Waste molybdenum wire fiber reinforced metal coating and laser cladding preparation method thereof

Abstract

The invention discloses a waste molybdenum wire fiber reinforced metal coating and a laser cladding preparation method thereof. The laser cladding preparation method comprises the following steps: cleaning and pretreating waste molybdenum wires and metal powder; the prefabricated body is formed, the prefabricated body is a prefabricated body I or a prefabricated body II, the prefabricated body I is a molybdenum wire fiber prefabricated body independently formed by molybdenum wires, and the prefabricated body II is a molybdenum wire powder prefabricated body formed by the molybdenum wires and metal powder; fixing the prefabricated body on the surface of a to-be-cladded part by adopting a welding, cementing or mechanical method; a coating is prepared through laser cladding, technological parameters are set, reciprocating lap joint scanning is conducted on the upper surface of a prefabricated body through a laser beam, and the prefabricated body forms the molybdenum wire fiber reinforced metal coating on the surface of the to-be-cladded part through the melting action; and post-processing. According to the invention, the strength, toughness and high-temperature performance of the coating are improved by utilizing the high melting point of the metal molybdenum wire, the rapid solidification characteristic of the laser cladding technology and the principles of fiber strengthening and solid solution strengthening, so that the wear resistance and impact resistance of the coating are improved.

Description

Technical Field

[0001] The invention relates to the technical field of surface engineering, and in particular to a method for preparing a metal coating reinforced by waste molybdenum wire fibers and a laser cladding method thereof. Background Art

[0002] Laser cladding refers to the use of a high-energy laser beam to simultaneously melt metal powder and the substrate to form an alloy coating with excellent properties such as high strength and strong plasticity. Laser cladding is divided into synchronous powder feeding method and presetting method. The synchronous powder feeding method refers to the method of using a powder feeder to feed powder into the molten pool while the laser beam acts on the substrate, so that the cladding material and the substrate undergo a metallurgical reaction, and a cladding layer is generated after the molten pool cools down. The presetting method is a method of applying a certain thickness and shape of powder on the surface of the substrate in advance, then using a laser to heat and melt the substrate and the cladding material at the same time, and finally cooling to form a cladding layer. The laser cladding coating has excellent characteristics such as high hardness, corrosion resistance, and good bonding performance with the substrate. Therefore, laser cladding technology has become a rapidly developing coating preparation method with broad application prospects. At present, the use of laser cladding technology to prepare coatings with excellent performance has been widely used in many fields.

[0003] Generally speaking, the wear resistance of laser cladding coatings is positively correlated with hardness. However, due to the lack of toughness, wear-resistant coatings with high hardness are difficult to withstand high-frequency impact loads, which often causes the coating to break and peel off prematurely. In response to this problem, researchers have proposed many solutions. For example, by optimizing process parameters and preheating the substrate surface, the density of the organization can be improved (porosity and crack rate can be reduced) to improve the surface quality of the coating; by optimizing the material composition to improve the coating performance; by constructing a gradient coating, the coating structure can be optimized and the coating performance can be improved. However, the methods of optimizing process parameters and preheating the substrate surface have limited effects on the performance improvement of the coating; the methods of optimizing material composition have problems such as large uncertainty, long research and development cycle of new powders, and high cost; the method of constructing a gradient coating greatly complicates the process and increases the difficulty of controlling process quality.

