PREPARATION METHOD AND DEVICE OF COMPOSITE COATING FOR RESIN MATRIX COMPOSITE

Abstract

The disclosure discloses a preparation method of a composite coating for a resin matrix composite, comprising the following steps: preparing ceramic-resin composite powders which comprise Al.sub.2O.sub.3 ceramic, a thermosetting resin and a curing agent and are semi-thermosetting resin powders; and respectively spraying pure Al.sub.2O.sub.3 ceramic powders and the composite powders on the surface of the resin matrix composite by supersonic atmospheric plasma spraying to form a ceramic-resin composite coating, wherein the pure Al.sub.2O.sub.3 ceramic powders are fed into jet flow in a manner of feeding powder inside a spray gun, and the composite powders are fed into jet flow in a manner of feeding powder outside the spray gun. Correspondingly, the disclosure also provides a preparation device of a composite coating for a resin matrix composite.

Claims

1. A preparation method of a composite coating for a resin matrix composite, comprising the following steps: preparing ceramic-resin composite powders which comprise Al.sub.2O.sub.3 ceramic, a thermosetting resin and a curing agent, and are semi-thermosetting resin powders; and respectively spraying pure Al.sub.2O.sub.3 ceramic powders and the composite powders on the surface of the resin matrix composite by supersonic atmospheric plasma spraying to form a ceramic-resin composite coating, wherein the pure Al.sub.2O.sub.3 ceramic powders are fed into jet flow in a manner of feeding powder inside a spray gun, and the composite powders are fed into jet flow in a manner of feeding powder outside the spray gun.

2. The preparation method of the composite coating for the resin matrix composite according to claim 1, wherein the preparing ceramic-resin composite powders also comprises the following steps: mixing the Al.sub.2O.sub.3 ceramic, the thermosetting resin and the curing agent, granulating via agglomeration, drying and forming; wherein, a ratio of the Al.sub.2O.sub.3 ceramic to the thermosetting resin to the curing agent is 50.000%: 45.455%: 4.545%, and the thermosetting resin is phenolic resin PF; the curing agent is hexamethylenetetramine; and screening the Al.sub.2O.sub.3 ceramic, the thermosetting resin and the curing agent after being mixed through a powder sieve to obtain the composite powders with a particle size of 0.3-70 .Math.m and a core-shell structure.

3. The preparation method of the composite coating for the resin matrix composite according to claim 1, wherein, the supersonic atmospheric plasma spraying also comprises the following steps: simultaneously spraying the composite powders and the pure Al.sub.2O.sub.3 ceramic powders, and changing an addition amount proportion of each powder so that ceramic and resin components in the composite coating realizes continuous gradient change.

4. The preparation method of the composite coating for the resin matrix composite according to claim 1, wherein, the supersonic atmospheric plasma spraying also comprises the following steps: alternatively spraying the composite powders and the pure Al.sub.2O.sub.3 ceramic powders for many times to form a lasagna type multi-layer structure.

5. The preparation method of the composite coating for the resin matrix composite according to claim 1, wherein, a main spraying gas is argon, and the gas flow of the argon is 58 L•min.sup.-1-62 L•min.sup.-1; a secondary gas is hydrogen, and the gas flow of the hydrogen is 12 L•min.sup.-1-18 L•min.sup.-1; a powder feeding gas is argon, and a spraying distance is 140-160 mm; the pure Al.sub.2O.sub.3 ceramic powders are fed by a first powder feeder, and the composite powders are fed by a second powder feeder; wherein, the pure Al.sub.2O.sub.3 ceramic powder: the powder feeding amount of the composite powder is 3.6: 5.4 g•min.sup.-1-3.6: 20 g•min.sup.-1; a spraying voltage is 90-110 V; a spraying current is 350-450 A; the second powder feeder has an axial distance of 90-110 mm; the temperature of the resin matrix composite is 100-150° C.

