Carbon-ceramic brake disc with ceramic coating and preparation method of carbon-ceramic brake disc

Abstract

The invention relates to the technical field of carbon-ceramic brake discs, and particularly discloses a carbon-ceramic brake disc with a ceramic coating and a preparation method of the carbon-ceramic brake disc with the ceramic coating. On one hand, the shear strength of the carbon-ceramic brake disc base body prepared through the short fiber mold pressing technology in the direction parallel to the friction face can be improved, and meanwhile, the carbon fiber tows connect the ceramic coating on the surface with the base body, so that the binding power between the ceramic coating on the surface of the carbon-ceramic brake disc and the carbon-ceramic brake disc base body is improved, and the service life of the carbon-ceramic brake disc is prolonged. And finally, the problems that the carbon-ceramic brake disc prepared by adopting a short fiber mold pressing process at present is easy to crack after being used for a long time and the ceramic coating on the surface is easy to collapse when the carbon-ceramic brake disc with the ceramic coating is prepared are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon ceramic brake discs, in particular to a carbon ceramic brake disc with a ceramic coating and a preparation method thereof. BACKGROUND

[0002] In recent years, with the rapid development of new energy vehicles, as the carbon ceramic brake disc used for braking of vehicles, due to its light weight, high strength, excellent wear resistance and the ability to withstand high temperature braking above 1000℃, etc., compared with ordinary steel brake disc, it can reduce weight by 2 / 3, and can effectively avoid the deformation caused by overheating of the disc body during high-speed braking, etc., so that the carbon ceramic brake disc can well meet the requirements of new energy vehicles for pursuing lightweight and high performance.

[0003] At present, the carbon ceramic brake disc products mainly include two categories of short fiber molding process and long fiber needling process. Among them, for the long fiber needling process to prepare carbon ceramic brake disc, it usually needs to go through the CVI deposition densification process, on the one hand, the cycle is long, which affects the production efficiency of the product; on the other hand, the preparation cost is also relatively high, which leads to that the carbon ceramic brake disc produced by the process cannot be mass produced and applied in the entire automobile braking field, but can only be preferentially applied to some high-end vehicle models. As for the short fiber molding process to prepare carbon ceramic brake disc, due to the relatively low cost of raw materials and process required for production, and the relatively shorter production cycle, it has the possibility of mass application in the entire automobile braking field by using the low-cost short fiber molding process to produce and manufacture carbon ceramic brake disc.

[0004] However, for the short fiber molding process to prepare carbon ceramic brake disc, due to the relatively poor mechanical properties of the carbon ceramic brake disc prepared by the process compared with the mechanical properties of the carbon ceramic brake disc prepared by the long fiber needling process, especially the shear strength of the material, considering that the carbon ceramic brake disc will be subjected to a high degree of shear force during high-speed braking, after a long time of use, there is a risk that cracks will appear on the surface of the carbon ceramic brake disc or even the carbon ceramic brake disc will crack.

[0005] In addition, for the ordinary carbon ceramic brake disc, due to the existence of some exposed carbon fibers on the upper and lower friction surfaces which are not covered by deposited carbon or resin carbon, the exposed carbon fibers are prone to oxidation during high-speed braking due to brake friction heat, and some uneven 'etch pits' are formed in some areas of the friction surface. At present, it is proposed to prepare a certain thickness (usually 1mm~2mm) of ceramic coating with wear resistance and oxidation resistance on the upper and lower friction surfaces of the ordinary carbon ceramic brake disc, which can effectively solve the above problems. At the same time, the wear resistance of the ceramic coating is better than that of the carbon ceramic material, which can further improve the service life of the carbon ceramic brake disc itself. However, considering the difference in thermal expansion coefficient between the ceramic coating and the carbon ceramic brake disc substrate, the ceramic coating may fall off during long-term use of the carbon ceramic brake disc with ceramic coating. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a carbon ceramic brake disc with ceramic coating and a preparation method thereof. By introducing carbon fiber tows in the direction perpendicular to the friction surface of the carbon ceramic brake disc substrate, the shear strength of the carbon ceramic brake disc substrate prepared by short fiber molding process in the direction parallel to the friction surface can be improved, and at the same time, the ceramic coating on the surface is connected to the substrate by the carbon fiber tows, so as to improve the adhesion between the ceramic coating on the surface of the carbon ceramic brake disc and the carbon ceramic brake disc substrate, and finally to improve the problem of easy cracking of the carbon ceramic brake disc prepared by short fiber molding process during long-term use, and the problem of easy falling off of the surface ceramic coating when preparing the carbon ceramic brake disc with ceramic coating.

