An antioxidant sealing carbon graphite material and a preparation method thereof

Abstract

The application discloses an antioxidant sealing carbon graphite material and a preparation method thereof. The preparation method comprises the following steps: (1) mixing and kneading semi-reinforcing carbon black and a binder A to obtain a first-stage material; (2) dry mixing calcined petroleum coke, calcined pitch coke, flake graphite, titanium powder and the first-stage material obtained in the step (1) to obtain dry powder; (3) adding aluminum oxide and a binder B to the dry powder in the step (2) and mixing and kneading to obtain a paste; (4) rolling, grinding, pre-molding and isostatic pressing the paste obtained in the step (3) to obtain a blank; and (5) performing one-time baking, impregnation, two-time baking and graphitization treatment on the blank in the step (4), so that the antioxidant sealing carbon graphite material is obtained. The carbon graphite material prepared by the application has high graphitization degree and good antioxidant performance.

Description

Technical Field

[0001] This invention belongs to the field of materials technology, and relates to carbon graphite materials, and particularly to an antioxidant sealing carbon graphite material and its preparation method. Background Technology

[0002] Graphite materials are made from various carbonaceous raw materials, which are mixed with binders and additives, and then processed through rolling, grinding, sieving, pressing, sintering, and graphitization. Due to its excellent corrosion resistance, high strength, thermal shock resistance, thermal and electrical conductivity, and self-lubricating properties, it has long been the preferred material for mechanical seal rings. However, with its application in aerospace and other harsh environments such as high and low temperatures (-180~650℃) and high speeds (≥20000r / min), more stringent requirements have been placed on the sealing performance, oxidation resistance, and thermal stability of graphite materials. Therefore, it is necessary to develop a sealing graphite material that is resistant to high temperatures, oxidation, and has excellent mechanical properties.

[0003] Invention patent CN 114804876 A discloses a method for preparing a high-wear-resistant end-face sealing graphite material. It uses ultrafine coke powder (particle size below 10μm), iron oxide red powder, graphite powder, and N330 carbon black as raw materials. The process involves a two-stage production process of ball milling and secondary kneading, followed by isostatic pressing and impregnation with antimony alloy to prepare the sealing graphite material. This invention improves the internal uniformity of the product, enhances its performance, and improves its sealing properties and high-temperature wear resistance. Invention patent CN109133926 A discloses a sealing graphite material and its preparation method. It uses graphene oxide powder, carbon black, special graphite powder, and medium-temperature pitch as raw materials. The process involves mixing, pressing, carbonizing, purifying, impregnating, and curing to obtain a graphite material with a uniform and delicate structure, high bulk density, and excellent physicochemical properties. The isostatically pressed graphite material has a blank density of 1.76~1.80 g / cm³. 3 These technologies possess characteristics such as high load capacity, low wear, high temperature resistance, high thermal conductivity, and corrosion resistance. However, they have not significantly improved the material's poor oxidation resistance. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the existing technology, the purpose of this invention is to provide an antioxidant sealing carbon graphite material and its preparation method. The carbon graphite material prepared by this invention has a high degree of graphitization and good antioxidant properties.

[0005] The technical solution of this invention is implemented as follows:

[0006] A method for preparing an antioxidant sealing carbon graphite material includes the following steps:

[0007] (1) Mix the semi-reinforcing carbon black and binder A to obtain a first-stage material;

[0008] (2) The calcined petroleum coke, calcined pitch coke, flake graphite, titanium powder and the first-stage material obtained in step (1) are dry-mixed to obtain dry powder;

[0009] (3) Add alumina and binder B to the dry powder in step (2) and knead to obtain a paste;

[0010] (4) The paste obtained in step (3) is rolled, ground, pre-molded and isostatically pressed to obtain a blank;

[0011] (5) The blank in step (4) is subjected to a first firing, impregnation, a second firing and graphitization treatment in sequence to obtain the antioxidant sealing carbon graphite material.

