Carbon ceramic brake disc and method for manufacturing the same

Abstract

The application discloses a carbon ceramic brake disc and a preparation method thereof, relates to the technical field of brake discs, and comprises a disc body and a plurality of air duct groups arranged in the disc body, a connecting hole is arranged on the central axis of the disc body, a first hole group is arranged on the outer circumferential wall of the disc body, and a second hole is arranged on the inner circumferential wall of the disc body; the air duct group comprises a main air duct and at least one auxiliary air duct; the first hole group comprises a main hole and at least one auxiliary hole; one end of the main air duct is in communication with the main hole, the other end of the main air duct is in communication with the second hole; one end of the auxiliary air duct is in communication with the auxiliary hole, and the other end of the auxiliary air duct is in communication with the main air duct; the main air duct corresponds to the main hole and the second hole in a one-to-one manner; and the auxiliary air duct corresponds to the auxiliary hole in a one-to-one manner. The increase of the air ducts increases the ventilation area of the brake disc, obviously improves the heat dissipation effect, makes the carbon ceramic brake disc have superior heat resistance, prolongs the service life, obviously reduces the weight of the brake disc, and saves the manufacturing cost of the brake disc.

Description

Technical Field

[0001] This invention relates to the field of brake disc technology, specifically to carbon ceramic brake discs and their preparation methods. Background Technology

[0002] Heavy-duty semi-trailers are commercial vehicles operating in harsh environments with long periods of continuous travel, especially in the Yunnan, Guizhou, and Sichuan regions where road conditions are complex, with numerous continuous curves and inclines. During emergency braking, the brake discs endure excessive stress. Currently, most heavy-duty semi-trailer brake discs are made of cast steel. Cast iron brake discs easily generate temperatures exceeding 1000 degrees Celsius during braking, and the heat is difficult to dissipate quickly, making them highly susceptible to deformation and even cracking. Summary of the Invention

[0003] 1. The technical problem that the invention aims to solve

[0004] To address the aforementioned technical problems, this invention provides a carbon-ceramic brake disc and its preparation method, which endows the carbon-ceramic brake disc with superior heat resistance and extends its service life.

[0005] 2. Technical Solution

[0006] To solve the above problems, the technical solution provided by the present invention is as follows: a carbon ceramic brake disc, comprising a disc body and a plurality of air duct groups disposed inside the disc body, wherein a connecting hole is provided on the central axis of the disc body, a first through hole group is provided on the outer peripheral wall of the disc body, and a second through hole is provided on the inner peripheral wall of the disc body, the air duct group comprising a main air duct and at least one auxiliary air duct, the first through hole group comprising a main through hole and at least one auxiliary through hole, one end of the main air duct communicating with the main through hole and the other end of the main air duct communicating with the second through hole, one end of the auxiliary air duct communicating with the auxiliary through hole and the other end of the auxiliary air duct communicating with the main air duct, the main air duct corresponding one-to-one with the main through hole and the second through hole, and the auxiliary air duct corresponding one-to-one with the auxiliary through hole.

[0007] Optionally, the main air duct has a first included angle with the diameter of the disk body, and the secondary air duct has a second included angle with the main air duct; the first included angle ranges from 3 to 6°, and the second included angle ranges from 40 to 50°.

[0008] Optionally, the inner peripheral wall of the disc is provided with multiple teeth along the circumferential direction, and a tooth groove is formed between adjacent teeth. Each tooth includes a tooth tip and a first tooth surface and a second tooth surface located on both sides of the tooth tip. The tooth tip includes a first tooth segment, a second tooth segment, and a third tooth segment connected in sequence. The first tooth segment is connected to the first tooth surface, and the third tooth segment is connected to the second tooth surface. The first tooth segment, the second tooth segment, and the third tooth segment are all arc-shaped, and the radius of curvature of the second tooth segment is different from the radius of curvature of the first tooth segment and the radius of curvature of the third tooth segment.

[0009] Optionally, the radius of curvature of the first tooth segment and the radius of curvature of the third tooth segment are both 3 to 6 mm, and the radius of curvature of the second tooth segment is 100 to 110 mm.

