A diamond microparticle coating liquid, a method for preparing the same, and a connection assembly

Abstract

The application discloses a kind of diamond microparticle coating fluid and its preparation method and connecting assembly, it is related to vehicle technical field.Diamond microparticle coating fluid raw materials include: diamond microparticle, dispersing agent, film forming agent, corrosion inhibitor, coupling agent and solvent.The coupling agent includes at least one of titanate coupling agent, aluminate coupling agent, silane coupling agent.The diamond microparticle has strong bonding capacity by adding coupling agent in diamond microparticle coating fluid, can form close connection between connecting surface and connecting surface piece when being applied, without using high viscosity adhesive, without forming relatively thick coating, so that diamond microparticle does not need to be coated inside coating, so that fully exposed diamond microparticle can be embedded inside connecting piece, reduce sliding wear between connecting piece and connecting piece, reduce bolt loosening and fracture problems.

Description

Technical Field

[0001] This application relates to the field of automotive technology, and in particular to a diamond microparticle coating liquid, its preparation method, and connecting components. Background Technology

[0002] Sliding wear between the mating surfaces of connected parts, which can further develop into bolt loosening and breakage, is a common phenomenon in connection failures. This is especially true when the connection structure is subjected to large external loads. Sliding wear can easily lead to damage to the paint film of the connected parts, resulting in localized corrosion. If it continues to develop, the combined effect of high dynamic tensile stress and fretting wear can cause fretting fatigue cracking in the connected parts, or bolts to loosen or fracture due to abnormal dynamic stress. Summary of the Invention

[0003] This application provides a diamond microparticle coating liquid, its preparation method, and a connecting component to solve the problem of sliding wear between the mating surfaces of existing connectors, which can further develop into bolt loosening and breakage.

[0004] In a first aspect, this application provides a diamond microparticle coating liquid, the raw materials of which include:

[0005] Diamond microparticles, dispersants, film-forming agents, corrosion inhibitors, coupling agents, and solvents;

[0006] The coupling agent includes at least one of titanate coupling agents, aluminate coupling agents, and silane coupling agents.

[0007] This application adds a coupling agent to the diamond microparticle coating liquid, giving the diamond microparticles strong coupling properties. This allows them to form a tight bond with the connected parts when coated on the joint surface, eliminating the need for high-viscosity adhesives and thick coatings. This eliminates the need for the diamond microparticles to be encapsulated within the coating, allowing the fully exposed diamond microparticles to embed inside the connected parts. This avoids sliding wear between the first and second connected parts and reduces problems such as bolt loosening and breakage.

[0008] It should be noted that coupling agents containing at least one of titanate, aluminate, or silane coupling agents have the advantage of enhancing the adhesion between diamond and the film layer compared to other types of coupling agents. Furthermore, due to the widespread bonding ability of coupling agents with various materials, the surfaces of the joined parts can be bare metal, anodic protective coatings such as zinc plating, or common paint coatings. Utilizing the chemical bonding mechanism of the coupling agent, a thin but strongly adhesive coupling agent coating layer can be formed on the mounting surface, thus fully exposing the tips of the diamond particles and facilitating their embedding / biting into the joined surface material. Typically, a layer of coupling agent is pre-applied to the connector, followed by a diamond particle coating liquid on the coupling agent surface to improve the bonding strength between the diamond particles and the connector.

[0009] In some embodiments, the diamond microparticles account for 10% to 30% of the mass of the diamond microparticle coating liquid. This mass percentage allows the diamond microparticles to occupy 10% to 80% of the surface area after the coating is formed, thereby increasing the friction between the connector and the connected parts and reducing sliding wear between them; and / or,

[0010] The coupling agent comprises 3% to 5% by mass in the diamond microparticle coating solution. Within this range, the coupling agent can improve the bonding strength between the diamond microparticles and the connector, further reduce the coating thickness, expose and protrude the diamond microparticles from the coating surface, making them easier to embed into the connected components, increasing the coefficient of friction between the connector and the connected components, and reducing sliding wear; and / or,

[0011] The diamond microparticles have a particle size of 5 to 60 μm. Within this range, the diamond microparticles are more easily exposed on the coating surface, making it easier for them to embed into the connected parts, thereby increasing the coefficient of friction between the connector and the connected parts and reducing sliding wear.

[0012] In some embodiments, the mass ratio of the dispersant, film-forming agent, corrosion inhibitor, and solvent is (10–25):(28–40):(0.5–1):(30.6–36). This mass ratio allows for a lower viscosity of the diamond microparticle coating solution, resulting in a thinner coating. This facilitates the exposure of diamond microparticles to the coating surface, making it easier for the diamond microparticles to embed into the connected components, increasing the coefficient of friction between the connector and the connected components, and reducing sliding wear. It should be noted that the addition of a coupling agent prevents the amount of film-forming agent from becoming excessive, thus controlling the coating thickness.

