阅读说明：本技术 一种碳纤维增强碳化硅刹车盘的制备方法 (Preparation method of carbon fiber reinforced silicon carbide brake disc ) 是由 陈为为 马奔 魏晓霖 杨赟杰 张永福 房家旭 王鲁 于 2021-08-27 设计创作，主要内容包括：本发明涉及一种碳纤维增强碳化硅刹车盘的制备方法,属于刹车制动材料技术领域。先将短切碳纤维进行热处理,然后将混合长度的短切碳纤维与树脂以及添加剂混合均匀后放入模压机中模压,再在氮气或惰性气体保护气氛下进行高温裂解,最后在真空熔渗炉中进行硅熔渗,得到碳纤维增强碳化硅刹车盘。本发明所述方法采用混合长度的短切碳纤维为原料,在固态环境下通过模压、裂解、熔渗制备出刹车盘,方法简单、周期短、原料来源广泛、成本低,而且制备出的碳陶刹车盘有着优异的性能,具有很好的市场应用前景。(The invention relates to a preparation method of a carbon fiber reinforced silicon carbide brake disc, and belongs to the technical field of brake materials. The preparation method comprises the steps of firstly carrying out heat treatment on the short carbon fibers, then uniformly mixing the short carbon fibers with the mixed length with resin and additives, then putting the mixture into a mould press for mould pressing, then carrying out high-temperature cracking under the protection atmosphere of nitrogen or inert gas, and finally carrying out silicon infiltration in a vacuum infiltration furnace to obtain the carbon fiber reinforced silicon carbide brake disc. The method adopts the short carbon fibers with mixed length as the raw materials, prepares the brake disc by mould pressing, cracking and infiltration in a solid environment, has the advantages of simple method, short period, wide raw material source and low cost, and the prepared carbon ceramic brake disc has excellent performance and good market application prospect.)

1. A preparation method of a carbon fiber reinforced silicon carbide brake disc is characterized by comprising the following steps: the method comprises the following steps:

(1) placing the chopped carbon fibers at 600-800 ℃ for heat treatment for 2-4 h;

(2) uniformly mixing the heat-treated short carbon fibers with the mixed length with resin and additives, and then putting the mixture into a die press for die pressing to obtain a blank plate; the chopped carbon fibers with the mixed length comprise three or more chopped carbon fibers with different lengths, the resin is phenolic resin or epoxy resin, the additive is C or SiC, and the mass ratio of the chopped carbon fibers with the mixed length to the resin to the additive is 3:3 (5-8);

(3) putting the blank plate into an atmosphere furnace, and carrying out high-temperature cracking under the protective atmosphere of nitrogen or inert gas to obtain a cracking plate;

(4) and (3) paving silicon powder in the crucible, placing a cushion block, placing the cracking plate on the cushion block, and then putting the crucible filled with the silicon powder, the cushion block and the cracking plate into a vacuum infiltration furnace for infiltration to obtain the carbon fiber reinforced silicon carbide brake disc.

2. The method for preparing a carbon fiber reinforced silicon carbide brake disc according to claim 1, wherein the method comprises the following steps: in the step (2), in the short carbon fibers with mixed lengths, the mass ratio of the short carbon fibers with the minimum length to the short carbon fibers with other lengths is 1: (1. + -. 0.1).

3. The method for preparing a carbon fiber reinforced silicon carbide brake disc according to claim 1 or 2, wherein the method comprises the following steps: in the step (2), 3-5 kinds of chopped carbon fibers with different lengths are selected from the chopped carbon fibers with mixed lengths, and the length difference between the chopped carbon fibers with different lengths is not less than 3 mm.

4. The method for preparing a carbon fiber reinforced silicon carbide brake disc according to claim 1, wherein the method comprises the following steps: in the step (2), the mould pressing pressure is 6MPa to 15MPa, and the pressurizing time is 2h to 5 h.

5. The method for preparing a carbon fiber reinforced silicon carbide brake disc according to claim 1, wherein the method comprises the following steps: in the step (3), the high-temperature cracking temperature is 800-1400 ℃, and the cracking time is 5-12 h.

6. The method for preparing a carbon fiber reinforced silicon carbide brake disc according to claim 1, wherein the method comprises the following steps: in the step (3), the flow rate of the nitrogen or inert gas is 20 SLM-50 SLM.

