CN109650891B

CN109650891B - Carbon-based through carbon-ceramic composite material and preparation method thereof

Info

Publication number: CN109650891B
Application number: CN201910049133.0A
Authority: CN
Inventors: 侯玉杰; 程诺
Original assignee: Chengdu Zhongchao Carbon Technology Co ltd
Current assignee: Chengdu Zhongchao Carbon Technology Co ltd
Priority date: 2019-01-18
Filing date: 2019-01-18
Publication date: 2022-05-24
Anticipated expiration: 2039-01-18
Also published as: CN109650891A

Abstract

The invention discloses a carbon-based through carbon-ceramic composite material, which is formed by mixing and sintering green coke and ceramic; the ceramic is distributed in carbon bridge pores in the carbon-based material to form the carbon-ceramic composite material with a network penetrating structure. The preparation method comprises the following steps: s1, mixing the carbon material powder and the ceramic powder and then molding to prepare a columnar material; s2, placing the columnar material in a vacuum furnace, heating to 650-750 ℃, sintering at constant temperature for 2h, then heating to 2100 ℃, sintering at constant temperature for 4h, and naturally cooling to obtain the carbon-based through carbon ceramic composite material. The carbon-ceramic composite material disclosed by the invention has the characteristics of a ceramic material besides the characteristics of a carbon material, and has the advantages of high mechanical strength, self-lubricating property, corrosion resistance, good high-temperature resistance, good wear resistance and long service life of a product, and the processing period of the product can be shortened by preparing materials at the early stage, so that the mass production is realized.

Description

Carbon-based through carbon-ceramic composite material and preparation method thereof

Technical Field

The invention relates to the technical field of novel composite materials, in particular to a carbon-based through type carbon-ceramic composite material and a preparation method thereof.

Background

The carbon-graphite material is widely applied to industries such as petroleum, chemical engineering, machinery, metallurgy, aviation, aerospace, nuclear power and the like due to the characteristics of good self-lubricity, chemical stability, high temperature resistance and the like, but the carbon-graphite material is a brittle material, and the inherent strength of the carbon-graphite material is not high, so that the application range is limited, and the carbon-graphite material is usually enhanced by compounding with ceramics and the like in order to improve the mechanical strength.

At present, the traditional carbon-ceramic composite process mainly comprises the following steps: vapor phase reaction and vapor deposition. The carbon graphite parts which are specially treated and completely processed are generally subjected to gas phase reaction or gas phase deposition to generate a layer of carbon ceramic composite material on the surface, and the surface layer still contains 10-15% of unreacted graphite. Therefore, the product has extremely high surface hardness, good self-lubricating property and outstanding corrosion resistance.

However, because the carbon-ceramic composite layer generated on the surface of the carbon graphite is thin, the internal structure of the composite material is not changed, and the porosity of the composite carbon material is generally over 10% due to the process requirements, the surface composite process cannot effectively reduce the internal porosity of the material, so that the mechanical strength of the material cannot be fundamentally improved, even after the carbon-ceramic composite layer is used for a period of time and is worn, the surface hardness and the oxidation resistance of the product are invalid, the service cycle of the product is short, the material cannot be prepared in advance, the processing period is long, the environmental pollution in the production process is serious, and the production cost is high.

Disclosure of Invention

The invention aims to provide a novel carbon-based through carbon ceramic composite material and a preparation method thereof.

The invention provides a carbon-based through carbon-ceramic composite material, which is a carbon-ceramic composite material with a network through structure formed by distributing ceramic materials in carbon bridge pores inside a carbon-based material. The composite material is prepared by mixing and sintering green coke and ceramic. The content of silicon dioxide in the ceramic material is more than 95 percent. The mass percentage of the ceramic in the composite material is 5-15%.

The preparation method of the carbon-based through carbon-ceramic composite material is mainly characterized in that raw coke and ceramic are mixed and formed and then placed in a vacuum furnace for sintering. The method specifically comprises the following steps:

s1, mixing the carbon material powder and the ceramic powder, and preparing the mixture into a columnar material by a cold isostatic pressing method; wherein the carbon material is green coke with the granularity of 1000-1200 meshes, the ceramic is a single-component silicon dioxide material with the granularity of 600-800 meshes, and the content of the ceramic is 5-15%.

