A fastener coating and method of applying same

Abstract

A kind of fastener coating and its coating method, coating includes nylon net, coating and adjuvant, the nylon net is coated with coating and adjuvant, the coating method includes 1) pretreatment;Fastener surface is pretreated;Nylon net pre-dip treatment: nylon net is soaked in the mixed solution consisting of epoxy resin and polyvinyl alcohol, is soaked for more than 3min, obtains nylon net pre-coated piece;The content of polyvinyl alcohol in mixed solution is 1-30wt%;2) the nylon net pre-coated piece is covered on fastener surface, then is moulded, makes the nylon net pre-coated piece and fastener press together.This coating has the effect of insulation, anticorrosion, also has high wear resistance and tear resistance, and there is no falling, breaking appearance in stone impact, and has good dismounting performance, meets continuous large torque repeatedly dismounting 5 times more coating not broken.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a fastener coating and its application method. Background Technology

[0002] Corrosion is a widespread problem, especially for metallic materials (particularly magnesium alloys).

[0003] Magnesium alloys are lightweight and can be used in automotive, rail transportation, aerospace, and other fields. In some cases, magnesium alloy parts need to be fastened to parts made of other materials. When these connections are exposed to corrosive environments, magnesium alloys are prone to corrosion at the interface. This is because electrochemical corrosion easily occurs between dissimilar materials; typically, at the interface of dissimilar metals, the material with the lower potential is more susceptible to corrosion.

[0004] Corrosion prevention is usually achieved in two ways: one is to use a material with a lower potential as the anode and the material to be protected as the cathode, thus sacrificing the anode to protect the cathode; the other is to use physical isolation to prevent the material to be protected from corrosion.

[0005] Chinese Patent 202323242259.0 discloses a fastener with an anti-corrosion layer coated on its surface. The anti-corrosion layer is coated with a first coating, and the first coating is coated with a second coating. The materials of the first and second coatings include, but are not limited to, polytetrafluoroethylene, molybdenum coating, and chrome plating. The fastener surface is coated with a double-layer torque control coating to avoid the problem of uneven surface thickness of fasteners with only one layer of torque control coating, thereby reducing the standard deviation of torque coefficient and meeting customer needs.

[0006] Chinese Patent 202410539399.4 discloses a method for coating fastener surfaces. The dip coating used in this application contains at least phenolic resin, flake aluminum powder, ethylene glycol ethyl ether acetate, and polytetrafluoroethylene. Through two coating processes and pre-curing treatment, a uniform coating thickness can be achieved, resulting in a uniform coating thickness on the fastener surface that meets the needs of actual production.

[0007] Currently, the main problems with fastener surface coatings are: ① The coating has weak insulation properties and cannot prevent electrochemical corrosion; ② The coating has poor high-temperature stability and deforms after long-term use, leading to a decrease in fastening force; ③ The coating has poor durability and weak resistance to stone impact. Summary of the Invention

[0008] The purpose of this invention is to provide a fastener coating and its application method, which can meet the performance requirements of fastener surface such as insulation and corrosion resistance. In particular, the coating has excellent wear resistance and tear resistance, and can resist external environmental damage such as repeated disassembly and assembly and impact from gravel. Moreover, the application method is easy to construct and operate, and has low cost.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows:

[0010] A fastener coating includes a nylon mesh, a coating, and additives, wherein the nylon mesh is coated with the coating and additives, and the nylon mesh has a mesh count of 10-300.

[0011] Preferably, the coating is one or more of epoxy resin, polyurethane, and Teflon.

[0012] Preferably, the additive is polyvinyl alcohol, a plasticizer, or polyvinyl alcohol-vinyl acetate.

[0013] Preferably, the thickness of the nylon mesh is 10–300 μm.

[0014] The fastener coating application method of the present invention specifically includes the following steps:

[0015] 1) Pretreatment;

[0016] The fastener surface is pretreated;

[0017] Nylon mesh pre-impregnation treatment: Immerse the nylon mesh in a mixed solution of coating and additives for more than 3 minutes to obtain a pre-coated nylon mesh part; the content of additives in the mixed solution is 1-30 wt%;

[0018] 2) Cover the fastener surface with the pre-coated nylon mesh and then mold it to press the pre-coated nylon mesh and fastener together.

