycle life.

Alternatively, the fine particles may have a particle size of any value between 10 μm, 15 μm, 20 μm, 25 μm, or 10-25 μm, and the coarse particles may have a particle size of any value between 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or 50-100 μm.

In an alternative embodiment, the thermal barrier coating has a porosity of 30% to 70%;

the porosity of the conventional coating is generally less than 20%, and the closed cell structure under the condition of high porosity can effectively improve the heat insulation performance of the coating.

Optionally, the porosity of the thermal barrier coating pores may be any value between 30%, 40%, 50%, 60%, 70%, or 30% -70%.

In an alternative embodiment, the mass ratio of the fine particles to the coarse particles is 1: (2-10).

Reasonable grading can optimize the performance of the coating. Specifically, the fine particles are more easily melted during the spraying process, and can better bind the coarse particles to form a skeleton structure in the coating, while the coarse particles are only slightly melted by the shell, so that the micropore structure in the particles is more completely transferred to the coating.

Optionally, the mass ratio of the fine particles to the coarse particles may be 1: 2. 1: 3. 1: 4. 1: 5. 1: 6. 1: 7. 1: 8. 1: 9. 1: 10 or 1: (2-10).

In an alternative embodiment, between the second closed cells are second skeletal microparticles;

in an alternative embodiment, the second scaffold microparticle has a particle size of 1 to 5 μm.

Alternatively, the second backbone microparticle may have a particle size of any one of 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or 1 to 5 μm.

In an optional embodiment, the power of the plasma flame flow jet is 25-45kw, the powder feeding rate is 25-90g/min, the carrier gas flow is 2.5-9L/min, and the relative moving speed of the jet end and the substrate is less than or equal to 0.1 m/s.

The absolute value of the powder feeding speed is 1-2 times of the power, and the absolute value of the carrier gas flow is 0.1-0.2 times of the power, so that the powder can be ensured to be more fully conveyed into the plasma flame flow center. The relative movement speed of the spraying end and the base material is controlled, so that large-particle powder can be fully deposited on the base material. The microstructure in the particulate matter can be maximally imparted to the coating by specific power, powder feed rate and carrier gas flow rate.

Optionally, the power of the plasma flame stream jet can be any value between 25kw, 30kw, 35kw, 40kw, 45kw or 25-45kw, the powder feeding rate can be any value between 25g/min, 30g/min, 35g/min, 40g/min, 45g/min, 50g/min, 55g/min, 60g/min, 65g/min, 70g/min, 75g/min, 80g/min, 85g/min, 90g/min or 25-90g/min, the carrier gas flow can be any value between 2.5L/min, 3L/min, 3.5L/min, 4L/min, 4.5L/min, 5L/min, 5.5L/min, 6L/min, 6.5L/min, 7L/min, 7.5L/min, 8L/min, 8.5L/min, 9L/min or any value between 2.5 and 9L/min.

The application also provides an engine comprising the thermal barrier coating.

Embodiments of the present application will be described in detail below with reference to specific examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present application and should not be construed as limiting the scope of the present application. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Example 1

The embodiment provides a particulate matter for a thermal barrier coating, which is prepared by the following specific method:

the particle is prepared by taking gadolinium zirconate as a raw material through two steps of agglomeration granulation and induction plasma spheroidization.

Wherein, the agglomeration granulation is to mix fine powder with submicron scale with organic glue (PVA, the mass is 10 percent of the mass of the powder) and obtain agglomerated powder in a spray drying mode, and the agglomerated powder has a loose and porous internal structure. The average size of microparticles in the agglomerated powder is 0.1 mu m, the average size of micropores is 5 mu m, and the particle size range of the powder is 10-100 mu m. The induction plasma spheroidization is to send the agglomerated powder into high-enthalpy induction plasma formed in a radio frequency induction mode, and the agglomerated powder is heated by the high-temperature plasma, then the surface of the agglomerated powder is melted and cooled to form a compact shell; sensing plasma process parameters includes: the power is 60kW, and the powder feeding speed is 60 g/min. Finally, through the powder preparation process, the particles with the core-shell structure and the loose and compact inner shell are obtained. The average porosity of the outer shell of the particulate material was 5%, the average thickness of the outer shell was 1 μm, the average size of the inner microparticles was 0.1 μm, and the average size of the micropores was 5 μm.

