A method for preparing a wc / ni composite coating
WC/Ni composite coatings were prepared by high-energy ball milling and laser-directed energy deposition technology, which solved the problems of high hardness, high wear resistance and corrosion resistance of 316L stainless steel surface, and achieved tight bonding and performance improvement of the coating.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- KUNMING UNIV OF SCI & TECH
- Filing Date
- 2024-01-16
- Publication Date
- 2026-06-23
AI Technical Summary
Existing technologies struggle to produce high-hardness, high-wear-resistance, and corrosion-resistant WC/Ni composite coatings on 316L stainless steel surfaces, and traditional methods suffer from insufficient bonding strength and high dilution rates.
Spherical WC powder was prepared by high-energy ball milling, and WC/Ni coated powder was prepared by mixing soluble nickel salt, ammonium sulfate, triethanolamine, oxalic acid, fatty acid and ammonium polyacrylate. The coating was deposited on a 316L stainless steel substrate by laser directional energy deposition technology. The uniform distribution was achieved by controlling parameters such as laser power, scanning speed and powder feed rate.
A tightly bonded WC/Ni composite coating with low dilution rate was prepared, which significantly improved the hardness and wear resistance of the coating, while also enhancing its corrosion resistance. The coating hardness was approximately four times that of the substrate.
Smart Images
Figure CN117900470B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing a WC / Ni composite coating, belonging to the technical field of surface coating modification in additive manufacturing. Background Technology
[0002] Laser-directed energy deposition (LDED) is a highly flexible technology for preparing ceramic matrix composites. Initially applied only to the preparation of low-melting-point metals, its application has gradually expanded to near-net-shape forming of high-temperature refractory materials with continuous development and optimization of forming processes and equipment. This process utilizes a high-energy-density laser as a heat source to melt synchronously fed raw material powder, forming the composite material layer by layer. LDED offers greater flexibility in terms of component size, structure, and composition. Utilizing the additive manufacturing concept of "discrete + stacking," it achieves precise one-step forming of the workpiece through synchronous powder feeding. To improve workpiece performance, reinforcing particles can be doped into the raw material to prepare composite materials. Additive manufacturing technology features high design freedom, short product development cycles, and low manufacturing costs. It can rapidly manufacture complex ceramic parts without molds, showing broad application prospects in customizing high-performance, complex samples.
[0003] 316L stainless steel is increasingly being used in various fields. Wear is one of the main failure modes of metal parts; to reduce wear, a common method is to prepare a coating on the surface of the parts to improve their wear resistance; to improve the resistance of parts to seawater corrosion, while ensuring the mechanical properties of their surface and extending their service life, a corrosion-resistant alloy coating can be prepared on their surface. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing a WC / Ni composite coating. The prepared powder has the flowability and particle size required for high-throughput printing equipment, resulting in a WC / Ni composite coating with high hardness, high wear resistance, and corrosion resistance. The method specifically includes the following steps:
[0005] (1) Polish, clean and dry the stainless steel substrate.
[0006] (2) The final particle size of spherical WC powder was obtained by high-energy ball milling.
[0007] (3) Mix soluble nickel salt, ammonium sulfate, triethanolamine, oxalic acid, fatty acid, ammonium polyacrylate and water to obtain a mixed aqueous solution containing nickel. Adjust the pH of the mixed aqueous solution to alkaline by ammonia water, add WC powder of the final particle size obtained in step (2), add catalyst to react, ball mill after reaction, dry and sieve to obtain WC / Ni coated powder.
[0008] (4) Place the WC / Ni coated powder obtained in step (3) into the powder feeder of the 3D printing equipment, fix the stainless steel substrate processed in step (1) on the printing platform, establish a three-dimensional model, perform layer slicing, and in the protective gas Ar atmosphere, the powder delivered by the powder feeding nozzle reacts with the laser and melts onto the stainless steel substrate to obtain the WC / Ni composite coating.
[0009] Preferably, in step (1), the stainless steel substrate is 316L stainless steel with a size of 100*100*5mm; 180#, 400#, 800#, 1200#, and 2000# sandpaper are used for polishing; deionized water and anhydrous ethanol are used for cleaning, and the substrate is dried with a hair dryer and then placed in a vacuum drying oven for 12 hours.
