阅读说明：本技术 用于部件的摩擦增加连接的连接元件、用于制备连接元件的方法以及连接元件的用途 (Connecting element for friction-increasing connection of components, method for producing a connecting element, and use of a connecting element ) 是由 多米尼克·道布 弗洛里安·T·格林 于 2020-05-21 设计创作，主要内容包括：本公开涉及一种连接元件和一种用于制造该连接元件的方法。本公开还涉及该连接元件的用途,用于在机器、设备和机动车辆结构以及能量产生中连接待接合的第一部件和第二部件。(The present disclosure relates to a connecting element and a method for manufacturing the connecting element. The disclosure also relates to the use of the connecting element for connecting a first component and a second component to be joined in machines, devices and motor vehicle structures and energy generation.)

1. A connecting element comprising a metal substrate (1) having a first joint surface (2) on one side of the substrate and a second joint surface (3) on the opposite side of the substrate, wherein each joint surface (2,3) comprises hard particles (4) fixed to the metal substrate (1) by a binder layer (5), and wherein the binder layer comprises a polymer material.

2. The connecting element of claim 1, wherein the polymeric material is selected from the group consisting of: epoxy materials, acrylic materials, polyester materials, polyurethane materials, formaldehyde resins, polyvinyl acetate (PVAC) materials, polyvinyl chloride (PVC) materials, alkyd resins, silicone materials, rubber materials, fluoropolymers, and combinations thereof.

3. Connecting element according to claim 1 or 2, wherein the hard particles (4) are selected from the group consisting of: carbides, borides, nitrides, silica, alumina, diamond, and mixtures thereof.

4. Connecting element according to any of claims 1 to 3, wherein the hard particles (4) have an average particle size (d)₅₀) Is 5 μm to 120 μm.

5. The connecting element according to any one of claims 1 to 4, wherein the metal substrate (1) comprises steel.

6. The connecting element according to any one of claims 1 to 5, wherein the connecting element does not comprise a metal binder layer for fixing the hard particles on the metal substrate.

7. The connecting element according to any one of claims 1 to 6, wherein the area percentage of the first and second joining surfaces (2,3) of the metal base material (1) covered with hard particles (4) is 5% to 80%.

8. Connecting element according to any of claims 1 to 7, wherein the adhesive layer (5) has a thickness of 2 to 100 μm.

9. Connecting element according to any of claims 1 to 8, wherein the hard particles (4) protrude from the binder layer by the average particle size (d) of the hard particles₅₀) Up to 95% of the total weight of the composition.

10. Connecting element according to any of claims 1 to 9, wherein the hard particles (4) protrude from the binder layer by the average particle size (d) of the hard particles₅₀) At least 5% of the total weight of the composition.

11. A method for manufacturing a connecting element according to any one of claims 1 to 10, the method comprising

Providing a metal substrate (1) having a first bonding surface (2) on one side of the substrate and a second bonding surface (3) on the opposite side of the substrate,

providing hard particles (4), and

-fixing the hard particles (4) on the first and second joint surfaces (2,3) with a binder layer (5), wherein the binder layer comprises a polymer material.

12. The method according to claim 11, wherein the step of fixing the hard particles (4) on the first and second joint surfaces (2,3) with a binder layer comprises

Fixing the hard particles (4) on the first and second joint surfaces (2,3) with a first layer of a polymeric binder layer, wherein the thickness of the first layer is the average particle size (d) of the hard particles₅₀) At least 5% of, and

embedding the hard particles (4) on the first and second joint surfaces (2,3) with a second layer of a polymeric binder layer, wherein the thickness of the second layer is the average particle size (d) of the hard particles₅₀) At least 5% of the total weight of the composition.

13. A method for frictionally coupling a first component and a second component, the method comprising:

providing a connecting element according to any one of claims 1 to 11;

providing a first component having a component engagement surface and a second component having a component engagement surface,

pressing hard particles (4) of a first joint surface (2) of the connecting element into a component joint surface of the first component, and

pressing hard particles (4) of a second joint surface (3) of the connecting element into a component joint surface of the second component,

thereby frictionally coupling the first and second components with the connecting element.

14. A friction joint comprising a first component having a component engagement surface, a second component having a component engagement surface, and a connecting element according to any one of claims 1 to 11, wherein the first component and the second component are in frictional engagement with the connecting element.

15. Use of a connecting element according to any one of claims 1 to 11 for connecting a first component and a second component to be joined in machines, devices and motor vehicle construction and energy production.

Technical Field

The present disclosure relates to a connecting element for a friction increasing connection of parts to be joined.

