Preparation method of chemical composite plating solution based on nano niobium carbide

Abstract

The invention discloses a preparation method of a chemical composite plating solution based on nano niobium carbide. The preparation method comprises the following steps: step 1, pretreating niobium carbide (NbC) powder; step 2, preparing a chemical plating solution, wherein every 1L of the chemical plating solution contains 30g of nickel chloride, 20g of sodium hypophosphite, 10g of sodium citrate, 5g of glycine, 10g of sodium acetate, 0.3 g of sodium dodecyl benzene sulfonate and 80mg of zinc molybdate; fixing the volume to 1L by using distilled water; 3, measuring the niobium carbide suspension liquid, mixing the niobium carbide suspension liquid with the chemical plating solution, and fixing the volume, so that the content of niobium carbide in the chemical composite plating solution is 0.01-0.3 g / L; adjusting the pH value of the solution to 5.8; according to the method, niobium carbide nanoparticles are added into the chemical composite plating solution, so that the surface of a plated part and metal gold are combined with the particles, and the hardness and wear resistance of a base material are effectively improved; the effect on a 60-80-micron nickel-phosphorus coating in the industry is achieved through the ultrathin chemical composite coating (8-10 microns), so that the corrosion resistance and the wear resistance of the product are enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of material surface engineering, and particularly relates to a preparation method of a chemical composite plating solution based on niobium carbide nanoparticles. Background Art

[0002] Although traditional electroplating and electroless plating can provide good anti-corrosion protection and decorative effects, in some applications, they have deficiencies in aspects such as wear resistance, hardness, and high-temperature resistance. To overcome these limitations, researchers have begun to explore how to add microparticles or nanoparticles with special properties to the coating to improve the overall performance of the coating.

[0003] Chemical composite plating technology is an advanced surface engineering technology developed on the basis of traditional electroplating and electroless plating. It utilizes the latest achievements of modern materials science, combines industrial demands and environmental protection requirements, and provides new solutions for the application of various high-performance materials. Chemical composite plating is an advanced surface treatment technology that enhances the performance of the coating by introducing non-metallic particles (such as carbides, oxides, graphene, etc.) into the traditional chemical coating. In the fields of aerospace, automotive manufacturing, electronics industry, tool manufacturing, etc., the requirements for material performance are getting higher and higher, especially for use environments under extreme conditions, such as high temperature, high pressure, corrosive media, etc.

[0004] Patent Application No.: CN201910755136.6 discloses a preparation method for a corrosion-resistant structure of a petroleum stainless steel pipeline. This method proposes a method for preparing a coating with hydrophobicity and corrosion resistance. By means of technical measures such as pre-treating the stainless steel surface, performing micro-nano double roughness structure and low surface energy modification, the quality and durability of the coating can be improved. It uses the method of electroless nickel plating, and through multiple electroless plating processes, a corrosion-resistant coating layer with a certain thickness is formed on the substrate surface. The formed coating layer has poor wear resistance and fatigue strength. Usually, in order to improve the wear resistance of its surface, the method of increasing the number of electroplating times and thickening the coating layer thickness is adopted to form a thicker coating layer to improve the wear resistance. This makes the production process flow longer, and the coating layer on the surface of the produced coating product is thicker; the coating uniformity is not good, and as the coating layer thickness increases, it becomes more difficult to maintain the coating uniformity, and uneven thickness may occur in some areas; in addition, the subsequent coating layer may become relatively brittle and hard, reducing the fatigue strength and toughness of the material; and due to the increase in the coating layer thickness, the overall weight of the material also increases significantly. For some weight-sensitive application fields, such as aerospace components, the thicker coating layer increases the overall weight and affects the design requirements.

[0005] In view of the above, it is necessary to propose a preparation method of a chemical composite plating solution based on niobium carbide nanoparticles to solve the above problems. Summary of the Invention

[0006] The object of the present invention is to overcome the defects existing in the prior art and provide a preparation method of a chemical composite plating solution based on niobium carbide nanoparticles. By introducing insoluble second-phase inorganic nanoparticles - niobium carbide into the plating solution as an additive for cemented carbide, NbC can significantly improve the hot hardness, thermal shock resistance, hot pressing resistance, and oxidation resistance of cemented carbide. Cutting tools made of NbC-reinforced cemented carbide also have good properties such as hot hardness, thermal shock resistance, and thermal oxidation resistance.

[0007] To achieve the above object, the technical solution of the present invention is as follows: A preparation method of a chemical composite plating solution based on niobium carbide nanoparticles, including a substrate material, a pre-plating layer, and a composite plating layer. The composite plating layer adheres to the surface of the pre-plating layer, and the pre-plating layer adheres to the surface of the substrate material. The substrate material can be a metal or a non-metal. Metals include but are not limited to Q235B carbon steel, copper alloy, aluminum alloy, nickel material, and stainless steel. Non-metal materials include but are not limited to plastics, ceramics, glass, and neodymium iron boron. The pre-plating layer is a nickel layer, and the thickness of the composite plating layer is 8 - 10 μm, as Figure 4 shown.

