In-situ reaction multi-element ceramic phase reinforced titanium-based composite coating and preparation method thereof

Abstract

The invention relates to the field of metal material surface strengthening, in particular to an in-situ reaction multi-element ceramic phase reinforced titanium-based composite coating and a preparation method thereof. The preparation method comprises the steps that titanium alloy powder and B4C powder are mixed, and mixed powder is obtained; the mixed powder is conveyed to a cladding focus under atmosphere protection, reaction gas is introduced, laser cladding is conducted, and the in-situ reaction multi-element ceramic phase reinforced titanium-based composite coating is formed on the surface of the metal sample; the reaction gas is nitrogen; the laser power is 1-2 kW, the scanning speed is 5-20 mm / s, and the multi-pass cladding lap joint rate is 40%-80%. By regulating and controlling the laser cladding process, optimizing the laser power, the scanning speed and the reaction gas flow and utilizing a dispersion strengthening mechanism and a solid solution strengthening mechanism of a ceramic phase generated through in-situ reaction, the hardness and the wear resistance of the composite coating are improved, the problems that a traditional titanium-based coating is low in hardness and poor in wear resistance are effectively solved, and the service life of the coating is prolonged. The method is suitable for surface strengthening of key components in the fields of aerospace, ocean engineering and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of surface strengthening of metal materials, and mainly relates to an in-situ reaction multi-element ceramic phase reinforced titanium-based composite coating and a preparation method thereof. BACKGROUND

[0002] Metal matrix composite coating has a wide application in the fields of aerospace, energy equipment, automobile industry and the like due to its excellent mechanical properties, wear resistance, corrosion resistance and high-temperature stability. Traditional metal matrix ceramic composite coating improves hardness and wear resistance by adding ceramic phases (TiC, SiC, Al2O3, etc.), but due to inherent characteristics of the material and limitations of the preparation process, there are several key technical bottlenecks: ① the difference in bonding between the ceramic phase (covalent / ion bond) and the metal matrix (metal bond) leads to poor interface wettability, forming a weakly bonded mechanical interface, which is prone to peeling; ② nano ceramic particles are prone to agglomeration due to high surface energy, which can be improved by surface modification, but it is difficult to achieve single particle dispersion in industrialization; ③ the difference in thermal expansion coefficient between ceramic and metal induces thermal stress, which induces radial thermal fatigue cracks at high temperature. These problems coupled together lead to an insufficient 2-fold increase in hardness, a 20%-30% fluctuation in wear resistance, and a thermal shock life of less than 500 times. Current research focuses on in-situ synthesis and gradient interface design to break through the interface and dispersion bottlenecks and promote the development of high-performance ceramic phase reinforced metal matrix composite coating.

[0003] The in-situ reaction generation method has significant advantages. The clean interface formed by the reaction significantly outperforms the traditional externally added ceramic particle method in terms of bonding strength, and can achieve uniform dispersion of nano / micron ceramic phases, effectively avoiding particle agglomeration problems, without the need for pretreatment of the ceramic phase, which can simplify the process and reduce production costs. The proportion of the reaction system can also be flexibly adjusted to precisely control the performance of the coating hardness, toughness and the like. The preparation method of the in-situ reaction ceramic phase reinforced metal matrix composite coating mainly includes laser cladding, thermal spraying, vacuum sintering, magnetron sputtering and other methods. The ceramic phases generated by the reaction mainly include carbides, nitrides, oxides and borides. Laser cladding technology can achieve in-situ transient generation of various ceramic phases due to its ultra-high energy density (10 6 -10 7 W / cm 2 ), which can achieve sub-stable phase retention or nano-crystalline ceramic phase generation in the ultra-fast cooling process, and can precisely control the heat input to achieve micro-region reaction control through micro-scale adjustable light spots. When multiple layers are cladded, a gradient composite coating with controllable content can be constructed. At the same time, laser cladding is suitable for various substrates such as iron, nickel, titanium and aluminum, and can prepare high-melting-point difference systems (such as Al substrate + TiB2, melting point difference > 1500℃), and the obtained coating forms a metallurgical bond with the substrate, with a density of > 99.5%. Laser cladding technology has unique advantages in the in-situ reaction generation of ceramic phase reinforced metal matrix composite coating.