[0013] In some embodiments, the dispersant includes at least one of sodium petroleum sulfonate, sodium oleate, and sodium phthalate. Using at least one of these dispersants can fully disperse various components and simultaneously enhance the dispersion performance of diamond during stirring; and / or,

[0014] The film-forming agent includes at least one of monoglyceride fatty acid ester and propylene glycol methyl ether acetate. Using at least one of the above film-forming agents, a thin and dense film layer can be formed on the surface of the part; and / or,

[0015] The corrosion inhibitor includes at least one of benzotriazole, phosphonic acid, and mercaptobenzothiazole. Using at least one of these corrosion inhibitors can reduce erosion of the part surface and improve the rust prevention performance when coated on the bare surface of the part; and / or,

[0016] The solvent includes at least one of polyalphaolefin synthetic oil, carboxylic acid ester synthetic oil, and ester synthetic oil. Using at least one of the above solvents can provide a stable dispersion environment and rapid drying performance.

[0017] In some embodiments, the raw materials also include colorants. Dispersants, film-forming agents, corrosion inhibitors, and solvents are typically transparent and colorless, making it difficult to see whether the coating is complete and to observe the coating area during coating. Therefore, colorants can be added to the diamond microparticle coating solution to make the coating easier to identify and determine whether the coating is complete. Bright colors, such as yellow, red, blue, green, purple, and orange, can be used. To reduce the impact of the colorant on the overall diamond microparticle coating solution system, azo-type colorants can be selected. The mass percentage of the colorant in the entire diamond microparticle coating solution can be 0.3% to 0.5%.

[0018] Secondly, this application provides a method for preparing a diamond microparticle coating liquid, comprising the following steps:

[0019] The dispersant, film-forming agent, corrosion inhibitor, and solvent are mixed to obtain the first mixture;

[0020] Diamond microparticles are mixed with a coupling agent to obtain a second mixture;

[0021] The first mixture and the second mixture are mixed to obtain a diamond microparticle coating solution.

[0022] By mixing diamond microparticles with a coupling agent to obtain a second mixture, the diamond microparticles can be fully coupled, which is beneficial for the diamond microparticles to adhere firmly to the bonding surface of the connected parts. This allows the viscosity of the diamond microparticle coating liquid to be lower, the coating thickness to be thinner, and the diamond microparticles to be exposed on the surface of the coating. This makes it easier for the diamond microparticles to embed into the connected parts, increases the coefficient of friction between the first and second connected parts, and reduces sliding wear.

[0023] In some embodiments, mixing the diamond microparticles with the coupling agent to obtain a second mixture includes:

[0024] Diamond microparticles are mixed with an excess of coupling agent to obtain a premixed solution;

[0025] Stir the premixed solution, let it stand, separate the layers, and separate the excess coupling agent in the upper layer to obtain the second mixture.

[0026] By mixing diamond microparticles with an excess of coupling agent, stirring the premix, allowing it to stand, separating the layers, and separating the excess coupling agent in the upper layer to obtain a second mixture, the diamond microparticles can be uniformly and fully coupled. This facilitates the firm adhesion of the diamond microparticles to the bonding surfaces of the connected parts, resulting in a lower viscosity of the diamond microparticle coating liquid, a thinner coating, and greater exposure of the diamond microparticles to the coating surface. This makes it easier for the diamond microparticles to embed into the connected parts, increasing the coefficient of friction between the first and second connected parts and reducing sliding wear.

[0027] In some embodiments, mixing the first mixture with the second mixture to obtain the diamond microparticle coating solution includes:

[0028] The first mixture is mixed with the second mixture to obtain the third mixture;

[0029] The third mixture is mixed with the colorant to obtain a diamond microparticle coating solution.

[0030] Adding a colorant to the diamond microparticle coating solution makes the resulting coating easier to identify and determine if the coating is complete. Adding the colorant last avoids interference from previous coloring processes, ensuring the film color is the desired shade.

[0031] Thirdly, this application provides a connecting assembly, including a first connected member and a second connected member, wherein the first connected member has a first contact surface, the second connected member has a second contact surface, the first contact surface and the second contact surface form an abutment, and a coating is provided on the first contact surface and / or the second contact surface, the coating being formed by the diamond microparticle coating liquid described in the first aspect. Since the diamond microparticles are exposed outside the coating, it is usually sufficient to form a coating on only the first or second contact surface to increase friction and reduce costs. Under certain special working conditions, coatings can also be provided on both the first and second contact surfaces to further increase friction and reduce sliding wear. Typically, after the coating is formed, applying a large axial force through the connecting bolts can cause the exposed diamond microparticles in the coating to embed into the connected member, thereby increasing the coefficient of friction. The diamond microparticle coating liquid coating is used for various connected member mating surfaces, including different surface conditions and different shape profiles. It can be pre-coated for mass-produced connected members or applied on-site for maintenance scenarios, without limiting the application scenario.