7. The method for preparing a carbon fiber reinforced silicon carbide brake disc according to claim 1, wherein the method comprises the following steps: in the step (4), the cracking plate is placed on the cushion block, and the distance between the lower end of the cracking plate and the silicon powder is 0.7-2.8 mm.

8. The method for preparing a carbon fiber reinforced silicon carbide brake disc according to claim 1, wherein the method comprises the following steps: in the step (4), the infiltration temperature is 1400-1700 ℃, and the infiltration time is 3-10 h.

9. The method for preparing a carbon fiber reinforced silicon carbide brake disc according to claim 1, wherein the method comprises the following steps: in the step (4), the density of the prepared carbon fiber reinforced silicon carbide brake disc is 2.2g/cm³～2.7g/cm³。

10. The method for preparing a carbon fiber reinforced silicon carbide brake disc according to claim 1, wherein the method comprises the following steps: in the step (2), 3-5 kinds of chopped carbon fibers with different lengths are selected from the chopped carbon fibers with mixed lengths, the length difference value between the chopped carbon fibers with different lengths is not less than 3mm, and the mass ratio of the chopped carbon fibers with the minimum length to the chopped carbon fibers with other lengths is 1: (1 +/-0.1), the mould pressing pressure is 6MPa to 15MPa, and the pressurizing time is 2h to 5 h;

in the step (4), the density of the prepared carbon fiber reinforced silicon carbide brake disc is 2.2g/cm³～2.7g/cm³。

Technical Field

The invention relates to a preparation method of a carbon fiber reinforced silicon carbide brake disc, and belongs to the technical field of brake materials.

Background

The brake disc mainly plays a role in reducing speed or stopping suddenly during the running of the automobile, and is particularly important because the brake disc is concerned with the life safety of people in sudden situations. Because the brake can generate a large impact friction force for a short time and generate a large amount of heat energy, the material of the brake disc is required to have the performances of heat resistance, impact resistance, fatigue resistance, high strength and the like. High-temperature-resistant gray cast iron is mostly adopted as a brake material in the prior art, but with the continuous lightening and high-speed automobile, cast iron and graphite steel with higher density are not suitable for the quality and oxidation problems. C_fthe/SiC composite material can be used as a braking part in aviation and high-end automobile industries due to high hardness, excellent friction performance and capability of greatly reducing the quality of a friction braking material.

The existing preparation method of the carbon-ceramic brake disc is time-consuming and complex in processing and high in processing cost, such as the preparation methods disclosed in the following documents and patents:

the patent publication No. CN110483086A discloses a preparation method of a carbon-ceramic brake disc, which comprises the following specific processes: preparing a carbon fiber preform; carrying out chemical vapor deposition on the prefabricated body to prepare a C/C composite material; processing the C/C composite material into unit modules; preparing a C/C brake disc by bonding; and (5) permeating the reaction melt to prepare the carbon-ceramic brake disc. The fiber preform prepared by the method is a three-dimensional needling structure carbon fiber preform, the used fiber is mainly long fiber, the method has long processing time and high cost due to material waste, and the brake disc is formed by bonding unit modules, so that the bonding part is easy to layer, and the overall mechanical property of the material is low.

"Liuyanping" for treating angiopathy_f/Study of surface residual stress of SiC composite Material [ D]The national defense science and technology university, 2009 "discloses a preparation method of a carbon-ceramic brake disc, which comprises the following steps: first of all byImpregnating the chopped carbon fibers with phenolic resin, drying and forming to obtain carbon fiber reinforced phenolic resin (CFRP), forming a C/C biscuit by the CFRP through a pyrolysis reaction, placing the C/C biscuit in a furnace for vacuum graphitization treatment, and then placing the C/C biscuit in a vacuum hot pressing furnace for silicon infiltration to obtain the carbon fiber reinforced silicon carbide matrix. The process requires impregnation of chopped fibers, and requires mixing of raw materials in a liquid environment, so that the process is time-consuming and complicated, the process cost is high, and the process is not favorable for processing products with complicated shapes.

Patent publication No. CN107266075A discloses a preparation method of a multilayer C/C-SiC composite material with a symmetrical gradient structure. The material is prepared by adopting chopped fibers, fiber plain cloth, phenolic resin and industrial silicon powder as raw materials through processes of mould pressing, cracking carbonization, infiltration and the like. Although the method adopts chopped fibers to reduce the cost and simplifies the processing technology by carrying out die pressing in a solid environment, the brake disc prepared by the method has uneven mechanical properties and is easy to separate and layer when stressed due to the adoption of a multilayer structure and poor combination of layers.