[0010] Optionally, the first tooth segment and the third tooth segment are symmetrically arranged on both sides of the second tooth segment, and the radius of curvature of the first tooth segment and the radius of curvature of the third tooth segment are the same.

[0011] Optionally, the gear teeth are provided with mounting grooves at both ends along the axial direction, and the mounting grooves are used to assemble the disc hub.

[0012] Optionally, the number of teeth is odd.

[0013] Optionally, the second through hole is located at the tooth groove.

[0014] This invention also discloses a method for preparing the carbon-ceramic brake disc described above, comprising the following steps:

[0015] (1) Select non-woven fabric and carbon fiber mesh laminate, and use barbed needles to needle the non-woven fabric / carbon fiber mesh laminate so that the carbon fiber in the mesh layer is vertically inserted into the adjacent non-woven fabric layer, thereby producing a 2.5D carbon fiber preform.

[0016] (2) The carbon fiber preform obtained in step (1) is placed in a deposition furnace, and carbon source precursor and nitrogen gas that have been uniformly mixed in a mixing tank are introduced. The carbon source precursor is decomposed under vacuum at 1100-1150℃, and the generated carbon is continuously deposited on the carbon fiber preform, causing the carbon fiber preform to continuously increase in density. After 300-320 hours of deposition, the density increases to 1.4-1.6 g / cm³. 3 carbon / carbon preform is obtained;

[0017] (3) The carbon / carbon blank obtained in step (2) is placed in a high-temperature graphitization furnace and heat-treated at 1900-1950℃ for 1-3 hours to increase the porosity of the carbon / carbon blank. Then, the temperature is raised to 2400℃-2450℃ and heat-treated at high temperature for 1-3 hours to increase the graphitization degree of the carbon / carbon blank to enhance the friction performance of the brake disc.

[0018] (4) Machining the carbon / carbon blank processed in step (3) to produce air duct assembly, connecting hole, first through hole assembly, second through hole and gear teeth, to obtain the initial body of carbon ceramic brake disc;

[0019] (5) Place the carbon ceramic brake disc blank into a silicon infiltration crucible and add silicon powder, silicon carbide powder, carbon powder and alumina powder, wherein the mass ratio of silicon powder is 55-75%, the mass ratio of silicon carbide powder is 10-30%, the mass ratio of carbon powder is 5-15%, and the mass ratio of alumina powder is 2-8%. Heat treat at 1500℃-1550℃ for 3-8 hours to obtain the carbon ceramic brake disc.

[0020] Optionally, the carbon source precursor in step (2) is a mixture of methane and propylene, wherein the mass ratio of methane is 50-70%, the mass ratio of propylene is 10-30%, and the mass ratio of nitrogen is 10-30%.

[0021] 3. Beneficial effects

[0022] Compared with the prior art, the technical solution provided by this invention has the following advantages:

[0023] (1) The carbon-ceramic brake disc proposed in this application has an increased ventilation area due to the increased number of air ducts, which significantly improves the heat dissipation effect, giving the carbon-ceramic brake disc superior heat resistance and extending its service life. It also significantly reduces the weight of the brake disc, saving on manufacturing costs. In other embodiments, the number of secondary air ducts can be two or three. The main air duct and secondary air ducts form an eccentric Y-shaped structure, with the other end of the secondary air duct connected to the main air duct. The secondary air duct is not connected to or penetrates the second through hole, avoiding the second through hole having an excessively large diameter that would affect the stability of the disc.

[0024] (2) The carbon ceramic brake disc proposed in this application has an eccentric angle between the main air duct and the diameter, so that any straight line drawn from the center of the disc body must pass through the solid structure (i.e. the structure on the disc body excluding the main air duct and the secondary air duct), and the diameter of the disc body will not appear in the hollow air duct. While ensuring the heat dissipation effect of the brake disc, it can also ensure that the disc body has sufficient support strength.