[0032] In some embodiments, the coating film thickness is 0.3–10 μm, with diamond exposed in the coating film. Adding a coupling agent to the diamond microparticle coating solution gives the diamond microparticles strong bonding properties, enabling them to form a tight bond with the connecting surfaces when applied. This eliminates the need for high-viscosity adhesives and thick coatings, preventing the diamond microparticles from being encapsulated within the coating. This allows the fully exposed diamond microparticles to embed within the connected components. A minimum coating film thickness of only 0.3 μm is required to achieve reliable adhesion and full exposure of the diamond microparticles, resulting in a better effect on increasing the coefficient of friction. It should be noted that the coating can be formed by partial dip coating, spraying, or brushing, selected according to the shapes of the first and second contact surfaces; these methods will not be elaborated upon here. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the connection surface of the bolted connection structure in the prior art of this application.

[0035] Figure 2 This is a schematic diagram illustrating sliding wear between the mating surfaces of the connected parts in the bolted connection structure of the prior art of this application.

[0036] Figure 3 This is a schematic diagram of the connection component in Embodiment 4 of this application.

[0037] Figure 4 This is an enlarged view of the diamond microparticle coating liquid on the bonding surface of Embodiment 4 of this application.

[0038] Figure 5 This is a schematic diagram of the connection component in Embodiment 5 of this application.

[0039] Figure 6 This is a schematic diagram of the connection component in Embodiment 6 of this application. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0041] Bolted connections are widely used in automobiles and various mechanical structures. A typical bolted connection is as follows: Figure 1 As shown, it consists of a bolt, a nut, and two or more connected parts. There is a mating surface between the two connected parts. Loosening is a common failure mode of bolted connections. Typical causes of bolted connection loosening include: (1) the bolt and nut rotating in the loosening direction due to severe vibration; (2) the mating surface of the connected parts experiencing sliding and wear failures due to insufficient sliding resistance. In response to bolts and nuts rotating loose due to vibration, various types of anti-loosening nuts, anti-loosening bolts, and anti-loosening washers are available on the market, such as non-metallic insert locking nuts, metallic insert locking nuts, locally deformed interference locking nuts, wedge-shaped thread nuts, eccentric double nuts, glued bolts, end-face toothed bolts, sawtooth washers, spring washers, conical elastic washers, double-layered locking washers, etc. However, since these special fasteners are mainly designed for bolts and nuts to rotate loose due to vibration, they can only solve some bolted connection loosening problems.

[0042] Sliding wear between the mating surfaces of the connector and the connected parts, which can further develop into bolt loosening and breakage, is also a common phenomenon in connection failures, especially when the connection structure is subjected to large external loads, such as... Figure 2As shown, since an effective torque type all-metal lock nut has been used, there are no signs of loosening between the nut and the bolt, or between the nut and the connected parts. However, obvious sliding wear has appeared between the two connected parts. This sliding wear has already caused damage to the paint film of the connected parts, resulting in localized corrosion. If it continues to develop, the combined effect of high dynamic tensile stress and fretting wear will lead to fretting fatigue cracking of the connected parts, or fatigue fracture of the bolt due to abnormal dynamic stress, and other serious consequences.

[0043] To prevent slippage at the mating surfaces of the connected parts, on the one hand, the mating surface pressure under service conditions can be increased by increasing the bolt size, increasing the number of bolts, applying a larger initial bolt preload, and controlling the attenuation factor of the bolt axial force. On the other hand, it is necessary to increase the apparent friction coefficient of the mating surfaces of the connected parts.

[0044] The reference friction coefficient distribution range for uncoated machined surfaces is quite wide, ranging from a minimum of 0.04 to a maximum of 0.52. Specifically, the reference friction coefficient for dry, unlubricated steel-aluminum machined mating surfaces ranges from 0.07 to 0.28, with the maximum value being four times the minimum, exhibiting a very wide distribution range. In practical applications, for rust prevention and other requirements, various metallic or non-metallic coatings, such as electroplating, paint, rust-preventive oil, and lubricating oil, are applied to the surface of parts, further increasing the range of friction coefficient distribution at the mating surfaces, with a lower lower limit and a higher upper limit.

[0045] To improve the coefficient of friction at the mating surfaces of connected parts, measures such as controlling the surface conditions of the parts, including applying adhesives, shot peening, or knurling, can be used to achieve a higher and more stable coefficient of friction. However, these measures may have limited effectiveness or conflict with other requirements.

[0046] For example, in one fastening structure, hard particles such as silicon carbide and diamond are introduced into the mating surfaces of the connected parts. These hard particles embed into the surface of the connected parts under the clamping force of the tightening bolts, thereby achieving a higher coefficient of friction. To address the adhesion problem of these hard particles to the mating surfaces of the connected parts, this patent proposes that "the abrasive retaining layer is formed by applying an abrasive-containing anti-rust wax," or "the abrasive retaining layer is made of a metal washer and abrasive particles attached to the two surfaces of the metal washer by an adhesive." However, the anti-rust wax coating itself is relatively thick, requiring larger diamond particle sizes to ensure sufficient tip protrusion. This leads to increased coating costs and significantly impacts the dimensional accuracy of the original structure. Since the primary function of the anti-rust wax is rust prevention, its adhesion to the metal components and diamond surface needs to be improved. Furthermore, the anti-rust wax itself may reduce the coefficient of friction at the mating surfaces.

