A metal coating reinforced by waste molybdenum wire fiber and a laser cladding preparation method thereof

Abstract

The application discloses a kind of metal coating reinforced by waste molybdenum wire fiber and its laser cladding preparation method, steps are as follows: waste molybdenum wire and metal powder are cleaned and pretreated;Preform forming, the preform is preform I or preform II, preform I is the molybdenum wire fiber preform that is formed by molybdenum wire alone, preform II is the molybdenum wire powder preform that is formed by molybdenum wire and metal powder;Preform is fixed to the surface of the part to be cladded using welding, adhesive bonding or mechanical method;Laser cladding preparation coating, set process parameters, reciprocating lap scanning is carried out on the top surface of preform using laser beam, so that preform forms molybdenum wire fiber reinforced metal coating on the surface of the part to be cladded by fusion effect;Post-processing.The application utilizes the high melting point of metal molybdenum wire and the characteristics of rapid solidification of laser cladding technology, as well as the principle of fiber reinforcement and solid solution strengthening, improves the strength, toughness and high temperature performance of the coating, so that the wear resistance and impact resistance of the coating are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of surface engineering, in particular to a kind of metal coating reinforced by waste molybdenum wire fiber and its laser cladding preparation method. BACKGROUND

[0002] Laser cladding refers to the use of high-energy laser beams to melt metal powder and substrate simultaneously, forming alloy coating with excellent properties such as high strength and high plasticity. Laser cladding is divided into synchronous powder feeding method and preposition method. Synchronous powder feeding method refers to the method of using powder feeder to send powder into the molten pool while the laser beam acts on the substrate, so that the cladding material and the substrate undergo metallurgical reaction, and the cladding layer is formed after the molten pool cools down. Preposition method is to apply a certain thickness and shape of powder on the surface of the substrate first, then use laser to heat and melt the substrate and cladding material at the same time, and finally cool to form a cladding layer. Laser cladding coating has excellent properties such as high hardness, corrosion resistance, and good bonding performance with the substrate. Therefore, laser cladding technology has become a rapidly developing and widely applicable coating preparation method. Currently, laser cladding technology is widely used in many fields to prepare coatings with excellent performance.

[0003] Generally, the wear resistance of laser cladding coating is positively correlated with hardness. However, high-hardness wear-resistant coatings are difficult to withstand high-frequency impact loads due to the lack of toughness, which often leads to premature brittle fracture and peeling of the coating. To solve this problem, researchers have proposed many solutions. For example, by optimizing process parameters, preheating the substrate surface, etc., to improve the density of the structure (reduce porosity and crack rate), to improve the surface quality of the coating; by optimizing material composition to improve the performance of the coating; by constructing gradient coating to optimize the structure of the coating and improve the performance of the coating. However, the methods of optimizing process parameters and preheating the substrate surface have limited effect on improving the performance of the coating; the method of optimizing material composition has the problems of great uncertainty, long development cycle of new powder, high cost, etc.; the method of constructing gradient coating greatly complicates the process and increases the difficulty of controlling the quality of the process.

[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 material. The method has the following features: (1) a three-dimensional model of the fiber reinforced metal matrix composite part is first generated, and then a two-dimensional laser processing path of the part is generated by using the slicing technology; (2) the fiber is roughened, sensitized, activated and chemically plated to form a nickel plating layer with a thickness of 20-50 μm on the surface of the fiber with a diameter of 0.2-10 μm; (3) the fiber is woven into a parallel structure by using a fiber weaving template; and (4) the alloy powder is melted and the fiber is covered to form the fiber reinforced metal matrix composite material by using the laser-induction composite cladding deposition technology. The structure of the fiber reinforced metal matrix composite material can be prepared under the conditions of high efficiency and low cost by using the method. The fiber as the reinforcing phase is uniformly distributed in the metal matrix composite material. The fiber structure remains intact and the distance between the fibers is adjustable and controllable. The microstructure of the fiber reinforced metal matrix composite material is dense without pores and cracks. The hardness can reach 1000-1250 HV0.2. The dry sliding wear performance is about 3-5 times that of GCr15 with a hardness of 60 HRC. The tensile strength can reach 1000-1200 MPa, and the elongation is 20-45%. However, the method has the following problems:

[0005] (1) The fiber used is carbon fiber, quartz fiber or glass fiber, which belongs to the metal matrix composite material obtained by combining non-metallic materials (such as organic high polymer materials, inorganic non-metallic materials, etc.) in the form of particles, fibers, etc. with metal materials.

