Preparation method of high-adhesion, high-conductivity and low-shrinkage glassy carbon coating

Abstract

The invention discloses a preparation method of a high-adhesion, high-conductivity and low-shrinkage glassy carbon coating, which is characterized in that bismaleimide, boric acid and graphene oxide are added into furan resin, so that the conductivity of the furan resin is enhanced, and the shrinkage of the furan resin is inhibited. And vacuumizing and high-pressure repeated dipping are adopted, so that the low-molecular-weight polymer can better enter pores in the graphite piece. And the modified furan resin on the surface of the graphite piece and the low-molecular-weight polyimide in the graphite piece are crosslinked, so that continuous glassy carbon films are formed inside and outside the graphite piece. The problem that the service life of the graphite crucible cannot be guaranteed due to the fact that the surface of the graphite crucible is oxidized at high temperature at present is solved, and the modified furan resin solution is high in residual carbon rate and small in contractibility, can bear high heating and cooling rate in the heat treatment process and is not prone to cracking.

Description

Technical Field

[0001] The present invention belongs to the technical field of glassy carbon coating processing, and particularly relates to a preparation method of a glassy carbon coating with high adhesion, high conductivity and low shrinkage. Background Art

[0002] Graphite crucibles have been widely used in the fields of metallurgy, casting, chemical engineering, etc. due to their excellent high-temperature resistance and corrosion resistance. Graphite crucibles are mainly made of graphite, which is an allotrope of carbon and has good chemical stability and thermal conductivity. However, graphite crucibles still face some challenges in high-temperature and corrosive environments.

[0003] Although graphite has strong corrosion resistance to acid and alkali solutions, during long-term use, corrosive media may still penetrate into the interior of the graphite crucible, leading to the deterioration of the material structure. Existing technologies fill glassy carbon in the pores of graphite crucibles, but they cannot protect the surface of the graphite crucible. The surface of the graphite crucible will be oxidized at high temperatures, and the service life of the graphite crucible still cannot be guaranteed. Summary of the Invention

[0004] Aiming at the problem that it is difficult for glassy carbon to protect the surface of graphite parts in the prior art, the present invention provides a preparation method of a glassy carbon coating with high adhesion, high conductivity and low shrinkage. On the one hand, a low-molecular-weight polymer infiltrated into the interior of the graphite part is connected with the furan resin on the surface to form a rivet structure. On the other hand, a graphene-reinforced network skeleton is used as the low-shrinkage glassy carbon coating to effectively protect the graphite part body. In addition, the CP structure formed by boric acid and carbon and the graphene skeleton can effectively ensure the conductivity of the coating.

[0005] The specific technical solution of the present invention is as follows: (1) Mix furan resin, bismaleimide, 1 wt% aqueous graphite oxide dispersion, and boric acid in a mass ratio of 79:15:1:5 to form a modified furan resin solution; the added bismaleimide crosslinks with the furan resin to form a network structure, and in-situ doped graphene oxide exists in the crosslinked network, forming a high-strength network skeleton, which effectively inhibits the shrinkage during the heat treatment process of the furan resin and avoids cracking of the prepared glassy carbon. Moreover, the graphite support skeleton has good conductivity, which can improve the conductivity of the glassy carbon.

[0006] (2) Defoam the modified furan resin solution; (3) Place the graphite part in a pressure tank and pour in a 5 wt% - 10 wt% aqueous solution of polyimide with a molecular weight of 5000 - 10000; (4) Control the pressure of the pressure tank according to the following procedure: (4.1) - 3 mpa for 10 min; (4.2) +3 mpa for 10 min; (4.3) -6 mpa for 10 min; (4.4) +6 mpa for 10 min; (4.5) -10 mpa for 10 min; (4.6) +10 mpa for 10 min to obtain graphite piece 1; Evacuating can remove the air in the pores inside the graphite plate, enabling low-molecular-weight polymers to enter the pores for filling. High pressure can squeeze the polymers into smaller pores. Repeating such operations can ensure that the polymer molecules completely fill the pores of the graphite piece.