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: The preparation method of a carbon ceramic brake disc with ceramic coating comprises the following steps: S1, preparation of a circular blank I: carbon fiber tows are inserted from the through hole on one side surface of a hard plastic plate and then taken out from the other side surface, and a certain length of the carbon fiber tows on the exit side is reserved. Then the hard plastic plate with the inserted carbon fiber tows is placed at the bottom of a cylindrical forming cavity mold, and the surface of the hard plastic plate on the exit side of the carbon fiber tows is directly in contact with the bottom of the mold. Then the mixed material is uniformly poured into the cylindrical mold cavity, and the amount of the poured mixed material is half of the amount of the mixed material required for the target blank thickness. Then the carbon fiber tows on the insertion side of the hard plastic plate are cut off at a height of 50-100mm above the loading amount formed by the added mixed material, and low-temperature molding is performed to obtain a circular blank I. S2. Preparation of circular ring blank II: Two circular ring blanks I that have completed low-temperature molding are stacked together and placed in a cylindrical mold, ensuring that the surfaces of the two blanks without hard plastic plates are in contact with each other and aligned. Then, a second high-temperature molding process is performed on them to obtain circular ring blank II. S3. Preparation of circular ring blank III: The circular ring blank II prepared in step S2 is carbonized under an inert atmosphere to obtain circular ring blank III. S4. Preparation of Circular Preform IV: After carbonizing the hard plastic plate on the upper and lower surfaces of Circular Preform III, the carbon debris formed will be removed. At this time, a groove of a certain depth will be formed on the upper and lower surfaces of Circular Preform III. Then, the carbon fiber bundles with a certain length reserved on the inner surface of the groove are straightened and arranged vertically along the surface of the groove. Then, the carbon fiber bundles that are higher than the groove depth are cut off to ensure that the height of the carbon fiber bundles is flush with the groove depth. The uniformly mixed slurry is poured evenly into one side of the groove of Circular Preform III, so that the liquid surface formed by the poured slurry is flush with the height of the groove. Then, it is cured. Then, the other side of Circular Preform III is cured with slurry according to the same operation process to obtain Circular Preform IV. S5. Preparation of carbon-ceramic brake disc: The circular blank IV is subjected to high-temperature vacuum silicon infiltration treatment, followed by subsequent machining treatment, to obtain a carbon-ceramic brake disc with ceramic coating.

[0008] In step S1, the thickness of the rigid plastic sheet is 2-4 mm, the diameter of the through holes on the surface of the rigid plastic sheet is 1-3 mm, and the areal density of the through holes is 1 per cm³. 2 ≤ρ≤4 pieces / cm 2 .

[0009] In step S1, the mixture comprises the following raw materials in the following mass percentages: 30-45 wt% short-cut carbon fiber, 25-45 wt% resin powder, 10-20 wt% silicon carbide powder, 10-20 wt% silicon powder, and 5-10 wt% carbon powder.

[0010] In step S1, the temperature of the low-temperature molding process is 50-80℃, the pressure is 1-4MPa, and the time is 0.5-1h.

[0011] In step S2, the high-temperature molding process is carried out at a temperature of 150-200℃, a pressure of 10-25MPa, and a time of 2-4h.

[0012] In step S3, the carbonization temperature is 800-1000℃, the holding time is 2-4h, and the heating rate of the carbonization process is 0.2-1℃ / min.

[0013] In step S4, the slurry comprises raw materials in the following mass proportions: 10-30wt% binder, 25-35wt% silicon carbide powder, 35-50wt% silicon powder, and 5-15wt% carbon powder; the binder is selected from phenolic resin or furan resin.

[0014] In step S4, the curing temperature is 150-200℃, and the holding time is 1-3h.

[0015] In step S5, the siliconizing temperature is 1500-1800℃, the holding time is 1-3h, the vacuum degree is ≤100Pa, and the amount of silicon powder added in the vacuum siliconizing is 1.1-1.2 times the total mass of the ring-shaped blank IV.

[0016] The application also provides a carbon-ceramic brake disc with a ceramic coating prepared by the above preparation method.

[0017] Compared with the prior art, the application has the following beneficial effects: (1) The carbon-ceramic brake disc substrate is prepared by introducing carbon fiber tows perpendicular to the friction surface direction in the short fiber molding process, which can effectively improve the interlayer shear strength of the carbon-ceramic brake disc in the longitudinal direction; at the same time, the carbon fiber tows can effectively connect the ceramic coating and the carbon-ceramic brake disc substrate together, further improving the adhesion between the ceramic coating and the carbon-ceramic brake disc substrate and reducing the risk of ceramic coating collapse.

[0018] (2) The technical solution provided by the application introduces a hard plastic plate during the molding process, which can effectively link the introduced longitudinal carbon fiber tows, and can be removed through subsequent high-temperature carbonization to form grooves with a certain thickness on the upper and lower surfaces of the formed ring-shaped blank II, facilitating the subsequent implementation of slurry coating pouring, eliminating the need for separate machining treatment for grooving in the existing preparation process, thereby reducing the cost. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 FIG. 1 is a schematic view of the longitudinal cross-sectional structure of the circular blank I provided by the application; BRIEF DESCRIPTION OF DRAWINGS 11: carbon fiber tow reserved section I; 12: mixed material blank; 13: carbon fiber tow; 14: hard plastic plate with through holes; 15: carbon fiber tow reserved section II. DETAILED DESCRIPTION

[0020] The application will be further described in detail below through specific preferred embodiments, but the application is not limited to the following embodiments.

[0021] It should be noted that, unless otherwise specified, all chemical reagents involved in this invention were purchased through commercial channels.

[0022] A method for preparing a carbon-ceramic brake disc with a ceramic coating includes the following steps: S1. Preparation of the circular ring blank I Regarding the preparation of the circular ring blank I, this invention combines... Figure 1 Please provide a detailed explanation.

[0023] S11. The mixture composed of short-cut carbon fibers, resin powder, silicon carbide powder, silicon powder, and carbon powder is mixed evenly. This mixture is used to prepare... Figure 1 The mixed preform 12 contains the following components in terms of mass percentage: 30-45 wt% chopped carbon fiber, 25-45 wt% resin powder, 10-20 wt% silicon carbide powder, 10-20 wt% silicon powder, and 5-10 wt% carbon powder.

