Phenolic resin-based composite material suitable for harsh dry friction working condition

Abstract

The invention relates to a phenolic resin-based composite material suitable for harsh dry friction working conditions. The composite material is prepared from the following components in parts by mass: 60-90 parts of phenolic resin, 5-20 parts of reinforced fibers and 5-20 parts of functionalized silicate nano filler. According to the invention, the generation of a polymer-metal friction interface transfer membrane is regulated and controlled by adding the sodium silicate nano functional filler functionalized by the silane coupling agent and the reinforced fibers, so that the polymer composite material shows extremely low friction coefficient and wear rate under harsh dry friction working conditions, and the adaptability of a phenolic aldehyde matrix to the environment is improved. Meanwhile, the preparation process is simple, the cost is low, and batch production is facilitated.

Description

Technical Field

[0001] The invention relates to the field of polymer self-lubricating composite materials, and in particular to a phenolic resin-based composite material suitable for harsh dry friction working conditions. Background Art

[0002] With the rapid development of high-end equipment technology, many motion mechanisms are facing more demanding working conditions, which seriously affects the service life and reliability of materials. Polymer self-lubricating composite materials have the advantages of good self-lubricating properties and chemical stability, and play an important role in the tribological design of high-end motion systems. Therefore, it is of great practical significance to design and prepare polymer composite materials with excellent tribological properties to meet the requirements of harsh working conditions.

[0003] Phenolic resin is a polymer material formed by cross-linking and curing phenols and aldehydes under the catalytic action of acid or alkali. It is widely used in the preparation of friction materials due to its advantages such as high mechanical strength and heat resistance. However, phenolic resin is brittle and prone to breakage when used alone, which limits its application in high-end equipment lubricating materials. Solid lubricants and reinforcing fillers are usually added to the polymer matrix to improve the mechanical and tribological properties of the material.

[0004] Silicate clay mineral nanomaterials are naturally occurring materials with the advantages of low cost, non-toxicity, and large reserves. They are widely used in catalysis, composite materials, coatings, and other fields. In recent years, the application of silicate minerals in tribology has become more and more extensive, mostly used in coatings or lubricant additives. However, there are few systematic reports on the tribological properties of silicate clay mineral-filled polymer materials. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a phenolic resin-based composite material with extremely low friction coefficient and wear rate and suitable for harsh dry friction working conditions.

[0006] To solve the above problems, the present invention discloses a phenolic resin-based composite material suitable for harsh dry friction working conditions, characterized in that the composite material is composed of the following components in parts by mass: 60-90 parts of phenolic resin, 5-20 parts of reinforcing fibers, and 5-20 parts of functionalized silicate nanofillers.

[0007] The phenolic resin is a thermosetting phenolic resin.

[0008] The reinforcing fiber is any one of carbon fiber, aramid fiber and glass fiber.

[0009] The functionalized silicate nanofiller is prepared according to the following method: firstly, the silicate filler is dispersed in deionized water, and sodium hexametaphosphate is added, and concentrated hydrochloric acid is added to adjust the pH value to 2-5 after ultrasonic dispersion at 30-50°C for 30-60min, and the purified silicate nanofiller is obtained after stirring reaction, multiple centrifugation and drying; then, the silane coupling agent is added to the ethanol / water mixed solution, and ultrasonic dispersion is performed to obtain a mixed solution with a concentration of 0.5-3g / mL; finally, the purified silicate nanofiller is added to the mixed solution, heated and stirred to make it fully react, and then centrifuged and dried to obtain the obtained product; the mass ratio of the deionized water, the silicate filler and the sodium hexametaphosphate is 400-500:100-150:1-3; the mass ratio of the silicate filler and the silane coupling agent is 2-5:1-3.

[0010] The silicate filler is any one of halloysite, kaolin, and attapulgite; the silane coupling agent is any one or more of γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, and triaminosilane; and the ethanol / water mixed solution refers to a solution in which anhydrous ethanol and deionized water are uniformly mixed in a volume ratio of 1:1.

[0011] The stirring reaction conditions are as follows: temperature of 50-80° C., speed of 200-300 r / min, and time of 8-12 h.

[0012] The centrifugal conditions are as follows: the speed is 3000-10000 rpm, the time is 5-10 min, washing with deionized water, and centrifugation 3-5 times.