[0047] A method for producing diamond chemically coated automotive friction pads involves chemically coating a Ni-P-micron diamond layer onto a thin spring steel pad, followed by heat treatment at 150℃ to 350℃. A two-step coating process is employed: first, a Ni-P layer is coated onto the steel pad; second, a Ni-P-micron diamond layer is coated onto the Ni-P layer, with the diamond particles in the coating in a semi-exposed state. In operation, the diamond particles in the coating automatically embed into the opposing surfaces, forming micro-interlocking and increasing friction. However, the friction pad requires a pad material and a nickel-phosphorus coating as a carrier, and both surfaces of the pad need to be coated with the Ni-P-micron diamond coating, increasing application costs. The Ni-P micron diamond plating process is complex and has several specific requirements, such as: pretreatment is crucial for coating quality, ensuring the workpiece surface is free of contamination and in an activated state before plating; acid pickling activation is required; the workpiece needs to be rinsed with hot deionized water; the plating solution needs to be heated; moderate stirring is necessary during plating; and post-plating baking is required. Therefore, this process is costly. A relatively thick nickel-phosphorus plating layer limits the height of the diamond microparticle tip protruding from the plating layer, thus negatively impacting the depth to which the diamond microparticle tip can penetrate the connected components. Adding shims between the connected components alters the original structural dimensional fit, limiting the application range. Shims are poorly adaptable to complex mounting surface contours, limiting rapid application and application scope. Shims introduce new geometric tolerance issues, such as the thickness variation of the shims negatively affecting the overall flatness of a set of mounting bosses, and the cumulative problem of shim geometric tolerances and those of the connected components.

[0048] In view of this, this application provides a diamond microparticle coating liquid, its preparation method and connecting components, to solve the problem of sliding wear between the mating surfaces of existing connectors, which further develops into bolt loosening and breakage.

[0049] In a first aspect, this application provides a diamond microparticle coating liquid, the raw materials of which include:

[0050] Diamond microparticles, dispersants, film-forming agents, corrosion inhibitors, coupling agents, and solvents;

[0051] The coupling agent includes at least one of titanate coupling agents, aluminate coupling agents, and silane coupling agents.

[0052] This application, by adding a coupling agent to the diamond microparticle coating solution, endows the diamond microparticles with strong bonding properties. This allows them to form a tight bond with the connecting parts when coated on the bonding surface, eliminating the need for high-viscosity adhesives and thick coatings. This prevents the diamond microparticles from being encapsulated within the coating, allowing them to be fully exposed and embedded within the connected parts. This reduces sliding wear between the connecting and connected parts, minimizing problems such as bolt loosening and breakage. The diamond microparticle coating solution of this application results in a thin coating, a large exposed area of ​​diamond microparticles, strong adhesion, and a simple process.

[0053] It should be noted that coupling agents containing at least one of titanate, aluminate, or silane coupling agents have the advantage of enhancing the adhesion between diamond and the film layer compared to other types of coupling agents. Furthermore, due to the widespread bonding ability of coupling agents with various materials, the surfaces of the joined parts can be bare metal, anodic protective coatings such as zinc plating, or common paint coatings. Utilizing the chemical bonding mechanism of the coupling agent, a thin but strongly adhesive coupling agent coating layer can be formed on the mounting surface, thus fully exposing the tips of the diamond particles and facilitating their embedding / biting into the joined surface material. Typically, a layer of coupling agent is pre-applied to the joined parts, followed by a diamond particle coating liquid applied to the coupling agent surface to improve the bonding strength between the diamond particles and the connector.

[0054] In conjunction with the first aspect, in some embodiments provided in this application, the mass percentage of the diamond microparticles in the diamond microparticle coating liquid is 10% to 30%. Within this range, the area percentage of the diamond microparticles in the diamond microparticle coating liquid can reach 10% to 80% after the coating is formed, thereby increasing the friction between the two connected parts and reducing the sliding wear between the two connected parts.

[0055] In conjunction with the first aspect, in some embodiments provided in this application, the coupling agent accounts for 3% to 5% of the mass of the diamond microparticle coating liquid. Within this range, the coupling agent can improve the bonding strength between the diamond microparticles and the connector, further reduce the coating thickness, expose and protrude the diamond microparticles from the surface of the coating, and make it easier for them to embed into the connected parts, thereby increasing the friction coefficient between the two connected parts and reducing sliding wear.

[0056] In conjunction with the first aspect, in some embodiments provided in this application, the particle size of the diamond microparticles is 5 to 60 μm. The particle size of the diamond microparticles within this range makes them more easily exposed on the coating surface, making it easier for the diamond microparticles to embed into the connected parts, thereby increasing the coefficient of friction between the two connected parts and reducing sliding wear.