[0024] The chopped carbon fibers range in length from 1 to 4 cm and have a specification of 5-12 K.

[0025] The resin powder can be selected from phenolic resin or epoxy resin, and is more preferably phenolic resin.

[0026] The particle size of silicon carbide powder is 200-1000 mesh.

[0027] The particle size of the silicon powder is 200-800 mesh.

[0028] The toner can be selected from carbon fiber powder, resin carbon, or graphite carbon, with a particle size of 300-1500 mesh.

[0029] S12. Prepare a rigid plastic plate 14 with through holes. Prepare a rigid plastic plate of a certain thickness that can be placed in the mold according to the shape of the mold. Ensure that the outer diameter D1 of the rigid plastic plate is smaller than the outer diameter D2 of the mold, and the inner diameter d1 of the rigid plastic plate is larger than the inner diameter d2 of the smaller side of the friction surface area of ​​the final carbon ceramic brake disc. A certain number of through holes are distributed on the surface of the rigid plastic plate.

[0030] Wherein, 3mm≤D2-D1≤6mm; 3mm≤d1-d2≤6mm.

[0031] The rigid plastic sheet can be made of PC material, with a thickness of 2-4mm. The diameter of the through holes on the surface of the rigid plastic sheet is 1-3mm, and the areal density of the through holes is 1 per cm³. 2 ≤ρ≤4 pieces / cm 2 .

[0032] S13, the carbon fiber tows 13 of a certain length of carbon fiber tows are inserted from the side of the through hole of the hard plastic plate surface, and then are pulled out from the other side of the hard plastic plate, so that the carbon fiber tows pulled out from the side have a certain length of carbon fiber tows pulled out, as shown in Figure 1 The length of the carbon fiber tows pulled out is defined as the carbon fiber tows segment II 15, so that when the hard plastic plate on the side of the carbon fiber tows pulled out contacts the bottom surface of the mold during the placement of the hard plastic plate in the mold, the carbon fiber tows segment II 15 pulled out is pressed by the hard plastic plate, preventing the carbon fiber tows from being pulled out of the through hole of the hard plastic plate during subsequent operations. In order to further ensure that the carbon fiber tows segment II 15 is not pulled out of the through hole of the hard plastic plate, the excess length of the carbon fiber tows pulled out can be bonded to the side of the hard plastic plate by glue.

[0033] The selected carbon fiber tows are 3-10K, and the length of the carbon fiber tows segment II is controlled to be 100-200mm.

[0034] S14, the mixed material uniformly mixed in step S11 is uniformly poured into the mold in which the hard plastic plate has been placed in advance, and in this process, the left and right distance between the outer circular side of the hard plastic plate and the outer circular side of the mold is kept consistent, and the carbon fiber tows on the side of the carbon fiber tows inserted are lifted vertically. The amount of mixed material poured is controlled to ensure that it can finally be pressed to a thickness of half the target green body, and then the carbon fiber tows above the initial mixed material height formed by the mixed material added are cut, and the length of the carbon fiber tows segment I 11 above the mixed material loading height is controlled to be 50-100mm.

[0035] S15, the mixed material poured into the mold above is low-temperature pressed once, the temperature of the once-pressed is 50-80℃, the pressure of the once-pressed is 1-4MPa, and the time is 0.5-1h, and finally the circular ring green body I is obtained as shown in Figure 1

[0036] S2, preparation of circular ring green body II The two circular ring green bodies I completed by once-pressing are stacked together for high-temperature secondary pressing, and the flat surfaces of the circular ring green bodies I without the hard plastic plate are ensured to be in contact, the temperature of the secondary pressing is 150-200℃, the pressure of the secondary pressing is 10-25MPa, and the mold pressing time is 2-4h, and finally the circular ring green body II is obtained.

[0037] S3, preparation of circular ring green body III ​The ring blank II obtained by the secondary forming is subjected to high-temperature carbonization treatment in an inert gas atmosphere, the carbonization treatment temperature is 800-1000℃, the holding time is 2-4h, the inert gas can be selected from N2 or Ar atmosphere, the heating rate of the carbonization process is controlled at 0.2-1℃ / min, and finally the ring blank III is obtained.

[0038] S4, preparation of the ring blank IV S41, the mixture composed of the binder, silicon carbide powder, silicon powder and carbon powder is uniformly mixed to form a slurry with a certain viscosity.

[0039] The binder is selected from resin liquid, for example, phenolic resin or furan resin can be selected.

[0040] The slurry includes raw materials with the following mass ratio: 10-30wt% binder, 25-35wt% silicon carbide powder, 35-50wt% silicon powder and 5-15wt% carbon powder.

[0041] The prepared slurry is diluted with ethanol to a viscosity of 40-100Pa·s.

[0042] The particle size of the silicon carbide powder is 200-1000 mesh.

[0043] The particle size of the silicon powder is 500-2000 mesh.

[0044] The carbon powder can be selected from resin carbon, graphite carbon or carbon fiber powder, and the particle size is 300-1000 mesh.

