Method for preparing enhanced latticed titanium-based composite material through laser cladding

Abstract

The invention belongs to the technical field of titanium-based composite materials, and particularly relates to a method for preparing an enhanced latticed titanium-based composite material through laser cladding, mixed strengthening phase powder is prepared, then lattice structure processing is conducted on the surface of a titanium alloy matrix, in the lattice structure, the width of warps and wefts is 0.3 mm-0. 8mm, the depth is 0.5 mm-2 mm, and the distance between the warps and the wefts is 0.5 mm-2 mm; then the mixed strengthening phase powder is subjected to laser cladding into grids on the surface of the titanium alloy matrix, and finally stress relief annealing and polishing are conducted to obtain the latticed titanium-based composite material. According to the method, synergistic preparation of structure prefabrication and strengthening phase filling is achieved, the problem that in a traditional method, a grid structure and a strengthening phase cladding layer are not tightly combined is solved, the strengthening phase of the prepared titanium-based composite material is evenly distributed, firm metallurgical bonding is formed between the strengthening phase and a grid wall, and compared with a traditional coating structure, the bending strength of the composite material is improved, and the impact toughness of the composite material is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of titanium-based composite materials, and particularly relates to a method for preparing a reinforced grid-shaped titanium-based composite material by laser cladding. BACKGROUND

[0002] Titanium-based composite materials are widely used in key fields due to their high strength, low density, excellent corrosion resistance and biocompatibility. Traditional methods for preparing titanium-based composite materials, such as powder metallurgy, casting and hot-pressing sintering, have problems such as difficulty in forming complex structures, easy production of defects and high energy consumption. Although laser cladding technology can be used to form titanium-based composite materials, existing technologies mainly focus on single coating or block-shaped composite materials, which cannot meet the collaborative requirements of "lightweight - high strength". However, there are two major problems in existing technologies: first, the machining precision of the grid structure on the surface of titanium alloy is low, and traditional mechanical machining is prone to edge burrs and structural deformation, which cannot guarantee the consistency of the grid size; second, the mixed strengthening phase powder has poor cladding effect in the grid structure, and problems such as insufficient bonding between the cladding layer and the grid wall and uneven distribution of the strengthening phase easily occur, resulting in a decline in the overall performance of the composite material. Therefore, developing a preparation method that first precisely processes the grid structure on the surface of titanium alloy and then efficiently cladding the mixed strengthening phase powder has become a technical problem to be solved in the field. SUMMARY

[0003] To achieve the above-mentioned application purposes, the application provides the following technical solutions: The application provides a method for preparing a reinforced grid-shaped titanium-based composite material by laser cladding, comprising the following steps: S1, mixed strengthening phase powder preparation; mixing the strengthening phase powder and the titanium-based powder at a mass ratio of (5-15):(85-95), ball milling and drying to obtain the mixed strengthening phase powder for standby; S2, titanium alloy substrate surface grid structure processing; first, pretreating the titanium alloy substrate, and then processing the grid structure on the surface of the titanium alloy substrate, wherein the width of the warp and weft in the grid structure is 0.3-0.8 mm, the depth is 0.5-2 mm, and the spacing is 0.5-2 mm; S3, laser cladding; under the protection of an inert gas atmosphere, the mixed strengthening phase powder is laser cladded into the grid on the surface of the titanium alloy substrate; S4, stress relief annealing of the composite material after laser cladding, and polishing to obtain the grid-shaped titanium-based composite material.

[0004] Preferably, in step S1, the strengthening phase powder is TiC powder, one or more of the powders are mixed; and the titanium-based powder is pure titanium powder or titanium alloy powder with a purity of ≥99.5%.

[0005] Preferably, in step S1, the reinforcing phase powder has a particle size of 10-50 μm, and the titanium-based powder has a particle size of 50-150 μm.

[0006] Preferably, in step S1, the two powders are added to a planetary ball mill in anhydrous ethanol as a medium, the ball-to-material ratio is 10-15:1, the rotation speed is 200-300 r / min, and the ball milling is performed for 4-6 h; after the ball milling, vacuum drying is performed at 60-80 ℃ for 2-3 h.

