Preparation process of porous graphite with variable pore diameter

Abstract

The invention is applied to the technical field of graphite, and particularly relates to a preparation process of porous graphite with variable pore diameters. The experimental raw materials comprise formaldehyde, phenol, ammonia water and porous graphite. The preparation method comprises the following steps: mixing formaldehyde and phenol, stirring, and adding ammonia water to obtain the thermosetting phenolic resin. And finally, pressurizing and heating are performed, so that the thermosetting phenolic resin is adhered to the inner walls of pores of the porous graphite to different degrees along with the reduction of the pressure in the porous graphite, and a trumpet-shaped limiting layer is formed. After the graphite is treated by the process, the pore diameter of the graphite is reduced to 20-40 [mu] m from the initial 50-100 [mu] m. The method has the following advantages: firstly, experimental raw materials are easy to obtain, and experimental operation is simple and convenient; secondly, porous graphite with variable pore diameters can be obtained after the method is used.

Description

Technical Field

[0001] The invention is used in the field of graphite technology, and in particular relates to a preparation process for porous graphite pores with variable pore diameters. Background Art

[0002] Porous graphite, as a high-performance material, contains pores of different diameters. These pores play a very important role in the air static bearing system. However, when there are pores with too large diameters in porous graphite, it will induce the air hammer phenomenon, causing the spindle to vibrate and deviate when rotating at high speed, which will adversely affect the surface quality of the processed product, such as reduced precision and increased surface roughness. Uniform pore size distribution reduces air flow disturbance and can effectively reduce the air hammer effect.

[0003] There is still a lack of effective methods for regulating the diameter of large pores in porous graphite. Traditional processing methods often make it difficult to accurately adjust the pore diameter inside porous graphite while ensuring the overall performance of porous graphite materials. The traditional impregnation method uses a single pressure impregnation method, which makes it difficult to achieve gradient control of pore diameter, and the penetration depth of the impregnated material is insufficient, resulting in limited pore size reduction (only 20% to 30%).

[0004] In view of the key influence of porous graphite pore diameter on its application performance and the gap in the current technology field, it is particularly urgent to develop a new preparation process that can not only maintain the original excellent properties of graphite but also flexibly adjust its pore diameter. Summary of the invention

[0005] The present invention provides a novel preparation process for porous graphite pores with variable pore diameters. The raw materials include formaldehyde, phenol, ammonia water and porous graphite, and are matched with air compressors, impregnation tanks and other equipment to achieve the purpose of changing the pore diameters of porous graphite.

[0006] The principle of the present invention is that different pressures are required when thermosetting phenolic resin enters pores of different diameters, and different graphite pore diameter changes can be obtained by using different pressures. During the pressurized impregnation process of thermosetting phenolic resin, due to the difference in resistance of pores of different diameters inside porous graphite, thermosetting phenolic resin will preferentially fill large pores in the high-pressure area, and finally the change of pore diameter is achieved by applying different pressures during processing.

[0007] The technical solution of the present invention to solve the above problem is: a preparation process of porous graphite pores with variable pore diameters. Its components are:

[0008] The molar mass ratio of formaldehyde to phenol is 1.2:1, and the ratio of ammonia water to phenol is 0.05:1.

[0009] In the present invention, formaldehyde and phenol are raw materials for producing thermosetting phenolic resin.

[0010] Adding methyl ricinoleate plasticizer to thermosetting phenolic resin can improve the wetting ability of thermosetting phenolic resin and make the thermosetting phenolic resin have better molding properties.

[0011] A novel graphite pore variable diameter preparation process comprises the following steps in sequence:

[0012] S1. Place formaldehyde and phenol in a reaction kettle at a molar mass ratio of 1.2:1, and stir at 40°C for 20 minutes to mix them evenly;

[0013] S2, adding ammonia water in a molar mass ratio of ammonia water to phenol of 0.05:1, stirring and heating the mixture from 40°C to 80°C;

[0014] S3, stop stirring, raise the temperature to 104°C, continue stirring and reflux at 104°C;

[0015] S4, water and thermosetting phenolic resin are separated, and the mass ratio of water to thermosetting phenolic resin is 4.8:1 to 5.2:1;

[0016] S5, vacuum dehydrating the obtained mixture until the water content is ≤0.5% (mass fraction), and cooling according to the operating specifications after the quality inspection is qualified;

[0017] S6. Place the porous graphite sample into an impregnation tank, raise the temperature to 120° C., and dry the water again;

[0018] S7, evacuate, stop heating, the negative pressure in the tank is 0.008-0.010Mpa, and cool the product to 35°C;

[0019] S8. Add thermosetting phenolic resin and methyl ricinoleate plasticizer in a vacuum state. The amount of methyl ricinoleate added is 3% to 5% of the total mass of the thermosetting phenolic resin. The liquid level of the thermosetting phenolic resin should be about 15±2mm higher than the product after the pressurization is completed, and then stop vacuuming;

[0020] S9, pressurizing to 0.6Mpa for 3-4 hours, and then pressing the thermosetting phenolic resin back into the storage tank;

[0021] S10, leaving the impregnated graphite for 4 hours, applying an air pressure of 0.2 MPa to one side of the selected porous graphite, the ventilation time is 0.5 hours, and then leaving it to stand for another hour;

[0022] S11. Raise the pressure of the selected surface of the porous graphite to 1 MPa, evacuate the other side, and raise the temperature to 130°C and keep it for 3 hours, then take it out after cooling.

