Carbon ceramic brake disc with double-layer friction layer and preparation method thereof

Abstract

The application provides a carbon ceramic brake disc with double friction layers, which comprises a base layer and a friction layer, the friction layer comprises a first friction layer and a second friction layer, and the first friction layer is located between the base layer and the second friction layer. The content of silicon carbide in the first friction layer is 50-80 vol%, and the content of silicon is 20-50 vol%; the content of silicon carbide in the second friction layer is 70-95 vol%, and the content of silicon is 5-30 vol%. By setting two friction layers, the outermost friction layer is the second friction layer, the second friction layer has high content of silicon carbide, large thermal expansion coefficient and large particle size, and has good wear resistance; the inner friction layer is the first friction layer, the content of silicon carbide in the first friction layer is lower than that in the second friction layer, and the first friction layer has a lower thermal expansion coefficient, which effectively alleviates the stress concentration problem caused by the connection between the high-silicon carbide friction layer and the base.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of brake disc manufacturing, and particularly relates to a carbon ceramic brake disc with double-layer friction layer and a preparation method thereof. BACKGROUND

[0002] The brake disc mainly plays a role in reducing speed or emergency stopping in the operation of the automobile, and is related to the safety of human life in the event of an emergency, and is therefore particularly important. Since the brake generates a large impact friction force for a short time and generates a large amount of heat energy, the material of the brake disc should have the properties of heat resistance, impact resistance, fatigue resistance, high strength and the like. The Cf / SiC composite material can be used as a brake part in the aviation and high-end automobile industries due to its high hardness, excellent friction performance and the ability to greatly reduce the mass of the friction braking material. The carbon ceramic brake disc combines the physical properties of carbon fiber and polycrystalline silicon carbide. The breaking elongation of C / SiC material is from 0.1% to 0.3%, which is a very high value for ceramic materials. At the same time, due to the characteristics of light weight, good hardness, stability under high pressure and high temperature conditions, heat shock resistance and the same ductile shear fracture characteristics, the service life of the brake disc is prolonged, and most of the problems caused by the load are avoided.

[0003] The preparation process of the carbon ceramic brake disc at present is needle punching-carburization-high temperature treatment-chemical vapor deposition-high temperature treatment-application of friction layer-processing-silicon infiltration-processing, wherein the application of the friction layer is to improve the wear resistance of the brake disc and stabilize the friction coefficient. The friction layer and the silicon carbide content and the fiber content of the brake disc are very different. Since the wear resistance of the friction layer is required to be high, the friction layer does not contain carbon fiber and the content of silicon carbide is more than 80%, which leads to a large difference in the thermal expansion coefficient between the friction layer and the matrix, and there is a large residual stress in the friction layer during the cooling process, which causes the friction layer to easily peel off during use. In view of this, the carbon ceramic brake disc with double-layer friction layer is provided to improve the combination of the friction layer and the matrix layer. SUMMARY

[0004] The present application aims to provide a carbon ceramic brake disc with double-layer friction layer and a preparation method thereof. By setting two layers of friction layer, the thickness of the friction layer is optimized, the bonding force between the friction layer and the matrix is improved, the joint strength between the friction layer and the matrix layer is effectively improved, and the wear resistance of the brake disc is improved.

[0005] To achieve this purpose, the present application provides a carbon ceramic brake disc with double-layer friction layer, which comprises a matrix layer and a friction layer, the friction layer comprises a first friction layer and a second friction layer, the first friction layer is located between the matrix layer and the second friction layer; the thickness of the first friction layer is , the content of silicon carbide is , and the content of silicon is ; the thickness of the second friction layer is , silicon carbide content is , the silicon content is , then the thickness of the second friction layer Satisfies the following formula:

[0006]

[0007] The coefficient β is set to 0.9 or 5, ΔT is the difference between the siliconizing temperature and the room temperature, and ΔT is 1600K.

[0008] Preferably, the silicon carbide content in the first friction layer is 50-80 vol%, and the silicon content is 20-50 vol%; the silicon carbide content in the second friction layer is 70-95 vol%, and the silicon content is 5-30 vol%.

[0009] Preferably, the first friction layer comprises coarse silicon carbide with a particle size of 40-80 microns and fine silicon carbide with a particle size of 0.5-30 microns.

[0010] Preferably, the volume ratio of the coarse silicon carbide to the fine silicon carbide is 1:1-10:1.

[0011] Preferably, the second friction layer comprises a second coarse silicon carbide with a particle size of 80-150 microns and a second fine silicon carbide with a particle size of 0.5-30 microns.

[0012] Preferably, the volume ratio of the second coarse silicon carbide to the second fine silicon carbide is 1:1-10:1.