[0019] Preferably, the fasteners are further subjected to coloring and / or lubrication surface treatment.

[0020] Preferably, in step 1), the pretreatment includes shot peening, plasma treatment, and laser cleaning.

[0021] Preferably, in step 2), the immersion is carried out in a vacuum environment.

[0022] Preferably, in step 2), ultrasonic vibration is performed during the soaking process.

[0023] Preferably, the molding temperature is 100–250°C and the molding time is 1–30 min.

[0024] The fastener coating of this invention employs a combination of nylon mesh, coating, and additives. The nylon mesh serves to reinforce and toughen the coating when the fastener surface is subjected to abuse, and improves the wear resistance of the coating under friction. The coating (e.g., epoxy resin, polyurethane, Teflon, etc.) adheres the nylon mesh to the fastener surface. The additives (e.g., polyvinyl alcohol, plasticizers, polyvinyl alcohol-vinyl acetate copolymers, etc.) enhance the adhesion between the coating and the nylon mesh, preventing the coating from separating and peeling off.

[0025] Meanwhile, the nylon mesh and coating in the coating can effectively absorb electrons and reduce the flow of electrons in the material, thereby achieving good insulation performance. In addition, the added coating has strong interactions between polymer chains, which gives the coating a higher melting point, allowing it to maintain the stability of its physical and chemical properties in high-temperature environments, thus playing a good role in corrosion prevention.

[0026] Before coating, fasteners undergo surface pretreatment to improve coating performance. Pretreatment processes include, but are not limited to, removing surface sealing and passivation layers, and introducing adhesives. Specific implementation methods include shot peening, plasma treatment, and laser cleaning.

[0027] Nylon mesh pre-impregnation involves cutting the nylon mesh and immersing it in a mixed solution of coating (e.g., epoxy resin, polyurethane, Teflon) and additives (polyvinyl alcohol, polyvinyl alcohol-vinyl acetate) for at least 3 minutes to ensure thorough mixing. Adding 1-30 wt% polyvinyl alcohol to the mixed solution improves the compatibility between the nylon mesh and the coating. Furthermore, to reduce porosity between the nylon mesh and the coating, a vacuum environment or ultrasonic vibration can be used during pre-impregnation.

[0028] The pre-coated nylon mesh is placed over the surface of the fastener, and then molded using a mold that matches the fastener to firmly press the pre-coated nylon mesh onto the fastener. The molding temperature is controlled between 100-250℃, and the molding time is controlled between 1-30 minutes to allow the resin to fully cure.

[0029] Finally, the fasteners undergo surface treatment, including coloring and lubrication, such as coating with non-polar grease, solid lubricant, or surface painting, to ensure that the fastener surface meets additional performance requirements.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] This invention combines nylon mesh, coating, and additives to form a coating that is molded onto the surface of fasteners. By utilizing the properties of the nylon mesh and coating, the coating provides insulation and corrosion resistance. In addition, the nylon mesh enhances the coating's abrasion resistance and tear resistance, preventing it from peeling off or tearing under impact from gravel. It also has excellent disassembly and assembly performance, allowing the coating to withstand more than 5 repeated disassembly and assembly cycles under high torque without damage.

[0032] This invention utilizes a high-strength nylon mesh, which, with the aid of additives, is thoroughly mixed with a coating. The nylon mesh is then cured onto the fastener via molding. The additives and coating can penetrate the microporous structure of the nylon mesh, reducing air bubbles between the mesh and the coating, improving their adhesion, and preventing separation and peeling. If a layered coating method is used, the coating struggles to penetrate the mesh, resulting in numerous air bubbles around the mesh after curing. This also leads to easy separation between the mesh and coating layers, reducing the coating's wear resistance.