[0013] The heating and stirring conditions are oil bath, temperature of 80-100° C., time of 6-12 h, and rotation speed of 200-300 r / min.

[0014] The drying conditions are a temperature of 60 to 120° C. and a time of 8 to 24 hours.

[0015] The method for preparing a phenolic resin-based composite material suitable for harsh dry friction working conditions as described above is characterized in that: first, the weights are weighed according to the ratio, and then reinforcing fillers and functionalized silicate nanofillers are added to the phenolic resin, and a premix is ​​obtained by mechanical stirring; the premix is ​​plasticized and crushed to obtain a modified phenolic composite material powder, and the modified phenolic composite material powder is cross-linked by electron beam radiation with a radiation agent dosage of 20kGy~100kGy to obtain a cross-linked phenolic composite material; the cross-linked phenolic composite material is placed in a rectangular mold, and transferred to a flat vulcanizer for compression molding to obtain a phenolic composite material plate, and the modified phenolic composite material plate is heat treated.

[0016] The mechanical stirring conditions are a rotation speed of 1000 r / min and a time of 30 to 60 min.

[0017] The plasticizing conditions refer to using a double-roll mill to mix the premix, with the front roll temperature being 80-120° C., the rear roll temperature being 120-140° C., and the plasticizing time being 30-60 min.

[0018] The crushing conditions are that the rotation speed is 500-1500 rpm and the crushing time is 30-60 min.

[0019] The molding conditions are as follows: the temperature of the first stage is 130-160°C, the pressure is 2-5MPa, and the molding time is 10-30min; the temperature of the second stage is 180-200°C, the pressure is 10-20MPa, and the molding time is 45-120min; the temperature of the third stage is 100-120°C, the pressure is 10-20MPa, and the molding time is 1-2h, and finally demolding is performed at room temperature.

[0020] The heat treatment conditions are to use a blast drying oven to increase the temperature from 100-120°C to 230-250°C at a heating rate of 10°C / h, keep the temperature for 12-24h, and then cool to room temperature.

[0021] Compared with the prior art, the present invention has the following advantages: 1. The present invention utilizes a silane coupling agent to perform functionalization treatment on silicate nanofillers, thereby enhancing the interaction between the silicate fillers and the phenolic resin, thereby improving the dispersion of the silicate fillers in the phenolic resin.

[0022] 2. The present invention optimizes the formula by adding modified silicate nanofillers and reinforcing fibers to act as stress concentration points, thereby playing the role of bearing external forces, consuming fracture energy and preventing matrix crack expansion, thereby improving the mechanical properties of the material.

[0023] 3. The present invention uses electron beam radiation cross-linking to treat the phenolic composite material to enhance the cross-linking degree of the phenolic molecular chain itself. At the same time, silicate nanofillers and reinforcing fibers are used as cross-linking points to enhance the binding force with the phenolic molecular chain, thereby achieving the effect of strengthening and toughening.

[0024] 4. The present invention introduces modified silicate nanofillers and reinforcing fibers into phenolic resin, which exhibits extremely low friction coefficient and wear rate under harsh dry friction conditions. The improvement of the tribological performance of the phenolic composite material is due to the formation of a transfer film at the friction interface. Under this condition, the transfer film formed at the friction interface has high load-bearing capacity and self-lubricating properties, avoiding direct contact between the friction pairs and greatly reducing the friction and wear of the material.

[0025] 5. The composite material obtained by the present invention has relatively simple composition and structure, does not need to add other additives, has simple preparation process, low processing cost, strong operability, and is convenient for mass production. DETAILED DESCRIPTION

[0026] A phenolic resin-based composite material suitable for harsh dry friction working conditions. The composite material consists of the following components in parts by mass (g): 60-90 parts of phenolic resin, 5-20 parts of reinforcing fibers, and 5-20 parts of functionalized silicate nanofillers.

[0027] Wherein: the phenolic resin is a thermosetting phenolic resin.

[0028] The reinforcing fiber is any one of carbon fiber, aramid fiber and glass fiber.