[0004] A Chinese patent with publication number CN 106694879 B discloses a method for laser-induction composite melting deposition of fiber-reinforced metal matrix composite materials, the characteristics of which are: (1) firstly generating a three-dimensional model of a fiber-reinforced metal matrix composite part, and then using a slicing technique to generate a laser two-dimensional processing path of the part; (2) roughening, sensitizing, activating and chemically plating the fiber to form a nickel plating layer with a thickness of 20 to 50 μm on the surface of the fiber with a diameter of 0.2 to 10 μm; (3) using a fiber weaving template to weave the fibers into a mutually parallel structure; and (4) using a laser-induction composite cladding deposition technique to melt the alloy powder and coat the fibers to form a fiber-reinforced metal matrix composite material. The invention can be used to prepare fiber-reinforced metal matrix composite structural parts under high efficiency and low cost conditions; the fiber is evenly distributed in the metal matrix composite as a reinforcing phase; the fiber structure remains intact and the distance between fibers is adjustable and controllable; the fiber-reinforced metal matrix composite has a dense microstructure, no pores and cracks, a hardness of 1000-1250HV0.2, a dry sliding wear performance of about 3-5 times that of GCr15 with a hardness of 60HRC, a tensile strength of 1000-1200Mpa, and an elongation of 20-45%. However, this method has the following problems:

[0005] (1) The fibers used are carbon fibers, quartz fibers or glass fibers, which are metal-based composite materials commonly used in the prior art, obtained by combining non-metallic materials (such as organic polymer materials, inorganic non-metallic materials, etc.) in the form of particles, fibers, etc. with metal materials.

[0006] (2) The non-metallic fibers are roughened, sensitized, activated and chemically plated. During laser cladding, the molten alloy powder is rapidly solidified and wraps the fibers to form a fiber-reinforced metal-based deposition layer (coating). The technical cost is high and the wear resistance and impact resistance of the coating need to be improved.

[0007] On the other hand, a large amount of waste molybdenum wire is produced in industrial production, such as waste molybdenum wire in wire cutting, waste in molybdenum mesh production, molybdenum wire in waste catalysts, etc. Molybdenum is a rare metal with limited reserves. Recycling and utilizing these molybdenum wires is of great significance to saving resources, promoting circular economy, and reducing environmental pollution. However, there are currently problems such as low recycling rate, narrow recycling scope, and high technical difficulty for waste molybdenum wires.

[0008] Therefore, the present invention proposes a solution for fiber reinforcement of laser cladding metal coating using waste molybdenum wire, which is a new method for recycling waste molybdenum wire, expands the recycling scope of waste molybdenum wire, and also solves the problem of impact resistance of wear-resistant coating. Summary of the invention

[0009] Technical problems to be solved: In view of the problems in the prior art such as low recovery rate of waste molybdenum wire, narrow recycling area, great technical difficulty, poor impact resistance of existing laser cladding metal coatings, and easy premature brittle fracture and peeling, the present invention proposes a fiber-reinforced metal coating using waste molybdenum wire and a laser cladding preparation method thereof, which utilizes the high melting point of metal molybdenum wire and the rapid solidification characteristics of laser cladding technology, as well as the principles of fiber reinforcement and solid solution strengthening, thereby improving the strength, toughness and high-temperature performance of the coating, and improving the wear resistance and impact resistance of the coating.

[0010] Technical solution: One of the purposes of the present invention is to provide a laser cladding preparation method for strengthening a metal coating using waste molybdenum wire fibers, the steps of which are as follows:

[0011] Step 1: Clean and pretreat the waste molybdenum wire and metal powder;

[0012] Step 2, preform forming, the preform is preform I or preform II, preform I is a molybdenum wire fiber preform composed of molybdenum wire alone, preform II is a molybdenum wire powder preform composed of molybdenum wire and metal powder, the preparation method of preform I is as follows: waste molybdenum wire is made into a molybdenum wire fiber mesh structure by weaving or knitting; the preparation method of preform II is as follows: waste molybdenum wire is mixed with metal powder, and the mixture of waste molybdenum wire and metal powder is pressed into a molybdenum wire powder preform by a pressure molding method;

[0013] Step 3: Fix the preform by welding, gluing or mechanically fixing the preform on the surface of the part to be clad;

[0014] Step 4: Prepare the coating by laser cladding. Set the process parameters, including laser power, scanning speed, powder feeding amount and shielding gas flow rate. Use the laser beam to reciprocately overlap and scan the surface above the preform, so that the preform forms a molybdenum wire fiber reinforced metal coating on the surface of the part to be clad through melting and solidification.