[0007] Preferably, in step S2, after the surface of the titanium alloy substrate is polished with sandpaper to remove the oxide scale and scratches, ultrasonic cleaning is performed for 15-20 min, and then vacuum drying is performed at 50-70 ℃ for 1-2 h.

[0008] Preferably, in step S2, a laser engraving machine or a numerical control milling machine is used to process a grid structure on the surface of the pretreated titanium alloy substrate, the debris in the grid slots is then blown away, and then anhydrous ethanol is used to wipe the surface to remove impurities in the grid slots.

[0009] Preferably, in step S3, the parameters of the laser cladding are as follows: the laser power is 800-1200 W, the scanning speed is 300-500 mm / min, the powder feeding amount is 15-25 g / min, the defocusing amount is 10-15 mm, the inert gas is argon, and the gas flow is 15-20 L / min.

[0010] Preferably, in step S4, in the stress relief annealing process, the composite material is placed in a vacuum annealing furnace, the vacuum annealing furnace is heated to 600-800 ℃ at a rate of 5-10 ℃ / min under argon protection, and the temperature is maintained for 2-4 h, and the furnace is cooled to room temperature.

[0011] Preferably, in step S4, in the polishing process, the surface of the composite material is polished with 80#, 240#, 600#, 1000# and 1500# sandpaper in sequence, and then burrs and protrusions are removed.

[0012] Compared with the prior art, the present application has the following beneficial technical effects: The present application realizes the synergistic preparation of "structure prefabrication + reinforcing phase filling" by precisely processing a grid structure on the surface of a titanium alloy substrate and then cladding mixed reinforcing phase powder in the grid slots, thereby solving the problem of poor combination of the grid structure and the reinforcing phase cladding layer in the traditional method.

[0013] The application processes the grid structure by using a laser engraving machine or a numerical control milling machine first, has high precision (grid size error is less than or equal to 0.05 mm), avoids the defects of mechanical processing, ensures that the grid groove wall is smooth, and then accurately cladding the mixed strengthening phase powder in the grid groove, so that the strengthening phase is uniformly distributed and forms a firm metallurgical combination with the grid wall. Compared with the traditional coating structure, the bending strength of the composite material is improved, and the impact toughness is improved.

[0014] The whole preparation process of the application does not need complex molds, the grid structure parameters and the strengthening phase ratio can be flexibly adjusted, the titanium-based composite material surface cladding layer prepared has repairability, adapts to different application scene requirements, has low energy consumption and high efficiency, and is suitable for large-scale production. DETAILED DESCRIPTION

[0015] In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative labor also belong to the scope of protection of the present disclosure.

[0016] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this subject matter belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0017] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. Those skilled in the art will appreciate that embodiments described herein can be combined with one another.

[0018] A method for preparing an enhanced grid-shaped titanium-based composite material by laser cladding, comprising the following steps: S1, mixed strengthening phase powder preparation; the strengthening phase powder is mixed with the titanium-based powder at a mass ratio of preferably (5-15):(85-95), ball milled and dried to obtain the mixed strengthening phase powder for standby; Specifically, in step S1, the titanium-based powder is selected from pure titanium powder or titanium alloy powder with a purity of greater than or equal to 99.5%, and the powder particle size is 50-150 microns; the strengthening phase powder is selected from TiC powder, The two powders are added to a planetary ball mill in a mass ratio, the powder particle size is 10-50 μm; the ball-to-powder ratio is preferably (10-15): 1, for example, it can be 10:1, 11:1, 12:1, 13:1, 14:1, 15:1; the rotation speed is preferably 200-300 r / min, for example, it can be 200 r / min, 220 r / min, 250 r / min, 270 r / min, 300 r / min; the ball milling is preferably 4-6 h, for example, it can be 4 h, 5 h, 6 h; after ball milling, vacuum drying at 60-80°C, for example, it can be 60°C, 70°C, 80°C, for 2-3 h, to obtain a uniformly mixed mixed strengthening phase powder.