Background

Force-locked (force-locked) connections are often used to transmit forces or torques in all areas of machinery, equipment and motor vehicle construction and energy production. The amount of force that can be transmitted depends not only on the structural design but also primarily on the static friction value (coefficient of static friction) of the surfaces of the components that are connected to one another. With such force-locking connections, therefore, efforts are made to provide friction-increasing measures which allow the greatest possible lateral forces and torques to be transmitted safely. Additionally, force-locking connections may also be referred to as non-positive connections or friction connections.

It is known to use friction increasing interlayers to increase the holding force or increase the torque that can be transmitted in the bolt connection and the clamp connection. US 6,347,905B 1 discloses a connecting element for a friction increasing, play-free reversible connection of parts to be joined. The connecting element comprises a spring-loaded elastic steel foil having particles of a defined size on its surface, which particles are fixed to the spring-loaded elastic foil by means of a metal binder phase. The particles consist of a hard material, preferably diamond, cubic boron nitride, aluminum oxide, silicon carbide or boron carbide. The metallic binder phase is preferably nickel. By using such a separate connecting element, the static friction coefficient in the friction connection can be increased.

The hard particles fixed to the spring-elastic foil by means of a metallic binder phase are coated on the spring-elastic foil by means of an electroplating process, preferably by means of an electroless coating process. This process is time consuming and expensive.

For many bolted or clamped connections, it is desirable to prevent corrosion of the parts to be joined. This is particularly desirable if the vehicle or machine is used in a corrosive environment, or if the bolted parts are composed of different materials (e.g., carbon steel and aluminum). These connections need to be protected from fretting or electrochemical corrosion and the surfaces of the parts to be joined should not be damaged to allow reversible connection of the parts.

Therefore, further improvement in the frictional connection of the parts in terms of corrosion resistance is required. Furthermore, there is a need to provide a connecting element for a friction increasing connection of parts to be joined, which connecting element can be prepared by a less time consuming and more economical process.

Disclosure of Invention

In a first aspect, the present disclosure relates to a connecting element comprising a metal substrate having a first bonding surface on one side of the substrate and a second bonding surface on an opposite side of the substrate, wherein each bonding surface comprises hard particles fixed to the metal substrate by a binder layer, and wherein the binder layer comprises a polymeric material.

In another aspect, the present disclosure also relates to a method for manufacturing such a connecting element, the method comprising:

providing a metal substrate having a first bonding surface on one side of the substrate and a second bonding surface on an opposite side of the substrate,

the provision of hard particles which are,

the hard particles are secured to the first and second bonding surfaces with an adhesive layer, wherein the adhesive layer comprises a polymeric material.

In yet another aspect, the present disclosure is directed to a method for frictionally coupling a first component and a second component, the method comprising:

there is provided a connecting element as disclosed herein,

providing a first component having a component engagement surface and a second component having a component engagement surface,

pressing the hard particles of the first engagement surface of the connecting element into the component engagement surface of the first component,

pressing the hard particles of the second joint surface of the connecting element into the component joint surface of the second part,

thereby frictionally coupling the first and second components with the connecting element.

In yet another aspect, the present disclosure is also directed to a friction joint comprising a first component having a component engagement surface, a second component having a component engagement surface, and a connecting element as disclosed herein, wherein the first component and the second component are frictionally engaged with the connecting element.

In a further aspect, the present disclosure also relates to the use of such a connecting element for connecting a first component and a second component to be joined in machines, devices and motor vehicle structures and energy generation.

In some embodiments, the connection element according to the present disclosure is significantly less susceptible to corrosion than the connection element disclosed in US 6,347,905B 1. In particular, the connection element according to the present disclosure is significantly less susceptible to corrosion with respect to moisture, water or any other humid environment.

The connecting element according to the present disclosure can be prepared by an economical process. The connecting elements disclosed herein can be prepared by a process that is less time consuming than the preparation process of the connecting elements disclosed in US 6,347,905B 1.

In some embodiments, a connecting element according to the present disclosure is suitable for frictional connections where electrochemical corrosion and fretting are issues.

By using the connecting element according to the present disclosure, the static friction coefficient of the frictional connection is increased.

Drawings

The disclosure is explained in more detail on the basis of the drawings, in which

Fig. 1 schematically shows a cross-sectional view of a connecting element of the present disclosure.

Detailed Description

The hard particles are preferably composed of a material that does not chemically react with the materials of the parts to be joined or with the ambient medium under the particular conditions of use. The material is preferably an inorganic material.