[0008] For the preparation of the pre-plating layer, taking the nickel layer as the substrate can make the subsequent plating layer adhere better and improve the adhesion of the plating layer. The nickel layer itself also has good corrosion resistance, equivalent to a double-layer corrosion-resistant layer. The composition of the pre-plating nickel solution includes: nickel chloride hexahydrate (NiCl2•6H2O) 40 - 50 g / L, nickel sulfate hexahydrate (NiSO4•6H2O) 240 - 260 g / L, boric acid (H3BO3) 25 - 35 g / L, sodium dodecyl sulfate 0.20 - 0.30 g / L, sodium hydroxymethylsulfonate (PN) 35 - 45 mg / L, and propynol propoxy ether (PAP) 25 - 35 mg / L; The process conditions for the pre-plating layer are: the anode is a nickel plate, taking Q235B as the substrate material for the cathode, the temperature is 20 - 30 °C, the pH is 3 - 4, the plating time is 1 - 2 min, and the current density during plating is 2 - 3 A / dm 2 .

[0009] Nickel ions mainly come from nickel sulfate hexahydrate and partially from nickel chloride. Nickel chloride has two main functions: one is to greatly improve the conductivity of the solution and reduce the required voltage; the other is very important for obtaining satisfactory dissolution of the nickel anode. Boric acid is a buffer, and its main function is to control the pH value of the solution. Sodium dodecyl sulfate is a plating solution additive that reduces the surface tension of the solution and promotes the release of bubbles, improves the uniformity and smoothness of the plating layer, and reduces uneven deposition. Sodium hydroxymethylsulfonate (PN) and propynol propoxy ether (PAP) can significantly change the appearance and properties as the "carrier" and "brightener" of bright pre-electroplating, making the plating layer brighter and flatter.

[0010] A composite coating can be formed on the surface of the pre - coating using electroless plating solution or electroless composite plating solution, as Figure 1 shown.

[0011] As an implementation method, the first coating is the pre - coating, and the second coating is the electroless coating. The composition of the electroless plating solution used for the electroless coating includes: main salt NiCl₂•6H₂O 225 - 35 g / L, reducing agent sodium hypophosphite (NaH₂PO₂•H₂O) 15 - 25 g / L, main complexing agent sodium citrate (Na₃C₆H₅O₇•2H₂O) 8 - 12 g / L, auxiliary complexing agent glycine [CH₂(NH₂)COOH] 4 - 6 g / L, buffer sodium acetate (CH₃COONa) 8 - 12 g / L, surfactant sodium dodecylbenzenesulfonate 0.25 - 0.35 g / L, stabilizer zinc molybdate 75 - 85 mg / L; the temperature is 80 - 85 °C, the pH is 5 - 6, and the plating time is 0.5 - 1.5 h; sodium citrate is used as the main complexing agent, which has strong complexing ability and the plating solution is very stable, but the plating rate is low. In this patent, a second complexing agent, glycine, is used. The complexing ability of glycine is relatively weak and it is generally not used alone as a complexing agent, but mainly added to the plating solution as an auxiliary complexing agent. Its function is that by adding a small amount of glycine, the deposition rate can be significantly increased and the surface quality of the deposited layer can be improved.

[0012] The specific steps for preparing the electroless plating solution are as follows: 1) Based on 1000 mL of plating solution as the conversion basis, successively weigh the main salt, reducing agent, complexing agent, surfactant, and stabilizer according to the concentration ratio and dissolve them separately with a small amount of distilled water. If the chemical solution is not prone to deterioration, it can be prepared into a mother liquor in advance for easy use in future experiments; 2) Slowly pour the completely dissolved main salt solution into the uniformly mixed complexing agent solution in sequence; 3) Slowly pour the measured reducing agent solution into the solution prepared in step 2); 4) Pour the stabilizer solution, buffer solution and other additives into the solution prepared in step 3) respectively; 5) Dilute the above - mentioned mixed solution with distilled water to be close to 1000 mL, and adjust the pH value with the solution of AMP - 95 (Dow Chemical, USA) and ammonia water.

[0013] 6) Make up the volume, dilute with distilled water until the specified volume (1000 mL). At the same time, correct and adjust the pH value again.

[0014] As another embodiment, nickel pre - plating is also used as the first coating, and the second coating is formed by electroless composite plating. In this embodiment, insoluble particles are added to the electroless composite plating solution. When the coating is formed, the insoluble particles are co - deposited on the nickel - phosphorus alloy. The co - deposition of alloy second - phase particles and different substances in the coating produces a new generation of electroless composite coating to produce coatings with different physical and chemical properties. The specific steps are as follows: NbC (niobium carbide) powder pretreatment: The purchased raw material of NbC powder has a purity of 99.9%, and the NbC powder has a Fisher average particle size of less than 3μm.