Disclosure of Invention

Based on the defects in the prior art, the invention provides the preparation method of the carbon fiber reinforced silicon carbide brake disc, the method adopts short carbon fibers with mixed lengths as raw materials, and the brake disc is prepared by mould pressing, cracking and infiltration in a solid environment.

The technical scheme adopted by the invention is as follows:

a preparation method of a carbon fiber reinforced silicon carbide brake disc comprises the following steps:

(1) placing the chopped carbon fibers at 600-800 ℃ for heat treatment for 2-4 h;

(2) uniformly mixing the heat-treated short carbon fibers with the mixed length with resin and additives, and then putting the mixture into a die press for die pressing to obtain a blank plate;

the chopped carbon fibers with the mixed length comprise three or more chopped carbon fibers with different lengths, the resin is phenolic resin or epoxy resin, the additive is C or SiC, and the mass ratio of the chopped carbon fibers with the mixed length to the resin to the additive is 3:3 (5-8);

(3) putting the blank plate into an atmosphere furnace, and carrying out high-temperature cracking under the protective atmosphere of nitrogen or inert gas to obtain a cracking plate;

(4) and (3) paving silicon powder in the crucible, placing a cushion block, placing the cracking plate on the cushion block, and then putting the crucible filled with the silicon powder, the cushion block and the cracking plate into a vacuum infiltration furnace for infiltration to obtain the carbon fiber reinforced silicon carbide brake disc.

In the step (2), in the mixed length of chopped carbon fibers, the mass ratio of the chopped carbon fibers with the minimum length to the chopped carbon fibers with other lengths is preferably 1: (1 ± 0.1); among the chopped carbon fibers with mixed length, 3-5 chopped carbon fibers with different lengths are preferably selected, and the length difference between the chopped carbon fibers with different lengths is not less than 3 mm.

In the step (2), the molding pressure is preferably 6MPa to 15MPa, the pressurizing time is preferably 2h to 5h, the porosity and the fiber distribution state of the composite material can be changed by regulating and controlling the molding conditions, and the optimization of the structure and the performance is easy to realize.

In the step (3), the high-temperature cracking temperature is preferably 800-1400 ℃, and the cracking time is preferably 5-12 h.

In the step (3), the flow rate of the nitrogen gas or the inert gas is preferably 20SLM to 50 SLM.

In the step (4), the cracking plate is placed on the cushion block, and the distance between the lower end of the cracking plate and the silicon powder is preferably 0.7-2.8 mm.

In the step (4), the infiltration temperature is preferably 1400-1700 ℃, and the infiltration time is preferably 3-10 h.

In the step (4), the density of the prepared carbon fiber reinforced silicon carbide brake disc is preferably 2.2g/cm³～2.7g/cm³。

The invention has the beneficial effects that:

(1) the short carbon fibers with mixed lengths are adopted, and long carbon fibers, carbon fiber plain cloth and single-length short carbon fibers are abandoned, so that the short carbon fibers with mixed lengths can be fully, densely and uniformly distributed in the carbon ceramic composite material, the structural strength of the brake disc is enhanced from the material angle, the isotropy of the material is ensured due to the random distribution of the short carbon fibers, and the product cost is greatly reduced;

(2) compared with the prior method for drying and shaping impregnated carbon fibers in a liquid environment, the method has the advantages that the mixed material is directly molded and shaped under a solid condition and then is subjected to cracking and siliconizing, so that the processing technology is simplified, and the shape of the brake disc can be better controlled; compared with the existing preparation method for splicing the multilayer structure C/C-SiC composite material, the brake disc is prepared by adopting the integral mould pressing method, the components of the materials at each part are uniform, the performance difference at each part is small, the process is simpler, the mechanical property is more excellent, and the structure is more stable.

(3) The method disclosed by the invention is simple, short in preparation period, low in energy consumption, wide in raw material source and low in cost, and the prepared carbon-ceramic brake disc has excellent performance and good market application prospect.

Drawings

Fig. 1 is an optical microscope view of a brake disc prepared in example 1.

Fig. 2 is a Scanning Electron Microscope (SEM) image of a low power of the brake disc prepared in example 1.

FIG. 3 is a high-power scanning electron microscope photograph of the brake disc prepared in example 1.

Fig. 4 is an X-ray diffraction (XRD) pattern of the brake disc prepared in example 1.