[0023] The advantages of the present invention are:

[0024] First: The raw materials are simple and easy to obtain. They are common basic materials in chemical production, with wide access channels and low cost.

[0025] Second: It is easy to operate, easy to understand and execute, without complicated techniques or tedious pretreatment. The reaction conditions are mild, which reduces the difficulty of operation and safety risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of gas introduction

[0027] Figure 2 Gas inlet profile

[0028] Figure 3 Aperture change diagram

[0029] Figure 4 Process flow chart DETAILED DESCRIPTION

[0030] The experiment must be carried out in a fume hood, and the operator must wear a gas mask and acid- and alkali-resistant gloves.

[0031] A preparation process for porous graphite pores with variable pore diameters, specifically comprising the following steps:

[0032] S1. Place formaldehyde and phenol in a reaction kettle at a molar mass ratio of 1.2:1, and stir at 40°C for 20 minutes to mix them evenly;

[0033] S2, adding ammonia water in a molar mass ratio of ammonia water to phenol of 0.05:1, stirring and heating the mixture from 40°C to 80°C;

[0034] S3, stop stirring, raise the temperature to 104°C, continue stirring and reflux at 104°C;

[0035] S4, water and thermosetting phenolic resin are separated, and the mass ratio of water to thermosetting phenolic resin is 4.8:1 to 5.2:1;

[0036] S5, vacuum dehydrating the obtained mixture until the water content is ≤0.5% (mass fraction), and cooling according to the operating specifications after the quality inspection is qualified;

[0037] S6. Place the porous graphite sample into an impregnation tank, raise the temperature to 120° C., and dry the water again;

[0038] S7, evacuate, stop heating, the negative pressure in the tank is 0.008-0.010Mpa, and cool the product to 35°C;

[0039] S8. Add thermosetting phenolic resin and methyl ricinoleate plasticizer in a vacuum state. The amount of methyl ricinoleate added is 3% to 5% of the total mass of the thermosetting phenolic resin. The liquid level of the thermosetting phenolic resin should be about 15±2mm higher than the product after the pressurization is completed, and then stop vacuuming;

[0040] S9, pressurizing to 0.6Mpa for 3-4 hours, and then pressing the thermosetting phenolic resin back into the storage tank;

[0041] S10, leaving the impregnated graphite for 4 hours, applying an air pressure of 0.2 MPa to one side of the porous graphite, the ventilation time is 0.5 hours, and then leaving it to stand for another hour;

[0042] S11. Raise the pressure of the selected surface of the porous graphite to 1 MPa, evacuate the other side, and raise the temperature to 130°C and keep it for 3 hours, then take it out after cooling.

[0043] The above describes the implementation modes of the present invention in detail in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes. Various modifications can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present invention. These are all modifications without creativity and are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A process for preparing porous graphite with variable pore size, comprising the following steps: S1. Place formaldehyde and phenol in a reaction kettle at a molar mass ratio of 1.2:1, and stir at 40°C for 20 minutes to mix them evenly; S2, adding ammonia water in a molar mass ratio of ammonia water to phenol of 0.05:1, stirring and heating the mixture from 40°C to 80°C; S3, stop stirring, raise the temperature to 104°C, continue stirring and reflux at 104°C; S4, water and thermosetting phenolic resin are separated, and the mass ratio of water to thermosetting phenolic resin is 4.8:1 to 5.2:1; S5, vacuum dehydrating the obtained mixture until the water content is ≤0.5% (mass fraction), and cooling according to the operating specifications after the quality inspection is qualified; S6. Place the porous graphite sample into an impregnation tank, raise the temperature to 120° C., and dry the water again; S7, evacuate, stop heating, the negative pressure in the tank is 0.008-0.010Mpa, and cool the product to 35°C; S8. Add thermosetting phenolic resin and methyl ricinoleate plasticizer in a vacuum state. The amount of methyl ricinoleate added is 3% to 5% of the total mass of the thermosetting phenolic resin. The liquid level of the thermosetting phenolic resin should be about 15±2mm higher than the product after the pressurization is completed, and then stop vacuuming; S9, pressurizing to 0.6Mpa for 3-4 hours, and then pressing the thermosetting phenolic resin back into the storage tank; S10, leaving the impregnated graphite for 4 hours, applying an air pressure of 0.2 MPa to one side of the selected porous graphite, the ventilation time is 0.5 hours, and then leaving it to stand for another hour; S11. Raise the pressure of the selected surface of the porous graphite to 1 MPa, evacuate the other side, and raise the temperature to 130°C and keep it for 3 hours, then take it out after cooling.

2. A process for preparing porous graphite with variable pore size according to claim 1, characterized in that The molar mass ratio of formaldehyde to phenol is 1.2:1, and the molar mass ratio of ammonia water to phenol is 0.05:

1.

3. A process for preparing porous graphite with variable pore size according to claim 1, characterized in that The impregnated graphite was placed for 4 hours, and an air pressure of 0.2 MPa was applied to one side of the porous graphite for 0.5 hours, and the mixture was allowed to stand for another hour.

4. A process for preparing porous graphite with variable pore size according to claim 1, characterized in that The selected pressure of the porous graphite is raised to 1Mpa, and the other side is evacuated. At the same time, the temperature is raised to 130℃ and kept for 3 hours, and then taken out after cooling.

5. A process for preparing porous graphite with variable pore size, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 4.

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