[0029] The functionalized silicate nanofiller is prepared according to the following method: first, the silicate filler is dispersed in deionized water, and sodium hexametaphosphate is added, the mass ratio (g / g) of deionized water, silicate filler, and sodium hexametaphosphate is 400~500:100~150:1~3; the silicate filler is any one of halloysite, kaolin, and attapulgite. After ultrasonic dispersion at 30-50°C for 30-60 minutes, concentrated hydrochloric acid is added to adjust the pH value to 2-5, and the reaction is stirred at 50-80°C and 200-300 r / min for 8-12 hours. After multiple centrifugation and drying, a purified silicate nanofiller is obtained; then a silane coupling agent is added to the ethanol / water mixed solution, and the silane coupling agent is any one or more of γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, and triaminosilane; the mass ratio (g / g) of silicate filler and silane coupling agent is 2-5:1-3. The ethanol / water mixed solution refers to a solution in which anhydrous ethanol and deionized water are uniformly mixed at a volume ratio (mL / mL) of 1:1. Ultrasonic dispersion is used to obtain a mixed solution with a concentration of 0.5~3g / mL; finally, the purified silicate nanofiller is added to the mixed solution, heated and stirred to make it fully react, and the heating and stirring conditions are oil bath, temperature of 80~100℃, time of 6~12h, and speed of 200~300r / min. After the reaction, centrifugal drying is obtained. The centrifugal conditions refer to a speed of 3000~10000rpm, a time of 5~10min, washing with deionized water, and centrifugation 3~5 times. The drying conditions refer to a temperature of 60~120℃ and a time of 8~24h.

[0030] A method for preparing a phenolic resin-based composite material suitable for harsh dry friction working conditions: first weigh according to the ratio, then add reinforcing fillers and functionalized silicate nanofillers into the phenolic resin, and mechanically stir at a speed of 1000r / min for 30-60min to obtain a premix; the premix is ​​refined on a double-roll mill, the front roll temperature is 80-120°C, the rear roll temperature is 120-140°C, and the plasticizing time is 30-60min. After plasticizing, the powder is pulverized at a rotation speed of 500-1500 rpm and a pulverizing time of 30-60 minutes to obtain a modified phenolic composite material powder, and the modified phenolic composite material powder is cross-linked by electron beam radiation with a radiation agent dosage of 20 kGy-100 kGy to obtain a cross-linked phenolic composite material; the cross-linked phenolic composite material is placed in a rectangular mold and transferred to a flat vulcanizer for compression molding, and the compression molding conditions are as follows: the temperature in the first stage is 130-160°C, the pressure is 2-5 MPa, and the compression molding time is 10-3 0min, the second stage temperature is 180~200℃, the pressure is 10~20MPa, the molding time is 45~120min, the third stage temperature is 100~120℃, the pressure is 10~20MPa, the molding time is 1~2h, and finally demolding is carried out at room temperature to obtain a phenolic composite material sheet. The modified phenolic composite material sheet is heat treated in a blast drying oven, the temperature is increased from 100~120℃ to 230~250℃ at a heating rate of 10℃ / h, and after keeping warm for 12~24h and cooling to room temperature, the sheet is obtained.

[0031] Example 1 A phenolic resin-based composite material suitable for harsh dry friction working conditions, the contents of the components of the composite material are as follows: 900 g phenolic resin, 50 g reinforcing fiber, and 50 g halloysite functionalized with a silane coupling agent.

[0032] The preparation method comprises the following steps: weighing a total amount of 1 kg according to a proportion, mixing the components and adding them into a high-speed stirrer, premixing them for 30 minutes at a rotation speed of 1000 r / min to obtain a premix; adding the premix into a double-roll mill for plastication, with the front roller temperature at 130°C and the rear roller temperature at 110°C for 45 minutes to obtain a modified phenolic composite material sheet; adding the modified phenolic composite material sheet into a pulverizer, pulverizing them at a rotation speed of 1500 rpm for 30 minutes, and obtaining a modified phenolic composite material powder through plastication and pulverization; and crosslinking the modified phenolic composite material powder through electron beam radiation to obtain The cross-linked phenolic composite material is then placed in a rectangular mold and transferred to a flat vulcanizer for molding, first at a temperature of 140°C, a pressure of 5 MPa, and molding for 30 minutes, then the temperature is increased to 190°C, the pressure is increased to 10 MPa, and molding is performed for 45 minutes, and then the temperature is reduced to 120°C, the pressure is 10 MPa, and molding is performed for 30 minutes to obtain a modified phenolic composite material sheet; the modified phenolic composite material sheet is cooled to room temperature, and after demolding, it is placed in a blast drying oven for heat treatment, the temperature is increased from 120°C to 240°C at a heating rate of 10°C / h, and then cooled to room temperature after keeping warm for 24 hours.

