Method for producing a particulate carrier material, which is sheathed in a graphene-containing material, and a slide element, and slide element, slip ring seal and bearing arrangement

Abstract

The invention relates to a sliding member having a first sliding surface, wherein the first sliding surface (29) comprises a particulate support material (6) and a graphene-containing material (7), wherein the particulate support material (6) is at least partially coated with the graphene-containing material (7), and wherein a material bond (14) is present between the particulate support material (6) and the graphene-containing material (7).

Claims

1. A sliding member comprising a first sliding surface, the first sliding surface comprising a particulate support material and a graphene-containing material, the particulate support material being at least partially coated with the graphene-containing material, and a material bond being present between the particulate support material and the graphene-containing material, wherein the first sliding surface has 6 to 8% by volume of macropores in relation to the total volume of the first sliding surface.

2. The sliding member according to claim 1, wherein the particulate support material is completely coated with the graphene-containing material.

3. The sliding member according to claim 2, further comprising a first base body associated with the first siding surface, said first base body consisting of said particulate support material.

4. The sliding member according to claim 1, wherein the first sliding surface consists of a mixture of particulate support material and particulate support material coated with graphene-containing material.

5. The sliding member according to claim 4, wherein a mass ratio of particulate support material and particulate support material coated with graphene-containing material is 80:20 to 99.5:0.5.

6. The sliding member according to claim 1, wherein the particulate support material consists of a ceramic material selected from the group consisting of: SiC, WC, B.sub.4C, BN, Si.sub.3N.sub.4, Al.sub.2O.sub.3, MgO, ZrO.sub.2 and mixtures thereof.

7. The sliding member according to claim 1, the graphene-containing sheathing comprising a coating of up to 100 layers of graphene-containing material.

8. A mechanical seal comprising: a rotating first slide ring having a first sliding surface and a stationary second slide ring having a second sliding surface defining a sealing gap therebetween, the first slide ring and/or the second slide ring being a sliding member according to claim 1.

9. A bearing arrangement comprising at least one sliding member according to claim 1.

10. The sliding member according to claim 4, wherein a mass ratio of particulate support material and particulate support material coated with graphene-containing material is 90:10 to 99.5:0.5.

11. The sliding member according to claim 1, wherein the graphene-containing sheathing comprises a coating of up to 20 layers of graphene-containing material.

12. The sliding member according to claim 1, wherein the graphene-containing sheathing comprises a coating of up to 12 layers of graphene-containing material.

13. The bearing arrangement according to claim 9, wherein the bearing is selected from the group consisting of: a slide bearing, a roller bearing, a radial slide bearing and an axial slide bearing.

Description

(1) In the following, preferred example embodiments of the invention will be described in detail while making reference to the accompanying drawing. In the drawing, equal or functionally equal parts are identified with the same reference numbers, wherein:

(2) FIG. 1 is a schematic sectional view of a mechanical seal according to a first example embodiment of the invention;

(3) FIG. 2 is a schematic sectional view of the second slide ring shown in FIG. 1;

(4) FIG. 3 is a schematic longitudinal view of a bearing arrangement according to a second example embodiment of the invention;

(5) FIG. 4 is a cross-section of the bearing arrangement shown in FIG. 3;

(6) FIG. 5 is a schematic sectional view of a particulate support material coated with graphene-containing material of the stationary slide ring shown in FIG. 2;

(7) FIG. 6 is a schematic representation of a method for the manufacture of particulate support material coated with graphene-containing material according to an embodiment of the invention;

(8) FIG. 7 is a schematic representation of a method for the manufacture of a sliding member according to an embodiment of the invention.

(9) The present invention is described in detail by example embodiments. The figures only show the essential features of the present invention, all other features are omitted for the sake of clarity. Furthermore, equal reference numbers identify equal members.