[0013] The present invention also provides a method for preparing a carbon-ceramic brake disc having a double friction layer, which comprises the following steps:

[0014] S1: Repeatedly overlap the carbon fiber unidirectional cloth and the carbon fiber mesh to obtain a carbon fiber preform. Each layer of carbon fiber unidirectional cloth and each layer of carbon fiber mesh are stacked and then needle-punched. The needle-punching density is 50-200 needles / cm 2 ,The carbon fiber directions between the two adjacent carbon fiber unidirectional fabrics above and below each carbon fiber mesh form an angle of 90°;

[0015] S2: impregnating the carbon fiber preform into a 40 wt% phenolic resin alcohol solution, and drying the preform until the alcohol is completely volatilized to obtain an impregnated body;

[0016] S3: Carbonizing the impregnated body to obtain a carbonized body at a carbonization temperature of 900° C. for 6 hours;

[0017] S4: subjecting the carbonized body to a low-temperature graphitization treatment in nitrogen to obtain a graphitized body, the treatment temperature being 1700° C. and the temperature being kept for 2 hours;

[0018] S5: mixing the silicon carbide powder and phenolic powder uniformly to obtain a first friction layer pressing powder, uniformly laying the first friction layer pressing powder on the graphitized compact, pressing at a temperature of 90°C for 30 min to obtain a first compact, the pressure being greater than 10 MPa;

[0019] S6: mixing the silicon carbide powder and phenolic powder uniformly to obtain a second friction layer pressing powder, uniformly laying the second friction layer pressing powder on the first compact, pressing at a temperature of 150°C for 60 min to completely solidify to obtain a second compact, the pressure being greater than 10 MPa;

[0020] S7: machining the second compact to obtain a brake disc compact;

[0021] S8: placing the brake disc compact into a boron nitride crucible and then into a high-temperature vacuum furnace for siliconizing treatment, after the siliconizing treatment, performing surface grinding and size processing to obtain the carbon ceramic brake disc with a double-layer friction layer, the boron nitride crucible being previously placed with pure silicon powder with a mass of 1.1 times the mass of the compact, the siliconizing treatment temperature being 1600-1700°C, the holding time being 2-4 h, and the furnace pressure being less than 1000 Pa.

[0022] Preferably, the steps S2 and S3 are performed at least once, so that the density of the carbonized body reaches 1.25-1.45 g / cm 3 .

[0023] Preferably, in the first friction layer pressing powder, the particle size of the silicon carbide is 40-80 microns, the content of the silicon carbide powder is 35-55 vol%, and the content of the phenolic powder is 45-65 vol%.

[0024] Preferably, in the second friction layer pressing powder, the particle size of the silicon carbide is 80-150 microns, the content of the silicon carbide powder is 45-75 vol%, and the content of the phenolic powder is 25-55 vol%.

[0025] Beneficial effects: the carbon ceramic brake disc with double friction layers provided by the application has the following beneficial effects: two layers of friction layers are arranged, the outermost friction layer is the second friction layer, the second friction layer has high silicon carbide content, a large thermal expansion coefficient and a large particle size, and has good wear resistance, the inner friction layer is the first friction layer, the silicon carbide content of the first friction layer is lower than that of the second friction layer, and the first friction layer has a lower thermal expansion coefficient, which effectively alleviates the stress concentration problem caused by the connection of the high-silicon carbide friction layer and the substrate, thereby avoiding the separation of the friction layer and the substrate layer due to stress concentration in the working state. Further, a relationship formula of the silicon carbide content, the silicon content and the thickness between the first friction layer and the second friction layer is established, the preferred range of the thickness of the second friction layer under different conditions can be obtained, the bonding force between the friction layer and the substrate layer is improved by adjusting the thickness of the friction layer, which not only improves the wear resistance of the brake disc but also prevents the friction layer from separating, achieving a win-win situation. According to the relationship formula, the theoretical thickness range of the second friction layer is calculated by detecting the silicon carbide content, the silicon content, the actual thickness value of the first friction layer and the silicon carbide content and the silicon content of the second friction layer during the production process, and the actual value of the second friction layer is compared with the theoretical value of the thickness of the friction layer, which can assist the technical personnel to judge the qualification of the brake disc and reduce the detection difficulty.

[0026] The application further provides a preparation method of the carbon ceramic brake disc with double friction layers, and the carbonization treatment is followed by twice pressing, and different content of silicon carbide powder and phenolic powder mixed pressing powder is used for each pressing, so that the manufacturing of the two layers of friction layers is realized, the pressing temperature of the outer friction layer is higher, and the pressing time is longer, and the two-step pressing is beneficial to improving the connection strength between the two layers of friction layers and the substrate and reducing the probability of separation of the friction layer and the substrate layer. The whole preparation process is simple in manufacturing method, does not need chemical vapor deposition treatment, uses low-temperature graphite conversion, and has simple process and low process difficulty, and is easy to scale production. DETAILED DESCRIPTION

[0027] The embodiments described below are only part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the application.

[0028] The embodiment provides a carbon ceramic brake disc with double friction layers, which comprises a substrate layer and a friction layer, the friction layer comprises a first friction layer and a second friction layer, the first friction layer is located between the substrate layer and the second friction layer; the thickness of the first friction layer is , the silicon carbide content is , and the silicon content is ; the thickness of the second friction layer is , the silicon carbide content is , and the silicon content is the thickness of the second friction layer is satisfies the following formula:

[0029]

[0030] wherein the coefficient β is 0.9 or 5, ΔT is the difference between the siliconizing temperature and the room temperature, and ΔT is 1600K.