[0015] The NbC powder is wet - milled and mixed evenly by the rolling ball - milling method and then dried to obtain nano - niobium carbide powder. In the present invention, the average particle size of the ultrafine NbC powder is 100nm through the pretreatment of NbC powder. As Figure 2 shown, the niobium carbide is refined to the nanoscale. The more uniform its distribution in the crystal grains, the more beneficial it is to improve the strength of the coating. In the present invention, wet - milling is used to make the ultrafine NbC powder more fully and evenly distributed, solving the problem that it is difficult to evenly mix the nearly ultrafine NbC powder, improving the uniformity of the distribution of the NbC second - phase in the crystal grains, and further enhancing the strengthening effect of NbC.

[0016] The NbC powder raw material is subjected to high - energy wet - milling ball - milling in a ball - mill under the condition that the rotation speed is above 1000r / min. The above - mentioned high - energy ball - milling further refines the particle size of the NbC powder and promotes the uniform mixing of the NbC powder in the subsequent electroless composite plating solution.

[0017] Specifically, the NbC powder raw material is dispersed in absolute ethanol and stirred, and then the solution is poured into a ball - mill tank filled with nitrogen. To ensure the ball - milling efficiency, grinding balls with a mass ratio of 10:1 to the material are weighed into the ball - mill tank. The tank is placed in a ball - mill for ball - milling for 48 hours, and then the mixture is drained and placed in a vacuum drying oven for drying. After drying and screening, NbC powder with uniform particle size is obtained, and the average particle size of the NbC powder is 100nm. After the NbC powder is stirred evenly with water, an HF solution is added to the suspension. Hydrofluoric acid is used. On the one hand, due to the strong corrosiveness of HF, it is used to clean the NbC powder to remove pollutants that are difficult to remove by other means. On the other hand, it can be used as a surfactant or dispersant, which helps to improve the interaction force between NbC powder particles, thereby improving the dispersibility and stability of the powder in the solvent. This is mainly achieved by changing the surface properties of the particles. Then it is left standing for more than 24h; next, the suspension is centrifuged; the NbC obtained by centrifugation is added to deionized water, and ultrasonic stirring is used to obtain a uniform suspension for subsequent use.

[0018] The preparation method of the electroless composite plating solution includes the following steps: Step 1: Based on the aforementioned electroless plating solution, measure an appropriate amount of the electroless plating solution. Step 2: Measure a niobium carbide suspension, add a surfactant (cetyltrimethylammonium bromide (CTAB)) thereto, and a 5% Nafion (0.5 mL) solution, and stir evenly. Step 3: Ultrasonically stir the niobium carbide suspension in Step 2 for 10 min to fully wet the particles. Step 4: Mix the niobium carbide suspension processed in Step 3 with the electroless plating solution in Step 1, then stir evenly, then dilute and make up the volume, and adjust the pH to 5.8 to form an electroless composite plating solution. Step 5: Ultrasonically stir the electroless composite plating solution for 30 min.

[0019] Cetyltrimethylammonium bromide is added to the niobium carbide (NbC) suspension. CTAB is a cationic surfactant that can improve the stability and dispersibility of the niobium carbide suspension. CTAB can adsorb on the surface of niobium carbide particles to form a protective film on the surface. By electrostatic repulsion or steric hindrance effects, the agglomeration phenomenon between particles can be reduced, thereby improving the dispersion degree of the particles in the solvent. To prevent the agglomeration of NbC particles, CTAB can change the surface charge properties of the particles, which helps prevent the particles from settling due to gravity, making the suspension more stable. Thus, the stability of the suspension is improved. CTAB can change the properties of the substrate surface, making it more receptive to the deposition of metal ions, thereby improving the quality of the coating.

[0020] Nafion is a perfluorosulfonic acid / perfluorocarboxylic acid copolymer, which has excellent proton conduction performance, chemical stability, and mechanical strength; adding a 5% Nafion solution to the niobium carbide (NbC) suspension can improve the dispersion. As a dispersant, it helps the metal ions to be more evenly distributed in the solution, thereby helping to obtain a more uniform and dense coating. In Step 2, the addition of CTAB has already helped to improve the dispersion of niobium carbide particles, but the introduction of Nafion can further help to maintain a stable suspension state, especially under long-term storage or specific processing conditions. It can also adjust the hydrophilic-hydrophobic balance: Nafion itself has a certain hydrophilicity, which will affect the wetting characteristics of the final material surface, which is beneficial for application scenarios where the liquid contact angle needs to be controlled on the surface of electroless composite plating products. In addition, Nafion can be used to adjust the pH value. Nafion has a certain acidity, which can help to adjust the pH value of the electroless plating solution and maintain suitable reaction conditions.

