CN111304576B

CN111304576B - Metal/polyphenyl ester heterogeneous particle mechanical agglomeration coating powder and preparation method thereof

Info

Publication number: CN111304576B
Application number: CN201911240886.6A
Authority: CN
Inventors: 于月光; 刘建明; 沈婕; 章德铭; 卢晓亮; 刘通; 郭丹; 黄凌峰; 候伟骜; 石长江; 原慷
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: 2019-12-06
Filing date: 2019-12-06
Publication date: 2022-02-01
Anticipated expiration: 2039-12-06
Also published as: CN111304576A

Abstract

The invention relates to a metal/polyphenyl ester heterogeneous particle mechanical agglomeration coating powder and a preparation method thereof. Specifically, the invention provides a powder composition, which comprises metal powder and plastic powder; wherein the metal powder contains spheroidal main particles, and one or more of the main particles are attached with spheroidal satellite spheres on the surface; wherein the bulk density B, the true density rho and the particle diameters D10, D50 and D90 of the metal powder satisfy the following relational expression (D90-D10)/(D50-D10) (B/rho) ═ 1.0-1.1; wherein the particle size parameters D10, D50 and D90 of the plastic powder satisfy the following relational expression (D90-D10)/(D50-D10) of 2.0-2.5; wherein the mass ratio of the plastic powder to the metal powder is 0.1-100: 0.1-100. The powder composition can be used for preparing plasma spray coatings.

Description

Metal/polyphenyl ester heterogeneous particle mechanical agglomeration coating powder and preparation method thereof

Technical Field

The invention relates to the field of materials, in particular to metal/polyphenyl ester heterogeneous particle mechanical agglomeration coating powder and a preparation method thereof.

Background

Abradable/wear-resistant antifriction coatings find wide use in the manufacture and maintenance of mechanical equipment, such coatings typically comprising a metal skeleton component to support their strength and a plastic component to improve their tribological properties.

The related art uses a thermal spraying method to spray a powder composition containing metal powder and plastic powder on the surface of a substrate to form an abradable/wear-resistant antifriction coating.

The polyphenyl ester powder has the advantages of good thermal stability, high compressive strength, small friction coefficient, stable chemical property and the like. It can be used for preparing abradable coating/wear-resistant antifriction coating.

Disclosure of Invention

The starting powders used to produce the abradable coating typically contain metal powders and plastic powders. The related art has considered that plastic powder having a wide particle size distribution as a raw material is not favorable for forming an abradable coating having good quality. However, the inventors have surprisingly found that the use of a metal powder having a specific particle size characteristic in combination with a plastic powder having a broad particle size distribution as a thermal spray raw material enables to obtain a coating of good quality.

In some aspects, a powder composition is provided, comprising a metal powder and a plastic powder;

wherein the metal powder contains spheroidal main particles, and one or more of the main particles are attached with spheroidal satellite spheres;

wherein the bulk density B, true density ρ and particle diameters D10, D50, and D90 of the metal powder satisfy the following relational expression (D90-D10)/(D50-D10) × (B/ρ) ═ 1.0 to 1.1 (e.g., 1.01 to 1.05, e.g., 1.01 to 1.03);

wherein the particle size parameters D10, D50 and D90 of the plastic powder satisfy the following relations (D90-D10)/(D50-D10) ═ 2.0-2.5, for example 2.2-2.3;

wherein the mass ratio of the plastic powder to the metal powder is 0.1-100: 0.1-100. For example, 1 to 100: 1 to 100, for example 1 to 10:1 to 10, for example 0.1 to 10:1, for example 0.6 to 9:1, for example, 0.6 to 0.7: 1, for example 8 to 10: 1.

in some embodiments, one or more satellite spheres are attached to the surface of one or more metal powder particles in the powder composition.

In some embodiments, the primary particle has a particle size that is more than 2 times, e.g., more than 5 times, the particle size of the satellite spheres.

In some embodiments, the primary particles have a particle size distribution substantially ranging from 5 to 25 μm, and the satellite spheres have a particle size distribution substantially ranging from 0.5 to 3 μm.

In some embodiments, the ratio B rho of the bulk density B to the true density rho of the metal powder is from 0.35 to 0.5, such as from 0.40 to 0.43.