[0007] (5) Rotate graphite piece 1 on a spin coater to uniformly apply polyimide on the surface to obtain graphite piece 2; (6) Pour the degassed modified furan resin solution into an atomizing spray gun and uniformly spray it onto graphite piece 2 to obtain graphite piece 3; (7) Heat-treat graphite piece 3 to obtain a graphite piece with a high-adhesion, high-conductivity, and low-shrinkage glassy carbon coating.

[0008] Preferably, the thickness of the high-adhesion, high-conductivity, and low-shrinkage glassy carbon coating is 5 - 10 μm.

[0009] Further, before putting the graphite piece in step 3 into the pressure tank, rinse its surface with ethanol until there are no powder particles, and bake it dry under a baking lamp.

[0010] Further, the time of the baking lamp is 3 - 5 min.

[0011] Further, the method of uniformity in step 5 is to rotate on a spin coater at a rotation speed of 1000 r / min for 5 min.

[0012] Further, during the atomizing spraying in step 6, place graphite piece 2 on the spin coater and rotate it at 4000 r / min.

[0013] Further, the heat treatment in step 7 is to heat from room temperature to 500 °C at a rate of 5 °C / min, hold for 1 h, then increase the temperature at a rate of 10 °C / min to 600 °C - 800 °C and hold for 1 h, and then cool to room temperature at a rate of 2 °C / min.

[0014] The low-molecular-weight polymer inside the graphite plate is connected to the furan resin on the surface to form a rivet structure, so the prepared glassy carbon coating has strong adhesion. Bismaleimide increases the crosslinking density of the furan resin, increases its char yield, and reduces the volume shrinkage of the formed glassy carbon. Boric acid improves the electrical conductivity of the glassy carbon. The added graphene oxide can form a support skeleton with good conductivity. The skeleton can inhibit the shrinkage of the furan resin during the heat treatment process and also increase the electrical conductivity of the glassy carbon.

[0015] In addition, by using repeated impregnation under vacuum + high pressure, the low-molecular-weight polymer can better enter the internal pores of the graphite part. The modified furan resin on the surface of the graphite part crosslinks with the low-molecular-weight polyimide inside, forming a continuous glassy carbon film inside and outside the graphite part. Preferably, the thickness of the glassy carbon film is 5 - 10 μm.

[0016] In some embodiments of the present invention, the defoaming method described in step 2 can be defoaming by mixing evenly in a planetary centrifugal mixer, with a mixing mode of 1000 rpm for 5 min - a defoaming mode of 2000 rpm for 5 min - a mixing mode of 500 rpm for 5 min.

[0017] The beneficial effects of the present invention are as follows: (1) The modified furan resin solution of the present technology has a high char yield and small shrinkage, can withstand a relatively fast heating and cooling rate during the heat treatment process without cracking easily, achieving the purpose of energy saving.

[0018] (2) The glassy carbon coating prepared by the present technology has strong adhesion and is not easy to fall off.

[0019] (3) The thickness of the glassy carbon prepared by the present technology is uniform, and the thickness of the glassy carbon on the surface of the graphite part can be adjusted arbitrarily according to the spraying amount.

[0020] (4) The layer-by-layer stacked glassy carbon coating precursor prepared by atomization spraying has better orientation, lower internal stress, and lower porosity compared to the one-time formed glassy carbon coating precursor prepared by impregnation.

[0021] (5) The glassy carbon prepared by the present technology can obtain good electrical conductivity at a relatively low heat treatment temperature. Specific Embodiments

[0022] The following examples are used to further illustrate the present invention. Their purpose is to illustrate the present invention and should not be construed as limiting the scope of the present invention. Unless otherwise specified below, all are in parts by weight and weight percentages.

