A method for preparing ceramic matrix composite coatings based on laser-induced self-propagating high-temperature synthesis using powder-core wire.

Abstract

This invention discloses a method for preparing ceramic-based composite coatings using a laser-induced self-propagating high-temperature synthesis method based on powder-core wire. This method combines laser filament melting technology with a self-propagating high-temperature synthesis method, utilizing a high-energy laser beam to trigger the periodic self-propagating combustion reaction of the powder-core wire. Using powder-core wire instead of powder as the precursor material for coating preparation effectively reduces the dilution effect of the titanium alloy substrate on the coating microstructure. This method can synthesize ceramic-based composite coatings with a dense and uniform microstructure and microhardness values ​​close to the theoretical values, showing broad application prospects.

Description

Technical Field

[0001] This invention pertains to laser fused wire deposition technology, specifically relating to a process for preparing ceramic-based composite coatings using the principle of self-propagating combustion reaction and laser wire feeding deposition technology. Background Technology

[0002] Titanium and titanium alloys possess excellent comprehensive properties and are widely used in defense, aerospace, deep-sea operations, transportation, and medical devices. However, due to their relatively low hardness and poor wear resistance and oxidation resistance, surface failure often occurs during engineering service, which limits their application in harsh wear or high-temperature environments. Strengthening their surface wear resistance and oxidation resistance through certain methods is of great engineering significance for improving the applicability and reliability of titanium alloys.

[0003] Compared to overall optimization of titanium alloys, surface modification offers advantages such as low cost, short processing cycle, and high efficiency. It can maximize surface performance while ensuring sufficient overall properties (strength, toughness, and machinability) of the titanium alloy. Depositing high-performance coatings on titanium alloy surfaces can save time and R&D costs associated with material upgrades, overcome limitations in energy consumption and structural complexity of monolithic structures, and provide a basis for the use of titanium alloys in harsh working environments. Ceramic materials (such as TiB2, TiC, and TiB) are developed as hard protective coatings in surface engineering due to their extremely high hardness and excellent thermal stability. Furthermore, binary or multi-component ceramic matrix composites can integrate the properties of each component and exhibit superior fracture toughness compared to single-phase composites. Depending on the heat source used, coating preparation methods mainly include thermal spraying, arc welding, and laser melting deposition. Thermal spraying is limited by the deposition method, resulting in coatings with lower bonding strength and insufficient adhesion; while arc welding has a more dispersed heat source, leading to insufficient coating forming precision. Compared to the two methods mentioned above, laser melting deposition technology uses a high-energy laser beam as a heat source for deposition, which can produce a coating that is metallurgically bonded to the substrate and has a good shape.

[0004] However, the melting point of ceramic powder is much higher than that of the metal substrate. At commonly used laser powers of around 2000W, only a molten mixture of metal and ceramic phases can be formed. Only with laser powers greater than 5000W can continuous ceramic coatings be prepared, which places high demands on the operability of laser processing and the process control. Introducing a self-propagating high-temperature synthesis (SHS) reaction into the coating preparation process, utilizing the heat released from the self-sustaining chemical reaction between raw materials to complete the coating preparation, can effectively overcome the high-energy limitation of ceramic coating deposition, enabling the preparation of continuous ceramic coatings at low laser power. Furthermore, the in-situ self-generation of the melt structure under this method can eliminate the weak amorphous phase interfaces between ceramic particles in traditional powder sintering processes, obtaining clean, high-strength atomic bonding interfaces, thus achieving good microstructural stability and excellent mechanical properties.

[0005] Based on the form and feeding method of the raw materials used in coating preparation, laser deposition can be divided into three categories: powder pre-laying, synchronous powder feeding, and synchronous wire feeding. Powder pre-laying laser cladding does not involve process parameters related to powder or wire feeding, making the coating preparation process relatively simple. However, this method requires pre-laying powder onto the part surface, resulting in complex preliminary work, a long production cycle, and difficulty in adapting to the needs of industrial automation. Synchronous powder feeding laser deposition has a high degree of industrial automation and is currently widely used. However, it has inherent defects such as low powder utilization (30%), dust pollution, and high coating porosity, which does not conform to the concept of green and environmentally friendly industrial production, and its economic efficiency needs improvement. Furthermore, the loose powder flow in synchronous powder feeding makes it difficult to maintain the propagation and spread of combustion waves during the SHS process, making it difficult to form continuous ceramic coatings. Wire feeding laser deposition can provide a larger mass flow, and under the same conditions, its deposition efficiency and material utilization are higher than that of powder materials. Wires have greater applicability to deposition locations and environments, the process is simple to self-regulate, and it is easier to integrate into automated production. Meanwhile, filaments are typically manufactured through rolling and drawing processes, and their inherent material density can satisfy the steady-state propagation and self-propagation of combustion waves along the longitudinal direction of the filament in the SHS process. However, currently, additive manufacturing filaments are limited to solid filaments, and the flexibility of composition control for solid filaments is constrained by the processability of the filaments. High-strength and high-hardness ceramic materials are difficult to draw into filaments, which limits the feasibility of laser fused filament deposition for preparing ceramic coatings. Currently, the use of laser-induced SHS ceramic coatings mostly considers the raw material supply method of pre-laid powder. This method has a significant disadvantage: a large portion of the laser energy is absorbed by the metal substrate, and the dilution effect of the substrate can easily cause unevenness in the ceramic coating structure, leading to differences in coating performance in different areas. Currently, some scholars have proposed that powder-core filaments can combine the advantages of both powder and filaments (CN 110552004 B). The powder core inside the filament can be used to control the composition of the filament, and the self-propagating reaction can also be achieved by matching the metal outer skin with the internal powder core in a constant stoichiometric ratio. Additive manufacturing equipment based on powder-core filaments is simple and meets the needs of high-efficiency, low-cost, and automated industrial production. Summary of the Invention