In some embodiments, the metal powder has a D10 of 5 to 40 μm, such as 5 to 10 μm, such as 10 to 15 μm, such as 15 to 20 μm, such as 20 to 25 μm, such as 25 to 30 μm, such as 30 to 35 μm, such as 35 to 40 μm; d50 is 20-50 μm, for example 20-30 μm, for example 30-40 μm, for example 40-50 μm; d90 is 40-70 μm, for example 40-50 μm, for example 50-60 μm, for example 60-70 μm.

In some embodiments, D10 < D50 < D90.

In some embodiments, the metal powder has a (D90-D10)/(D50-D10) of 2.0 to 2.6, such as 2.1 to 2.2, such as 2.3 to 2.4, such as 2.5 to 2.6, such as 2.3 to 2.6.

In some embodiments, the metal powder has a bulk density B of 1 to 4g/cm³For example, 1 to 2g/cm³For example, 2 to 3g/cm³For example, 3 to 4g/cm³。

In some embodiments, the metal powder has a true density ρ of 2 to 10g/cm³For example, 2 to 4g/cm³E.g. 7 to 9g/cm³。

In some embodiments, the metal powder has a ratio of bulk density to true density (B/ρ) of 0.3 to 0.5.

In some embodiments, the plastic powder is prepared using a size reduction method.

In some embodiments, the plastic powder has a D10 of 8-20 μm, a D50 of 55-80 μm, a D90 of 110-150 μm, and a D10 < D50 < D90.

In some embodiments, the plastic powder has a D10 of 10-20 μm, a D50 of 63-73 μm, a D90 of 130-140 μm, and a D10 < D50 < D90.

In some embodiments, the plastic powder has a D10 of 10-25 μm, a D50 of 65-70 μm, a D90 of 133-137 μm, and a D10 < D50 < D90.

In some embodiments, the plastic powder has a (D90-D10)/(D50-D10) of 2 to 2.5, such as 2.1 to 2.3.

In some embodiments, the bulk density B of the plastic powder is from 0.3 to 0.8g/cm³For example, 0.4 to 0.6g/cm³。

In some embodiments, the plastic powder has a true density ρ of 1 to 2g/cm³For example, 1.4 to 1.5g/cm³。

In some embodiments, the ratio of bulk density to true density (B/ρ) of the plastic powder is from 0.3 to 0.5, such as from 0.3 to 0.4.

In some embodiments, the metal powder is an aluminum alloy powder, such as an AlSi alloy powder. Optionally, in the AlSi alloy, the weight ratio of the Al element to the Si element is 1: 20 to 25.

In some embodiments, the metal powder is a superalloy powder, such as a NiCrAlY alloy powder. Optionally, in the NiCrAlY alloy, the weight ratio of the Ni element, the Cr element, the Al element, and the Y element is 1: 25-30: 5-10: 0.3 to 0.8.

In some embodiments, the plastic powder is a polyester powder, such as a polyphenyl ester powder, a polyurethane powder, or the like.

In some embodiments, the plastic powder is a polyphenyl ester powder, the number average molecular weight of the polyphenyl ester is 5000-10000, such as 6000-7000.

In some embodiments, the powder composition further comprises a binder, optionally the binder is polyvinyl alcohol. Optionally, the content of the binder is 0.1-10 wt%.

In some embodiments, the metal powder is homogeneously mixed with the plastic powder in the powder composition.

In some aspects, there is provided a method of preparing a powder composition comprising the steps of:

providing a metal powder containing spheroidal main particles, wherein one or more surfaces of the main particles are attached with spheroidal satellite spheres, and the apparent density B, the true density rho and the particle diameters D10, D50 and D90 of the metal powder satisfy the following relational expression (D90-D10)/(D50-D10) (B/rho) ═ 1.0-1.1, such as 1.01-1.03;

providing a plastic powder satisfying the following relation (D90-D10)/(D50-D10) of 2.0 to 2.5, for example 2.2 to 2.3;

mixing a metal powder and a plastic powder;

wherein the mass ratio of the plastic powder to the metal powder is 0.1-100: 0.1 to 100. For example, 1 to 100: 1 to 100, for example 1 to 10:1 to 10, for example 0.1 to 10:1, for example 0.6 to 9:1, for example, 0.5 to 1: 1, for example 8 to 10: 1.

in some embodiments, the metal powder is provided at a temperature of-30 ℃ to 30 ℃.

In some embodiments, the plastic powder is provided at a temperature of-30 ℃ to 0 ℃, e.g., -30 ℃ to-20 ℃.