[0031] The silicon carbide content in the first friction layer is 50-80 vol%, and the silicon content is 20-50 vol%; the silicon carbide content in the second friction layer is 70-95 vol%, and the silicon content is 5-30 vol%.

[0032] The first friction layer comprises coarse silicon carbide with a particle size of 40-80 microns and fine silicon carbide with a particle size of 0.5-30 microns.

[0033] The volume ratio of the coarse silicon carbide and the fine silicon carbide is 1:1-10:1. The volume ratio of the coarse silicon carbide and the fine silicon carbide includes but is not limited to 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, and 10:1. Further preferably, the volume ratio of the coarse silicon carbide and the fine silicon carbide is selected to be 2:1 or 3:1 or 4:1 or 5:1 or 6:1, because the mixing of coarse / fine silicon carbide has a higher packing density (fine powder exists between the gaps of coarse powder, and the packing density is high) in this ratio range.

[0034] The second friction layer comprises second coarse silicon carbide with a particle size of 80-150 microns and second fine silicon carbide with a particle size of 0.5-30 microns.

[0035] The volume ratio of the second coarse silicon carbide and the second fine silicon carbide is 1:1-10:1. The volume ratio of the second coarse silicon carbide and the second fine silicon carbide includes but is not limited to 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, and 10:1. Further preferably, the volume ratio of the coarse silicon carbide and the fine silicon carbide is selected to be 2:1 or 3:1 or 4:1 or 5:1 or 6:1.

[0036] The application also provides a preparation method of a carbon ceramic brake disc with a double-layer friction layer, for preparing the carbon ceramic brake disc with a double-layer friction layer as described above, comprising the following steps:

[0037] S1: repeatedly overlapping carbon fiber unidirectional cloth and carbon fiber tire to obtain a carbon fiber preform, and performing needle punching treatment on each layer of carbon fiber unidirectional cloth and each layer of carbon fiber tire after stacking, the needle punching density being 50-200 needles / cm 2 , the carbon fiber directions between the upper and lower two carbon fiber unidirectional cloths of each carbon fiber tire being at an angle of 90°;

[0038] S2: the carbon fiber preform is dipped in a 40wt% concentration of phenolic resin alcohol solution, and after dipping, drying treatment is performed until the alcohol is completely volatilized to obtain an impregnated body, the dipping time is generally 2-5h, preferably 3-4h, and the dipping time is selected based on the impregnation of the carbon fiber preform;

[0039] S3: the impregnated body is subjected to carbonization treatment to obtain a carbonized body, the carbonization temperature is 900℃, and the holding time is 6h;

[0040] S4: the carbonized body is subjected to low-temperature graphitization treatment in nitrogen to obtain a graphitized body, the treatment temperature is 1700℃, and the holding time is 2h;

[0041] S5: silicon carbide powder and phenolic powder are uniformly mixed to obtain first friction layer pressing powder, the first friction layer pressing powder is uniformly laid on the graphitized body, and pressing is performed at a temperature of 90℃ for 30min to obtain a first body, and the pressure is greater than 10MPa;

[0042] S6: silicon carbide powder and phenolic powder are uniformly mixed to obtain second friction layer pressing powder, the second friction layer pressing powder is uniformly laid on the first body, and pressing is performed at a temperature of 150℃ for 60min to completely solidify to obtain a second body, and the pressure is greater than 10MPa;

[0043] S7: the second body is subjected to mechanical processing to obtain a brake disc body;

[0044] S8: the brake disc body is placed in a boron nitride crucible and then placed in a high-temperature vacuum furnace for siliconizing treatment, after the siliconizing treatment is completed, surface grinding and size processing are performed to obtain the carbon ceramic brake disc with a double-layer friction layer, the boron nitride crucible is pre-filled with pure silicon powder with a mass of 1.1 times the mass of the body, the siliconizing treatment temperature is 1600-1700℃, the holding time is 2-4h, and the furnace pressure is less than 1000Pa.

[0045] S2 and S3 steps are performed at least once, so that the density of the carbonized body reaches 1.25-1.45g / cm 3 .

[0046] The particle size of silicon carbide in the first friction layer pressing powder is 40-80 microns, the content of silicon carbide powder is 35-55vol%, and the content of phenolic powder is 45-65vol%.

[0047] The particle size of silicon carbide in the second friction layer pressing powder is 80-150 microns, the content of silicon carbide powder is 45-75vol%, and the content of phenolic powder is 25-55vol%.

[0048] The stress formula between the first friction layer and the second friction layer is as follows:

[0049]

[0050] E is the Young's modulus, P is the Poisson's ratio;

[0051] For the interface of the first friction layer and the second friction layer, the residual stress of the interface due to the mismatch of the thermal expansion coefficient is:

[0052]

[0053] where E fr1 is the Young's modulus of the first friction layer, P fr1 is the Poisson's ratio of the first friction layer, t fr1 is the thickness of the first friction layer;

[0054] E fr2 is the Young's modulus of the second friction layer, P fr2 is the Poisson's ratio of the second friction layer, t fr2 is the thickness of the second friction layer.