[0004] Titanium alloys are widely used in aerospace, marine engineering and biomedical fields due to their high specific strength, excellent corrosion resistance and good biocompatibility. However, the low surface hardness (about 200 HV) and poor wear resistance of titanium alloys seriously limit their long-term service performance under harsh working conditions. Laser cladding technology has become an effective means of surface strengthening of titanium alloys due to its high energy density, rapid solidification and metallurgical bonding. In-situ reaction synthesis technology has outstanding technical advantages compared to traditional external ceramic particle method. This method directly generates ceramic phases in the substrate through chemical reaction, forming a clean and high-strength interface, which fundamentally solves the common problem of poor interface bonding in the external particle method. During the reaction, micron-scale ceramic phases are spontaneously formed, and the uniformity is significantly improved, effectively overcoming the agglomeration phenomenon that cannot be avoided in the external particle method. By introducing ceramic reinforcing phases (such as TiC, TiN, TiB2) into the titanium matrix through in-situ reaction, the performance of the coating can be significantly improved. However, existing technologies focus on the generation of single ceramic phase, and the research on multi-phase synergistic reinforcement mechanism is insufficient, and the process parameter optimization is not systematic, resulting in limited improvement of coating performance. SUMMARY

[0005] In view of the deficiencies of the prior art described above, the purpose of the present application is to provide an in-situ reaction multi-element ceramic phase reinforced titanium-based composite coating and a preparation method thereof. By optimizing the laser cladding process and generating TiN, TiC, TiB2 and AlN multi-element ceramic reinforcing phases in-situ, solid solution strengthening is formed in the substrate, which greatly improves the hardness and wear resistance of the composite coating, effectively solving the problems of low hardness and poor wear resistance of traditional titanium-based coatings.

[0006] The technical solution of the present application is as follows:

[0007] A preparation method of an in-situ reaction multi-element ceramic phase reinforced titanium-based composite coating, comprising the following steps:

[0008] Titanium alloy powder and B4C powder are mixed to obtain a mixed powder;

[0009] The mixed powder is transported to the cladding focal point under the protection of an atmosphere and a reaction gas is introduced, laser cladding is performed, and the in-situ reaction multi-element ceramic phase reinforced titanium-based composite coating is formed on the surface of the metal sample; the reaction gas is nitrogen; the parameters of the laser cladding are: laser power 1-2 kW, scanning speed 5-20 mm / s, and multi-pass cladding overlap rate 40%-80%.

[0010] In the laser cladding, the laser power is limited to 1-2 kW, the scanning speed is 5-20 mm / s (low speed for high thickness cladding, high speed for thin layer precision machining), and the multi-pass cladding overlap rate is 40%-80% (to ensure defect-free interlayer metallurgical bonding). The sample surface is accurately positioned at the powder accumulation cladding focal point (positioning accuracy ±0.1 mm), and the uniform distribution of the reinforcing phase is realized by the time-space matching of synchronous powder feeding (rotating speed 0.5-3.0 r / min) and laser beam.

[0011] The application provides in-situ reaction multi-ceramic phase reinforced titanium-based composite coating by dissolving B4C with specific high laser power to provide B source, C source and Ti element for full contact reaction.

[0012] Furthermore, the application dissolves the introduced B4C by high-energy laser, and promotes the in-situ reaction of ceramic phases in the molten pool flow under the condition of introducing N2 reaction gas. The method has the advantages of obtaining multiple ceramic phases, uniform distribution, dispersion strengthening effect on the substrate, and part of B, C and N elements solid solution and solid solution strengthening effect in the substrate.

[0013] That is, the cladding layer formed by the application has a reinforcing mechanism including dispersion strengthening of uniformly distributed ceramic phases and solid solution strengthening of C, N and B elements in the substrate.

[0014] Further, the reaction gas is introduced at a gas pressure of 0.1-0.5 mbar.

[0015] Further, the mixed powder is conveyed to the cladding focal point by argon protection under the condition of powder feeding rotating speed 0.5-3.0 r / min.