[0033] Example 2 A phenolic resin-based composite material suitable for harsh dry friction working conditions, the contents of the components of the composite material are as follows: 800 g phenolic resin, 100 g reinforcing fiber, and 100 g halloysite functionalized with a silane coupling agent.

[0034] The preparation method is the same as that of Example 1.

[0035] Example 3 A phenolic resin-based composite material suitable for harsh dry friction working conditions, the contents of the components of the composite material are as follows: 750 g phenolic resin, 50 g reinforcing fiber, and 200 g halloysite functionalized with a silane coupling agent.

[0036] The preparation method is the same as that of Example 1.

[0037] Example 4 A phenolic resin-based composite material suitable for harsh dry friction working conditions, the contents of the components of the composite material are as follows: 750 g phenolic resin, 200 g reinforcing fiber, and 50 g halloysite functionalized with a silane coupling agent.

[0038] The preparation method is the same as that of Example 1.

[0039] Example 5 A phenolic resin-based composite material suitable for harsh dry friction working conditions, the contents of the components of the composite material are as follows: 850 g phenolic resin, 100 g reinforcing fiber, and 50 g halloysite functionalized with a silane coupling agent.

[0040] The preparation method is the same as that of Example 1.

[0041] Example 6 A phenolic resin-based composite material suitable for harsh dry friction working conditions, the contents of the components of the composite material are as follows: 800 g phenolic resin, 100 g reinforcing fiber, and 100 g halloysite functionalized with a silane coupling agent.

[0042] The preparation method is the same as that of Example 1.

[0043] Comparative Example 1 A phenolic resin material not subjected to radiation crosslinking treatment 1 kg of phenolic resin is added into a double-roll mill for plastication, with the front roller temperature at 130°C and the rear roller temperature at 110°C for 45 minutes to obtain a phenolic material sheet; the phenolic material sheet is added into a pulverizer and crushed at a speed of 1500rpm for 30 minutes, and phenolic material powder is obtained after plastication and crushing; the phenolic material powder is put into a rectangular mold and transferred to a flat vulcanizer for molding, first at a temperature of 140°C and a pressure of 5MPa for 30 minutes, then the temperature is increased to 190°C and the pressure is increased to 10MPa for 45 minutes, then the temperature is reduced to 120°C and the pressure is 10MPa for 30 minutes to obtain a phenolic material board; the phenolic material board is cooled to room temperature, and after demolding, it is placed in a blast drying oven for heat treatment, the temperature is increased from 120°C to 240°C at a heating rate of 10°C / h, and the temperature is kept for 24 hours before being reduced to room temperature.

[0044] Comparative Example 2 A phenolic resin material cross-linked by electron beam radiation 1 kg of phenolic resin is added to a double-roll mill for plastication, with the front roller temperature at 130°C and the rear roller temperature at 110°C for 45 minutes to obtain a phenolic material sheet; the phenolic material sheet is added to a pulverizer and crushed at a speed of 1500rpm for 30 minutes, and phenolic material powder is obtained after plastication and crushing; the phenolic material powder is cross-linked by electron beam radiation to obtain a cross-linked phenolic material; the cross-linked phenolic material is placed in a rectangular mold and transferred to a flat vulcanizer for molding, first at a temperature of 140°C, a pressure of 5MPa, and molding for 30 minutes, then the temperature is increased to 190°C, the pressure is increased to 10MPa, and molding is carried out for 45 minutes, and then the temperature is reduced to 120°C, the pressure is increased to 10MPa, and molding is carried out for 30 minutes to obtain a phenolic material board; the phenolic material board is cooled to room temperature, and after demolding, it is placed in a blast drying oven for heat treatment, the temperature is increased from 120°C to 240°C at a heating rate of 10°C / h, and the temperature is kept for 24 hours and then reduced to room temperature.

[0045] Comparative Example 3 A phenolic resin-based composite material suitable for harsh dry friction conditions, the contents of the components of the composite material are as follows: 900g phenolic resin, 100g reinforcing fiber.

[0046] The preparation method is the same as that of Example 1.