6. The preparation method of the composite coating for the resin matrix composite according to claim 5, wherein, the gas flow of the argon is 60 L•min.sup.-1; the gas flow of the hydrogen is 15 L•min.sup.-1; the spraying distance is 150 mm; the pure Al.sub.2O.sub.3 ceramic powder: the powder feeding amount of the composite powder is 3.6: 12 g•min.sup.-1; a spraying voltage is 100 V; a spraying current is 420 A; the second powder feeder has an axial distance of 20-120 mm, a radial distance of 1-12 mm and a jet flow angle of 70-100°; the temperature of the resin matrix composite is 90-150° C.

7. The preparation method of the composite coating for the resin matrix composite according to claim 1, wherein, the surface of the resin matrix composite is subjected to linear reciprocating spraying by using a supersonic atmospheric plasma spray gun, and the movement speed of the spray gun is 40 m/min; the times of the spraying is 50-60 times, and the thickness of the obtained coating is 0.6-0.8 mm.

8. The preparation method of the composite coating for the resin matrix composite according to claim 1, wherein, prior to the supersonic atmospheric plasma spraying, the preparation method also comprises the following steps: pretreating the surface of the resin matrix composite; the pretreating comprises performing washing and sand blasting treatment on the surface of the resin matrix composite.

9. The preparation method of the composite coating for the resin matrix composite according to claim 8, wherein, the pretreating comprises: washing the surface of the matrix with ethyl alcohol or acetone; a sand blasting material selects brown aluminum oxide with a particle size of 120-180 .Math.m, a sand blasting atmospheric pressure of 0.3 ± 0.05 MPa and a sand blasting angle of 70 ± 10°, a distance between the spray gun and the surface of the resin matrix composite is 100-150 .Math.m, and the sand blasting time is once for flat sweeping.

10. A preparation device of a composite coating for a resin matrix composite for implementing the method according to claim 1.

Description

DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1 is a structural diagram of a double-layer structural coating of “metal transition layer + ceramic surface layer” in the prior art;

[0036] FIG. 2 is a schematic diagram showing uniform distribution of components in composite powders according to the disclosure;

[0037] FIG. 3 is a schematic diagram of a core-shell structure of components in composite powders according to the disclosure;

[0038] FIG. 4 is a schematic diagram of a powder feeding position close to a nozzle during the spraying in the prior art;

[0039] FIG. 5 is a schematic diagram of a powder feeding position close to a matrix during the spraying according to the present invention;

[0040] FIG. 6 is a schematic diagram showing parameters of a spray gun according to the disclosure;

[0041] FIG. 7 is a schematic diagram of a continuous gradient structure of a composite coating according to the disclosure;

[0042] FIG. 8 is a schematic diagram of a lasagna structure of a composite coating according to the disclosure;

[0043] FIG. 9 is a process flow chart according to the disclosure;

[0044] FIG. 10 is a particle size distribution diagram of Al,O.sub.3-PF composite powders used in the disclosure;

[0045] FIG. 11 is a flat pattern of a composite coating prepared in example 2 according to the disclosure;

[0046] FIG. 12 is a graph showing XRD and FTIR test results of a composite coating;

[0047] FIG. 13 is a graph showing SEM morphology of a composite coating before and after ablation;

[0048] FIG. 14 is a morphology graph of an elastic modulus test indentations of a composite coating;

[0049] FIG. 15 shows thermal conductivities of pure Al.sub.2O.sub.3 powders and Al.sub.2O.sub.3-PF composite powders in different ratios;

[0050] FIG. 16 shows thermal expansion coefficients of pure Al.sub.2O.sub.3 powders and Al.sub.2O.sub.3-PF composite powders in different ratios.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0051] Next, the disclosure will be further described in detail in combination with accompanying drawings, so that those skilled in the art can implement it with reference to the words in the specification.

[0052] A thermal spray coating preparation technology can adopt atmospheric plasma spraying (APS), flame spraying, supersonic atmospheric plasma spraying (SAPS), etc.