[0016] The high-precision conveying and reaction control of the mixed powder are realized by triple synergistic control: ① argon main protection flow (purity ≥ 99.99%) to prevent titanium alloy high-temperature oxidation; ② nitrogen partial pressure reaction (0.1-0.5 mbar) to promote in-situ generation of TiN hard phase; and ③ dynamic matching of powder feeding rotating speed and laser power (1-2 kW) to ensure uniform distribution of TiN composite reinforcing phase in the molten pool. This method can improve the hardness of the cladding layer and control the porosity to ≤0.5%.

[0017] Further, the mass fraction of B4C powder in the mixed powder is 1%-5%, and the titanium alloy powder makes up the balance.

[0018] Further, the titanium alloy powder and the B4C powder are mechanically mixed and dried to obtain the mixed powder.

[0019] Preferably, the mechanical mixing process can adopt mechanical dry mixing method and ball milling mixing method.

[0020] Preferably, the drying treatment can be at 60-100℃ to remove moisture, so that the moisture content is <0.1%.

[0021] Further, the titanium alloy powder includes one or more of TA, TB, TC4 mixed, with a purity of ≥99%, and a particle size range of 15-150μm.

[0022] The B4C powder has a purity of ≥99%, and a powder particle size range of 1-50μm.

[0023] Further, after polishing or / and sandblasting and cleaning of the surface of the metal sample, the laser cladding is performed on the surface thereof to obtain the in-situ reaction multi-ceramic phase reinforced titanium-based composite coating.

[0024] The preparation method of the application utilizes the advantages of high energy density, rapid solidification and metallurgical bonding of laser cladding, generates multi-ceramic reinforced phases in-situ, solves the technical problems faced by traditional metal-based ceramic composite coatings by adding ceramic phases, improves the interface wettability, uniformly disperses the ceramic phases, and suppresses the radial thermal fatigue cracks caused by stress mismatch. The titanium-based composite coating is prepared by using laser cladding technology, B4C powder is mixed, nitrogen gas is introduced as a reaction gas, carbon, boron and nitrogen elements are introduced into the coating, multi-ceramic reinforced phases such as TiN, TiC, TiB2 and AlN are generated in-situ, and non-metallic elements such as N, C and B are distributed in the matrix to form solid solution strengthening.

[0025] By adjusting the laser cladding process, optimizing the laser power, scanning speed and reaction gas flow, the hardness and wear resistance of the composite coating are greatly improved, effectively solving the problems of low hardness and poor wear resistance of traditional titanium-based coatings, and the method is suitable for surface strengthening of key components in the fields of aerospace, marine engineering and the like.

[0026] The application also provides an in-situ reaction multi-ceramic phase reinforced titanium-based composite coating.

[0027] Further, the in-situ reaction multi-ceramic phase reinforced titanium-based composite coating includes α-Ti matrix phase, β-Ti matrix phase and multi-ceramic reinforced phase.

[0028] Preferably, the multi-ceramic reinforced phase includes TiN, TiC, TiB2 and AlN, etc.

[0029] Preferably, N, C and B elements are distributed in the Ti matrix to form solid solution strengthening.

[0030] Further, the thickness of the in-situ reaction multi-ceramic phase reinforced titanium-based composite coating is 300-1500μm.

[0031] The application utilizes the advantages of high energy density, rapid solidification and metallurgical bonding of laser cladding, generates multi-element ceramic reinforcing phases in-situ by adding a small amount of reaction phases and passing reaction gas, and solves the problems of poor interface wettability, easy agglomeration of ceramic phases and many thermal stress cracks in traditional metal-based ceramic composite coatings by adding ceramic phases.