[0045] S42, the ring blank III obtained by high-temperature carbonization treatment is subjected to treatment before pouring the slurry. After the high-temperature carbonization treatment of the ring blank II, the hard plastic plates on the upper and lower surfaces will be carbonized, and some residual carbon chips will be formed on the surface of the ring blank III. Therefore, the residual carbon chips formed after the carbonization of the hard plastic plates are cleaned, a certain depth of grooves is formed on the surface of the ring blank III, and at the same time, a certain length of carbon fiber tows is exposed on the surface of the grooves. The carbon fiber tows on the surface of the grooves are straightened by hand, and the carbon fiber tows protruding above the groove depth are cut off to ensure that the height of the carbon fiber tows is flush with the groove depth.

[0046] S43, the uniformly mixed slurry is poured into one of the grooves of the ring blank III, and the pouring is stopped when the poured slurry just fills the entire groove. The ring blank III is subjected to solidification treatment, and after the solidification is completed, the other groove of the ring blank III is subjected to the same process treatment, and finally the ring blank IV with solidified coating on the upper and lower surfaces is obtained. The solidification temperature is 150-200℃, and the holding time is 1-3h.

[0047] S5, preparation of the carbon ceramic brake disc The ring body IV obtained through the coating curing treatment is subjected to high-temperature vacuum siliconizing treatment, the temperature of the siliconizing treatment is 1500-1800 DEG C, the vacuum degree is less than or equal to 100 Pa, the amount of silicon powder added in the vacuum siliconizing is 1.1-1.2 times of the total mass of the ring body IV, the holding time is 1-3 h, and in order to reduce the processing amount in the later stage, high-temperature vacuum evaporation siliconizing treatment is preferably adopted, that is, the ring body IV does not directly contact with molten silicon.

[0048] The ring body IV subjected to the high-temperature siliconizing treatment is subjected to grinding and polishing, inner circular step and rotating hole treatment (tightening bolt hole, surface ventilation hole, side ventilation groove) and other machining treatments, and finally the carbon ceramic brake disc with a ceramic coating required by the application can be obtained.

[0049] The application is further described below through specific examples, and the brand of the epoxy resin powder used in the examples of the application is NPES-607 (Dongguan Donglin High Polymer Material Co., Ltd.); the brand of the phenolic resin is PM-04 (Jinan Shengquan Group Co., Ltd.); and the resin carbon powder is obtained by using furan resin liquid (FA-2 type, Shijiazhuang Shiyi Furfuralcohol Co., Ltd.), high-temperature carbonization and then spherulitic graphite.

[0050] Example 1 A preparation method of a carbon ceramic brake disc with a ceramic coating, comprising the following steps: S1, preparation of a ring body I S11, a mixture composed of 45wt.% of chopped carbon fibers with a length of 1 cm and a specification of 12K, 25wt.% of epoxy resin powder, 20wt.% of silicon carbide powder with a particle size of 200 mesh, 5wt.% of silicon powder with a particle size of 800 mesh and 5wt.% of graphite carbon powder with a particle size of 1500 mesh is uniformly mixed by a stirrer for use; S12, the mold for forming is a cylindrical forming cavity with an outer diameter of 400 mm and an inner diameter of 180 mm, and the inner diameter of the smaller surface of the carbon ceramic brake disc prepared finally is 195 mm, at this time, a circular PC hard plastic plate with a thickness of 2 mm and an outer diameter of 395 mm and an inner diameter of 200 mm is selected, and a rotating hole is formed in the circular hard plastic plate to form a through hole with a hole diameter of 1 mm and a surface density of 1 per cm 2 ; S13, carbon fiber tows with a 3K tow are inserted from one side surface of the hard plastic plate through the through hole, and are pulled out from the other side surface, and a certain length of the carbon fiber tows pulled out from the other side surface is reserved, and the length of the carbon fiber tows pulled out from the other side surface is 100 mm; S14, put the hard plastic plate penetrating the carbon fiber tows into the bottom of the cylindrical cavity mold for molding, so that the outer diameter circumference of the hard plastic plate and the outer diameter circumference of the mold cavity are both 2 mm apart, and ensure that the hard plastic plate surface on the side where the carbon fiber tows penetrate out directly contacts the mold bottom, and the hard plastic plate itself under its own weight presses the carbon fiber tows of a certain length on the side where the hard plastic plate penetrates out on the mold bottom, so that the carbon fiber tows on the side where the hard plastic plate penetrates in are not easily pulled out, and then the carbon fiber tows on the side where the hard plastic plate penetrates in are vertically lifted to ensure that the carbon fiber tows are arranged in a direction perpendicular to the surface of the hard plastic plate; S15, pour the mixed material obtained in step S11 into the cylindrical mold cavity, and the amount of the mixed material poured is half of the amount of mixed material required to add according to the thickness of the target blank to be pressed finally, and then cut the carbon fiber tows on the side where the hard plastic plate penetrates in 50 mm above the height of the charge formed by the added mixed material; S16, perform low-temperature molding treatment on the mixed material poured into the cylindrical mold above, the molding temperature is 50℃, the pressure applied during molding is 4MPa, and the time is 1h, and finally obtain a circular ring blank I.

[0051] S2, preparation of circular ring blank II Place the two circular ring blanks I that have completed the low-temperature molding treatment together in a cylindrical mold, and ensure that the surfaces without hard plastic plates of the two are in contact with each other and aligned, and then perform secondary high-temperature molding treatment, the molding temperature is 150℃, the pressure applied during molding is 25MPa, and the time is 2h, and finally obtain a circular ring blank II.

