阅读说明：本技术 封入含石墨烯材料中的粒状载体材料和滑动元件的制造方法、以及滑动元件、滑环密封件和轴承装置 (Method for producing particulate carrier material and sliding element sealed in graphene-containing material, sliding element, slip ring seal, and bearing device ) 是由 R·穆尔霍普特 约尔格·泰勒科 文利·张 于 2018-07-05 设计创作，主要内容包括：本发明涉及具有第一滑动面的滑动元件,其中所述第一滑动面(29)包括粒状载体材料(6)和含石墨烯材料(7),其中所述粒状载体材料(6)至少部分地覆盖有含石墨烯材料(7),以及材料配合连接(14)在粒状载体材料(6)和含石墨烯材料(7)之间建立。(The invention relates to a sliding element having a first sliding surface, wherein the first sliding surface (29) comprises a particulate carrier material (6) and a graphene-containing material (7), wherein the particulate carrier material (6) is at least partially covered with the graphene-containing material (7), and a material-fit connection (14) is established between the particulate carrier material (6) and the graphene-containing material (7).)

1. A sliding element comprises a first sliding surface (29),

-the first sliding surface (29) comprises a particulate carrier material (6) and a graphene-containing material (7),

-a particulate support material (6) is at least partially covered with the graphene-containing material (7), and

-there is a material fit connection (14) between the particulate support material (6) and the graphene-containing material (7).

2. The sliding element according to claim 1, wherein the particulate carrier material (6) is completely covered by the graphene-containing material (7).

3. The sliding element according to claim 1 or 2, further comprising a first matrix having only the particulate carrier material (6).

4. The sliding element according to any one of the preceding claims, wherein the first sliding surface consists of a mixture of a particulate carrier material (6) and a particulate carrier material (5) covered with a graphene-containing material.

5. The sliding element according to claim 4, wherein the mass ratio of the particulate carrier material (6) and the particulate carrier material (5) covered with the graphene-containing material is 80:20 to 99.5:0.5, in particular 90:10 to 99.5: 0.5.

6. The sliding element according to any one of the preceding claims, wherein the granular carrier material (6) is composed of a ceramic material, in particular selected from the group consisting of: SiC, WC, B₄C、BN、Si₃N₄、Al₂O₃、MgO、ZrO₂And mixtures thereof, in particular SiC.

7. The sliding element according to any of the preceding claims, the graphene-containing coating comprising one to 100 layers (7a, 7b, 7c, 7d) of the graphene-containing material (7), in particular one to 20 layers (7a, 7b, 7c, 7d) of the graphene-containing material (7) and in particular one to 12 layers (7a, 7b, 7c, 7d) of the graphene-containing material (7).

8. The sliding element according to any one of the preceding claims, the first sliding surface (29) having a macroporosity of between 6 and 8% by volume relative to the total volume of the first sliding surface (29).

9. A mechanical seal, comprising:

-a rotating first slip ring (2) having a first sliding surface (29) and a stationary second slip ring (3) having a second sliding surface (30) defining a sealing gap (4) therebetween,

-the first slip ring (2) and/or the second slip ring (3) is a sliding element according to any of the preceding claims.

10. Bearing arrangement, in particular a sliding bearing or rolling bearing, in particular a radial sliding bearing (41) or an axial sliding bearing (42), comprising at least one sliding element according to any one of claims 1 to 8.

11. A method of manufacturing a particulate support material (5) covered with a graphene-containing material, comprising the steps of:

-dispersing (100) a particulate carrier material (6) in a dispersing agent (17),

-adding (200) a carbon source (15), in particular a carbon-containing compound (15),

-removing (300) the dispersant (17) to obtain a solid substance (16), and

-carbonizing (400) the carbon source (15) to at least partially, in particular completely, cover the particulate support material (6) with the graphene-containing material (7).

12. The method according to claim 11, wherein the carbon source (15) is selected from the group consisting of: furfuryl alcohol, glucose, and mixtures thereof.

13. The method according to claim 11 or 12, wherein the solid matter (16) obtained after removal of the dispersing agent (17) is comminuted before carbonization.

14. The process according to any one of claims 11 to 13, wherein the carbonization is carried out in a two-step temperature process under an inert atmosphere, wherein in the first temperature step the solid matter (16) is heated to 80 to 180 ℃ at a heating rate of 5 ℃/min and is kept at this temperature range for 15 to 25 hours, and in the second temperature step the solid matter (16) is heated to 600 to 1500 ℃ at a heating rate of 5 ℃/min and is kept at this temperature range for 4 to 8 hours.