The hard particles may be selected from the group consisting of: carbides, borides, nitrides, silica, alumina, diamond, and mixtures thereof. Examples of carbides are silicon carbide, tungsten carbide and boron carbide; examples of nitrides are silicon nitride and cubic boron nitride. Preferably, diamond is used as the hard particles.

The size of the hard particles is chosen such that a sufficient number of particles will interact with the joining surface of the parts to be joined by being pressed into the surface. Preferably, this is ensured if the grain size is greater than twice the peak-to-valley height of the engaging surface, wherein the peak-to-valley results from machining of the engaging surface. Average particle size (d) of 120 μm or less₅₀) This requirement is usually met. The hard particles may have an average particle size (d) of 5 to 120 μm₅₀). In some embodiments, the hard particles may have an average particle size (d) of 5 μm to 60 μm, or 5 μm to 40 μm, or 20 μm to 60 μm, or 35 μm to 60 μm₅₀). The average particle size can be measured by laser diffraction (e.g., Mastersizer, wet dispersion).

The hard particles should have a narrow particle size range with a dispersion of no more than about +/-50% about a given nominal diameter. In some embodiments, the dispersion around a given nominal diameter should not exceed about +/-25%.

The hard particles are fixed to the metal substrate by a binder layer comprising a polymeric material.

A connecting element as disclosed herein comprises a metal substrate having a first bonding surface on one side of the substrate and a second bonding surface on the opposite side of the substrate. Each bonding surface comprises hard particles secured to a metal substrate by an adhesive layer comprising a polymeric material.

In some embodiments, the binder layer is comprised of a polymeric material.

The polymeric material is selected from the group consisting of: epoxy materials, acrylic materials, polyester materials, polyurethane materials, formaldehyde resins, polyvinyl acetate (PVAC) materials, polyvinyl chloride (PVC) materials, alkyd resins, silicone materials, rubber materials, fluoropolymers, and combinations thereof.

In some embodiments, the polymeric material may be an adhesive material. The adhesive properties of the polymer material may be used to pre-assemble the connecting element by gluing it to one of the parts to be joined. By gluing, the connecting element will have its correct position on one of the parts to be joined and will maintain this position during assembly to the second part to be joined. Examples of the adhesive material are rubber-based adhesives, acrylic-based adhesives, and silicone-based adhesives.

In some embodiments, the binder layer comprising the polymeric material may be in the form of a lacquer. Either water-based paints or non-water-based paints may be used.

In some embodiments of the methods disclosed herein, the polymeric material may be in the form of an oil that is hardened after the process of securing the hard particles with the binder layer. Suitable oils are, for example, silicone oils.

The adhesive layer of the connecting elements disclosed herein may also comprise fillers, pigments, and additives. Fillers that can be used in the binder layer can be, for example, fillers for surface structure modification. The pigment that can be used in the binder layer may be, for example, an inorganic or organic color pigment, or a pigment for improving corrosion resistance. Additives that may be used in the binder layer may be, for example, biocides or surfactants.

The connecting element as disclosed herein does not comprise a metallic binder layer for fixing the hard particles to the metal substrate.

The metal substrate may comprise steel. The metal substrate may be made of steel (e.g., non-alloy steel). Low alloy steel, high alloy steel or stainless steel may also be used. Examples of non-alloyed steels are grades C75S-1.1248 according to DIN EN10132-4 or grades C60S-1.1211 according to DIN EN 10132-4. Non-ferrous metals, aluminum alloys, or titanium alloys may also be used.

The adhesive layer of the connecting element disclosed herein has a thickness of 2 μm to 100 μm. In some embodiments, the adhesive layer may have a thickness of 10 μm to 70 μm. In some embodiments, the adhesive layer may have a thickness of 10 μm to 30 μm or 30 μm to 70 μm.

In some embodiments, the thickness of the binder layer is the average particle size (d) of the hard particles₅₀) At least 15% of the total weight of the composition. In some embodiments, the thickness of the binder layer is the average particle size (d) of the hard particles₅₀) At least 20%, or at least 25%, or at least 30%.In some embodiments, the thickness of the binder layer is the average particle size (d) of the hard particles₅₀) At least 40%, or at least 50%, or at least 60%, or at least 70%, or at least 80%.

In some embodiments, the thickness of the binder layer is the average particle size (d) of the hard particles₅₀) At most 30%. In some embodiments, the thickness of the binder layer is the average particle size (d) of the hard particles₅₀) At most 40%, or at most 50%, or at most 60%, or at most 70%, or at most 80%, or at most 90%.

