Method for producing a particulate carrier material, which is sheathed in a graphene-containing material, and a ceramic component, and ceramic component

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 ceramic component comprising: a particulate support material and a graphene-containing material, wherein the particulate support material is at least partially, coated with the graphene-containing material, a material bond is present between the particulate support material and the graphene-containing material, and said ceramic member has an electrical resistivity of from 1 Ωcm to 100 Ωcm at room temperature, further comprising a first base body, said first base body exclusively comprising said particulate support material.

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

3. The ceramic component according to claim 1, wherein the ceramic component consists of a mixture of particulate support material and particulate support material coated with graphene-containing material.

4. The ceramic component according to claim 3, 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.

5. The ceramic component according to claim 1, wherein the particulate support material consists of a ceramic material, wherein the ceramic material is 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.

6. The ceramic component according to claim 1, the graphene-containing sheathing comprising one layer up to 100 layers of graphene-containing material.

7. The ceramic component according to claim 1, the ceramic component having 6 to 8% by volume of macropores in relation to the total volume of the ceramic component.

8. A sliding member, comprising a first sliding surface, which sliding member being a ceramic component according to claim 1.

9. 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 8.

10. A bearing arrangement, especially a plain bearing or roller bearing, especially a radial plain bearing or axial plain bearing, comprising at least one sliding member according to claim 8.

11. A holder for a space craft which is a ceramic component according to claim 1.

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

13. The ceramic component according to claim 1, wherein the particulate support material consists of SiC, and/or the graphene-containing sheathing layers having one layer up to 20 layers having graphene-containing material, or the graphene-containing sheathing layers having one layer up to twelve layers of graphene-containing material.

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 ceramic component formed as 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) As a carbon source containing dopamine was used, excellent electrical conductivity of approx. 5.3×10.sup.−2 S/cm and at the same time high fracture toughness, especially greater than 5 MPa √{square root over (m)}, is achieved at room temperature.

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

(19) 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.

(20) 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.

(21) The use of particulate support material 5 coated with graphene-containing material allows for the manufacture of a ceramic component, especially 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, good electrical conductivity and high fracture toughness.

(22) 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.

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

(24) 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.

(25) 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. 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

(31) 2 rotating slide ring

(32) 3 stationary slide ring

(33) 4 sealing gap

(34) 5 particulate support material coated with a graphene-containing material

(35) 6 particulate support material

(36) 7 graphene-containing material

(37) 8 base body

(38) 9 driving member

(39) 10 rotating component

(40) 11 housing

(41) 12, 13 seal rings

(42) 14 material bond

(43) 15 carbon source

(44) 16 solid substance

(45) 17 dispersant

(46) 20 product area

(47) 21 atmosphere area

(48) 29 first sliding surface

(49) 30 second sliding surface

(50) 31 rear surface

(51) 40 bearing arrangement

(52) 41 radial slide bearing

(53) 42 axial slide bearing

(54) 43 shaft

(55) X-X axial direction

(56) 100-600 process steps