[0052] S3, preparation of circular ring blank III Perform high-temperature carbonization treatment on the circular ring blank II obtained in step S2 under N2 atmosphere, the carbonization treatment temperature is 800℃, the holding time is 4h, and the heating rate during the carbonization stage is 1℃ / min, and finally obtain a circular ring blank III.

[0053] S4, preparation of circular ring blank IV S41, uniformly mix phenolic resin 30wt.%, carborundum powder with a particle size of 200 mesh 30wt.%, silicon powder with a particle size of 2000 mesh 35wt.%, and resin carbon powder with a particle size of 300 mesh 5wt.%, then add an appropriate amount of diluent ethanol, mix them uniformly through a blender, and prepare a slurry with a viscosity of 40Pa·s for use; S42, since the hard plastic plate will become carbon after high temperature carbonization, the carbon formed after carbonization of the hard plastic plate on the upper and lower surfaces of the ring blank III obtained after step S3 is cleaned, at this time the upper and lower surfaces of the ring blank III will form a certain depth of groove, then the inner surface of the groove is reserved a certain length of carbon fiber bundle, which is straightened and arranged in the vertical direction of the groove surface, then the carbon fiber bundle higher than the groove depth is cut off to ensure that the height of the carbon fiber bundle is flush with the groove depth; S43, the above mixed slurry is uniformly poured into one of the grooves of the ring blank III, so that the liquid surface formed by the poured slurry is flush with the height of the groove, then it is subjected to coating curing treatment, and the curing treatment temperature is 150℃, and the holding time is 3h; S44, after the groove of one side of the ring blank III is completed, the slurry coating curing treatment is carried out, and the other side of the ring blank III is subjected to slurry coating curing treatment according to the same operation process, and finally the ring blank IV is obtained.

[0054] S5, preparation of carbon ceramic brake disc The ring blank IV is subjected to high temperature vacuum silicon infiltration treatment, the treatment temperature is 1500℃, the holding time is 3 hours, the vacuum degree is 80Pa, and the amount of silicon powder added for infiltration is 1.2 times the total mass of the ring blank IV, wherein, during the silicon infiltration treatment, the ring blank IV and the molten silicon liquid are kept in a state of mutual non-contact, which can be achieved by raising the ring blank IV with graphite blocks to separate the molten silicon liquid, and finally the ceramicization treatment of the ring blank IV is realized; then the ring blank IV after ceramicization treatment is subjected to subsequent machining treatment, and a carbon ceramic brake disc with ceramic coating is obtained.

[0055] Example 2 A preparation method of a carbon ceramic brake disc with ceramic coating, comprising the following steps: S1, preparation of ring blank I S11, the mixture composed of 30wt.% of chopped carbon fiber with a length of 4cm and a specification of 5K, 35wt.% of phenolic resin powder, 5wt.% of silicon carbide powder with a particle size of 1000 mesh, 20wt.% of silicon powder with a particle size of 200 mesh, and 5wt.% of resin carbon powder with a particle size of 300 mesh is uniformly mixed by a stirrer for use; S12, the mold for forming is a cylindrical cavity with an outer diameter of 400 mm and an inner diameter of 180 mm, and the inner diameter of the carbon ceramic brake disc friction surface area with a smaller area is 195 mm. At this time, a circular PC hard plastic plate with a thickness of 4 mm and an outer diameter of 394 mm and an inner diameter of 201 mm is selected, and a through hole is drilled in the circular hard plastic plate. The diameter of the through hole is 3 mm, and the surface density of the hole is 2.5 holes / cm 2 ; S13, carbon fiber tows with a tow of 10K are inserted from one side surface of the hard plastic plate through the through hole, and are pulled out from the other side surface, and the length of the carbon fiber tows pulled out from the other side surface is reserved. The length of the carbon fiber tows pulled out from the other side surface is 200 mm; S14, the hard plastic plate with carbon fiber tows inserted is placed at the bottom of the cylindrical cavity mold for forming, so that the distance between the outer diameter circumference of the hard plastic plate and the outer diameter circumference of the mold cavity is 3 mm, and the surface of the hard plastic plate on the side where the carbon fiber tows are pulled out is in direct contact with the bottom of the mold. The carbon fiber tows with a certain length reserved on the side where the hard plastic plate is pulled out are pressed on the bottom of the mold by the self-weight of the hard plastic plate, so that the carbon fiber tows on the side where the hard plastic plate is pulled in are not easily pulled out. Then, the carbon fiber tows on the side where the hard plastic plate is pulled in are vertically lifted to ensure that the carbon fiber tows are arranged in a direction perpendicular to the surface of the hard plastic plate; S15, the mixed material prepared in step S11 is uniformly poured into the cylindrical mold cavity, and the amount of the poured mixed material is half of the amount of the mixed material required for the target green body thickness of the final pressing. Then, the carbon fiber tows on the side where the hard plastic plate is pulled in are cut off at a height of 100 mm above the height of the material formed by the added mixed material; S16, the cylindrical mold mixed material poured above is subjected to low-temperature molding treatment, the molding temperature is 80℃, the pressure applied during molding is 1MPa, and the time is 0.5h. Finally, a circular ring green body I is obtained.