[0006] (2) The non-metallic fiber is roughened, sensitized, activated and chemically plated to rapidly solidify the molten alloy powder and wrap the fiber in the laser cladding to form a fiber reinforced metal matrix 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 generated in industrial production on a daily basis, such as waste molybdenum wire in wire cutting processing, waste in molybdenum mesh production, molybdenum wire in waste catalyst, etc. Molybdenum is a rare metal with limited reserves. Recycling and utilizing these molybdenum wires have important significance for saving resources, promoting circular economy and reducing environmental pollution. However, there are problems such as low recovery rate, narrow recycling range and high technical difficulty in recycling the waste molybdenum wire.

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

[0009] Technical problems to be solved: In view of the problems of low recycling rate of waste molybdenum wire, narrow recycling scope, high technical difficulty, poor impact resistance and easy premature brittle fracture and peeling of existing laser cladding metal coatings, this invention proposes a fiber-reinforced metal coating made from waste molybdenum wire and its laser cladding preparation method. By utilizing the high melting point of molybdenum wire and the rapid solidification characteristics of laser cladding technology, as well as the principles of fiber reinforcement and solid solution reinforcement, the strength, toughness and high temperature performance of the coating are improved, thereby improving the wear resistance and impact resistance of the coating.

[0010] Technical solution: One objective of this invention is to provide a laser cladding method for preparing a metal coating reinforced with waste molybdenum wire fibers, the steps of which are as follows:

[0011] Step 1: Clean and pre-treat the waste molybdenum wire and metal powder;

[0012] Step 2: Preform Forming. The preform is either Preform I or Preform II. Preform I is a molybdenum fiber preform composed solely of molybdenum wire, and Preform II is a molybdenum 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 fiber mesh structure by spinning or weaving. 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 powder preform by pressure molding.

[0013] Step 3: Fix the precast body by welding, gluing or mechanical methods to fix the precast body to the surface of the part to be clad;

[0014] Step 4: Laser cladding to prepare the coating. Set the process parameters, including laser power, scanning speed, powder feed rate and protective gas flow rate. Use the laser beam to scan the surface above the preform repeatedly, so that the preform forms a molybdenum fiber reinforced metal coating on the surface of the part to be clad through melting and solidification.

[0015] Step 5: Post-processing. Depending on the application requirements of the coating, the molybdenum fiber reinforced metal coating is subjected to heat treatment or machining.

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

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

[0018] As preferred, the cleaning method of the waste molybdenum wire in step one comprises at least one of alkali cleaning, ultrasonic cleaning and electrolytic cleaning.

[0019] As preferred, the thickness of the preform in step two is 1-2mm, and the length and width of the preform are equivalent to the length and width of the desired coating.

[0020] Further, the thickness of the molybdenum wire preform I is slightly smaller than the thickness of the desired coating, and the thickness of the molybdenum wire powder preform II is equivalent to the thickness of the desired coating.

[0021] As preferred, the molybdenum wire fiber network structure in step two is a regular ordered periodic distribution of molybdenum mesh after weaving or a random orientation of a disordered fiber interlaced mesh.

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

[0023] As preferred, in step four, the process parameters of laser cladding are selected to completely melt the metal powder and metallurgically combine with the surface of the part to be cladded, and the target is that the molybdenum wire is not completely melted; when preform I is selected, synchronous powder feeding is used for laser cladding, and the powder is the metal powder in step one; when preform II is selected, since preform II is equivalent to the powder body in the pre-placed powder method, synchronous powder feeding is not required during laser cladding, which is equivalent to using the pre-placed method for laser cladding.