Technical Field

The present invention relates to a method for producing a particulate support material covered with a graphene-containing material and a method for producing a sliding element. Further, the present invention relates to a sliding element having excellent stability and low wear, and a mechanical seal and a bearing device including the sliding element.

Background

Mechanical seals are known from the prior art, for example from DE 102014205291 a1, which contain SiC as a base material supplemented with graphene as a filler. Mechanical seals are characterized by good fracture toughness and flexural strength. The disadvantages are a rather low hardness and a low modulus of elasticity. This reduces wear resistance, making the mechanical seal less suitable for systems that are subjected to mechanical and/or thermal shock.

Disclosure of Invention

It is therefore an object of the present invention to provide sliding elements, mechanical seals and bearing arrangements which are characterized by improved wear resistance and hardness and thus increased stability even under high mechanical and/or thermal shocks. Furthermore, it is an object of the present invention to provide a method for manufacturing a particulate support material covered with a graphene-containing material, and a method for manufacturing a sliding element, which methods are characterized by simple feasibility, wherein in the former method, the particulate support material covered with the graphene-containing material will be obtained in high yield.

This object is achieved by a sliding element according to claim 1. The sliding element of the present invention includes a first sliding surface which is in sliding contact with another component or can be in sliding contact with another component.

Here, the first sliding surface comprises a particulate carrier material and a graphene-containing material.

By particulate support material, material is meant a substrate that serves as an application of the graphene-containing material, i.e. serves as a base material. The particulate support material is in the form of particles which are at least partially, in particular completely, covered with the graphene-containing material.

Within the scope of the present invention, for graphene-containing materials, the material is understood to consist at least partially of graphene. Preferably, the entire graphene material consists of graphene, with the exception of technically unavoidable residues.

The presence of a material mating connection (stoffschl ü missing graphene material) between the particulate support material and the graphene-containing material means that a mating connection is established between the particulate support material and the graphene-containing material, wherein the graphene-containing material is directly attached to the surface of the particulate support material.

The sliding element is thus characterized by a high hardness and a high modulus of elasticity even at high mechanical shocks and high temperatures, which ensures high wear resistance of the sliding element and at the same time good sliding properties.

Advantageous embodiments and improvements (fur definitions) of the invention are the subject matter of the dependent claims.

According to an advantageous development, the particulate support material is completely covered by the graphene-containing material. This means that the entire particle surface of the particulate support material is covered by the graphene-containing material. This improves the wear resistance of the sliding element while maximizing the elastic modulus.

Still advantageously, the sliding element comprises a first base body. The basic body is to be regarded as a lower body on or at which a suitable sliding surface is to be applied or formed, respectively. In order to improve the bond between the base body and the sliding surface, the first base body only has a granular carrier material. In other words, this means that the first substrate is made of the same particulate support material as the particulate support material covered with the graphene-containing material, but that the first substrate is not covered with the graphene-containing material, unlike the particulate support material contained in the first sliding surface.

In order to improve the slidability and the good stability, the entire first sliding surface is preferably formed from a carrier material coated with a graphene-containing material, or further advantageously the entire sliding element is formed solely from a carrier material coated with a graphene-containing material. This may also reduce or even prevent the formation of cracks in the graphene-containing material.

In order to reduce costs while maintaining a good hardness of the sliding surface and/or of the sliding element, it is advantageously provided that the first sliding surface is composed of a mixture of a particulate support material and a particulate support material covered with a graphene-containing material.

Still advantageously, the mass ratio of the particulate support material and the particulate support material covered with the graphene-containing material is from 80:20 to 99.5:0.5, in particular from 90:10 to 99.5: 0.5. Despite the low graphene feed, very good wear resistance of the first sliding surface can be achieved. Therefore, the sliding element can be manufactured at low cost.

In order to further improve the wear resistance of the first sliding surface by increasing its hardness, a ceramic material will preferably be used as the particulate support material. Ceramic materials, i.e. sintered ceramics, have proven to be particularly resistant to wear even under severe conditions such as high mechanical and/or thermal shocks. Advantageously, the ceramic material will be selected from the group consisting of: SiC, WC, B₄C、BN、Si₃N₄、Al₂O₃、MgO、ZrO₂And any mixtures thereof, wherein SiC is particularly preferred for cost reasons.