[0012] Furthermore, both binder A and binder B are one of medium-temperature asphalt, high-temperature asphalt, or low-temperature asphalt; preferably, binder B is modified asphalt with a softening point of 90~110 ℃.

[0013] Furthermore, in step (1), the mass ratio of semi-reinforcing carbon black to binder A is 1~10:10~100.

[0014] Further, in step (2), the mass ratio of calcined petroleum coke, calcined pitch coke, first-stage material, flake graphite and titanium powder is (40~50):(30~40):(5~15):(5~10):(0~15), preferably (40~50):(30~40):(5~15):(5~10):(3~9).

[0015] Furthermore, in step (2), the dry mixing temperature is 100~120 ℃ and the dry mixing time is 0.5~1.5 h.

[0016] Furthermore, the amount of binder B added is 40-50% of the total mass of the dry powder, and the amount of alumina added is 0-5% of the total mass of the dry powder, preferably 2-3%; the binder B and alumina are mixed evenly before being added to the dry powder.

[0017] Further, in step (4), the number of rolling cycles is 2, the thickness of the rolled sheet is ≤2 mm, the particle size after grinding is 45~55μm; the pre-molding pressure is 20~30 MPa; during isostatic pressing, the vacuum degree is ≥0.09 MPa, the pressure is 130~150 MPa, and the holding time is 10~20 min.

[0018] Further, in step (5), the process of the first and second calcination is as follows: the temperature is raised from room temperature to 350 ℃, and then raised to 450 ℃ at a heating rate of 3 ℃ / h; then raised to 550 ℃ at a heating rate of 2.5 ℃ / h; then raised to 700 ℃ at a heating rate of 1.5 ℃ / h; then raised to 850 ℃ at a heating rate of 2 ℃ / h; then raised to 900 ℃ at a heating rate of 7.5 ℃ / h; then raised to 1000~1200 ℃ at a heating rate of 10 ℃ / h, and the temperature is maintained for 5~20 h after the heating in each temperature range is completed.

[0019] Furthermore, in step (5), during impregnation, the asphalt is impregnated at 180~200 ℃ for 4~6 h; the graphitization temperature is 2400~2600 ℃, and the temperature is maintained for 1~5 h.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. In this invention, alumina is mixed into a binder and then kneaded with aggregates such as calcined petroleum coke and calcined pitch coke. During the kneading process, alumina is evenly distributed between the aggregate particles. Alumina has good high-temperature stability and generates carbides with high-temperature binding properties during the graphitization process, thereby playing a protective role between the aggregate particles and improving the oxidation resistance of carbon graphite materials.

[0022] 2. In this invention, titanium powder is doped into the aggregate. Titanium powder can catalyze graphitization. During heat treatment under a protective atmosphere, carbon and titanium powder react to form carbides. As the graphitization temperature increases, disordered carbon will continuously interact with these carbides to form more complete graphite crystals, thereby increasing the degree of graphitization and thus improving the oxidation resistance of carbon-graphite materials.

[0023] 3. In this invention, calcined petroleum coke and calcined pitch coke are used as the main aggregate phases. Calcined petroleum coke and calcined pitch coke contain low volatile matter, effectively reducing impurities in the carbon-graphite material and facilitating graphitization. Therefore, graphitization treatment effectively improves the graphitization degree of the carbon-graphite material. Semi-reinforcing carbon black is first mixed with a binder and then used as an aggregate, which helps improve the hardness of the carbon-graphite material. Flake graphite effectively improves the thermal stability of the carbon-graphite material. It was also found that the addition of titanium powder and alumina effectively improves the flexural and compressive strength of the carbon-graphite material, enhancing its mechanical properties. Attached Figure Description

[0024] Figure 1 - Process flow diagram of the present invention. Detailed Implementation

[0025] A method for preparing an antioxidant sealing carbon graphite material, the process flow diagram of which is shown below. Figure 1 As shown, it includes the following steps:

[0026] (1) Mix semi-reinforcing carbon black and binder A to obtain a first-stage material; the mass ratio of semi-reinforcing carbon black to binder A is 1~10:10~100;