[0057] In conjunction with the first aspect, in some embodiments provided in this application, the mass ratio of the dispersant, film-forming agent, corrosion inhibitor, and solvent is (10-25):(28-40):(0.5-1):(30.6-36). This mass ratio allows for a lower viscosity of the diamond microparticle coating solution, resulting in a thinner coating. This facilitates the exposure of diamond microparticles to the coating surface, making it easier for the diamond microparticles to embed into the joined parts, increasing the coefficient of friction between the two joined parts, and reducing sliding wear. It should be noted that the addition of a coupling agent prevents the amount of film-forming agent from becoming excessive, thus controlling the coating thickness.

[0058] In conjunction with the first aspect, in some embodiments provided in this application, the dispersant includes at least one of sodium petroleum sulfonate, sodium oleate, and sodium phthalate. Using at least one of the above dispersants can fully disperse various components and enhance the dispersion performance of diamond during the stirring process.

[0059] In conjunction with the first aspect, in some embodiments provided in this application, the film-forming agent includes at least one of monoglyceride fatty acid ester and propylene glycol methyl ether acetate. By using at least one of the above film-forming agents, a thin and dense film layer can be formed on the surface of the part.

[0060] In conjunction with the first aspect, in some embodiments provided in this application, the corrosion inhibitor includes at least one of benzotriazole, phosphonic acid, and mercaptobenzothiazole. Using at least one of the above corrosion inhibitors can reduce the erosion of the part surface and improve the rust prevention performance when coated on the bare surface of the part.

[0061] In conjunction with the first aspect, in some embodiments provided in this application, the solvent includes at least one of polyalphaolefin synthetic oil, carboxylic acid ester synthetic oil, and ester synthetic oil. Using at least one of the above solvents can provide a stable dispersion environment and rapid drying performance.

[0062] In conjunction with the first aspect, in some embodiments provided in this application, the raw materials also include colorants. Dispersants, film-forming agents, corrosion inhibitors, and solvents are typically transparent and colorless, making it difficult to see whether the coating is complete and to observe the coating area during coating. Therefore, colorants can be added to the diamond microparticle coating solution to make the coating easier to identify and determine whether the coating is complete. Bright colors, such as yellow, red, blue, green, purple, and orange, can be used. To reduce the impact of the colorant on the entire diamond microparticle coating solution system, azo-type colorants can be selected. The mass percentage of the colorant in the entire diamond microparticle coating solution can be 0.3% to 0.5%.

[0063] Secondly, this application provides a method for preparing a diamond microparticle coating liquid, comprising the following steps:

[0064] The dispersant, film-forming agent, corrosion inhibitor, and solvent are mixed to obtain the first mixture;

[0065] Diamond microparticles are mixed with a coupling agent to obtain a second mixture;

[0066] The first mixture and the second mixture are mixed to obtain a diamond microparticle coating solution.

[0067] By mixing diamond microparticles with a coupling agent to obtain a second mixture, the diamond microparticles can be fully coupled, which is beneficial for the diamond microparticles to adhere firmly to the bonding surface of the connected parts. This allows the viscosity of the diamond microparticle coating liquid to be lower, the coating thickness to be thinner, and the diamond microparticles to be more exposed on the surface of the coating. This makes it easier for the diamond microparticles to embed into the connected parts, increasing the coefficient of friction between the two connected parts and reducing sliding wear.

[0068] In conjunction with the second aspect, in some embodiments provided in this application, the mixing of diamond microparticles with a coupling agent to obtain a second mixture includes:

[0069] Diamond microparticles are mixed with an excess of coupling agent to obtain a premixed solution;

[0070] Stir the premixed solution, let it stand, separate the layers, and separate the excess coupling agent in the upper layer to obtain the second mixture.

[0071] By mixing diamond microparticles with an excess of coupling agent, stirring the premix, allowing it to stand, separating the layers, and separating the excess coupling agent from the upper layer to obtain a second mixture, the diamond microparticles can be uniformly and fully coupled. This facilitates the firm adhesion of the diamond microparticles to the bonding surfaces of the connected parts, resulting in a lower viscosity of the diamond microparticle coating solution, a thinner coating, and greater exposure of the diamond microparticles to the coating surface. This makes it easier for the diamond microparticles to embed into the connected parts, increasing the coefficient of friction between the two connected parts and reducing sliding wear.

[0072] In conjunction with the second aspect, in some embodiments provided in this application, the mixing of the first mixture and the second mixture to obtain the diamond microparticle coating liquid includes:

[0073] The first mixture is mixed with the second mixture to obtain the third mixture;

[0074] The third mixture is mixed with the colorant to obtain a diamond microparticle coating solution.

[0075] Adding a colorant to the diamond microparticle coating solution makes the resulting coating easier to identify and determine if the coating is complete. Adding the colorant last avoids interference from previous additions, ensuring the film color is the desired. Specifically, stirring at 1000–2000 rpm for 15–30 minutes allows for thorough coupling of the diamond microparticles.