In view of further improving the wear resistance of the first sliding surface of the sliding element, it is also advantageously provided that the graphene-containing coating comprises from one to 100, in particular from one to 20, in particular from one to 12, layers of graphene-containing material. The layer structure also allows optimizing the friction of the sliding element.

The significant reduction in the potential wear value of the first sliding surface can be achieved by an advantageous development, wherein the first sliding surface contains 6 to 8 vol.% of macroporosity relative to the total volume of the first sliding surface. In this context, macropores in the sense of the present invention are pores having a pore diameter of 10 to 50 μm. The pore size was determined by the LSM method (laser scanning microscope). Preferably, the first sliding surface has no micropores with a pore diameter of 1 to 10 μm. The absence of pores means that there are no microporosities between the particulate support material coated with the graphene-containing material and any uncoated particulate support material. Therefore, the density of the first sliding surface is optimized, so that the wear resistance can also be increased while maintaining good sliding properties.

Furthermore, according to the invention, a mechanical seal is also described. The mechanical seal according to the invention comprises a rotating first seal ring having a first sliding surface and a stationary second seal ring having a second sliding surface, which define a seal gap therebetween. As mentioned above, in the mechanical seal according to the invention, the first sealing ring or the second sealing ring, or in particular both sealing rings, are designed in the shape of the sliding element according to the invention. By forming one or even both sealing rings of the mechanical seal in the shape of the sliding element according to the invention, the mechanical seal according to the invention can achieve high hardness and a high modulus of elasticity even at high mechanical shocks and high temperatures, thereby obtaining high wear resistance of the first and/or second sealing ring while maintaining good sliding properties.

Furthermore, a bearing arrangement comprising at least one sliding element as described above is described according to the invention. The bearing means may for example be in the form of a sliding bearing or a rolling bearing. The design of the sliding bearing, in particular a radial sliding bearing or an axial sliding bearing, is particularly preferred. One or both sliding elements or one or both sliding surfaces of the plain bearing are preferably designed according to the sliding element according to the invention. Such a bearing device is preferably used for pumps or magnetic couplings.

The bearing arrangement preferably comprises at least one outer raceway (radial) and one inner raceway, the rolling bearing further comprising rolling elements. According to the invention, as mentioned above, the outer or inner raceway or both raceways are designed in the form of a sliding element according to the invention. If the bearing device is a rolling bearing, one or more rolling elements in the form of sliding elements according to the invention can alternatively or additionally be designed. This enables very good wear resistance of the bearing arrangement to be achieved even at high temperatures and high mechanical shocks, while providing very good sliding properties.

Also according to the present invention, a method of manufacturing a particulate support material covered with a graphene-containing material will be described. Due to their very good mechanical properties, the carrier materials produced can be used in particular for improving the wear resistance of sliding elements, for example sealing rings or sliding surfaces of bearing arrangements.

The method first comprises the step of dispersing a particulate carrier material in a dispersant. The particulate carrier material and the dispersant are not particularly limited. In particular, the particulate carrier material may be formed as described above in relation to the sliding element according to the invention and, for this purpose, may advantageously comprise at least one ceramic material, and in particular SiC. As the dispersing agent, a medium is selected which can easily disperse the particulate carrier material. For cost and environmental reasons, aqueous and/or alcoholic dispersants, especially ethanol-containing dispersants, are preferred. The dispersion can be carried out, for example, using ultrasound and/or a stirrer and/or a homogenizer. Good dispersion of the particles of the particulate carrier material in the dispersant is of crucial importance.

In a further step, the addition of a carbon source, in particular a carbon-containing compound, is carried out. The compounds are suitable, when processed appropriately, for the production of graphene-containing materials. In other words, the carbon source is a graphene precursor.

Subsequently, the dispersant will be removed while a solid substance is obtained. Common processing steps may be employed herein, such as removal of the dispersant by temperature application, evaporation of the dispersant in a rotary evaporator, or freeze drying. The solid matter will remain from the carbon source for the graphene-containing material to be formed and the particulate support material, with the carbon source disposed on top of the particulate support material.

Followed by the step of carbonizing the compound. The carbonization is carried out under temperature treatment such that the graphene-containing material at least partially, in particular completely, covers the particulate support material. The heat treatment required for this can be carried out in a tube furnace, the temperature of which can be easily controlled.

