A method for preparing a modified composite coating for wear and corrosion resistance on a hardware surface

Abstract

The application discloses a preparation method of a wear-resistant and corrosion-resistant modified composite coating on a hardware product surface, and belongs to the technical field of metal surface modification. The method generates a ceramic base layer containing a nano silicon carbide reinforcing phase on the hardware product surface in situ through double-frequency double-pulse plasma electrolytic oxidation, then uniformly penetrates fluorine-containing organic silicon resin into the micropore inside the ceramic layer by using a supercritical carbon dioxide fluid impregnation technology, and finally forms a gradient structure composite coating through low-temperature plasma solidification. The composite coating prepared by the application has high bonding strength with the substrate, the surface hardness can reach above 1200HV, the friction coefficient is below 0.25, the self-corrosion current is below 5*10 ‑11 A / cm² in a 3.5% sodium chloride solution, simultaneously has excellent water scale adhesion resistance and aging resistance, and can be widely applied to the surface protection of hardware products in the fields of kitchen and bathroom, ocean engineering, mechanical manufacturing and the like.

Description

Technical Field

[0001] This invention belongs to the field of metal surface modification technology, specifically relating to a method for preparing a wear-resistant and corrosion-resistant modified composite coating for the surface of hardware products. Background Technology

[0002] Hardware products are widely used in various fields such as kitchen and bathroom appliances, marine engineering, machinery manufacturing, and building decoration. Their surface properties directly affect the product's service life and performance. In actual use, hardware products often face problems such as corrosion, wear, and scale buildup, leading to damage to the product's appearance, functional failure, and even safety accidents.

[0003] Currently, surface protection for hardware products mainly employs technologies such as electroplating, chemical plating, spraying, and micro-arc oxidation. While electroplating technology is mature, it suffers from serious environmental pollution and limited coating adhesion. Spraying produces coatings with low bonding strength to the substrate, making them prone to peeling. Although ceramic coatings prepared using traditional micro-arc oxidation technology have high hardness and good corrosion resistance, the coating surface contains numerous micropores and cracks, which can easily become channels for corrosive media to penetrate. Furthermore, the coating has a high coefficient of friction, and its wear resistance needs further improvement.

[0004] To address these issues, researchers have developed various composite coating technologies. For example, they have performed pore-sealing treatments on the surface of micro-arc oxidation coatings or introduced reinforcing phases into the coating to improve wear resistance. However, existing pore-sealing technologies struggle to fully penetrate the sealing agent into the micropores within the coating, resulting in limited sealing effectiveness. Introducing reinforcing phases into the coating often suffers from uneven distribution and poor adhesion to the substrate. Therefore, developing a simple, environmentally friendly, efficient, and high-performance composite coating method for wear-resistant and corrosion-resistant modified coatings on hardware products is of significant practical importance. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a wear-resistant and corrosion-resistant modified composite coating on the surface of hardware products. This method involves generating a ceramic substrate layer containing a nano-silicon carbide reinforcing phase in situ on the surface of the hardware product using dual-frequency dual-pulse plasma electrolytic oxidation technology. Then, a supercritical carbon dioxide fluid impregnation technology is used to uniformly penetrate a fluorinated organosilicon resin into the micropores of the ceramic layer. Finally, low-temperature plasma curing is performed to form a gradient structure composite coating. The composite coating prepared by this invention has high bonding strength with the substrate and also possesses excellent wear resistance, corrosion resistance, scale adhesion resistance, and aging resistance.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a wear-resistant and corrosion-resistant modified composite coating on the surface of hardware products includes the following steps:

[0008] Surface pretreatment of the hardware product substrate;

[0009] The pretreated substrate was placed in an electrolyte and subjected to plasma electrolytic oxidation treatment using a dual-frequency dual-pulse power supply to generate a ceramic substrate layer containing nano-silicon carbide reinforcing phase in situ on the substrate surface.

[0010] The substrate with the ceramic substrate layer is placed in a supercritical reactor and impregnated with supercritical carbon dioxide fluid containing fluorinated organosilicon resin.

[0011] The impregnated substrate is subjected to low-temperature plasma curing treatment to obtain a wear-resistant and corrosion-resistant modified composite coating.

[0012] Further, the surface pretreatment in step (1) includes mechanical polishing, ultrasonic degreasing, deionized water cleaning, and drying in sequence. Mechanical polishing uses 320#, 600#, 1000#, and 1500# silicon carbide sandpaper to polish the substrate surface in sequence to remove surface oxide scale and scratches; ultrasonic degreasing uses a 95% ethanol solution and ultrasonic time is 10-15 minutes; deionized water cleaning time is 5-10 minutes; drying is done by cold air blowing.

