A preparation process for a nickel-phosphorus alloy coating on the surface of alumina fibers

Abstract

This invention belongs to the field of composite fiber material preparation technology, and relates to a process for preparing a nickel-phosphorus alloy coating on the surface of alumina fibers. The steps include dispersion, activation, and preparation of a plating solution. The main salt in the plating solution is any one of nickel sulfate, nickel chloride, or nickel acetate, with a concentration of 5-60 g / L. The reducing agent is sodium hypophosphite solution, and the pH of the plating solution is 11. Plating is then performed by placing the activated fibers in the plating solution, stirring slowly, and heating in a water bath at 50-80°C until the plating solution becomes clear. After plating, the fibers are removed and allowed to air dry naturally to obtain the product. This invention achieves the plating of a nickel-phosphorus alloy coating on the surface of alumina through chemical liquid phase deposition. The process is simple and low-cost. The prepared product exhibits excellent performance and stable quality.

Description

Technical Field

[0001] This invention belongs to the field of composite fiber material preparation technology, and relates to a preparation process of a nickel-phosphorus alloy coating on the surface of alumina fibers. Background Technology

[0002] Alumina fibers, due to their superior properties such as high specific modulus, specific strength, ablation resistance, and high-temperature insulation, are one of the commonly used reinforcements in metal matrix composites (MMCs). However, the wettability between alumina fibers and metals has always been a bottleneck problem restricting MMC preparation. While matrix alloying can improve wettability to some extent, it affects the high thermal conductivity of the matrix and can also cause adverse reactions between the fibers and the metal, leading to damage to the reinforcing fibers and weakening the role of the reinforcement in improving the performance of the composite material. Fiber surface metallization can effectively improve the wettability between the fiber reinforcement and the molten metal, and is currently a popular research direction. However, current techniques require the fibers to undergo degreasing, roughening, sensitization, and activation processes before plating. The degreasing and roughening process can easily damage the fiber surface, leading to unstable product performance and a high defect rate. The palladium salts commonly used in the activation process are too expensive, resulting in high production costs. In addition, due to the difficulty of nickel plating, some processes use high-pressure hydrogen reduction, which has a high risk factor and is not suitable for industrial application.

[0003] Nickel-phosphorus alloys have superior corrosion resistance compared to other alloys, making them suitable for use in highly corrosive environments. However, current processes cannot deposit nickel-phosphorus alloys onto the surface of alumina fibers. Summary of the Invention

[0004] This invention proposes a novel process for preparing a nickel-phosphorus alloy coating on the surface of alumina fibers, addressing the problems existing in the traditional nickel plating process for alumina fibers.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0006] A process for preparing a nickel-phosphorus alloy coating on the surface of alumina fibers, comprising the following steps:

[0007] (1) Dispersion: Add alumina fibers to the dispersion, sonicate, and then wash.

[0008] (2) Activation: Mix KH650 solution and silver nitrate solution to obtain activation solution. Soak the washed fibers in the activation solution for 10-20 minutes at a temperature of 30-50℃.

[0009] (3) Preparation of plating solution: Add main salt, complexing agent, reducing agent, stabilizer and 50% sodium hydroxide solution to deionized water in sequence and mix evenly to obtain plating solution. The main salt is any one of nickel sulfate, nickel chloride and nickel acetate. The concentration of main salt in the plating solution is 5-60 g / L. The reducing agent is sodium hypophosphite solution. The pH of the plating solution is 11.

[0010] (4) Plating: Place the activated fiber in the plating solution, stir slowly, heat the water bath at 50-80℃ for plating, and finish plating when the plating solution is clear. Take out the plating fiber and let it air dry naturally to obtain the product.

[0011] Preferably, the dispersion in step (1) is any one of sodium acetate, hexadecanoic acid, octadecanoic acid, octadecenoic acid, and boric acid.

[0012] Preferably, the concentration of KH650 in the activation solution of step (2) is 10-20 g / L and the concentration of silver nitrate is 10-30 g / L.