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061] Substituting the above equation into the equation (1) gives:

[0062]

[0063] Thus, we have:

[0064]

[0065] where, is 1600k, should be between 20-60MPa, if the second friction layer is too thin, large residual stress will occur, and the friction layer will peel off. The experimental measurement shows that the residual stress of the friction layer between 20-60MPa will cause the friction layer to crack. In order to avoid cracking, we calculate the minimum residual stress value:

[0066]

[0067] Multiply the above formula by the coefficient β, the thickness calculated by the formula without the empirical coefficient 0.9-5 is the thickness of the friction layer when the residual stress is within a limited range (i.e. no cracks appear), while in the preparation process, local stress concentration caused by micro defects will lead to cracking, which is difficult to avoid, therefore we increase the coefficient β, that is, the second friction layer thickness calculated within the maximum and minimum range of β can better guarantee the strength of the friction layer, even in the case of cracks, it is not easy to cause the friction layer to crack.

[0068] If the thickness of the second friction layer is too thick, not only the weight of the brake disc is increased, but also the second friction layer is prone to peeling under the action of shear force in friction, therefore the maximum value of the second friction layer is not more than 10mm.

[0069] Example 1

[0070] The present embodiment provides a carbon ceramic brake disc with a double-layer friction layer, and the preparation steps of the carbon ceramic brake disc with a double-layer friction layer are as follows:

[0071] S1: repeatedly overlap carbon fiber unidirectional cloth and carbon fiber tire to obtain a carbon fiber preform, after each layer of carbon fiber unidirectional cloth and each layer of carbon fiber tire are overlapped, needle punching treatment is performed, and the needle punching density is 150 needles / cm 2 , the carbon fiber direction between the upper and lower two adjacent carbon fiber unidirectional cloths of each carbon fiber tire is at an angle of 90°;

[0072] S2: immerse the carbon fiber preform in a 40wt% concentration of phenolic resin alcohol solution, and after immersion, dry treatment is performed until the alcohol is completely volatilized to obtain an impregnated body;

[0073] S3: carbonize the impregnated body to obtain a carbonized body, the carbonization temperature is 900℃, and the holding time is 6h, and steps S2 and S3 are repeated until the density of the carbonized body reaches 1.4g / cm 3 ;

[0074] S4: perform low-temperature graphitization treatment on the carbonized body in nitrogen to obtain a graphitized blank, and the treatment temperature is 1700℃ and the holding time is 2h;

[0075] S5: uniformly mix silicon carbide powder and phenolic powder to obtain first friction layer pressing powder, the particle size of the silicon carbide in the first friction layer pressing powder is 50 microns, the content of the silicon carbide is 45vol%, and the content of the phenolic powder is 55vol%, the first friction layer pressing powder is uniformly laid on the graphitized blank, and the first blank is obtained by pressing at a temperature of 90℃ for 30min, the pressure is 12MPa, and the thickness after pressing is 0.22mm;

[0076] S6: mixing the silicon carbide powder and the phenolic powder uniformly to obtain a second friction layer pressing powder, the particle size of the silicon carbide in the second friction layer pressing powder is 100 microns, the content of the silicon carbide is 60 vol%, the content of the phenolic powder is 40 vol%, the second friction layer pressing powder is uniformly laid on the first compact, and the second compact is obtained by pressing at a temperature of 150°C for 60 min, the pressing pressure is 14 MPa, and the thickness after pressing is 0.8 mm;

[0077] S7: the second compact is machined to obtain a brake disc compact, and a product having a vent hole and the like is prepared;

[0078] S8: the brake disc compact is placed in a boron nitride crucible and then placed in a high-temperature vacuum furnace for siliconizing treatment, and after the siliconizing treatment is completed, surface grinding and size processing are performed to obtain the carbon ceramic brake disc with a double-layer friction layer, the boron nitride crucible is pre-filled with pure silicon powder with a mass of 1.1 times the mass of the compact, the siliconizing treatment temperature is 1650°C, the holding time is 3h, and the furnace pressure is less than 1000Pa.