[0006] This invention overcomes the shortcomings of existing technologies and provides a method for preparing ceramic-based composite coatings using self-propagating combustion reaction (SHS) and laser-fed deposition technology. A high-energy laser beam triggers the SHS reaction between a metal outer layer and an internal ceramic powder core. The continuous feeding of the wire enables the periodic combustion and propagation of the reaction flame. The wire melts and deposits onto the surface of the substrate, forming a metal-ceramic hybrid transition layer between the substrate surface and the coating. The coating prepared by this method has a dense and uniform structure, high bonding strength with the substrate, and a hardness close to the theoretical value, showing broad prospects for engineering applications.

[0007] The technical objective of this invention is achieved through the following technical solution.

[0008] A method for preparing ceramic-based composite coatings using self-propagating combustion reaction and laser wire-feeding deposition technology is carried out according to the following steps: Step 1, the base material is pure titanium or titanium alloy plate, and the powder core wire consists of an internal filler and an outer metal sheath. The internal filler is B4C powder or BN powder, and an SHS additive can also be added to the internal filler. The SHS additive is Al, B, or C, and the outer metal sheath is pure titanium. The SHS equation is 3Ti + 2BN = TiB2 + 2TiN or 3Ti + B4C = 2TiB2 + TiC. In the SHS reaction, excess titanium is added to compensate for the titanium evaporation loss during the SHS reaction process. The addition of SHS additives is to promote the complete SHS reaction. The core wire is made by rolling and drawing processes. The core wire has a certain material compactness and density, which is beneficial to the stable propagation of combustion waves during the SHS process. Step 2: Fix the base material on the three-dimensional worktable, adjust the laser spot diameter to between 2.5mm and 5mm, defocus, and irradiate the base material vertically with the laser beam. The core wire is fed into the irradiation area of ​​the laser beam by the wire feeder through the wire feed guide. Adjust the angle between the wire feed guide and the base material to 14°-22°, and adjust the angle between the side-blown protective gas copper tube and the base material to between 40°-65°. Step 3: According to the touch To determine the energy threshold required for the SHS reaction of the powder-core filament, select appropriate cladding process parameters within the process window: laser output power P = 900-3600W, laser scanning speed Vs = 0.8-9mm / s, side-blown protective gas flow rate = 12-22L / min, and powder-core filament feed speed Vw = 0.8-12mm / s. In step 4, after setting the position and process parameters, turn on the laser, and the powder-core filament is simultaneously fed out. The highly concentrated laser beam irradiates the powder-core filament, melting the outer metal sheath. The molten outer metal sheath then permeates the internal filler particles of the powder-core filament, thereby triggering the periodic combustion of the powder-core filament. The reaction occurs when a combustion wave forms at the end of the cored wire and propagates longitudinally into the solid region. When the combustion wave reaches a region where the temperature of the cored wire is lower than the SHS maintenance temperature, the combustion wave extinguishes, and the SHS product naturally transitions to the surface of the base material, spreading to form a molten pool. As the cored wire is continuously fed in, the SHS product continuously enters the molten pool. With the laser beam stationary, the smooth movement of the three-dimensional stage allows the cored wire to be continuously deposited onto the surface of the base material and solidified to form a continuous ceramic-based composite coating. At the same time, the heat transfer of the molten pool induces the formation of a metal-ceramic hybrid transition layer, ensuring a reliable connection between the ceramic coating and the base material.

[0009] In step 1, when the internal filler is BN, the molar ratio of the outer metal sheath, the internal filler and the SHS additive is (3-5):2:(0-0.4).

[0010] In step 1, when the internal filler is B4C, the molar ratio of the outer metal sheath, the internal filler, and the SHS additive is (3-4):1:(0-0.3).

[0011] In step 1, the diameter of the core wire is 1.2-2.4 mm, and the thickness of the outer metal sheath is 0.2-0.7 mm.

