Ceramic-based composite material surface coating reinforced bonding method based on laser ablation multi-scale physicochemical microstructure

Abstract

The invention discloses a ceramic-based composite material surface coating strengthening and bonding method based on a laser ablation multi-scale physical and chemical microstructure, which comprises the following steps: (1) scanning on the surface of a ceramic-based composite material in a cross manner by using laser, and forming a multi-scale physical microstructure on a laser ablation surface; (2) the ceramic-based composite material ablated by the laser generates gas-phase SiO2 through a chemical reaction, the gas-phase SiO2 captures liquid drops, then the liquid drops flow into pores in the ceramic-based composite material through a tubular channel in a net-shaped ablation groove, and a functional surface with super hydrophilicity is obtained; and (3) preparing a coating on the surface of the ceramic-based composite material subjected to laser ablation. According to the method, the wettability of the ceramic-based composite material is remarkably improved, a functional surface with super hydrophilicity is obtained, and the bonding strength of the ceramic-based composite material and a coating is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of coating preparation, and in particular relates to a method for strengthening bonding of surface coating of ceramic-based composite materials based on laser ablation of multi-scale physical and chemical microstructures. Background Art

[0002] Ceramic matrix composites (CMCs) have become promising materials in aerospace, rail transit, and nuclear power due to their excellent physical properties, including high temperature resistance, mechanical strength, oxidation resistance, corrosion resistance, and low density. To cope with extreme service environments, CMC parts are covered with a uniform coating on the surface after machining to improve their thermal shock resistance, aerodynamic properties, and wear resistance. Therefore, the affinity of the CMC surface to the coating is crucial, which directly affects the service performance and service life of the coating.

[0003] Ceramic-based composites need to serve in extremely high temperature and high pressure working environments, but the lack of affinity between the material and the coating often leads to cracking or falling off. In the coating preparation process, the hydrophilic surface can be more conducive to the adsorption and bonding of the coating material, making the formed coating interface more firmly bonded. Therefore, preparing a super-hydrophilic surface on ceramic-based composites is more important than improving the processing quality. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a method for strengthening the bonding of ceramic-based composite surface coatings based on laser ablation of multi-scale physical and chemical microstructures, to manufacture a super-hydrophilic microstructure on the surface of the ceramic-based composite material, and to improve the bonding strength of the coating.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention discloses a method for strengthening bonding of a surface coating of a ceramic-based composite material based on laser ablation of a multi-scale physical and chemical microstructure, comprising the following steps:

[0007] (1) Using laser to scan the surface of ceramic matrix composite material in a cross manner, a multi-scale physical microstructure is formed on the laser ablation surface; the multi-scale physical microstructure includes a mesh ablation groove, carbon fibers in the mesh ablation groove are sublimated to form tubular channels, convex plate arrays are formed between the mesh ablation grooves, and ablation products of agglomerates composed of nanoparticles are formed on the convex plate array;

[0008] (2) The laser-ablated ceramic matrix composite material produces gas-phase SiO2 through chemical reaction, which captures the droplets and then flows into the pores in the ceramic matrix composite material through the tubular channels in the mesh ablation groove, thereby obtaining a functional surface with super-hydrophilicity.

[0009] (3) Prepare coatings on the surface of ceramic-based composite materials after laser ablation.

[0010] As a preferred technical solution, in step (1), the laser power is set at 4-10 W, the scanning distance is set at 50-110 μm, and the scanning speed is set at 500 mm / min.

[0011] As a preferred technical solution, in step (1), the laser is a picosecond laser.

[0012] As a preferred technical solution, in step (1), the width of the convex plate array is 20-50 μm, the particle size of the ablation product of the agglomerate is 1-10 μm, and the particle size of the nanoparticles is 200-400 nm.

[0013] As a preferred technical solution, in step (2), the reason why the gas-phase SiO2 captures the droplets is that the Si-O bonds of the gas-phase SiO2 absorb hydrogen atoms to form highly hydrophilic hydroxyl groups, which adsorb water and dissolve in water.

[0014] As a preferred technical solution, in step (3), a coating is prepared on the surface of the ceramic-based composite material after laser ablation by plasma spraying technology.

[0015] As a preferred technical solution, the ceramic-based composite material uses silicon carbide as a ceramic matrix and carbon fibers as reinforcing fibers.

[0016] The beneficial effects of the present invention are:

[0017] The present invention utilizes laser to process a multi-scale physical microstructure on the surface of a ceramic-based composite material. The multi-scale physical microstructure significantly improves the wettability of the ceramic-based composite material, and at the same time provides a channel for the adsorption and penetration of water, so that the material surface can quickly absorb water droplets, thereby obtaining a functional surface with super hydrophilicity, and significantly improving the bonding strength between the ceramic-based composite material and the coating.