In some embodiments, the thickness of the binder layer is the average particle size (d) of the hard particles₅₀) At least 15% and at most 30%, or the average particle size (d) of the hard particles₅₀) At least 30% and at most 60%. In some embodiments, the thickness of the binder layer is the average particle size (d) of the hard particles₅₀) At least 60% and at most 90%.

The hard particles may protrude the average particle size (d) of the hard particles from the binder layer₅₀) Up to 95% of the total weight of the composition. In some embodiments, the hard particles protrude from the binder layer by the average particle size of the hard particles (d)₅₀) At most 90%, or at most 80%, or at most 70%, or at most 60%.

The hard particles may protrude the average particle size (d) of the hard particles from the binder layer₅₀) At least 5% of the total weight of the composition.

In some embodiments, the hard particles protrude from the binder layer by the average particle size of the hard particles (d)₅₀) At least 10%, at least 15%, or at least 20%, or at least 25%, or at least 30%, or at least 35%, or at least 40%.

The height of the hard particles protruding from the binder layer may be determined by the average particle size (d) of the hard particles₅₀) The thickness of the adhesive layer is subtracted.

The number of hard particles per unit surface area of the joining surfaces of the connecting elements may be selected such that the normal force available to join the parts together is sufficient to ensure that the particles are pressed into the surfaces of the parts to be joined. If the first bonding surface and the second bonding surface of the metal base material are covered with hard coatingThis will typically be the case if the area percentage of the particles is from 5% to 80%. May be based on the average particle size (d) of the hard particles₅₀) The percentage of the area of the bonding surface of the metal base material covered with hard particles is selected. For example, the average particle size (d) for 25 μm hard particles₅₀) About 8% to 30% of the bonding surface of the metal base material may be covered with hard particles for an average particle size (d) of the hard particles of 35 μm₅₀) The area percentage may be about 15% to 60% for an average particle size (d) of 55 μm₅₀) The area percentage may be about 20% to 70%, and for an average particle size (d) of 75 μm₅₀) The area percentage may be about 25% to 80%.

The thickness of the metal substrate is selected according to the application. In some embodiments, the metal substrate has a thickness of at most 2.0 mm. In other embodiments, the thickness is at most 1.0mm or at most 0.5 mm. In some other embodiments, the thickness is at most 0.2 mm. In some other embodiments, the thickness is at most 0.1 mm. For larger connection elements that need to have higher strength and stiffness, such as connection elements for parts of wind turbines, the thickness of the metal substrate may be at most 0.5mm or at most 1.0mm or at most 2.0 mm. For applications requiring thinner connecting elements, the thickness of the metal substrate may be 0.2mm or less, preferably 0.1mm, for example if the design of the parts to be joined should not be changed.

The connecting elements disclosed herein may be annular. The annular connecting element may be a single piece or may be a segmented ring.

The connecting element as disclosed herein may be prepared by a method comprising the steps of:

providing a metal substrate having a first bonding surface on one side of the substrate and a second bonding surface on an opposite side of the substrate,

providing hard particles, and

the hard particles are secured to the first and second bonding surfaces with an adhesive layer, wherein the adhesive layer comprises a polymeric material.

Fixing hard particles to the first bonding surface with an adhesive layerAnd the step of attaching the hard particles to the second bonding surface may include attaching the hard particles to the first bonding surface and the second bonding surface with a first layer of a polymeric binder, wherein the first layer has a thickness of an average particle size (d) of the hard particles₅₀) At least 5%, and

embedding hard particles on the first and second joint surfaces with a second polymeric binder layer, wherein the second layer has a thickness of the average size (d) of the hard particles₅₀) At least 5% of the total weight of the composition.

In some embodiments of the methods disclosed herein, the step of affixing the hard particles to the first and second joint surfaces with a binder layer comprises affixing the hard particles to the first and second joint surfaces with a first layer of a polymeric binder layer, and the thickness of the first layer is the average particle size of the hard particles (d)₅₀) And the step of securing the hard particles to the first and second joint surfaces with a binder layer comprises embedding the hard particles on the first and second joint surfaces with a second layer of a polymeric binder layer, and the thickness of the second layer is the average particle size (d) of the hard particles₅₀) At least 10% of the total weight of the composition.