The direct carbonization of the graphene precursors disposed on the surface of the particulate support material produces a material-fitted connection between the support material and the manufactured graphene. The graphene-containing coating is thus permanently bonded to the particulate support material in a strong and stable manner, resulting in high abrasion resistance. The process is easy to carry out, enabling the production of a particulate support material coated with a graphene-containing material in high yield.

For environmental reasons and also because the carbon source is derived from renewable raw materials, the carbon source is advantageously selected from the group consisting of: furfuryl alcohol, glucose, and any mixture thereof. In addition, these compounds readily form graphene under heat treatment with high yield.

In order to increase the yield of the particulate support material covered with the graphene-containing material, the solid matter obtained after removal of the dispersant is preferably pulverized before carbonization. After comminution, the solid substance has a particle size of less than 1mm, in particular less than 0.1 mm. Therefore, the temperature treatment can also be uniformly performed while forming the graphene-containing coating layer.

A temperature process comprising at least two steps has proven to be particularly advantageous for the formation of graphene-containing coatings of particulate support materials. The carbonization is in particular carried out in a two-step temperature process under an inert atmosphere, wherein in a first temperature step the solid matter is heated to 80 to 180 ℃ with a heating rate of 5 ℃/min and is maintained in this temperature range for 15 to 25 hours, and in a second temperature step the solid matter is heated to 600 to 1500 ℃ with a heating rate of 5 ℃/min and is maintained in this temperature range for 4 to 8 hours. This allows an almost complete conversion of the graphene precursor into graphene, so that the coating surrounding the particulate support material is mostly composed of graphene, except for technically unavoidable residues.

In the following, advantageous improvements of the manufacture of a particulate support material covered with a graphene-containing material will be disclosed.

For the production of graphene-coated SiC using Furfuryl Alcohol (FA) (SiC: furfuryl alcohol 90:10, wt.%), SiC (152.55g) was dispersed in water (200 mL). Furfuryl alcohol (15mL) was then added. Stirring for 10min, and adding p-TsO as initiatorH (0.33g) was dissolved in water (10mL) and added to the SiC/FA mixture. After stirring for a further 20min, the reaction mixture was heated to 80 ℃. The mixture was then added to the SiC/FA mixture. After 1h, the mixture was kept at 100 ℃ for another 6h until the water evaporated. After comminution, the dry powder is placed in a tube furnace under an inert atmosphere (N)₂) Medium carbonization (pyrolysis). This was done by heating to 150 ℃ in steps of 5 ℃/min (steps), holding for 21h, then increasing to 800 ℃ in steps of 5 ℃/min and pyrolysing for 6 h. Here, functionalized graphene is produced in a template-mediated reaction with furfuryl alcohol as a carbon source, with SiC serving as the template. A homogeneous mixture of graphene and SiC was also obtained. The graphene coating greatly changes the specific surface area (from 10 to 39 m)²/g), and the color of SiC, the specific surface area being determined by the BET method by N, for example, using Sorptomatic 1990(Protec Hofheim)₂Adsorption to determine the mass-related specific surface area of the sample by detecting the amount of nitrogen adsorbed onto the surface of the sample.

The morphology of SiC particles and graphene-coated SiC can be analyzed by TEM. A thin graphene layer will result. The SiC particles are covered with about eight graphene layers. The graphene content of the resulting product was 4.4 wt%.

Alternatively, for the manufacture of graphene-coated SiC using furfuryl alcohol (SiC: furfuryl alcohol 80:20 wt%), SiC (90.40g) was dispersed in ethanol (200 mL). Furfuryl alcohol (20mL) was then added. After stirring for 10min, p-TsOH (0.44g) as initiator was dissolved in ethanol (10ml) and added to the SiC/FA mixture. After stirring for a further 20min, the reaction mixture was heated to 70 ℃. The mixture was then added to the SiC/FA mixture. After 3h, the mixture was kept at 100 ℃ for a further 2 h. Removal of the remaining ethanol was accomplished using a rotary evaporator. After comminution, the dry powder is placed in a tube furnace under an inert atmosphere (N)₂) And (5) medium carbonization. This was done by heating to 150 ℃ in steps of 5 ℃/min, holding for 21h, then increasing to 800 ℃ in steps of 5 ℃/min and pyrolysing for 6 h. The powder is then placed in a tube furnace under an inert atmosphere (N)₂) And (5) medium carbonization. The resulting product had a graphene content of 7.6 wt% and 53m²Specific surface area in g, as determined by Sorptomatic 1990(Protec Hofheim)) By N using BET method₂Adsorption to determine the mass-related specific surface area of the sample by detecting the amount of nitrogen adsorbed onto the surface of the sample.