[0027] (2) Add calcined petroleum coke, calcined pitch coke, flake graphite, titanium powder and the first-stage material obtained in step (1) into a kneader, heat to 100~120 ℃, dry mix for 0.5~1.5 h to obtain dry powder; wherein, the mass ratio of calcined petroleum coke, calcined pitch coke, first-stage material, flake graphite and titanium powder is (40~50):(30~40):(5~15):(5~10):(0~15);

[0028] (3) After mixing alumina and binder B, the molten binder B is added to the dry powder in step (2), and kneaded for 1-2 hours to obtain a paste; wherein the amount of alumina added is 0-5% of the total mass of the dry powder, and the amount of binder B added is 40-50% of the total mass of the dry powder;

[0029] (4) Roll the paste obtained in step (3) twice, with a sheet thickness ≤ 2 mm, and then cool it to room temperature before grinding to obtain pressed powder with a particle size of about 45~55 μm; pre-press the pressed powder at 20~30 MPa, and then isostatically press it (vacuum degree ≥ 0.09 MPa, pressure of 130~150 MPa for 10~20 min) to obtain a blank;

[0030] (5) The blank from step (4) is calcined at 1000~1200 ℃, then impregnated at 180~200 ℃ for 4~6 h, calcined again, and finally graphitized at 2400~2600 ℃ to obtain the antioxidant sealing carbon graphite material.

[0031] In specific implementation, in step (5), the two roasting processes are as follows: from room temperature to 350 ℃, and then hold for 5~20 h; then raise the temperature to 450 ℃ at a rate of 3 ℃ / h, and then hold for 5~20 h; then raise the temperature to 550 ℃ at a rate of 2.5 ℃ / h, and then hold for 5~20 h; then raise the temperature to 700 ℃ at a rate of 1.5 ℃ / h, and then hold for 5~20 h; then raise the temperature to 850 ℃ at a rate of 2 ℃ / h, and then hold for 5~20 h; then raise the temperature to 900 ℃ at a rate of 7.5 ℃ / h, and then hold for 5~20 h; then raise the temperature to 1000~1200 ℃ at a rate of 10 ℃ / h, and then hold for 5~20 h.

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0033] In the following embodiments, the calcination process is as follows: heating from room temperature to 350 °C and holding for 5 h; then heating to 450 °C at a heating rate of 3 °C / h and holding for 15 h; then heating to 550 °C at a heating rate of 2.5 °C / h and holding for 20 h; then heating to 700 °C at a heating rate of 1.5 °C / h and holding for 15 h; then heating to 850 °C at a heating rate of 2 °C / h and holding for 10 h; then heating to 900 °C at a heating rate of 7.5 °C / h and holding for 10 h; then heating to 1000~1200 °C at a heating rate of 10 °C / h and holding for 5 h.

[0034] Example 1

[0035] The preparation method of antioxidant sealing carbon graphite material is as follows:

[0036] 1) Mix 1 part of semi-reinforcing carbon black and 10 parts of medium-temperature asphalt to obtain a first-stage material;

[0037] 2) Add 42 parts of calcined petroleum coke, 40 parts of calcined pitch coke, 5 parts of flake graphite, 10 parts of first-stage material powder, and 3 parts of titanium powder to a kneader and dry mix for 0.5 h. After the temperature rises to 100 ℃, continue kneading for another 0.5 h to obtain dry powder.

[0038] 3) Add molten modified asphalt mixed with alumina to the dry powder and continue kneading for 1 hour to obtain a paste; wherein the amount of modified asphalt powder used as a binder accounts for 40% of the total mass of the dry powder, and the amount of alumina mixed in is 2% of the total mass of the dry powder;

[0039] 4) Roll the paste twice, and measure the thickness of the rolled sheet to be ≤2 mm;

[0040] 5) Grind the rolled sheets into powder to obtain compressed powder with a particle size of 45μm;

[0041] 6) The powder from 5) is first pre-molded under a pressure of 20 MPa, then isostatically pressed under a pressure of 130 MPa, and then placed under a nitrogen atmosphere and calcined according to the above calcination process to obtain the initial graphite blank.