In some embodiments of the methods disclosed herein, the step of affixing the hard particles to the first and second joint surfaces with a binder layer comprises affixing the hard particles to the first and second joint surfaces with a first layer of a polymeric binder layer, and the thickness of the first layer is the average particle size of the hard particles (d)₅₀) And the step of securing the hard particles to the first and second joint surfaces with a binder layer comprises embedding the hard particles on the first and second joint surfaces with a second layer of a polymeric binder layer, and the thickness of the second layer is the average particle size (d) of the hard particles₅₀) At least 10% of the total weight of the composition.

In some embodiments of the methods disclosed herein, the step of securing the hard particles to the first and second bonding surfaces with a binder layer comprises securing the hard particles to the first and second bonding surfaces with a first layer of a polymeric binder layerOn both joining surfaces and the thickness of the first layer is the average particle size (d) of the hard particles₅₀) And the step of securing the hard particles to the first and second joint surfaces with a binder layer comprises embedding the hard particles on the first and second joint surfaces with a second layer of a polymeric binder layer, and the thickness of the second layer is the average particle size (d) of the hard particles₅₀) At least 20% of the total weight of the composition.

The hard particles may be fixed on the first joining surface and the second joining surface with an adhesive layer by cathodic dip coating. The adhesive layer comprises a polymeric material.

By cathodic dip coating, the part to be coated (i.e., the metal substrate) is immersed as a cathode into a coating bath having an aqueous dispersion of the coating material. In the methods disclosed herein, the coating material comprises hard particles and a polymeric material. The coating is deposited on the metal substrate by direct current from a dispersion comprising hard particles and a polymeric material. For cathodic dip coating, epoxy or acrylic materials can be used as the polymeric material. The coating bath is an aqueous bath and typically contains more than 50% water. The coating bath typically also contains an epoxy or acrylic material, pigments and organic solvents. Suitable organic solvents are, for example, low molecular weight alcohols, aliphatic and aromatic glycol ethers and ketones. Pigments used in the coating bath may be, for example, titanium dioxide, carbon black, iron oxide, kaolin, talc, lead and aluminum.

The hard particles are added to and suspended in the coating bath. Suitable methods for suspension are stirring, air injection or pumping. Dispersants may also be used. The hard particles are fixed on the first and second faying surfaces of the metal substrate due to deposition of the hard particles by sedimentation and growth of the polymer layer as a result of the direct current applied during cathodic dip coating.

The thickness of the coating material layer applied by cathodic dip coating is typically 2 μm to 60 μm, and may be, for example, 2 μm to 15 μm, 15 μm to 25 μm, 25 μm to 35 μm, and greater than 35 μm. After the application of the coating material layer, the obtained connection element may be cleaned, for example using deionized water. After the coating material layer is applied, the coating material layer is hardened, for example at a temperature of 150 ℃ to 220 ℃.

In some embodiments of the methods disclosed herein, the hard particles are affixed to the first and second faying surfaces with a polymeric binder layer by cathodic dip coating, and the hard particles are affixed to the first and second faying surfaces with a polymeric binder layer by a two-step process. In a first step, hard particles are fixed on the first and second bonding surfaces with a first layer of a polymeric binder layer. The thickness of the first layer is the average particle size (d) of the hard particles₅₀) At least 5%, or at least 10%, or at least 20%. The first step is performed by cathodic dip coating from a bath comprising a polymeric material and hard particles. In a second step, hard particles are embedded on the first and second bonding surfaces with a second layer of polymeric binder. The thickness of the second layer is the average particle size (d) of the hard particles₅₀) At least 5%, or at least 10%, or at least 20%. The second step is performed by cathodic dip coating of the polymeric material from an aqueous bath comprising the polymeric material. The material of the polymer binder layer of the first step may be the same as that of the polymer binder layer of the second step. The material of the polymeric binder layer of the first step may also be a different material than the material of the polymeric binder layer of the second step.

After the hard particles have been fixed on the first joining surface and the second joining surface with the binder layer by cathodic dip coating, another layer of polymeric material may be applied. The further layer may be, for example, an adhesive layer, such as a pressure sensitive adhesive layer. The pressure sensitive adhesive may be used for pre-assembling the connecting element. The pressure sensitive adhesive may be in the form of a tape, or adhesive microspheres sprayed onto the attachment elements. The other layer may also be a layer of grease applied by impregnation.

The hard particles may also be fixed on the first joining surface and the second joining surface with an adhesive layer by anodic dip coating. For anodic dip coating, an acrylic material, a phenolic resin modified acrylic material, an epoxy/polyester material, or polybutadiene oil may be used as the polymer material of the binder layer.