[0053] In the spraying process of atmospheric plasma jet flow, continuous overlapping and stacking is performed between particles so as to form the coating, and therefore pores are easily produced. Moreover, two or more than two materials can be simultaneously sprayed by sufficiently utilizing the characteristic of temperature gradient of plasma jet flow to form the composite coating. The defects such as pores and microcracks in the coating are important criteria to evaluate the quality of the coating, but it is also found that appropriate pores and microcracks existing in the coating can improve the heat resistance of the coating. For a heat-resistant coating, it needs to have both good heat resistance and good bonding strength. Generally, the bonding strength can be tested by a universal tensile testing machine. For the heat resistance of the coating, the thermal conductivity and the thermal expansion coefficient of the coating can be measured by laser heat conduction.

[0054] In addition, the resin matrix composite belongs to a polymer material, which often has a heat resistance temperature, and therefore a method for preparing a protective coating on the surface of the resin matrix composite (also called the matrix) is generally a low-heat-source coating preparation method such as flame spraying, cold spraying and solution-gel spraying.

[0055] The following three solutions are explored for the feasibility of preparing a ceramic protective coating on the surface of the resin matrix composite by using an atmospheric plasma spraying (APS) technology: solution 1 is to prepare a double-layer structure coating of “metal transition layer + ceramic surface layer” by using low-melting-point metals such as Al and Zn, as shown in FIG. 1; solution 2 is to prepare composite coatings containing two or more than two ceramic coatings; solution 3 is to prepare a ceramic coating with gradient change. The coatings prepared by these three solutions can provide a certain protection such as heat resistance and ablation resistance for the resin matrix composite, but there are still deficiencies that 1, the introduction of a metal transition layer reduces the reliability of corrosion resistance and insulation of the composite; 2, the coating has a low bonding strength (generally about 10 MPa); 3, the thermal expansion coefficients of the coating and the matrix is quite different. Compared with ordinary atmospheric plasma spraying (APS), supersonic atmospheric plasma spraying (SAPS) has higher heat source temperature and jet velocity, so it is generally considered that it is not feasible to prepare the ceramic coating on the surface of the resin matrix composite by supersonic atmospheric plasma spraying (SAPS).

[0056] However, the disclosure overcomes the above technical bias and provides a preparation method of a composite coating of a resin matrix composite, which is specifically described as follows:

1. Preparation of Ceramic-Resin Composite Powder

[0057] (1) The composite powder can be in two forms, namely, uniform distribution of ceramics and resins in a single particle (FIG. 2); the single particle is a ceramic coated resin, forming a “shell-core” structure (FIG. 3).

[0058] (2) In particular, the resin in the composite powder is a thermosetting resin, and the prepared composite powder is a semi-thermosetting composite powder. The ceramic material used in the disclosure is Al.sub.2O.sub.3 ceramic, and the thermosetting resin used is phenolic resin (PF), but not limited to the above ceramics and resin materials.

[0059] Because the resin used in the composite powder in the disclosure is the thermoplastic resin PF and a certain curing agent is added, the curing reaction will begin to occur when being heated at 150° C., so the prepared composite powder is the semi-thermosetting composite powder. This composite powder can not only slow down the thermal expansion difference between the coating and the matrix and greatly improve the bonding strength between the coating and the matrix, but also avoid the introduction of conductive materials so as to improve the reliability of the resin matrix composite in the field of insulation.

[0060] In particular, the ceramic particles in the outer layer of the composite powder with a “core-shell” structure can greatly keep the inner core resin not to be decomposed. The synchronous melting of ceramics and resin can be realized through the heat transfer of the ceramic, which is crucial to improvement of the quality of coating.

2. The Composite Powder is Sprayed by Supersonic Atmospheric Plasma Spraying SAPS

[0061] Through experiments, it is verified that the preparation of the coating by using thermal spray coating preparation technologies such as atmospheric plasma spraying, flame spraying and supersonic atmospheric plasma spraying (SAPS) cannot avoid the thermal decomposition of the resin in the semi-setting composite powder. However, it is found that the coating with excellent quality can be prepared by spraying the semi-setting composite powder only with the SAPS technology. The coating with excellent quality cannot be prepared by using other spraying methods or other forms of composite powders. The analysis shows that: (1) because SAPS has a high heat source and has temperature gradient, and therefore can make the ceramic particles fully melted and meanwhile shorten the heating time and heating distance to facilitate the synchronous melting of ceramics and resin; (2) because SAPS has a higher jet velocity, in the process of preparing the coating, on the one hand, the sufficiently melted particles can more sufficiently spread after impacting the matrix; on the one hand, the sufficiently molten particles can impact the matrix at a high kinetic energy so as to be flattened and increase the bonding strengths between particles and between the coating and the matrix.