Alternatively, for the production of graphene-coated SiC using furfuryl alcohol (SiC: furfuryl alcohol 70:30 wt%), SiC (105.47g) was dispersed in ethanol (200mL), followed by the addition of furfuryl alcohol (40 mL). After stirring for 10min, p-TsOH (0.88g) as initiator was dissolved in ethanol (10mL) and added to the SiC/FA mixture. After stirring for a further 20min, the reaction mixture was heated to 70 ℃. The mixture was then added to the SiC/FA mixture. After 4h, the mixture was kept at 100 ℃ for a further 2 h. The remaining ethanol was removed using a rotary evaporator. After comminution, the dry powder is placed in a tube furnace under an inert atmosphere (N)₂) And (5) medium carbonization. This was done by heating to 150 ℃ in steps of 5 ℃/min, holding for 21h, then increasing to 800 ℃ in steps of 5 ℃/min and pyrolysing for 6 h. The powder is then placed in a tube furnace under an inert atmosphere (N)₂) And (5) medium carbonization. The resulting product had a graphene content of 14.3 wt.% and 100m²Specific surface area in g, e.g.by N using the BET method using Sorptomatic 1990(Protec Hofheim)₂Adsorption to determine the mass-related specific surface area of the sample by detecting the amount of nitrogen adsorbed onto the surface of the sample.

For the manufacture of graphene-coated SiC using glucose (SiC: glucose 90:10, wt%), SiC (20g) was dispersed in water (90mL) by means of an ultrasonic bath (2 × 15 min). A solution of glucose (2.00g) in water (10mL) was then added. After pre-dispersion by means of an ultrasonic bath (2 x 15min), the reaction mixture was completely dispersed under ice-cooling by means of an ultrasonic spray gun (2-8min, 40% amplitude). The water was then removed by freeze drying. After comminution, the dry powder is placed in a tube furnace under an inert atmosphere (N)₂) And (5) medium carbonization. This was done by heating to 150 ℃ in steps of 5 ℃/min, holding for 21h, then increasing to 800 ℃ in steps of 5 ℃/min and pyrolysing for 6 h. The powder is then placed in a tube furnace under an inert atmosphere (N)₂) And (5) medium carbonization. Here, instead of using furfuryl alcohol, functionalized graphene is produced in a template-mediated reaction using glucose as a carbon source, with SiC serving as the template. And alsoA homogeneous mixture of graphene and SiC is obtained. The graphene coating greatly changes the specific surface area, as well as the color of SiC, by the BET method using, for example, Sorptomatic 1990(Protec Hofheim) using the BET method₂Adsorption to determine the mass-related specific surface area of the sample (from 10 to 20 m) by detecting the amount of nitrogen adsorbed onto the surface of the sample²/g)。

The morphology of the resulting product can be analyzed by TEM. All SiC particles have about 7 to 20 graphene layers. The graphene content of the product was 2.0 wt%.

Alternatively, for the manufacture of graphene-coated SiC using glucose (SiC: glucose 80:20 wt%), SiC (30g) was dispersed in water (70mL) by means of an ultrasonic bath (2 × 15 min). A solution of glucose (7.50g) in water (30mL) was then added. After pre-dispersion by means of an ultrasonic bath (2 x 15min), the reaction mixture was completely dispersed by means of an ultrasonic spray gun (2 x 8min, 40% amplitude) under ice-cooling. The water was then removed by freeze drying. After comminution, the dry powder is placed in a tube furnace under an inert atmosphere (N)₂) And (5) medium carbonization. This was done by heating to 150 ℃ in steps of 5 ℃/min, holding for 21h, then increasing to 800 ℃ in steps of 5 ℃/min and pyrolysing for 6 h.

The product had a graphene content of 5.2 wt.% and 39m²Specific surface area in g, e.g.by N using the BET method using Sorptomatic 1990(Protec Hofheim)₂Adsorption to determine the mass-related specific surface area of the sample by detecting the amount of nitrogen adsorbed onto the surface of the sample.