Fig. 1 shows a cross-sectional view of a connecting element as disclosed herein. The metal substrate 1 has a first bonding surface 2 on one side of the substrate 1 and a second bonding surface 3 on the opposite side of the substrate 1. Each joint surface 2,3 comprises hard particles 4 fixed to the metal substrate 1 by a binder layer 5. The adhesive layer 5 comprises a polymer material. In the example shown in fig. 1, the adhesive layer 5 consists of a polymer material.

A connecting element as disclosed herein is used in a method of frictionally coupling a first component and a second component, the method comprising:

there is provided a connecting element as disclosed herein,

providing a first component having a component engagement surface and a second component having a component engagement surface,

pressing the hard particles of the first engagement surface of the connecting element into the component engagement surface of the first component,

pressing the hard particles of the second joint surface of the connecting element into the component joint surface of the second part,

thereby frictionally coupling the first and second components with the connecting element.

The first engagement surface of the connecting element is brought into close contact with the component engagement surface of the first component and the second engagement surface of the connecting element is brought into close contact with the component engagement surface of the second component, and the first component and the second component are mechanically connected to each other, for example, with screws. The hard particles of the first bonding surface are pressed into the component bonding surface of the first component and the hard particles of the second bonding surface of the connecting element are pressed into the component bonding surface of the second component, thereby frictionally coupling the first and second components with the connecting element.

The present disclosure also relates to a friction joint comprising a first component having a component engagement surface, a second component having a component engagement surface, and a connecting element as disclosed herein, wherein the first component and the second component are in frictional engagement with the connecting element.

The connecting elements disclosed herein may be used to connect first and second components to be joined in machines, equipment and motor vehicle structures and energy generation. The connection elements disclosed herein may be used for friction increasing connections of first and second components to be joined in machines, equipment and motor vehicle structures and energy generation. The connection elements disclosed herein may be used for friction-increasing, play-free and/or reversible connections of first and second components to be joined in machines, equipment and motor vehicle structures and energy generation.

In principle, the connecting element disclosed herein can be used for any type of frictional connection throughout the field of mechanical engineering, in particular in the case of insufficient forces that can be transmitted through the component surfaces imposed by the design.

For example, the connecting elements disclosed herein may be used in a frictional connection (such as a bolted or clamped connection) between parts or components of a vehicle, such as a subframe and a chassis, or a crankshaft and a sprocket, or a camshaft application, or an axle or damper application, or between parts or components of a wind turbine, or in a damper application, or (such as a segmented tower or wind hub and wind wheel shaft).

The present disclosure will be described in more detail by the following examples.

Examples

Examples 1 to 4(EX1, EX2, EX3, EX4)

Preparation of connecting elements (as used in examples 1 to 4)

For examples 1 to 4, the dimensions will be 0.8X 76X 152mm³The steel sheet (steel grade DC01) was used as test substrate and coated in a 3 liter beaker with a Cathodic Dip Coating (CDC) apparatus consisting of a rectifier (model SVI 4020, Gorkotte GmbH of Frankfurt, Germany) and a protective housing. 3 liters of epoxy resin CDC varnish (KTL-EP-Grundierung 5606, Brillux GmbH from Wenna, Germany) in a mass ratio of 4:5 was charged into a beaker&Kg industrilack) and deionized water. 20g of average particle size (d)₅₀) Diamond at 35 μm was dispersed in the varnish-water mixture.The dispersion obtained is stirred while being heated on a hotplate (Hei-Tec, Heidolph Instruments GmbH from Schwabach, N ü rnberg, Germany)&Kg) was heated to 30 ℃. The speed of the stirrer depends on the diamond concentration, the minimum speed being defined as the speed at which there is no diamond at the bottom of the beaker, which in this setup is equal to about 200rpm with a magnetic stirrer.

The test substrate is mounted at the cathode of the CDC apparatus by means of a clamping tool, which enables electrical contact of the coating process. The test substrate was positioned at an angle of about 20 ° to the vertical axis so that the diamonds could settle on the inclined steel plate. Sedimentation occurs when the stirring is stopped. After stopping stirring and waiting for 5 seconds, coating was performed at a voltage of 200V for 2.5 seconds. Thus, a very thin layer of epoxy-based polymer of 1 μm to 2 μm is deposited on the steel plate and the diamond is fixed on the upper bonding surface by the thin layer of epoxy-based polymer. Due to the inclined steel plate, the diamond is fixed on only one of the bonding surfaces. Diamond must also be deposited on the opposite joint surface and therefore the coating is repeated with the steel plate turned to the opposite side. Thus, both bonding surfaces are coated with diamond fixed by a thin layer of 3 to 4 μm epoxy-based polymer.