[0032] Compared with the prior art, the application has the following beneficial effects:

[0033] 1. The multi-element ceramic in-situ reaction proposed in the application innovatively uses titanium alloy powder (such as TA, TB, TC4 series) mixed with B4C powder as raw material, and combines with the technology of precisely controlled nitrogen partial pressure (0.1-0.5 mbar) to synchronously initiate 2Ti+N2→2TiN, 2Al+N2→2AlN and 5Ti+B4C→2TiB2+TiC double in-situ reactions in the laser cladding high-temperature molten pool. This process generates TiN, TiB2, TiC and AlN and other high-hardness ceramic reinforcing phases in-situ at one time, and makes them uniformly distributed in the α-Ti+β-Ti matrix. At the same time, N, C, B and other non-metallic elements are solid-solution distributed in the matrix to form solid solution strengthening, and the synergistic strengthening effect of multi-element ceramic phases is realized through careful design of material components and reaction path.

[0034] 2. The application proposes a composite gas precision synergistic control and high-precision process integration method, which realizes triple precision synergistic control through the innovative argon-nitrogen composite gas system, high-purity argon (≥99.99%) prevents titanium oxidation, specific low-pressure nitrogen (0.1-0.5 mbar) promotes TiN in-situ reaction, and argon as powder carrier ensures stable delivery. At the same time, combined with ultra-high precision process control, such as high-resolution powder feeder (0.1 r / min, fluctuation ≤±2%) to ensure accurate powder flow, sample positioning accuracy (±0.1 mm) to ensure accurate intersection of powder flow and laser beam, and dynamic optimization matching of key parameters such as laser power (1-2 kW), scanning speed (5-20 mm / s), powder feeding speed (0.5-3.0 r / min), and overlap rate (40%-80%). The integration of the whole high-power (≥2 kW) laser cladding system (including coaxial powder feeding head, precision mechanical arm, cooling system) ensures the high efficiency, stability and automation of the complex process.

[0035] 3、The in-situ reaction multi-ceramic phase reinforced titanium-based composite coating of the application has controllable structure. The above innovative material and process successfully realize microstructure optimization and significant performance improvement. The generated multi-ceramic reinforced phase (TiN, TiB2, TiC and AlN) greatly improves the hardness and wear resistance of the coating by using solid solution strengthening. By gas protection and parameter precision control, the porosity of the coating is controlled at a very low level (≤0.5%), the optimized overlap rate (40%-80%) ensures excellent metallurgical bonding between the coating and the substrate and between the layers, and the coating thickness can be accurately controlled within a large range (300-1500 μm) to meet different application requirements. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The morphology and phase XRD results of the TC4 titanium alloy powder, B4C powder and composite powder used in Example 1 of the application.

[0037] a figure - TC4 titanium alloy powder morphology; b figure - B4C powder morphology; c figure - composite powder morphology; d figure - phase XRD result.

[0038] In d figure, the one on the top is the phase XRD result of B4C powder, and the one on the bottom is the phase XRD result of TC4 powder.

[0039] Figure 2 The composition of the laser cladding system and the schematic diagram of the laser cladding process in Example 1 of the application.

[0040] Figure 3 The metallographic morphology and carbon, nitrogen element energy spectrum area scan results of the composite coating prepared in Example 1 of the application after corrosion. N and C non-metallic elements are solid-solution distributed in the substrate to form solid solution strengthening.

[0041] Figure 4 The transmission electron microscope ceramic phase morphology and multi-element energy spectrum area scan results of the composite coating prepared in Example 1 of the application, which verify that N, C, B and other non-metallic elements are solid-solution distributed in the substrate to realize solid solution strengthening.

[0042] The first row from left to right is HAADF, C, B; the second row from left to right is Ti, Al, N.

[0043] Figure 5 The hardness comparison chart of the composite coating (TC4-B4C-N2) and the substrate prepared in Example 1 of the application.

[0044] Figure 6 The wear resistance comparison chart of the composite coating (TC4-B4C-N2) and the substrate (TC4) prepared in Example 1 of the application. DETAILED DESCRIPTION

[0045] The application provides an in-situ reaction multi-ceramic phase reinforced titanium-based composite coating and a preparation method thereof. To make the purpose, technical scheme and effects of the application more clear and explicit, the application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the application and not to limit the application.

[0046] The application provides a preparation method of an in-situ reaction multi-ceramic phase reinforced titanium-based composite coating, comprising the following steps:

[0047] Step 1: polishing or / and sandblasting and cleaning the surface of the metal sample.