[0033] The coating of this invention allows pre-treated nylon mesh to be bonded to fasteners through molding, which is easy to construct and operate, low in cost, and suitable for large-scale production. Attached Figure Description

[0034] Figure 1 This is a photograph of the M8 nut prepared in Embodiment 1 of the present invention after being repeatedly disassembled and reassembled 5 times;

[0035] Figure 2 The fasteners were found to have broken and fallen off after being disassembled and reassembled twice. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings:

[0037] Example 1

[0038] The specific steps for applying the coating to M8 bolts are as follows:

[0039] 1) Preprocessing

[0040] Pre-treat the surface of the M8 fastener bolts by shot peening to remove oxides, oil, and sealing layers. The pre-treatment area is 5-10mm below the flange face from the bolt head. Areas that do not need to be sprayed are masked.

[0041] Nylon mesh prepreg treatment involves cutting a 100μm thick, 20-mesh nylon mesh into a predetermined shape, immersing the cut nylon mesh in a mixed solution of epoxy resin and polyvinyl alcohol, subjecting it to ultrasonic vibration during the immersion process, and soaking for 5 minutes to obtain a pre-coated nylon mesh part; the polyvinyl alcohol content in the mixed solution is 10wt%.

[0042] 2) Cover the area of ​​the M8 bolt surface that needs to be coated with the nylon mesh pre-coated part, and then perform molding to press the nylon mesh pre-coated part and the M8 bolt together. The molding temperature is 170℃ and the molding time is 30min.

[0043] 3) Apply solid lubricant to the flange surface of the bolt head.

[0044] The bolts made in Example 1, Teflon-treated bolts, and galvanized bolts were tightened into passivated magnesium alloy blocks with a tightening torque of 30 N·m. A neutral salt spray test was conducted according to GB / T 10125 standard, and the corrosion situation after 720 h is shown in Table 1.

[0045] Table 1

[0046]

[0047]

[0048] As can be seen from Table 1, the surface coating of the M8 bolt in the embodiment of the present invention did not show electrochemical corrosion in the corrosion test, while the surface of the M8 bolt with Teflon and zinc plating showed a corrosion depth of more than 3 mm.

[0049] The coating on the fasteners of this invention remains undamaged after five consecutive disassembly and reassembly cycles, while the coatings of traditional Teflon and galvanized fasteners show damage after only two disassembly and reassembly cycles.

[0050] Figure 1 The image shows the M8 nut prepared in Embodiment 1 of the present invention after being repeatedly disassembled and reassembled 5 times. As can be seen from the image, the surface coating was not damaged after being repeatedly disassembled and reassembled 5 times.

[0051] Figure 2 The photo shows an M8 nut with a Teflon coating after being disassembled and reassembled twice. As can be seen from the picture, the coating has been obviously damaged and peeled off.

[0052] Example 2

[0053] The specific steps for applying the coating to bolt washers are as follows:

[0054] 1) Preprocessing

[0055] The surface of the M8 fastener is pretreated by plasma treatment to remove oxides, oil, and sealing layers from the gasket surface.

[0056] Nylon mesh prepreg treatment involves cutting a 300μm thick, 300-mesh nylon mesh into a predetermined shape, immersing the cut nylon mesh in a mixed solution of polyurethane and plasticizer, subjecting it to ultrasonic vibration during immersion, and soaking for 15 minutes to obtain a pre-coated nylon mesh part; the polyvinyl alcohol content in the mixed solution is 20wt%.

[0057] 2) Cover the surface of the bolt washer with the pre-coated nylon mesh, and then perform molding to press the pre-coated nylon mesh and the bolt washer together. The molding temperature is 200℃ and the molding time is 10min.

[0058] 3) Apply solid lubricant to the flange surface of the gasket.

[0059] The gasket prepared in Example 2 was subjected to the SAE J400 standard stone impact test, and the coating on the gasket surface showed no peeling or damage.

[0060] Example 3

[0061] The specific steps for applying the coating to M8 nuts are as follows:

[0062] 1) Preprocessing

[0063] The surface of the M8 fastener is pretreated by shot peening to remove oxides, oil, and sealing layers from the nut surface. The pretreatment is performed on areas other than the threads, and the threads are masked.