[0012] In step 2, the included angle α between the wire feeding guide and the base material is 15°-20°, the length of the powder core wire extending out of the wire feeding guide is 8-20mm, and the end of the powder core wire points to the front side of the laser beam spot.

[0013] In step 2, the diameter of the side-blown protective gas copper tube is 16mm, and the angle between the side-blown protective gas copper tube and the base material is in the range of 45°-60°.

[0014] In step 2, the distance between the bottom end of the side-blown protective gas copper tube and the base material is kept at 5-7mm, and the distance between the front end of the side-blown protective gas copper tube and the laser beam is fixed at 8-12mm.

[0015] In step 3, the laser output power P is 1000-3500W, the laser scanning speed Vs is 1-8mm / s, and the powder core wire feeding speed Vw is 1-10mm / s.

[0016] In step 3, the side-blown protective gas is an inert protective gas of Ar and He, and the flow rate of the side-blown protective gas is 15-20 L / min.

[0017] Compared with existing titanium alloy laser additive manufacturing and cladding processes, the innovation of this invention lies mainly in combining laser melting deposition technology with a self-propagating high-temperature synthesis method. This allows for the successful preparation of continuous ceramic coatings even with relatively low laser power. The method of preparing ceramic-based composite coatings using self-propagating combustion reaction and laser wire-feeding deposition technology has promising applications in additive manufacturing, surface engineering, and repair. Compared to fused powder, fused wire requires simpler auxiliary equipment, eliminating the need for complex powder feeding mechanisms, thus offering greater economic efficiency and industrial adaptability. Furthermore, in the laser-induced SHS process based on the powder-core wire, the SHS products are entirely provided by the powder-core wire as a precursor reactant, without the participation of the titanium alloy matrix, resulting in more controllable ceramic coating microstructure.

[0018] In the process of preparing ceramic coatings by triggering the self-propagating reaction of wire using electric arc heat, the SHS reaction proceeds periodically. However, since the electric arc is a non-focused heat source with a large heat source area and low heat source concentration, the initiation of the combustion wave requires a long incubation period. In existing technologies, the average incubation period and propagation reaction period corresponding to the electric arc-triggered SHS reaction are 0.26 s and 0.17 s, respectively. This means that after one cycle of SHS reaction products, there must be a 0.26 s interval before the next cycle of SHS reaction can begin, which is not conducive to the continuous formation of coatings. Compared with the electric arc heat source, the laser spot size is smaller, the energy density is highly concentrated, and it is at least an order of magnitude higher than that of the electric arc. This is beneficial for shortening the incubation period of the SHS reaction and is more conducive to the spreading of SHS reaction products on the base material. This is a major advantage of this invention over existing technologies—laser-induced SHS reactions based on powder-core wires, compared to arc-induced reactions, utilize a focused heat source, resulting in higher energy density and a shorter arc incubation period within one cycle. This improves the continuity of SHS reaction product deposition on the substrate surface, making it valuable for application in the ceramic matrix composite coating manufacturing industry. This laser-induced self-propagating high-temperature synthesis technology for ceramic composite coatings based on powder-core wires offers advantages such as good dual-phase stability, dense and uniform microstructure, high material utilization, high deposition efficiency, and energy saving and environmental friendliness. It provides a new approach for the continuous forming of ceramic coatings and is of great significance for surface modification and repair of titanium alloy parts, as well as the net-shape forming of ceramic composite materials in engineering applications. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the principle of the present invention, wherein 1 is a three-dimensional worktable, 2 is the base material, 3 is the wire feeder, 4 is the powder-core wire, 5 is the wire feeding guide tube, 6 is the laser auxiliary light source for high-speed imaging, 7 is the SHS combustion wave, 8 is the molten pool, 9 is the high-energy laser beam, 10 is the laser head, 11 is the side-blown protective gas copper tube, 12 is the continuous ceramic matrix composite coating, 13 is the high-speed camera, 14 is the working table travel direction, α is the angle between the wire feeding nozzle and the base material, and θ is the angle between the side-blown protective gas copper tube and the base material (continuous ceramic matrix composite coating).

[0020] Figure 2 This is a schematic diagram of the combustion wave propagation process in the high-temperature self-propagating high-temperature synthesis reaction of the present invention.

[0021] Figure 3 This is a cross-sectional schematic diagram of the powder core wire used in this invention, wherein 15 is the internal filler, 16 is the outer metal sheath, d is the diameter of the powder core wire, and s is the thickness of the outer metal sheath.

[0022] Figure 4 This is an image of the Ti-B4C type powder core wire used in the laser-induced self-propagating synthesis of ceramic composite coatings in Example 1.

[0023] Figure 5 This is a high-speed camera recording of the SHS process of the Ti-B4C powder core wire in Example 1 within one cycle, where the upper part is the combustion wave incubation period and the lower part is the combustion wave propagation period.

[0024] Figure 6 These are macroscopic morphology photographs of the TiB2–TiC ceramic matrix composite coating prepared in Example 1 (single-layer coating surface forming).