[0076] Thirdly, this application provides a connecting assembly, including a first connected member and a second connected member, wherein the first connected member has a first contact surface, the second connected member has a second contact surface, the first contact surface and the second contact surface form an abutment, and a coating is provided on the first contact surface and / or the second contact surface, the coating being formed by the diamond microparticle coating liquid described in the first aspect. Since the diamond microparticles are exposed outside the coating, it is usually sufficient to form a coating on only the first or second contact surface to increase friction and reduce costs. Under certain special working conditions, coatings can also be provided on both the first and second contact surfaces to further increase friction and reduce sliding wear. Typically, after the coating is formed, applying a large axial force through the connecting bolts can cause the exposed diamond microparticles in the coating to embed into the connected member, thereby increasing the coefficient of friction. The diamond microparticle coating liquid coating is used for various connected member mating surfaces, including different surface conditions and different shape profiles. It can be pre-coated for mass-produced connected members or applied on-site for maintenance scenarios, without limiting the application scenario.

[0077] It should be noted that since the diamond microparticle coating solution is not a stable and homogeneous system, it is necessary to continuously stir the diamond microparticle coating solution during coating in order to improve the uniformity of the coating, for example, by stirring at a stirring speed of 200 rpm, so as to achieve the uniformity of the entire suspension system.

[0078] In conjunction with the third aspect, in some embodiments provided in this application, the thickness of the coating film is 0.3–10 μm, wherein the diamond is exposed in the coating film. Adding a coupling agent to the diamond microparticle coating solution gives the diamond microparticles strong bonding properties, enabling them to form a tight bond with the connecting parts when applied to the connecting surfaces. This eliminates the need for high-viscosity adhesives and thick coatings, preventing the diamond microparticles from being encapsulated within the coating. This allows the fully exposed diamond microparticles to embed within the connected parts. A minimum coating film thickness of only 0.3 μm is required to achieve reliable adhesion and full exposure of the diamond microparticles, resulting in a better effect in increasing the coefficient of friction. It should be noted that the coating can be formed by partial dip coating, spraying, or brushing, selected according to the shapes of the first and second contact surfaces; these methods will not be elaborated upon here.

[0079] The technical solutions provided in this application will be described in detail below with reference to the embodiments and accompanying drawings.

[0080] Example 1

[0081] Example 1 of this application provides a diamond microparticle coating liquid, comprising the following raw materials:

[0082] Diamond microparticles, sodium petroleum sulfonate, monoglyceride fatty acid esters, benzotriazole, polyalphaolefin synthetic oil, and titanate coupling agent, wherein:

[0083] The diamond microparticles have a particle size of 25 μm and the mass percentage of diamond microparticles in the diamond microparticle coating solution is 10%.

[0084] The mass ratio of sodium petroleum sulfonate, monoglyceride fatty acid ester, benzotriazole, and dodecenylsuccinic acid is 10:28:0.5:30.6.

[0085] The titanate coupling agent accounts for 3% of the mass of the diamond microparticle coating solution.

[0086] Example 2

[0087] Example 2 of this application provides a diamond microparticle coating liquid, comprising the following raw materials:

[0088] Diamond microparticles, sodium petroleum sulfonate, propylene glycol methyl ether acetate, benzotriazole, synthetic oils of carboxylic acid esters, and titanate coupling agents, wherein:

[0089] The diamond microparticles have a particle size of 45 μm and the mass percentage of diamond microparticles in the diamond microparticle coating solution is 20%.

[0090] The mass ratio of sodium petroleum sulfonate, propylene glycol methyl ether acetate, benzotriazole, and carboxylic acid ester synthetic oil is 20:35:0.8:35.

[0091] The coupling agent accounts for 4% of the mass of the diamond microparticle coating solution.

[0092] Example 3

[0093] Example 3 of this application provides a diamond microparticle coating liquid, comprising the following raw materials:

[0094] Diamond microparticles, sodium phthalate, monoglyceride fatty acid esters, phosphonic acid carboxylic acids, synthetic oils of esters, and aluminate coupling agents, wherein:

[0095] The diamond microparticles have a particle size of 60 μm and the mass percentage of diamond microparticles in the diamond microparticle coating solution is 30%.

[0096] The mass ratio of sodium phthalate, monoglyceride fatty acid ester, phosphonic acid, and ester synthetic oil is 25:40:1:36.

[0097] The coupling agent accounts for 5% of the mass of the diamond microparticle coating solution.

[0098] Example 4

[0099] Embodiment 4 of this application provides a connecting assembly, a bolt connection assembly between the inner ring of a pulley bearing and a support. Due to the large lateral load on the connecting mating surface, slippage occurs, leading to bolt loosening and breakage, resulting in connection failure. A diamond microparticle friction-enhancing layer is coated on its mounting mating surface. For example... Figure 3 As shown, the pulley is radially connected to the outer ring of the bearing via an interference fit, and the inner ring of the bearing is connected to the pulley mounting bracket via bolts. The initial slippage occurs at the mating surface between the inner ring of the bearing and the bracket, i.e., the mating surface of the connected parts. The material of the first connected part, the inner ring of the bearing, is GCr15, with a heat treatment hardness of approximately 60 HRC. Its mating surface is ground to a roughness of Ra0.4, with no other coating. The material of the second connected part, the bracket, is ductile iron QT500, with a hardness of approximately 200 HB. Its mating surface is turned to a roughness of Ra1.6-Ra3.2, with no other coating. The coefficient of friction between the mating surfaces of the two connected parts is 0.10-0.23 (minimum 0.10). Using the diamond microparticle coating liquid of Example 1, a diamond microparticle friction-enhancing layer is coated on the mating surface of the inner ring of the first connected part, such as... Figure 4As shown, the thickness of the continuous coating layer is approximately 5 μm, and the thickness of the diamond microparticle dispersion layer embedded in the continuous coating layer with its tips exposed above it is approximately 25 μm. The M16-12.9 grade bolts used in the connecting structure are tightened to the yield point using the torque-angle method, and the diamond microparticles are embedded in the end faces of the inner ring of the bearing and the support of the connected components. The minimum friction coefficient of the mating surface is increased from ≥0.1 to ≥0.35, significantly improving the safety factor against lateral slippage of the mating surface.