(10) FIG. 1 schematically shows a mechanical seal arrangement 1 comprising a rotating slide ring 2 having a first sliding surface 29, and a stationary slide ring 3 having a second sliding surface 30. A sealing gap 4 is defined between the two slide rings 2, 3 in a known manner. The rotating seal ring 2 is connected to a rotating component 10, such as a shaft sleeve or the like, via a driving member 9. The reference numbers 12 and 13 identify O-rings. The stationary seal ring 3 is connected to a stationary component 11, such as a housing or the like.

(11) The mechanical seal arrangement 1 seals a product area 20 from an atmosphere area 21.

(12) Within the scope of the invention, the stationary slide ring 3 is to be regarded as a sliding member and is shown in detail in FIG. 2. The stationary slide ring 3 includes the second sliding surface 30. The second sliding surface 30 is made of a sintered material comprising a particulate support material 6 and a graphene containing material 7. The particulate support material 6 is at least partially coated with the graphene-containing material 7, such that the graphene-containing material 7 at least sectionally surrounds a surface of the particulate support material 6. In FIG. 2, the graphene-containing material 7 is exemplified as completely surrounding the particulate support material 6, but this is not essential.

(13) As it may also be seen in FIG. 2, the second sliding surface 30 not only comprises a support material 5 coated with graphene-containing material, but also comprises particulate support material 6 not coated with graphene-containing material. In other words, the second sliding surface 30 comprises a mixture of particulate support material 6 and particulate support material 5 coated with graphene-containing material.

(14) Herein, a mass ratio of particulate support material 6 and particulate support material 5 coated with graphene-containing material advantageously is 80:20 to 99.5:0.5 and especially 90:10 to 99.5:0.5.

(15) In the embodiment shown, the particulate support material 6 consists of a ceramic material, especially selected from the group consisting of: SiC, WC, B.sub.4C, BN, Si.sub.3N.sub.4, Al.sub.2O.sub.3, MgO, ZrO.sub.2 and any mixtures thereof. SiC is particularly preferred because of good processability, excellent mechanical properties and also because of reasonable price thereof. The particulate support material 6 is in the form of ceramic grains.

(16) Using ceramic particulate support material 6 still has another advantage, which may clearly be seen in FIG. 5: for example, a material bond 14 may easily be formed between the particulate support material 6 and the graphene-containing material 7, through which bond the graphene-containing material 7 is firmly bonded to the surface of the particulate support material 6. In this case, it is especially a sinter bond characterized by high stability, thus increasing abrasion resistance.

(17) Analogously, the above-mentioned explications may as well be applied to the rotating mechanical seal 2, thus increasing the effects achieved by the invention.

(18) FIG. 3 shows a bearing arrangement 40 in longitudinal section. The bearing arrangement 40 is designed as a slide bearing and comprises two radial slide bearings 41 and one axial slide bearing 42, which support a shaft 43. For the sake of completeness, FIG. 4 shows the same bearing arrangement 40 in cross-section. At least one of the slide bearings 41, 42 shown comprises a sliding surface formed from a sintered material comprising a particulate support material and a graphene-containing material as is disclosed by way of example for the stationary slide 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 sectionally surrounds a surface of the particulate support material.

(19) Moreover, as it may be seen from FIG. 5, the graphene-containing material 7, which especially consists of graphene except for technically unavoidable residues, surrounds the particulate support material 6 in the form of individual layers 7a, 7b, 7c, which are arranged on top of each other. The graphene-containing coating may advantageously comprise a coating of up to 100 layers, especially a coating of up to 20 layers and especially a coating of up to twelve layers of graphene-containing material 7. Thus, a content of graphene in the particulate support material 5 coated with graphene-containing material may specifically be controlled, as may the abrasion resistance.

(20) The use of particulate support material 5 coated with graphene-containing material allows for the manufacture of a sliding member, such as a mechanical seal or bearing arrangement, having excellent hardness, high modulus of elasticity and excellent abrasion resistance, while, at the same time, also having excellent tribological properties.

