A friction pair

Abstract

The present invention discloses a friction pair, which comprises: a first sealing ring and a second sealing ring, wherein the first sealing ring is provided with a first friction plane; the second sealing ring is provided with a second friction plane; the first sealing ring and the second sealing ring are overlapped, so that the first friction plane and the second friction plane are in contact with each other; the first friction plane and the second friction plane are provided with an adhesion layer respectively, so that the first sealing ring and the second sealing ring can achieve a super-slip working state in a water-wet environment. The present invention reduces the thickness of the sealing liquid film and reduces the leakage rate of the friction pair.

Description

Technical Field

[0001] The invention relates to the field of mechanical seals, and in particular to a friction pair. Background Art

[0002] Mechanical seals are a type of rotary shaft seals and are widely used in many industries such as chemical, petroleum, textile, transportation, electricity, and agriculture.

[0003] However, during the operation of the mechanical seal, the thickness of the sealing liquid film varies according to the working state of the mechanical seal: the thickness of the sealing liquid film of the common non-contact sealing surface is about 10μm, and the thickness of the sealing liquid film of the contact seal is usually less than 1μm. Under normal circumstances, if the thickness of the sealing liquid film is too large, the sealing effect will be poor and the leakage will be large; if the thickness of the sealing liquid film is too small, the sealing surfaces will contact and wear will occur.

[0004] The thickness of the sealing liquid film is determined by the surface topography of the sealing surface. The sealing surface of existing mechanical seals usually needs to be ground and polished before assembly to make the sealing surface as smooth as possible and achieve a low roughness (Ra<0.2μm) to prevent contact, collision and wear caused by local protrusions on the sealing surface.

[0005] The lower limit of the thickness of the sealing liquid film is limited by the processing and assembly accuracy. Figure 1 As shown in the figure, the friction state of the sealing surface is in the state of "full film lubrication + local boundary lubrication". The local boundary lubrication state limits the further reduction of the thickness of the sealing liquid film. For example, in a water-lubricated mechanical seal, the thickness of the sealing liquid film cannot be less than 0.45μm between sealing surfaces with a surface roughness of Ra = 0.1μm, otherwise a large area of ​​the sealing surface will be in local contact and wear will occur. Therefore, since the thickness of the sealing liquid film cannot be further reduced, the leakage rate of the mechanical seal cannot be further reduced under the premise of ensuring that the sealing surface does not suffer large-scale wear. Summary of the invention

[0006] The purpose of the present invention is to provide a friction pair to solve the problem in the prior art that the thickness of the sealing liquid film cannot be further reduced, thereby ensuring that the sealing surface does not suffer large-area wear, resulting in the leakage rate of the mechanical seal cannot be further reduced.

[0007] In order to solve the above problems, the present invention is implemented by the following technical solutions:

[0008] A friction pair comprises: a first sealing ring and a second sealing ring, wherein the first sealing ring is provided with a first friction plane; the second sealing ring is provided with a second friction plane; the first sealing ring and the second sealing ring are overlapped so that the first friction plane and the second friction plane are in contact with each other;

[0009] The first friction plane and the second friction plane are respectively provided with adhesion layers, so that the first sealing ring and the second sealing ring can achieve a super-slip working state in a water-wet environment.

[0010] Preferably, a sealing liquid film is provided in the gap between the first friction plane and the second friction plane, and the thickness of the sealing liquid film is less than or equal to 0.1 μm.

[0011] Preferably, the friction coefficient between the first friction plane and the second friction plane is less than or equal to 0.01.

[0012] Preferably, the materials of the first sealing ring and the second sealing ring are respectively silicon carbide.

[0013] Preferably, the adhesion layer is formed by dehydration and curing of silica sol.

[0014] Preferably, an oxide layer is provided on the first friction plane and the second friction plane respectively, and the thickness of the oxide layer is 15nm-25nm.

[0015] The present invention has at least one of the following advantages:

[0016] The friction pair provided by the present invention can be applied to water-lubricated mechanical seals. Such friction pair can achieve super-slip working state in water environment, its liquid film thickness is in the order of 0.1 μm, the friction coefficient is much lower than 0.01, and there is no observable wear on the friction surface (first friction plane and second friction plane), that is, the friction pair does not have significant wear during operation. Such mechanical seal in working state can reduce the thickness of the sealing liquid film without significant wear, and greatly reduce the leakage rate of the sealing medium flowing through the sealing gap.