[0015] Step 5: Post-processing: heat treatment or mechanical processing of the molybdenum wire fiber reinforced metal coating according to the use requirements of the coating.

[0016] Preferably, in the step 1, the diameter of the waste molybdenum wire is 0.10-0.30 mm, and the melting point of the metal powder is lower than the melting point of metallic molybdenum.

[0017] Preferably, in step 1, the waste molybdenum wire and metal powder are cleaned and pretreated as follows: the waste molybdenum wire is cleaned to remove oil stains, oxide layer and impurities to ensure the smooth progress of subsequent processes, and then dried; the metal powder is mixed and dried.

[0018] Preferably, the cleaning method of the waste molybdenum wire in step 1 includes at least one of alkaline cleaning, ultrasonic cleaning and electrolytic cleaning.

[0019] Preferably, the thickness of the preform in step 2 is 1-2 mm, and the length and width of the preform are comparable to those of the desired coating.

[0020] Furthermore, the thickness of the molybdenum wire metal preform I is slightly smaller than the thickness of the required coating, and the thickness of the molybdenum wire powder preform II is comparable to the thickness of the required coating.

[0021] Preferably, the molybdenum wire fiber mesh structure in step 2 is a regularly ordered periodically distributed molybdenum mesh or a randomly oriented random fiber interwoven mesh after weaving.

[0022] Preferably, in the step three, before fixing the preform, the surface of the part to be clad is firstly polished and cleaned to remove stains and surface contamination of the oxide film; the welding method includes electric seam roll welding and laser spot welding.

[0023] Preferably, in step 4, the process parameters of laser cladding are selected to achieve the goal of complete melting of the metal powder and metallurgical bonding with the surface of the part to be clad, and incomplete melting of the molybdenum wire. When preform I is selected, the synchronous powder feeding method is used for laser cladding, and the powder is the metal powder in step 1; when preform II is selected, since preform II is equivalent to the powder body in the preset powder method, synchronous powder feeding is not required during laser cladding, which is equivalent to laser cladding using the preset method.

[0024] Preferably, the heat treatment in step five includes stress relief annealing and laser remelting, and the mechanical processing includes cutting, grinding, polishing and sand blasting.

[0025] Another object of the present invention is to provide a metal coating reinforced with waste molybdenum wire fibers prepared based on the above method.

[0026] Compared with the existing traditional non-metallic materials combined with metal materials, the biggest technical difficulty of the present invention is how to make the molybdenum wire fiber reinforcement phase controllably and evenly distributed in the coating. The present invention uses waste molybdenum wire to form a preform by weaving or by extruding waste molybdenum wire and metal powder. After the preform is fixed on the surface of the part to be clad, laser cladding is performed to prepare a waste molybdenum wire fiber reinforced metal coating. The present invention utilizes the high melting point of metal molybdenum wire and the characteristics of rapid solidification of laser cladding, and uses a high melting point molybdenum wire and a metal material (usually an iron-based alloy, a nickel-based alloy, a cobalt-based alloy, a high entropy alloy, etc., which has a melting point lower than that of molybdenum wire) to combine, and utilizes the difference in melting points between the two metal materials to achieve partial melting of the molybdenum wire during the laser cladding process, and the metal material (powder) is completely melted to form a fiber composite metal coating. The unmelted part plays a role in fiber reinforcement, and the molybdenum element of the molten part diffuses into the metal matrix. The matrix performance is improved by fiber reinforcement, solid solution reinforcement, second phase reinforcement, etc., so that the wear resistance and impact resistance of the coating are greatly improved.