(21) FIG. 6 shows a schematic course of the procedure in the manufacture of particulate support material 5 coated with graphene-containing material, as shown, for example, 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 a particulate support material 6. An aqueous solution, pure water or an alcoholic solution may advantageously be used as a dispersant 17. Dispersing is performed such that, after dispersion, the particulate support material 6 is distributed in the dispersant 17 in the form of individual particles. Herein use of a stirrer and/or a homogenizer and/or ultrasound may be of advantage.

(22) In step 200, a carbon source 15 is added, specifically a carbonaceous compound advantageously selected from the group consisting of: Furfuryl alcohol, glucose and mixtures thereof, as these carbon sources are formed from renewable feedstock. The carbon source 15 is a precursor of the graphene-containing material to be produced.

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

(24) Now, the solid substance 16 obtained comprises the particulate support material 6 and the graphene precursor arranged on a surface of the particulate support material 6.

(25) The solid substance 16 may be processed further as it is, but in step 400, is first comminuted and then carbonized. In other words, the carbon source 15 is thermally treated such that the graphene-containing material 7, at least partially, especially completely, covers the particulate support material 6. Carbonization especially is done under an inert gas atmosphere, such as nitrogen. However, other inert gases are also conceivable.

(26) In a first temperature step, the solid substance 16 is heated to 80 to 180° C. at a heating rate of 5° C./min and will be held at that temperature range for 15 to 25 hours, and in a second temperature step, the solid substance 16 is heated to 600 to 1500° C. at a heating rate of 5° C./min and is held at that temperature range for 4 to 8 hours.

(27) A particulate support material 5 coated with graphene-containing material is obtained, wherein the graphene-containing material 7 coats the particulate support material 6 in the form of individual layers, i.e. at least one layer and advantageously up to 100 layers, especially advantageously up to 20 layers and especially advantageously up to 12 layers.

(28) FIG. 7 shows a schematic representation of a method for the manufacture of a sliding member according to an embodiment of the invention, which is exemplified in the form of a slide ring 3. In process step 500, a mixture of a particulate support material 6 and a particulate support material 5 at least partially, especially completely, coated with a graphene-containing material is first produced. The particulate support material 6 especially is a ceramic material, preferably selected from the group consisting of: SiC, WC, B.sub.4C, BN, Si.sub.3N.sub.4, Al.sub.2O.sub.3, MgO, ZrO.sub.2 and any mixtures thereof, and especially SiC. Mixing especially may be performed as dry mixing. Subsequently, the resulting mixture is sintered in process step 600. The sintering process produces a slide ring 3 characterized by a pore-free sinter material, thus significantly increasing the density of the slide ring 3 and also increasing the abrasion volume. The slide ring 3 produced in this way is characterized by excellent stability, even under heavy mechanical and/or thermal impacts.

(29) As it is further shown in FIG. 7, the mixture obtained in step 500 above may be applied to a base body 8, the base body 8 also being especially made of a ceramic material, especially selected from the group consisting of: SiC, WC, B.sub.4C, BN, Si.sub.3N.sub.4, Al.sub.2O.sub.3, MgO, ZrO.sub.2 and any mixtures thereof, and especially SiC. This allows material costs to be saved while maintaining good quality.

LIST OF REFERENCE NUMBERS

(30) 1 mechanical seal arrangement 2 rotating slide ring 3 stationary slide ring 4 sealing gap 5 particulate support material coated with a graphene-containing material 6 particulate support material 7 graphene-containing material 8 base body 9 driving member 10 rotating component 11 housing 12, 13 seal rings 14 material bond 15 carbon source 16 solid substance 17 dispersant 20 product area 21 atmosphere area 29 first sliding surface 30 second sliding surface 31 rear surface 40 bearing arrangement 41 radial slide bearing 42 axial slide bearing 43 shaft X-X axial direction 100-600 process steps