[0017] This solves the problem in the prior art that the thickness of the sealing liquid film cannot be further reduced, which results in the leakage rate of the mechanical seal being unable to be further reduced while ensuring that the sealing surface does not suffer large-scale wear. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the friction state of the sealing surface of the friction pair in the prior art;

[0019] Figure 2 This is a schematic diagram of the structure of the friction pair provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0020] The following is a further detailed description of a friction pair proposed by the present invention in combination with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the drawings. It should be noted that the structure, proportion, size, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical substantive significance. Any modification of the structure, change in the proportional relationship or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope of the technical content disclosed by the present invention.

[0021] like Figure 2 As shown, a friction pair includes: a first sealing ring 101 and a second sealing ring 102, wherein the first sealing ring 101 is provided with a first friction plane; the second sealing ring 102 is provided with a second friction plane; the first sealing ring 101 and the second sealing ring 102 are overlapped, so that the first friction plane and the second friction plane are in contact with each other; the first friction plane and the second friction plane are respectively provided with an adhesion layer, so that the first sealing ring 101 and the second sealing ring 102 can achieve an ultra-slip working state in a water-wet environment.

[0022] A sealing liquid film is provided in the gap between the first friction plane and the second friction plane, and the thickness of the sealing liquid film is less than or equal to 0.1 μm.

[0023] The friction coefficient between the first friction plane and the second friction plane is less than or equal to 0.01, and the friction pair does not suffer significant wear during operation.

[0024] The first sealing ring 101 and the second sealing ring 102 are respectively made of silicon carbide.

[0025] The adhesion layer is formed by dehydration and curing of silica sol.

[0026] An oxide layer is provided on the first friction plane and the second friction plane respectively, and the thickness of the oxide layer is 15nm-25nm.

[0027] The first friction plane and the second friction plane both have two microstructures. The first microstructure is a "flat surface plateau" structure 1011 with an extremely flat top plane, mainly composed of silicon carbide parent material, and an extremely thin oxide layer with a thickness of about 20nm exists on its surface. In the super-slip running state, this "flat surface plateau" structure 1011 acts as the main supporting structure to bear the normal load. The "flat surface plateau" structure 1011 of the first friction plane and the second friction plane fits relatively closely, and the gap between the two is on the order of 0.1μm.

[0028] The second microstructure is "pits or valleys filled with an adhesion layer" 1010 distributed between the first microstructure "flat surface plateau" structure 1011, and its altitude is lower than the "flat surface plateau" structure 1011. This second microstructure has a "filling" feature, the filled matrix is ​​the original surface of the silicon carbide parent material, and the adhesion layer is formed by dehydration and solidification of the silicon oxygen sol, and has a high oxygen content. In the super-slip working state, this second microstructure only bears a small amount of normal load due to its lower altitude. The silicon oxygen compound in its adhesion layer can slowly hydrolyze in an aqueous environment and generate silicate locally.

[0029] It can be understood that a mechanical seal or friction pair includes two sealing rings that fit closely on the annular surface, one of which is rigidly mounted, usually called a non-compensating ring, and the other is flexibly mounted, usually called a compensating ring. During the operation of the mechanical seal, one of the two sealing rings rotates with the shaft, while the other remains stationary. The compensating ring is pressed against the surface of the non-compensating ring by the elastic component and the static pressure of the fluid (back pressure), and there is liquid in the gap between the two sealing rings. This liquid is usually the sealed medium, forming an extremely thin liquid film.

[0030] On the other hand, the present invention also provides a method for preparing a friction pair, comprising: obtaining an original first sealing ring and a second sealing ring. After ultrasonic cleaning of the original first sealing ring and the second sealing ring, the first sealing ring and the second sealing ring are air-dried. Specifically, the cleaning liquid may be acetone or an ultrasonic cleaning device for cleaning and the ring is naturally air-dried.