[0013] Preferably, in step (3), the complexing agent is any one of sodium citrate, glycolic acid, and lactic acid, and the stabilizer is any one of ammonium chloride, sodium iodate, and thiourea; the concentration of the complexing agent in the plating solution is 10-60 g / L, the concentration of the reducing agent is 4-40 g / L, and the concentration of the stabilizer is 5-40 g / L.

[0014] Preferably, the stirring rate in step (4) is 50-100 rpm and the plating time is 20-30 min.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0016] 1. This invention enables the application of a nickel-phosphorus alloy coating on the surface of alumina through chemical liquid phase deposition. The process is simple and the cost is low.

[0017] 2. The prepared product has excellent performance and stable quality. Attached Figure Description

[0018] Figure 1 a is a SEM image of the coated alumina fiber from Example 1. Figure 1 b is a SEM image of the coated alumina fiber after immersion in the corrosive solution.

[0019] Figure 2 The image shows the EDS spectrum of the coated fiber in Example 1.

[0020] Figure 3 This is an elemental distribution diagram of the cross-section of the coated alumina fiber in Example 1.

[0021] Figure 4 This is an axial elemental distribution diagram of the coated alumina fiber in Example 1.

[0022] Figure 5 This is a SEM image of the coated alumina fiber for comparison example 1.

[0023] Figure 6 This is a SEM image of the modified fiber in Comparative Example 2.

[0024] Figure 7 The image shows the EDS spectrum of the coated fiber in Comparative Example 2.

[0025] Figure 8 This is a SEM image of the modified fiber in Comparative Example 3.

[0026] Figure 9 The image shows the EDS spectrum of the coated fiber in Comparative Example 3.

[0027] Figure 10 This is a SEM image of the modified fiber in Comparative Example 4.

[0028] Figure 11 The image shows the EDS spectrum of the coated fiber in Comparative Example 4. Detailed Implementation

[0029] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below with reference to specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0030] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0031] Example 1

[0032] This embodiment provides a process for preparing a nickel-phosphorus alloy coating on the surface of alumina fibers, and the specific steps are as follows.

[0033] Take 2g of continuous alumina fiber (commercially available, produced by Guozhuang New Material Technology (Jiangsu) Co., Ltd., brand name ML996); immerse the fiber in ultrasonic cleaning for 6 minutes, then use sodium acetate dispersion solution to disperse the fiber (enough to submerge it), and then remove and rinse with deionized water for at least 10 seconds until the fiber is clean; prepare 100ml of activation solution, ensuring that the KH650 concentration in the activation solution is 10g / L and the silver nitrate solution concentration is 15g / L. Place the dispersed and cleaned fiber into the activation solution and soak it at 40℃ for 10 minutes, then remove and rinse with deionized water. Add nickel sulfate (main salt), sodium citrate (complexing agent), sodium hypophosphite (reducing agent), ammonium chloride (stabilizer), and a 50% sodium hydroxide solution sequentially to the deionized water to prepare the plating solution. The plating solution contains a main salt concentration of 20g / L, a complexing agent concentration of 30g / L, a reducing agent concentration of 20g / L, and a stabilizer concentration of 20g / L. Finally, the pH of the plating solution was adjusted to 11 using a 50% sodium hydroxide solution. The fibers were then placed in the plating solution and heated in a water bath at 70°C. During the reaction, the plating solution was stirred slowly at a rate of 50 rpm until the solution became clear and the reaction stopped. The alumina fibers were then removed and allowed to air dry naturally, thus obtaining alumina fibers with a nickel-phosphorus alloy coating.

[0034] The obtained products are tested, such as Figures 1 to 4 As shown. Figure 1 SEM images of the fibers, from Figure 1 The resulting coating is smooth, dense, and complete. Figure 2 The EDS spectrum of the fiber shows that the coating deposits a large amount of nickel metal and a small amount of phosphorus. Figure 3 This is a diagram showing the elemental distribution across the cross-section of the fiber. Figure 4 This is a diagram showing the elemental distribution along the fiber axis. From... Figure 3 and Figure 4 It can be observed that the fiber forms a distinct core-sheath structure, and the nickel and phosphorus elements are evenly distributed on the fiber surface. At this time, the required nickel-phosphorus alloy coating is formed on the fiber surface.