[0025] (3) The carbon ceramic brake disc proposed in this application not only extends the service life of the brake disc due to its lighter weight, good hardness, stability under high pressure and high temperature conditions, thermal shock resistance and shear fracture characteristics of the same toughness, but also avoids all problems caused by load. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the carbon ceramic brake disc proposed in an embodiment of the present invention.

[0027] Figure 2 This is a cross-sectional view of the carbon ceramic brake disc proposed in an embodiment of the present invention.

[0028] Figure 3 for Figure 1 A magnified view of A in the middle.

[0029] The labels in the attached figures are as follows: 1. Disc body; 11. First through hole group; 111. Main through hole; 112. Secondary through hole; 12. Secondary through hole; 13. Connecting hole; 14. Gear tooth; 141. First tooth surface; 142. Second tooth surface; 143. Tooth tip; 1431. First tooth segment; 1432. Secondary tooth segment; 1433. Third tooth segment; 144. Mounting groove; 15. Tooth groove; 2. Air duct group; 21. Main air duct; 22. Secondary air duct; Detailed Implementation

[0030] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings and embodiments.

[0031] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. The terms "first," "second," etc., used in this invention are for the convenience of describing the technical solutions of the invention and have no specific limiting effect; they are all general terms and do not constitute a limitation on the technical solutions of the invention. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other. In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, not to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Multiple technical solutions in the same embodiment, as well as multiple technical solutions in different embodiments, can be arranged and combined to form new technical solutions that do not contradict or conflict, all of which are within the scope of protection claimed by this invention.

[0032] Example 1

[0033] Combined with appendix Figure 1-3The carbon ceramic brake disc of this embodiment includes a disc body 1 and a plurality of air duct groups 2 disposed inside the disc body 1. A connecting hole 13 is provided on the central axis of the disc body 1. A first through hole group 11 is provided on the outer peripheral wall of the disc body 1, and a second through hole 12 is provided on the inner peripheral wall of the disc body 1. The air duct group 2 includes a main air duct 21 and at least one auxiliary air duct 22. The first through hole group 11 includes a main through hole 111 and at least one auxiliary through hole 112. One end of the main air duct 21 is connected to the main through hole 111, and the other end of the main air duct 21 is connected to the second through hole 12. One end of the auxiliary air duct 22 is connected to the auxiliary through hole 112, and the other end of the auxiliary air duct 22 is connected to the main air duct 21. The main air duct 21 corresponds one-to-one with the main through hole 111 and the second through hole 12, and the auxiliary air duct 22 corresponds one-to-one with the auxiliary through hole 112. In this embodiment, the air duct group 2 includes a main air duct 21 and a secondary air duct 22. The increased number of air ducts increases the ventilation area of ​​the brake disc, significantly improving heat dissipation and giving the carbon-ceramic brake disc superior heat resistance, extending its service life. It also significantly reduces the weight of the brake disc, saving on manufacturing costs. In other embodiments, the number of secondary air ducts 22 can be two or three. The main air duct 21 and the secondary air duct 22 form an eccentric Y-shaped structure. The other end of the secondary air duct 22 is connected to the main air duct 21, and the secondary air duct 22 is not connected to or through the second through hole 12, avoiding an excessively large diameter of the second through hole 12 that could affect the stability of the disc body 1.

[0034] Example 2

[0035] Combined with appendix Figure 1-3 Compared with the technical solution of Embodiment 1, the carbon ceramic brake disc of this embodiment can be improved as follows: The main air duct 21 has a first included angle with the diameter of the disc body 1, and the secondary air duct 22 has a second included angle with the main air duct 21; the angle range of the first included angle is 3-6°, and the angle range of the second included angle is 40-50°. The main air duct 21 forms an eccentric angle with the diameter, ensuring that any straight line drawn from the center of the disc body 1 must pass through a solid structure (i.e., the structure on the disc body 1 excluding the main air duct 21 and the secondary air duct 22), preventing the diameter of the disc body 1 from appearing within a hollow air duct. This ensures both the heat dissipation effect of the brake disc and sufficient support strength of the disc body 1. The first included angle can be 3°, 4°, 5°, or 6°, and the second included angle can be 40°, 43°, 44°, 46°, 48°, or 50°.