In some embodiments, the metal powder comprises spheroidal particles with satellite spheres attached to the surface.

In some embodiments, the metal powder comprises spheroidal primary particles, one or more of the primary particles further having spheroidal satellites attached to the surface thereof.

In some embodiments, the metal powder is any one of the metal powders described above.

In some embodiments, the plastic powder is any one of the plastic powders described above.

In some embodiments, the powder composition further comprises a binder, optionally the binder is polyvinyl alcohol.

In some embodiments, the above method further comprises: a binder is added to the combination of metal powder and plastic powder before or during stirring.

Preferably, the binder is polyvinyl alcohol.

Preferably, the binder is added in an amount of 0.1 to 10 wt%, for example 0.1 to 1 wt%.

In some embodiments, the metal powder and the plastic powder are mixed under the action of mechanical force (e.g., tumbling, stirring).

In some embodiments, the metal powder and the plastic powder are stirred in a stirring vessel having a stirring paddle at a speed of 10 to 50r/min for a period of 10 to 100 min.

In some embodiments, the AlSi alloy powder is prepared by a high-pressure gas atomization method, a metal raw material is heated to melt and form a melt at 800-900 ℃, and then the melt flows downwards through a discharge nozzle and is atomized under the action of high-pressure gas to form the metal powder, wherein the atomization parameters are as follows: the diameter of the discharge spout is 8-10 mm, the height of the discharge spout is 30-35 mm, the atomizing gas is nitrogen (purity is 99.95%), the pressure of the atomizing gas is 4-5 MPa, a circular seam type nozzle is adopted, and the width of a circular seam is 0.5-0.7 mm. After the atomization is finished, the atomized aluminum-silicon powder is collected after the material is cooled, and the metal powder which meets the particle size distribution is obtained by adopting airflow classification.

In some embodiments, a high pressure gas atomization process is used to produce a NiCrAlY alloy powder. Heating metal raw materials to melt and form a melt of 1500-1600 ℃, then enabling the melt to flow downwards through a discharge spout, and atomizing the melt under the action of high-pressure gas to form metal powder, wherein the atomization parameters are as follows: the diameter of the discharge spout is 8-10 mm, the height of the discharge spout is 38-42 mm, the pressure of atomizing gas is 4-5 MPa, a circular seam type nozzle is adopted, and the width of the circular seam is 0.5-0.7 mm. And after the atomization is finished, collecting atomized NiCrAlY powder after the material is cooled, and obtaining the metal powder according with the particle size distribution by adopting airflow classification.

In some embodiments, the metal powder and the plastic powder are stirred in an electrically conductive stirring vessel, and the electrically conductive stirring vessel is electrically connected to ground. Based on the method, the agglomeration of the plastic powder can be avoided, and the uniformity of powder mixing is improved.

In some aspects, a powder composition is provided, obtained by the above-described method.

In some aspects, a method of forming a thermal spray coating on a surface of a substrate is provided, comprising performing thermal spraying on the surface of the substrate using the above powder composition as a spraying medium.

Preferably, the thermal spraying is plasma spraying.

In some aspects, a thermal spray coating is provided, obtained by the method described above.

Description of terms:

if the following terms are used in the present invention, they may have the following meanings:

"Plastic" refers to a material that is composed of or has resin as a main component. Resins, also known as high molecular weight polymers.

"substantially" in "a distribution of particle sizes substantially in the range of α to β μm" means that at least 90% by number of the particles have a particle size distribution in the above range, or at least 95% by number of the particles have a particle size distribution in the above range, or 100% by number of the particles have a particle size distribution in the above range.

"distributed in the range of α to β μm" means that particles having a particle size as small as α μm are present, and particles having a particle size as large as β μm are also present.

The term "spheroidal" includes ideal spherical shapes and shapes similar thereto. In the present invention, the terms "spheroidal" and "spherical" are used interchangeably.

D10 shows the particle size corresponding to the powder with a cumulative particle size distribution percentage of 10%, D50 shows the particle size corresponding to the powder with a cumulative particle size distribution percentage of 50%, and D90 shows the particle size corresponding to the powder with a cumulative particle size distribution percentage of 90%.

The term "primary particles" is used with respect to satellite spheres, some of which are attached to the surface of the primary particles, the satellite spheres having a smaller particle size than the primary particles.