Alternatively, for the manufacture of graphene-coated SiC using glucose (SiC: glucose 70:30, wt%), SiC (30g) was dispersed in water (70mL) by means of an ultrasonic bath (2 × 15 min). Subsequently, a solution of glucose (12.86g) in water (30mL) was added. After pre-dispersion by means of an ultrasonic bath (2 x 15min), the reaction mixture was completely dispersed by means of an ultrasonic spray gun (2 x 8min, 40% amplitude) under ice-cooling. The water was then removed by freeze drying. After comminution, the dry powder is placed in a tube furnace under an inert atmosphere (N)₂) And (5) medium carbonization. This was done by heating to 150 ℃ in steps of 5 ℃/min for 21h, thenIncreasing to 800 ℃ in steps of 5 ℃/min and pyrolyzing for 6 h.

The product had a graphene content of 8.8 wt.% and 57m²Specific surface area in g, e.g.by N using the BET method using Sorptomatic 1990(Protec Hofheim)₂Adsorption to determine the mass-related specific surface area of the sample by detecting the amount of nitrogen adsorbed onto the surface of the sample.

Alternatively, for the manufacture of graphene-coated SiC using glucose (SiC: glucose 60:40, wt%), SiC (30g) was dispersed in water (70mL) by means of an ultrasonic bath (2 × 15 min). A solution of glucose (20.00g) in water (30mL) was then added. After pre-dispersion by means of an ultrasonic bath (2 x 15min), the reaction mixture was completely dispersed by means of an ultrasonic spray gun (2 x 8min, 40% amplitude) under ice-cooling. The water was then removed by freeze drying. After comminution, the dry powder is placed in a tube furnace under an inert atmosphere (N)₂) And (5) medium carbonization. This was done by heating to 150 ℃ in steps of 5 ℃/min, holding for 21h, then increasing to 800 ℃ in steps of 5 ℃/min and pyrolysing for 6 h.

The product had a graphene content of 13.4 wt.% and 76m²Specific surface area in g, e.g.by N using the BET method using Sorptomatic 1990(Protec Hofheim)₂Adsorption to determine the mass-related specific surface area of the sample by detecting the amount of nitrogen adsorbed onto the surface of the sample.

Furthermore, according to the invention, a method for manufacturing a sliding element is described. Thereby, the method is also suitable for manufacturing bearing devices and slip rings as used in the above-mentioned mechanical seals. With regard to advantages, advantageous effects and improvements, therefore, reference is additionally made to the sliding element according to the invention as described above.

In the method according to the invention, a sliding element is produced, which comprises a specifically designed sliding surface. To this end, a mixture comprising a particulate support material and a particulate support material at least partially, in particular completely, covered with a graphene-containing material is produced in one step. For example, by the above-described method for producing a particulate support material covered with a graphene-containing material, a particulate support material covered with a graphene-containing material can be obtained. The mixing can be carried out in a conventional manner, for example using a stirrer and/or a homogenizer and/or ultrasound.

The mixture itself can be formed as a sliding element, but can also be applied, for example, to a matrix, in particular consisting of a granular carrier material, which then forms only the sliding surface of the sliding element.

In a further step, a sintering procedure of the mixture is added, resulting in a material-fit connection, i.e. sinter bonding, between the particulate support material and the support material coated with the graphene-containing material. Specifically, a nonporous sliding surface is produced in the sintering process. The sliding elements produced by the method according to the invention are characterized by high stability and wear resistance even under high mechanical and/or thermal shock in a simple and thus also cost-effective manufacturing method.

In order to increase the hardness of the sliding surface, the particulate carrier material is advantageously selected from ceramic materials, in particular selected from the group consisting of: SiC, WC, B₄C、BN、Si₃N₄、Al₂O₃、MgO、ZrO₂And any mixtures thereof, in particular consisting of SiC.

In order to further reduce the costs while maintaining a high stability of the sliding element, the mixture is applied to a substrate, in particular a substrate consisting of a ceramic material, in particular selected from the group consisting of: SiC, WC, B₄C、BN、Si₃N₄、Al₂O₃、MgO、ZrO₂And any mixtures thereof, and in particular SiC.