[0025] Figure 7 These are macroscopic morphology photographs of the TiB2–TiC ceramic matrix composite coating prepared in Example 1 (multi-layer (three-layer) coating surface formation).

[0026] Figure 8 These are macroscopic morphological photographs of the TC4 surface laser-clad 4Ti-3AlN coating in the prior art.

[0027] Figure 9 These are cross-sectional morphology photographs of the TiB2–TiC ceramic-based composite coating prepared in Example 1, with the left side being an OM photograph and the right side being a SEM photograph.

[0028] Figure 10 These are photographs of the microstructure of the TiB2-TiC coating prepared in Example 1.

[0029] Figure 11 It is the TiB2-TiC technology in the present technology x N y Photographs of the microstructure of the coating.

[0030] Figure 12 This is a hardness curve of the TiB2-TiC coating prepared in Example 1.

[0031] Figure 13 This is a comparison image of the indentation between the TiB2-TiC coating and the base material prepared in Example 1, where the left side is the coating and the right side is the base material.

[0032] Figure 14 The image shows the COF curves of the TiB2-TiC coating and the substrate prepared in Example 1, with the upper curve representing the substrate and the lower curve representing the coating.

[0033] Figure 15 These are macroscopic morphology photographs of the coating prepared in Example 2 (single-pass coating surface forming).

[0034] Figure 16 This is a cross-sectional morphology photograph of the coating prepared in Example 2.

[0035] Figure 17These are macroscopic morphology photographs of the coating prepared in Example 3 (single-pass coating surface forming).

[0036] Figure 18 These are cross-sectional morphology photographs of the coating prepared in Example 3, with the left side being an OM image and the right side being a SEM image.

[0037] Figure 19 These are photographs of the microstructure of the coating prepared in Example 3.

[0038] Figure 20 These are indentation morphology photographs of the coating prepared in Example 3.

[0039] Figure 21 These are macroscopic morphology photographs of the coating prepared in Example 4 (single-pass coating surface forming).

[0040] Figure 22 These are cross-sectional morphology photographs of the coating prepared in Example 4, with the left side being an OM image and the right side being a SEM image.

[0041] Figure 23 These are photographs of the microstructure of the coating prepared in Example 4. Detailed Implementation

[0042] The technical solution of the present invention will be further described below through specific embodiments.

[0043] The basic principle of a method for preparing laser-induced SHS ceramic composite coatings based on powder-core wire is as follows: Figure 1 As shown, the laser beam 9 is emitted from the laser head 10 and remains stationary during the coating preparation process. The base material 2 is placed on the three-dimensional worktable 1. The movement of the three-dimensional worktable 1 is controlled by a computer, which can realize the forward, backward, left, right, and up and down movement of the base material 2. The wire feeding method adopts a front-mounted type, that is, the powder core wire 4 always enters the molten pool 8 in front of the continuous ceramic matrix composite coating 12. In other words, under the premise that the laser beam 9 is stationary, the working table travel direction 14 needs to be adjusted to always stay away from the powder core wire 4, and the angle α between the wire feeding guide 5 and the base material 2 is kept between 15° and 20°. The end of the powder core wire 4 is moved to the front of the molten pool 8. The angle q between the side-blown protective gas copper pipe 11 and the base material 2 is adjusted between 45° and 60°. The bottom end of the side-blown protective gas copper pipe 11 is 5-7mm away from the base material 2, and the front end of the side-blown protective gas copper pipe 11 is 8-12mm away from the laser beam 9.

[0044] The diagram showing the end of the powder core wire 4 and the enlarged area of ​​the molten pool is shown below. Figure 2As shown, after the end of the powder core wire 4 is heated by laser irradiation energy, the SHS reaction is triggered, thereby generating a combustion wave 7. Accompanied by the wetting of the internal particles by liquid metal, the combustion wave spreads periodically to the solid wire area. When the combustion wave 7 spreads to the area not irradiated by the laser, the combustion wave is extinguished, and the self-propagating high-temperature synthesis product spreads to the surface of the parent material to form a molten pool 8.

[0045] Powder core wire 4 structure as Figure 3 As shown, the powder-core wire 4 consists of an inner filler 15 and an outer metal sheath 16. The outer metal sheath 16 is made of low-melting-point titanium strip that is easy to draw and form. The inner filler 15 consists of high-melting-point ceramic particles (such as B4C and BN) that can undergo an SHS reaction with titanium. The diameter d of the powder-core wire 4 is 1.2~2.4 mm. The thickness s of the titanium sheath is determined according to the chemical dosage ratio of the reaction system and the loose packing density of the powder, and the selection range is 0.2~0.7 mm.

