GRAPHENE-CONTAINING SLIDE RING

Abstract

The invention relates to a slide ring of a mechanical seal arrangement, produced from a graphene-containing material.

Claims

1. Slide ring of a mechanical seal arrangement, comprising a graphene-containing material.

2. Slide ring as claimed in claim 1, wherein the graphene-containing material comprises graphene in the form of pure graphene and/or graphene oxide and/or technically reduced graphene oxide and/or functional graphene.

3. Slide ring as claimed in claim 1, wherein the material of the slide ring is a composite material, comprising a ceramic material and the graphene-containing material.

4. Slide ring as claimed in claim 3, wherein the slide ring comprises exclusively the ceramic material and the graphene-containing material.

5. Slide ring as claimed in claim 3, wherein the ceramic material and the graphene-containing material are mixed in the composite material.

6. Slide ring as claimed in claim 3, wherein the ceramic material and the graphene-containing material are evenly distributed in the slide ring.

7. Slide ring as claimed in claim 1, wherein the slide ring is a sintered component.

8. Slide ring as claimed in claim 1, wherein a weight proportion of the graphene-containing material in terms of the total weight of the slide ring is in a range of 0.1 to 10 wt. %, in particular 1 to 5 wt. %.

9. Slide ring as claimed in claim 1, wherein the slide ring has a resistivity in a range of 0.1 to 10 m.

10. Slide ring as claimed in claim 1, wherein the graphene-containing material of the slide ring is distributed in the form of graphene parts such that each graphene part has a multiplicity of individual graphene layers which are arranged directly in parallel with one another.

11. Slide ring as claimed in claim 3, wherein the ceramic material completely surrounds individual graphene constituents.

12. Slide ring as claimed in claim 1, wherein the slide ring has a slide surface and an outer side and wherein a continuous connection established from graphene-containing material is formed between the slide surface and the outer side.

13. Slide ring as claimed in claim 12, wherein the connection is formed by a graphene network consisting of graphene parts in the slide ring.

14. Slide ring as claimed in claim 1, wherein graphene-containing material is arranged on a slide surface of the slide ring.

15. Slide ring as claimed in claim 14, wherein the slide ring has a diamond coating on the slide surface.

16. Slide ring as claimed in claim 3, wherein the ceramic material is SiC or WC or silicon nitride.

17. Mechanical seal arrangement having a rotating slide ring and a stationary slide ring, wherein at least one of the slide rings is a slide ring as claimed in claim 1.

Description

[0020] Preferred exemplified embodiments of the invention will be described in detail hereinafter with reference to the accompanying drawing. Like or functionally identical parts are designated in the drawing in each case by like reference signs. In the drawing:

[0021] FIG. 1 shows a schematic sectional view of a mechanical seal having a slide ring in accordance with the invention in accordance with a first exemplified embodiment of the invention;

[0022] FIG. 2 shows a schematic sectional view of the slide ring shown in FIG. 1; and

[0023] FIG. 3 shows a schematic view of a crack extending through the slide ring, and

[0024] FIG. 4 shows a schematic sectional view of a slide ring in accordance with a second exemplified embodiment of the invention.

[0025] FIG. 1 schematically shows a mechanical seal arrangement 1 having a rotating slide ring 2 and a stationary slide ring 3. A sealing gap 4 is defined between the two slide rings 2, 3 in a known manner. The rotating slide ring 2 is connected to a rotating component 10, e.g. a shaft sleeve or the like, via an entrainment element 9. References signs 12 and 13 designate O-rings. The stationary slide ring 3 is connected to a stationary component 11, such as e.g. a housing or the like.

[0026] The mechanical seal arrangement 1 seals a product region 20 from an atmosphere region 21.

[0027] The stationary slide ring 3 is shown in detail in FIG. 2. The stationary slide ring 2 is produced from a composite material which comprises a ceramic material 5 and a graphene-containing material 6. The graphene-containing material 6 is evenly distributed in the composite material of the slide ring. The graphene-containing material can be pure graphene and/or graphene oxide and/or technically reduced graphene oxide and/or functional graphene, in which at least one other chemical molecule is attached, or can be any combination of the aforementioned materials.

[0028] As illustrated in the detail of FIG. 2, the graphene-containing material 6 is arranged, in the form of a multiplicity of graphene parts, in the ceramic material 5. The graphene parts comprise in each case a multiplicity of graphene layers which are arranged in parallel with one another. The number of graphene layers per graphene part is between 100 and 1000. The individual graphene parts can contact one another within the composite material or they are completely surrounded by crystals of the ceramic material 5, so that there is no contact with adjacent graphene parts. The ceramic material is preferably SiC.

