Preparation method of carbon-ceramic composite water-lubricated graphite bearing material added with nano ceramics

Abstract

The invention provides a preparation method of a nano-ceramic-added carbon-ceramic composite water-lubricated graphite bearing material, which comprises the following steps: uniformly mixing graphite powder, pitch coke powder and nano silicon dioxide to obtain a mixed material; adding molten asphalt into the mixed material, and carrying out mixing and kneading treatment; after mixing and kneading, grinding, and sieving to obtain pressed powder; the pressed powder is pressed in a cold isostatic pressing mode, and a blank is obtained; and carrying out first roasting, first asphalt impregnation, second roasting, second asphalt impregnation, third roasting, third asphalt impregnation and fourth roasting on the blank to obtain the carbon-ceramic composite water-lubricated graphite bearing material added with the high-melting-point nano ceramic. According to the preparation method, the graphite powder and the pitch coke powder are used as main materials, the pitch is used as the binder, and the high-melting-point nano ceramic material silicon dioxide is used as the additive for preparation, so that the mechanical strength and the high-temperature resistance of the water-lubricated graphite bearing material are greatly improved by adding the high-melting-point nano ceramic material.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of water-lubricated graphite bearing material preparation, in particular to a preparation method of a water-lubricated graphite bearing material added with nano ceramic carbon ceramic. BACKGROUND

[0002] Bearing is an important part in contemporary mechanical equipment, mainly used for supporting the rotating body of machinery, reducing the friction coefficient of the rotating body in the movement process, and ensuring the rotation accuracy. Common bearings include sliding bearings, rolling bearings and joint bearings. Among them, the sliding bearing refers to the bearing working under sliding friction, and the lubrication modes of the sliding bearing mainly include water lubrication and oil lubrication. Oil leakage often occurs in oil lubrication, which pollutes the environment. Compared with oil-lubricated bearings, water-lubricated bearings use water as a lubricant, have the performance advantages of green environmental protection and low energy consumption, and are widely used in fields such as ships, water pumps and water turbines.

[0003] In a nuclear power plant, the main pump is the only rotating equipment, mainly adopts water lubrication, and the quality of the water-lubricated bearing material is closely related to the safety and reliability of the nuclear pump. In view of the harsh environment of high temperature and radiation in the nuclear power plant, the water-lubricated bearing material is generally prepared from inorganic materials such as graphite or siliconized graphite, and the graphite bearing material obtained by the existing preparation method has the problems of poor flexibility, poor strength and poor wear resistance. When impacted in the use process, brittle cracking is prone to occur, thereby affecting the safe operation of the nuclear pump.

[0004] Based on this, the present application provides a preparation method of a water-lubricated graphite bearing material added with nano ceramic carbon ceramic, so as to solve the above technical problems. SUMMARY

[0005] The technical problem solved by the present application is to overcome the defects of poor mechanical strength and poor high-temperature resistance of the graphite bearing material in the prior art, and to provide a preparation method of a water-lubricated graphite bearing material added with nano ceramic carbon ceramic.

[0006] The present application solves the above technical problems by the following technical scheme:

[0007] The present application provides a preparation method of a water-lubricated graphite bearing material added with nano ceramic carbon ceramic, comprising:

[0008] Step 1, uniformly mixing graphite powder, pitch coke powder and nano silicon dioxide to obtain a mixture;

[0009] Step 2, adding molten pitch to the mixture and kneading;

[0010] Step 3, grinding after kneading, and sieving to obtain a pressed powder;

[0011] Step 4: Press the powder into a blank by cold isostatic pressing.

[0012] Step 5: After the billet undergoes a first firing, a first asphalt impregnation, a second firing, a second asphalt impregnation, a third firing, a third asphalt impregnation, and a fourth firing, a high-melting-point nano-ceramic carbon-ceramic composite water-lubricated graphite bearing material is obtained.

[0013] According to an embodiment of the present invention, in step 1,

[0014] After the graphite powder, the pitch coke powder, and the nano silica are mixed evenly, they are kneaded at room temperature for no less than 1 hour, and then heated to 85-95℃.