[0048] The specific process is as follows:

[0049] The surface roughness reaches Ra 12.5 μm. Specifically, 80-120 mesh sandpaper is used for rough grinding to remove the oxide layer and avoid subsequent cross scratches; or / and 80-120 mesh white corundum is vertically sandblasted at a gas pressure of 0.4-0.6 MPa for 30-60 seconds.

[0050] The oil is removed by acetone ultrasonic cleaning for 5-10 minutes, and then the sample is rinsed with deionized water and dried.

[0051] Step 2: titanium alloy powder (including TA, TB or TC4 series, purity ≥ 99%, particle size 15-150 μm) is mixed with B4C powder (purity ≥ 99%, particle size 1-50 μm) at a specific ratio, and after mechanical mixing, the mixed powder is dried to obtain the mixed powder.

[0052] The mass fraction of B4C powder in the mixed powder is 1%-5%, and the titanium alloy powder makes up the balance.

[0053] The mechanical mixing process can adopt mechanical dry mixing method (three-dimensional mixer, 30-60 minutes) or ball milling mixing method (inert gas protection, 2-10 hours).

[0054] The drying treatment needs to be dried at 60-100°C for 2 hours to remove water (moisture content <0.1%).

[0055] The mixed powder is suitable for laser cladding and can significantly improve the hardness and wear resistance of the cladding layer.

[0056] Step 3: the laser cladding track is planned according to the surface profile of the metal sample, then the powder is delivered by argon gas, nitrogen gas is introduced at the same time for in-situ reaction, high-precision powder delivery and reaction control are realized, and the in-situ reaction multi-ceramic phase reinforced titanium-based composite coating is prepared on the surface of the metal sample by accurately controlling the laser cladding process parameters.

[0057] 1. The specific parameters of high-precision delivery and reaction control of mixed powder are as follows: the mixed powder (titanium alloy + B4C) is delivered to the cladding focus area by argon carrier under the precise control of the powder feeder rotation speed of 0.5-3.0 r / min, and 0.1-0.5 mbar of nitrogen is introduced as a reaction gas.

[0058] The process is realized through triple synergistic control: ① argon main protection flow (purity ≥ 99.99%) to prevent titanium alloy high-temperature oxidation; ② nitrogen partial pressure reaction (0.1-0.5 mbar) to promote in-situ generation

[0059] of TiN hard phase; ③ dynamic matching of powder delivery speed and laser power (1-2 kW) to ensure uniform distribution of TiN composite reinforcement phase in the molten pool. This method can improve the hardness of the cladding layer while controlling the porosity to ≤0.5%.

[0060] 2. The specific process parameters of laser cladding are as follows: laser power 1-2 kW, scanning speed 5-20 mm / s (low speed for high-thickness cladding, high speed for thin-layer precision machining), multi-pass cladding overlap rate 40%-80% (to ensure defect-free interlayer metallurgical bonding). The sample surface is precisely positioned at the cladding focus point of powder accumulation (positioning accuracy ±0.1 mm), and the uniform distribution of the reinforcement phase is realized through the time and space matching of synchronous powder delivery (rotation speed 0.5-3.0 r / min) and laser beam.

[0061] Moreover, the laser cladding process of the present application is carried out by a commercially available laser cladding system.

[0062] Specifically, the laser cladding system is characterized by a high-power laser (power ≥ 2 kW), a high-precision mechanical arm (load ≥ 10 kg), a precision powder feeder (minimum controllable powder delivery speed 0.1 r / min), a coaxial powder delivery and cladding head, and a cooling system. The system controls the movement of the cladding head according to the pre-set trajectory by programming the mechanical arm, realizing automatic cladding of complex three-dimensional structures. The coaxial powder delivery and cladding head can ensure the precise synchronization of the powder flow and the laser beam, the high resolution (0.1 r / min) of the powder feeder ensures the stability of the powder delivery amount control (fluctuation ≤±2%), and the combination of the high-power laser (2-6 kW) can meet the cladding needs of titanium alloy, B4C and other composite powders. The cooling system maintains the temperature stability of the optical elements through water cooling / gas cooling, ensuring the process consistency of long-time continuous operation.