3. The Disclosure Adopts a “Double-Channel and Double-Temperature-Zone” Powder Feeding Technology

[0062] “Double-channel double-temperature-zone” powder feeding refers to feeding spraying powders into jet flow zones at different temperatures, which has the advantages that (1) a variety of spraying feed materials are synchronously melted; (2) the composite coating containing various components can be prepared; (3) the coating with continuous gradient change in components can be prepared.

[0063] In the atmospheric plasma spraying (APS), the “double-channel double-temperature-zone” powder feeding technology is often used. The position of the second powder feeder is close to the outlet of the nozzle, which is as shown by the spraying powder 2 as shown in FIG. 4, to obtain the higher heat source temperature; however, it is required in the disclosure that the position of the second powder feeder is close to the matrix, which is as shown in the spraying powder 2 in FIG. 5. Through the experiment, it is verified that in the process of preparing the coating in the disclosure, if the position of the second powder feeder is close to the nozzle as shown in FIG. 4, the quality of the final coating will be greatly reduced. Since the melting point of the pure Al.sub.2O.sub.3 ceramic is about 2050° C., the pure Al.sub.2O.sub.3 powders, as the spraying powder 1 shown in FIG. 5, are fed in a manner of feeding the powder inside the spray gun and have an ideal melting degree and a flight speed under the action of high-temperature high-speed plasma jet flow. The Al.sub.2O.sub.3-PF composite powders, as the spraying powder 2 in FIG. 5, are fed in a manner of feeding the powder outside the spray gun, are in a “low-temperature zone”, thus the Al.sub.2O.sub.3 in the composite powder is insufficient melted, but the PF resin is kept by Al.sub.2O.sub.3 as much as possible and well melted, so as to form a coating structure with Al.sub.2O.sub.3 as the skeleton and filled with the PF resin, thereby improving the heat resistance and bonding strength of the coating.

4. Powder Feeding

[0064] In the disclosure, the spraying powder for preparing the coating is not only the prepared ceramic resin composite powder but also the pure ceramic powder. The specific method is as follows: the pure ceramic powders are fed into the spray gun in a manner of feeding the powder inside the spray gun; the ceramic-resin composite powders are fed into jet flow in a manner of feeding the powder outside the spray gun.

[0065] In the process of spraying: (1) the pure ceramic powders and the composite powders can be simultaneously added, and the addition amount of each powder can be changed so that the coating component realizes continuous gradient change, as shown in FIG. 7; (2) each powder can be sprayed in turn, that is, the pure ceramic powders are sprayed once or several times, and then the composite powders are sprayed once or several times, so as to form a coating with a “lasagna” structure, as shown in FIG. 8.

5. Key Parameters for Coating Preparation

[0066] In the disclosure, the key parameters include: powder spraying, matrix pretreatment, spraying voltage, spraying current, spraying distance, second powder feeding distance, second powder feeding angle, matrix temperature, powder feeding proportion and gas flow.