[0023] The raw materials used in the present invention are all conventional commercially available products unless otherwise specified; the methods used in the present invention are all conventional methods in the art unless otherwise specified.

[0024] The planetary centrifugal mixer used in the present invention is THINKY AR-100.

[0025] The test standard for the adhesion force described in the present invention is GB / T 9286-2021.

[0026] The embodiments of the present invention will be further described below in multiple embodiments.

[0027] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application.

[0028] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms of "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0029] Example 1 (1) Mix furan resin, bismaleimide, graphene oxide dispersion, and boric acid in a volume ratio of 79:15:1:5 to form a modified furan resin solution; (2) Debubble the modified furan resin solution. Put the solution into a planetary centrifugal mixer for mixing and debubbling. The mixing and debubbling procedure: mixing mode at 1000 rpm for 5 min - defoaming mode at 2000 rpm for 5 min - mixing mode at 500 rpm for 5 min; (3) Rinse the graphite plate with ethanol in a pointed bottle. After rinsing, bake it under a baking lamp for 5 min to dry. Put the graphite part into a pressure tank and pour in a 5 wt% aqueous solution of polyimide with a molecular weight of 10,000; (4) Vacuum the pressure tank according to the procedure shown in the following table to obtain graphite part 1; Vacuum degree (mpa) Time (min) 1 -3 10 2 3 10 3 -6 10 4 6 10 5 -10 10 6 10 10 (5) Spin the graphite part 1 on a spin coater at 1000 r / min for 5 min to obtain graphite part 2; (6) Adjust the rotation speed to 4000 r / min. Take 5 ml of the debubbled modified furan resin solution and pour it into a spray gun, and atomize and spray it onto graphite part 2 to obtain graphite part 3; During the spraying process, adjust the temperature of the hot air gun to 100 °C to dry the S2 solution on the surface of the graphite part; (7) Heat-treat the graphite piece 3; the heat treatment is from room temperature to 500 °C (heating rate 5 °C / min, holding at 500 °C for 1 h), heating rate 10 °C / min to 800 °C, holding at 800 °C for 1 h, 800 °C - room temperature (cooling rate 2 °C / min); (8) Obtain a graphite piece with a high-adhesion, high-conductivity, and low-shrinkage glassy carbon coating.

[0030] Table 1 Relationship between impregnation times and porosity of graphite pieces Impregnation times 0 1 2 3 Porosity of graphite parts 5.72% 2.11% 1.03% 0.16% Example 2 (1) Mix furan resin, bismaleimide, graphene oxide dispersion, and boric acid in a volume ratio of 79:15:1:5 to form a modified furan resin solution; (2) Degas the modified furan resin solution. Put the solution into a planetary centrifugal mixer for mixing and degassing. The mixing and degassing procedure: mixing mode at 1000 rpm for 5 min - defoaming mode at 2000 rpm for 5 min - mixing mode at 500 rpm for 5 min; (3) Rinse the graphite plate with ethanol using a pipette with a pointed tip. After rinsing, bake it under a baking lamp for 3 min to dry. Put the graphite piece into a pressure tank and pour in a 10 wt% aqueous solution of polyimide with a molecular weight of 5000; (4) Evacuate the pressure tank according to the procedure shown in the following table to obtain graphite piece 1; Vacuum degree (mpa) Time (min) 1 -3 10 2 3 10 3 -6 10 4 6 10 5 -10 10 6 10 10 (5) Place graphite piece 1 on a spin coater at 1000 r / min for 5 min to obtain graphite piece 2; (6) Adjust the rotation speed to 4000 r / min. Take 5 ml of the degassed modified furan resin solution and pour it into a spray gun, and atomize and spray it onto graphite piece 2 to obtain graphite piece 3; during the spraying process, adjust the temperature of the hot air gun to 100 °C to dry the S2 solution on the surface of the graphite piece; (7) Heat-treat the graphite piece 3; the heat treatment is from room temperature to 500 °C (heating rate 5 °C / min, holding at 500 °C for 1 h), heating to 600 °C (heating rate 10 °C / min, holding at 600 °C for 1 h), 800 °C - room temperature (cooling rate 2 °C / min); (8) Obtain a graphite piece with a high-adhesion, high-conductivity, and low-shrinkage glassy carbon coating.