[0024] As preferred, in step five, the heat treatment comprises stress relief annealing and laser remelting, and the mechanical processing comprises cutting, polishing, polishing and sandblasting.

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

[0026] The biggest technical difficulty of the present application compared with the existing conventional non-metallic material combined metal material is how to make the molybdenum wire fiber reinforcing phase controllably and uniformly distributed in the coating. The present application uses waste molybdenum wire to form a preform by braiding or extruding the waste molybdenum wire and metal powder. After fixing the preform on the surface of the part to be cladded, laser cladding is carried out to prepare a waste molybdenum wire fiber reinforced metal coating. The present application uses the high melting point of the metal molybdenum wire and the characteristics of rapid solidification of laser cladding, combines the high melting point molybdenum wire with metal materials (usually iron-based alloy, nickel-based alloy, cobalt-based alloy, high-entropy alloy, etc. with lower melting point than molybdenum wire), uses the difference in melting point between the two metal materials, so that the molybdenum wire part is melted and solidified, and the metal material (powder) is completely melted, forming a fiber composite metal coating. The unmelted part plays a fiber reinforcement role, and the melted molybdenum element diffuses into the metal matrix, improving the matrix performance through fiber reinforcement, solid solution strengthening, and second phase strengthening, greatly improving the wear resistance and impact resistance of the coating.

[0027] Specifically, the fibrous molybdenum wire has a blocking effect and a stress transfer effect at the bonding interface with the coating, which can effectively prevent crack propagation and slow down stress concentration, thereby improving the toughness of the coating. At the same time, the partial melting of the molybdenum wire and the coating due to the synergistic effect of chemical bonding, diffusion bonding and mechanical bonding makes the interface bonding effect better, and enhances the stress transfer effect. The partial melting of the molybdenum wire provides refractory metal molybdenum element solid solution strengthening of the metal coating, improving the strength and high temperature performance of the coating. The comprehensive effect of the above effects of strength, toughness and high temperature performance improvement improves the wear resistance and impact resistance of the coating.

[0028] Advantages:

[0029] (1) The strength, plasticity and wear resistance of the coating prepared by the present application are improved. By embedding molybdenum wire in the coating, a stable support network is formed in the coating, which can effectively bear the stress under 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 prepared coating has good interface bonding effect. The good or bad of the interface bonding effect directly affects the stress transfer effect. Due to the high melting point of the metal molybdenum and the characteristics of the rapid cooling of the laser cladding, the molybdenum wire is only partially fused, at the bonding interface between the molybdenum wire and the metal coating, the molybdenum element and the metal coating produce interface reaction to form an interface reaction layer, and 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 diffusion bonding. In addition, the surface of the partially fused molybdenum wire is uneven, and during the laser cladding process, the molten metal is immersed and solidified to produce a mechanical anchoring effect. 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 beneficial to the transfer of stress, thereby improving the strength of the metal coating and the interface bonding effect. The problems of low bonding strength and poor interface wettability at the bonding interface between the metal and the non-metal in the prior art are solved.

[0031] (3) The present application can save resources and improve resource utilization. The molybdenum wire used in the present application is waste molybdenum wire generated by wire cutting. Molybdenum is a rare metal with limited reserves, and its recycling has the problems of low recovery rate, narrow recycling range and high technical difficulty. The present application provides a new idea for the recycling of waste molybdenum wire, widens the recycling range, improves the utilization rate of resources, and meets the green development concept.

[0032] (4) The coating prepared by the present application has low crack sensitivity. In the laser cladding process, due to the existence of thermal stress, uneven cooling speed of the coating and the part to be cladded, etc., cracks may be generated in the cladding layer. In the present application, the molybdenum wire is embedded in the coating, and when the stress of the coating reaches the yield limit of molybdenum during the laser cladding process, the molybdenum wire preform will first yield 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 reaches the bonding interface, the molybdenum wire and the metal coating debond, the crack propagates along the interface, and the crack tip is passivated, so that the crack propagation is blocked, and the crack sensitivity of the coating is reduced.