[0035] Al2O3 fibers with a nickel-phosphorus alloy coating were immersed in a 6wt% NaCl solution for 48 h and 96 h, and the change in resistance was measured to test their corrosion resistance. The results are shown in Table 1 below.

[0036] Table 1. Changes in resistivity of nickel-phosphorus alloy coated fibers before and after immersion.

[0037]

[0038] As can be observed from Table 1, the change in resistance value after fiber soaking is small and remains within a reasonable range. Figure 1 a and Figure 1 b represents the surface morphology of the nickel-plated fiber before immersion, such as Figure 1It can be observed that the coating before corrosion was dense and intact, such as Figure 1 b. It can be observed that the coating surface remains intact after corrosion, with almost no change, indicating that the nickel-phosphorus alloy coating has excellent corrosion resistance.

[0039] Example 2

[0040] Take 2g of continuous alumina fiber; immerse the fiber in ultrasonic cleaning for 6 minutes, using hexadecanoic acid dispersion as the internal solution to disperse the fiber, then remove and rinse with deionized water for at least 10 seconds until the fiber is clean; take 100ml of activation solution containing 10g / L KH650 and 15g / L silver nitrate. Place the dispersed and cleaned fiber into the activation solution and soak at 30℃ for 15 minutes, then remove and rinse with deionized water. Prepare the plating solution by sequentially adding nickel sulfate (main salt), sodium citrate (complexing agent), sodium hypophosphite (reducing agent), ammonium chloride (stabilizer), and a 50% sodium hydroxide solution. The concentrations of the main salt, complexing agent, reducing agent, and stabilizer in the plating solution are 5g / L, 20g / L, 10g / L, and 15g / L, respectively. Finally, adjust the pH of the plating solution to 11 using a 50% sodium hydroxide solution. The fiber is then placed in the plating solution and heated in a water bath at 60°C. During the reaction, the plating solution is stirred slowly at a stirring rate of 70 rpm until the plating solution becomes clear and the reaction stops. The alumina fiber is then removed and allowed to air dry naturally to obtain alumina fiber with a nickel-phosphorus alloy coating.

[0041] Example 3

[0042] Take 2g of continuous alumina fiber; immerse the fiber in ultrasonic cleaning for 6 minutes, using boric acid dispersion as the internal solution to disperse the fiber, then remove and rinse with deionized water for at least 10 seconds until the fiber is clean; take 100ml of activation solution containing 20g / L KH650 and 30g / L silver nitrate, place the dispersed and cleaned fiber into the activation solution, soak at 50℃ for 20 minutes, then remove and rinse with deionized water. Prepare the plating solution by sequentially adding nickel sulfate (main salt), sodium citrate (complexing agent), sodium hypophosphite (reducing agent), ammonium chloride (stabilizer), and a 50% sodium hydroxide solution to the deionized water. The concentrations of the main salt, complexing agent, reducing agent, and stabilizer in the plating solution are 30g / L, 60g / L, 40g / L, and 40g / L, respectively. Finally, adjust the pH of the plating solution to 11 using a 50% sodium hydroxide solution. The fiber is then placed in the plating solution and heated in a water bath at 80°C. During the reaction, the plating solution is stirred slowly at a stirring rate of 100 rpm until the plating solution becomes clear and the reaction stops. The alumina fiber is then removed and allowed to air dry naturally to obtain alumina fiber with a nickel-phosphorus alloy coating.

[0043] Comparative Example 1

[0044] This comparative example modifies the concentration and ratio of the plating solution. The plating solution composition is: nickel sulfate 40 g / L as the main salt, sodium citrate 50 g / L as the complexing agent, sodium hypophosphite 30 g / L as the reducing agent, and ammonium chloride 5 g / L as the stabilizer. The pH of the plating solution is then adjusted to 11 using a 50% sodium hydroxide solution. The remaining steps are consistent with Example 1. The resulting nickel-phosphorus alloy coated alumina fibers are as follows... Figure 5 As shown. Figure 5 SEM images of modified fibers, from Figure 5 It can be seen that changing the plating process will affect the plating effect, resulting in uneven coating particles and a rough surface.