[0015] According to an embodiment of the present invention, in step 1,

[0016] The graphite powder content is 14wt%-17wt%, the pitch coke powder content is 78wt%-79wt%, and the nano silica content is 4wt%-8wt%.

[0017] According to one embodiment of the present invention, the graphite powder has a particle size of no more than 45 μm, the pitch coke powder has a particle size of no more than 10 μm, and the nano silica has a particle size of no more than 10 μm.

[0018] According to one embodiment of the present invention, in step 2, the molten asphalt is added to the mixture and mixed for 1 hour, then heated to 155-165°C, and kneaded at 155-165°C for no less than 2 hours.

[0019] According to an embodiment of the present invention, in step 2,

[0020] The softening point of the molten asphalt is 75-90℃, the residual carbon content is 35-43g / cm3, the ash content is not greater than 0.5%, and the mass ratio of the molten asphalt to the mixture is 1:1.

[0021] According to one embodiment of the present invention, in step 3,

[0022] The particle size of the pressed powder is no higher than 178 μm.

[0023] According to one embodiment of the present invention, in step 4,

[0024] The pressure for the cold isostatic pressing process is 150-200 MPa, and the pressure is maintained for at least 30 minutes.

[0025] According to one embodiment of the present invention, in step 5,

[0026] The conditions for the first calcination are: heating to 1100℃ at a heating rate of 2-5℃ / h and holding at that temperature for 30h;

[0027] The conditions for the second, third, and fourth roasting processes are as follows: heating to 900℃ at a heating rate of 5-10℃ / h and holding at that temperature for 10h.

[0028] According to one embodiment of the present invention, in step 5,

[0029] The treatment conditions for the first, second, and third asphalt impregnations are as follows: at a temperature of 180-300℃ and a pressure of 1-3MPa, asphalt is used as the impregnating agent for 10-20 hours.

[0030] The positive and progressive effects of this invention are as follows:

[0031] This invention relates to a method for preparing a water-lubricated graphite bearing material with added nano-ceramic carbon-ceramic composite. The method uses graphite powder and pitch coke powder as the main materials, pitch as the binder, and high-melting-point nano-ceramic material silica as an additive. By adding high-melting-point nano-ceramic material, the mechanical strength and high-temperature resistance of the water-lubricated graphite bearing material are significantly improved. Attached Figure Description

[0032] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein:

[0033] Figure 1 The process flow diagram illustrates the preparation method of the nano-ceramic carbon-ceramic composite water-lubricated graphite bearing material of this invention. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0036] ReferenceFigure 1 This invention proposes a method for preparing a water-lubricated graphite bearing material with added nano-ceramic carbon-ceramic composite, comprising:

[0037] Step 1: Mix graphite powder, pitch coke powder and nano silica evenly to obtain a mixture.

[0038] Specifically, after mixing graphite powder, pitch coke powder, and nano silica evenly, knead them at room temperature for no less than 1 hour, and then heat them to 85-95℃.

[0039] The graphite powder content is 14wt%-17wt%, the pitch coke powder content is 78wt%-79wt%, and the nano silica content is 4wt%-8wt%.

[0040] The particle size of graphite powder is no higher than 45μm, the particle size of pitch coke powder is no higher than 10μm, and the particle size of nano silica is no higher than 10μm.

[0041] Step 2: Add the molten asphalt to the mixture and knead it.

[0042] Specifically, molten asphalt is added to the mixture and mixed for 1 hour, then heated to 155-165℃ and kneaded at 155-165℃ for no less than 2 hours.

[0043] The softening point of the molten asphalt is 75-90℃, the residual carbon content is 35-43g / cm3, the ash content is not greater than 0.5%, and the mass ratio of molten asphalt to the mixture is 1:1.

[0044] Step 3: After mixing and kneading, grind the powder and sieve it to obtain pressed powder.

[0045] Specifically, the particle size of the pressed powder is no higher than 178μm.