[0079] Example 2

[0080] The embodiment provides a carbon ceramic brake disc with a double-layer friction layer, and the preparation steps of the carbon ceramic brake disc with a double-layer friction layer are as follows:

[0081] S1: repeatedly stacking carbon fiber unidirectional cloth and carbon fiber tire to obtain a carbon fiber preform, after each layer of carbon fiber unidirectional cloth and each layer of carbon fiber tire are stacked, needle punching treatment is performed, the needle punching density is 150 needles / cm 2 , and the carbon fiber direction between the upper and lower two carbon fiber unidirectional cloths of each carbon fiber tire is at an angle of 90°;

[0082] S2: immersing the carbon fiber preform in a 40wt% concentration of phenolic resin alcohol solution, and performing drying treatment until the alcohol is completely volatilized to obtain an impregnated body;

[0083] S3: carbonizing the impregnated body to obtain a carbonized body, the carbonization temperature is 900°C, and the holding time is 6h, and steps S2 and S3 are repeated until the density of the carbonized body reaches 1.4g / cm 3 ;

[0084] S4: performing low-temperature graphitization treatment on the carbonized body in nitrogen to obtain a graphitized compact, the treatment temperature is 1700°C, and the holding time is 2h;

[0085] S5: uniformly mixing silicon carbide powder and phenolic powder to obtain first friction layer pressing powder, the particle size of silicon carbide in the first friction layer pressing powder is 50 microns, the content of silicon carbide is 45 vol%, the content of phenolic powder is 55 vol%, uniformly laying the first friction layer pressing powder on the graphitized compact, pressing for 30 min at a temperature of 90°C to obtain a first compact, the pressure is 12 MPa, and the thickness after pressing is 0.33 mm;

[0086] S6: uniformly mixing silicon carbide powder and phenolic powder to obtain second friction layer pressing powder, the particle size of silicon carbide in the second friction layer pressing powder is 100 microns, the content of silicon carbide is 60 vol%, the content of phenolic powder is 40 vol%, uniformly laying the second friction layer pressing powder on the first compact, pressing for 60 min at a temperature of 150°C to completely solidify to obtain a second compact, the pressure is 14 MPa, and the thickness after pressing is 1.0 mm;

[0087] S7: machining the second compact to obtain a brake disc compact, and preparing a product having a ventilation channel and other characteristics;

[0088] S8: placing the brake disc compact into a boron nitride crucible, and then placing the brake disc compact into a high-temperature vacuum furnace for siliconizing treatment, after the siliconizing treatment is completed, performing surface grinding and size processing to obtain the carbon ceramic brake disc with a double-layer friction layer, the boron nitride crucible is pre-filled with pure silicon powder with a mass of 1.1 times the mass of the compact, the siliconizing treatment temperature is 1650°C, the holding time is 3 h, and the furnace pressure is less than 1000 Pa.

[0089] Example 3

[0090] The embodiment provides a carbon ceramic brake disc with a double-layer friction layer, and preparation steps of the carbon ceramic brake disc with a double-layer friction layer are as follows:

[0091] S1: repeatedly stacking carbon fiber unidirectional cloth and carbon fiber tire to obtain a carbon fiber preform, after each layer of carbon fiber unidirectional cloth and each layer of carbon fiber tire are stacked, needle punching treatment is performed, the needle punching density is 150 needles / cm 2 , and the carbon fiber direction between the upper and lower two carbon fiber unidirectional cloths of each carbon fiber tire is at an angle of 90°;

[0092] S2: immersing the carbon fiber preform in a 40 wt% concentration of phenolic resin alcohol solution, and performing drying treatment until the alcohol is completely volatilized to obtain an impregnated body;

[0093] S3: performing carbonization treatment on the impregnated body to obtain a carbonized body, the carbonization temperature is 900°C, and the holding time is 6 h, and steps S2 and S3 are repeatedly performed until the density of the carbonized body reaches 1.4 g / cm 3 ;

[0094] S4: the carbonized body is subjected to low-temperature graphitization treatment in nitrogen to obtain a graphitized body, the treatment temperature is 1700°C, and the holding time is 2h;

[0095] S5: silicon carbide powder and phenolic powder are uniformly mixed to obtain first friction layer pressing powder, the particle size of the silicon carbide in the first friction layer pressing powder is 50 microns, the content of the silicon carbide is 45 vol%, the content of the phenolic powder is 55 vol%, the first friction layer pressing powder is uniformly laid on the graphitized body, and the first body is obtained by pressing at a temperature of 90°C for 30 min, the pressure is 12 MPa, and the thickness after pressing is 0.12 mm;

[0096] S6: silicon carbide powder and phenolic powder are uniformly mixed to obtain second friction layer pressing powder, the particle size of the silicon carbide in the second friction layer pressing powder is 100 microns, the content of the silicon carbide is 60 vol%, the content of the phenolic powder is 40 vol%, the second friction layer pressing powder is uniformly laid on the first body, and the second body is obtained by pressing at a temperature of 150°C for 60 min to completely solidify, the pressure is 14 MPa, and the thickness after pressing is 0.5 mm;

[0097] S7: the second body is subjected to mechanical processing to obtain a brake disc body, and the product is prepared to have a ventilation channel and other characteristics;

[0098] S8: the brake disc body is placed in a boron nitride crucible and then placed in a high-temperature vacuum furnace for siliconizing treatment, after the siliconizing treatment is completed, surface grinding and size processing are performed to obtain the carbon ceramic brake disc with a double-layer friction layer, the boron nitride crucible is pre-filled with pure silicon powder with a mass of 1.1 times the mass of the body, the siliconizing treatment temperature is 1650°C, the holding time is 3h, and the furnace pressure is less than 1000 Pa.