[0027] Specifically, the fibrous molybdenum wire has a blocking effect and a stress transfer effect at the interface with the coating, which can effectively prevent crack propagation and reduce stress concentration, thereby improving the toughness of the coating. At the same time, due to the synergistic effect of chemical bonding, diffusion bonding and mechanical bonding between the partially molten molybdenum wire and the coating, the interface bonding effect between the two is better, which enhances the stress transfer effect. The refractory metal molybdenum element provided by the partially molten molybdenum wire solid solution strengthens the metal coating and improves the strength and high temperature performance of the coating. The combined effect of the above effects of improving strength, toughness and high temperature performance improves the wear resistance and impact resistance of the coating.

[0028] Beneficial effects:

[0029] (1) The strength, plasticity and wear resistance of the coating prepared by the present invention are improved. By embedding molybdenum wire in the coating, a stable support network is formed in the coating, which can effectively bear the stress during external loading. At the same time, through the load transfer effect, the stress can be dispersed and the stress concentration can be reduced, thereby improving the overall strength, plasticity and wear resistance of the coating.

[0030] (2) The coating prepared by the present invention has good interface bonding effect. The quality of the interface bonding effect directly affects the stress transfer effect. Due to the high melting point of metal molybdenum and the characteristics of rapid cooling of laser cladding, the molybdenum wire is only partially melted. At the interface between the molybdenum wire and the metal coating, the molybdenum element and the metal coating produce an interface reaction to form an interface reaction layer. The chemical bonding formed by the appropriate interface reaction improves the interface bonding strength. At the same time, the metal coating and the molybdenum wire enter each other through atomic diffusion to form a diffusion bond. In addition, the surface of the partially melted molybdenum wire is uneven. During the laser cladding process, the molten metal is impregnated and solidified, and a mechanical anchoring effect is generated. Through the synergistic effect of the three mechanisms, the interface bonding strength between the coating and the molybdenum wire is high, the bonding effect is good, which is conducive to the transfer of stress, thereby improving the strength of the metal coating and the interface bonding effect. It solves the problems of low bonding strength and poor interface wettability at the metal-non-metal bonding interface caused by using non-metallic materials such as carbon fiber and quartz fiber as the fiber reinforcement phase in the metal matrix to make a composite material in the prior art.

[0031] (3) The present invention can save resources and improve resource utilization. The molybdenum wire used in the present invention is waste molybdenum wire produced by wire cutting and the like. Molybdenum is a rare metal with limited reserves. Its reuse has problems such as low recovery rate, narrow recycling area, and high technical difficulty. The present invention provides a new idea for the reuse of waste molybdenum wire, broadens its recycling area, and improves resource utilization, which is in line with the concept of green development.

[0032] (4) The coating prepared by the present invention has low crack sensitivity. During laser cladding, due to the existence of thermal stress, uneven cooling speed of the coating and the parts to be clad, etc., cracks may occur in the cladding layer. Molybdenum wire is embedded in the coating. During the laser cladding process, when the stress of the coating reaches the yield limit of molybdenum, the molybdenum wire preform will yield first, and then release the residual stress in the coating, reducing the generation of cracks. At the same time, due to the interface blocking effect at the bonding interface between the molybdenum wire and the coating, when the crack tip is transmitted to the bonding interface, the molybdenum wire and the metal coating are debonded, and the crack propagates along the interface, passivating the crack tip, thereby hindering the expansion of the crack and reducing the crack sensitivity of the coating.

[0033] (5) The coating prepared by the present invention has good high temperature performance. The molybdenum wire has a high melting point and has good stability at high temperatures. Its strength does not decrease substantially at high temperatures. The molybdenum wire can still stably support and transfer loads at high temperatures, so that the coating has good high temperature performance.

[0034] (6) The raw materials used in the present invention are highly adaptable. Metal powders of various materials such as iron-based alloys, nickel-based alloys, cobalt-based alloys, and high-entropy alloys are all applicable. Since molybdenum is a refractory metal, molybdenum wire has a high melting point, and the melting points of most wear-resistant coating materials are lower than molybdenum wire, the molybdenum wire fiber reinforced coating described in the present invention can be achieved by selecting reasonable laser cladding process parameters.