[0046] Before opening the laser shutter, turn on the protective gas and set the Ar / He flow rate to 15~20 L / min to ensure that the wire, combustion wave, molten pool, and high-temperature area of ​​the coating are always in an Ar / He protective atmosphere during the cladding process. After preparation, open the laser shutter, and the laser beam 9 is emitted through the laser head 10. The wire feeder 3 feeds the wire synchronously, and the powder-core wire 4 is sent to the laser beam irradiation area through the wire feeding guide tube 5.

[0047] Laser beam 9 heats the powder core wire 4, triggering the SHS reaction between the molten outer metal sheath 16 and the internal filler 15. The molten outer metal sheath 16 capillarily spreads and wets the internal particles of the internal filler 15, causing the periodic generation and propagation of combustion waves. The SHS reaction products are deposited on the surface of the base material 2 and flow into the molten pool 8. At the same time, the reaction products carry a large amount of heat, causing part of the base material to melt. Therefore, a metal-ceramic mixing transition zone is generated between the coating and the base material. As the three-dimensional worktable 1 moves, the molten pool 8 cools and solidifies rapidly, completing the preparation of the continuous ceramic matrix composite coating 12. The high-speed camera laser auxiliary light source 6 provides an auxiliary light source for the high-speed camera 13, which records the preparation status and process of the continuous ceramic matrix composite coating 12 in real time.

[0048] Example 1—Powder Core Wire 4 uses self-made Ti-B4C type powder core wire, as shown in the picture. Figure 4 As shown, specifically, the outer metal sheath 16 is Cp-Ti (commercial pure titanium sheet), while the internal filler 15 uses pure B4C ceramic powder, wherein the molar ratio of Ti to B4C is 4:1.

[0049] A TiB2-TiC ceramic composite coating was prepared using a laser-induced self-propagating high-temperature synthesis reaction. The reaction principle is: 3Ti + B4C = 2TiB2 + TiC. The addition of excess Ti is to offset the burn-off and vaporization losses of Ti during the self-propagating high-temperature reaction process. The powder core wire 4 has a diameter of 2.4 mm and an outer metal sheath 16 with a thickness of 0.4 mm. The powder core wire 4 is produced by strip bending, tube groove filling, rolling, and drawing processes.

[0050] The base material is made of titanium alloy (model Ti-6Al-4V), with dimensions of 100*100*8mm. The laser source used is an Nd:YAG solid-state laser (GSI, JK2003SM), with an output laser wavelength of 1064nm. Positive defocusing is used, with a focal length of 300mm and a laser spot size of Φ4mm. The wire feeding angle α is adjusted to 15°, and the angle q between the side-blown protective gas copper tube and the base material is maintained at 45°. Ar is selected for the side-blown protective gas, and the gas flow rate is adjusted to 20L / min. The laser power is set to 1100W, the wire feeding speed is 4mm / s, the table travel speed is 2mm / s, and the multi-pass welding overlap rate is set to 50%. In addition, the length of the powder-cored wire 4 extending out of the wire feeding guide is adjusted to 10mm. Subsequently, a laser melting deposition test is conducted.

[0051] As attached Figure 5 As shown, the SHS reaction proceeds periodically. The combustion wave diffuses from the end of the wire to the edge of the laser spot and then extinguishes. As the wire is continuously fed in, the laser triggers the SHS reaction of the powder-core wire again. Therefore, one cycle of the SHS reaction can be divided into the incubation period of the combustion wave and the combustion propagation period. Under the process conditions provided in this example, the average incubation period and combustion propagation period corresponding to the laser-induced SHS reaction are 0.052s and 0.040s, respectively. The incubation period of the SHS reaction is only 1 / 5 of that of the prior art. It can be seen that the laser-induced SHS reaction based on powder-core wire has a shorter incubation period than that of arc-induced SHS reaction, which improves the continuity of the deposition process of SHS reaction products on the substrate surface and has certain promotional value in the preparation industry of SHS ceramic matrix composite coatings. Due to the repeated formation and extinguishing of the combustion wave in the SHS process, the SHS reaction products enter the molten pool at a certain frequency, and some periodic ripples will be found on the surface of the formed coating. However, its surface quality has been greatly improved compared with the ceramic coatings prepared by traditional laser cladding methods, as shown in the attached figure. Figure 6 As shown in the attached image. In the multi-coat system, the layers bond well together without noticeable cracks, as indicated. Figure 6 As shown in the figure. Due to the high melting point of the ceramic phase, directly cladding ceramic powder onto the titanium alloy surface can easily lead to incomplete melting of the powder, resulting in numerous defects on the coating surface. The prepared coating is shown in the attached figure. Figure 8As shown. Increasing the content of metal powder in the coating raw material can effectively solve this problem, but the resulting coating is no longer a pure ceramic coating (existing technical literature Liu Hongxi, et al., Microstructure and high-temperature oxidation resistance of in-situ synthesized TiN / Ti3Alintermetallic composite coatings on Ti6Al4V alloy by laser cladding process[J]).