As shown in fig. 1, this embodiment further provides a thermal barrier coating, and the preparation method thereof is as follows:

according to the mass ratio of 10-25 mu m fine particles to 50-100 mu m coarse particles of 1: 2 mixing to obtain powder, and then preparing the heat-insulating coating by adopting a plasma spraying process.

The plasma spraying power is 25kW, the powder feeding rate is 50g/min, the carrier gas flow is 2.5L/min, and the moving speed of the spray gun relative to the base material is 0.1 m/s. The porosity of the prepared heat-insulating coating is 50%, the average size of micropores is 5 microns, and the average size of a framework is 0.5 microns; the periphery of the micropore has no penetrating crack, so the micropore is not communicated with the outside.

After high-temperature heat treatment at 1500 ℃, the coating still keeps a microporous structure. Through thermal cycle examination (thermal cycle test is carried out by adopting a high-temperature gas flame thermal shock mode), the coating of the microporous coating does not lose efficacy after 100 hours of cumulative cycle, and the microporous coating shows excellent high-temperature resistance thermal cycle performance.

Example 2

the particles are prepared by using yttria-stabilized zirconia as a raw material through two steps of agglomeration granulation and induction plasma spheroidization.

Wherein, the agglomeration granulation is to mix fine powder with submicron scale with organic glue and then obtain agglomerated powder in a spray drying mode, and the agglomerated powder has a loose and porous internal structure. The average size of microparticles in the agglomerated powder is 1 mu m, the average size of micropores is 3 mu m, and the particle size range of the powder is 10-100 mu m. The induction plasma spheroidization is to send the agglomerated powder into high-enthalpy induction plasma formed in a radio frequency induction mode, and the agglomerated powder is heated by the high-temperature plasma, then the surface of the agglomerated powder is melted and cooled to form a compact shell; sensing plasma process parameters includes: the power is 80kW, and the powder feeding speed is 40 g/min. Finally, through the powder preparation process, the particles with the core-shell structure and the loose and compact inner shell are obtained. The average porosity of the outer shell of the particulate matter was 2%, the average thickness of the outer shell was 5 μm, the average size of the inner fine particles was 0.5 μm, and the average size of the micropores was 1 μm.

Fig. 2 is an SEM photograph of the above-mentioned particulate matter.

The embodiment also provides a thermal barrier coating, and the preparation method comprises the following steps:

according to the mass ratio of 10-25 mu m fine particles to 50-100 mu m coarse particles of 1: 5 mixing to obtain powder, and then preparing the heat-insulating coating by adopting a plasma spraying process.

The plasma spraying power was 45kW, the powder feeding rate was 45g/min, the carrier gas flow rate was 4.5L/min, and the moving speed of the spray gun relative to the base material was 0.05 m/s. The porosity of the prepared heat insulation coating is 30%, the average size of micropores is 1 mu m, and the average size of a framework is 1 mu m; the periphery of the micropore has no penetrating crack, so the micropore is not communicated with the outside.

Fig. 3 is an SEM photograph of the above thermal barrier coating.

After high-temperature heat treatment at 1500 ℃, the coating still keeps a microporous structure. Through thermal cycle examination, the microporous coating does not lose efficacy after cumulative cycle for 100 hours, and shows excellent high-temperature thermal cycle resistance.

FIG. 4 is SEM pictures of the coating before (left) and after (right) sintering at 1500 ℃.