[0047] Comparative Example 4 A phenolic resin-based composite material suitable for harsh dry friction conditions, the contents of the components of the composite material are as follows: 800g phenolic resin, 200g reinforcing fiber.

[0048] The preparation method is the same as that of Example 1.

[0049] Comparative Example 5 A phenolic resin-based composite material suitable for harsh dry friction working conditions, the contents of the components of the composite material are as follows: 950 g of phenolic resin, and 50 g of halloysite functionalized with a silane coupling agent.

[0050] The preparation method is the same as that of Example 1.

[0051] Comparative Example 6 A phenolic resin-based composite material suitable for harsh dry friction conditions, the contents of the components of the composite material are as follows: 900 g of phenolic resin, and 100 g of halloysite functionalized with a silane coupling agent.

[0052] The preparation method is the same as that of Example 1.

[0053]

Mechanical properties test

[0054] Table 1. Impact strength and flexural strength of materials prepared in Examples and Comparative Examples As can be seen from Table 1, the phenolic composite material obtained by the present invention shows higher impact strength and flexural strength compared with pure phenolic resin without radiation crosslinking treatment. The reason is that the addition of halloysite and reinforcing fiber improves the mechanical strength of phenolic resin, achieving the effect of strengthening and toughening. At the same time, the compatibility of halloysite and phenolic resin after functionalization of silane coupling agent is better, which improves dispersion. When subjected to external force, the load acting on the resin can be effectively transferred to the filler through the interface, which plays a role in bearing external force, consuming fracture energy and preventing matrix crack propagation, increasing the material impact resistance and flexural strength, and showing higher bearing capacity.

[0055]

Tribological performance test

[0056] The tribological test conditions were fixed sliding speed of 1.5 m / s, test load of 2 MPa, duration of 2 h, and dry friction (without lubricating medium).

[0057] The friction coefficient of the material is measured by a torque sensor and the data is recorded online. The wear rate of the material is calculated by the following formula, and the results are shown in Table 2: Ws=∆M / (ρ·F·L)(mm 3 / Nm) Where: ∆M is the mass loss of the material before and after the friction test (g), and the specimens were weighed using a Mettler-Toledo balance (MS105DU, Switzerland). ρ is the density of the material (g / mm 3 ), F is the load applied on the polymer pin (N), and L is the total sliding distance (m).

[0058] The average friction coefficient and wear rate of the obtained materials are shown in Table 2.

[0059] Table 2. Calculation results of average friction coefficient and wear rate of materials prepared in Examples and Comparative Examples As can be seen from Table 2, the phenolic resin composite material with extremely high wear resistance and abrasion resistance suitable for harsh dry friction conditions obtained in the present invention (Examples 1-5) exhibits extremely low friction coefficient and wear rate compared with pure phenolic resin and phenolic resin not treated with electron beam radiation (Comparative Examples 1-2).

[0060] The addition of reinforcing fibers significantly improves the mechanical properties of phenolic resin, has a strengthening and toughening effect, and exhibits an excellent wear-reducing effect. The addition of halloysite with a hollow tubular structure can not only play a load-bearing role, but also effectively reduce the high flash temperature of the reinforcing fibers at the friction interface. At the same time, the friction products of halloysite react with phenolic molecules and steel interfaces under the action of high flash temperature and mechanical stress through friction physical-chemical reactions to generate a transfer film with high load-bearing capacity and easy shearing characteristics, avoiding direct contact between the friction pairs and exhibiting excellent tribological properties.

[0061] The above description is only a specific implementation mode of the present invention and does not constitute a limitation on the scope of protection of this patent. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the scope of protection of the present invention.

Claims

1. A phenolic resin-based composite material suitable for harsh dry friction conditions, characterized in that: The composite material consists of the following components in parts by mass: 60-90 parts of phenolic resin, 5-20 parts of reinforcing fibers, and 5-20 parts of functionalized silicate nanofillers.

2. A phenolic resin-based composite material suitable for harsh dry friction conditions as claimed in claim 1, characterized in that: The phenolic resin is a thermosetting phenolic resin.

3. A phenolic resin-based composite material suitable for harsh dry friction conditions as claimed in claim 1, characterized in that: The reinforcing fiber is any one of carbon fiber, aramid fiber and glass fiber.