[0013] Furthermore, in step (2), the electrolyte is composed of sodium silicate, sodium hexametaphosphate, potassium hydroxide, nano-silicon carbide particles, and deionized water. The concentration of sodium silicate is 10 g / L-20 g / L, the concentration of sodium hexametaphosphate is 5 g / L-15 g / L, the concentration of potassium hydroxide is 2 g / L-5 g / L, and the concentration of nano-silicon carbide particles is 1 g / L-5 g / L.

[0014] Furthermore, in step (2), the high-frequency dual-pulse power supply has a frequency of 1000Hz-2000Hz, a low-frequency frequency of 50Hz-100Hz, a positive pulse voltage of 300V-500V, a negative pulse voltage of 50V-150V, a duty cycle of 10%-30%, and a processing time of 20min-60min. The electrolyte temperature is controlled at 20℃-40℃.

[0015] Furthermore, in step (2), the thickness of the ceramic substrate layer is 10μm-30μm, and the particle size of the nano-silicon carbide reinforcing phase is 20nm-50nm. The nano-silicon carbide reinforcing phase is uniformly distributed in the ceramic substrate layer, playing a role in dispersion reinforcement and improving the hardness and wear resistance of the coating.

[0016] Furthermore, in step (3), the mass fraction of the fluorinated silicone resin is 5%-15%, the pressure of the supercritical carbon dioxide fluid is 10MPa-20MPa, the temperature is 40℃-60℃, and the impregnation time is 30min-90min. The supercritical carbon dioxide fluid has the characteristics of low viscosity and high diffusivity, which can uniformly penetrate the fluorinated silicone resin into the micropores and cracks inside the ceramic substrate, achieving complete pore sealing.

[0017] Furthermore, in step (3), the stirring rate of the supercritical reactor is 200 rpm to 500 rpm to ensure that the fluorinated organosilicon resin is uniformly dispersed in the supercritical carbon dioxide fluid.

[0018] Furthermore, in step (4), the low-temperature plasma curing uses argon plasma with a power of 100W-300W, a processing time of 10min-30min, and a processing temperature of 60℃-80℃. Low-temperature plasma curing enables the fluorinated silicone resin to undergo a cross-linking reaction, forming a dense organic-inorganic composite layer, while avoiding the influence of high temperature on the coating performance.

[0019] Furthermore, the base material of the hardware product is iron, iron alloy, copper, copper alloy, aluminum, aluminum alloy, or stainless steel.

[0020] The present invention also provides a wear-resistant and corrosion-resistant modified composite coating for the surface of hardware products obtained according to the above preparation method.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] This invention employs dual-frequency dual-pulse plasma electrolytic oxidation technology, which can effectively control the growth process of ceramic coatings, reduce the generation of micropores and cracks on the coating surface, and simultaneously generate nano-silicon carbide reinforcing phases in situ within the coating, significantly improving the hardness and wear resistance of the coating.

[0023] This invention employs supercritical carbon dioxide fluid impregnation technology, utilizing the low viscosity and high diffusivity of supercritical carbon dioxide fluid to completely penetrate fluorinated organosilicon resin into the micropores and cracks inside the ceramic substrate, achieving thorough pore sealing and significantly improving the corrosion resistance of the coating.

[0024] This invention employs low-temperature plasma curing technology, which enables fluorinated organosilicon resin to undergo a cross-linking reaction at low temperatures, forming a dense organic-inorganic composite layer. At the same time, it avoids the influence of high temperatures on coating performance and improves the bonding strength between the coating and the substrate.

[0025] The composite coating prepared by this invention has a gradient structure. The inner layer is a high-hardness ceramic substrate layer, which provides excellent wear resistance and corrosion resistance. The outer layer is a low surface energy organic-inorganic composite layer, which provides excellent resistance to scale adhesion and self-cleaning properties.

[0026] The present invention has a simple, environmentally friendly and efficient process, requires no complicated equipment, is easy to industrialize, and can be widely used in the surface protection of hardware products in the fields of kitchen and bathroom, marine engineering, and machinery manufacturing. Detailed Implementation

[0027] This embodiment provides a method for preparing a wear-resistant and corrosion-resistant modified composite coating on the surface of hardware products. The specific steps are as follows:

[0028] Surface pretreatment: 304 stainless steel is selected as the base material. The surface of the base material is polished in sequence with 320#, 600#, 1000# and 1500# silicon carbide sandpaper to remove the surface oxide scale and scratches. Then, the base material is immersed in a 95% ethanol solution for ultrasonic degreasing for 10 minutes. After removal, it is rinsed with deionized water for 5 minutes. Finally, it is dried with cold air for later use.