[0010] Preferably, in step (2), the irregular or unevenly spherical WC powder is subjected to high-energy ball milling to achieve the final particle size. The final particle size of WC with good sphericity and uniform particle size is obtained mainly by high-speed (300r / min) and long-term (12h) forward and reverse ball milling.
[0011] Preferably, the WC powder obtained in step (2) has a particle size of 50 to 100 μm.
[0012] Preferably, in step (3), the soluble nickel salt is nickel sulfate; the amount of soluble nickel salt added in water is 100-200 g / L, the amount of ammonium sulfate added is 150-200 g / L, the amount of triethanolamine and oxalic acid added is 10-20 g / L, the amount of fatty acid added is 5-10 g / L, the amount of ammonium polyacrylate added is 5-10 g / L, and the amount of WC powder added is 100 g / L.
[0013] Preferably, the catalyst in step (3) is composed of nickel powder and palladium chloride, wherein the mass ratio of nickel powder to palladium chloride is 10000:4 to 10000:1, and the amount of catalyst used is 100g / L.
[0014] Preferably, palladium chloride in the catalyst can be replaced by anthraquinone and its derivatives.
[0015] Preferably, in step (3), the ball milling process uses a stainless steel ball mill jar, zirconium oxide beads as grinding balls, a ball-to-material ratio of 5:1, a rotation speed of 150 r / min, alcohol as the grinding medium, and carbon powder and nickel powder. The amount of carbon powder added is 1-2 g / L, the amount of nickel powder added is 5-10 g / L, and the ball milling is carried out for 24 hours.
[0016] Preferably, the WC / Ni coated powder obtained in step (3) has a particle size of 100 to 300 mesh.
[0017] Preferably, the equipment used in step (4) is a high-throughput metal laser 3D printing equipment with a laser spot diameter of 1.6 mm, a laser power of 800-1200 W, a scanning speed of 600-1500 mm / min, a powder feeding amount of 18 g / min, and an Ar gas flow rate of 6.7 L / min.
[0018] Beneficial effects of the present invention
[0019] (1) The material described in this invention has a good macroscopic morphology, resulting in a coating with low dilution rate, low porosity and tight bonding.
[0020] (2) The present invention uses a coating powder to make the reinforcing phase WC evenly distributed, thereby increasing the strength and hardness of each part of the coating. Attached Figure Description
[0021] Figure 1 This is a SEM image of the coating obtained in Example 1.
[0022] Figure 2 The image shows the X-ray diffraction pattern of the coating obtained in Example 1. Detailed Implementation
[0023] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.
[0024] Example 1
[0025] A method for preparing a WC / Ni composite coating specifically includes the following steps:
[0026] (1) Polish the 100*100*5mm 316L stainless steel with 180#, 400#, 800#, 1200# and 2000# sandpaper; clean it with deionized water and anhydrous ethanol, dry it with a hair dryer and then put it into a vacuum drying oven to dry for 12 hours.
[0027] (2) The spherical WC was prepared into powder with a particle size of 50 μm by high-energy ball milling.
[0028] (3) Add nickel sulfate at 100 g / L, ammonium sulfate at 200 g / L, triethanolamine at 10 g / L, oxalic acid at 10 g / L, fatty acid at 5 g / L, ammonium polyacrylate at 5 g / L, WC powder obtained in step (2) at 100 g / L, and catalyst at 100 g / L. The catalyst is composed of nickel powder and palladium chloride in a mass ratio of 10000:4 and a dosage of 100 g / L. The mixture is then subjected to a reduction reaction in H2 at a hydrogen pressure of 20 atm, a temperature of 200°C, and a reaction time of 20 min. After the reaction, ball milling is performed using a stainless steel ball mill jar with zirconia beads as grinding balls at a ball-to-material ratio of 5:1 and a rotation speed of 150 r / min. Alcohol is added as the grinding medium, carbon powder at 1 g / L, and nickel powder at 5 g / L. The mixture is ball milled for 24 h to obtain WC / Ni coated powder with a particle size of 100 mesh.
[0029] (4) Place the WC / Ni coated powder obtained in step (3) into the powder feeder of the 3D printing equipment, fix the stainless steel substrate processed in step (1) on the printing platform, establish a three-dimensional model, perform layer slicing, spray in an Ar atmosphere with a flow rate of 6.7L / min, with a laser spot diameter of 1.6mm, a laser power of 800w, a scanning speed of 900mm / min, and a powder feeding amount of 18g / min, to obtain a WC / Ni composite coating.