4. A phenolic resin-based composite material suitable for harsh dry friction conditions as claimed in claim 1, characterized in that: The functionalized silicate nanofiller is prepared according to the following method: firstly, the silicate filler is dispersed in deionized water, and sodium hexametaphosphate is added, and concentrated hydrochloric acid is added to adjust the pH value to 2-5 after ultrasonic dispersion at 30-50°C for 30-60min, and the purified silicate nanofiller is obtained after stirring reaction, multiple centrifugation and drying; then, the silane coupling agent is added to the ethanol / water mixed solution, and ultrasonic dispersion is performed to obtain a mixed solution with a concentration of 0.5-3g / mL; finally, the purified silicate nanofiller is added to the mixed solution, heated and stirred to make it fully react, and then centrifuged and dried to obtain the obtained product; the mass ratio of the deionized water, the silicate filler and the sodium hexametaphosphate is 400-500:100-150:1-3; the mass ratio of the silicate filler and the silane coupling agent is 2-5:1-3.

5. A phenolic resin-based composite material suitable for harsh dry friction conditions as claimed in claim 4, characterized in that: The silicate filler is any one of halloysite, kaolin, and attapulgite; the silane coupling agent is any one or more of γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, and triaminosilane; and the ethanol / water mixed solution refers to a solution in which anhydrous ethanol and deionized water are uniformly mixed in a volume ratio of 1:

1.

6. A phenolic resin-based composite material suitable for harsh dry friction conditions as claimed in claim 4, characterized in that: The stirring reaction conditions are as follows: temperature of 50-80° C., speed of 200-300 r / min, and time of 8-12 h.

7. A phenolic resin-based composite material suitable for harsh dry friction conditions as claimed in claim 4, characterized in that: The centrifugal conditions are as follows: the speed is 3000-10000 rpm, the time is 5-10 min, washing with deionized water, and centrifugation 3-5 times.

8. A phenolic resin-based composite material suitable for harsh dry friction conditions as claimed in claim 4, characterized in that: The heating and stirring conditions are oil bath, temperature of 80-100° C., time of 6-12 h, and rotation speed of 200-300 r / min.

9. The method for preparing a phenolic resin-based composite material suitable for harsh dry friction conditions according to claim 1, characterized in that: Firstly, the weights are weighed according to the proportion, and then the reinforcing filler and the silicate nanofiller after functional treatment are added to the phenolic resin, and a premix is ​​obtained by mechanical stirring; the premix is ​​plasticized and crushed to obtain a modified phenolic composite material powder, and the modified phenolic composite material powder is cross-linked by electron beam radiation with a radiation agent dosage of 20kGy to 100kGy to obtain a cross-linked phenolic composite material; the cross-linked phenolic composite material is put into a rectangular mold, and transferred to a flat vulcanizer for compression molding to obtain a phenolic composite material plate, and the modified phenolic composite material plate is heat treated to obtain.

10. The method for preparing a phenolic resin-based composite material suitable for harsh dry friction conditions according to claim 9, characterized in that: The mechanical stirring conditions are a rotation speed of 1000 r / min and a time of 30 to 60 min.

11. The method for preparing a phenolic resin-based composite material suitable for harsh dry friction conditions according to claim 9, characterized in that: The plasticizing conditions refer to using a double-roll mill to mix the premix, with the front roll temperature being 80-120° C., the rear roll temperature being 120-140° C., and the plasticizing time being 30-60 min.

12. The method for preparing a phenolic resin-based composite material suitable for harsh dry friction conditions according to claim 9, characterized in that: The crushing conditions are that the rotation speed is 500-1500 rpm and the crushing time is 30-60 min.

13. The method for preparing a phenolic resin-based composite material suitable for harsh dry friction conditions according to claim 9, characterized in that: The molding conditions are as follows: the temperature of the first stage is 130-160°C, the pressure is 2-5MPa, and the molding time is 10-30min; the temperature of the second stage is 180-200°C, the pressure is 10-20MPa, and the molding time is 45-120min; the temperature of the third stage is 100-120°C, the pressure is 10-20MPa, and the molding time is 1-2h, and finally demolding is performed at room temperature.

14. The method for preparing a phenolic resin-based composite material suitable for harsh dry friction conditions according to claim 9, characterized in that: The heat treatment conditions are to use a blast drying oven to increase the temperature from 100-120°C to 230-250°C at a heating rate of 10°C / h, keep the temperature for 12-24h, and then cool to room temperature.

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