[0031] Example 3 (1) Mix furan resin, bismaleimide, graphene oxide dispersion, and boric acid in a volume ratio of 79:15:1:5 to form a modified furan resin solution; (2) Defoam the modified furan resin solution. Put the solution into a planetary centrifugal mixer for mixing and defoaming. The mixing and defoaming procedure: mixing mode at 1000 rpm for 5 min - defoaming mode at 2000 rpm for 5 min - mixing mode at 500 rpm for 5 min; (3) Rinse the graphite plate with ethanol in a pipette with a pointed tip. After rinsing, bake it dry under a baking lamp for 3 min. Put the graphite part into a pressure tank and pour in a 10 wt% aqueous solution of polyimide with a molecular weight of 5000; (4) Evacuate the pressure tank according to the procedure shown in the following table to obtain graphite part 1; Vacuum degree (mpa) Time (min) 1 -3 10 2 3 10 3 -6 10 4 6 10 5 -10 10 6 10 10 (5) Spin the graphite part 1 on a spin coater at 1000 r / min for 5 min to obtain graphite part 2; (6) Adjust the rotation speed to 4000 r / min. Take 2 ml of the defoamed modified furan resin solution and pour it into a spray gun, and atomize and spray it onto graphite part 2 to obtain graphite part 3; During the spraying process, adjust the temperature of the hot air gun to 100 °C to dry the S2 solution on the surface of the graphite part; (7) Heat-treat the graphite part 3; The heat treatment is from room temperature to 500 °C (heating rate 5 °C / min, holding at 500 °C for 1 h), heating to 600 °C (heating rate 10 °C / min, holding at 600 °C for 1 h), 800 °C - room temperature (cooling rate 2 °C / min); (8) Obtain a graphite part with a 5-μm-thick high-adhesion, high-conductivity, low-shrinkage glassy carbon coating.

[0032] Example 4 (1) Mix furan resin, bismaleimide, graphene oxide dispersion, and boric acid in a volume ratio of 79:15:1:5 to form a modified furan resin solution; (2) Defoam the modified furan resin solution. Put the solution into a planetary centrifugal mixer for mixing and defoaming. The mixing and defoaming procedure: mixing mode at 1000 rpm for 5 min - defoaming mode at 2000 rpm for 5 min - mixing mode at 500 rpm for 5 min; (3) Rinse the graphite plate with ethanol in a pipette with a pointed tip. After rinsing, bake it dry under a baking lamp for 3 min. Put the graphite part into a pressure tank and pour in a 10 wt% aqueous solution of polyimide with a molecular weight of 10000; (4) Evacuate the pressure tank according to the procedure shown in the following table to obtain graphite part 1; Vacuum degree (mpa) Time (min) 1 -3 10 2 3 10 3 -6 10 4 6 10 5 -10 10 6 10 10 (5) Spin the graphite part 1 on a spin coater at 1000 r / min for 5 min to obtain graphite part 2; (6) Adjust the rotational speed to 4000 r / min, take 4 ml of the defoamed modified furan resin solution and pour it into the spray gun, and atomize and spray it onto the graphite part 2 to obtain the graphite part 3; during the spraying process, adjust the temperature of the hot air gun to 100 °C to dry the S2 solution on the surface of the graphite part. (7) Heat-treat the graphite part 3; the heat treatment is from room temperature to 500 °C (heating rate 5 °C / min, holding at 500 °C for 1 h), heating to 600 °C (heating rate 10 °C / min, holding at 600 °C for 1 h), 800 °C - room temperature (cooling rate 2 °C / min). (8) Obtain a graphite part with a high-adhesion, high-conductivity, and low-shrinkage glassy carbon coating with a thickness of 10 μm.