[0019] S2, processing of the titanium alloy substrate surface grid structure; first, pretreating the titanium alloy substrate, then processing the grid structure on the surface of the titanium alloy substrate, in the grid structure, the warp and weft width is preferably 0.3-0.8 mm, for example, it can be 0.3 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm; the depth is preferably 0.5-2 mm, for example, it can be 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm; the pitch is preferably 0.5-2 mm, for example, it can be 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm; Specifically, in step S2, during the pretreatment of the titanium alloy substrate, first, polish the surface of the titanium alloy substrate with 400#, 800#, and 1200# sandpaper in sequence to remove the oxide scale and scratches, then ultrasonic clean with acetone solution (ultrasonic power 300-500 W) for 15-20 min, and finally vacuum dry at 50-70°C for 1-2 h; Specifically, in step S2, a laser engraving machine (wavelength 1064 nm, output power 50-100 W) or a numerical control milling machine is used to process the grid structure on the surface of the pretreated titanium alloy substrate, after processing, the grid slot is blown clean with compressed air, and then the surface is wiped with anhydrous ethanol to ensure that there is no impurity in the grid slot.

[0020] S3, laser cladding; under the protection of an inert gas atmosphere, the mixed strengthening phase powder is laser cladded into the grid on the surface of the titanium alloy substrate; Specifically, in step S3, an optical fiber laser (wavelength 1060 nm-1080 nm, maximum output power 3000 W) is used, and is equipped with an automatic powder feeding system and a numerical control motion platform for laser cladding. During the process, the titanium alloy substrate with the grid structure is fixed on the numerical control motion platform, the laser head is adjusted, and the laser beam is focused in the grid groove; start the equipment, the automatic powder feeding system delivers the mixed strengthening phase powder to the laser action area in the grid groove, the laser beam makes the powder melt quickly, and at the same time the numerical control motion platform moves according to the grid path to ensure that the mixed strengthening phase powder fills the grid groove and forms metallurgical bonding with the grid wall; during the cladding process, the laser power is preferably 800 W-1200 W, for example, it can be 800 W, 900 W, 1000 W, 1100 W, 1200 W, the scanning speed is preferably 300 mm / min-500 mm / min, for example, it can be 300 mm / min, 350 mm / min, 400 mm / min, 450 mm / min, 500 mm / min, the powder feeding amount is preferably 15 g / min-25 g / min, for example, it can be 15 g / min, 18 g / min, 20 g / min, 22 g / min, 25 g / min, the defocusing amount is preferably 10 mm-15 mm, for example, it can be 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, the inert gas argon continuously covers the cladding area, and the gas flow is preferably 15 L / min-20 L / min, for example, it can be 15 L / min, 16 L / min, 17 L / min, 18 L / min, 19 L / min, 20 L / min.

[0021] S4, stress relief annealing of the laser cladded composite material, and polishing to obtain a grid-shaped titanium-based composite material; Specifically, in step S4, during the stress relief annealing process, the cladded composite material is placed in a vacuum annealing furnace, under argon protection, the vacuum annealing furnace is preferably heated at a rate of 5°C / min-10°C / min, for example, it can be 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, the temperature is preferably raised to 600°C-800°C, for example, it can be 600°C, 650°C, 700°C, 750°C, 800°C, the holding time is preferably 2h-4h, for example, it can be 2h, 3h, 4h, and the furnace is cooled to room temperature to eliminate internal stress; during the polishing process, the surface of the composite material is polished with 80#, 240#, 600#, 1000#, and 1500# sandpaper in sequence, so that the grid cladding layer is flush with the surface of the substrate, and burrs and protrusions are removed.

[0022] Specifically, the grid-shaped titanium-based composite material of laser cladding, the cladding layer may be abraded in long-term work, and the laser cladding of step S3 can be performed again for repair when the cladding layer is abraded; based on the construction of the grid structure of step S2, point-to-point cladding layer repair can be realized.