[0029] Plasma electrolytic oxidation treatment: An electrolyte was prepared with sodium silicate concentration of 15 g / L, sodium hexametaphosphate concentration of 10 g / L, potassium hydroxide concentration of 3 g / L, and silicon carbide nanoparticle concentration of 3 g / L, using deionized water as the solvent. The pretreated substrate was used as the anode, and a stainless steel plate as the cathode, both immersed in the electrolyte. A dual-frequency dual-pulse power supply was used for treatment, with a high frequency of 1500 Hz, a low frequency of 75 Hz, a positive pulse voltage of 400 V, a negative pulse voltage of 100 V, a duty cycle of 20%, and a treatment time of 40 min. The electrolyte temperature was controlled at 30 ℃. After treatment, the substrate was removed, washed with deionized water, and dried with cold air to obtain a ceramic substrate layer containing a silicon carbide nanoparticle-reinforced phase with a thickness of 20 μm.

[0030] Supercritical carbon dioxide fluid impregnation treatment: The substrate with the ceramic substrate layer is placed in a supercritical reactor; a fluorinated organosilicon resin solution is prepared, wherein the mass fraction of the fluorinated organosilicon resin is 10% and the solvent is anhydrous ethanol; the fluorinated organosilicon resin solution is added to the supercritical reactor; carbon dioxide fluid is introduced to raise the pressure in the reactor to 15 MPa, the temperature to 50 °C, the stirring rate to 350 rpm, and the impregnation time to 60 min; after impregnation, the pressure is slowly released and the substrate is removed.

[0031] Low-temperature plasma curing treatment: The impregnated substrate is placed in a plasma treatment device, argon gas is introduced, the power is adjusted to 200W, the treatment time is 20min, and the treatment temperature is 70℃; after the treatment is completed, the substrate is removed to obtain a wear-resistant and corrosion-resistant modified composite coating.

[0032] Example 1

[0033] This embodiment provides a method for preparing a wear-resistant and corrosion-resistant modified composite coating on the surface of hardware products. The specific steps are as follows:

[0034] Surface pretreatment: Brass was selected as the base material. The surface of the base was polished in sequence with 320#, 600#, 1000# and 1500# silicon carbide sandpaper to remove the oxide scale and scratches. Then the base was placed in a 95% ethanol solution for ultrasonic degreasing for 12 minutes. After removal, it was rinsed with deionized water for 7 minutes. Finally, it was dried with cold air for later use.

[0035] Plasma electrolytic oxidation treatment: An electrolyte was prepared with sodium silicate concentration of 12 g / L, sodium hexametaphosphate concentration of 8 g / L, potassium hydroxide concentration of 2.5 g / L, and nano-silicon carbide particle concentration of 2 g / L, using deionized water as the solvent. The pretreated substrate was used as the anode, and a stainless steel plate as the cathode, and placed in the electrolyte. A dual-frequency dual-pulse power supply was used for treatment, with a high frequency of 1200 Hz, a low frequency of 60 Hz, a positive pulse voltage of 350 V, a negative pulse voltage of 80 V, a duty cycle of 15%, and a treatment time of 30 min. The electrolyte temperature was controlled at 25 ℃. After treatment, the substrate was removed, washed with deionized water, and dried with cold air to obtain a ceramic substrate layer containing nano-silicon carbide reinforcing phase with a thickness of 15 μm.

[0036] Supercritical carbon dioxide impregnation treatment: The substrate with the ceramic substrate layer is placed in a supercritical reactor; a fluorinated organosilicon resin solution is prepared, wherein the mass fraction of the fluorinated organosilicon resin is 8%, and the solvent is anhydrous ethanol; the fluorinated organosilicon resin solution is added to the supercritical reactor; carbon dioxide fluid is introduced to raise the pressure in the reactor to 12 MPa, the temperature to 45°C, the stirring rate to 300 rpm, and the impregnation time to 45 min; after impregnation, the pressure is slowly released and the substrate is removed.

[0037] Low-temperature plasma curing treatment: The impregnated substrate is placed in a plasma treatment device, argon gas is introduced, the power is adjusted to 150W, the treatment time is 15min, and the treatment temperature is 65℃; after the treatment is completed, the substrate is removed to obtain a wear-resistant and corrosion-resistant modified composite coating.

[0038] Example 2

[0039] This embodiment provides a method for preparing a wear-resistant and corrosion-resistant modified composite coating on the surface of hardware products. The specific steps are as follows:

[0040] Surface pretreatment: 6061 aluminum alloy was selected as the base material. The surface of the base material was polished in sequence with 320#, 600#, 1000# and 1500# silicon carbide sandpaper to remove the surface oxide scale and scratches. Then the base material was placed in a 95% ethanol solution for ultrasonic degreasing for 15 minutes. After removal, it was rinsed with deionized water for 10 minutes. Finally, it was dried with cold air for later use.