[0067] Innovation description: the disclosure explores the optimization parameters of SAPS spraying of the ceramic-resin composite coating on the surface of the resin matrix composite. Combined with the process flow chart of FIG. 8, the details are described as follows: [0068] (1) Preparation of composite powder: A1.sub.2O.sub.3, thermosetting PF and hexamethylenetetramine (a curing agent) are mixed, granulated via agglomeration, dried and formed to prepare the Al.sub.2O.sub.3-PF composite powder with a particle size of 0.3-70 .Math.m, as shown in FIG. 10; [0069] (2) pretreatment of surface of matrix; [0070] (3) spraying of the Al.sub.2O.sub.3-PF composite coating: spraying with an atmospheric plasma spray gun, and the spraying parameters are as follows: a main spraying gas is argon, and the gas flow is 58 L•min-1-621•min.sup.-1; a secondary gas is hydrogen, and the gas flow is 12 L • min.sup.-1-181 • min.sup.-1; a powder feeding gas is argon, and a spraying distance is 140-160 mm; the powder feeding amount of the two spraying feed materials is pure A1.sub.2O.sub.3: the composite powder being 3.6:5.4 g•min.sup.-1-3.6:20 g•min.sup.-1; a spraying voltage is 90-110 V; a spraying current is 350-450 A; the second powder feeder has an axial distance a of 20-120 mm, a radial distance r of 1-12 mm, and a jet angle θ of 70-100 °, wherein, as shown in FIG. 6, the axis refers to the central axis of the spray gun or the spray gun axis, the axial distance a is a distance from the nozzle of the second powder feeder to the outlet of the spray gun along the spray gun axis, and the radial distance r is a vertical distance from the nozzle of the second powder feeder to the spray gun axis and the jet angle θ is an inclined angle of the second powder feeder relative to the spray gun axis; the spraying temperature of the resin matrix composite is 90-150° C. The spraying Al.sub.2O.sub.3-PF composite coating in the disclosure can also be called a spraying “dry” coating. [0076] (4) The Al.sub.2O.sub.3-PF composite coating is prepared and undergoes coating performance test verification: the X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectra of the coating show that the phase group compositions of the coating are Al.sub.2O.sub.3 phase and PF, as shown in FIG. 12.

[0071] In addition, FIG. 13 is a graph showing scanning electron microscope (SEM) morphology of a composite coating of the disclosure before and after ablation, and FIG. 14 is a graph showing elastic modulus test indentation morphology of a composite coating of the disclosure.

[0072] Preferably, step (1) in the method for preparing the Al.sub.2O.sub.3-PF composite coating is as follows: [0073] (1-1) Al.sub.2O.sub.3, thermosetting PF and hexamethylenetetramine (a curing agent) are mixed, granulated via agglomeration, dried and formed; the powder comprises 50.000% of Al.sub.2O.sub.3, 45.455% of PF and 4.545% of hexamethylenetetramine (proportions are calculated based on a separate ratio of the thermosetting resin to the curing agent, that is, 1000 kg of thermosetting resin requires 100 kg of curing agent); [0074] (1-2) the composite powders are screened through a 100-mesh powder sieve to obtain the composite powder with a particle size of 0.3-70 .Math.m, as shown in FIG. 10. [0081] Preferably, step (2) in the method for preparing the Al.sub.2O.sub.3-PF composite coating is as follows: [0075] (2-1) the surface of the matrix surface is washed with alcohol or acetone to remove oil stains on the surface of the matrix; [0076] (2-2) sand blasting treatment is performed on the surface of the matrix. The sand blasting material is brown corundum with a particle size of 120-180 .Math.m, a sand blasting pressure of 0.3 ± 0.05 Mpa, a distance between the spray gun and the surface of the resin matrix composite is 100-150 .Math.m, and the sand blasting time is once for flat sweeping (about 1-2 s).

[0077] Preferably, step (3) in the method for preparing the Al.sub.2O.sub.3-PF composite coating is as follows: [0078] (3-1) under the spraying parameters, the surface of a workpiece is sprayed with a supersonic atmospheric plasma spray gun. The “linear reciprocating” spraying method is adopted in the spraying process, and the moving speed of the spray gun is 40 m/min; [0079] (3-2) the spraying times are 50-60 times, and the thickness of the obtained coating is about 0.6-0.8 mm (in which 0.8 mm is the thickness required for lathe grinding);

[0080] More preferably, the spraying parameters in step (3) are as follows: a main spraying gas is argon and the gas flow is 60 L•min.sup.-1; a secondary gas is hydrogen, and the gas flow is 15 L•min.sup.-1; a powder feeding gas is argon, and a spraying distance is 150 mm; the powder feeding amount of the two spraying feed materials is pure A1.sub.2O.sub.3: the composite powder is 3.6:12 g•min.sup.-1; a spraying voltage is 100 V; a spraying current is 420 A; the second powder feeder has an axial distance a of 100 mm, a radial distance r of 2.5 mm, and a jet angle θ of 90°, and the temperature of the matrix is 120° C. The test of the more preferred embodiment can be seen in embodiment 2 and FIG. 11 below.