Example 3

Wherein, the agglomeration granulation is to mix fine powder with submicron scale with organic glue and then obtain agglomerated powder in a spray drying mode, and the agglomerated powder has a loose and porous internal structure. The average size of microparticles in the agglomerated powder is 0.1 mu m, the average size of micropores is 5 mu m, and the particle size range of the powder is 10-100 mu m. The induction plasma spheroidization is to send the agglomerated powder into high-enthalpy induction plasma formed in a radio frequency induction mode, and the agglomerated powder is heated by the high-temperature plasma, then the surface of the agglomerated powder is melted and cooled to form a compact shell; sensing plasma process parameters includes: the power is 60kW, and the powder feeding speed is 30 g/min. Finally, through the powder preparation process, the particles with the core-shell structure and the loose and compact inner shell are obtained. The average porosity of the outer shell of the particulate material was 3%, the average thickness of the outer shell was 3 μm, the average size of the inner microparticles was 0.5 μm, and the average size of the micropores was 2 μm.

according to the mass ratio of 10-25 mu m fine particles to 50-100 mu m coarse particles of 1: 10 to obtain powder, and then preparing the heat-insulating coating by adopting a plasma spraying process.

The plasma spraying power is 25kW, the powder feeding rate is 50g/min, the carrier gas flow is 2.5L/min, and the moving speed of the spray gun relative to the base material is 0.1 m/s. The porosity of the prepared heat-insulating coating is 42%, the average size of micropores is 4 microns, and the average size of a framework is 0.8 micron; the periphery of the micropore has no penetrating crack, so the micropore is not communicated with the outside.

Example 4

Wherein, the agglomeration granulation is to mix fine powder with submicron scale with organic glue and then obtain agglomerated powder in a spray drying mode, and the agglomerated powder has a loose and porous internal structure. The average size of microparticles in the agglomerated powder is 0.1 mu m, the average size of micropores is 5 mu m, and the particle size range of the powder is 10-100 mu m. The induction plasma spheroidization is to send the agglomerated powder into high-enthalpy induction plasma formed in a radio frequency induction mode, and the agglomerated powder is heated by the high-temperature plasma, then the surface of the agglomerated powder is melted and cooled to form a compact shell; sensing plasma process parameters includes: the power is 80kW, and the powder feeding speed is 40 g/min. Finally, through the powder preparation process, the particles with the core-shell structure and the loose and compact inner shell are obtained. The average porosity of the outer shell of the particulate matter was 2%, the average thickness of the outer shell was 5 μm, the average size of the inner fine particles was 0.5 μm, and the average size of the micropores was 1 μm.

according to the mass ratio of 10-25 mu m fine particles to 50-100 mu m coarse particles of 1: 8, mixing to obtain powder, and then preparing the heat-insulating coating by adopting a plasma spraying process.

The plasma spraying power was 45kW, the powder feeding rate was 45g/min, the carrier gas flow rate was 4.5L/min, and the moving speed of the spray gun relative to the base material was 0.05 m/s. The porosity of the prepared heat insulation coating is 45%, the average size of micropores is 1 mu m, and the average size of a framework is 1 mu m; the periphery of the micropore has no penetrating crack, so the micropore is not communicated with the outside.

Example 5

Wherein, the agglomeration granulation is to mix fine powder with submicron scale with organic glue and then obtain agglomerated powder in a spray drying mode, and the agglomerated powder has a loose and porous internal structure. The average size of microparticles in the agglomerated powder is 0.1 mu m, the average size of micropores is 5 mu m, and the particle size range of the powder is 10-100 mu m. The induction plasma spheroidization is to send the agglomerated powder into high-enthalpy induction plasma formed in a radio frequency induction mode, and the agglomerated powder is heated by the high-temperature plasma, then the surface of the agglomerated powder is melted and cooled to form a compact shell; sensing plasma process parameters includes: the power is 60kW, and the powder feeding speed is 60 g/min. Finally, through the powder preparation process, the particles with the core-shell structure and the loose and compact inner shell are obtained. The average porosity of the outer shell of the particulate material was 5%, the average thickness of the outer shell was 1 μm, the average size of the inner microparticles was 0.1 μm, and the average size of the micropores was 5 μm.

according to the mass ratio of 10-25 mu m fine particles to 50-100 mu m coarse particles of 1: 6 mixing to obtain powder, and then preparing the heat-insulating coating by adopting a plasma spraying process.