[0100] Example 5

[0101] Embodiment 5 of this application provides a connecting assembly in which a pin is connected to a support bolt. The pin at the end of the support beam, connected to the support bolt, bears a large lateral load. Slippage at the connection surface leads to severe wear of the support and bolt breakage, resulting in connection failure. Therefore, a diamond microparticle friction-enhancing layer is coated on its mounting surface. For example... Figure 5 As shown, the pin is connected to the end support of the support beam via bolts and nuts. The initial slippage occurs at the mating surface between the pin and the support, i.e., the mating surface of the connected parts. The pin is made of 40Cr with a heat treatment hardness of approximately 40HRC. Its mating surface is sandblasted to a roughness of Ra3.2-Ra6.3, and the outer surface is covered with a phosphate layer approximately 2 micrometers thick. The support is made of ductile iron QT600 with a hardness of approximately 230HB. Its mating surface is milled to a roughness of Ra3.2-Ra6.3, and the outer surface is covered with an electrophoretic paint layer approximately 25 micrometers thick. The coefficient of friction between the mating surfaces of the two connected parts is 0.15-0.25. The diamond microparticle coating liquid of Example 2 is applied to the mounting surface of the connected pin, with a coating film thickness of approximately 6 μm. A diamond microparticle dispersion layer, approximately 45 μm thick, is embedded in the continuous coating film with its tips exposed above it. The M20-10.9 grade bolts used in the connection structure are tightened to an axial preload ≥109 kN. The diamond microparticles are embedded in the mounting surfaces of both the connector-pin and the connected component-support. The minimum coefficient of friction at the joint surfaces is increased from ≥0.15 to ≥0.40, significantly improving the safety factor against lateral slippage.

[0102] Example 6

[0103] Embodiment 6 of this application provides a connecting assembly in which a large bracket is bolted to a longitudinal beam of the vehicle frame. The bolted connection between the large bracket and the longitudinal beam bears a large lateral load, and slippage at the connection surface leads to paint film wear and bolt loosening, resulting in connection failure. Therefore, a diamond microparticle friction-enhancing layer is coated on its mounting surface. Figure 6As shown, the large bracket is connected to the longitudinal beam of the vehicle frame via bolts and nuts. The initial slippage occurs at the joint surface between the large bracket and the longitudinal beam, i.e., the joint surface of the connected components. The large bracket is made of ductile iron QT600 with a hardness of approximately 230HB. Its mounting surface is milled to a roughness of Ra3.2-Ra6.3, and its outer surface is covered with an electrophoretic paint layer approximately 25 micrometers thick. The longitudinal beam is made of steel plate for the main beam with a hardness of approximately 220HB. Its surface is cold-rolled and powder-coated, with a powder coating thickness of approximately 100μm. The coefficient of friction between the two joint surfaces is 0.05-0.10. The diamond microparticle coating liquid of Example 3 is applied to the mounting surface of the main support of the connected component. The thickness of the coating film is approximately 9 μm. The thickness of the diamond microparticle dispersion layer, embedded in the continuous coating film with its tips exposed above the continuous coating film, is approximately 60 μm. The M18-10.9 grade bolts used in the connecting structure are tightened to an axial preload ≥85 kN. The diamond microparticles are embedded in the mounting surface of the connector-main support and the mounting surface of the connected component-vehicle frame longitudinal beam. The minimum friction coefficient of the joint surface is increased from ≥0.05 to ≥0.25, and the safety factor against lateral slippage of the joint surface is significantly improved.

[0104] Comparative Example 1

[0105] The same diamond microparticles as in Example 1 of this application are used, with a particle size of about 25 μm, and the mass ratio of diamond microparticles in the diamond microparticle coating solution is 10%. The difference is that the diamond microparticles in Comparative Example 1 are dispersed in rust-preventive wax by stirring, without coupling agent (SP-WAX-160 type rust-preventive wax, produced by Shenyang Pakase Sei Co., Ltd.) to form diamond microparticle coating solution.