[0081] Preferably, step (4) in the method for preparing Al.sub.2O.sub.3-PF composite coating is as follows: [0082] (4-1) the melting point of pure Al.sub.2O.sub.3 is about 2050° C., so the pure Al.sub.2O.sub.3 powders are fed in a manner of feeding the powder inside the spray gun, and melted and obtains a flight speed in high-temperature high-speed plasma jet flow; the Al.sub.2O.sub.3-PF composite powders are fed in a manner of feeding the powder outside the spray gun and are fed in a “low-temperature zone” so as to ensure that the PF resin is melted, but not decomposed by heating; [0083] (4-2) in the process of spraying, the pure Al.sub.2O.sub.3 and the Al.sub.2O.sub.3-PF composite powders are sprayed once respectively in a manner of alternately spraying; [0084] (4-3) the pure Al.sub.2O.sub.3 powders have an ideal melting degree and a flight speed under the action of high-temperature high-speed plasma jet flow. The Al.sub.2O.sub.3-PF composite powders are in a “low-temperature zone”, thus the Al.sub.2O.sub.3 in the composite powder is insufficient melted, but the PF resin is kept by Al.sub.2O.sub.3 as much as possible and well melted, so as to form a coating structure with Al.sub.2O.sub.3 as the skeleton and filled with the PF resin, thereby improving the heat resistance and bonding strength of the coating.

[0085] Correspondingly, the disclosure also provides a preparation device of a composite coating for a resin matrix composite for implementing each step in the previous preparation method, that is, the preparation device can include, but is not limited to, a spray granulating device for preparing the composite powder of the disclosure, a powder sieve, a device for pretreatment of a matrix, and an exemplary SAPS spraying device shown in FIG. 5. It can be understood that in order to perform any step of the previous preparation method, the disclosure does not limit the compositions and structures of the sub device or sub components of the preparation device.

[0086] The following examples all use the same Al.sub.2O.sub.3-PF composite powder, matrix surface pretreatment and optimized spraying parameters, but the proportions of the powder feeding amounts of the pure Al.sub.2O.sub.3 in the first powder feeder and the Al.sub.2O.sub.3-PF composite powder in the second powder feeder in different embodiments are different. FIG. 15 shows the thermal conductivities of the pure Al.sub.2O.sub.3 powder and the Al.sub.2O.sub.3-PF composite powder in different ratios, and FIG. 16 shows the thermal expansion coefficients of the pure Al.sub.2O.sub.3 powder and the Al.sub.2O.sub.3-PF composite powder in different ratios.

Example 1

[0087] Under the condition that the above process parameters are adopted:

[0088] ST1 process is as follows: a ratio of spraying pure Al.sub.2O.sub.3 to Al.sub.2O.sub.3-PF composite powder is 3.6:5.4 g/min. Table 1 and Table 2 show heat resistance and mechanical properties of a coating prepared by the ST1 process, respectively.

TABLE-US-00001 Heat resistance of coating prepared by ST1 process Process Heat conductivity (W/(m*K)) Thermal expansion coefficient (1/K) 100° C. 200° C. 25-100° C. 25-200° C. 100° C. Transient 200° C. Transient ST1 0.338 0.357 24.529*10.sup.-6 35.762*10.sup.-6 2.545*10.sup.-5 7.141*10.sup.-5 Resin matrix - - 10.498*10.sup.-6 13.014*10.sup.-6 1.206*10.sup.-5 1.895*10.sup.-5

TABLE-US-00002 Mechanical properties of coating prepared by ST1 process Process Al.sub.2O.sub.3:Al.sub.2O.sub.3-PF(g/min) Elasticity modulus/GPa Bonding strength/MPa Shear strength/MPa ST1 3.6:5.4 20.147 10.397 6.562

[0089] From the data in Table 1 and Table 2, it can be seen that the ceramic resin-composite coating prepared by the ST1 process has a good heat insulation ability and a low thermal conductivity, and has a bonding strength of 10.397 MPa.