[0023] The technical solutions in the application will be clearly and completely described below with reference to the embodiments in the application: Embodiment 1 In this embodiment, a reinforced grid-shaped titanium-based composite material is prepared by using a TC4 titanium alloy plate as a substrate, and the following steps are included. Step 1: mixed strengthening phase powder preparation; the titanium-based powder is TC4 titanium alloy powder with a purity of 99.6% and a particle size of 50-100 μm, and the composition (mass percentage) is Al 6.0%, V 4.0%, and Ti 90.0%; the strengthening phase powder is TiC powder with a particle size of 10-30 μm; the TiC:TC4 ratio is 8:92 by mass, and the planetary ball mill is added with a ball-to-material ratio of 12:1 and a rotation speed of 250 r / min for 5 h; vacuum drying is performed at 70°C for 2.5 h to obtain the mixed strengthening phase powder.

[0024] Step 2: titanium alloy substrate surface grid structure processing; the substrate is a TC4 plate with a size of 100 mm×100 mm×5 mm; Pre-treatment: polishing with 400#, 800#, and 1200# sandpaper in sequence, 500W power acetone ultrasonic cleaning for 18 min, and 60°C vacuum drying for 1.5 h; Grid processing: using a laser engraving machine (power 80W), the grid parameters are as follows: width 0.5 mm, depth 1 mm, and spacing 1 mm; after processing, compressed air is blown and anhydrous ethanol is wiped.

[0025] Step 3: laser cladding parameter setting and grid cladding; using a fiber laser (wavelength 1064 nm, power 3000 W), an automatic powder feeding system, and a numerical control motion platform; fixing the substrate, focusing the laser beam in the grid groove, and cladding according to the grid path to ensure that the powder fills the grid groove; Cladding parameters: laser power 1000 W, scanning speed 400 mm / min, powder feeding amount 20 g / min, defocusing amount 12 mm, and Ar gas flow rate 18 L / min.

[0026] Step 4: stress relief annealing first: placing the cladded composite material into a vacuum annealing furnace, heating to 700°C at a rate of 8°C / min under argon protection, keeping for 3 h, and cooling with the furnace; then polishing with 80#, 240#, 600#, 1000#, and 1500# sandpaper in sequence until the surface is flat, to obtain the grid-shaped titanium-based composite material.

[0027] Performance testing: The flexural strength of the mesh-like titanium matrix composite material is 1050 MPa (approximately 850 MPa for pure TC4 matrix), the impact toughness is 60 J / cm² (approximately 45 J / cm² for pure TC4 matrix), the bonding strength between the mesh cladding layer and the matrix is ​​≥80 MPa, and there is no peeling phenomenon.

[0028] Example 2 This embodiment uses pure titanium sheet as the matrix to prepare a reinforced mesh-like titanium-based composite material, including the following steps: Step 1: Preparation of mixed reinforcing phase powder; the titanium-based powder is pure titanium powder with a purity of 99.8% and a particle size of 80μm-150μm; the reinforcing phase powder is... Mixed with SiC powder (mass ratio 1:1), particle size 30μm-50μm; according to mass ratio ( The mixture of pure titanium and pure titanium in a ratio of 12:88 was added to a planetary ball mill at a ball-to-material ratio of 15:1 and a rotation speed of 300 r / min for 6 hours. The mixture was then vacuum dried at 80℃ for 3 hours to obtain the mixed reinforced phase powder.

[0029] Step 2: Processing the mesh structure on the surface of the titanium alloy substrate; the substrate is made of pure titanium sheet, with dimensions of 150mm×150mm×6mm; Pretreatment: Sand with 400#, 800# and 1200# sandpaper in sequence, ultrasonically clean with acetone at 400W power for 20 minutes, and vacuum dry at 70℃ for 2 hours; Mesh processing: CNC milling machine is used to process the mesh with the following parameters: width 0.8mm, depth 1.5mm, and spacing 1.5mm. After processing, the mesh is blown with compressed air and wiped with anhydrous ethanol.