AlSi-alloy means an alloy of the elements Al and Si, the sum of which is more than 70% by weight, for example more than 90% by weight, in the alloy.

NiCrAlY means an alloy of elements Ni, Cr, Al and Y, the sum of these four elements being greater than 70% by weight, for example greater than 90% by weight, of the alloy.

Polybenzoate, also known as poly-p-hydroxybenzoate or poly-oxybenzoyl, abbreviated PHB, and known by the acronym p-polybenzoic acid polymer.

Advantageous effects

The disclosed methods or products have one or more of the following advantages:

despite the use of plastic powder raw materials with a broad particle size distribution, the mixed powder of the present disclosure produces coatings with a uniform hardness distribution;

despite the use of plastic powder raw materials with a wide particle size distribution, the mixed powder of the present disclosure produces coatings with a uniform network surface morphology with the plastic component uniformly distributed in the network formed by the metal component;

despite the use of plastic powder raw materials with a wide particle size distribution, the mixed powder of the present disclosure produces coatings with lower ablation rates of the plastic components and higher plastic content in the resulting coatings.

Drawings

FIG. 1 is a scanning electron micrograph of an AlSi alloy powder of example 1;

FIG. 2 is a scanning electron micrograph of the polyphenylene ether powder of example 1;

FIG. 3 is a scanning electron micrograph of an AlSi/polyphenylene ether mixed powder of example 1;

FIG. 4 is a scanning electron microscope photograph of the cross-sectional position of the coating of example 1;

FIG. 5 is a scanning electron microscope photograph of the cross-sectional position of the coating of comparative example 1;

FIG. 6 is a scanning electron micrograph of a NiCrAlY powder of example 2 a;

FIG. 7 is a SEM photograph of a NiCrAlY/polybenzoate mixed powder of example 2 a.

FIG. 8 is a scanning electron micrograph of a NiCrAlY powder of comparative example 2;

FIG. 9 is a scanning electron micrograph of a cross-sectional position of the coating of example 2 a;

fig. 10 is a scanning electron microscope photograph of the cross-sectional position of the coating layer of comparative example 2.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. 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 commercially available.

The following examples were used for performance parameter characterization as follows.

1) Apparent density: GBT 1479.1-2011 determination of metal powder apparent density

2) Particle size distribution: GBT 19077-2016 particle size analysis laser diffraction method

3) Coating hardness: HB 5486-1991 thermal spraying coating hardness test method

Example 1

(1) AlSi alloy (Al-12Si, i.e., Al and Si in a weight ratio of 1: 12) powder is provided. Fig. 1 shows a scanning electron micrograph (800 ×) of the AlSi alloy powder. In a visual field, the AlSi alloy powder comprises spherical main particles, wherein spherical satellite spheres are attached to the surfaces of the main particles, the particle size of the main particles is basically distributed within the range of 5-25 mu m, and the particle size of the satellite spheres is basically distributed within the range of 0.5-3 mu m.

The preparation method of the alloy powder comprises the following steps: preparing aluminum-silicon alloy powder by adopting a vacuum atomization system, feeding into a medium-frequency induction furnace according to a mode of firstly feeding silicon and then feeding aluminum, wherein the weight ratio of Si to Al is 3: 22. Melting the burden with a power of 45kW, then heating the melt with a power of 120kW, and starting atomization when the melt temperature reaches 850 ℃, wherein the atomization parameters are as follows: the diameter of the discharge spout is 9mm, the height of the discharge spout is 32mm, the atomizing gas is nitrogen (purity is 99.95%), the pressure of the atomizing gas is 4.5MPa, and the width of the circular seam is 0.6 mm. After the atomization is finished, the atomized aluminum-silicon powder is collected after the material is cooled, and the powder with the particle size distribution according with the table 1.1 is obtained by adopting airflow classification.

(2) The polyphenyl ester powder obtained by the crushing and grading method (manufactured by Zhonghao Chen photochemical research institute, the trademark is GCZ-2) has the number average molecular weight of 6500-7000, and the thermal weight loss is not more than 3% after the heat preservation is carried out for 2h at the temperature of 400 ℃ in the air. Figure 2 shows a scanning electron micrograph of a polyphenylene ether powder, which is irregularly shaped. The polyphenyl ester powder was frozen in a refrigerator at-10 ℃ for 30 minutes.