In order to fasten the diamond even better in the epoxy-based polymer layer, a further coating step is carried out, in which only the polymer, and not the diamond, is deposited. Thus, the substrate was placed in a vertical position and coating was performed at a voltage of 200V without stirring for 15 to 30 seconds.

The coating time in the vertical position was 15 seconds for example 1, 20 seconds for example 2, 25 seconds for example 3, and 30 seconds for example 4. The epoxy-based polymer layer with the diamonds fixed by the polymer is coated with the epoxy-based polymer layer on both sides, thereby embedding the diamonds together with the other polymer layer.

After coating, the epoxy-based polymer coated part with embedded diamonds was removed from the beaker and carefully cleaned with a water jet of deionized water to remove the un-deposited polymer components and the diamond particles that were not embedded in the polymer matrix. After cleaning, the coated part was tempered in an oven at 180 ℃ for 25 minutes to harden the epoxy-based polymer coating.

The test substrate was almost uniformly covered with diamond on both sides. The nearly uniform coverage is a result of the precipitation of diamond particles after the stirring is stopped. The diamond particles were kept suspended in the varnish-water mixture by stirring. The waiting time after stirring and before coating depends on the total diamond concentration in the suspension. The higher the concentration of diamond particles, the longer the waiting time to achieve uniform diamond coverage.

The percentage of diamond covered area of the two side bonding surfaces (also referred to herein as diamond coverage) was measured using a Leica microscope with the software Leica Qwin. The grayscale microscope image was analyzed by threshold transformation. Ten measurements were performed on each of the two joining surfaces, the average values being shown in table 1.

The topography of the polymer and diamond coated bonding surfaces was studied using an optical microscope (Keyence VHX 5000). Microscopic images show that the diamond is embedded in the polymer coating to a size of about half its size. About half of the height of the diamond (i.e., about 17 μm) protrudes from the surface.

With optical film thickness gauge (Pocket)X, PHYNIX GmbH from Germany&Kg) the thickness of the polymer coating was measured. A total of twelve measurements (six times per side of the coated substrate) were performed to determine the thickness. The average of twelve measurements is shown in table 1.

Comparative example 1(CEX1)

Preparation of connecting elements (e.g. for comparison 1)

For comparative example 1, the dimensions were 0.8X 76X 152mm³Steel sheet (steel grade DC01) was used as a substrate and a cathode consisting of a rectifier (model SVI 4020, Gorkotte GmbH of Frankfurt, Germany) and a protective shell was used in a 3 liter beakerDip Coating (CDC) apparatus. 3 liters of epoxy resin CDC varnish (KTL-EP-Grundierung 5606, Brillux GmbH from Wenna, Germany) in a mass ratio of 4:5 was charged into a beaker&Kg industrilack) and deionized water.

The varnish-water mixture was heated to 30 ℃ on a hotplate (Hei-Tec, Heidolph Instruments GmbH & Co. KG., Schwabach, N ü rnberg, Germany) and stirred at 600 rpm. The coating process was carried out while continuing the stirring. The substrate is mounted at the cathode of the CDC-apparatus by means of a clamping tool, which enables electrical contact of the coating process. The substrate was placed in a vertical position and coated for 2 minutes at a voltage of 200V. The substrate was coated on both sides with a layer of an epoxy-based polymer having a layer thickness of about 20 μm. The thickness of the polymer coating was measured using an optical film thickness gauge as described above.

After coating, the polymer coated parts were removed from the beaker and carefully cleaned with a water jet of deionized water to remove the undeposited polymer component. After cleaning, the coated parts were tempered in an oven at 180 ℃ for 25 minutes to harden the polymer coating.

Comparative example 2(CEX2)

Preparation of connecting elements (as for comparative example 2)

For the preparation of the connecting element, a nickel layer and an average particle diameter (d) are applied by electroless plating₅₀) Diamond of 35 μm was coated on both bonding surfaces with a ring-shaped steel foil (steel grade DC01) of thickness 0.1mm, outer diameter 30mm and inner diameter 15 mm. As used herein, the annular steel foil is also referred to as a "shim".

Average particle size (d) by electroless nickel coating₅₀) The shim was coated with 35 μm diamond which was held in place by a layer of nickel of 17 μm thickness. For electroless nickel plating, the gasket is placed on a suitable frame and pretreated by degreasing, pickling and activation according to the general rules of electroless nickel plating. Then, the support bearing the gasket was immersed in an electroless nickel plating solution in which diamond powder having an average particle diameter of 35 μm was dispersed. SelectingThe amount of dispersed diamond powder is chosen such that, under the main parameters in the coating bath (bath movement, deposition rate), the desired diamond proportion is achieved in the nickel deposition layer and the nickel layer reaches the desired thickness. Under conventional process conditions, the immersion time was about 60 minutes.