[0099] Example 4

[0100] The embodiment provides a carbon ceramic brake disc with a double-layer friction layer, and the preparation steps of the carbon ceramic brake disc with a double-layer friction layer are as follows:

[0101] S1: carbon fiber unidirectional cloth and carbon fiber tire are repeatedly overlapped to obtain a carbon fiber preform, after each layer of carbon fiber unidirectional cloth and each layer of carbon fiber tire are overlapped, needle punching treatment is performed, the needle punching density is 150 needles / cm 2 , the carbon fiber direction between the upper and lower two carbon fiber unidirectional cloths of each carbon fiber tire is at an angle of 90°;

[0102] S2: the carbon fiber preform is immersed in a 40wt% concentration of phenolic resin alcohol solution, and after immersion, drying treatment is performed until the alcohol is completely volatilized to obtain an impregnated body;

[0103] S3: carbonizing the impregnated body to obtain a carbonized body, the carbonization temperature is 900℃, and the holding time is 6h, and the steps S2 and S3 are repeated until the density of the carbonized body reaches 1.4g / cm 3 ;

[0104] S4: low-temperature graphitizing the carbonized body in nitrogen to obtain a graphitized body, the treatment temperature is 1700℃, and the holding time is 2h;

[0105] S5: uniformly mixing silicon carbide powder and phenolic powder to obtain first friction layer pressing powder, the particle size of the silicon carbide in the first friction layer pressing powder is 50 microns, the content of the silicon carbide is 45vol%, and the content of the phenolic powder is 55vol%, the first friction layer pressing powder is uniformly laid on the graphitized body, and the first body is obtained by pressing at a temperature of 90℃ for 30min, the pressure is 12MPa, and the thickness after pressing is 0.22mm;

[0106] S6: uniformly mixing silicon carbide powder and phenolic powder to obtain second friction layer pressing powder, the particle size of the silicon carbide in the second friction layer pressing powder is 100 microns, the content of the silicon carbide is 65vol%, and the content of the phenolic powder is 35vol%, the second friction layer pressing powder is uniformly laid on the first body, and the second body is obtained by pressing at a temperature of 150℃ for 60min to completely solidify, the pressure is 14MPa, and the thickness after pressing is 0.8mm;

[0107] S7: mechanically processing the second body to obtain a brake disc body, and the product is prepared to have a ventilation channel and other characteristics;

[0108] S8: placing the brake disc body into a boron nitride crucible, and then placing the brake disc body into a high-temperature vacuum furnace to perform silicon infiltration treatment, and after the silicon infiltration treatment is completed, surface grinding and size processing are performed to obtain the carbon ceramic brake disc with a double-layer friction layer, the boron nitride crucible is pre-filled with pure silicon powder with a mass of 1.1 times the mass of the body, the silicon infiltration treatment temperature is 1650℃, the holding time is 3h, and the furnace pressure is less than 1000Pa.

[0109] Comparative Example 1

[0110] The embodiment provides a carbon ceramic brake disc with a double-layer friction layer, and the preparation steps of the carbon ceramic brake disc with a double-layer friction layer are as follows:

[0111] S1: repeatedly stacking carbon fiber unidirectional cloth and carbon fiber net tire to obtain a carbon fiber preform, the needle punching density is 150 needles / cm 2 , and the carbon fiber direction between the upper and lower two carbon fiber unidirectional cloths of each carbon fiber net tire is at an angle of 90°.

[0112] S2: the carbon fiber prepreg is dipped in a 40wt% concentration of phenolic resin alcohol solution, and after dipping, drying treatment is performed until the alcohol is completely volatilized to obtain an impregnated body;

[0113] S3: the impregnated body is subjected to carbonization treatment to obtain a carbonized body, the carbonization temperature is 900°C, and the holding time is 6h, steps S2 and S3 are repeated until the density of the carbonized body reaches 1.4g / cm 3 ;

[0114] S4: the carbonized body is subjected to low-temperature graphitization treatment in nitrogen to obtain a graphitized body, the treatment temperature is 1700°C, and the holding time is 2h;

[0115] S5: silicon carbide powder and phenolic powder are uniformly mixed to obtain first friction layer pressing powder, the particle size of the silicon carbide in the first friction layer pressing powder is 50 microns, the content of the silicon carbide is 45vol%, and the content of the phenolic powder is 55vol%, the first friction layer pressing powder is uniformly laid on the graphitized body, and pressing is performed at a temperature of 90°C for 30min to obtain a first body, the pressure is 12MPa, and the thickness after pressing is 0.22mm;

[0116] S6: silicon carbide powder and phenolic powder are uniformly mixed to obtain second friction layer pressing powder, the particle size of the silicon carbide in the second friction layer pressing powder is 100 microns, the content of the silicon carbide is 60vol%, and the content of the phenolic powder is 40vol%, the second friction layer pressing powder is uniformly laid on the first body, and pressing is performed at a temperature of 150°C for 60min to completely solidify to obtain a second body, the pressure is 14MPa, and the thickness after pressing is 0.44mm;

[0117] S7: the second body is subjected to mechanical processing to obtain a brake disc body, and the product has features such as ventilation channels;

[0118] S8: the brake disc body is placed in a boron nitride crucible and then placed in a high-temperature vacuum furnace for siliconizing treatment, after the siliconizing treatment is completed, surface grinding and size processing are performed to obtain the carbon-ceramic brake disc with a double-layer friction layer, the boron nitride crucible is pre-filled with pure silicon powder with a mass of 1.1 times the mass of the body, the siliconizing treatment temperature is 1650°C, the holding time is 3h, and the furnace pressure is less than 1000Pa.