Drawings

Hereinafter, preferred exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, identical or functionally identical components are identified with identical reference numerals, wherein:

FIG. 1 is a schematic cross-sectional view of a mechanical seal according to a first exemplary embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of the second slip ring shown in FIG. 1;

fig. 3 is a longitudinal schematic view of a bearing arrangement according to a second exemplary embodiment of the invention;

FIG. 4 is a cross-section of the bearing assembly shown in FIG. 3;

FIG. 5 is a schematic cross-sectional view of the particulate support material covered with graphene-containing material of the stationary slip ring shown in FIG. 2;

fig. 6 is a schematic illustration of a method of manufacturing a particulate support material covered with a graphene-containing material according to an embodiment of the invention;

fig. 7 is a schematic illustration of a method of manufacturing a sliding element according to an embodiment of the invention.

Detailed Description

The present invention is described in detail by way of exemplary embodiments. The drawings show only the essential features of the invention, and all other features have been omitted for the sake of clarity. Further, like reference numerals denote like elements.

Fig. 1 schematically shows a mechanical seal arrangement 1 comprising a rotating slip ring 2 having a first sliding surface 29 and a stationary slip ring 3 having a second sliding surface 30. A sealing gap 4 is defined between the two slip rings 2, 3 in a known manner. The rotating slip ring 2 is connected to a rotating assembly 10, such as a bushing or the like, via a drive element 9. Reference numerals 12 and 13 denote O-rings. The stationary slip ring 3 is connected to a stationary component 11, such as a housing or the like.

The mechanical seal device 1 seals the product area 20 from the atmospheric area 21.

Within the scope of the invention, the stationary slip ring 3 is considered as a sliding element and is shown in detail in fig. 2. The stationary slip ring 3 comprises a second sliding surface 30. The second sliding surface 30 is made of a sintered material comprising a particulate carrier material 6 and a graphene-containing material 7. The particulate support material 6 is at least partially covered with the graphene-containing material 7 such that the graphene-containing material 7 at least partially surrounds the surface of the particulate support material 6. In fig. 2, the graphene-containing material 7 is illustrated as completely surrounding the particulate support material 6, but this is not essential.

As can also be seen from fig. 2, the second sliding surface 30 comprises not only the carrier material 5 coated with the graphene-containing material, but also the particulate carrier material 6 which is not coated with the graphene-containing material. In other words, the second sliding surface 30 comprises a mixture of the particulate support material 6 and the particulate support material 5 covered with the graphene-containing material.

Here, the mass ratio of the particulate support material 6 and the particulate support material 5 covered with the graphene-containing material is advantageously 80:20 to 99.5:0.5, in particular 90:10 to 99.5: 0.5.

In the embodiment shown, the particulate support material 6 consists of a ceramic material, in particular selected from the group consisting of: SiC, WC, B₄C、BN、Si₃N₄、Al₂O₃、MgO、ZrO₂And any mixtures thereof. SiC is particularly preferred due to good processability, excellent mechanical properties and also due to a reasonable price. The particulate support material 6 is in the form of ceramic particles.

The use of a ceramic particulate support material 6 has yet another advantage, which can be clearly seen in fig. 5: for example, a material mating connection 14 can be easily formed between the particulate support material 6 and the graphene-containing material 7, by which mating connection the graphene-containing material 7 is firmly bonded to the surface of the particulate support material 6. In this case, it is particularly a sinter bond characterized by high stability, thereby improving wear resistance.

Similarly, the above description can also be applied to the rotary mechanical seal 2, thereby increasing the effect achieved by the present invention.

Fig. 3 shows a longitudinal section of the bearing arrangement 40. The bearing arrangement 40 is designed as a plain bearing and comprises two radial plain bearings 41 and one axial plain bearing 42, which support a shaft 43. For the sake of completeness, fig. 4 shows a section through the same bearing arrangement 40. At least one of the shown sliding bearings 41, 42 comprises a sliding surface formed of a sintered material comprising a particulate carrier material and a graphene-containing material, as disclosed by way of example for a stationary sliding ring in fig. 2. The particulate support material is at least partially surrounded by the graphene-containing material such that the graphene-containing material at least partially surrounds a surface of the particulate support material.

As can be seen from fig. 5, the graphene-containing material 7 is composed in particular of graphene, in addition to technically unavoidable residues, which also surrounds the particulate support material 6 in the form of individual layers 7a, 7b, 7c arranged one above the other. The graphene-containing coating may advantageously comprise less than 100 layers of graphene-containing material 7, in particular less than 20 layers of graphene-containing material 7, in particular less than 12 layers of graphene-containing material 7. Therefore, the content of graphene in the particulate support material 5 covered with the graphene-containing material can be definitely controlled, and the abrasion resistance can also be controlled.