(3) Mixing the frozen polyphenyl ester powder and the AlSi alloy powder according to the weight ratio of 2:3, and placing the mixture in a stainless steel mixing barrel, wherein the outer side of the stainless steel mixing barrel is connected with the ground through a copper wire with the diameter of 2 mm. A linear stirring paddle with the diameter of 40cm is arranged in the stirring barrel, and the stirring is carried out for 15min at the speed of 30 r/min.

(4) Then adding polyvinyl alcohol binder accounting for 5 percent of the total weight of the powder into a stirring barrel, and stirring for 60min to obtain AlSi/polyphenyl ester mixed powder.

Table 1.1 shows the powder particle size parameters of AlSi alloy powder, polyphenyl ester powder and AlSi/polyphenyl ester mixed powder.

TABLE 1.1

FIG. 3 shows a scanning electron micrograph of AlSi/polyphenyl ester mixed powder, in which a photograph of one polyphenyl ester powder particle encapsulated by a plurality of AlSi alloy powder particles is shown.

Comparative example 1

Comparative example 1 differs from example 1 in the AlSi alloy powder. The grain size characteristics of the AlSi alloy powder of comparative example 1 are shown in table 1.2 below.

The AlSi alloy powder is prepared using the following atomization parameters: preparing aluminum-silicon alloy powder by adopting a vacuum atomization system, feeding into a medium-frequency induction furnace according to a mode of firstly feeding silicon and then feeding aluminum, wherein the weight ratio of Si to Al is 3: 22. Melting the furnace burden with 45kW of power, then heating the melt with 140kW of power, and starting atomization when the temperature of the atomized melt is 850 ℃, wherein the atomization parameters are as follows: the diameter of the discharge spout is 9mm, the height of the discharge spout is 32mm, the atomizing gas is nitrogen (purity is 99.95%), the pressure of the atomizing gas is 2.0MPa, and the width of the circular seam is 0.6 mm. After the atomization is finished, the atomized aluminum-silicon powder is collected after the material is cooled, and the alloy powder with the particle size distribution according with the table 1.2 is obtained by adopting airflow classification.

TABLE 1.2

Due to the different atomization gas pressures of the vacuum atomization of example 1 and comparative example 1, the powder products have different morphology and particle size characteristics.

Analysis and detection 1:

the powders of example 1 and comparative example 1 were sprayed onto TC4 titanium alloy substrates using atmospheric plasma spraying. Spraying equipment: the Metco F4 type spray gun, spray thickness 1.5mm, spray parameters are shown in table 1.3 below.

TABLE 1.3

The properties of the resulting coating are shown in table 1.4 below. Fig. 4 and 5 show cross-sectional scanning electron micrographs of the coatings of example 1 and comparative example 1, respectively.

TABLE 1.4

Serial number	Powder appearance	Uniformity of coating hardness	Burning loss of polyphenyl ester	Morphology of
					Example 1	Color uniformity	50～60HR15Y	4.6％	FIG. 4
Comparative example 1	Color unevenness	60～85HR15Y	12.5％	FIG. 5

The detection method of the coating hardness uniformity comprises the following steps: the method is carried out according to the method of HB 5486-1991, namely 10 points are measured on the coating, the range of the maximum value and the minimum value of the measured data is taken as the hardness uniformity, and the smaller the range, the better the hardness uniformity of the coating is shown.

The burning loss rate of the polyphenyl ester is calculated according to the following formula:

the burning loss rate of the polyphenyl ester is (the content of the polyphenyl ester in the powder-the content of the polyphenyl ester in the coating)/the content of the polyphenyl ester in the powder, namely the burning loss rate of the polyphenyl ester.

The method for measuring the content of the polyphenyl ester in the coating is as follows: and (3) taking down the coating obtained by spraying by a mechanical method, measuring the weight of the coating, then carrying out heat treatment on the taken-down coating at 450 ℃ for 4h in an air resistance furnace, measuring the weight of the coating, and calculating the weight loss rate of the coating, namely the content of the polyphenyl ester in the coating.

As can be seen from the comparison of fig. 4 and 5, the black component in the coating of example 1 (fig. 4) is polyphenyl ester, the gray component is AlSi alloy, and the black polyphenyl ester is uniformly distributed in the network structure formed by the gray AlSi component, compared to the coating of comparative example 1 (fig. 5) in which a large continuous gray AlSi component exists and does not form a uniform network distribution. In addition, the area of the black part of the coating of example 1 (FIG. 4) is larger, which indicates that the content of the polyphenyl ester component is significantly higher than that of comparative example 1 (FIG. 5).