[0021] The combined use of Nafion, CTAB, and niobium carbide can produce a synergistic effect, making the coating not only have good electrical conductivity and mechanical properties, but also excellent corrosion resistance and adhesion. By precisely controlling the proportions of the components and the treatment conditions, the properties such as the thickness, density, and porosity of the coating can be customized to meet the requirements of different applications. Good dispersibility and uniformity can improve the efficiency of the electroless plating process, reduce defects, and improve product quality.

[0022] The key technologies for adding nanoparticle NbC to form a smooth and flat coating in the composite electroless plating solution mainly include the following aspects: 1. Uniform dispersion of nanoparticles: Due to their high surface energy, nano NbC particles are extremely prone to agglomeration in the plating solution, affecting the uniformity and flatness of the coating. Therefore, ensuring the uniform dispersion of nanoparticles in the plating solution is the key. In this invention, physical methods such as mechanical stirring and ultrasonic dispersion, as well as adding surfactants, are used to achieve the uniform dispersion of nanoparticles.

[0023] 2. Use of surfactants: The type and concentration of surfactants have an important impact on the adsorption amount and distribution uniformity of nanoparticles. Ionic surfactants and non-ionic surfactants can prevent the agglomeration of nanoparticles by forming an electric double layer or hydration, improving the stability of the plating solution.

[0024] 3. Plating solution composition and ratio: Select appropriate coating materials and precisely control the ratio of the materials to obtain the desired nano-coating properties and characteristics. The concentration of nanoparticles in the plating solution and the other chemical components of the plating solution need to be precisely proportioned to ensure the uniformity and flatness of the coating.

[0025] After preparing the composite electroless plating solution and pretreating and pre-plating nickel on the specimen, the plating process is as follows: 1) Put the prepared plating solution into a thermostatic heating magnetic stirrer and heat it to 82 °C.

[0026] 2) Put the specimen after pre-plating nickel into the composite electroless plating solution, adjust the rotation speed to 300 r / min, and carry out plating.

[0027] 3) After plating for 60 min, take out the specimen, rinse it with deionized water, and then put it into absolute ethanol and place it in an ultrasonic cleaner for ultrasonic cleaning for 10 min. 4) Take it out after cleaning and dry it in a blast drying oven.

[0028] The comparison between the surface layer formed by the chemical composite plating method of the present invention and the surface layer formed by the non-chemical composite plating method is as Figure 3 shown.

[0029] Chemical composite electroless nickel plating is a process in which insoluble particles are added to an electroless nickel plating solution and co-deposited on a nickel-phosphorus alloy to produce different coatings with different physical and chemical properties. The co-deposition of alloy second-phase particles and different substances in the coating produces a new generation of chemical composite coatings. Previous studies have shown that some composite coatings have excellent wear resistance and corrosion resistance.

[0030] During the plating process, the second-phase particles are jointly affected by three forces: gravity, van der Waals force, and Coulomb force. The deposition process of the composite coating can be divided into two stages: weak adsorption and strong adsorption.

[0031] a) Weak adsorption process: Due to the influence of the van der Waals force, the second-phase particles formed by carrying ions and solvent molecules will be adsorbed on the surface of the metal to be plated. There is a relatively balanced state between these adsorbed second-phase particles and the second-phase particles suspended in the plating solution.

[0032] b) In the first step of the strong adsorption process, the second-phase particles in the weak adsorption state directly contact the surface of the metal to be plated due to the action of the Coulomb force, forming electrochemical adsorption, that is, the strong adsorption state. During the co-deposition of nickel and phosphorus, these strongly adsorbed second-phase particles will be wrapped and embedded in the alloy coating.

[0033] On the one hand, the electroless nickel-phosphorus coating has unprecedented properties, unique corrosion resistance and wear resistance. On the other hand, with the continuous in-depth research of nanomaterials and nanotechnology, in the present invention, nanoscale insoluble particles niobium carbide are introduced into the composite coating. The chemical composite coating is prepared by chemically depositing nanometer particles and attaching them to the substrate surface to form nanomaterials, endowing the substrate with special properties. The chemical composite coating technology with added nanoparticles in the present invention has the advantages of simple equipment, convenient operation, low cost, easy operation, etc., and can improve the corrosion resistance, wear resistance and oxidation resistance of the metal surface, and endow the material with special properties such as a decorative appearance.

[0034] By adding insoluble second-phase particles - niobium carbide (NbC) to the plating solution and uniformly compounding it in the matrix metal, a composite coating with diverse physical and chemical properties is formed. On the basis of maintaining the performance of the original matrix metal coating and combining the characteristics of the composite phase, not only the performance of the metal coating is enhanced, but also the original coating is modified. By adjusting the combination of the matrix metal and the dispersed particles, a variety of chemical composite coatings with excellent properties can be obtained, and these properties include high hardness, high wear resistance, self-lubrication, high heat resistance, corrosion resistance, and special decoration, etc.