[0035] (7) The present invention adopts a preform molding method to produce a multi-layer molybdenum wire fiber preform or a molybdenum wire powder preform, which effectively solves the problems of powder feeding blockage and serious aggregation of the fiber reinforcement phase in the coating under conventional coaxial powder feeding methods of molybdenum wire fibers, and at the same time makes the fiber reinforcement phase controllably and evenly distributed in the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The schematic diagram of the structure of the device for preparing a metal coating reinforced by waste molybdenum wire fiber by laser cladding of the present invention, wherein (a) is a front view with a workbench at the bottom; (b) is a top view of the device without a workbench;

[0037] Figure 2 This is a schematic diagram of the cross-section of the coating of the laser cladding molybdenum wire powder preform II of the present invention;

[0038] Figure 3 This is a schematic diagram of the cross-section of the coating of the laser cladding molybdenum wire fiber preform I of the present invention;

[0039] Figure 4 The present invention is a flow chart of a laser cladding preparation method for strengthening a metal coating using waste molybdenum wire fibers.

[0040] The numbers in the figure represent the following: 1. Laser cladding head; 2. Parts to be clad; 3. Workbench; 4. Laser welding point; 5. Preform; 6. Coating; 7. Molybdenum wire. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0042] A laser cladding preparation method using waste molybdenum wire fiber to strengthen metal coating, see Figure 4 , the steps are as follows:

[0043] Step 1: Clean and pretreat the waste molybdenum wire and metal powder;

[0044] Step 2, preform forming, the preform is preform I or preform II, preform I is a molybdenum wire fiber preform composed of molybdenum wire alone, preform II is a molybdenum wire powder preform composed of molybdenum wire and metal powder, the preparation method of preform I is as follows: waste molybdenum wire is made into a molybdenum wire fiber mesh structure with thickness by weaving or knitting; the preparation method of preform II is as follows: waste molybdenum wire is mixed with metal powder, and the mixture of waste molybdenum wire and metal powder is pressed into a molybdenum wire powder preform with thickness by a pressure molding method;

[0045] Step 3: Fix the preform by welding, gluing or mechanically fixing the preform on the surface of the part to be clad;

[0046] Step 4: Prepare the coating by laser cladding. Set the process parameters, including laser power, scanning speed, powder feeding amount and shielding gas flow rate. Use the laser beam to reciprocately overlap and scan the surface above the preform, so that the preform forms a molybdenum wire fiber reinforced metal coating on the surface of the part to be clad through melting and solidification.

[0047] Step 5: Post-processing: heat treatment or mechanical processing of the molybdenum wire fiber reinforced metal coating according to the use requirements of the coating.

[0048] As one of the preferred embodiments of the present invention, see Figure 1 In step 4, when preparing the coating by laser cladding, the part 2 to be clad is placed on the workbench 3, the laser cladding head 1 is set above the part 2 to be clad, and the preform 5 is fixed to the part 2 to be clad by welding (laser spot welding or electric seam roll welding). Then the laser cladding head 1 is connected to a high-power laser, and the laser beam and metal powder (preform II does not need metal powder) are transmitted to the surface area of ​​the part 2 to be clad where the preform 5 is fixed through the laser cladding head 1 to complete the preparation of the coating.

[0049] As one of the preferred embodiments of the present invention, the diameter of the waste molybdenum wire in step 1 is 0.10-0.30 mm, and the melting point of the metal powder is lower than the melting point of metallic molybdenum.

[0050] As one of the preferred embodiments of the present invention, the cleaning and pretreatment of the waste molybdenum wire and metal powder in step one are specifically as follows: the waste molybdenum wire is cleaned to remove oil stains, oxide layer and impurities to ensure the smooth progress of subsequent processes, and then dried; the metal powder is mixed and dried.