[0041] Plasma electrolytic oxidation treatment: An electrolyte was prepared with sodium silicate concentration of 18 g / L, sodium hexametaphosphate concentration of 12 g / L, potassium hydroxide concentration of 4 g / L, and nano-silicon carbide particle concentration of 4 g / L, using deionized water as the solvent. The pretreated substrate was used as the anode, and a stainless steel plate was used as the cathode, both immersed in the electrolyte. A dual-frequency dual-pulse power supply was used for treatment, with a high frequency of 1800 Hz, a low frequency of 90 Hz, a positive pulse voltage of 450 V, a negative pulse voltage of 120 V, a duty cycle of 25%, and a treatment time of 50 min. The electrolyte temperature was controlled at 35 ℃. After treatment, the substrate was removed, washed with deionized water, and dried with cold air to obtain a ceramic substrate layer containing nano-silicon carbide reinforcing phase with a thickness of 25 μm.

[0042] Supercritical carbon dioxide impregnation treatment: The substrate with the ceramic substrate layer is placed in a supercritical reactor; a fluorinated organosilicon resin solution is prepared, wherein the mass fraction of the fluorinated organosilicon resin is 12% and the solvent is anhydrous ethanol; the fluorinated organosilicon resin solution is added to the supercritical reactor; carbon dioxide fluid is introduced to raise the pressure in the reactor to 18 MPa, the temperature to 55 °C, the stirring rate to 400 rpm, and the impregnation time to 75 min; after impregnation, the pressure is slowly released and the substrate is removed.

[0043] Low-temperature plasma curing treatment: The impregnated substrate is placed in a plasma treatment device, argon gas is introduced, the power is adjusted to 250W, the treatment time is 25min, and the treatment temperature is 75℃; after the treatment is completed, the substrate is removed to obtain a wear-resistant and corrosion-resistant modified composite coating.

[0044] Performance testing

[0045] The performance of the composite coatings prepared in Examples 1-3 was tested, and the test results are shown in the table below:

[0046]

[0047] The test results show that the composite coating prepared by this invention has excellent comprehensive performance, high surface hardness, low coefficient of friction, good corrosion resistance, high bonding strength with the substrate, and good hydrophobicity and aging resistance, which can meet the requirements of hardware products in various complex environments.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a wear-resistant and corrosion-resistant modified composite coating on the surface of hardware products, characterized in that, Includes the following steps: a. Surface pretreatment of the hardware product substrate; b. The pretreated substrate is placed in an electrolyte and subjected to plasma electrolytic oxidation treatment using a dual-frequency dual-pulse power supply to generate a ceramic substrate layer containing nano-silicon carbide reinforcing phase in situ on the substrate surface; The electrolyte is composed of sodium silicate 10g / L-20g / L, sodium hexametaphosphate 5g / L-15g / L, potassium hydroxide 2g / L-5g / L, nano silicon carbide particles 1g / L-5g / L and deionized water. The dual-frequency dual-pulse power supply has a high frequency of 1000Hz-2000Hz, a low frequency of 50Hz-100Hz, a positive pulse voltage of 300V-500V, a negative pulse voltage of 50V-150V, a duty cycle of 10%-30%, and a processing time of 20min-60min. The thickness of the ceramic substrate layer is 10μm-30μm, and the particle size of the nano-silicon carbide reinforcing phase is 20nm-50nm. c. Place the substrate with the ceramic substrate layer in a supercritical reactor and pass supercritical carbon dioxide fluid containing fluorinated organosilicon resin through it for impregnation treatment. The fluorinated organosilicon resin has a mass fraction of 5%-15%, the supercritical carbon dioxide fluid has a pressure of 10MPa-20MPa, a temperature of 40℃-60℃, and an impregnation time of 30min-90min. d. The impregnated substrate is subjected to low-temperature plasma curing treatment to obtain a wear-resistant and corrosion-resistant modified composite coating; The low-temperature plasma curing uses argon plasma with a power of 100W-300W, a processing time of 10min-30min, and a processing temperature of 60℃-80℃.

2. The preparation method according to claim 1, characterized in that, The surface pretreatment in step a includes mechanical polishing, ultrasonic degreasing, deionized water cleaning and drying in sequence; the mechanical polishing uses 320#, 600#, 1000# and 1500# silicon carbide sandpaper to polish the substrate surface in sequence; the ultrasonic degreasing uses a 95% ethanol solution and the ultrasonic time is 10min-15min.

3. The preparation method according to claim 1, characterized in that, In step c, the stirring rate of the supercritical reactor is 200 rpm to 500 rpm.

4. The preparation method according to claim 1, characterized in that, The base material of the hardware product is iron, iron alloy, copper, copper alloy, aluminum, or aluminum alloy.

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