[0119] Comparative Example 2

[0120] The present embodiment provides a carbon-ceramic brake disc with a double-layer friction layer, and the preparation steps of the carbon-ceramic brake disc with a double-layer friction layer are as follows:

[0121] S1: carbon fiber unidirectional cloth and carbon fiber net tire are repeatedly overlapped to obtain a carbon fiber prepreg, after each layer of carbon fiber unidirectional cloth and each layer of carbon fiber net tire are overlapped, needle punching treatment is performed, and the needle punching density is 150 needles / cm2 , each carbon fiber net tire between the two adjacent carbon fiber unidirectional cloth on the carbon fiber direction 90 ° angle;

[0122] S2: the carbon fiber preform is immersed in a 40wt% concentration of phenolic resin alcohol solution, and after immersion, drying treatment is performed until the alcohol is completely volatilized to obtain an impregnated body;

[0123] S3: the impregnated body is subjected to carbonization treatment to obtain a carbonized body, the carbonization temperature is 900°C, and the holding time is 6h, and steps S2 and S3 are repeated until the density of the carbonized body reaches 1.4g / cm 3 ;

[0124] S4: the carbonized body is subjected to low-temperature graphitization treatment in nitrogen to obtain a graphitized body, the treatment temperature is 1700°C, and the holding time is 2h;

[0125] S5: the silicon carbide powder and the phenolic powder are uniformly mixed to obtain first friction layer pressing powder, the particle size of the silicon carbide in the first friction layer pressing powder is 50 microns, the content of the silicon carbide is 45vol%, and the content of the phenolic powder is 55vol%, the first friction layer pressing powder is uniformly laid on the graphitized body, and the first body is obtained by pressing at a temperature of 90°C for 30min, the pressure is 12MPa, and the thickness after pressing is 0.22mm;

[0126] S6: the silicon carbide powder and the phenolic powder are uniformly mixed to obtain second friction layer pressing powder, the particle size of the silicon carbide in the second friction layer pressing powder is 100 microns, the content of the silicon carbide is 60vol%, and the content of the phenolic powder is 40vol%, the second friction layer pressing powder is uniformly laid on the first body, and the second body is obtained by pressing at a temperature of 150°C for 60min to completely solidify, the pressure is 14MPa, and the thickness after pressing is 5mm;

[0127] S7: the second body is subjected to mechanical processing to obtain a brake disc body, and the product has features such as ventilation channels;

[0128] S8: the brake disc body is placed in a boron nitride crucible and then placed in a high-temperature vacuum furnace for siliconizing treatment, after the siliconizing treatment is completed, surface grinding and size processing are performed to obtain the carbon-ceramic brake disc with a double-layer friction layer, the boron nitride crucible is pre-filled with pure silicon powder with a mass of 1.1 times the mass of the body, the siliconizing treatment temperature is 1650°C, the holding time is 3h, and the furnace pressure is less than 1000Pa.

[0129] The carbon ceramic brake disc with double-layer friction layer prepared in the above-mentioned examples 1-4 and comparative examples 1-2 is tested, and the dynamic friction coefficient and wear rate of the carbon ceramic brake disc sample are tested by using the MM-1000 friction tester, the effective friction surface of the test ring is D75mm / D55mmx10mm, and the specific pressure is 98N / cm 2 , the inertia is 3kgf·cm·s 2 , and the linear speed is 25m / s.

[0130] The test data are shown in Table 1.

[0131] Table 1 Test data of the carbon ceramic brake disc with double-layer friction layer prepared in examples 1-4 and comparative examples 1-2

[0132]

[0133] From the above example and comparative example data, the second friction layer is located at the outermost layer of the brake disc, and the increase of the silicon carbide content in the second friction layer can reduce the wear amount, which indicates that the increase of the silicon carbide content in the friction layer is beneficial to improve the wear resistance of the friction layer. As can be seen from comparative example 1 and example 1, when the thickness of the second friction layer is less than the minimum value of the theoretical friction layer thickness, the performance of the friction layer is greatly reduced, and the friction layer appears peeling phenomenon. And as can be seen from comparative example 2 and example 1, when the thickness of the second friction layer is greater than the theoretical value, the friction layer also causes peeling phenomenon. It is indicated that when the actual thickness of the second friction layer is between the minimum friction layer theoretical value and the maximum friction layer theoretical value, the performance of the friction layer is better and more stable. The thickness of the second friction layer is closely related to the thickness of the first friction layer, and the silicon carbide content and the silicon content of the two layers of friction layer, and flexible setting of the thickness of the second friction layer is more conducive to improving the comprehensive performance of the brake disc.