[0052] From the appendix Figure 9 It can be seen that the titanium alloy base material has a relatively small dilution effect on the coating microstructure. A transition region exists between the pure ceramic coating and the base material, which can alleviate the accumulation of thermal stress between the ceramic components of the coating and the base material, thus promoting reliable bonding between the ceramic coating and the base material. The pure ceramic component coating can be formed using self-propagating combustion reaction and laser fused wire deposition technology, which differs from traditional methods. The microstructures of the ceramic coating prepared by the method of this invention and the coatings formed on the surface of titanium alloys with similar components using traditional methods are shown in the attached figures. Figure 10 With appendix Figure 11 As shown in the figure, the coating substrate prepared by the method of the present invention is TiB2 with embedded TiC components. The distribution and content of TiB2 within the SHS ceramic layer are shown. TiB2 is tightly embedded in the TiC matrix, resulting in a dense, uniform structure with low porosity. In contrast, existing technical literature (Dai Jingjie, et al., Microstructure and wear properties of self-lubricating TiB2-TiCxNy ceramic coatings on Ti-6Al-4Valloy fabricated by laser surface alloying [J]) uses pure ceramic powder as the coating raw material. In coatings prepared by traditional laser cladding, the substrate is not a ceramic component, but rather molten titanium as the substrate, forming a ceramic phase-reinforced metal matrix composite coating characterized by ceramic phase embedding within a metal matrix. Therefore, it can be concluded that the method provided by the present invention has greater advantages than traditional methods for preparing pure ceramic matrix composite coatings.

[0053] The hardness of the coating was evaluated using an MHV2000 microhardness tester according to GB / T4340.1-2009 standard, with a load of 500 g and a loading time of 15 s. Microhardness values ​​were measured every 0.4 mm along the direction of maximum penetration from the cladding layer surface to the base material, and the calculated average hardness was 2179 HV. 0.5Based on the conversion relationship of 1 GPa = 102.04 HV, the average equivalent strength of the coating is 21.35 GPa, which is close to the hardness of dense ceramic blocks prepared by traditional methods (21.5-26.7 GPa), indicating broad application prospects. One indentation of the ceramic coating is selected and compared with the TC4 indentation. This invention utilizes the comparison between the indentations of a ceramic-based composite coating prepared based on self-propagating combustion reaction and laser filament melting method and the base material, such as... Figure 13 As shown.

[0054] The room temperature tribological properties of the coating and the base material were tested using a UMT Tribolab ball-disc planar linear reciprocating tribological testing machine. A 9.525 mm GCr15 ball was selected as the grinding pair. During the tribological performance test, the load was 10 N, the frequency was 10 Hz, the half-cycle stroke length was 5 mm, and the wear time was 10 min. The coefficient of friction (COF) between the ceramic matrix composite coating prepared based on self-propagating combustion reaction and laser filament melting method and the base material was compared using a test load of 10 N. Figure 14 As shown, the dense and uniform microstructure of the coating enables this ceramic composite coating to exhibit excellent stability during wear, resulting in a low and stable coefficient of friction. Compared to the base material, the coating exhibits more stable frictional properties and a lower coefficient of friction.

[0055] Example 2 - The core wire 4 uses a self-made Ti-BN type core wire, specifically the outer metal sheath 16 is Cp-Ti, while the internal filler 15 is pure BN ceramic powder, and the molar ratio of Ti to BN is 2:1.

[0056] A TiB2-TiC ceramic composite coating was prepared using a laser-induced self-propagating high-temperature synthesis reaction. The reaction principle is: 3Ti + 2BN = TiB2 + 2TiN. The addition of excess Ti is to offset the burn-off and vaporization losses of Ti during the self-propagating high-temperature reaction process. The powder core wire 4 has a diameter of 1.6 mm and an outer metal sheath 16 with a thickness of 0.2 mm. The powder core wire 4 is produced by strip bending, tube groove filling, rolling, and drawing processes.

[0057] The base material is made of titanium alloy (model Ti-6Al-4V), with dimensions of 100*100*8mm. The laser source used is an Nd:YAG solid-state laser (GSI, JK2003SM), with an output laser wavelength of 1064nm. Positive defocusing is used, with a focal length of 300mm and a laser spot size of Φ4mm. The wire feeding angle α is adjusted to 15°, and the angle q between the side-blown protective gas copper tube and the base material is maintained at 45°. Ar is selected for the side-blown protective gas, and the gas flow rate is adjusted to 20L / min. The laser power is set to 1800W, the wire feeding speed is 6mm / s, the table travel speed is 2mm / s, and the multi-pass welding overlap rate is set to 33%. In addition, the length of the powder-cored wire 4 extending out of the wire feeding guide is adjusted to 10mm.