[0063] The application generates a reinforced coating with a multiphase composite structure by in-situ reaction of laser cladding. In the cladding process, in-situ reaction occurs in the molten pool: Ti+N2→TiN; 5Ti+B4C→2TiB2+TiC. The phase composition of the composite coating includes α-Ti and β-Ti dual-phase matrix and uniformly distributed multi-ceramic reinforced phase (TiN, TiC, TiB2 and AlN, etc.). The thickness of the composite coating can be accurately controlled in the range of 300-1500 μm.

[0064] The application is further described below through specific examples.

[0065] Example 1

[0066] TC4 titanium alloy plates are selected as the metal sample substrate. The oxidation layer is removed by coarse grinding with 120 mesh sandpaper to achieve a surface roughness of Ra12.5 μm. The oil is removed by ultrasonic cleaning with acetone for 5-10 minutes, and then the sample is rinsed with deionized water and dried.

[0067] Titanium alloy powder TC4 (purity ≥99%, particle size 15-53 μm) and B4C powder (purity ≥99%, particle size 6-10 μm) are mixed in a mass ratio of 99:1. After mixing, the powder is dried at 80°C for 2 hours to remove moisture.

[0068] Figure 1 The morphology and phase XRD results of the TC4 titanium alloy powder and B4C powder and the composite powder selected in Example 1 are shown.

[0069] The laser cladding track is planned according to the surface profile of the metal sample, then argon is used to deliver the powder, nitrogen is introduced for in-situ reaction, high-precision delivery and reaction control of the mixed powder are achieved, and by accurately controlling the laser cladding process parameters, a titanium-based composite coating reinforced by in-situ reaction of multi-ceramic phase is prepared on the surface of the metal sample.

[0070] During the laser cladding process, the laser power is set to 1500 W, the scanning speed is 15 mm / s, the powder feeding rate is 1.6 r / min, the overlap rate is 40%, and the multi-pass cladding uses a reciprocating track with a single pass length of 30 mm. Figure 2 The laser cladding system used in Example 1 and the schematic diagram of the laser cladding process are shown.

[0071] Argon is used to achieve high-precision delivery of the mixed powder, and nitrogen is used to control the reaction. The argon output pressure is 0.5 mbar, and the nitrogen output pressure is 0.5 mbar.

[0072] Figure 3The microstructure of the in-situ reaction ceramic phase reinforced metal matrix composite coating prepared under the process conditions of Example 1 is shown. The reaction generated ceramic phase structure shows good corrosion resistance, and the carbon and nitrogen element distribution shown by the energy spectrum clarifies the structure of the ceramic phase.

[0073] Figure 4 The transmission electron microscope ceramic phase morphology and multi-element energy spectrum area scanning results of the composite coating prepared in Example 1 are shown. Titanium element reacts with carbon, nitrogen and boron to form ceramic reinforcing phase. Under the action of laser energy field, gas-liquid and solid-liquid double reactions occur in the molten pool. TiN dendrites are generated by the reaction of molten Ti and active nitrogen, and TiB2 whiskers and TiC particles are generated by the reaction of [B] and [C] produced by the decomposition of B4C and Ti.

[0074] At the same time, non-metallic elements such as N, C and B are distributed in the matrix in solid solution, which solid solution strengthens the performance of the substrate.

[0075] As shown in Figure 5 and Figure 6 , the hardness and wear resistance of the in-situ reaction ceramic phase reinforced metal matrix composite coating are significantly improved, with a hardness increase of 2.6 times and a wear resistance increase of 13.6 times.

[0076] Example 2:

[0077] TC4 titanium alloy plates were selected as metal sample substrates. White corundum of 80-120 mesh was vertically sandblasted at a gas pressure of 0.4-0.6 MPa for 30-60 seconds to make the surface roughness reach Ra12.5 μm. The surface was cleaned by ultrasonic acetone for 5-10 minutes to remove grease, and then deionized water was used for washing and drying.