[0042] 7) The initial graphite blank was impregnated with asphalt at 200 ℃ for 5 h, and then subjected to a second calcination process in the same manner as in 6). Then, it was graphitized at 2500 ℃ and kept at that temperature for 2 h to obtain an antioxidant sealing carbon graphite material.

[0043] Example 2

[0044] The preparation method of the antioxidant sealing carbon graphite sealing material is as follows:

[0045] 1) Mix 1 part of semi-reinforcing carbon black and 10 parts of medium-temperature asphalt to obtain a first-stage material;

[0046] 2) Add 40 parts of calcined petroleum coke, 39 parts of calcined pitch coke, 5 parts of flake graphite, 10 parts of first-stage material powder, and 6 parts of titanium powder to a kneader and dry mix for 0.5 h. After the temperature rises to 100 ℃, continue kneading for another 0.5 h to obtain dry powder.

[0047] 3) Add molten modified asphalt mixed with alumina to the dry powder and continue kneading for 1 hour to obtain a paste; wherein the amount of modified asphalt powder used as binder accounts for 45% of the total mass of the dry powder, and the amount of alumina mixed in is 3% of the total mass of the dry powder;

[0048] 4) Roll the paste twice, and measure the thickness of the rolled sheet to be ≤2mm;

[0049] 5) Grind the rolled sheets into powder to obtain compressed powder with a particle size of 45μm;

[0050] 6) The powder from 5) is first pre-molded under a pressure of 20 MPa, then isostatically pressed under a pressure of 130 MPa, and then placed under a nitrogen atmosphere and calcined according to the above calcination process to obtain the initial graphite blank.

[0051] 7) The initial graphite blank was impregnated with asphalt at 200 ℃ for 5 h, and then subjected to a second calcination process in the same manner as in 6). Then, it was graphitized at 2500 ℃ and kept at that temperature for 2 h to obtain an antioxidant sealing carbon graphite material.

[0052] Example 3

[0053] The preparation method of the antioxidant sealing carbon graphite sealing material is as follows:

[0054] 1) Mix 1 part of semi-reinforcing carbon black and 10 parts of medium-temperature asphalt to obtain a first-stage material;

[0055] 2) Add 40 parts of calcined petroleum coke, 36 parts of calcined pitch coke, 5 parts of flake graphite, 10 parts of first-stage material powder, and 9 parts of titanium powder to a kneader and dry mix for 1 hour. After the temperature rises to 110 ℃, continue kneading for 0.5 hours to obtain dry powder.

[0056] 3) Add molten modified asphalt mixed with alumina to the dry powder and continue kneading for 1 hour to obtain a paste; wherein the amount of modified asphalt powder used as binder accounts for 47% of the total mass of the dry powder, and the amount of alumina mixed in is 3% of the total mass of the dry powder;

[0057] 4) Roll the paste twice, and measure the thickness of the rolled sheet to be ≤2 mm;

[0058] 5) Grind the rolled sheets into powder to obtain compressed powder with a particle size of 45 μm;

[0059] 6) The powder from 5) is first pre-molded under a pressure of 25 MPa, then isostatically pressed under a pressure of 140 MPa, and then placed in a nitrogen atmosphere and calcined according to the above calcination process to obtain the initial graphite blank.

[0060] 7) The initial graphite blank was impregnated with asphalt at 180 ℃ for 6 h, and then subjected to a second calcination process in the same manner as in 6). Then, it was graphitized at 2500 ℃ and kept at that temperature for 2 h to obtain an antioxidant sealing carbon graphite material.