[0036] Example 3

[0037] Combined with appendix Figure 1-3Compared with any one of the technical solutions in Embodiments 1-2, the carbon ceramic brake disc of this embodiment can be improved as follows: the inner peripheral wall of the disc body 1 is provided with a plurality of teeth 14 along the circumferential direction, and a tooth groove 15 is formed between adjacent teeth 14. The teeth 14 include a tooth tip 143 and a first tooth surface 141 and a second tooth surface 142 located on both sides of the tooth tip 143. The tooth tip 143 includes a first tooth segment 1431, a second tooth segment 1432 and a third tooth segment 1433 connected in sequence. The first tooth segment 1431 is connected to the first tooth surface 141, and the third tooth segment 1433 is connected to the second tooth surface 142. The first tooth segment 1431, the second tooth segment 1432 and the third tooth segment 1433 are all arc-shaped, and the radius of curvature of the second tooth segment 1432 is different from the radius of curvature of the first tooth segment 1431 and the radius of curvature of the third tooth segment 1433. The disc hub connects to the brake disc through the first through hole group 11. The gear teeth 14 allow the disc hub and brake disc to mesh, avoiding drilling holes in the brake disc and avoiding connecting the brake disc and disc hub with screws. The design of the first tooth segment 1431, the second tooth segment 1432 and the third tooth segment 1433 in the tooth tip 143 increases the contact area between the carbon ceramic brake disc and the disc hub, making the connection tighter and less likely to disengage during braking. The first tooth segment 1431 and the third tooth segment 1433 are arc-shaped, avoiding wear damage to the disc hub. The second tooth segment 1432 ensures a tight connection between the gear teeth and the disc hub.

[0038] Example 4

[0039] Combined with appendix Figure 1-3 Compared with any one of the technical solutions in embodiments 1-3, the carbon ceramic brake disc of this embodiment can be improved as follows: the radius of curvature of the first tooth segment 1431 and the radius of curvature of the third tooth segment 1433 are both 3-6 mm, and the height of the tooth tip 143 of the second tooth segment 1432 is 100-110 mm. The radius of curvature of the first tooth segment 1431 can be 3 mm, 5 mm, or 6 mm, and the radius of curvature of the third tooth segment 1433 can be 3 mm, 5 mm, or 6 mm, and the height of the radius of curvature of the third tooth segment 1433 can be 100 mm, 105 mm, 108 mm, or 110 mm. If the radius of curvature of the first and third tooth segments exceeds 6 mm, it will affect the normal meshing of the gear teeth and the disc hub.

[0040] Example 5

[0041] Combined with appendix Figure 1-3 Compared with any one of the technical solutions in embodiments 1-4, the carbon ceramic brake disc of this embodiment can be improved as follows: the first tooth segment 1431 and the third tooth segment 1433 are symmetrically arranged on both sides of the second tooth segment 1432, and the radius of curvature of the first tooth segment 1431 and the radius of curvature of the third tooth segment 1433 are the same. The symmetrical arrangement of the first tooth segment 1431 and the third tooth segment 1433 on both sides of the second tooth segment 1432 makes the tooth structure 14 more stable.

[0042] Example 6

[0043] Combined with appendix Figure 1-3 Compared with any one of the technical solutions in embodiments 1-5, the carbon ceramic brake disc of this embodiment can be improved as follows: the second through hole 12 is provided at the tooth groove 15. The second through hole 12 is provided at the tooth groove 15, which avoids the second through hole 12 being provided on the wheel tooth 14 and affecting the meshing between the wheel tooth 14 and the disc hub.

[0044] Example 7

[0045] Combined with appendix Figure 1-3 Compared with the technical solutions of Embodiment 1 or 2, the carbon ceramic brake disc of this embodiment can be improved as follows: the wheel teeth 14 are respectively provided with mounting grooves 144 at both ends along the axial direction, and the mounting grooves 144 are used to assemble the disc hub.