[0051] As one of the preferred embodiments of the present invention, the cleaning method of the waste molybdenum wire in step one includes at least one of alkaline cleaning, ultrasonic cleaning and electrolytic cleaning.

[0052] As one of the preferred embodiments of the present invention, the thickness of the preform in step 2 is 1-2 mm, and the length and width of the preform are comparable to the length and width of the required coating.

[0053] Furthermore, the thickness of the molybdenum wire metal preform I is slightly smaller than the thickness of the required coating, and the thickness of the molybdenum wire powder preform II is comparable to the thickness of the required coating.

[0054] As one of the preferred embodiments of the present invention, the molybdenum wire fiber mesh structure in step 2 is a regularly ordered periodically distributed molybdenum mesh or a randomly oriented random fiber interwoven mesh after weaving.

[0055] As one of the preferred embodiments of the present invention, in the step three, before fixing the preform, the surface of the part to be clad is first polished and cleaned to remove stains and surface contamination of the oxide film; the welding method includes electric seam roll welding and laser spot welding.

[0056] As one of the preferred embodiments of the present invention, in step 4, the laser cladding aims to completely melt the metal powder and metallurgically bond it with the surface of the part to be clad, and the molybdenum wire is not completely melted. When preform I is selected, the laser cladding is performed by the synchronous powder feeding method, and the powder is the metal powder in step 1; when preform II is selected, the laser cladding is performed by the preset method, and synchronous powder feeding is not required.

[0057] As one of the preferred embodiments of the present invention, the heat treatment in step five includes stress relief annealing and laser remelting, and the mechanical processing includes cutting, grinding, polishing and sand blasting.

[0058] A metal coating reinforced with waste molybdenum wire fibers is prepared based on the above method.

[0059] The specific embodiments are as follows:

[0060] Example 1

[0061] This embodiment utilizes Figure 1 The device shown in the figure realizes a laser cladding preparation method for strengthening a metal coating using waste molybdenum wire fibers. The preform of this embodiment is selected as preform II, see Figure 4 , the specific steps are as follows:

[0062] Step 1, cleaning and pretreatment: Select waste molybdenum wire with a diameter of 0.18mm, place it in a 30% NaOH solution, heat it to 50℃ for alkali washing for 3 hours, take it out and rinse it, put it in anhydrous ethanol for ultrasonic cleaning, take it out after 10 minutes, and dry it. Select CoCrFeMnNi high entropy alloy powder (produced by Jiangsu Willari New Materials Technology Co., Ltd., the composition of the powder (at.%): Co Bal.; Cr 20.1; Fe 20.09; Mn 19.85; Ni 20.08.), place it in a vacuum drying oven, heat it to 100℃ and dry it for 1h, then take it out for use. Grind the surface of the part 2 to be clad with an angle grinder and clean it with anhydrous ethanol.

[0063] Step 2, preform molding: weigh 10g of waste molybdenum wire with a diameter of 0.18mm, cut it into a length of 10mm-30mm, mix it evenly with 90g of CoCrFeMnNi high entropy alloy powder, and place it in a cylindrical mold with a diameter of 40mm. Use a press to extrude the mixture of the two into a molybdenum wire powder preform 5 with a thickness of 2mm.

[0064] Step 3, fix the preform: place the part 2 to be clad on the workbench 3, and the laser cladding head 1 is set above the part 2 to be clad. Place a circular molybdenum wire powder preform 5 with a diameter of 40 mm on the surface of the part 2 to be clad. Use laser spot welding to fix the molybdenum wire powder preform 5 on the surface of the part 2 to be clad through the laser welding point 4.