The use of the particulate support material 5 covered with the graphene-containing material allows the manufacture of sliding elements, such as mechanical seals or bearing devices, having excellent hardness, high elastic modulus and excellent wear resistance, while also having excellent tribological properties.

Fig. 6 shows a schematic process of a manufacturing process of a particulate support material 5 covered with a graphene-containing material, for example as shown in fig. 5. First, in step 100, a particulate support material 6 is dispersed in a dispersant 17. In the embodiment shown herein, SiC is used as the particulate support material 6. Aqueous, pure water or alcoholic solutions can advantageously be used as dispersing agent 17. The dispersion is carried out such that, after dispersion, the particulate carrier material 6 is dispersed in the form of individual particles in the dispersing agent 17. The use of stirrers and/or homogenizers and/or ultrasound may be advantageous here.

In step 200, a carbon source 15, in particular a carbon-containing compound advantageously selected from the group consisting of: furfuryl alcohol, glucose and mixtures thereof, since these carbon sources are formed from renewable raw materials. The carbon source 15 is a precursor of the graphene-containing material to be produced.

Subsequently, in step 300, the dispersant 17 is removed to obtain the solid substance 16, which can be performed very easily, for example, by evaporating the dispersant 17 in a rotary evaporator, and freeze-drying or the like. Drying will continue until the weight of the solid substance 16 remains constant.

The resulting solid substance 16 now comprises the particulate support material 6 and the graphene precursor disposed on the surface of the particulate support material 6. The solid matter 16 may be further processed as is, but in step 400, first crushed and then carbonized. In other words, the carbon source 15 is heat treated such that the graphene-containing material 7 at least partially, in particular completely, covers the particulate support material 6. The carbonization is carried out in particular under an inert atmosphere such as nitrogen or the like. However, other inert gases are also conceivable.

In the first temperature step, the solid matter 16 is heated to 80-180 ℃ at a heating rate of 5 ℃/min and is kept in the temperature range for 15-25 hours, and in the second temperature step, the solid matter 16 is heated to 600-1500 ℃ at a heating rate of 5 ℃/min and is kept in the temperature range for 4-8 hours.

A particulate support material 5 coated with graphene-containing material is obtained, wherein the graphene-containing material 7 covers the particulate support material 6 in the form of individual layers, i.e. at least one and advantageously less than 100 layers, in particular advantageously less than 20 layers, particularly advantageously less than 12 layers.

Fig. 7 shows a schematic illustration of a manufacturing method of a sliding element according to an embodiment of the invention, exemplified in the form of a slip ring 3. In a process step 500, a mixture of a particulate support material 6 and a particulate support material 5 at least partially, in particular completely, covered with a graphene-containing material is first produced. The particulate support material 6 is in particular a ceramic material, preferably selected from the group consisting of: SiC, WC, B₄C、BN、Si₃N₄、Al₂O₃、MgO、ZrO₂And any mixtures thereof, especially SiC. The mixing can be carried out in particular as dry mixing. Subsequently, the resulting mixture is sintered in a process step 600. The sintering process produces slip rings 3 characterized by a non-porous sintered material, thus significantly increasing the density of the slip rings 3 and also increasing the amount of wear. The slip ring 3 produced in this way is characterized by excellent stability even under severe mechanical and/or thermal shocks.

As further shown in fig. 7, the mixture obtained in the above step 500 may be applied onto a substrate 8, the substrate 8 also being in particular made of a ceramic material, in particular selected from the group consisting of: SiC, WC, B₄C、BN、Si₃N₄、Al₂O₃、MgO、ZrO₂And any mixtures thereof, in particular SiC. This allows saving material costs while maintaining good quality.

Description of the reference numerals

1 mechanical seal device

2 rotating slip ring

3 fixed slip ring

4 sealing the gap

5 coating with a particulate support material comprising a graphene-containing material

6 granular support material

7 graphene-containing material

8 base body

9 drive element

10 rotating assembly

11 outer cover

12,13 sealing ring

14 material fit connection

15 carbon source

16 solid matter

17 dispersing agent

20 product area

21 atmospheric region

29 first sliding surface

30 second sliding surface

31 back side of the plate

40 bearing device

41 radial sliding bearing

42-axial sliding bearing

43 shaft

In the X-X axial direction

100-600 processing steps