[0046] Step 4: Press the powder using cold isostatic pressing to obtain the billet.

[0047] Specifically, the pressure for cold isostatic pressing is 150-200 MPa, and the pressure is maintained for at least 30 minutes.

[0048] Step 5: After the billet undergoes a first firing, a first asphalt impregnation, a second firing, a second asphalt impregnation, a third firing, a third asphalt impregnation, and a fourth firing, a high-melting-point nano-ceramic carbon-ceramic composite water-lubricated graphite bearing material is obtained.

[0049] Specifically, the conditions for the first roasting are: heating to 1100℃ at a heating rate of 2-5℃ / h and holding for 30h; the conditions for the second, third and fourth roastings are: heating to 900℃ at a heating rate of 5-10℃ / h and holding for 10h.

[0050] The treatment conditions for the first, second, and third asphalt impregnations are as follows: at a temperature of 180-300℃ and a pressure of 1-3MPa, asphalt is used as the impregnating agent for 10-20 hours.

[0051] Example 1

[0052] The preparation method includes the following steps:

[0053] Step 1: Add graphite powder with a particle size of less than 45μm, pitch coke powder with a particle size of less than 45μm, and nano silica with a particle size of less than 10μm to a mixing pot at a mass ratio of 17:79:4 and mix thoroughly. Knead at room temperature for no less than 1 hour, and then heat to 85-95℃ to obtain a mixture.

[0054] Step 2: Add the molten asphalt to the mixture obtained in Step 1 and mix for 1 hour. The mass ratio of molten asphalt to the mixture is 1:1. Then heat to 155-165℃ and knead at 155-165℃ for no less than 2 hours.

[0055] Step 3: After the mixing and kneading process is completed, the powder is ground in a roller mill for 1 hour and then sieved to obtain pressed powder; the particle size of the pressed powder is below 178μm.

[0056] Step 4: Press the powder obtained in Step 3 into shape using cold isostatic pressing. The cold isostatic pressing pressure is 150-200MPa, the maximum pressure is maintained for 30 minutes, and the pressing bulk density is ≥1.45g / cm3 to obtain the blank.

[0057] Step 5: The billet obtained in Step 4 undergoes a first firing, a first pitch impregnation, a second firing, a second pitch impregnation, a third firing, a third pitch impregnation, and a fourth firing to obtain the finished product. The bulk density of the finished product is ≥1.70 g / cm3, and high-melting-point nano-ceramic carbon-ceramic composite water-lubricated graphite bearing material is added.

[0058] The conditions for the first roasting treatment are: heating to 1100℃ at a heating rate of 2-5℃ / h and holding for 30h. The conditions for the second, third and fourth roasting treatments are: heating to 900℃ at a heating rate of 5-10℃ / h and holding for 10h.

[0059] The conditions for the first, second, and third asphalt impregnation treatments are as follows: at a temperature of 180-300℃ and a pressure of 1-3MPa, asphalt is used as the impregnating agent for 10-20 hours.

[0060] Example 2

[0061] The preparation method includes the following steps:

[0062] Step 1: Add graphite powder with a particle size of less than 45μm, pitch coke powder with a particle size of less than 45μm, and nano silica with a particle size of less than 10μm to a mixing pot at a mass ratio of 15:79:6 and mix thoroughly. Knead at room temperature for no less than 1 hour, and then heat to 85-95℃ to obtain the mixture.

[0063] Step 2: Add the molten asphalt to the mixture obtained in Step 1 and mix for 1 hour. The mass ratio of molten asphalt to powder is 1:1. Then heat to 155-165℃ and knead at 155-165℃ for no less than 2 hours.

[0064] Step 3: After the mixing and kneading process is completed, the powder is ground in a roller mill for 1 hour and then sieved to obtain pressed powder; the particle size of the pressed powder is below 178μm.

[0065] Step 4: Press the powder obtained in Step 3 into shape using cold isostatic pressing. The cold isostatic pressing pressure is 150-200MPa, the maximum pressure is maintained for 30 minutes, and the pressing bulk density is ≥1.45g / cm3 to obtain the blank.