[0045] Comparative Example 2

[0046] This comparative example does not involve ultrasonic treatment of the fibers; the remaining steps are the same as in Example 1. The obtained fiber test results are as follows: Figures 6 to 7 As shown in the figure, changing the composition of the dispersion affects the plating effect. The coating particles are of varying sizes, resulting in a rough and incomplete surface, making it impossible to form a complete coating. Furthermore, the energy dispersive spectroscopy (EDS) spectrum shows a decrease in nickel metal content and the absence of phosphorus, making it impossible to form a nickel-phosphorus alloy coating, resulting in a very poor plating effect.

[0047] Comparative Example 3

[0048] This comparative example alters the immersion temperature during activation treatment, setting it to room temperature; the remaining preparation process is the same as in Example 1. The product is attached. Figure 8 and attached Figure 9 As shown in the figure, the coating particles are of varying sizes and have incomplete surfaces, making it impossible to form a complete coating. The nickel content is extremely low, and there is no phosphorus element present.

[0049] Comparative Example 4

[0050] This comparative example does not involve fiber dispersion treatment; the remaining steps are the same as in Example 1. Product test results are attached. Figure 10 and 11 As shown in the figure, failing to disperse the fibers will severely affect the plating effect; the fiber surface has almost no particle deposition, and is covered with... Figure 11 Energy dispersive spectroscopy revealed that the nickel content on the fiber surface was only 1.41 wt%, with no phosphorus present, indicating that the dispersion treatment step plays a crucial role in this process.

[0051] This invention disperses continuous alumina fibers to maximize contact with noble metal ions on the fiber surface, increasing reaction activation points. Simultaneously, it modifies other pretreatment steps by using a silane coupling agent combined with silver ions to achieve effective metal deposition, facilitating subsequent plating and resulting in a nickel-phosphorus alloy coating on the alumina fiber surface. The nickel-phosphorus coating can be effectively prepared on the surface of continuous alumina fibers using a chemical liquid phase deposition process. The entire process is simple and convenient, with low preparation costs and a novel pretreatment concept, making it the first domestic process to achieve nickel-phosphorus alloy deposition on the surface of alumina fibers.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A process for the preparation of a nickel-phosphorus alloy coating on the surface of an alumina fiber, characterized in that, The steps are as follows: (1) dispersion: take the alumina fiber into the dispersion liquid, ultrasonic treatment, and then wash; (2) activation: mix the kh650 solution and the silver nitrate solution to obtain an activation liquid, and immerse the washed fiber in the activation liquid for 10-20 min, with the immersion temperature being 30-50℃; (3) preparation of plating solution: sequentially add the main salt, complexing agent, reducing agent, stabilizer, and 50% sodium hydroxide solution into the deionized water to obtain the plating solution, wherein the main salt is any one of nickel sulfate, nickel chloride, and nickel acetate, the concentration of the main salt in the plating solution is 5-30 g / L, the reducing agent is sodium hypophosphite solution, and the pH of the plating solution is 11; (4) plating: place the activated fiber in the plating solution, slowly stir, and heat in a water bath at 50-80℃ to perform plating until the plating solution is clear, and then take out the plated fiber to naturally dry to obtain the product; The dispersion liquid in step (1) is any one of sodium acetate, hexadecanoic acid, octadecanoic acid, octadecenoic acid, and boric acid; The concentration of kh650 in the activation liquid in step (2) is 10-20 g / L, and the concentration of silver nitrate is 10-30 g / L; The complexing agent in step (3) is any one of sodium citrate, glycolic acid, and lactic acid, and the stabilizer is any one of ammonium chloride, sodium iodate, and thiourea; the concentration of the complexing agent in the plating solution is 10-30 g / L, the concentration of the reducing agent is 4-20 g / L, and the concentration of the stabilizer is 15-40 g / L.

2. The process for preparing a nickel-phosphorus alloy coating on the surface of alumina fibers according to claim 1, characterized in that, The stirring rate in step (4) is 50-100 rpm, and the plating time is 20-30 min.

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