[0018] In addition, this superhydrophilic surface is achieved through both physical and chemical effects, and no thermal cracks caused by laser ablation are observed. This method causes less damage to the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0020] Figure 1 It is a schematic diagram of using laser to ablate the surface of a ceramic-based composite material; in the figure: control system 1, laser generator 2, attenuator 3, shutter 4, beam expander 5, reflector 6, focusing lens 7, platform 8.

[0021] Figure 2 SEM image of the microstructure after laser ablation.

[0022] Figure 3 Schematic diagram of the multi-scale physical microstructure obtained after laser ablation.

[0023] Figure 4 Schematic diagram of a superhydrophilic functional surface.

[0024] Figure 5 These are the droplet adsorption test results on the surface of ceramic matrix composites without processing and after laser ablation under different laser power conditions.

[0025] Figure 6 Droplet adsorption test results on the vertical surface of the unprocessed and laser ablated ceramic matrix composite.

[0026] Figure 7 These are the droplet adsorption test results on the surface of ceramic matrix composites after laser ablation under different scanning spacing conditions. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0028] The methods used in the following examples are all conventional methods unless otherwise specified. The materials or reagents required in the following examples are all purchased from the market unless otherwise specified.

[0029] Embodiment 1:

[0030] The present embodiment provides a method for strengthening bonding of a ceramic matrix composite material surface coating based on laser ablation of a multi-scale physical and chemical microstructure, comprising the following steps:

[0031] (1) Use Figure 1 The equipment shown sets the laser power at 4W, 6W, and 10W, respectively, sets the scanning distance at 70μm, and the scanning speed at 500mm / min, and uses a picosecond laser to scan the surface of the ceramic matrix composite material in a cross manner to form a multi-scale physical microstructure on the laser ablation surface;

[0032] Multiscale physical microstructures such as Figure 2 and Figure 3 As shown, it includes a mesh ablation groove, the carbon fibers in the mesh ablation groove are sublimated to form a tubular channel, a convex plate array is formed between the mesh ablation grooves, and the convex plate array is composed of nanoparticles to form agglomerate ablation products; the width of the convex plate array is 20-50μm, the particle size of the agglomerate ablation product is 1-10μm, and the particle size of the nanoparticles is 200-400nm;

[0033] (2) The laser-ablated ceramic matrix composite material produces gas-phase SiO2 through chemical reaction; Figure 4 As shown, the surface of gas-phase SiO2 has siloxane groups and Si-O bonds. Si-O bonds strongly absorb hydrogen atoms and easily form highly hydrophilic hydroxyl groups (i.e. -OH), which have strong adsorption to water. Therefore, gas-phase SiO2 captures droplets and then flows into the pores in the ceramic-based composite material through the tubular channels in the mesh ablation groove, thereby obtaining a functional surface with super-hydrophilicity.

[0034] (3) The coating is prepared on the surface of the ceramic-based composite material after laser ablation by plasma spraying technology.

[0035] The contact angle of the ceramic-based composite material after laser ablation with different process parameters in Example 1 was measured: the ceramic-based composite material was placed on the horizontal lifting platform of the equipment, the platform was adjusted to gradually approach the stationary water droplet until it contacted the water droplet, and the changes in the droplet at the moment of contact were recorded.

[0036] Figure 5 The results of droplet adsorption test on the surface of unprocessed and laser-ablated ceramic matrix composites under different laser power conditions. As can be seen from the figure, when the droplet contacts the unprocessed ceramic matrix composite surface, it remains attached to the dropper and the shape does not change significantly. When the unprocessed ceramic matrix composite is separated from the droplet, the droplet completely falls on the surface of the ceramic matrix composite and maintains a stable shape, indicating that the unprocessed ceramic matrix composite (i.e., the initial surface) is hydrophobic. However, when the surface of the ceramic matrix composite after laser ablation with laser powers of 4W, 6W, and 10W and a scanning interval of 70μm contacts the water droplet, the droplet quickly adheres to the surface and disappears immediately. The time it takes for the droplet to disappear shortens as the laser power increases from 4W to 10W.

[0037] In order to avoid the penetration of the droplets into the CMC being affected by their own gravity, another comparative test was conducted: the surface of the CMC was placed perpendicular to the ground and the surface was gradually moved closer to the suspended droplets. Figure 6 The results of droplet adsorption tests on the vertical surfaces of unprocessed and laser-ablated ceramic matrix composites. As can be seen from the figure, the droplet does not change significantly after long-term contact with the unprocessed surface, and when the ceramic matrix composite is separated from the droplet, it hovers on its surface. However, when the droplet contacts the laser-ablated surface, the droplet adheres to the surface and disappears quickly. This result shows that the absorption of the droplet by the laser-ablated surface is not due to gravity.