[0056] S2, preparation of circular ring green body II The two circular ring green bodies I subjected to low-temperature molding treatment are stacked together and placed in a cylindrical mold, and the surfaces of the two circular ring green bodies I without hard plastic plates are in contact with each other and aligned. Then, the two circular ring green bodies I are subjected to secondary high-temperature molding treatment, the molding temperature is 200℃, the pressure applied during molding is 10MPa, and the time is 4h. Finally, a circular ring green body II is obtained.

[0057] S3, preparation of circular ring green body III The circular ring green body II obtained in step S2 is subjected to high-temperature carbonization treatment in an Ar atmosphere, the carbonization treatment temperature is 1000℃, the holding time is 2h, and the heating rate during the carbonization stage is 0.2℃ / min. Finally, a circular ring green body III is obtained.

[0058] S4, preparation of the ring blank IV S41, 10wt.% of furan resin, 25wt.% of SiC powder with a particle size of 1000 mesh, 50wt.% of Si powder with a particle size of 500 mesh, and 15wt.% of graphite powder with a particle size of 300 mesh are uniformly mixed, then an appropriate amount of diluent ethanol is added, and they are uniformly mixed by a blender to prepare a slurry with a viscosity of 100 Pa·s for use; S42, since the hard plastic plate will become carbon after high-temperature carbonization, the carbon formed after carbonization of the hard plastic plate on the upper and lower surfaces of the ring blank III obtained after step S3 is cleaned, at this time a certain depth of groove is formed on the upper and lower surfaces of the ring blank III, then the carbon fiber tows reserved on the inner surface of the groove are straightened to arrange them in the vertical direction of the groove surface, and then the carbon fiber tows protruding above the groove depth are cut off to ensure that the height of the carbon fiber tows is flush with the groove depth; S43, the above uniformly mixed slurry is uniformly poured into one of the grooves of the ring blank III, so that the liquid surface formed by the poured slurry is flush with the height of the groove, then it is subjected to coating and curing treatment, and the curing treatment temperature is 200℃, and the holding time is 1h; S44, after the coating and curing treatment of the slurry in one of the grooves of the ring blank III is completed, the other side of the ring blank III is subjected to coating and curing treatment of the slurry according to the same operation process, and finally the ring blank IV is obtained.

[0059] S5, preparation of the carbon ceramic brake disc The ring blank IV is subjected to high-temperature vacuum silicon infiltration treatment, the treatment temperature is 1800℃, the holding time is 1 hour, the vacuum degree is 100Pa, and the amount of silicon powder added for infiltration is 1.0 times the total mass of the ring blank IV, wherein during the silicon infiltration treatment, the ring blank IV and the molten silicon liquid are kept in a state of mutual non-contact, which can be achieved by raising the ring blank IV with graphite pads to separate it from the molten silicon liquid, and finally the ceramicization treatment of the ring blank IV is realized; then the ring blank IV after the ceramicization treatment is subjected to subsequent machining treatment, and a carbon ceramic brake disc with a ceramic coating is obtained.

[0060] Example 3 A preparation method of a carbon ceramic brake disc with a ceramic coating, comprising the following steps: S1, preparation of the ring blank I S11, the mixture of 35wt.% of 3cm long and 8K specification short carbon fiber, 30wt.% of phenolic resin powder, 12wt.% of 500 mesh size silicon carbide powder, 15wt.% of 400 mesh size silicon powder and 8wt.% of 500 mesh size carbon fiber powder is mixed uniformly by a blender and is ready for use; S12, the mold for forming is a cylindrical forming cavity with an outer diameter of 400mm and an inner diameter of 180mm, and the inner diameter of the smaller friction surface area of the finally prepared carbon ceramic brake disc is 195mm. At this time, a circular ring PC hard plastic plate with a thickness of 4mm and an outer diameter of 396mm and an inner diameter of 199mm is selected, and a through hole is drilled in the circular ring hard plastic plate to form a through hole with a hole diameter of 2mm and a hole surface density of 4 / cm 2 S13, the carbon fiber tows with a tow of 7K are inserted from one side surface of the hard plastic plate through the through hole and are pulled out from the other side surface, and a certain length of the carbon fiber tows pulled out from the other side surface is reserved. The length of the carbon fiber tows pulled out from the other side surface is 150mm; S14, the hard plastic plate with the inserted carbon fiber tows is placed at the bottom of the cylindrical forming cavity mold for forming, so that the distance between the outer diameter circumference of the hard plastic plate and the outer diameter circumference of the mold cavity is 2mm, and the surface of the hard plastic plate on the side where the carbon fiber tows are pulled out is directly in contact with the bottom of the mold. The carbon fiber tows with a certain length reserved on the side where the hard plastic plate is pulled out are pressed on the bottom of the mold by the self-weight of the hard plastic plate, so that the carbon fiber tows on the side where the hard plastic plate is inserted are not easily pulled out. Then, the carbon fiber tows on the side where the hard plastic plate is inserted are vertically lifted to ensure that the carbon fiber tows are arranged in a direction perpendicular to the surface of the hard plastic plate; S15, the mixed material in step S11 is uniformly poured into the cylindrical mold cavity, and the amount of the poured mixed material is half of the amount of the mixed material required for the target thickness of the finally required compact. Then, the carbon fiber tows on the side where the hard plastic plate is inserted are cut off at a height of 70mm above the height of the added mixed material; S16, the poured mixed material in the cylindrical mold is subjected to low-temperature molding treatment, the molding temperature is 60℃, the pressure applied during molding is 2.5MPa, and the time is 0.7h. Finally, a circular ring compact I is obtained.