[0064] For the pre-impregnation treatment of nylon mesh, firstly, according to the shape of the bolt head, cut the 150μm thick, 200-mesh nylon mesh into the predetermined shape, and then immerse the cut nylon mesh in a mixed solution composed of epoxy resin and polyvinyl alcohol. During the immersion process, ultrasonic vibration is performed, and the immersion time is 15 minutes to obtain the nylon mesh pre-coated part; the polyvinyl alcohol content in the mixed solution is 30wt%.

[0065] 2) Cover the surface of the M8 nut with the pre-coated nylon mesh, and then perform molding to press the pre-coated nylon mesh and the M8 nut together. The molding temperature is 150℃ and the molding time is 15min.

[0066] 3) Apply solid lubricant to the flange surface of the nut.

[0067] The nut made in Example 3 was tightened to a torque of 30 N·m and repeatedly tightened 5 times. The coating on the bolt surface did not peel off or break.

[0068] Example 4

[0069] The specific steps for applying the coating to M8 nuts are as follows:

[0070] 1) Preprocessing

[0071] The surface of the M8 fastener is pretreated by shot peening to remove oxides, oil, and sealing layers from the nut surface. The pretreatment is performed on areas other than the threads, and the threads are masked.

[0072] For the pre-impregnation treatment of nylon mesh, firstly, 10μm thick, 150-mesh nylon mesh is cut into a predetermined shape according to the shape of the bolt head. The cut nylon mesh is then immersed in a mixed solution of Teflon and polyvinyl alcohol-vinyl acetate. Ultrasonic vibration is performed during the immersion process. The immersion time is 15 minutes to obtain a pre-coated nylon mesh part. The content of polyvinyl alcohol-vinyl acetate in the mixed solution is 2wt%.

[0073] 2) Cover the surface of the M8 nut with the pre-coated nylon mesh, and then perform molding to press the pre-coated nylon mesh and the M8 nut together. The molding temperature is 150℃ and the molding time is 15min.

[0074] 3) Apply solid lubricant to the flange surface of the nut.

[0075] The nut made in Example 4 was tightened to a torque of 30 N·m and repeatedly tightened 5 times. The coating on the bolt surface did not peel off or break.

Claims

1. A fastener coating, characterized in that, It includes a nylon mesh, a coating, and additives, wherein the nylon mesh is coated with the coating and additives, and the nylon mesh has a mesh count of 10-300.

2. The fastener coating as described in claim 1, characterized in that, The coating is one or more of epoxy resin, polyurethane, and Teflon.

3. The fastener coating as described in claim 1, characterized in that, The additive is polyvinyl alcohol, plasticizer, or polyvinyl alcohol-vinyl acetate.

4. The fastener coating as described in claim 1, characterized in that, The thickness of the nylon mesh is 10–300 μm.

5. The method for applying a fastener coating as described in claim 1, 2, 3, or 4, characterized in that, Includes the following steps: 1) Pretreatment; The fastener surface is pretreated; Nylon mesh pre-impregnation treatment: Immerse the nylon mesh in a mixed solution of coating and additives for more than 3 minutes to obtain a pre-coated nylon mesh part; the content of additives in the mixed solution is 1-30 wt%; 2) Cover the fastener surface with the pre-coated nylon mesh and then mold it to press the pre-coated nylon mesh and fastener together.

6. The application method as described in claim 5, characterized in that, It also includes coloring and / or lubricating surface treatments for fasteners.

7. The application method as described in claim 5, characterized in that, In step 1), the pretreatment includes shot peening, plasma treatment, and laser cleaning.

8. The application method as described in claim 5, characterized in that, In step 2), the immersion is carried out in a vacuum environment.

9. The application method as described in claim 5 or 8, characterized in that, In step 2), ultrasonic vibration is performed during the soaking process.

10. The application method as described in claim 5, 8, or 9, characterized in that, In step 2), the molding temperature is 100-250℃ and the molding time is 1-30 min.

Images