[0038] Embodiment 2:

[0039] The present embodiment provides a method for strengthening bonding of a ceramic matrix composite material surface coating based on laser ablation of a multi-scale physical and chemical microstructure, comprising the following steps:

[0040] (1) Use Figure 1 The device shown sets the laser power at 8W, sets the scanning distances at 50μm, 70μm, 90μm, and 110μm, respectively, and the scanning speed at 500mm / min. The picosecond laser is used to scan the surface of the ceramic matrix composite material in a cross manner to form a multi-scale physical microstructure on the laser ablation surface;

[0041] Multiscale physical microstructures such as Figure 2 and Figure 3 As shown, it includes a mesh ablation groove, the carbon fibers in the mesh ablation groove are sublimated to form a tubular channel, a convex plate array is formed between the mesh ablation grooves, and the convex plate array is composed of nanoparticles to form agglomerate ablation products; the width of the convex plate array is 20-50μm, the particle size of the agglomerate ablation product is 1-10μm, and the particle size of the nanoparticles is 200-400nm;

[0042] (2) The laser-ablated ceramic matrix composite material produces gas-phase SiO2 through chemical reaction; Figure 4 As shown, the surface of gas-phase SiO2 has siloxane groups and Si-O bonds. Si-O bonds strongly absorb hydrogen atoms and easily form highly hydrophilic hydroxyl groups (i.e. -OH), which have strong adsorption to water. Therefore, gas-phase SiO2 captures droplets and then flows into the pores in the ceramic-based composite material through the tubular channels in the mesh ablation groove, thereby obtaining a functional surface with super-hydrophilicity.

[0043] (3) The coating is prepared on the surface of the ceramic-based composite material after laser ablation by plasma spraying technology.

[0044] The contact angle of the ceramic-based composite material after laser ablation with different process parameters in Example 2 was measured: the ceramic-based composite material was placed on the horizontal lifting platform of the equipment, the platform was adjusted to gradually approach the stationary water droplet until it contacted the water droplet, and the changes in the droplet at the moment of contact were recorded.

[0045] Figure 7 The results of droplet adsorption test on the surface of the laser-ablated ceramic matrix composite under different scanning distance conditions. As can be seen from the figure, when the surface of the laser-ablated ceramic matrix composite comes into contact with water droplets, the droplets quickly adhere to the surface and disappear immediately. The time for the droplets to disappear increases as the scanning distance increases from 50μm to 110μm.

[0046] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A method for strengthening bonding of surface coating of ceramic matrix composite materials based on laser ablation of multi-scale physical and chemical microstructures, characterized in that: The following steps are involved: (1) Using laser to scan the surface of ceramic matrix composite material in a cross manner, a multi-scale physical microstructure is formed on the laser ablation surface; the multi-scale physical microstructure includes a mesh ablation groove, carbon fibers in the mesh ablation groove are sublimated to form tubular channels, convex plate arrays are formed between the mesh ablation grooves, and ablation products of agglomerates composed of nanoparticles are formed on the convex plate array; (2) The laser-ablated ceramic matrix composite material produces gas-phase SiO2 through chemical reaction, which captures the droplets and then flows into the pores in the ceramic matrix composite material through the tubular channels in the mesh ablation groove, thereby obtaining a functional surface with super-hydrophilicity. (3) Prepare coatings on the surface of ceramic-based composite materials after laser ablation.

2. The method for strengthening bonding of ceramic matrix composite surface coating based on laser ablation multi-scale physical and chemical microstructure according to claim 1 is characterized in that: In the step (1), the laser power is set at 4-10 W, the scanning distance is set at 50-110 μm, and the scanning speed is set at 500 mm / min.

3. The method for strengthening bonding of ceramic matrix composite surface coating based on laser ablation multi-scale physical and chemical microstructure according to claim 1 is characterized in that: In the step (1), the laser is a picosecond laser.

4. The method for strengthening bonding of ceramic matrix composite surface coating based on laser ablation multi-scale physical and chemical microstructure according to claim 1 is characterized in that: In the step (1), the width of the convex plate array is 20-50 μm, the particle size of the ablation product of the agglomerate is 1-10 μm, and the particle size of the nanoparticles is 200-400 nm.

5. The method for strengthening bonding of ceramic matrix composite surface coating based on laser ablation multi-scale physical and chemical microstructure according to claim 1 is characterized in that: In the step (2), the reason why the gas-phase SiO2 captures the droplets is that the Si-O bonds of the gas-phase SiO2 absorb hydrogen atoms to form highly hydrophilic hydroxyl groups, which adsorb water and dissolve in water.

6. The method for strengthening bonding of ceramic matrix composite surface coating based on laser ablation multi-scale physical and chemical microstructure according to claim 1 is characterized in that: In the step (3), a coating is prepared on the surface of the ceramic-based composite material after laser ablation by plasma spraying technology.

7. The method for strengthening bonding of ceramic matrix composite surface coating based on laser ablation multi-scale physical and chemical microstructure according to any one of claims 1 to 6, characterized in that: The ceramic-based composite material uses silicon carbide as a ceramic matrix and carbon fibers as reinforcing fibers.

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