[0035] The nanometer niobium carbide particles are distributed in the matrix metal in a discrete manner, constituting a discontinuous phase. The chemical composite plating can utilize the combination of different matrix metals and dispersed phases to realize the preparation of a variety of chemical composite coatings with excellent properties.

[0036] Improve wear resistance: In the chemical composite coating Ni-P / NbC of this patent, the addition of hard particles (niobium carbide nanoparticles) can be dispersed in the coating matrix (Ni-P alloy). These hard particles can effectively refine the matrix metal, thereby increasing the hardness of the matrix metal. This dispersion strengthening mechanism can significantly improve the wear resistance of the coating. During the wear process, the niobium carbide hard phase particles play a supporting role due to their high hardness, excellent wear resistance, large yield limit and compressive capacity, and become the first sliding surface. The matrix metal Ni-P alloy is then coated around the hard particles to form the second sliding surface. Based on the double protection, therefore, the hard particle chemical composite coating has excellent wear resistance characteristics. In addition, as Figure 4 shown, compared with the Ni-P coating and carbon steel substrate, the connection between the Ni-P / NbC coating of the composite coating and carbon steel is tight, without obvious gaps, indicating stronger adhesion.

[0037] Improve hardness: The hardness of the chemical composite coating Ni-P / NbC is significantly enhanced. This is mainly due to the introduction of hard nanoparticles NbC. The presence of these particles increases the hardness of the coating, thereby enhancing its wear resistance.

[0038] The Vickers hardness (HV) value of Q235B steel is about 130 - 150, the Vickers hardness value of the electroless Ni-P alloy coating is about 740 - 760, and the Vickers hardness value of the chemical composite coating Ni-P / NbC is about 980 - 1000.

[0039] Improve corrosion resistance: Compared with the Ni-P alloy coating, the chemical composite coating Ni-P / NbC has enhanced corrosion resistance, far higher than that of the matrix carbon steel. This is because the added nanoparticles in the composite coating can form a denser structure, reducing the penetration of corrosive media, thereby improving the corrosion resistance. The improvement of corrosion resistance can be reflected by the improvement of electrochemical properties. In the electrochemical test, the chemical composite coating Ni-P / NbC shows more excellent corrosion resistance compared with the Ni-P alloy coating. The reason for this phenomenon is the presence of nanoparticles in the composite coating, which improves the electrochemical properties, reduces the corrosion current, and increases the self-corrosion potential, thereby enhancing its corrosion resistance.

[0040] For usage scenarios with high requirements for conductivity, the addition of niobium carbide will also increase the conductivity of the coating: (1) Concentration of nickel chloride: The concentration of nickel chloride has a significant impact on the deposition rate, deposition amount and electrical conductivity of the amorphous coating. As the concentration of nickel salt increases, the deposition rate and deposition amount gradually increase, while the sheet resistance of the coating gradually decreases and the electrical conductivity increases. In the plating solution of this patent, when the concentration of nickel sulfate is 30 g / L, it has good electrical conductivity.

[0041] (2) Electroless plating time: The extension of the electroless plating time will affect the resistance value of the conductive coating. With the increase of the electroless plating time, the resistance value of the aromatic coating at the same length gradually decreases, and the decreasing amplitude gradually decreases with the extension of time and finally tends to be stable. When the electroless plating time is 20 minutes, the coating is basically perfect. After that, when the time is extended, the thickness of the coating continues to increase, but the increase in thickness at this time will not cause obvious changes in its conductivity.

[0042] (3) Microstructure: This ultrafine microstructure on the surface of the chemical composite coating Ni-P / NbC enables the alloy to have the best comprehensive performance of tensile strength and conductivity.

[0043] (4) Pre-plating nickel time: The pre-plating nickel time affects the corrosion resistance and porosity of the electroless Ni-P alloy coating, and thus affects the conductivity. With the extension of the pre-plating Ni time, the porosity of the Ni-P alloy coating shows a trend of first decreasing and then increasing. In this patent, when the pre-plating Ni time is 1-2 minutes, the corrosion resistance is the best at this time.

[0044] (5) Doping the second phase: Introducing NbC particles into the Ni-P alloy can induce the redistribution of electron density, optimize the adsorption energy of intermediate products, and reduce the energy barrier, thereby improving the conductivity.

[0045] The advantages and beneficial effects of the present invention are as follows: 1. By adding niobium carbide, this second-phase inorganic nanoparticle, to the chemical composite plating solution in the present invention, the surface of the workpiece and the metal matrix are combined with the particles, and thus a composite coating of the material can be obtained, effectively improving the hardness and wear resistance of the substrate. Moreover, this method can replace multiple coatings in the prior art through one-time chemical composite plating, so that the effect achieved by a 60-80 μm nickel-phosphorus coating in the industry can be achieved through an ultra-thin chemical composite coating (8-10 μm). The introduction of NBC nanoparticles enhances the adhesion between the coating and the substrate, and improves the corrosion resistance and wear resistance of the product.