The plasma spraying power is 25kW, the powder feeding rate is 25g/min, the carrier gas flow is 2.5L/min, and the moving speed of the spray gun relative to the base material is 0.1 m/s. The porosity of the prepared heat-insulating coating is 37 percent, the average size of micropores is 3 mu m, and the average size of a framework is 0.8 mu m; the periphery of the micropore has no penetrating crack, so the micropore is not communicated with the outside.

Comparative example 1

The coating was prepared by plasma spraying using a powder having nano-pores (average size of micro-particles 0.05 μm, average size of micro-pores 0.05 μm). The parameters of the induction plasma process and the plasma spray process were the same as in example 1. The prepared thermal insulation coating has low porosity (12%), and has a structure of nano-pores and nano-particles in the interior, wherein the average size of the nano-pores is about 0.05 μm, and the average size of the skeleton is 0.05 μm. The nano-pores in the coating completely disappear after the high-temperature heat treatment at 1500 ℃, and a compact coating is formed. The nano-pore coating fails after 10 hours of cumulative cycle through thermal cycle examination, and the thermal cycle life is obviously shorter than that of the coating in example 1.

The nanometer particle powder is easy to cause low porosity of the coating, and sintering phenomenon at high temperature leads to reduced stress tolerance of the coating and short service life.

FIG. 5 is SEM photographs of the coating before (left) and after (right) 1500 deg.C high temperature heat treatment.

Comparative example 2

In contrast to example 1, the induction plasma milling was carried out using a high powder feed rate (70 g/min), and the obtained core-shell particles were not shaped, with the average porosity of the shell of the partially shaped particles being > 30% and the average thickness of the shell being < 1 μm.

When the powder is prepared, the powder feeding speed is too high, the induction plasma flame flow is discontinuous, so that the powder cannot normally form a compact shell, and the spraying effect and the coating forming are seriously influenced.

When the same plasma spraying process parameters are adopted, the coating cannot be normally formed due to poor powder fluidity and discontinuous spraying flame, so that the high-temperature thermal cycle life of the coating cannot be obtained.

Comparative example 3

In contrast to example 2, a low powder feed rate (20 g/min) was used in the induction plasma milling, resulting in a particle shell with an average porosity of 2%, an average shell thickness of 7 μm, an average inner particle size of 0.8 μm and an average pore size of 0.5. mu.m.

Using the same coating preparation process as in example 2, the resulting coating had a porosity of 23%, a mean pore size of 0.5 μm, and a mean skeleton size of 3 μm; through thermal cycle examination, the coating of the nano-pore coating fails when the cumulative cycle is 35 hours, and the thermal cycle life is obviously shorter than that of the coating of the example 2.

When the powder is prepared, the powder feeding rate is too low, the powder is excessively melted, the shell is too thick, finer sub-micropores are formed instead of micropores, and the sub-micropores are easy to sinter and disappear in the ultrahigh temperature thermal cycle process, so that the thermal cycle stress of the coating is increased, and the service life is lower.

Comparative example 4

In contrast to example 1, the coating of the granulate was produced without fine and coarse grading.

The porosity of the obtained coating is 18%, the average size of micropores is 0.3 mu m, and the average size of a framework is 8 mu m; the nanoporous coatings were found to fail at 22 hours of cumulative cycling through thermal cycling examination, with significantly lower thermal cycling life than the example 1 coatings.

When the graded-free powder is used, the fine powder absorbs heat to deposit into a coating during spraying, the proportion of large-particle powder deposited into the coating is obviously reduced, so that the microporous structure cannot be well inherited into the coating, the porosity and the pore size are obviously reduced, and the service life of the coating is shortened.

Comparative example 5

Unlike example 1, when the coating was prepared from the granules, the mass ratio of the fine particles to the coarse particles was 0.05: 1.

no shaped coating can be obtained.

The powder proportion of the fine-grained section is too small, and the bonding effect on the coarse-grained powder cannot be formed when the coating is sprayed, so that the powder cannot be effectively deposited on the base material, and the coating cannot be formed.