Example 2a

(1) An alloy powder of NiCrAlY (Ni-26Cr-6Al-0.5Y, i.e. the weight ratio Ni: Cr: Al: Y ═ 1: 26: 6: 0.5) is provided. FIG. 6 shows a scanning electron micrograph (800X) of a NiCrAlY powder. In a visual field, the NiCrAlY powder comprises spheroidal main particles, satellite spheres are attached to the surfaces of the spheroidal main particles, the particle size of the main particles is basically distributed within the range of 20-53 mu m, and the particle size of the satellite spheres is basically distributed within the range of 0.5-14 mu m.

The preparation method of the alloy powder comprises the following steps: putting raw materials of a nickel plate, a chromium plate, an aluminum block and an yttrium block into vacuum atomization equipment in proportion, performing intermediate frequency induction heating, after an alloy liquid is homogenized, performing argon atomization, melting furnace burden with 50kW of power, then heating a melt with 140kW of power, starting atomization when the temperature of the atomized melt is 1580 ℃, wherein the atomization parameters are as follows: the diameter of the discharge spout is 7mm, the pressure of atomizing gas is 4.5MPa, the height of the discharge spout is 40mm, and the width of a circular seam is 0.6 mm. After the atomization is finished, the atomized NiCrAlY powder is collected after the material is cooled, and the powder with the particle size distribution according with the table 2.1 is obtained by adopting airflow classification.

(2) The same polyphenyl ester powder as in example 1 was provided, and the polyphenyl ester powder was placed in a refrigerator and frozen at-20 ℃ for 45 minutes.

(3) Mixing the frozen polyphenyl ester powder and NiCrAlY alloy powder according to a weight ratio of 9:1, placing the mixture in a stainless steel mixing barrel, and connecting the outer side of the stainless steel mixing barrel with the ground through a copper wire with the diameter of 2 mm. A linear stirring paddle with the diameter of 40cm is arranged in the stirring barrel, and the stirring is carried out for 15min at the speed of 30 r/min.

(4) Then adding polyvinyl alcohol binder accounting for 5 percent of the total weight of the powder into a stirring barrel, and stirring for 45min to obtain the AlSi/polyphenyl ester mixed powder.

Table 2.1 shows the powder particle size parameters for NiCrAlY powder, polyphenyl ester powder and NiCrAlY/polyphenyl ester mixed powder.

TABLE 2.1

Example 2b

Example 2b differs from example 2a only in that the polyphenyl ester powder of example 2b is at room temperature, which is not frozen at-20 ℃ for 45 minutes.

Comparative example 2

Comparative example 2 differs from example 2a only in the NiCrAlY powder used. The preparation method of the alloy powder comprises the following steps: putting raw materials of a nickel plate, a chromium plate, an aluminum block and an yttrium block into vacuum atomization equipment in proportion, performing intermediate frequency induction heating, after an alloy liquid is homogenized, performing argon atomization, melting furnace burden with 50kW of power, then heating a melt with 140kW of power, starting atomization when the temperature of the atomized melt is 1580 ℃, wherein the atomization parameters are as follows: the diameter of the discharge spout is 7mm, the height of the discharge spout is 40mm, the pressure of atomizing gas is 2.0MPa, and the width of a circular seam is 0.6 mm. And after the atomization is finished, collecting atomized NiCrAlY powder after the material is cooled, and classifying by adopting air flow to obtain finished powder with the main particle size of 20-53 mu m.

FIG. 7 shows a scanning electron micrograph of a NiCrAlY powder of comparative example 2, in which the powder particles are spherical in shape and the powder surface is substantially free of satellite spheres.

The particle parameters of the NiCrAlY powder of comparative example 2 are shown in table 2.2 below.

TABLE 2.2

Due to the different atomization gas pressures of the vacuum atomization of example 2a and comparative example 2, the powder products have different morphology and particle size characteristics.

Analytical test 2

The powders of examples 2a, 2b and comparative example 2 were sprayed onto a GH4169 nickel base alloy substrate using atmospheric plasma spraying to a thickness of 1.5 mm. Spraying equipment: metco F4 spray gun, spray parameters are shown in table 2.3 below.