Figure 5 is a graph of the compressive strain stress of the brake disc prepared in example 1.

Fig. 6 is a scanning electron microscope photograph of the brake disc prepared in comparative example 1.

Detailed Description

The invention is further illustrated by the following examples in which the process is conventional unless otherwise specified and the starting materials are commercially available from published sources without further specification.

Example 1

(1) Putting the chopped carbon fibers into a muffle furnace, and carrying out heat treatment for 3h at 600 ℃;

(2) mixing the heat-treated chopped carbon fibers with the mixed lengths of 5mm, 10mm and 15mm (the mass ratio of the three chopped carbon fibers with different lengths is 1:1:1) with phenolic resin and silicon carbide according to the mass ratio of 3:3:5, uniformly mixing, putting into a molding press for molding, wherein the molding pressure is 7MPa, the pressurizing time is 5h, and obtaining a carbon fiber reinforced resin blank plate after molding;

(3) putting the blank plate into an atmosphere furnace, introducing nitrogen with the flow of 37SLM as protective gas into the atmosphere furnace, and carrying out pyrolysis for 9h at 900 ℃ to obtain a pyrolysis plate;

(4) uniformly paving silicon powder in a graphite crucible, placing three cushion blocks (the cushion blocks are made of carbon fiber reinforced silicon carbide) in the graphite crucible, and placing a cracking plate on the cushion blocks to ensure that the distance between the lower end of the cracking plate and the silicon powder is 0.8 mm; then putting the graphite crucible filled with the silicon powder, the cushion block and the cracking plate into a vacuum hot pressing furnace, infiltrating for 7 hours at 1450 ℃, and infiltrating the silicon powder under the vacuum condition through capillary action to obtain the graphite crucible with the density of 2.4g/cm³The carbon fiber reinforced silicon carbide brake disc.

Fig. 1 is an optical microscopic view of the brake disc produced, and it can be seen that there are many bright thin stripe structures on the left and right sides of the observation area, these stripe structures being carbon fibers, and the phase represented by the darker colored area being a silicon carbide phase. The carbon fibers are closely arranged in the silicon carbide phase, and the intervals between the carbon fibers are uniform, so that the brake disc has good infiltration and sintering effects.

FIG. 2 is an SEM image of the prepared brake disc, and it can be seen that the carbon fibers are distributed in local order, are disordered integrally, and are distributed in different directions, so that the isotropy of the material is ensured, and the mechanical properties of the material are unified integrally. Fig. 3 is a partially enlarged SEM image of the prepared brake disc, and it can be seen that the surface of the carbon fiber is smooth, the carbon fiber is tightly bonded with the silicon carbide, there is almost no gap between the two phases, and no loose structure is observed, which indicates that the material is well sintered, has a compact structure, and is helpful for improving mechanical properties.

Fig. 4 is an XRD chart of the prepared brake disc, which shows that the material has two phases of a silicon carbide phase and a silicon phase, diffraction peaks of SiC are shown at 34 °, 36 °, 38 °, 41 °, 60 °, 65 ° and 72 ° of 2 θ, and diffraction peaks of Si are shown at 47 °, 56 °, 69 ° and 76 ° of 2 θ, and no carbon peak is observed, which indicates that siliconizing is sufficient and carbon and silicon are sufficiently reacted to form the silicon carbide phase.

FIG. 5 is a compressive strain stress diagram of the prepared brake disc, and according to the test results, the compressive strength of the prepared brake disc can reach 591.5MPa, which shows that the compressive strength of the material is high.

Example 2

(1) Putting the chopped carbon fibers into a muffle furnace, and carrying out heat treatment for 3h at 700 ℃;

(2) mixing the heat-treated chopped carbon fibers with the mixed lengths of 7mm, 10mm and 13mm (the mass ratio of the three chopped carbon fibers with different lengths is 1:1:1) with phenolic resin and silicon carbide according to the mass ratio of 3:3:5, uniformly mixing, putting into a molding press for molding, wherein the molding pressure is 14MPa, the pressurizing time is 3h, and obtaining a carbon fiber reinforced resin blank plate after molding;

(3) putting the blank plate into an atmosphere furnace, introducing nitrogen with the flow of 27SLM as protective gas into the atmosphere furnace, and carrying out pyrolysis for 8h at 1000 ℃ to obtain a pyrolysis plate;

(4) uniformly paving silicon powder in a graphite crucible, placing three cushion blocks (the cushion blocks are made of carbon fiber reinforced silicon carbide) in the graphite crucible, and placing a cracking plate on the cushion blocks to ensure that the distance between the lower end of the cracking plate and the silicon powder is 1.2 mm; then putting the graphite crucible filled with the silicon powder, the cushion block and the cracking plate into a vacuum hot pressing furnace, infiltrating for 6 hours at 1500 ℃, and infiltrating the silicon powder under the vacuum condition through capillary action to obtain the graphite crucible with the density of 2.6g/cm³The carbon fiber reinforced silicon carbide brake disc.