[0033] (5) The coating prepared by the present application has good high-temperature performance. The melting point of the molybdenum wire is high, and it has good stability at high temperature, and its strength does not decrease at high temperature. The molybdenum wire can still stably support and transfer load at high temperature, so that the coating has good high-temperature performance.

[0034] (6) The raw material adopted by the present application is adaptable. The metal powder of various materials such as iron-based alloy, nickel-based alloy, cobalt-based alloy and high-entropy alloy is applicable. Since molybdenum is a refractory metal, the melting point of molybdenum wire is high, and the melting points of most wear-resistant coating materials are lower than that of molybdenum wire, so that the molybdenum wire fiber reinforced coating described in the present application can be realized by selecting reasonable laser cladding process parameters.

[0035] (7) The present application adopts the method of preform forming to make a multilayer molybdenum wire fiber preform or a molybdenum wire powder preform, effectively solving the problems of powder feeding blockage and serious fiber reinforcement phase segregation in the coating under the conventional coaxial powder feeding means, and making the fiber reinforcement phase controllably and uniformly distributed in the coating. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 Figure (a) is a front view, and the bottom is a workbench; (b) is a device top view without a workbench;

[0037] Figure 2 Figure (a) is a front view, and the bottom is a workbench; (b) is a device top view without a workbench;

[0038] Figure 3 Figure (a) is a front view, and the bottom is a workbench; (b) is a device top view without a workbench;

[0039] Figure 4 Figure (a) is a front view, and the bottom is a workbench; (b) is a device top view without a workbench;

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

[0041] The present application will be further described below in combination with the drawings and specific embodiments.

[0042] A laser cladding preparation method for a metal coating reinforced by waste molybdenum wire fiber, as shown in Figure 4 , the steps are as follows:

[0043] Step one, clean and pretreat the waste molybdenum wire and metal powder;

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

[0045] Step three, fixing the preform, the preform is fixed on the surface of the part to be cladded by welding, gluing or mechanical method;

[0046] Step four, laser cladding to prepare the coating, setting the process parameters, including laser power, scanning speed, powder feeding amount and protective gas flow, reciprocating lap scanning the surface of the preform with a laser beam, so that the preform forms a molybdenum wire fiber reinforced metal coating on the surface of the part to be cladded by fusion;

[0047] Step five, post-processing, according to the use requirement of the coating, the molybdenum wire fiber reinforced metal coating is heat treated or machined.

[0048] As one of the preferred embodiments of the present application, referring to Figure 1 , in step four, the part to be cladded 2 is placed on the workbench 3, the laser cladding head 1 is arranged above the part to be cladded 2, and the preform 5 is fixed on the part to be cladded 2 by welding (laser spot welding or electric seam roll welding). Then the laser cladding head 1 is connected with a high-power laser, the laser beam and the metal powder (the preform II does not need metal powder) are transmitted to the surface area of the part to be cladded 2 where the preform 5 is fixed by the laser cladding head 1, and the preparation of the coating is completed.

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

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

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

[0052] As one of the preferred embodiments of the present application, the thickness of the preform in step two is 1-2 mm, and the length and width of the preform are equivalent to the length and width of the desired coating.

[0053] Further, the thickness of the molybdenum wire metal preform I is slightly smaller than the thickness of the desired coating, and the thickness of the molybdenum wire powder preform II is equivalent to the thickness of the desired coating.

[0054] As one of the preferred embodiments of the present application, the molybdenum wire fiber network structure in step two is a regular ordered periodic distribution of molybdenum mesh after weaving or a random orientation of a tangled fiber interwoven mesh.

[0055] As one of the preferred embodiments of the present application, in step three, before fixing the preform, the surface of the part to be cladded is 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 application, in step four, the laser cladding is aimed at complete melting of the metal powder and metallurgical bonding with the surface of the part to be cladded, and incomplete melting of the molybdenum wire, when preform I is selected, the laser cladding is carried out by using the synchronous powder feeding method, and the powder is the metal powder in step one; when preform II is selected, the laser cladding is carried out by using the preposition method, and there is no need for synchronous powder feeding.