TABLE 2.3

The properties of the resulting coating are shown in table 2.4 below. Fig. 8 and 9 show cross-sectional scanning electron micrographs of the coatings of example 2a and comparative example 2, respectively.

TABLE 2.4

Serial number	Powder appearance	Uniformity of coating hardness	Burning loss of polyphenyl ester	Morphology of
					Example 2a	Color uniformity	50～60HR45Y	14％	FIG. 8
Example 2b	The color is more uniform	45～78HR45Y	16％	--
					Comparative example 2	Color unevenness	32～86HR45Y	31％	FIG. 9

As can be seen from the comparison of FIGS. 8 and 9, the black polyphenyl ester component in the coating (FIG. 8) of example 2a has no continuous distribution phenomenon, the gray NiCrAlY component forms better net shape, the coating structure is uniform, and the content of the polyphenyl ester component in the coating is obviously more. In the coating of comparative example 2 (FIG. 9), the black polybenzoate component was continuously agglomerated and the gray NiCrAlY component was continuously agglomerated and layered, and the coating texture was not uniform. In addition, the coating of comparative example 2 (FIG. 9) had significantly less of the polyphenyl ester component than example 2a (FIG. 8).

Based on the comparison between example 2a and comparative example 2a in Table 2.4, it can be seen that freezing treatment of the polyphenyl ester powder can significantly improve the hardness uniformity of the coating and reduce the ablation amount of polyphenyl ester.

In summary, the present disclosure uses metal powders of a particular morphology and particle size distribution to achieve improved coatings despite the broader particle size distribution of the plastic powders used in the present disclosure. In addition, the present disclosure also inventively uses low temperature plastic powders to obtain coatings with further improved properties.

While specific embodiments of the invention have been described in detail, those skilled in the art will understand that: various modifications may be made in the details within the teachings of the disclosure, and these variations are within the scope of the invention. The full scope of the invention is given by the appended claims and any equivalents thereof.

Claims

1. A powder composition comprising a metal powder and a plastic powder;

wherein the metal powder contains spheroidal main particles, and one or more of the main particles are attached with spheroidal satellite spheres on the surface;

wherein the bulk density B, the true density rho and the particle diameters D10, D50 and D90 of the metal powder satisfy the following relational expression (D90-D10)/(D50-D10) (B/rho) ═ 1.0-1.1;

wherein the particle size parameters D10, D50 and D90 of the plastic powder satisfy the following relational expression (D90-D10)/(D50-D10) of 2.0-2.5;

wherein the mass ratio of the plastic powder to the metal powder is 0.1-100: 0.1 to 100;

the metal powder has D10 of 5-40 μm, D50 of 20-50 μm and D90 of 40-70 μm;

the plastic powder has D10 of 8-20 μm, D50 of 55-80 μm and D90 of 110-150 μm;

the bulk density B of the metal powder is 1-4 g/cm³；

The metal powder has a true density rho of 2-10 g/cm³。

2. The powder composition according to claim 1, wherein the particle size of the main particle is 2 times or more the particle size of the satellite.

3. The powder composition according to claim 1, wherein the particle size of the main particle is 5 times or more the particle size of the satellite.

4. The composition of claim 1, having one or more of the following characteristics:

-the metal powder has (D90-110)/(D50-D10) of 2.0 to 2.6;

-the ratio of the bulk density to the true density (B/p) of the metal powder is 0.3 to 0.5;

-the mass ratio of the plastic powder to the metal powder is 0.1-10: 1;

the bulk density B of the plastic powder is 0.3 to 0.8g/cm³；

The true density rho of the plastic powder is 1-2 g/cm³

The ratio (B/p) of the bulk density to the true density of the plastic powder is 0.3 to 0.5.

5. The composition of claim 1, wherein the plastic powder is prepared by a size reduction method.

6. The powder composition of claim 1, having one or more of the following characteristics:

-the metal powder is an aluminium alloy powder;

-the metal powder is a superalloy powder;

-the plastic powder is a polyester powder;

-a binder is also present in the powder composition;

-in said powder composition, a metal powder is homogeneously mixed with a plastic powder.

7. The powder composition of claim 6, having one or more of the following characteristics:

-the metal powder is an AlSi alloy powder;

-said metal powder is a NiCrAlY alloy powder;

-the plastic powder is a polyphenyl ester powder;

-the binder is polyvinyl alcohol

-the content of the binder is 0.1 to 10 wt%.