[0030] The WC / Ni composite coating obtained in Example 1 was observed using a scanning electron microscope, and the results are as follows: Figure 1 As shown, from Figure 1 As can be seen, the lower part is the substrate, and the upper part is the coating. The bright part of the coating is WC, and the gray part is the binder metal Ni. It can be seen that the WC structure is evenly distributed, which uniformly enhances the hardness and strength of all parts of the coating.
[0031] The WC / Ni composite coating obtained in Example 1 was subjected to X-ray diffraction, and the results are as follows: Figure 2 As shown in the figure, some WC particles decompose under the influence of a strong laser. They then combine with alloying elements in the molten pool to form WC, W2C, Cr5B3, and Cr. 23 A series of complex phases including C6, FeNi3, and γ(N, F).
[0032] The WC / Ni composite coating obtained in Example 1 was subjected to Vickers hardness testing, and the Vickers hardness of the coating portion was found to be above 1000 HV, which is about 4 times that of the substrate.
[0033] Example 2
[0034] (1) Polish the 100*100*5mm 316L stainless steel with 180#, 400#, 800#, 1200# and 2000# sandpaper; clean it with deionized water and anhydrous ethanol, dry it with a hair dryer and then put it into a vacuum drying oven to dry for 12 hours.
[0035] (2) The spherical WC was prepared into powder with a particle size of 100 μm by high-energy ball milling.
[0036] (3) Add nickel sulfate at 100 g / L, ammonium sulfate at 150 g / L, triethanolamine at 20 g / L, oxalic acid at 20 g / L, fatty acid at 5 g / L, ammonium polyacrylate at 5 g / L, WC powder obtained in step (2) at 100 g / L, and catalyst at 100 g / L. The catalyst is composed of nickel powder and palladium chloride in a mass ratio of 10000:4, and the amount of catalyst used is 100 g / L. The mixture was then subjected to a reduction reaction in H2 at a hydrogen pressure of 30 atm and a temperature of 120°C for 30 min. After the reaction, the mixture was ball-milled in a stainless steel ball mill jar with zirconia beads as grinding balls at a ball-to-material ratio of 5:1 and a rotation speed of 100 r / min. Alcohol was added as the grinding medium, and carbon powder was added at 1 g / L and nickel powder at 5 g / L. The mixture was ball-milled for 24 h to obtain WC / Ni coated powder with a particle size of 300 mesh.
[0037] (4) Place the WC / Ni coated powder obtained in step (3) into the powder feeder of the 3D printing equipment, fix the stainless steel substrate processed in step (1) on the printing platform, establish a three-dimensional model, perform layer slicing, spray in an Ar atmosphere with a flow rate of 6.7L / min, with a laser spot diameter of 1.6mm, a laser power of 800w, a scanning speed of 1500mm / min, and a powder feeding amount of 18g / min to obtain a WC / Ni composite coating.
[0038] Example 3
[0039] (1) Polish the 100*100*5mm 316L stainless steel with 180#, 400#, 800#, 1200# and 2000# sandpaper; clean it with deionized water and anhydrous ethanol, dry it with a hair dryer and then put it into a vacuum drying oven to dry for 12 hours.
[0040] (2) The spherical WC was prepared into powder with a particle size of 50 μm by high-energy ball milling.
[0041] (3) Add nickel sulfate at 200 g / L, ammonium sulfate at 200 g / L, triethanolamine at 10 g / L, oxalic acid at 10 g / L, fatty acid at 10 g / L, ammonium polyacrylate at 10 g / L, WC powder obtained in step (2) at 100 g / L, and catalyst at 100 g / L. The catalyst is composed of nickel powder and anthraquinone in a mass ratio of 10000:1. A mixture is obtained and the mixture is reduced in H2 at a hydrogen pressure of 20 atm, a temperature of 200°C, and a reaction time of 20 min. After the reaction, ball milling is performed. The ball milling process uses a stainless steel ball mill jar, zirconium oxide beads as grinding balls, a ball-to-material ratio of 5:1, a rotation speed of 100 r / min, alcohol as the grinding medium, carbon powder at 1 g / L, and nickel powder at 5 g / L. The ball milling is performed for 24 h to obtain WC / Ni coated powder with a particle size of 100 mesh.