[0046] Example 8

[0047] Combined with appendix Figure 1-3 Compared with any of the technical solutions in embodiments 1-3, the carbon ceramic brake disc of this embodiment can be improved as follows: the number of the gear teeth 14 is odd, which avoids the occurrence of symmetrical main air ducts or secondary air ducts on a straight line with even-numbered gear teeth, forming an eccentric structure and enhancing stability.

[0048] The present invention also discloses a method for preparing the carbon ceramic brake disc according to any one of claims 1 to 8, comprising the following steps:

[0049] (1) Select non-woven fabric and carbon fiber mesh laminate, and use barbed needles to needle the non-woven fabric / carbon fiber mesh laminate so that the carbon fiber in the mesh layer is vertically inserted into the adjacent non-woven fabric layer, thereby producing a 2.5D carbon fiber preform.

[0050] (2) The carbon fiber preform obtained in step (1) is placed in a deposition furnace, and carbon source precursor and nitrogen gas that have been uniformly mixed in a mixing tank are introduced. The carbon source precursor is decomposed under vacuum at 1100℃-1150℃, and the generated carbon is continuously deposited on the carbon fiber preform, causing the carbon fiber preform to continuously increase in density. After 300-320 hours of deposition, the density increases to 1.4-1.6 g / cm³. 3 carbon / carbon preform is obtained;

[0051] (3) The carbon / carbon blank obtained in step (2) is placed in a high-temperature graphitization furnace and heat-treated at 1900-1950℃ for 1-3 hours to increase the porosity of the carbon / carbon blank. Then, the temperature is raised to 2400℃-2450℃ and heat-treated at high temperature for 1-3 hours to increase the graphitization degree of the carbon / carbon blank to enhance the friction performance of the brake disc.

[0052] (4) The carbon / carbon blank processed in step (3) is machined to produce air duct group 2, connecting hole 13, first through hole group 11, second through hole 12 and gear teeth 14, to obtain the carbon ceramic brake disc prototype.

[0053] (5) Place the initial carbon-ceramic brake disc in a silica-diffusion crucible and add silicon powder, silicon carbide powder, carbon powder, and alumina powder. The mass ratio of silicon powder is 55-75%, silicon carbide powder is 10-30%, carbon powder is 5-15%, and alumina powder is 2-8%. Heat treat at 1500℃-1550℃ for 3-8 hours to obtain the carbon-ceramic brake disc. The role of carbon fiber is to provide the required mechanical strength and fracture toughness of the material. Silicon carbide determines the hardness of the composite material. Silicon and graphite improve the friction coefficient of the brake disc. Alumina has an anti-oxidation effect in the carbon-ceramic disc. The carbon-ceramic brake disc not only extends the service life of the brake disc due to its lighter weight, good hardness, stability under high pressure and high temperature conditions, thermal shock resistance, and iso-tough shear fracture characteristics, but also avoids all problems caused by load.

[0054] In this embodiment, a non-woven fabric with a density of 260 g / m² and a mesh layer with a surface density of 50 g / m² are selected for needle punching. The needle punching density is 35 needles / cm², the needle penetration depth is 16-20 mm, the interlayer density of needle punching depth is 15 layers / 10 mm, the bulk density is 0.45-0.48 g / cm³, the carbon fiber volume fraction is 30%, and the T-type peel strength is 0.32 KN / m.

[0055] A mixture of 60% methane, 20% propylene, and 20% hydrogen is used. After thorough mixing in a mixing tank, the mixture is introduced into the furnace and subjected to pyrolysis under a high-temperature vacuum environment of 1100℃-1150℃. The resulting carbon continuously deposits onto the preform, causing it to gradually thicken. After 300-320 hours of deposition, the density reaches 1.5 g / cm³. 3 This yields a carbon / carbon preform.

[0056] A carbon-ceramic brake disc was obtained by heat-treating a mixture of 65% silicon powder, 20% silicon carbide powder, 10% carbon powder, and 5% alumina powder at 1500℃-1550℃ for 5 hours. Nitrogen was used to improve deposition efficiency and obtain carbon deposits with a uniform rough layer structure.