[0078] Titanium alloy powder TC4 (purity ≥99%, particle size 15-53 μm) and B4C powder (purity ≥99%, particle size 6-10 μm) were mixed in a mass ratio of 95:5 to increase the content of B4C powder in the mixed powder and increase the proportion of in-situ reaction generated ceramic phase. After mixing, the powder was dried at 80°C for 2 hours to remove moisture.

[0079] During the laser cladding process, the laser power was set to 2000 W. Increasing the laser power helps the decomposition of B4C to generate [B] and [C], and promotes the in-situ reaction process of generating ceramic phase. The scanning speed was 15 mm / s, the powder feeding rate was 1.6 r / min, the overlap rate was 40%, and the multi-pass cladding used a reciprocating trajectory with a single pass length of 30 mm.

[0080] An argon-nitrogen composite gas system was used to achieve high-precision delivery and reaction control of the mixed powder. The argon output gas pressure was 0.5 mbar, and the nitrogen output gas pressure was 0.5 mbar.

[0081] The reaction process in the molten pool during the laser cladding process of Example 2 is similar to that of Example 1. Under the action of the laser energy field, gas-liquid and solid-liquid double reactions occur in the molten pool. The molten Ti reacts with active nitrogen to form TiN dendrites. The [B] and [C] produced by the decomposition of B4C react with Ti to form TiB2 whiskers and TiC particles. A multi-element synergistic reinforcement structure is formed inside the coating. At the same time, the solid solution strengthening mechanism is used to significantly improve the hardness and wear resistance of the coating.

[0082] Example 3:

[0083] A 30CrMnSiA flat plate was selected as the metal sample substrate. The oxide layer was removed by coarse grinding with 120 grit sandpaper to achieve a surface roughness of Ra 12.5 μm. The oil was removed by ultrasonic cleaning with acetone for 5-10 minutes. The sample was then rinsed with deionized water and dried.

[0084] Titanium alloy powder TC4 (purity ≥ 99%, particle size 15-53 μm) and B4C powder (purity ≥ 99%, particle size 6-10 μm) were mixed in a mass ratio of 99:1 to increase the content of B4C powder in the mixed powder and increase the proportion of in-situ reaction generated ceramic phase. The mixed powder was dried at 80°C for 2 hours to remove moisture.

[0085] During the laser cladding process, the laser power was set to 1500 W. Increasing the laser power helps to decompose B4C to produce [B] and [C], and promotes the in-situ reaction to generate ceramic phase. The scanning speed was 15 mm / s, the powder feeding rate was 1.6 r / min, the overlap rate was 40%, and the multi-pass cladding used a reciprocating trajectory with a single pass length of 30 mm.

[0086] A argon-nitrogen composite gas system was used to achieve high-precision powder delivery and reaction control. The argon output pressure was 0.5 mbar and the nitrogen output pressure was 0.5 mbar.

[0087] The reaction process in the molten pool during the laser cladding process of Example 3 is similar to that of Example 1. After cladding, the in-situ reaction ceramic phase reinforced titanium-based composite coating forms a metallurgical bond with the iron-based metal substrate. Under the action of the laser energy field, gas-liquid and solid-liquid double reactions occur in the molten pool. The molten Ti reacts with active nitrogen to form TiN dendrites. The [B] and [C] produced by the decomposition of B4C react with Ti to form TiB2 whiskers and TiC particles. A multi-element synergistic reinforcement structure is formed inside the coating. At the same time, the solid solution strengthening mechanism is used to significantly improve the hardness and wear resistance of the coating.

[0088] Example 4:

[0089] TC4 sleeve part was selected as sample, the sleeve inner diameter was 70mm, the outer diameter was 90mm, the oxidation layer was removed by 120 mesh sandpaper rough grinding, the surface roughness reached Ra12.5μm, the oil was removed by acetone ultrasonic cleaning for 5-10 minutes, and then the sample was washed by deionized water and dried.

[0090] Titanium alloy powder TC4 (purity≥99%, particle size 15-53μm) and B4C powder (purity≥99%, particle size 6-10μm) were mixed according to the mass ratio of 99:1, the content of B4C powder in the mixed powder was increased, and the proportion of in-situ reaction generated ceramic phase was increased. The mixed powder was dried at 80℃ for 2 hours to remove water by mechanical mixing method.