S2, placing the columnar material in a vacuum furnace, heating to 650-750 ℃, sintering at constant temperature for 2h, then heating to 2100 ℃, sintering at constant temperature for 4h, and naturally cooling to obtain the carbon-based through carbon ceramic composite material.

Preferably, in the step S2, the carbon-based through carbon ceramic composite material is obtained by sintering at a constant temperature within the range of 650-.

Further preferably, in the step S2, sintering at a constant temperature of 700 ℃ for 2 hours, sintering at a constant temperature of 950 ℃ for 3 hours, sintering at a constant temperature of 1700 ℃ for 4 hours, sintering at a constant temperature of 2100 ℃ for 4 hours, and cooling to obtain the carbon-based through carbon-ceramic composite material.

The inner temperature and the outer temperature of the columnar material are consistent through constant temperature for a certain time. Keeping the temperature at 700 ℃ for 2h to open internal pores of the material; keeping the temperature at 950 ℃ for 3 hours to fully soften the internal ceramic; the temperature is kept at 1700 ℃ for 4h to carbonize and shrink the binder, so that carbon atoms are arranged newly and the ceramic in the binder flows fully; the final performance of the material can be ensured only by sintering at 2100 ℃ for 4h, the binder in the material is completely carbonized and shrunk, carbon atoms are newly arranged, and the ceramic in the material can fully flow.

Compared with the prior art, the invention has the following beneficial effects:

(1) the composite material of the carbon and ceramic through structure is characterized in that the characteristics of volume expansion and contraction of the carbon material and the characteristics of softening and gradual flowability of ceramic powder in the material are utilized in the carbon bridge forming stage in the carbon substrate sintering and heating process, the softened ceramic is extruded to generate plastic deformation in a specific temperature section by utilizing the contraction characteristic of the carbon bridge forming process of the carbon material, and flows and penetrates in the carbon bridge along with the temperature rise, so that the carbon and ceramic through structure is formed, the interior of the material is in a network through structure, and the composite material has the characteristics of a ceramic material besides the characteristics of the carbon material. When the temperature is raised to 400-700 ℃, the matrix material (green coke) of the carbon sequentially undergoes the processes of expansion-carbonization-contraction due to the self-contained binder (such as a substance obtained by coking petroleum), the ceramic starts to soften at 600 ℃, the ceramic has certain fluidity at 700 ℃, at the moment, the carbon matrix just contracts, and the ceramic forms a complete network penetrating structure in the carbon matrix through contraction and extrusion, so that the carbon-ceramic composite material is formed, wherein the composition of the inner material and the outer material of the composite material is consistent. In the traditional process, only a layer of carbon-ceramic composite material is generated on the surface of the carbon graphite, the internal material is not changed, and the porosity of the body material is high and the mechanical strength is not high due to the process requirement.

(2) Because the ceramic forms a penetrating structure in the carbon bridge network inside the carbon base, the composite material has small porosity, high mechanical strength, self-lubricating property, corrosion resistance and good high-temperature resistance, and because all the internal networks penetrate, the wear resistance is good, the service cycle of the product is long, the processing cycle of the product can be shortened by preparing materials in the early stage, and the batch production can be realized.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a temperature rise graph of sintering of a through type carbon-ceramic composite material.

Fig. 2 is a metallographic photograph of the carbon ceramic composite material.

FIG. 3 is an electron microscope photograph of the carbon ceramic composite material.

Detailed Description

The present invention is described in further detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.

It will be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.

A preparation method of a carbon-based through carbon-ceramic composite material specifically comprises the following steps:

s1, uniformly mixing the raw coke with the granularity of 1000-1200 meshes and the silicon dioxide with the granularity of 600-800 meshes, wherein the ceramic content is 5-15%, and then preparing the columnar material by adopting a cold isostatic pressing method.

And S2, placing the columnar material in a vacuum furnace, heating to 700 ℃, sintering at a constant temperature for 2h, heating to 950 ℃, sintering at a constant temperature for 3h, heating to 1700 ℃, sintering at a constant temperature for 4h, heating to 2100 ℃, sintering at a constant temperature for 4h, and naturally cooling to obtain the carbon-based penetrating carbon-ceramic composite material. The specific temperature rise curve is shown in fig. 1.

FIG. 2 is a metallographic photograph of the composite material prepared in this example at 200 times magnification, from which it can be seen that the composite material had a uniform texture, no fraction of the particle size, and no boundary line.