The carrier, including the now electroless nickel plated shim, was then removed from the electroless nickel bath and cleaned in an ultrasonic bath to remove the diamond particles that only loosely adhered to the nickel layer. The cleaned mat is removed from the carrier and heat treated at a temperature of at least 150 ℃ for 2 hours. This treatment increases the adhesion of the electroless nickel layer to the steel foil and the bonding of the diamond in the layer itself.

The percentage of diamond covered area of the bonding surface was 15% on both sides.

Friction test

For the friction test, test substrates having a diamond-polymer coating (examples 1 to 4) and a polymer coating (comparative example 1), respectively, were cut to 35X 35mm²Square of (2). Two of these squares are necessary for each test.

The coefficient of static friction was determined by experimental means, wherein the frictional contact was produced by clamping a central steel block (steel S355) of dimensions 14 x 25mm between two steel blocks (S355; block 1, block 2) of larger dimensions (30 x 25mm), which were pressed onto the central block by a defined force representing the normal force. The normal force is generated using a clamping mechanism that uses at least two large screws. The contact pressure tested was 50 MPa.

For examples 1 to 4 and comparative example 1, one of the square samples was positioned between block 1 and the central block, and the other connecting element was positioned between block 2 and the central block. Two connecting elements were prepared as described above, having the thickness of the metal adhesive layer as shown in table 1.

The outer blocks (block 1, block 2) are positioned on a rigid and flat substrate. The center block is centrally located with respect to the outer blocks. This results in a defined distance of the central block from the substrate.

The shear test was performed by applying a compressive load to the center block from the top via the piston. The compressive load represents the frictional force. The test was carried out using a universal tester (Zwick GmbH, model 1474). The friction increases until the central block starts to move in the direction towards the substrate relative to the outer blocks (which cannot move because they are positioned on the substrate). The maximum movement of the center block is set to 500 μm. During the shear test, the normal force, the friction force and the distance of the center block from the substrate were measured continuously.

The friction coefficient, defined as the ratio of friction/normal force, was calculated using the measurements of friction and normal force. The movement of the center block relative to the outer blocks is calculated using the measured distance of the center block from the substrate. In this way, the coefficient of friction may be obtained from the measured relative movement representing the friction behavior or friction curve. The friction curve is used to determine a characteristic value, for example a defined relative movement or a characteristic value of the maximum friction coefficient corresponding to the maximum value of the friction curve. The coefficient of static friction μ is defined as the coefficient of friction at a relative motion of 20 μm or, if the relative motion at the maximum of the friction curve is below 20 μm, as the maximum coefficient of friction.

The results of the friction test of examples 1 to 4 and comparative example 1 are shown in table 1.

TABLE 1：

Corrosion testing

According to EN ISO 9227:2017, using commercially available test equipment (corrosion test box model HK400, Lippstadt, Germany)Automobiltechnik) as neutral salt spray test. For this test, test substrates with diamond-polymer coatings (examples 1 to 4) were cut to 35X 35mm²Is square, andplaced in a plastic sample holder. For comparison, a shim with a diamond-nickel coating (comparative example 2) was also placed in the plastic sample holder.

The glass sample holder with the coated test substrate was placed in a test chamber for 48 hours. The test conditions were:

temperature range: 35 ℃/2 DEG C

Concentration of sodium chloride solution: 50 g/l. + -. 5g/l

pH value: 6.5-7.2

Condensation Rate (horizontal area, 80 cm)²)：1.5ml/h±0.5ml/h

After testing, the pads were rinsed with deionized water and dried in a 110 ℃. + -. 5 ℃ oven for two hours. After drying, the test pads were visually inspected.

The results of the corrosion test are shown in table 2.

TABLE 2：

As used herein, mild corrosion is defined as a single rusty spot that is less than 5% of the total surface area. As used herein, severe corrosion is defined as a mass of rusted areas up to 50% of the total surface area.

These embodiments demonstrate that connecting elements as disclosed herein can have a static coefficient of friction of 0.4 or higher, and thus are suitable for many applications of frictional connections. The connecting elements as disclosed herein may have improved corrosion resistance in humid environments (e.g., outdoors). Improved corrosion resistance is important for all applications where the friction connection is exposed to moisture, water or any other humid environment.