[0031] The guiding liquid is dropped onto the surface of the friction surface of the first sealing ring or the second sealing ring. The first sealing ring and the second sealing ring are stacked to form a mechanical sealing assembly. At this time, the guiding liquid should fill the gap between the first sealing ring and the second sealing ring that cooperate with each other. In this embodiment, the guiding liquid is a suspension containing silicon dioxide nanoparticles, which is used as a buffer layer between the two friction surfaces. In addition, the silicon dioxide in the guiding liquid is used to form the adhesion layer.

[0032] Inject a water circuit into the mechanical seal assembly (install the mechanical seal assembly into a mechanical seal test circuit or a pump product, and inject a water circuit into the mechanical seal test circuit or the mechanical seal of a pump product), apply an initial back pressure to the mechanical seal assembly, start the rotating component to reach the rated speed, and drive the first seal ring or the second seal ring to rotate with the rotating shaft of the rotating component. Under the action of the back pressure, the first friction plane provided by the first seal ring and the second friction plane provided by the second seal ring are kept in a state of being pressed against each other. While keeping the rotating shaft rotating, increase the back pressure step by step until the fluctuation amplitude of the detected parameter is less than 0.1%, and the rotating shaft stops rotating.

[0033] The preparation method further includes: before ultrasonically cleaning the original first and second sealing rings, grinding the first surface of the first sealing ring opposite to the first friction plane to achieve a profile of 5 μm. Grinding the second surface of the second sealing ring opposite to the second friction plane to achieve a profile of 5 μm.

[0034] The initial back pressure is 0.1 MPa-0.2 MPa.

[0035] The step of gradually increasing the back pressure includes: increasing the back pressure step by step with a pressure step not higher than 25% of the target working pressure, and keeping the rotation time of the shaft for more than 2 minutes under each back pressure condition; when the back pressure reaches the maximum value, keeping the shaft rotating until the fluctuation amplitude of the detected parameter is less than 0.1%, and the shaft stops rotating.

[0036] The parameters include one of friction coefficient, leakage rate, power loss or any combination thereof.

[0037] The preparation method further includes: after the shaft stops rotating, an adhesion layer is formed on the first friction plane and the second friction plane respectively, so that the first sealing ring and the second sealing ring can achieve an ultra-slip working state in a wet environment. The adhesion layer is formed by dehydrating and solidifying the silica sol (silicon dioxide) in the guide liquid.

[0038] In summary, the friction pair provided in this embodiment can be applied to water-lubricated mechanical seals. This friction pair can achieve super-slip working state in a water environment, and its liquid film thickness is on the order of 0.1 μm, the friction coefficient is much lower than 0.01, and there is no observable wear on the friction surface (the first friction plane and the second friction plane), that is, the friction pair does not suffer significant wear during operation. This mechanical seal in a working state can reduce the thickness of the sealing liquid film without significant wear, and greatly reduce the leakage rate of the sealing medium flowing through the sealing gap. This solves the problem in the prior art that the leakage rate of the mechanical seal cannot be further reduced under the premise of ensuring that the sealing surface does not suffer large-scale wear because the thickness of the sealing liquid film cannot be further reduced.

[0039] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0040] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A friction pair, characterized in that: include: a first sealing ring and a second sealing ring, The first sealing ring is provided with a first friction plane; The second sealing ring is provided with a second friction plane; The first sealing ring is overlapped with the second sealing ring so that the first friction plane and the second friction plane are in contact with each other; The first friction plane and the second friction plane both have two microstructures. The first microstructure is a flat surface plateau structure with an oxide layer of 15nm to 25nm thickness on the surface; The second microstructure is a pit or valley structure distributed between the first microstructures and filled with an adhesion layer; the adhesion layer is formed by dehydrating and curing the silica sol, so that the first sealing ring and the second sealing ring can achieve an ultra-slip working state in a water-wet environment; A sealing liquid film is provided in the gap between the first friction plane and the second friction plane, and the thickness of the sealing liquid film is less than or equal to 0.1 μm.

2. The friction pair according to claim 1, characterized in that: The friction coefficient between the first friction plane and the second friction plane is less than or equal to 0.

01.

3. The friction pair according to claim 2, characterized in that: The first sealing ring and the second sealing ring are made of silicon carbide respectively.

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