[0066] Step 5: The billet obtained in Step 4 undergoes a first firing, a first pitch impregnation, a second firing, a second pitch impregnation, a third firing, a third pitch impregnation, and a fourth firing to obtain the finished product. The bulk density of the finished product is ≥1.70 g / cm3, and high-melting-point nano-ceramic carbon-ceramic composite water-lubricated graphite bearing material is added.

[0067] The conditions for the first roasting treatment are: heating to 1100℃ at a heating rate of 2-5℃ / h and holding for 30h. The conditions for the second, third and fourth roasting treatments are: heating to 900℃ at a heating rate of 5-10℃ / h and holding for 10h.

[0068] The conditions for the first, second, and third asphalt impregnation treatments are as follows: at a temperature of 180-300℃ and a pressure of 1-3MPa, asphalt is used as the impregnating agent for 10-20 hours.

[0069] Example 3

[0070] The preparation method includes the following steps:

[0071] Step 1: Add graphite powder with a particle size of less than 45μm, pitch coke powder with a particle size of less than 45μm, and nano silica with a particle size of less than 10μm to a mixing pot at a mass ratio of 14:78:8 and mix thoroughly. Knead at room temperature for no less than 1 hour; then heat to 85-95℃.

[0072] Step 2: Add the molten asphalt to the powder obtained in Step 1 and mix for 1 hour. The mass ratio of molten asphalt to powder is 1:1. Then heat to 155-165℃ and knead at 155-165℃ for no less than 2 hours.

[0073] Step 3: After the mixing and kneading process is completed, the powder is ground in a roller mill for 1 hour and then sieved to obtain pressed powder; the particle size of the pressed powder is below 178μm.

[0074] Step 4: Press the powder obtained in Step 3 into shape using cold isostatic pressing. The cold isostatic pressing pressure is 150-200 MPa, and the maximum pressure is maintained for 30 minutes. The pressed bulk density is ≥

[0075] The blank was obtained at 1.45 g / cm3.

[0076] Step 5: The billet obtained in Step 4 undergoes a first firing, a first pitch impregnation, a second firing, a second pitch impregnation, a third firing, a third pitch impregnation, and a fourth firing to obtain the finished product. The product has a bulk density ≥1.70 g / cm3 and incorporates high-melting-point nano-ceramic carbon-ceramic composite water-lubricated graphite bearing material.

[0077] The conditions for the first roasting treatment are as follows: heating to 1100℃ at a heating rate of 2-5℃ / h and holding for 30h; the conditions for the second, third, and fourth roasting treatments are as follows: heating to 900℃ at a heating rate of 5-10℃ / h and holding for 10h; the conditions for the first, second, and third asphalt impregnation treatments are as follows: impregnating with asphalt as the impregnating agent for 10-20h at a temperature of 180-300℃ and a pressure of 1-3MPa.

[0078] The properties of the products obtained in Examples 1-3 were tested, and the results are shown in the table below:

[0079]

[0080]

[0081] Examples 1 to 3 are all embodiments that satisfy the preparation process of the graphite bearing material of the present invention.

[0082] Among them, referring to the comparison of Example 1, Example 2 and Example 3 in turn, as the proportion of graphite powder decreases and the proportion of nano-silica increases, the bulk density of the product increases, the resistivity decreases, the Shore hardness increases, the flexural strength increases and the compressive strength increases.

[0083] Compared with Example 2 and Example 3, when the proportion of graphite powder and pitch coke powder in Example 3 is reduced, and the silica content is increased, the bulk density of the product increases, the resistivity decreases, the Shore hardness increases, the flexural strength decreases, and the compressive strength decreases.

[0084] In summary, the present invention provides a method for preparing water-lubricated graphite bearing materials with added nano-ceramic carbon-ceramic composites. Graphite powder and pitch coke powder are used as the main materials, pitch is used as a binder, and high-melting-point nano-ceramic material silica is used as an additive. By adding high-melting-point nano-ceramic material, the mechanical strength and high-temperature resistance of the water-lubricated graphite bearing materials are significantly improved.