[0033] Comparative Example 1: (1) Put the furan resin into a planetary centrifugal mixer for mixing and defoaming. The mixing and defoaming procedure: mixing mode at 1000 rpm for 5 min - defoaming mode at 2000 rpm for 10 min - mixing mode at 500 rpm for 5 min). (2) Rinse the graphite part with ethanol in a pointed bottle, and after rinsing, put it under a baking lamp for drying for 5 min. (3) Take out the graphite part and immerse it in the furan resin solution for 3 min (under standard atmospheric pressure). (4) Put the impregnated graphite part into an oven to cure the furan resin solution on the surface of the graphite part at 130 °C for 3 h. (5) Put the cured graphite part into a tube furnace for heat treatment. The heat treatment procedure: room temperature - 500 °C (heating rate 5 °C / min, holding at 500 °C for 1 h), 600 °C - 800 °C (heating rate 10 °C / min, holding at 700 °C for 1 h), 800 °C - room temperature (cooling rate 2 °C / min) (6) Take out the graphite part, and a glassy carbon coating is obtained on the surface of the graphite part. Table 2 Comparison of Coating Effects between Example 1 and Comparative Example 1 Example 1 Comparative example 1 Appearance of coating The coating is smooth and complete The coating shrinks and cracks Adhesion 5B 3B Residual carbon rate 69.4% 56.3% Shrinkage rate 12.14% 31.77% The above embodiments have detailed the structure, characteristics, and function effects of the present invention. The above are only the preferred embodiments of the present invention. Any changes made according to the concept of the present invention, or modified into equivalent embodiments with equivalent changes, still within the scope covered by the specification, should be within the protection scope of the present invention.

Claims

1. A method for preparing a glassy carbon coating with high adhesion, high conductivity and low shrinkage, characterized in that: The following steps are involved: (1) mixing furan resin, bismaleimide, 1 wt% of graphite oxide dispersion, and boric acid in a mass ratio of 79:15:1:5 to form a modified furan resin solution; (2) degassing the modified furan resin solution; (3) Place the graphite part in a pressure tank and pour in 5wt%-10wt% of a polyimide aqueous solution with a molecular weight of 5000-10000; (4) To control the pressure of the pressure tank, follow the following procedure: (4.1) -3 MPa for 10 min; (4.2) +3 MPa for 10 min; (4.3) -6 MPa for 10 min; (4.4) +6 MPa for 10 min; (4.5) -10 MPa for 10 min; (4.6) +10 MPa for 10 min to obtain graphite part 1; (5) uniformly coating the surface of graphite piece 1 with polyimide to obtain graphite piece 2; (6) Pour the degassed modified furan resin solution into an atomizing spray gun and evenly spray it onto the graphite part 2 to obtain a graphite part 3; (7) The graphite part 3 is heat treated to obtain a graphite part with a glassy carbon coating having high adhesion, high conductivity and low shrinkage.

2. The method according to claim 1, characterized in that: Before placing the graphite parts in step 3 into the pressure tank, rinse the surface with ethanol until there are no powder particles, and bake dry under a baking lamp.

3. The method according to claim 2, characterized in that The baking time is 3-5 minutes.

4. The method according to claim 1, characterized in that The uniform method in step 5 is to rotate on a glue spreader at a rotation speed of 1000 r / min for 5 minutes.

5. The method according to claim 1, characterized in that During the spraying process described in step 6, the graphite piece 2 is placed on a coating machine and rotated at 4000 r / min.

6. The method according to claim 1, characterized in that The heat treatment in step 7 is to heat from room temperature to 500°C at a rate of 5°C / min, keep it at that temperature for 1 hour, then heat up at a rate of 10°C / min to 600°C-800°C, keep it at that temperature for 1 hour, and cool down to room temperature at a rate of 2°C / min.