[0046] 2. The advantages of the present invention are that the process equipment is simple and the operation is simple. The dispersion force of the plating solution for the chemical composite plating of the present invention is close to 100%, without obvious edge effect, and can replicate the shape of the substrate (workpiece), especially suitable for surface plating (coating uniformity) of complex-shaped workpieces, cavity parts, deep-hole parts, inner walls of pipe fittings, etc. Metallization of non-metal surfaces: Through pretreatment such as sensitization and activation, electroless plating can be carried out on the surfaces of non-metals (non-conductors) such as plastics, glass, ceramics, and semiconductor materials, while electroplating can only be carried out on the surface of conductors. Brief Description of the Drawings

[0047] Figure 1 is a schematic flow chart of a preparation method of a chemical composite plating solution based on niobium carbide nanoparticles of the present invention; Figure 2It is the SEM image of the pretreated NbC nanoparticles in the present invention; Figure 3 It is the SEM image of the Ni-P coating (left) and the Ni-P / NbC composite coating (right); Figure 4 It is the cross-sectional SEM image of the Ni-P coating (left) and the Ni-P / NbC composite coating (right); Specific embodiments

[0048] The following combines the drawings and examples to further describe the specific embodiments of the present invention. The following examples are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0049] A preparation method of a chemical composite plating solution based on niobium carbide nanoparticles includes the following steps: Step 1, pretreat the niobium carbide NbC powder. The purchased niobium carbide NbC powder has a purity of 99.9%. Disperse 1 g of NbC powder in 100 mL of absolute ethanol and stir for 20 min, then pour the solution into a ball milling tank filled with nitrogen; add grinding balls to ensure the ball milling efficiency, and ball mill for 48 hours, then drain the mixture and place it in a vacuum drying oven to dry at 120 °C for 16 hours. After drying and screening, NbC powder with uniform particle size is obtained. After the NbC powder is stirred evenly with water, add HF solution to the suspension and let it stand for more than 24 h; then perform centrifugal separation on the suspension; the centrifuged NbC is added to deionized water and stirred ultrasonically to obtain a uniform suspension. The prepared mother liquor concentration of the NbC suspension is: 1 g / L, and the average particle size of NbC is 100 nm, for experimental measurement. Based on production, a batch of niobium carbide nano-powders can be processed at one time to prepare the suspension.

[0050] Step 2, prepare the electroless plating solution, and its components include: nickel chloride, sodium hypophosphite, sodium citrate, glycine, sodium acetate, sodium dodecylbenzenesulfonate, zinc molybdate. Nickel chloride is the main salt, sodium hypophosphite is the reducing agent, sodium citrate is the main complexing agent, glycine is the auxiliary complexing agent, sodium acetate is the buffer, sodium dodecylbenzenesulfonate is the surfactant, and zinc molybdate is the stabilizer; Specifically, based on 1000 mL of the plating solution as the conversion basis, the preparation of the electroless plating solution includes the following steps: Step 21, successively weigh the main salt, reducing agent, complexing agent, surfactant, and stabilizer according to the concentration ratio and dissolve them separately with a small amount of distilled water; taking the preparation of 1000 mL of electroless plating solution as an example, weigh 30 g of the main salt, 20 g of the reducing agent, 10 g of the main complexing agent sodium citrate, 5 g of the auxiliary complexing agent glycine, 10 g of the buffer sodium acetate, 0.3 g of the surfactant, and 80 mg of the stabilizer; Step 22: Slowly pour the completely dissolved main salt solution into the uniformly mixed complexing agent solution in sequence. Step 23: Slowly pour the measured reducing agent solution into the solution prepared in Step 22. Step 24: Pour additives such as stabilizer solution and buffer solution into the solution prepared in Step 23 respectively. Step 25: Dilute the above mixed solution with distilled water to be close to 1000 ml, and adjust the pH value to 5.8 with the solution of AMP-95 (Dow Chemical, USA) and ammonia water. Step 26: Make up the volume, dilute it to the specified volume (1000 ml) with distilled water. At the same time, calibrate and adjust the pH value again.

[0051] Step 3: Measure the niobium carbide suspension described in Step 1, add a surfactant and Nafion solution and stir evenly; respectively measure 10, 30, 80, 100, 200, 300 mL of the niobium carbide suspension, then add a surfactant (100 mg cetyltrimethylammonium bromide (CTAB)), and a 5% Nafion (0.5 mL) solution and stir evenly. Step 4: Ultrasonically stir the niobium carbide suspension obtained in Step 3 for 10 min to fully wet the niobium carbide particles. Step 5: Mix the niobium carbide suspension in Step 4 with the electroless plating solution, then stir evenly, and then dilute and make up the volume to make the content of niobium carbide in the electroless composite plating solution be 0.01 - 0.3 g / L; adjust the pH of the solution to 5.8. Step 6: Ultrasonically stir the composite plating solution obtained in Step 5 to obtain electroless composite plating solutions with different niobium carbide contents.