8. A method of preparing a powder composition comprising the steps of:

providing metal powder, wherein the metal powder contains main particles with a spherical shape, one or more main particles are attached with spherical satellite spheres on the surface, and the loose packing density B, the true density rho and the particle diameters D10, D50 and D90 of the metal powder satisfy the following relational expression (D90-D10)/(D50-D10) (B/rho) ═ 1.0-1.1;

providing a plastic powder satisfying the following relation (D90-D10)/(D50-D10) of 2.0-2.5;

mixing the metal powder and the plastic powder;

the metal powder has D10 of 5-40 μm, D50 of 20-50 μm and D90 of 40-70 μm;

the bulk density B of the metal powder is 1-4 g/cm³；

The metal powder has a true density rho of 2-10 g/cm³；

The step of providing the metal powder has any of the following characteristics:

(1) the metal powder is AlSi alloy powder, the AlSi alloy powder is prepared by adopting a high-pressure airflow atomization method, a metal raw material is heated and melted to form a melt at 800-900 ℃, then the melt flows downwards through a discharge spout and is atomized under the action of high-pressure gas to form the metal powder, and the atomization parameters are as follows: the diameter of the discharge spout is 8-10 mm, the height of the discharge spout is 30-35 mm, the atomizing gas is nitrogen, the pressure of the atomizing gas is 4-5 MPa, a circular seam type nozzle is adopted, and the width of the circular seam is 0.5-0.7 mm; after the atomization is finished, collecting atomized aluminum-silicon powder after the material is cooled, and obtaining metal powder according with the above relational size distribution by adopting airflow classification; or

(2) The metal powder is NiCrAlY alloy powder, and the NiCrAlY alloy powder is prepared by adopting a high-pressure airflow atomization method; heating metal raw materials to melt and form a melt of 1500-1600 ℃, then enabling the melt to flow downwards through a discharge spout, and atomizing the melt under the action of high-pressure gas to form metal powder, wherein the atomization parameters are as follows: the diameter of the discharge spout is 8-10 mm, the height of the discharge spout is 38-42 mm, the pressure of atomizing gas is 4-5 MPa, a circular seam type nozzle is adopted, and the width of a circular seam is 0.5-0.7 mm; and after the atomization is finished, collecting atomized NiCrAlY powder after the material is cooled, and obtaining the metal powder according with the above relational particle size distribution by adopting airflow classification.

9. The method of claim 8, characterized by one or more of the following:

-the temperature of the metal powder provided is-30 ℃ to 30 ℃;

-providing the plastic powder at a temperature of-30 ℃ to 0 ℃.

10. The method of claim 8, wherein the primary particle has a particle size that is 2 times or more the particle size of the satellite.

11. The method of claim 10, wherein the primary particle has a particle size that is more than 2 times the particle size of the satellite.

12. The method of claim 8, having one or more of the following features:

-the metal powder has (D90-D10)/(D50-D10) of 2.0 to 2.6;

the bulk density B of the plastic powder is 0.3 to 0.8g/cm³；

The true density rho of the plastic powder is 1-2 g/cm³

13. The method of claim 8, having one or more of the following features:

-the metal powder is an aluminium alloy powder;

-the metal powder is a superalloy powder;

-the plastic powder is a polyester powder;

-a binder is also present in the powder composition.

14. The method of claim 13, having one or more of the following features:

-the metal powder is an AlSi alloy powder;

-said metal powder is a NiCrAlY alloy powder;

-the plastic powder is a polyphenyl ester powder;

-the binder is polyvinyl alcohol.

15. The method of claim 8, further comprising: a binder is added to the combination of metal powder and plastic powder before or during stirring.

16. The method according to claim 8, characterized in that some one or more of:

-the mixing means that the metal powder and the plastic powder are stirred in a stirring vessel with a stirring paddle, the rotation speed of the stirring paddle is 10-50r/min, and the stirring time is 10-100 min;

-stirring the metal powder and the plastic powder in an electrically conductive stirring vessel, which is electrically connected to earth.

17. A powder composition obtained by the process of any one of claims 8 to 16.

18. A method for forming a thermal spray coating on a substrate surface, comprising performing thermal spraying on the substrate surface using the powder composition according to claim 1 to 7 or 17 as a spraying medium.

19. The method of claim 18, the thermal spraying being plasma spraying.

20. A thermal spray coating obtained by the method of claim 19.