[0091] The laser power was set to 1500W during the laser cladding process, increasing the laser power was helpful to the decomposition of B4C to generate [B] and [C], and promoted the in-situ reaction of ceramic phase, the sleeve rotation speed was 5r / min, the powder feeding rate was 1.6r / min, the overlap rate was 40%, the cladding head moved along the direction parallel to the cylindrical surface, and the moving speed was 120mm / min.

[0092] The argon-nitrogen composite gas system was used to realize high-precision powder delivery and reaction control, the argon output pressure was 0.5mbar, and the nitrogen output pressure was 0.5mbar.

[0093] The reaction process in the molten pool during the laser cladding process of example 4 was similar to example 1. Under the action of laser energy field, gas-liquid and solid-liquid double reactions occurred in the molten pool, TiN dendrites were generated by the reaction of molten Ti and active nitrogen, [B] and [C] generated by the decomposition of B4C reacted with Ti to generate TiB2 whiskers and TiC particles, a multi-element synergistic reinforced structure was formed in the coating, and the substrate was solid-solution enhanced by non-metallic elements, which significantly improved the hardness and wear resistance of the coating.

[0094] It should be understood that the application of the present application is not limited to the above examples, and those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes shall belong to the protection scope of the present application.

Claims

1. A method for preparing an in-situ reactive multi-element ceramic phase reinforced titanium-based composite coating, characterized in that, Includes the following steps: Titanium alloy powder and B4C powder are mixed to obtain a mixed powder; The mixed powder is transported to the cladding focal point under a protective atmosphere and a reactive gas is introduced for laser cladding to form the in-situ reactive multi-element ceramic phase reinforced titanium-based composite coating on the surface of the metal sample; the reactive gas is nitrogen; the parameters of the laser cladding are: laser power 1-2kW, scanning speed 5-20mm / s, and multi-pass cladding overlap rate 40%-80%.

2. The method for preparing the in-situ reactive multi-element ceramic phase reinforced titanium-based composite coating according to claim 1, characterized in that, The inlet pressure of the reaction gas is 0.1-0.5 mbar.

3. The method for preparing an in-situ reactive multi-element ceramic phase reinforced titanium-based composite coating according to claim 1, characterized in that, The mixed powder is conveyed to the cladding focal point under argon protection at a powder feeding speed of 0.5-3.0 r / min.

4. The method for preparing the in-situ reactive multi-element ceramic phase reinforced titanium-based composite coating according to claim 1, characterized in that, In the mixed powder, the B4C powder accounts for 1%-5% by mass.

5. The method for preparing an in-situ reactive multi-element ceramic phase reinforced titanium-based composite coating according to claim 1, characterized in that, The titanium alloy powder and the B4C powder are mechanically mixed and dried to obtain the mixed powder.

6. The method for preparing an in-situ reactive multi-element ceramic phase reinforced titanium-based composite coating according to claim 1, characterized in that, The titanium alloy powder comprises one or more of TA, TB, and TC4, with a purity ≥99% and a particle size range of 15-150μm. The B4C powder has a purity of ≥99% and a particle size range of 1-50μm.

7. The method for preparing an in-situ reactive multi-element ceramic phase reinforced titanium-based composite coating according to claim 1, characterized in that, After the surface of the metal sample is pretreated by grinding, sandblasting and cleaning, laser cladding is then performed on the surface to obtain the in-situ reactive multi-element ceramic phase reinforced titanium-based composite coating.

8. An in-situ reactive multi-component ceramic phase reinforced titanium-based composite coating obtained by the preparation method of the in-situ reactive multi-component ceramic phase reinforced titanium-based composite coating according to any one of claims 1-7.

9. The in-situ reactive multi-element ceramic phase reinforced titanium-based composite coating according to claim 8, characterized in that, Including α-Ti matrix phase, β-Ti matrix phase, and multi-component ceramic reinforcing phase; Non-metallic elements are dissolved in the metal sample, forming solid solution strengthening.

10. The in-situ reactive multi-element ceramic phase reinforced titanium-based composite coating according to claim 8, characterized in that, The thickness is 300-1500μm.

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