[0134] The above only discloses several preferred embodiments of the present application, and of course cannot limit the scope of the rights of the present application, so the equivalent changes made in the patent application scope of the present application still belong to the scope covered by the present application.

Claims

1. A carbon-carbide brake disc having a dual layer friction layer, characterised in that, The carbon ceramic brake disc comprises a base layer and a friction layer, the friction layer comprises a first friction layer and a second friction layer, the first friction layer is located between the base layer and the second friction layer; the thickness of the first friction layer is , the content of silicon carbide is , the content of silicon is ; the thickness of the second friction layer is , the content of silicon carbide is , the content of silicon is , and the thickness of the second friction layer satisfies the following formula: Among them, the coefficient β is the thickness coefficient, and the value range is 0.9 or 5. ΔT is the difference between the siliconizing temperature and the room temperature, and ΔT is 1600K; the silicon carbide content in the first friction layer is 50-80 vol%, and the silicon content is 20-50 vol%; the silicon carbide content in the second friction layer is 70-95 vol%, and the silicon content is 5-30 vol%. The first friction layer includes a first coarse silicon carbide with a particle size of 40-80 microns and a first fine silicon carbide with a particle size of 0.5-30 microns, and the second friction layer includes a second coarse silicon carbide with a particle size of 80-150 microns and a second fine silicon carbide with a particle size of 0.5-30 microns.

2. The carbon-carbon brake disc with double-layer friction layer according to claim 1, wherein, The volume ratio of the first coarse silicon carbide to the first fine silicon carbide is 1:1-10:

1.

3. The carbon-carbon brake disc with double-layer friction layer according to claim 1, wherein the friction layer is made of a mixture of the carbon fibers and the ceramic fibers. The volume ratio of the second coarse silicon carbide to the second fine silicon carbide is 1:1-10:

1.

4. A method for manufacturing a carbon-carbon brake disc with a double-layer friction layer, for manufacturing a carbon-carbon brake disc with a double-layer friction layer according to any one of claims 1 to 3, characterized in that, The steps include: S1: repeatedly overlap carbon fiber unidirectional cloth and carbon fiber tire to obtain a carbon fiber preform, each layer of carbon fiber unidirectional cloth and each layer of carbon fiber tire are subjected to needle punching treatment after being overlapped, the needle punching density is 50-200 needles / cm 2 , the carbon fiber direction between the upper and lower two adjacent carbon fiber unidirectional cloths of each carbon fiber tire is a 90° included angle; S2: impregnating the carbon fiber preform into a 40 wt% phenolic resin alcohol solution, and drying the preform until the alcohol is completely volatilized to obtain an impregnated body; S3: Carbonizing the impregnated body to obtain a carbonized body at a carbonization temperature of 900° C. for 6 hours; S4: subjecting the carbonized body to a low-temperature graphitization treatment in nitrogen to obtain a graphitized body, the treatment temperature being 1700° C. and the temperature being kept for 2 hours; S5: mixing silicon carbide powder and phenolic powder to obtain a first friction layer pressed powder, evenly laying the first friction layer pressed powder on the graphitized green body, and pressing at a temperature of 90° C. for 30 minutes at a pressure greater than 10 MPa to obtain a first green body; S6: mixing silicon carbide powder and phenolic powder to obtain a second friction layer pressed powder, evenly laying the second friction layer pressed powder on the first green body, and pressing at a temperature of 150° C. for 60 minutes to completely solidify the green body, with a pressure greater than 10 MPa; S7: machining the second blank to obtain a brake disc blank; S8: The brake disc blank is placed in a boron nitride crucible and then placed in a high-temperature vacuum furnace for siliconizing treatment. After the siliconizing treatment is completed, the surface is polished and the size is processed to obtain the carbon-ceramic brake disc with a double friction layer. Pure silicon powder 1.1 times the mass of the blank is pre-placed in the boron nitride crucible. The siliconizing treatment temperature is 1600-1700°C, the holding time is 2-4h, and the furnace pressure is less than 1000Pa.

5. The method for preparing a carbon-ceramic brake disc with a double friction layer according to claim 4, characterized in that: S2 and S3 steps are performed at least once to bring the density of the carbonized body to 1.25-1.45 g / cm3 3 .

6. The method for preparing a carbon-ceramic brake disc with a double friction layer according to claim 4, characterized in that: The silicon carbide particle size in the pressed powder of the first friction layer is 40-80 microns, the silicon carbide powder content is 35-55 vol%, and the phenolic powder content is 45-65 vol%.

7. The method for preparing a carbon-ceramic brake disc with a double friction layer according to claim 4, characterized in that: The silicon carbide particle size in the pressed powder of the second friction layer is 80-150 microns, the silicon carbide powder content is 45-75 vol%, and the phenolic powder content is 25-55 vol%.

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