[0058] Laser melting deposition experiments were then conducted, resulting in a continuous TiB2-TiN composite coating. Because the Ti-BN system has a higher ignition temperature, lower heat release, and poorer thermal conductivity than the Ti-B4C system, preparing ceramic composite materials using this system is more difficult. Therefore, as shown in the attached figure... Figure 15 and 16 As shown, the formed ceramic coating lacks density and contains unmelted defects. Although this system can produce continuous ceramic-based composite coatings, no further experiments were conducted due to the presence of some defects in the coating.

[0059] Example 3 - The core wire 4 uses a self-made Ti-B4C type core wire, specifically the outer metal sheath 16 is Cp-Ti, while the internal filler 15 uses pure B4C ceramic powder and pure Al powder, with a molar ratio of Ti, B4C and Al of 3:1:0.2.

[0060] A TiB2-TiC ceramic composite coating was prepared using a laser-induced self-propagating high-temperature synthesis reaction. The reaction principle is: 3Ti + B4C = 2TiB2 + TiC. Al has a low melting point, and the liquid phase it generates at high temperatures can promote atomic diffusion, thus accelerating the synthesis of TiB2 and TiC. The powder-core wire 4 has a diameter of 2.0 mm and an outer metal sheath 16 with a thickness of 0.3 mm. The powder-core wire 4 is produced through strip bending, tube groove filling, rolling, and drawing processes.

[0061] The base material is made of titanium alloy (model Ti-6Al-4V), with dimensions of 100*100*8mm. The laser source used is an Nd:YAG solid-state laser (GSI, JK2003SM), with an output laser wavelength of 1064nm. Positive defocusing is used, with a focal length of 300mm and a laser spot size of Φ4mm. The wire feeding angle α is adjusted to 15°, and the angle q between the side-blown protective gas copper tube and the base material is maintained at 45°. Ar is selected for the side-blown protective gas, and the gas flow rate is adjusted to 20L / min. The laser power is set to 1200W, the wire feeding speed is 4mm / s, the table travel speed is 2mm / s, and the multi-pass welding overlap rate is set to 50%. In addition, the length of the powder-cored wire 4 extending out of the wire feeding guide is adjusted to 10mm.

[0062] Subsequently, laser melting deposition experiments were conducted to obtain a continuous TiB2-TiC ceramic-based composite coating.

[0063] As attached Figure 17 As shown in Figure 20, the overall morphology of the coating is similar to that of Example 1. Due to the increase in laser power, the TiB2 phase in the coating grows to a certain extent, and the grain size of the coating is larger than that in Example 1. The hardness of the coating was evaluated using an MHV2000 microhardness tester according to GB / T4340.1-2009 standard, with a load of 500 g and a loading time of 15 s. Microhardness values ​​were measured every 0.4 mm along the direction of maximum penetration from the cladding layer surface to the base material, and the calculated average hardness was 1882 HV. 0.5 Based on the conversion relationship of 1 GPa = 102.04 HV, the average equivalent strength of the coating is 18.44 GPa.

[0064] Example 4 - The core wire 4 uses a self-made Ti-B4C type core wire, specifically the outer metal sheath 16 is Cp-Ti, while the internal filler 15 uses pure B4C ceramic powder and graphite C powder, with a molar ratio of Ti, B4C and C of 4:1:0.3.

[0065] A TiB2-TiC ceramic composite coating was prepared using a laser-induced self-propagating high-temperature synthesis reaction. The reaction principle is: 3Ti + B4C = 2TiB2 + TiC. Graphite C was added to promote TiC synthesis. The core wire 4 has a diameter of 2.0 mm, and the outer metal sheath 16 has a thickness of 0.3 mm. The core wire 4 is produced through strip bending, tube groove filling, rolling, and drawing processes.

[0066] The base material is made of titanium alloy (model Ti-6Al-4V), with dimensions of 100*100*8mm. The laser source used is an Nd:YAG solid-state laser (GSI, JK2003SM), with an output laser wavelength of 1064nm. Positive defocusing is used, with a focal length of 300mm and a laser spot size of Φ4mm. The wire feeding angle α is adjusted to 20°, and the angle q between the side-blown protective gas copper tube and the base material is maintained at 45°. Ar is selected for the side-blown protective gas, and the gas flow rate is adjusted to 20L / min. The laser power is set to 1000W, the wire feeding speed is 3mm / s, the table travel speed is 2mm / s, and the multi-pass welding overlap rate is set to 50%. In addition, the length of the powder-cored wire 4 extending out of the wire feeding guide is adjusted to 10mm.

[0067] Subsequently, laser melting deposition experiments were conducted to obtain a continuous TiB2-TiC ceramic-based composite coating.

[0068] As attached Figure 21 As shown in Figure 23, the overall morphology of the coating is similar to that of Example 1. The prepared coating matrix is ​​TiB2 with embedded TiC components. The coating structure is similar to that of Example 1. The amount of C added is small, so the structure of the coating is not changed.