[0052] Example 1: Measure 10 ml of the niobium carbide suspension, add 100 mg of CTAB as the surfactant, add 0.5 mL of 5% Nafion solution and stir evenly; mix it with the electroless plating solution and make up the volume to 1000 ml, adjust the pH to 5.8 to obtain an electroless composite plating solution with a niobium carbide content of 0.01 g / L.

[0053] Example 2: Measure 30 ml of the niobium carbide suspension, add 100 mg of CTAB as the surfactant, add 0.5 mL of 5% Nafion solution and stir evenly; mix it with the electroless plating solution and make up the volume to 1000 ml, adjust the pH to 5.8 to obtain an electroless composite plating solution with a niobium carbide content of 0.03 g / L.

[0054] Example 3: Measure 80 ml of niobium carbide suspension, add 100 mg of surfactant CTAB, add 0.5 mL of 5% Nafion solution and stir evenly; mix it with the electroless plating solution, make up the volume to 1000 ml, adjust the pH to 5.8, and obtain an electroless composite plating solution with a niobium carbide content of 0.08 g / L.

[0055] Example 4: Measure 100 ml of niobium carbide suspension, add 100 mg of surfactant CTAB, add 0.5 mL of 5% Nafion solution and stir evenly; mix it with the electroless plating solution, make up the volume to 1000 ml, adjust the pH to 5.8, and obtain an electroless composite plating solution with a niobium carbide content of 0.1 g / L.

[0056] Example 5: Measure 200 ml of niobium carbide suspension, add 100 mg of surfactant CTAB, add 0.5 mL of 5% Nafion solution and stir evenly; mix it with the electroless plating solution, make up the volume to 1000 ml, adjust the pH to 5.8, and obtain an electroless composite plating solution with a niobium carbide content of 0.2 g / L.

[0057] Example 6: Measure 300 ml of niobium carbide suspension, add 100 mg of surfactant CTAB, add 0.5 mL of 5% Nafion solution and stir evenly; mix it with the electroless plating solution, make up the volume to 1000 ml, adjust the pH to 5.8, and obtain an electroless composite plating solution with a niobium carbide content of 0.3 g / L.

[0058] The coating properties of the above examples were tested respectively, including hardness and wear resistance tests, uniformity tests. The mechanical properties were tested, including tensile strength tests and fatigue life tests.

[0059] Composite plating solutions with different niobium carbide concentrations were prepared according to the above six examples and subjected to electroless composite plating under the same conditions.

[0060] The test methods are as follows: Coating properties: Use a microhardness tester to measure the coating hardness; use a wear tester to measure the wear resistance.

[0061] Coating structure: Use a scanning electron microscope (SEM) to observe the microstructure of the coating.

[0062] Mechanical properties: Conduct a tensile test to determine the tensile strength; conduct a fatigue test to determine the fatigue life.

[0063] The experimental test results are shown in Table 1 below: Coating properties: Hardness: As the NbC content increases from 0.01 g / L to 0.1 g / L, the coating hardness gradually increases and reaches 450 HV. When the NbC content exceeds 0.1 g / L, the hardness decreases slightly. Wear resistance: The wear resistance decreases with the increase of NbC content, and the wear resistance is the lowest at 0.1 g / L, which is 1.6 mm³.

[0064] Mechanical properties: Tensile strength: When the NbC content is 0.1 g / L, the tensile strength is the highest, reaching 530 MPa. When the NbC content is too high, the tensile strength decreases. Fatigue life: When the NbC content is 0.1 g / L, the fatigue life is the longest, which is 180,000 cycles. High content will lead to a reduction in fatigue life.

[0065] Furthermore, the specimens of the above-mentioned embodiments are electroless plated on the Q235B substrate, and the performance of each sample is tested through electrochemical performance testing and corrosion resistance testing.

[0066] Prepare the plating solution according to the above six embodiments and carry out electroless plating under the same conditions.

[0067] Electrochemical performance testing: Use an electrochemical workstation to conduct polarization curve testing to measure the self-corrosion potential (Ecorr), corrosion current density (Icorr), and polarization resistance (Rp).

[0068] Corrosion resistance testing: Evaluate the corrosion resistance of the coating through salt spray testing or electrochemical impedance spectroscopy (EIS) testing.