[0106] Comparative Example 2

[0107] Comparative Example 2 of this application provides a connecting assembly, a bolted connection assembly between the inner ring of a pulley bearing and its support. Due to the large lateral load on the connecting mating surface, slippage occurs, leading to bolt loosening and breakage, resulting in connection failure. A diamond microparticle friction-enhancing layer is coated on the mounting mating surface. The pulley is radially connected to the outer ring of the bearing via an interference fit, and the inner ring of the bearing is bolted to the pulley mounting support. The initial slippage occurs at the connecting mating surface between the inner ring of the bearing and the support, i.e., the mating surface of the connected parts. The first connected part, the inner ring of the bearing, is made of GCr15 with a heat-treated hardness of approximately 60 HRC. Its mounting mating surface is ground to a roughness of Ra0.4 and has no other coating. The second connected part, the support, is made of ductile iron QT500 with a hardness of approximately 200 HB. Its mounting mating surface is turned to a roughness of Ra1.6-Ra3.2 and has no other coating. The coefficient of friction between the mounting mating surfaces of the first and second connected parts is 0.10-0.23 (minimum 0.10). Using the diamond microparticle coating liquid of Comparative Example 1, a diamond microparticle coating liquid was sprayed onto the mating surface of the inner ring of the bearing in the connecting component. The thickness of the continuous coating layer was approximately 30 μm. The M16-12.9 grade bolts used in the connecting structure were tightened to the yield point using the torque-angle method. The coefficient of friction of the mating surface was 0.12-0.20. The film thickness formed by the coating liquid of Comparative Example 1 was approximately 30 μm, and the diamond microparticles had a particle size of approximately 25 μm. Since the diamond microparticles were not exposed, it did not produce a significant improvement in the coefficient of friction.

[0108] In summary, by adding a coupling agent to the diamond microparticle coating solution, the diamond microparticles acquire strong coupling properties, enabling them to form a tight bond with the connectors when applied to the joint surface. This eliminates the need for high-viscosity adhesives and thick coatings, allowing the diamond microparticles to be fully exposed and embedded within the connected components. This reduces sliding wear between the connectors and the connected components, and minimizes problems such as bolt loosening and breakage.

[0109] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0110] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly specified.

[0111] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A diamond microparticle coating fluid, characterized by, The raw materials include: diamond microparticles, a dispersing agent, a film forming agent, an inhibitor, a coupling agent, and a solvent; The coupling agent includes at least one of a titanate coupling agent, an aluminate coupling agent, and a silane coupling agent; The mass ratio of the diamond microparticles in the diamond microparticle coating liquid is 10-30%; The mass ratio of the coupling agent in the diamond microparticle coating liquid is 3-5%; The particle size of the diamond microparticles is 5-60 μm.

2. The diamond microparticle coating fluid of claim 1, wherein, The mass ratio of the dispersing agent, the film forming agent, the inhibitor, and the solvent is (10-25):(28-40):(0.5-1):(30.6-36).

3. The diamond microparticle coating liquid of claim 1, wherein: The dispersing agent includes at least one of sodium petroleum sulfonate, sodium oleate, and sodium phthalate; and / or, The film forming agent includes at least one of monoglyceride fatty acid ester and propylene glycol methyl ether acetate; and / or, The inhibitor includes at least one of benzotriazole, phosphine carboxylic acid, and mercaptobenzothiazole; and / or, The solvent includes at least one of poly-alpha olefin synthetic oil, carboxylic acid ester synthetic oil, and ester synthetic oil.

4. The diamond microparticle coating fluid of claim 1, wherein, The raw materials further include a colorant.

5. A method for producing the diamond fine particle coating liquid according to any one of claims 1 to 4, characterized by, The method includes the following steps: mixing the dispersing agent, the film forming agent, the inhibitor, and the solvent to obtain a first mixed liquid; mixing the diamond microparticles and the coupling agent to obtain a second mixed liquid; mixing the first mixed liquid and the second mixed liquid to obtain the diamond microparticle coating liquid.

6. The method for preparing the diamond microparticle coating liquid as described in claim 5, characterized in that, The mixing of the diamond microparticles and the coupling agent to obtain the second mixed liquid includes: mixing the diamond microparticles and excess coupling agent to obtain a premix liquid; stirring the premix liquid, standing, layering, and separating the excess coupling agent in the upper layer to obtain the second mixed liquid.

7. The method for preparing the diamond microparticle coating liquid as described in claim 5, characterized in that, The mixing of the first mixed liquid and the second mixed liquid to obtain the diamond microparticle coating liquid includes: mixing the first mixed liquid and the second mixed liquid to obtain a third mixed liquid; mixing the third mixed liquid and the colorant to obtain the diamond microparticle coating liquid.

8. A connection assembly characterized in that, The device includes a first connector and a second connector, wherein the first connector has a first contact surface, the second connector has a second contact surface, the first contact surface and the second contact surface abut, and a coating layer is provided on the first contact surface and / or the second contact surface, the coating layer being coated by the diamond microparticle coating liquid according to any one of claims 1-4.

9. The connection assembly of claim 8, wherein, The thickness of the coating film layer of the coating layer is 0.3-10 μm, and the diamond is exposed to the coating film layer.

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