[0030] Step 3: Laser cladding parameter setting and cladding within the grid; using a fiber laser (wavelength 1064nm, power 3000W), automatic powder feeding system, and CNC motion platform; fixing the substrate, focusing the laser beam within the grid groove, and cladding according to the grid path to ensure that the powder fills the grid groove; Cladding parameters: laser power 1200W, scanning speed 350mm / min, powder feed 25g / min, defocusing amount 15mm, Ar gas flow rate 20L / min.

[0031] Step 4: Stress-relief annealing: Place the clad composite material into a vacuum annealing furnace, heat it to 750℃ at 10℃ / min under argon protection, hold it at that temperature for 4 hours, and then cool it with the furnace; then polish it with 80#, 240#, 600#, 1000#, and 1500# sandpaper in sequence until the surface is flat to obtain a grid-like titanium-based composite material.

[0032] Performance test: the grid-shaped titanium-based composite material has a bending strength of 1100 MPa (about 650 MPa for pure titanium substrate), an impact toughness of 58 J / cm2 (about 38 J / cm2 for pure titanium substrate), a grid cladding layer and substrate bonding strength of ≥75 MPa, and good structural integrity.

[0033] Comparative Example 1 In step 2 of the comparative example, no grid structure processing is performed, and only a flat titanium alloy substrate surface is retained. The remaining steps are the same as in Example 1.

[0034] The titanium-based composite material prepared in the comparative example has a bending strength of 950 MPa, an impact toughness of 52 J / cm2, and a coating and substrate bonding strength of about 65 MPa, which is lower than the bonding strength of Example 1. There are small pores on the coating surface, and due to the absence of grid structure constraints, the strengthening phase has a slight aggregation phenomenon at the edge of the coating. The lightweight effect is significantly weaker than that of Example 1.

[0035] Comparative Example 2 The comparative example uses a traditional powder metallurgy method to prepare a titanium-based composite material. Step 1: preparation of mixed strengthening phase powder; titanium-based powder selected TC4 titanium alloy powder, purity 99.6%, particle size 50μm-100μm, composition (mass percentage): Al 6.0%, V 4.0%, Ti 90.0%; strengthening phase powder selected TiC powder, particle size 10μm-30μm; mixed according to mass ratio TiC:TC4 = 8:92, added to a planetary ball mill, ball-to-material ratio 12:1, rotation speed 250r / min, ball milling 5h; vacuum drying at 70℃ for 2.5h to obtain mixed strengthening phase powder.

[0036] Step 2: load the mixed strengthening phase powder into a graphite mold and pre-press form on a press machine at a pressure of 20MPa to obtain a 100mm×100mm×5mm block-shaped billet. Place the billet into a sintering furnace, heat to 1200℃ at a rate of 5℃ / min under Ar gas protection, and keep the temperature for 4h. Cool the furnace to room temperature.

[0037] Step 3: polish the surface to be flat using 80#, 240#, 600#, 1000#, and 1500# sandpaper in sequence.

[0038] The composite material prepared in the comparative example has a bending strength of 900MPa and an impact toughness of 48J / cm2. There are a small amount of pores and un-melted defects in the material, and the grid-shaped lightweight structure cannot be prepared.

[0039] The grid size error, bending strength, impact toughness, bonding strength, structural defects, and lightweight effect of Examples 1-2 and Comparative Examples 1-3 are shown in Table 1: Table 1 Test Results

[0040] As can be seen from Table 1, the bending strength, impact toughness and bonding strength of Comparative Example 1-2 are all decreased compared with Example 1. The titanium-based composite prepared in Comparative Example 1-2 has more defects, so that the structural performance and light weight of the composite are decreased compared with Example 1.