[0061] Example 4

[0062] The preparation method of the antioxidant sealing carbon-graphite sealing material in this embodiment is as follows:

[0063] 1) Mix 1 part of semi-reinforcing carbon black and 10 parts of medium-temperature asphalt to obtain a first-stage material;

[0064] 2) Add 40 parts of calcined petroleum coke, 33 parts of calcined pitch coke, 5 parts of flake graphite, 10 parts of first-stage material powder, and 12 parts of titanium powder to a kneader and dry mix for 1 hour. After the temperature rises to 120 ℃, continue kneading for 0.5 hours to obtain dry powder.

[0065] 3) Add molten modified asphalt mixed with alumina to the dry powder and continue kneading for 1 hour to obtain a paste; wherein the amount of modified asphalt powder used as binder accounts for 50% of the total mass of the dry powder, and the amount of alumina mixed in is 5% of the total mass of the dry powder;

[0066] 4) Roll the paste twice, and measure the thickness of the rolled sheet to be ≤2 mm;

[0067] 5) Grind the rolled sheets into powder to obtain compressed powder with a particle size of 45μm;

[0068] 6) The powder from 5) is first pre-molded under a pressure of 30 MPa, then isostatically pressed under a pressure of 150 MPa, and then placed in a nitrogen atmosphere and calcined according to the heating curve in the specific implementation method to obtain the initial graphite blank.

[0069] 7) The initial graphite blank was impregnated with asphalt at 200 ℃ for 6 h, and then subjected to a second calcination process in the same manner as in 6). Then, it was graphitized at 2500 ℃ and kept at that temperature for 2 h to obtain an antioxidant sealing carbon graphite material.

[0070] Comparative Example 1

[0071] This embodiment is the same as Embodiment 2, except that aluminum oxide is not added in this embodiment.

[0072] Comparative Example 2

[0073] This embodiment is the same as Embodiment 2, except that no titanium powder is added in this embodiment.

[0074] Comparative Example 3

[0075] This embodiment is the same as Embodiment 2, except that titanium powder and aluminum oxide are not added in this embodiment.

[0076] The performance of the antioxidant sealing carbon graphite materials obtained in Examples 1-4 and Comparative Examples 1-3 was tested, and the test data are shown in the table below.

[0077] Performance parameters of the antioxidant sealing carbon graphite materials obtained in Examples 1-4 and Comparative Examples 1-3

[0078]

[0079] As can be seen from the table above: (1) Compared with Comparative Example 3, Comparative Example 1 added titanium powder, and Comparative Example 2 added alumina, both of which can effectively improve the graphitization degree of carbon graphite materials, thereby improving the oxidation resistance of carbon graphite materials. Example 2 added both titanium powder and alumina, and the carbon graphite material had a higher graphitization degree and stronger oxidation resistance, indicating that there is a synergistic effect between the addition of titanium powder and alumina to improve the graphitization degree of carbon graphite materials and improve their oxidation resistance.

[0080] (2) In Examples 1 to 4, titanium powder and alumina were added simultaneously, which is beneficial to improve the graphitization degree and antioxidant properties of carbon graphite materials. However, it was also found that as the amount of titanium powder and alumina added increased, the graphitization degree and antioxidant properties first increased and then decreased. When the amount of titanium powder added was 3 to 9 parts, that is, when the mass ratio of calcined petroleum coke, calcined pitch coke, first-stage material, flake graphite and titanium powder was (40 to 50): (30 to 40): (5 to 15): (5 to 10): (3 to 9), and the alumina was 2 to 3% of the total mass of dry powder, the carbon graphite materials had excellent antioxidant properties.

[0081] (3) Compared with Comparative Example 3, Examples 1 to 4 and Comparative Examples 1 to 2 added titanium powder and / or alumina. The carbon graphite materials of Examples 1 to 4 and Comparative Examples 1 to 2 have excellent bulk density, flexural strength, compressive strength and hardness, indicating that the addition of titanium powder and alumina can improve the oxidation resistance of carbon graphite materials and also enhance the mechanical properties of carbon graphite materials.

[0082] Finally, it should be noted that the above embodiments of the present invention are merely illustrative examples and not intended to limit the implementation of the invention. Those skilled in the art can make other variations and modifications based on the above description. It is impossible to exhaustively list all possible implementations here. All obvious variations or modifications derived from the technical solutions of this invention are still within the scope of protection of this invention.