[0061] S2, preparation of circular ring compact II The two circular ring compacts I subjected to low-temperature molding treatment are stacked together and placed in a cylindrical mold, and the surfaces without hard plastic plates of the two compacts are in contact with each other and are aligned. Then, the two compacts are subjected to secondary high-temperature molding treatment, the molding temperature is 180℃, the pressure applied during molding is 18MPa, and the time is 2.5h. Finally, a circular ring compact II is obtained. ​

[0062] S3, preparation of the ring blank III The ring blank II prepared in step S2 is subjected to high-temperature carbonization treatment under an Ar atmosphere, the carbonization treatment temperature is 900°C, the holding time is 3h, and the carbonization stage heating rate is 0.5°C / min, and finally the ring blank III is obtained.

[0063] S4, preparation of the ring blank IV S41, phenolic resin 20wt.%, SiC powder with a particle size of 800 mesh 30wt.%, Si powder with a particle size of 1200 mesh 40wt.% and graphite powder with a particle size of 600 mesh 10wt.% are uniformly mixed, then an appropriate amount of diluent ethanol is added, and they are uniformly mixed by a stirrer to prepare a slurry with a viscosity of 60Pa·s for use; S42, since the hard plastic plate will become carbon after high-temperature carbonization, the carbon formed after carbonization of the hard plastic plate on the upper and lower surfaces of the ring blank III obtained after step S3 is cleaned, at this time a certain depth of groove will be formed on the upper and lower surfaces of the ring blank III, then the groove inner surface itself is reserved a certain length of carbon fiber tows, which are straightened and arranged in the vertical direction of the groove surface, and then the carbon fiber tows protruding above the groove depth are cut off to ensure that the height of the carbon fiber tows is flush with the groove depth; S43, the above uniformly mixed slurry is uniformly poured into one of the grooves of the ring blank III, so that the liquid surface formed by the poured slurry is flush with the height of the groove, and then it is subjected to coating and curing treatment, the curing treatment temperature is 175°C, and the holding time is 1.5h; S44, after the groove of one side of the ring blank III is completed with slurry coating and curing treatment, the other side of the ring blank III is subjected to slurry coating and curing treatment according to the same operation process, and finally the ring blank IV is obtained.

[0064] S5, preparation of the carbon ceramic brake disc The ring blank IV is subjected to high-temperature vacuum silicon infiltration treatment, the treatment temperature is 1650°C, the holding time is 1.5h, the vacuum degree is 50Pa, and the amount of silicon powder added for infiltration is 1.1 times the total mass of the ring blank IV, wherein during the silicon infiltration treatment, the ring blank IV and the molten silicon liquid are kept in a state of mutual non-contact, which can be achieved by raising the ring blank IV with graphite pads to separate it from the molten silicon liquid, and finally the ceramicization treatment of the ring blank IV is realized; then the ring blank IV after ceramicization treatment is subjected to subsequent machining treatment, and a carbon ceramic brake disc with a ceramic coating is obtained.

[0065] Comparative Example 1 Compared with Example 1, the through hole on the surface of the hard plastic plate was not opened and the subsequent carbon fiber tows were not inserted in the preparation of the torus blank of Comparative Example 1, and the subsequent additional process caused by the introduction of the carbon fiber tows was omitted. The other preparation processes and process parameters remained the same.

[0066] Comparative Example 2 Compared with Example 2, except that the carbon fiber tows reserved in the groove of the torus blank III were all cut along the groove bottom plane during the preparation of the torus blank IV, that is, the cured coating prepared subsequently was not connected to the torus blank III by the carbon fiber tows, and the other preparation processes and process parameters remained the same.

[0067] Comparative Example 3 Compared with Example 3, the surface hole density of the hard plastic plate was designed to be 6 / cm2 during the process of punching the through hole on the hard plastic plate. 2 The other preparation processes and process parameters remained the same.

[0068] The carbon ceramic brake discs prepared in Examples 1-3 and Comparative Examples 1-3 were tested for performance, as follows: Shear strength test: according to ASTM D2344 / D2344M-13 (Standard Test Method for Apparent Interlaminar Shear Strength of Fiber Reinforced Polymer Matrix Composites by Short-Beam Method).

[0069] Bonding strength test: according to the Standard Test Method for Bonding Strength of Ceramic Coatings in ASTM C1624.

[0070] The test results are shown in Table 1.

[0071] Table 1 Performance test results of different groups Interlaminar shear strength of carbon ceramic brake disc substrate (MPa) Bonding strength between ceramic coating and carbon ceramic substrate (MPa) Microcrack state of ceramic coating surface Example 1 13.7 17.2 Good Comparative Example 1 8.5 10.6 Good Example 2 17.4 22.3 Good Comparative Example 2 17.4 18.7 Good Example 3 16.9 21.2 Good Comparative Example 3 18.8 23.5 Poor The test results are analyzed as follows: firstly, for example 1 and comparative example 1, it can be found that when the longitudinal carbon fiber tows are not introduced into the carbon ceramic brake disc substrate, the interlaminar shear strength of the substrate decreases obviously; meanwhile, when the carbon ceramic coating and the substrate are not connected together by the carbon fiber tows, the bonding strength between them also decreases obviously, which is also proved by example 2 and comparative example 2; for example 3 and comparative example 3, it can be found that when the number of introduced carbon fiber tows increases, the bonding strength between the carbon ceramic brake disc substrate, the carbon ceramic brake disc substrate and the ceramic coating can be further improved, but when the carbon fiber tows are too much, the microcrack state of the surface ceramic coating is easily deteriorated due to the large difference in the thermal expansion coefficient between the carbon fiber tows and the ceramic coating, thus the surface tow density of the carbon fiber tows connecting the carbon ceramic brake disc substrate and the ceramic coating on the surface thereof is controlled to be ≤4 tows / cm 2 .