[0041] The above only describes the preferred embodiments of the present application, and it should be noted that, for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method of laser cladding to produce a reinforced, grid-like titanium matrix composite material, characterized in that, The method comprises the following steps: S1, mixing the strengthening phase powder preparation; the strengthening phase powder is mixed with the titanium-based powder according to the mass ratio (5-15):(85-95), ball milling and drying to obtain the mixed strengthening phase powder for standby; S2, processing the grid structure on the surface of the titanium alloy base; the titanium alloy base is pretreated, and then the grid structure is processed on the surface of the titanium alloy base; in the grid structure, the warp and weft width is 0.3-0.8 mm, the depth is 0.5-2 mm, and the interval is 0.5-2 mm; S3, laser cladding; the mixed strengthening phase powder is laser cladded into the grid on the surface of the titanium alloy base under the protection of inert gas atmosphere; S4, stress relief annealing of the composite material after laser cladding, and polishing to obtain the grid-shaped titanium-based composite material.

2. The method of claim 1, wherein the laser cladding is performed by a laser beam having a power of 1 to 5 kW, a scanning speed of 1 to 5 m / min, and a laser beam diameter of 0.5 to 2 mm. In step S1, the reinforcing phase powder is a TiC powder, powder, one or more of SiC powder is mixed; the titanium-based powder is a pure titanium powder with a purity of ≥ 99.5% or a titanium alloy powder.

3. The method of claim 1, wherein the laser cladding is performed by a laser beam having a power of 1 to 5 kW, a scanning speed of 0.5 to 2 m / min, and a laser beam diameter of 0.5 to 2 mm. In step S1, the particle size of the strengthening phase powder is 10-50 μm, and the particle size of the titanium-based powder is 50-150 μm.

4. The method of claim 1, wherein the laser cladding is performed by a laser beam having a power of 1 to 5 kW, a scanning speed of 0.5 to 2 m / min, and a laser beam diameter of 0.5 to 2 mm. In step S1, during the ball milling process, the two powders are added to a planetary ball mill, anhydrous ethanol is used as the medium, the ball-to-material ratio is (10-15):1, the rotation speed is 200-300 r / min, and the ball milling time is 4-6 h; after ball milling, vacuum drying is performed at 60-80 °C for 2-3 h.

5. The method of claim 1, wherein, In step S2, during the pretreatment of the titanium alloy base, the surface of the base is polished with sandpaper, the oxide skin and scratches are removed, ultrasonic cleaning is performed for 15-20 min, and then vacuum drying is performed at 50-70 °C for 1-2 h.

6. The method of claim 1, wherein, In step S2, a laser engraving machine or a numerical control milling machine is used to process the grid structure on the surface of the pretreated titanium alloy base, the debris in the grid groove is blown away, anhydrous ethanol is used to wipe the surface, and the impurities in the grid groove are removed.

7. The method of claim 1, wherein the laser cladding is performed by a laser beam having a power of 1 to 5 kW, a scanning speed of 0.5 to 2 m / min, and a laser beam diameter of 0.5 to 2 mm. In step S3, the parameters of the laser cladding are as follows: the laser power is 800-1200 W, the scanning speed is 300-500 mm / min, the powder feeding amount is 15-25 g / min, the defocusing amount is 10-15 mm, the inert gas is argon, and the gas flow is 15-20 L / min.

8. The method of claim 1, wherein the laser cladding is performed by a laser beam having a power of 1 to 5 kW, a scanning speed of 0.5 to 2 m / min, and a laser beam diameter of 0.5 to 2 mm. In step S4, during the stress relief annealing process, the composite material is placed in a vacuum annealing furnace, the vacuum annealing furnace is heated to 600-800 °C at a rate of 5-10 °C / min under the protection of argon, and then the temperature is maintained for 2-4 h, and the furnace is cooled to room temperature.

9. The method of claim 1, wherein the laser cladding is performed by a laser beam having a power of 1 to 5 kW, a scanning speed of 0.5 to 2 m / min, and a laser beam diameter of 0.5 to 2 mm. In step S4, during the polishing process, the surface of the composite material is polished with 80#, 240#, 600#, 1000#, and 1500# sandpaper in sequence, and then burrs and protrusions are removed.

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