[0029] The stationary slide ring 3 of this exemplified embodiment is a sintered component, wherein, in order to produce the slide ring, a ceramic powder is mixed with the graphene-containing material in a first step, in order to provide a sintering powder. In this case, graphene-containing material is admixed in a range of 0.1 to 10 wt. % and in particular 1 to 5 wt. % of the total weight of the sintering powder. In a next step, a green body is formed from the sintered powder mixture which is subsequently sintered.

[0030] The admixing of graphene-containing material to the ceramic sintering material produces against expectation a slide ring consisting of a composite material which offers unexpected advantages whilst retaining its strength. In addition to a significantly improved, particularly low resistivity of up to 0.1 m, the fracture toughness of the material of the slide ring is also considerably improved.

[0031] In the case of typical slide rings consisting of ceramic material, such as e.g. SiC, cracks can occur after a certain operating period and frequently extend, starting from the slide surface, through the entire slide ring. Such damage can be substantially avoided in the case of a slide ring in accordance with the invention having a graphene proportion. It has proven to be the case that the graphene parts prevent crack growth of a crack 8 through the entire component. The cracks typically occur substantially perpendicularly with respect to the slide surface of the slide ring and then extend in an axial direction X-X through the entire slide ring. The graphene parts which consist of a multiplicity of mutually parallel individual graphene layers significantly retard the crack progress rate. If a crack 8 impinges upon a graphene part consisting of a multiplicity of graphene layers, the graphene layers do not all crack at the same time but rather individually. As a result, a propagation rate of a crack 8 through the component is significantly reduced. Therefore, the slide ring in accordance with the invention has a considerably longer service life than the conventional slide rings. Crack formation is indicated schematically in FIG. 3.

[0032] In the case of a slide ring consisting of pure SiC, the crack would run along the grain boundaries of the ceramic material through the entire component in an extremely short amount of time.

[0033] As is also evident in FIG. 2, some graphene parts are arranged in the slide ring such that they are at least partially exposed on the surface of the slide surface 30. This offers further advantages in terms of a reduced coefficient of friction, in particular in the event of dry operation of the mechanical seal arrangement. In this case, during dry operation, small segments of the graphene parts are presumably broken off and form a type of lubricant. Therefore, an improved dry running property of such a mechanical seal arrangement can also be achieved. In a particularly preferred manner, the stationary slide ring 3 and also the rotating slide ring 2 are produced from the material in accordance with the invention, comprising a ceramic material 5 and graphene-containing material 6.

[0034] FIG. 4 shows a slide ring 3 in accordance with a second exemplified embodiment of the invention. In contrast to the first exemplified embodiment, the second exemplified embodiment comprises an arrangement of the graphene-containing material 6 such that individual graphene parts form a continuous connection through the slide ring from the slide surface 30 to a rear side 31 and to further outer sides of the slide ring. By way of example, FIG. 4 also illustrates a continuous graphene connection to a radial outer side 32. Mutually adjacent graphene parts contact one another and are each arranged at different angles with respect to one another. In a particularly preferred manner, the continuous connection from the slide surface 30 to the rear side 31 or the outer sides is formed as a network-like structure 7. Therefore, many direct connection paths are produced by a wide variety of graphene parts, which are arranged in the manner of a network, from the slide surface 30 to the rear side 31 or further outer sides. Therefore, in particular the electrical conductivity of the slide ring 3 can be significantly improved. The reason for this resides in the fact that the graphene has a considerably higher electrical conductivity than the ceramic material, e.g. SiC. The improved electrical conductivity can be used specifically in conjunction with a current circuit across the slide ring or can also be used to reduce electrostatic charges on the slide surface 30.

LIST OF REFERENCE SIGNS

[0035] 1 mechanical seal arrangement [0036] 2 rotating slide ring [0037] 3 stationary slide ring [0038] 4 sealing gap [0039] 5 ceramic material [0040] 6 graphene-containing material [0041] 7 graphene network [0042] 8 crack [0043] 9 entrainment element [0044] 10 rotating component [0045] 11 housing [0046] 12, 13 sealing rings [0047] 20 product region [0048] 21 atmosphere region [0049] 30 slide surface [0050] 31 rear side [0051] X-X axial direction