[0069] The experimental test results are shown in Table 2 below: Example NbC content (g / L) Self-corrosion potential (mV vs. SCE) Corrosion current density (μA / cm²) Polarization resistance (Ω·cm²) Salt spray test time (hours) 1 0.01 -450 2.3 800 72 2 0.03 -430 2.1 900 96 3 0.08 -410 1.9 1000 120 4 0.1 -390 1.7 1100 168 5 0.2 -400 1.8 980 144 6 0.3 -420 2.0 950 120 Electrochemical performance Self-corrosion potential (Ecorr): As the NbC content increases, the self-corrosion potential gradually shifts positively, indicating a decrease in the corrosion tendency. At 0.1 g / L, the self-corrosion potential is the highest, which is -390 mV vs. SCE.

[0070] Corrosion current density (Icorr): The corrosion current density decreases with the increase of NbC content, and the minimum value is 1.7 μA / cm² at 0.1 g / L, indicating the lowest corrosion rate.

[0071] Polarization resistance (Rp): The polarization resistance increases with the increase of NbC content, and the maximum value is 1100 Ω·cm² at 0.1 g / L, indicating the strongest corrosion resistance of the coating.

[0072] Corrosion resistance Salt spray test time: The results of the salt spray test show that at 0.1 g / L, the corrosion resistance of the coating is the best and there are no obvious signs of corrosion for 168 hours. At other concentrations, the corrosion resistance decreases.

[0073] In summary, the optimal addition amount of NbC is 0.1 g / L because it shows the best results in terms of the coating properties, structure and mechanical properties, as well as the electrochemical and corrosion resistance properties of the coating. This indicates that 0.1 g / L is the best choice that balances all key performance indicators.

[0074] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a chemical composite plating solution based on niobium carbide nanoparticles, characterized in that, It includes the following steps: Step 1: Pretreat niobium carbide NbC powder to obtain a niobium carbide suspension mother liquor with uniform dispersion. The average particle size of NbC is 100 nm; Step 2: Prepare an electroless plating solution, the composition of which includes nickel chloride, sodium hypophosphite, sodium citrate, glycine, sodium acetate, sodium dodecylbenzenesulfonate, and zinc molybdate. Nickel chloride is the main salt, sodium hypophosphite is the reducing agent, sodium citrate is the main complexing agent, glycine is the auxiliary complexing agent, sodium acetate is the buffer, sodium dodecylbenzenesulfonate is the surfactant, and zinc molybdate is the stabilizer; Step 3: Measure the niobium carbide suspension described in Step 1, add a surfactant and a Nafion solution, and stir evenly; Step 4: Ultrasonically stir the niobium carbide suspension obtained in Step 3 to fully wet the niobium carbide particles; Step 5: Mix the niobium carbide suspension in Step 4 with the electroless plating solution, then stir evenly, and then dilute and make up the volume; Step 6: Ultrasonically stir the composite plating solution obtained in Step 5 to obtain an electroless composite plating solution.

2. The preparation method of a chemical composite plating solution based on niobium carbide nanoparticles according to claim 1, characterized in that, The preparation of the electroless plating solution includes the following steps: Step 21: Weigh the main salt, reducing agent, complexing agent, surfactant, and stabilizer in sequence according to the concentration ratio, and dissolve them separately with a small amount of distilled water; Step 22: Slowly pour the completely dissolved main salt solution into the uniformly mixed complexing agent solution in sequence; Step 23: Slowly pour the measured reducing agent solution into the solution prepared in Step 22; Step 24: Pour the stabilizer solution, buffer solution and other additives into the solution prepared in Step 23 respectively; Step 25: Dilute the above mixed solution with distilled water to near the target volume for volume making, and adjust the pH value with an AMP-95 solution and ammonia water; Step 26: Make up the volume, dilute to the specified volume with distilled water, and at the same time, calibrate and adjust the pH value again.

3. The preparation method of a chemical composite plating solution based on niobium carbide nanoparticles according to claim 1, characterized in that, The concentration of the niobium carbide suspension mother liquor is 1 g / L. The niobium carbide suspension in Step 5 is mixed with the electroless plating solution in proportion so that the content of niobium carbide in the electroless composite plating solution is 0.01 - 0.3 g / L.

4. The preparation method of a chemical composite plating solution based on niobium carbide nanoparticles according to claim 1 or 3, characterized in that, In Step 3, 200 mg of surfactant and 1 ml of 5% Nafion are added to every 100 ml of the niobium carbide suspension.

5. The preparation method of a chemical composite plating solution based on niobium carbide nanoparticles according to claim 1, characterized in that, The surfactant is cetyltrimethylammonium bromide (CTAB).

6. The preparation method of a chemical composite plating solution based on niobium carbide nanoparticles according to claim 1, characterized in that, In Step 4, the ultrasonic stirring time of the suspension is not less than 10 min. After dilution and volume making in Step 5, the pH value of the solution is adjusted to 5.

8.

7. The preparation method of a chemical composite plating solution based on niobium carbide nanoparticles according to claim 3, characterized in that, The content of niobium carbide in the electroless composite plating solution is 0.1 g / L.

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