[0069] Adjusting the process parameters according to the present invention can achieve the preparation of ceramic-based composite coatings, and testing has shown that they exhibit performance essentially consistent with the present invention. The present invention has been described above as exemplary. It should be noted that any simple modifications, alterations, or other equivalent substitutions that can be made by those skilled in the art without creative effort, without departing from the core of the present invention, fall within the protection scope of the present invention.

Claims

1. A method for preparing ceramic-based composite coatings using a laser-induced self-propagating high-temperature synthesis method based on powder-core wire, characterized in that, A high-energy laser beam triggers the SHS reaction between the metal outer skin and the internal ceramic powder core. During the continuous feeding of the powder core wire, the reaction flame is periodically burned and spread. The powder core wire melts and deposits onto the surface of the base material, forming a metal-ceramic hybrid transition layer between the base material surface and the coating. The process is carried out according to the following steps: Step 1: Fix the base material on the three-dimensional worktable, adjust the diameter of the laser spot to be between 2.5mm and 5mm, defocus, and irradiate the base material vertically with the laser beam. The powder core wire is fed into the irradiation area of ​​the laser beam by the wire feeder through the wire feeding guide. Adjust the angle between the wire feeding guide and the base material to 14°-22°, and adjust the angle between the side blow protective gas copper tube and the base material to be between 40°-65°. Step 2: Based on the energy threshold required to trigger the SHS reaction of the powder core wire, select appropriate cladding process parameters within the process window: laser output power P is 900-3600W, laser scanning speed Vs is 0.8-9mm / s, side-blown protective gas flow rate is 12-22L / min, and powder core wire feeding speed Vw is 0.8-12mm / s. Step 3: Turn on the laser and simultaneously feed out the powder-core filament. The highly concentrated laser beam irradiates the powder-core filament, melting the outer metal sheath. The molten outer metal sheath infiltrates the internal filler particles of the powder-core filament, thereby triggering a periodic combustion reaction of the powder-core filament. A combustion wave is formed at the end of the powder-core filament and propagates longitudinally into the solid region. When the combustion wave propagates to a region where the temperature of the powder-core filament is lower than the SHS maintenance temperature, the combustion wave is extinguished, and the SHS products naturally transition to the surface of the base material, spreading on the surface of the base material to form a molten pool. As the powder-core filament is continuously fed in, the SHS products continuously enter the molten pool. With the laser beam stationary, the smooth movement of the three-dimensional worktable allows the powder-core filament to be continuously deposited onto the surface of the base material and solidified to form a continuous ceramic-based composite coating. At the same time, the heat transfer of the molten pool induces the formation of a metal-ceramic hybrid transition layer, ensuring a reliable connection between the ceramic coating and the base material. The base material is made of pure titanium or titanium alloy plate. The powder core wire is composed of internal filler and outer metal sheath. The internal filler is made of B4C powder and SHS additive is added to the internal filler. The SHS additive is made of Al, B or C. The outer metal sheath is made of pure titanium. The molar ratio of the outer metal sheath, internal filler and SHS additive is (3-4):1:(0-0.3).

2. The method for preparing ceramic matrix composite coatings using a laser-induced self-propagating high-temperature synthesis method based on powder-core wire as described in claim 1, characterized in that, The diameter of the core wire is 1.2-2.4mm, and the thickness of the outer metal sheath is 0.2-0.7mm.

3. The method for preparing ceramic matrix composite coatings using a laser-induced self-propagating high-temperature synthesis method based on powder-core wire as described in claim 1, characterized in that, In step 1, the included angle α between the wire feeding guide and the base material is 15°-20°, the length of the powder core wire extending out of the wire feeding guide is 8-20mm, and the end of the powder core wire points to the front side of the laser beam spot.

4. The method for preparing ceramic matrix composite coatings using a laser-induced self-propagating high-temperature synthesis method based on powder-core wire according to claim 1, characterized in that, In step 1, the diameter of the side-blown protective gas copper tube is 16mm, and the angle between the side-blown protective gas copper tube and the base material is in the range of 45°-60°.

5. The method for preparing ceramic matrix composite coatings using a laser-induced self-propagating high-temperature synthesis method based on powder-core wire according to claim 1, characterized in that, In step 1, the distance between the bottom end of the side-blown protective gas copper tube and the base material is kept at 5-7mm, and the distance between the front end of the side-blown protective gas copper tube and the laser beam is fixed at 8-12mm.

6. The method for preparing ceramic matrix composite coatings using a laser-induced self-propagating high-temperature synthesis method based on powder-core wire according to claim 1, characterized in that, In step 2, the laser output power P is 1000-3500W, the laser scanning speed Vs is 1-8mm / s, and the powder core wire feeding speed Vw is 1-10mm / s.

7. The method for preparing ceramic matrix composite coatings using a laser-induced self-propagating high-temperature synthesis method based on powder-core wire according to claim 1, characterized in that, In step 2, the side-blown protective gas is an inert protective gas of Ar or He, and the flow rate of the side-blown protective gas is 15-20 L / min.

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