[0072] Finally, it should be noted that the above examples do not limit the present application in any form. For those skilled in the art, some modifications and improvements can be made on the basis of the present application. Therefore, any modification or improvement made without departing from the spirit of the present application shall fall within the scope of the present application.

Claims

1. A method for preparing a carbon-ceramic brake disc with a ceramic coating, characterized in that, Includes the following steps: S1. Preparation of the circular ring blank I: The carbon fiber bundle is inserted through the through hole on one side of the rigid plastic plate and exits from the other side, ensuring that a certain length of the carbon fiber bundle is reserved on the exiting side. Then, the rigid plastic plate with the carbon fiber bundle inserted is placed at the bottom of the cylindrical forming cavity mold, ensuring that the surface of the rigid plastic plate on the exiting side of the carbon fiber bundle is in direct contact with the bottom of the mold. The mixed material is then poured evenly into the cylindrical mold cavity, and the amount of mixed material poured in is half of the amount of mixed material required for the target blank thickness. Then, the carbon fiber bundle on the side of the rigid plastic plate inserted is cut at a height of 50-100 mm above the height of the filling material formed by the added mixed material. The blank is then subjected to low temperature molding treatment to obtain the circular ring blank I. S2. Preparation of circular ring blank II: Two circular ring blanks I that have completed low-temperature molding are stacked together and placed in a cylindrical mold, ensuring that the surfaces of the two blanks without hard plastic plates are in contact with each other and aligned. Then, a second high-temperature molding process is performed on them to obtain circular ring blank II. S3. Preparation of circular ring blank III: The circular ring blank II prepared in step S2 is carbonized under an inert atmosphere to obtain circular ring blank III. S4. Preparation of Circular Preform IV: After carbonizing the hard plastic plate on the upper and lower surfaces of the circular preform III, the carbon debris formed is removed. At this time, a groove of a certain depth will be formed on the upper and lower surfaces of the circular preform III. Then, the carbon fiber bundles with a certain length reserved on the inner surface of the groove are straightened and arranged vertically along the surface of the groove. Then, the carbon fiber bundles that are higher than the groove depth are cut off to ensure that the height of the carbon fiber bundles is flush with the groove depth. The uniformly mixed slurry is poured evenly into one side of the groove of the circular preform III, so that the liquid surface formed by the poured slurry is flush with the height of the groove. Then, it is cured. Then, the other side of the circular preform III is cured with slurry according to the same operation process to obtain the circular preform IV. S5. Preparation of carbon-ceramic brake disc: The circular blank IV is subjected to high-temperature vacuum silicon infiltration treatment, followed by subsequent machining treatment, to obtain a carbon-ceramic brake disc with ceramic coating.

2. The preparation method according to claim 1, characterized in that, In step S1, the thickness of the rigid plastic sheet is 2-4 mm, the diameter of the through holes on the surface of the rigid plastic sheet is 1-3 mm, and the areal density of the through holes is 1 per cm³. 2 ≤ρ≤4 pieces / cm 2 .

3. The preparation method according to claim 1, characterized in that, In step S1, the mixture comprises the following raw materials in the following mass percentages: 30-45 wt% short-cut carbon fiber, 25-45 wt% resin powder, 10-20 wt% silicon carbide powder, 10-20 wt% silicon powder, and 5-10 wt% carbon powder.

4. The preparation method according to claim 1, characterized in that, In step S1, the temperature of the low-temperature molding process is 50-80℃, the pressure is 1-4MPa, and the time is 0.5-1h.

5. The preparation method according to claim 1, characterized in that, In step S2, the high-temperature molding process is carried out at a temperature of 150-200℃, a pressure of 10-25MPa, and a time of 2-4h.

6. The preparation method according to claim 1, characterized in that, In step S3, the carbonization temperature is 800-1000℃, the holding time is 2-4h, and the heating rate of the carbonization process is 0.2-1℃ / min.

7. The preparation method according to claim 1, characterized in that, In step S4, the slurry comprises the following raw materials in the following mass percentages: 10-30 wt% binder, 25-35 wt% silicon carbide powder, 35-50 wt% silicon powder, and 5-15 wt% carbon powder; the binder is selected from phenolic resin or furan resin.

8. The preparation method according to claim 1, characterized in that, In step S4, the curing temperature is 150-200℃, and the holding time is 1-3 hours.

9. The preparation method according to claim 1, characterized in that, In step S5, the temperature of silicon infiltration is 1500-1800℃, the holding time is 1-3h, the vacuum degree is ≤100Pa, and the amount of silicon powder added in vacuum silicon infiltration is 1.1-1.2 of the total mass of the annular preform IV.

10. A carbon ceramic brake disc with a ceramic coating prepared by the preparation method according to any one of claims 1-9.

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