Claims

1. A method for producing an antioxidant-sealed carbon graphite material, characterized by, The method comprises the following steps: (1) knead semi-reinforcing carbon black and binder A to obtain a first-stage material; the binder A is one of medium-temperature pitch, high-temperature pitch or low-temperature pitch, and the mass ratio of semi-reinforcing carbon black to binder A is 1-10:10-100; (2) dry-mix calcined petroleum coke, calcined pitch coke, flake graphite, titanium powder and the first-stage material obtained in step (1) to obtain dry powder; the mass ratio of calcined petroleum coke, calcined pitch coke, the first-stage material, flake graphite and titanium powder is (40-50):(30-40):(5-15):(5-10):(0-15); (3) uniformly mix binder B and aluminum oxide, and then add the dry powder in step (2) to obtain a paste by kneading; the addition amount of aluminum oxide is 2-3% of the total mass of the dry powder; the binder B is modified pitch; the addition amount of the binder B is 40-50% of the total mass of the dry powder; (4) roll, grind, pre-mold and isostatic press the paste obtained in step (3) to obtain a blank; (5) the blank in step (4) is subjected to primary roasting, impregnation, secondary roasting and graphitization in sequence to obtain the oxidation-resistant sealing carbon graphite material.

2. The method of claim 1, wherein the antioxidant sealing carbon graphite material is prepared by the steps of: The softening point of the binder B is 90-110 ℃. ​ 3. The method of claim 1 or 2, wherein the antioxidant sealing carbon graphite material is prepared by the steps of: In step (2), the mass ratio of calcined petroleum coke, calcined pitch coke, the first-stage material, flake graphite and titanium powder is (40-50):(30-40):(5-15):(5-10):(3-9). ​ 4. The method of claim 1 or 2, wherein the antioxidant sealing carbon graphite material is prepared by the steps of: In step (2), the dry-mixing temperature is 100-120 ℃, and the dry-mixing time is 0.5-1.5 h. ​ 5. The method of claim 1, wherein the antioxidant sealing carbon graphite material is prepared by the steps of: mixing a carbon graphite material with a first antioxidant; and mixing the carbon graphite material with a second antioxidant. In step (4), the rolling frequency is 2 times, the rolled sheet thickness is ≤2 mm, and the particle size after grinding is 45-55 μm; the pre-molding pressure is 20-30 MPa; during isostatic pressing, the vacuum degree is ≥0.09 MPa, the pressure is 130-150 MPa, and the pressure maintaining time is 10-20 min.

6. The method of claim 1, wherein the antioxidant sealing carbon graphite material is prepared by the steps of: mixing a carbon graphite material with a first antioxidant; and mixing the carbon graphite material with a second antioxidant. In step (5), the process of primary roasting and secondary roasting is as follows: from room temperature to 350 ℃, free heating; then at a heating rate of 3 ℃ / h to 450 ℃; then at a heating rate of 2.5 ℃ / h to 550 ℃; then at a heating rate of 1.5 ℃ / h to 700 ℃; then at a heating rate of 2 ℃ / h to 850 ℃; then at a heating rate of 7.5 ℃ / h to 900 ℃; then at a heating rate of 10 ℃ / h to 1000-1200 ℃, and the temperature in each interval is maintained for 5-20 h after the temperature is raised.

7. The method of claim 1, wherein the antioxidant sealing carbon graphite material is prepared by the steps of: mixing a carbon graphite material with a first antioxidant; and mixing the carbon graphite material with a second antioxidant. In step (5), during impregnation, the pitch is impregnated at 180-200 ℃ for 4-6 h; the graphitization temperature is 2400-2600 ℃, and the temperature is maintained for 1-5 h.

8. An antioxidant-sealed carbon graphite material, characterized by, The oxidation-resistant sealing carbon graphite material is prepared by the method in any one of claims 1-7.

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