Comparative example 6

Unlike example 2, when the coating was prepared from the granules, the mass ratio of the fine particles to the coarse particles was 0.3: 1.

the porosity of the obtained coating is 24%, the average size of micropores is 1 mu m, and the average size of a framework is 3 mu m; the nanoporous coatings were found to fail at 58 hours of cumulative cycling through thermal cycling examination, with significantly lower thermal cycling life than the example 2 coatings.

The powder proportion of the fine-grained section is too high, the porosity of the sprayed coating is low, the thermal stress release capacity of the coating is reduced, and the thermal cycle life of the coating is shortened.

Comparative example 7

In contrast to example 1, the coating was produced at a speed of 0.2m/s of movement of the spray gun relative to the substrate.

No shaped coating can be obtained.

When the gun is moved too fast, the powder cannot be effectively deposited onto the substrate surface and the coating is not formed.

Comparative example 8

In contrast to example 2, the powder feed rate was 20g/min when the coating was prepared.

The porosity of the obtained coating is 21%, the average size of micropores is 0.6 mu m, and the average size of a framework is 5 mu m; the nanoporous coating was found to fail at 48 hours of cumulative cycling through thermal cycling examination, with a significantly lower thermal cycling life than the coating of example 2.

When the powder feeding rate of spraying is too low, the powder is over-melted, the size of a microporous structure is reduced, the porosity of a coating is reduced, the stress tolerance is reduced, and the service life is shortened.

The thermal barrier coating prepared by the method has the ultra-high temperature thermal cycle life of more than 100 hours, while the conventional nano coating is generally about 10 hours and the conventional coating is about 35 hours.

To further illustrate the relationship between pore size of the micropores and coating stress, simulations were performed on pore size and stress distribution, and the results are shown in fig. 6.

Wherein the aperture of a is 10.9 μm, the aperture of b is 6.3 μm, and the aperture of c is 2.7 μm; as can be seen from FIG. 6, with the reduction of the pore size, the stress peak value is significantly reduced, the distribution is more uniform, the thermal cycle resistance of the coating is favorably improved, and the thermal cycle life of the coating is prolonged.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Moreover, those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the application and form different embodiments. For example, in the claims above, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is only for enhancement of understanding of the general background of the application and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Claims

1. A particulate material for a thermal barrier coating, comprising a shell and an inner core;

2. Particulate matter for use in thermal barrier coatings according to claim 1, characterised in that the particle size of the particulate matter is 10-100 μ ι η;

the thermal conductivity of the raw material is less than or equal to 3W/(m.K);

the thickness of the shell is 0.1-5 μm.

3. A method of preparing particulate matter for use in thermal barrier coatings according to claim 1 or 2, comprising:

4. A method of manufacturing as claimed in claim 3, wherein said agglomerating granulation comprises:

the induction plasma sphering includes: and (3) feeding the agglomerated powder into high-enthalpy induction plasma formed in a radio frequency induction mode, and heating and cooling to obtain the particles for the thermal barrier coating.

5. The method according to claim 3 or 4, wherein the plasma power of the induction plasma spheroidization is 60-80kw, and the powder feeding rate is 30-80 g/min.

6. A thermal barrier coating, characterized in that particulate matter for use in a thermal barrier coating as claimed in claim 1 or 2 is deposited by plasma flame stream injection;

7. The thermal barrier coating of claim 6, wherein the thermal barrier coating has a porosity of 30-70%;

the mass ratio of the fine particles to the coarse particles is 1: (2-10).

8. The thermal barrier coating of claim 6, wherein between the second closed cells are second skeletal microparticles;

the particle size of the second skeleton microparticle is 1-5 μm.

9. The thermal barrier coating of any of claims 6 to 8, wherein the plasma plume ejection power is in the range of 25kw to 45kw, the powder feed rate is in the range of 25g/min to 90g/min, the carrier gas flow rate is in the range of 2.5L/min to 9L/min, and the relative movement speed of the ejection tip and the substrate is 0.1m/s or less.

10. An engine, characterized by comprising a thermal barrier coating according to any of claims 6 to 9.