Example 2

[0090] Under the condition that the above process parameters are adopted:

[0091] ST1 process is as follows: a ratio of spraying pure Al.sub.2O.sub.3 to Al.sub.2O.sub.3-PF composite powder is 3.6:12.0 g/min. As shown in FIG. 11, it shows manifestation of the Al.sub.2O.sub.3-PF composite coating prepared in this ratio. Table 3 and Table 4 show heat resistance and mechanical properties of a coating prepared by the ST1 process, respectively.

TABLE-US-00003 Heat resistance of coating prepared by ST2 process Process Heat conductivity (W/(m*K)) Thermal expansion coefficient (1/K) 100° C. 200° C. 25-100° C. 25-200° C. 100° C.Tran sient 200° C.Trans ient ST2 Resin matrix 0.315 0.328 19.619*10.sup.-6 28.828*10.sup.-6 2 .270*10.sup.-5 4.933*10.sup.-5 ____ ____ 10.498*10.sup.-6 13.014*10.sup.-6 1.206*10.sup.-5 1.895*10.sup.-5

TABLE-US-00004 Mechanical properties of coating prepared by ST2 process Process Al.sub.2O.sub.3:Al.sub.2O.sub.3-PF(g/min) Elasticity modulus/GPa Bonding strength/MPa Shear strength/MPa ST2 3.6:12.0 27.604 26.035 15.867

[0092] From the data in Table 3 and Table 4, it can be seen that the ceramic resin-composite coating prepared by the ST2 process has a good heat insulation ability and a low thermal conductivity, and has a bonding strength of 26.035 MPa.

Example 3

[0093] Under the condition that the above process parameters are adopted:

[0094] ST3 process is as follows: a ratio of spraying pure Al.sub.2O.sub.3 to Al.sub.2O.sub.3-PF composite powder is 3.6:14.2 g/min. Table 5 and Table 6 show heat resistance and mechanical properties of a coating prepared by the ST3 process, respectively.

TABLE-US-00005 Heat resistance of coating prepared by ST3 process Process Heat conductivity (W/(m*K)) Thermal expansion coefficient (1/K) 100° C. 200° C. 25-100° C. 25-200° C. 100° C.Tran sient 200° C.Trans ient ST3 0.346 0.328 19.619*10.sup.-6 28.828*10.sup.-6 2.270*10.sup.-5 4.933*10-.sup.5 Resin matrix 10.498*10.sup.-6 13.014*10.sup.-6 1.206*10.sup.-5 1.895*10.sup.-5

TABLE-US-00006 Mechanical properties of coating prepared by ST3 process Process Al.sub.2O.sub.3:Al.sub.2O.sub.3-PF (g/min) Elasticity modulus/GPa Bonding strength/MPa Shear strength/MPa ST3 3.6:14.2 28.730 24.673 14.352

[0095] From the data in Table 5 and Table 6, it can be seen that the ceramic resin-composite coating prepared by the ST3 process has a good heat insulation ability and a low thermal conductivity, and has a bonding strength of 24.673 MPa.

Example 4

[0096] Under the condition that the above process parameters are adopted:

[0097] ST4 process is as follows: a ratio of spraying pure Al.sub.2O.sub.3 to Al.sub.2O.sub.3-PF composite powder is 3.6:32.4 g/min. Table 7 and Table 8 show heat resistance and mechanical properties of a coating prepared by the ST4 process, respectively.