[0085] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation", "connection", "joining", and "fixing" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can also refer to mechanical connections. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0086] This application uses specific terms to describe embodiments of the application. Terms such as "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0087] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a nanoceramic-carbon-carbon composite water-lubricated graphite bearing material by adding nanoceramics, characterized in that, The application relates to a high-melting-point nano-ceramic carbon-tao composite water-lubricated graphite bearing material. Step 1: uniformly mixing graphite powder, pitch coke powder and nano-silica to obtain a mixture; Step 2: adding melted pitch into the mixture and mixing and kneading; Step 3: after the mixing and kneading, grinding and sieving to obtain a pressed powder; Step 4: cold isostatic pressing the pressed powder to obtain a blank; Step 5: after the first roasting, the first pitch impregnation, the second roasting, the second pitch impregnation, the third roasting, the third pitch impregnation and the fourth roasting, the high-melting-point nano-ceramic carbon-tao composite water-lubricated graphite bearing material is obtained.

2. The method for preparing the nano-ceramic carbon-ceramic composite water-lubricated graphite bearing material according to claim 1, characterized in that, In step 1, After the graphite powder, the pitch coke powder and the nano-silica are uniformly mixed, the mixing and kneading is carried out at normal temperature for not less than 1 h, and then heating is carried out to 85-95 DEG C.

3. The method for preparing a water-lubricated graphite bearing material with added nano-ceramic carbon-ceramic composite according to claim 1, characterized in that, In step 1, The content of the graphite powder is 14wt%-17wt%, the content of the pitch coke powder is 78wt%-79wt%, and the content of the nano-silica is 4wt%-8wt%.

4. The method for preparing a water-lubricated graphite bearing material with added nano-ceramic carbon-ceramic composite according to claim 1, characterized in that, The particle size of the graphite powder is not higher than 45 microns, the particle size of the pitch coke powder is not higher than 10 microns, and the particle size of the nano-silica is not higher than 10 microns.

5. The method of manufacturing a nanoceramic-carbon-carbon composite water-lubricated graphite bearing material according to claim 1, wherein In step 2, the melted pitch is added into the mixture and mixed for 1 h, and then heating is carried out to 155-165 DEG C, and the mixing and kneading is carried out at 155-165 DEG C for not less than 2 h.

6. The method of manufacturing a nanoceramic-carbon-carbon composite water-lubricated graphite bearing material according to claim 1, wherein In step 2, The softening point of the melted pitch is 75-90 DEG C, the carbon residue is 35-43 g / cm3, the ash content is not more than 0.5%, and the mass ratio of the melted pitch to the mixture is 1:

1.

7. The method of manufacturing a nanoceramic-carbon-carbon composite water-lubricated graphite bearing material according to claim 1, wherein In step 3, The particle size of the pressed powder is not higher than 178 microns.

8. The method of manufacturing a nanoceramic-carbon-carbon composite water-lubricated graphite bearing material according to claim 1, wherein In step 4, The pressure of the cold isostatic pressing is 150-200 MPa, and the pressure is maintained for at least 30 min.

9. The method of manufacturing a nanoceramic-carbon-carbon composite water-lubricated graphite bearing material according to claim 1, wherein In step 5, The processing condition of the first roasting is heating to 1100 DEG C at a heating rate of 2-5 DEG C / h, and the temperature is maintained for 30 h; The processing conditions of the second roasting, the third roasting and the fourth roasting are heating to 900 DEG C at a heating rate of 5-10 DEG C / h, and the temperature is maintained for 10 h.

10. The method of making a nanoceramic-carbon-carbon-toughened composite water-lubricated graphite bearing material of claim 1, wherein, In step 5, The processing conditions of the first pitch impregnation, the second pitch impregnation and the third pitch impregnation are impregnation treatment for 10-20 h under the conditions of a temperature of 180-300 DEG C and a pressure of 1-3 MPa.

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