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

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

[0059] The specific implementation is as follows:

[0060] Example 1

[0061] This embodiment uses Figure 1 The device shown in the figure realizes a laser cladding preparation method of a metal coating reinforced by waste molybdenum wire fiber, and the preform of this embodiment is preform II, as shown in Figure 4 , the specific steps are as follows:

[0062] Step 1, cleaning and pretreatment: select the diameter of 0.18 mm of waste molybdenum wire, and place it in the mass fraction of 30% NaOH solution, heated to 50℃ alkali washing 3 hours, after taking out and flushing clean, put into anhydrous ethanol ultrasonic cleaning, 10 minutes after taking out, drying. Select CoCrFeMnNi high-entropy alloy powder (produced by Jiangsu Weilali New Material Technology Co., Ltd., the composition of the powder (at.%) is: Co Bal.; Cr 20.1; Fe 20.09; Mn 19.85; Ni 20.08.), placed in a vacuum drying oven, heated to 100℃ drying 1h after taking out for use. The surface of the part to be cladded 2 is polished using an angle grinder and cleaned with anhydrous ethanol.

[0063] Step 2, preform forming: weigh 10g of 0.18mm diameter of waste molybdenum wire, cut to 10mm-30mm length, mix with 90g of CoCrFeMnNi high-entropy alloy powder, then place in a 40mm diameter cylindrical mold, extruded by a press, and the mixture is pressed into a 2mm thick molybdenum wire powder preform 5.

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

[0065] Step 4, laser cladding coating: laser cladding is carried out under the protection of argon. Since the preform 5 contains metal powder, there is no need for synchronous powder feeding. Connect the laser cladding head 1 with the high-power laser, transmit the laser beam to the surface area of the part to be cladded 2 with the preform 5 fixed on it through the laser cladding head 1, and after optimizing the process parameters, set the laser power to 1.3kW, the scanning speed to 3mm / s, the defocusing amount to +12mm, the protective gas flow to 7L / min, and the coating overlap rate to 40%, then carry out laser cladding to complete the preparation of the coating. At this time, the metal powder is completely melted and metallurgically combined with the surface of the part to be cladded, and the molybdenum wire is not completely melted.

[0066] Step 5, post-processing: polish the surface of the finished workpiece smooth, and place it in a vacuum annealing furnace at 500℃ for 6h to meet its working requirements.

[0067] As Figure 2 shown is a cross-sectional view of the prepared coating, wherein 2 is the part to be cladded, and the partially fused molybdenum wire 7 is evenly distributed in the coating 6 with random orientation.

[0068] Example 2

[0069] This example usesFigure 1 The device shown implements a laser cladding preparation method using waste molybdenum wire fiber reinforced metal coating. The preform of the present embodiment is 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 0.18 mm, place it in a 30% NaOH solution, heat to 50°C and alkali wash for 3 hours, then rinse and dry, and then ultrasonic cleaning in anhydrous ethanol, take out after 10 minutes, and dry. Select AlCoCrFeNi high-entropy alloy powder (produced by Jiangsu Weilali New Material 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 box, heat to 100°C and dry for 1h, then take out and use an angle grinder to polish the surface of the cladding part 2 and clean it with anhydrous ethanol.

[0071] Step 2, preform forming: weigh 100g of cleaned waste molybdenum wire with a diameter of 0.18mm, use a braiding machine to braid the waste molybdenum wire into a 100mm x 100mm size ordered periodic distribution of multi-layer molybdenum net structure (such as Figure 1 (b) shown, simple mesh structure, the number of layers is 6-10 layers, adjusted according to actual conditions, thickness is 1-2mm), to make a molybdenum wire fiber preform.

[0072] Step 3, fix the preform: place the cladding part 2 on the workbench 3, and set the laser cladding head 1 above the cladding part 2. Place the 100mm x 100mm size molybdenum wire fiber preform 5 on the surface of the cladding part 2. Use the electric seam roll welding method to fix the molybdenum wire fiber preform 5 on the surface of the cladding part 2.