According to the characterization result of the SEM, the carbon fibers in the prepared brake disc are distributed in a local order, are disordered integrally and are different in distribution direction, so that the isotropy of the material is ensured, and the mechanical properties of the material are unified integrally; and the carbon fiber and the silicon carbide are combined more tightly, a gap is hardly formed between the two phases, and no loose structure is observed, which indicates that the material is better sintered and has a compact structure, and is beneficial to improving the mechanical property.

According to the characterization result of XRD, the prepared brake disc has two phases of a silicon carbide phase and a silicon phase, but a carbon peak is not observed, which indicates that siliconizing is sufficient, and carbon and silicon react sufficiently to generate the silicon carbide phase.

According to the test result of the compressive strain stress, the compressive strength of the prepared brake disc can reach 433.3 MPa.

Example 3

(1) Putting the short carbon fibers into a muffle furnace, and carrying out heat treatment for 3h at 800 ℃;

(2) mixing the heat-treated chopped carbon fibers with the mixed lengths of 2mm, 6mm, 10mm and 14mm (the mass ratio of the four chopped carbon fibers with different lengths is 1:1:1) with phenolic resin and carbon according to the mass ratio of 3:3:5, uniformly mixing, putting into a molding press for molding, wherein the molding pressure is 11MPa, and the pressurizing time is 4h, and obtaining a blank plate of the carbon fiber reinforced resin after molding;

(3) putting the blank plate into an atmosphere furnace, introducing nitrogen with the flow of 22SLM as protective gas into the atmosphere furnace, and carrying out pyrolysis for 7h at 1200 ℃ to obtain a pyrolysis plate;

(4) uniformly paving silicon powder in a graphite crucible, placing three cushion blocks (the cushion blocks are made of carbon fiber reinforced silicon carbide) in the graphite crucible, and placing a cracking plate on the cushion blocks to ensure that the distance between the lower end of the cracking plate and the silicon powder is 2.3 mm; then putting the graphite crucible filled with the silicon powder, the cushion block and the cracking plate into a vacuum hot pressing furnace, infiltrating for 5 hours at 1600 ℃, and infiltrating the silicon powder under the vacuum condition through capillary action to obtain the graphite crucible with the density of 2.5g/cm³The carbon fiber reinforced silicon carbide brake disc.

According to the characterization result of the SEM, the carbon fibers in the prepared brake disc are distributed in a local order, are disordered integrally and are different in distribution direction, so that the isotropy of the material is ensured, and the mechanical properties of the material are unified integrally; and the carbon fiber and the silicon carbide are combined more tightly, a gap is hardly formed between the two phases, and no loose structure is observed, which indicates that the material is better sintered and has a compact structure, and is beneficial to improving the mechanical property.

According to the characterization result of XRD, the prepared brake disc has two phases of a silicon carbide phase and a silicon phase, but a carbon peak is not observed, which indicates that siliconizing is sufficient, and carbon and silicon react sufficiently to generate the silicon carbide phase.

According to the test result of the compressive strain stress, the compressive strength of the prepared brake disc can reach 417.9 MPa.

Comparative example 1

On the basis of example 1, the molding pressure in example 1 was changed from 7MPa to 4MPa, and the other steps and process conditions were not changed, and accordingly, a density of 2.3g/cm was obtained³The carbon fiber reinforced silicon carbide brake disc.

FIG. 6 is an SEM image of a brake disc prepared in this comparative example, and it can be found that the prepared brake disc has more pores and looser fiber distribution compared to example 1, and it is mainly because the porosity and fiber distribution of the composite material are affected by the change of the molding pressure.

According to the test result of the compressive strain stress, the compressive strength of the brake disc prepared by the comparative example is 214.8 MPa.

In summary, the above are only some examples of the present invention, and are not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.