[0065] Step 4, laser cladding coating: laser cladding is performed under the protection of argon gas. Since the preform 5 contains metal powder, synchronous powder feeding is not required. The laser cladding head 1 is connected to a high-power laser, and the laser beam is transmitted to the surface area of ​​the part 2 to be clad with the preform 5 fixed thereon through the laser cladding head 1. After optimizing the process parameters, the laser power is set to 1.3kW, the scanning speed is 3mm / s, the defocus amount is +12mm, the protective gas flow rate is 7L / min, and the coating overlap rate is 40%. Laser cladding is performed to complete the preparation of the coating. At this time, the metal powder is completely melted and metallurgically bonded to the surface of the part to be clad, and the molybdenum wire is not completely melted.

[0066] Step 5, post-processing: grind the surface of the machined workpiece to make it smooth, and place it in a vacuum annealing furnace at 500°C for stress relief annealing for 6 hours to meet its working requirements.

[0067] like Figure 2 The figure shows a schematic cross-sectional view of the prepared coating, wherein 2 is the part to be clad, and the partially melted molybdenum wire 7 is evenly distributed in the coating 6 in a random orientation.

[0068] Example 2

[0069] This embodiment utilizes Figure 1 The device shown in the figure realizes a laser cladding preparation method for strengthening a metal coating using waste molybdenum wire fibers. The preform of this embodiment is selected as preform I, see Figure 4 , the specific steps are as follows:

[0070] Step 1, cleaning and pretreatment. Select waste molybdenum wire with a diameter of 0.18mm, place it in a 30% NaOH solution by mass, heat it to 50℃ for alkali washing for 3 hours, take it out and rinse it, put it in anhydrous ethanol for ultrasonic cleaning, take it out after 10 minutes, and dry it. Select AlCoCrFeNi high entropy alloy powder (produced by Jiangsu Willari New Materials Technology Co., Ltd., the composition of the powder (at.%) is Co Bal.; Cr 19.95; Fe 19.50; Ni 19.76; Al 19.94), place it in a vacuum drying oven, heat it to 100℃ and dry it for 1h, then take it out for use, and grind the surface of the cladding part 2 with an angle grinder and clean it with anhydrous ethanol.

[0071] Step 2, preform forming: weigh 100g of cleaned waste molybdenum wire with a diameter of 0.18mm, and use a braiding machine to weave the waste molybdenum wire into an ordered periodically distributed multi-layer molybdenum mesh structure (such as Figure 1 As shown in (b), a simple mesh structure with 6-10 layers, adjusted according to actual conditions, and a thickness of 1-2 mm) is made into a molybdenum wire fiber preform.

[0072] Step 3, fix the preform: place the part 2 to be clad on the workbench 3, and the laser cladding head 1 is set above the part 2 to be clad. Place a molybdenum wire fiber preform 5 with a size of 100mm×100mm on the surface of the part 2 to be clad. Fix the molybdenum wire fiber preform 5 on the surface of the part 2 to be clad by electric seam rolling welding.

[0073] Step 4, laser cladding coating: connect the laser cladding head 1 to a high-power laser, transmit the laser beam and metal powder to the surface area of ​​the part 2 to be clad with the preform 5 fixed thereon through the laser cladding head 1, perform laser cladding under the protection of argon, use AlCoCrFeNi high entropy alloy powder, laser power 1.5kW, powder feeding amount 10g / min, scanning speed 5mm / s, defocusing amount +12mm, shielding gas flow 7L / min, coating overlap rate 40%. The coating is prepared on the surface of the workpiece to be fixed with the molybdenum wire fiber preform by synchronous powder feeding, at which time the metal powder is completely melted and metallurgically bonded to the surface of the part to be clad, and the molybdenum wire is not completely melted.

[0074] Step 5, post-processing: Grind the surface of the finished workpiece to make it smooth to meet its working requirements.

[0075] like Figure 3The figure shows a schematic cross-sectional view of the prepared coating, wherein 2 is the part to be clad, and the partially melted molybdenum wires 7 are evenly and regularly arranged in the coating 6.

[0076] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned implementation modes, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned implementation modes can still be modified, or some or all of the technical features therein can be replaced by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the implementation modes of the present invention.