Fig. 3 is an electron micrograph of the composite material prepared in this example at 8000 times magnification, and it can be seen from the figure that the ceramic material in the composite material is uniformly distributed, and a full network-through carbon bridge structure has been formed.

The performance ratio of the through-type carbon ceramic composite material prepared in the example to the carbon ceramic composite material prepared by the conventional process is shown in table 1. As can be seen, the novel carbon-ceramic composite material provided by the invention has obviously better properties such as hardness, strength, volume density, porosity, thermal expansion coefficient and the like than the carbon-ceramic composite material prepared by the traditional process.

TABLE 1 Performance testing of run-through carbon-ceramic composites versus conventional carbon-ceramic composites

Sample Properties

Shore hardness

Bulk density

Flexural strength

Compressive strength

Porosity of the alloy

Coefficient of thermal expansion

Penetrating type carbon-ceramic composite material

HS110

1.95g/cm³

100Mpa

300Mpa

1

5.5

Traditional carbon-ceramic composite material

HS100

1.79g/cm³

65Mpa

150Mpa

2

4

In conclusion, the penetrating type carbon-ceramic composite material provided by the invention has the advantages that due to the network penetrating structure of the ceramic in the carbon base, the material is high in mechanical strength, self-lubricating property, corrosion resistance and high-temperature resistance, due to the fact that all networks in the material penetrate through the material, the wear resistance is good, the service cycle of the product is long, the processing cycle of the product can be shortened by preparing the material in the early stage, and batch production is realized.

While embodiments of the invention have been disclosed above, it is not intended to be limited to the uses set forth in the specification and examples. It can be applied to all kinds of fields suitable for the present invention. Additional modifications will readily occur to those skilled in the art. It is therefore intended that the invention not be limited to the exact details and illustrations described and illustrated herein, but fall within the scope of the appended claims and equivalents thereof.

Claims

1. A carbon-based through carbon-ceramic composite material is characterized in that a ceramic material is distributed in carbon bridge pores in the carbon-based material to form the carbon-ceramic composite material with a network through structure;

the composite material is formed by mixing and sintering green coke and ceramic powder; the preparation method comprises the following steps:

s1, uniformly mixing the carbon material powder and the ceramic powder, and molding the mixture by using an isostatic press to prepare a columnar material;

the carbon material is green coke;

the ceramic powder is silicon dioxide;

s2, placing the columnar material in a vacuum furnace, heating to 650-750 ℃, sintering at constant temperature for 2h, then heating to 2100 ℃, sintering at constant temperature for 4h, and naturally cooling to obtain the carbon-based through carbon-ceramic composite material.

2. The carbon-based through carbon-ceramic composite material according to claim 1, wherein the ceramic powder has a silica content of 95% or more.

3. The carbon-based through carbon-ceramic composite material as claimed in claim 2, wherein the mass percentage of the ceramic powder in the composite material is 5-15%.

4. A preparation method of the carbon-based through carbon-ceramic composite material as claimed in any one of claims 1 to 3, characterized in that the carbon-based through carbon-ceramic composite material is prepared by mixing raw coke and ceramic powder, molding, and sintering in a vacuum furnace;

the method comprises the following steps:

the carbon material is green coke;

the ceramic powder is silicon dioxide;

5. The method for preparing the carbon-based through carbon-ceramic composite material as claimed in claim 4, wherein in the step S1, the carbon material is green coke with a particle size of 1000-1200 meshes, the ceramic powder with a particle size of 600-800 meshes, and the content of the ceramic powder is 5-15%.

6. The method for preparing a carbon-based through-type carbon-ceramic composite material according to claim 5, wherein the step S1 is performed by a cold isostatic pressing method to form a columnar material.

7. The method as claimed in claim 4, wherein in step S2, the carbon-based through-type carbon-ceramic composite material is obtained by sintering at constant temperature within the range of 650-750 ℃ for 2h, 900-1000 ℃ for 3h, 1600-1700 ℃ for 4h, and 2100-4 h, and cooling.

8. The method for preparing the carbon-based through carbon-ceramic composite material according to claim 7, wherein in the step S2, the carbon-based through carbon-ceramic composite material is obtained by sintering the mixture at a constant temperature of 700 ℃ for 2 hours, at a constant temperature of 950 ℃ for 3 hours, at a constant temperature of 1700 ℃ for 4 hours, and at a constant temperature of 2100 ℃ for 4 hours in sequence and cooling the mixture.