[0073] Step 4, laser cladding coating: connect the laser cladding head 1 with the high-power laser, transmit the laser beam and metal powder to the surface area of the cladding part 2 with the preform 5 fixed through the laser cladding head 1, and 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, protective gas flow 7L / min, coating overlap rate 40%. Prepare the coating on the surface of the workpiece with the molybdenum wire fiber preform fixed by synchronous powder feeding. At this time, the metal powder is completely melted and metallurgically combined with the surface of the cladding part, and the molybdenum wire is not completely melted.

[0074] Step 5, post-processing: polish the surface of the finished workpiece to meet the working requirements.

[0075] As Figure 3The cross section of the prepared coating is shown, wherein 2 is a part to be cladded, and the partially fused molybdenum wire 7 is uniformly and regularly arranged in the coating 6.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing laser cladding of metal coating reinforced by waste molybdenum wire fiber, characterized in that, The steps are as follows: Step one: cleaning and pretreating the waste molybdenum wire and metal powder, the diameter of the waste molybdenum wire is 0.10-0.30mm, and the melting point of the metal powder is less than that of molybdenum; Step two: forming the preform, the preform is preform I or preform II, preform I is a molybdenum wire fiber preform composed of molybdenum wire alone, and preform II is a molybdenum wire powder preform composed of molybdenum wire and metal powder, the preparation method of preform I is as follows: the waste molybdenum wire is made into a molybdenum wire fiber network structure by weaving or braiding; the preparation method of preform II is as follows: the waste molybdenum wire is mixed in the metal powder, and the mixture of the waste molybdenum wire and the metal powder is pressed into a molybdenum wire powder preform by pressure forming method; Step three: fixing the preform, the preform is fixed on the surface of the part to be cladded by welding, gluing or mechanical method; Step four: preparing the coating by laser cladding, setting the process parameters, including laser power, scanning speed, powder feeding amount and protective gas flow, reciprocating lap scanning on the top surface of the preform with the laser beam, so that the preform forms a molybdenum wire fiber reinforced metal coating on the surface of the part to be cladded by fusion, and the laser cladding aims to completely melt the metal powder and metallurgically combine with the surface of the part to be cladded, and the molybdenum wire is not completely melted; Step five: post-processing, according to the use requirement of the coating, the molybdenum wire fiber reinforced metal coating is heat treated or machined.

2. The method according to claim 1, wherein the method is characterized by, In step one, 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, and then dried; the metal powder is mixed and dried.

3. The method according to claim 2, wherein the method is a laser cladding method using waste molybdenum wire fiber reinforced metal coating. The cleaning method of the waste molybdenum wire in step one includes at least one of alkali washing, ultrasonic cleaning and electrolytic cleaning.

4. The method according to claim 1, wherein the method is characterized by, In step two, the thickness of the preform is 1-2mm, and the length and width dimensions of the preform are equivalent to those of the required coating.

5. The method according to claim 1, wherein the method is characterized by the steps of: In step two, the molybdenum wire fiber network structure is a regular ordered periodic distribution of molybdenum mesh after weaving or a random orientation of disordered fiber interwoven mesh.

6. The method according to claim 1, wherein the method is a laser cladding method using waste molybdenum wire fiber reinforced metal coating. In step three, before fixing the preform, the surface of the part to be cladded is 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.

7. The method according to claim 1, wherein the method is characterized by the steps of: In step four, when preform I is selected, synchronous powder feeding method is used for laser cladding, and the powder is the metal powder in step one; when preform II is selected, preposition method is used for laser cladding, and synchronous powder feeding is not required.

8. The method according to claim 1, wherein the method is a laser cladding method using waste molybdenum wire fiber reinforced metal coating. In step five, the heat treatment includes stress relief annealing and laser remelting, and the mechanical processing includes cutting, polishing, polishing and sand blasting.

9. A waste molybdenum wire fiber reinforced metal coating prepared by the method of any one of claims 1-8.

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