[0042] (4) Place the WC / Ni coated powder obtained in step (3) into the powder feeder of the 3D printing equipment, fix the stainless steel substrate processed in step (1) on the printing platform, establish a three-dimensional model, perform layer slicing, spray in an Ar atmosphere with a flow rate of 6.7L / min, with a laser spot diameter of 1.6mm, a laser power of 1200w, a scanning speed of 600mm / min, and a powder feeding amount of 18g / min to obtain a WC / Ni composite coating.
[0043] The coatings of Examples 2 and 3 were tested using the same method as in Example 1. It can be seen that the morphology of the cladding layer is similar to that of Example 1, with no obvious defects such as cracks and pores. Analysis of the X-ray diffraction pattern of the cladding layer shows that the main components in the coating are WC, W2C, FeNi3, etc.
Claims
1. A method for preparing a WC / Ni composite coating, characterized in that: Specifically, the steps include the following: (1) Polish, clean and dry the stainless steel substrate; (2) The final particle size of spherical WC powder was obtained by high-energy ball milling; (3) Mix soluble nickel salt, ammonium sulfate, triethanolamine, oxalic acid, fatty acid, ammonium polyacrylate and water to obtain a mixed aqueous solution containing nickel. Adjust the pH of the mixed aqueous solution to alkaline by ammonia water, add WC powder of the final particle size obtained in step (2), add catalyst to react, and after the reaction is completed, ball mill, dry and sieve to obtain WC / Ni coated powder. (4) Place the WC / Ni coated powder obtained in step (3) into the powder feeder of the 3D printing equipment, fix the stainless steel substrate processed in step (1) on the printing platform, establish a three-dimensional model, perform layer slicing, and in the protective gas Ar atmosphere, the powder sent by the powder feeding nozzle reacts with the laser and melts onto the stainless steel substrate to obtain the WC / Ni composite coating. The WC powder obtained in step (2) has a particle size of 50~100μm; In step (3), the soluble nickel salt is nickel sulfate; the amount of soluble nickel salt added to water is 100-200 g / L, the amount of ammonium sulfate added is 150-200 g / L, the amount of triethanolamine and oxalic acid added is 10-20 g / L, the amount of fatty acid added is 5-10 g / L, the amount of ammonium polyacrylate added is 5-10 g / L, and the amount of WC powder added is 100 g / L. In step (3), the catalyst is composed of nickel powder and palladium chloride, wherein the mass ratio of nickel powder to palladium chloride is 10000:4~10000:1, and the amount of catalyst is 100g / L; the reaction conditions are that the hydrogen pressure of the H2 reduction reaction is 20~30atm, the temperature is 120~200℃, and the reaction time is 20~30min. In step (3), the ball milling process uses a stainless steel ball milling jar, zirconium oxide beads as grinding balls, a ball-to-material ratio of 5:1, a rotation speed of 150 r / min, alcohol as the grinding medium, and carbon powder and nickel powder. The amount of carbon powder added is 1 g / L, and the amount of nickel powder added is 5 g / L. The ball milling is carried out for 24 hours. In step (3), the particle size of the WC / Ni coated powder obtained is 100~300 mesh; The equipment used in step (4) is a high-throughput metal laser 3D printing equipment with a laser spot diameter of 1.6 mm, a laser power of 800~1200w, a scanning speed of 600~1500mm / min, a powder feeding amount of 18g / min, and an Ar gas flow rate of 6.7L / min.
2. The method for preparing the WC / Ni composite coating according to claim 1, characterized in that: In step (1), the stainless steel substrate is 316L stainless steel; 180#, 400#, 800#, 1200#, and 2000# sandpaper are used for polishing; deionized water and anhydrous ethanol are used for cleaning, and the substrate is dried with a hair dryer and then placed in a vacuum drying oven for 12 hours.
3. The method for preparing the WC / Ni composite coating according to claim 1, characterized in that: Step (2) The final particle size WC with good sphericity and uniform particle size is obtained by ball milling at a high speed of 300r / min for 12 hours in both forward and reverse directions.
4. The method for preparing the WC / Ni composite coating according to claim 1, characterized in that: Palladium chloride in the catalyst can be replaced by anthraquinone and its derivatives.