[0057] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A carbon-carbide brake disc characterised in that, The disc body is provided with a connecting hole on the central axis, a first through hole group on the outer peripheral wall, and a second through hole on the inner peripheral wall. The inner peripheral wall of the disc body is provided with a plurality of gear teeth in the circumferential direction, and a tooth slot is formed between adjacent gear teeth. The gear tooth includes a tooth top and first and second tooth surfaces on both sides of the tooth top. The tooth top includes a first tooth segment, a second tooth segment, and a third tooth segment connected in sequence.

2. The carbon-carbon brake disc of claim 1 wherein, The first tooth segment is connected with the first tooth surface, and the third tooth segment is connected with the second tooth surface.

3. The carbon-carbon brake disc of claim 1 wherein, The first tooth segment, the second tooth segment, and the third tooth segment are all arc-shaped, and the curvature radius of the second tooth segment is different from that of the first tooth segment and the third tooth segment.

4. The carbon-carbon brake disc of claim 1 wherein, The curvature radius of the first tooth segment and the third tooth segment is 3-6 mm, and the curvature radius of the second tooth segment is 100-110 mm.

5. The carbon-carbon brake disc of claim 1 wherein, The first tooth segment and the third tooth segment are symmetrically arranged on both sides of the second tooth segment, and the curvature radius of the first tooth segment is the same as that of the third tooth segment.

6. A method for manufacturing the carbon-carbon brake disc according to any one of claims 1 to 5, characterized in that, The first angle between the main air duct and the diameter of the disc body is 3-6°, and the second angle between the auxiliary air duct and the main air duct is 40-50°. The gear tooth is provided with a mounting groove at each of the axial ends. The number of gear teeth is odd. The second through hole is arranged at the tooth slot. The method comprises the following steps: (1) selecting a no-woven fabric and a carbon fiber web tire stack, and using a barbed needle to needle punch the no-woven fabric / carbon fiber web tire stack, so that the carbon fibers in the web tire layer are vertically pierced into the adjacent no-woven fabric layer, thereby obtaining a 2.5D carbon fiber preform; (2) placing the carbon fiber preform obtained in step (1) into a deposition furnace, and introducing a carbon source precursor and nitrogen gas mixed uniformly through a gas mixing tank, so that the carbon source precursor is cracked at 1100-1150°C under vacuum, and the generated carbon continuously deposits on the carbon fiber preform, so that the carbon fiber preform is continuously densified, and after deposition for 300-320h, the density is increased to 1.4-1.6 g / cm³, thereby obtaining a carbon / carbon blank; (3) placing the carbon / carbon blank obtained in step (2) into a high-temperature graphitization furnace, and heat treating at 1900-1950°C for 1-3h to increase the opening rate of the carbon / carbon blank, and then increasing the temperature to 2400-2450°C, and heat treating at high temperature for 1-3h to increase the graphitization degree of the carbon / carbon blank to enhance the friction performance of the brake disc; (4) mechanically processing the carbon / carbon blank treated in step (3) to process the air duct group, the connecting hole, the first through hole group, the second through hole, and the gear tooth, thereby obtaining a carbon ceramic brake disc preliminary body. (5) Put the carbon ceramic brake disc initial body into the silicon infiltration crucible, and add silicon powder, silicon carbide powder, carbon powder and alumina powder, wherein the mass ratio of the silicon powder is 55-75%, the mass ratio of the silicon carbide powder is 10-30%, the mass ratio of the carbon powder is 5-15%, and the mass ratio of the alumina powder is 2-8%, heat treat at 1500-1550°C for 3-8h to obtain the carbon ceramic brake disc.

7. The method of manufacturing a carbon-ceramic brake disc according to claim 6, characterized in that, The carbon source precursor in the step (2) is a mixed gas of methane and propylene, wherein the mass ratio of the methane is 50-70%, the mass ratio of the propylene is 10-30%, and the mass ratio of the nitrogen is 10-30%.

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