Claims

1. A laser cladding preparation method for strengthening metal coating using waste molybdenum wire fibers, characterized in that: Here are the steps: Step 1: Clean and pretreat the waste molybdenum wire and metal powder; Step 2, preform forming, the preform is preform I or preform II, preform I is a molybdenum wire fiber preform composed of molybdenum wire alone, preform II is a molybdenum wire powder preform composed of molybdenum wire and metal powder, the preparation method of preform I is as follows: waste molybdenum wire is made into a molybdenum wire fiber mesh structure by weaving or knitting; the preparation method of preform II is as follows: waste molybdenum wire is mixed with metal powder, and the mixture of waste molybdenum wire and metal powder is pressed into a molybdenum wire powder preform by a pressure molding method; Step 3: Fix the preform by welding, gluing or mechanically fixing the preform on the surface of the part to be clad; Step 4: Prepare the coating by laser cladding. Set the process parameters, including laser power, scanning speed, powder feeding amount and shielding gas flow rate. Use the laser beam to reciprocately overlap and scan the surface above the preform, so that the preform forms a molybdenum wire fiber reinforced metal coating on the surface of the part to be clad through melting and solidification. Step 5: Post-processing: heat treatment or mechanical processing of the molybdenum wire fiber reinforced metal coating according to the use requirements of the coating.

2. The laser cladding preparation method of using waste molybdenum wire fiber to strengthen the metal coating according to claim 1 is characterized in that: In the step 1, the diameter of the waste molybdenum wire is 0.10-0.30 mm, and the melting point of the metal powder is lower than the melting point of metal molybdenum.

3. The laser cladding preparation method of using waste molybdenum wire fiber to strengthen metal coating according to claim 1 is characterized in that: In the step 1, the waste molybdenum wire and the metal powder are cleaned and pretreated as follows: the waste molybdenum wire is cleaned to remove oil stains, oxide layers and impurities, and then dried; and the metal powder is mixed and dried.

4. The laser cladding preparation method for strengthening metal coating using waste molybdenum wire fibers according to claim 3 is characterized in that: The cleaning method of the waste molybdenum wire in step 1 includes at least one of alkaline cleaning, ultrasonic cleaning and electrolytic cleaning.

5. The laser cladding preparation method of using waste molybdenum wire fiber to strengthen metal coating according to claim 1, characterized in that: The thickness of the preform in step 2 is 1-2 mm, and the length and width of the preform are equivalent to the length and width of the required coating.

6. The laser cladding preparation method of using waste molybdenum wire fiber to strengthen metal coating according to claim 1 is characterized in that: The molybdenum wire fiber mesh structure in step 2 is a molybdenum mesh with regular, orderly and periodic distribution after weaving or a randomly oriented random fiber interwoven mesh.

7. The laser cladding preparation method of using waste molybdenum wire fiber to strengthen metal coating according to claim 1 is characterized in that: In the step three, before fixing the preform, the surface of the part to be clad is first polished and cleaned to remove stains and surface contamination of the oxide film; the welding method includes electric seam roll welding and laser spot welding.

8. The laser cladding preparation method for strengthening metal coating using waste molybdenum wire fibers according to claim 1 is characterized in that: In the step 4, the laser cladding aims to completely melt the metal powder and metallurgically bond it to the surface of the part to be clad, and the molybdenum wire is not completely melted. When preform I is selected, the laser cladding is performed by the synchronous powder feeding method, and the powder is the metal powder in step 1; when preform II is selected, the laser cladding is performed by the preset method, and synchronous powder feeding is not required.

9. The laser cladding preparation method of using waste molybdenum wire fiber to strengthen metal coating according to claim 1, characterized in that: The heat treatment in step five includes stress relief annealing and laser remelting, and the mechanical processing includes cutting, grinding, polishing and sand blasting.

10. A metal coating reinforced with waste molybdenum wire fibers prepared by the method according to any one of claims 1 to 9.

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