TABLE-US-00007 Heat resistance of coating prepared by ST4 process Process Heat conductivity (W/(m*K)) Thermal expansion coefficient (1/K) 100° C. 200° C. 25-100° C. 25-200° C. 100° C.Tran sient 200° C.Trans ient ST3 0.346 0.328 19.619*10.sup.-6 28.828*10.sup.-6 2 .270*10.sup.-5 4.933*10.sup.-5 Resin matrix - - 10.498*10.sup.-6 13.014*10.sup.-6 1.206*10.sup.-5 1.895*10.sup.-5

TABLE-US-00008 Mechanical properties of coating prepared by ST4 process Process Al.sub.2O.sub.3:Al.sub.2O.sub.3-PF (g/min) Elasticity modulus/GPa Bonding strength/MPa Shear strength/MPa ST3 3.6:14.2 28.730 24.673 14.352

[0098] From the data in Table 7 and Table 8, it can be seen that the ceramic resin-composite coating prepared by the ST4 process has a good heat insulation ability and a low thermal conductivity, and has a bonding strength of 17.018 MPa.

[0099] Comparisons of corresponding performance test results of four Al.sub.2O.sub.3-PF composite coatings prepared by the above four processes are as shown in Table 9 and Table 10.

TABLE-US-00009 Effect of proportion change of Al.sub.2O.sub.3 and Al.sub.2O.sub.3-PF composite powder on heat resistance of coating Proc ess Al.sub.2O.sub.3:Al.sub.2O.sub.3-PF (g/min) Heat conductivity (W/(m*K)) Thermal expansion coefficient (1/K) 100° C. 200° C. 25-100° C. 25-200° C. 100° C.Tran sient 200° C.Trans ient ST1 3.6:5.4 0.338 0.357 24.529*10.sup.-6 35.762*10.sup.-6 2.545*10.sup.-5 7.141*10.sup.-5 ST2 3.6:12.0 0.315 0.328 19.619*10.sup.-6 28.828*10.sup.-6 2.270*10.sup.-5 4.933*10.sup.-5 ST3 3.6:14.2 0.346 0.377 21.989*10.sup.-6 33.923*10.sup.-6 1.852*10.sup.-5 9.575*10.sup.-5 ST4 3.6:32.4 0.347 0.361 29.315*10.sup.-6 64.996*10.sup.-6 3.899*10.sup.-5 3.828*10.sup.-5 Resin matrix - - 10.498*10.sup.-6 13.014*10.sup.-6 1.206*10.sup.-5 1.895*10.sup.-5

[0100] By changing the proportions of pure Al.sub.2O.sub.3 and Al.sub.2O.sub.3-PF composite powder during the spraying, the content of Al.sub.2O.sub.3 in the coating is changed, and the obtained that there are significant differences in the thermal properties of different coatings. Among them, the composite coating prepared by the ST2 process has the lowest thermal conductivity and thermal expansion coefficient, which is closest to a thermal expansion curve of a resin matrix material, as shown in FIG. 16.

TABLE-US-00010 Effect of proportion change of Al.sub.2O.sub.3 and Al.sub.2O.sub.3-PF composite powder on mechanical properties of coating Process Al.sub.2O.sub.3:Al.sub.2O.sub.3-PF (g/min) Elasticity modulus/GPa Bonding strength/MPa Shear strength/MPa ST1 3.6:5.4 20.147 10.397 6.562 ST2 3.6:12.0 27.604 26.035 15.867 ST3 3.6:14.2 28.730 24.673 14.352 ST4 3.6:32.4 30.269 17.018 13.320

[0101] By changing the proportion of pure Al.sub.2O.sub.3 and Al.sub.2O.sub.3-PF composite powder during the spraying, the content of Al.sub.2O.sub.3 in the coating is changed. There are obvious differences in the thermal properties of different coatings. Among them, the composite coating prepared by the ST2 process has the highest elastic modulus, bonding strength and shear strength. FIG. 14 is a graph showing the micron indentation morphology of the composite coating prepared by the ST2 process.

[0102] Although the embodiment of the disclosure has been disclosed as above, it is not limited to the applications listed in the description and embodiments. It can be fully applicable to various fields suitable for the disclosure. For those familiar with the art, other modifications can be easily realized. Therefore, the disclosure is not limited to specific details and the illustrations shown and described here without departing from the general concepts defined by the claims and equivalent scope.