CN110655407A

CN110655407A - Preparation method of silicon carbide ceramic with controllable resistance

Info

Publication number: CN110655407A
Application number: CN201910969950.8A
Authority: CN
Inventors: 茹红强; 孙卫康; 汤志强; 李庆春; 王春华
Original assignee: Shenzhen Dongtao New Material Co Ltd; Shandong Dongda New Materials Research Institute Co Ltd
Current assignee: Shenzhen Dongtao New Material Co Ltd; Shandong Dongda New Materials Research Institute Co Ltd
Priority date: 2019-10-12
Filing date: 2019-10-12
Publication date: 2020-01-07

Abstract

The invention relates to a resistance-controllable silicon carbide ceramic and a preparation method thereof, belonging to the field of conductive ceramic materials. The resistance-controllable silicon carbide ceramic raw material comprises: SiC powder, B₄C powder, titanium source, carbon source and TiB₂The powder comprises (by mass ratio) 40-80: 8-30: 20-70: 15-60: 25-55; the invention also provides a preparation method thereof, which comprises the steps of proportioning, sieving, granulating, compression molding, drying and sintering; the invention directly or indirectly introduces TiB into SiC raw material₂The SiC composite ceramic material has the properties of controllable resistance, oxidation resistance, high hardness, wear resistance, high heat conductivity, low thermal expansion coefficient, creep resistance and the like, and can be used in electronic information wearing products and industrial wastewater electricityThe catalyst has great practical prospect in the fields of catalytic oxidation treatment, fuel cell electrodes, high-speed rail pantograph and the like. The invention has the advantages of simple process, low equipment requirement degree, low production cost and convenient batch production.

Description

Preparation method of silicon carbide ceramic with controllable resistance

Technical Field

The invention belongs to the technical field of conductive ceramic materials, and particularly relates to a silicon carbide ceramic material with controllable resistance and a preparation method thereof.

Background

Silicon carbide (SiC) ceramics have excellent properties such as high strength, high hardness, good thermal conductivity, high temperature oxidation resistance, and chemical corrosion resistance, and have been used in the industrial field. However, as a semiconductor material, SiC ceramics has too high resistivity and is not controllable, and generally has poor conductivity, so that SiC ceramics can only be used for high-temperature structural members, wear-resistant and sealing members, and the electrical properties of SiC ceramics cannot be fully exerted, so that the huge potential market practical value of SiC ceramics cannot be fully exploited.

The invention patent with the granted publication number of CN103613388B provides a method for synthesizing TiB at low temperature₂-TiC ceramic composite material, wherein the ceramic raw material components are as follows: TiB₂TiC and metallic nickel, when sintered at high temperature, the metallic nickel is melted to form a liquid phase, thereby densifying the ceramic and having better mechanical properties. However, because the nickel-based composite material contains metallic nickel, the metal generally has a lower melting point than ceramic, is not wear-resistant, cannot resist high temperature, is easy to oxidize and has low hardness, so that the nickel-based composite material cannot be used as a structural component and cannot serve as functional structure integrated ceramic, and has poor conductivity, limited application and low practical value. And the Spark Plasma Sintering (SPS) is adopted, so that the sintering time is short, but the effective working space of the furnace is very small, the production cost is high, the furnace is only limited to be used for research and research in laboratory, the production is unrealistic, and a longer path is provided for batch and large-scale production of enterprises and factories.

The invention patent with the publication number of CN103396123B provides a preparation method of a large-aperture three-dimensional network SiC ceramic material, wherein the ceramic components are SiC and B₄C, mutually grinding SiC with fine particles during high-temperature sinteringDiffusion to form sintering necks, thereby making SiC and B₄C are combined with each other to achieve the purpose of sintering; removing the solvent in the ceramic slurry by means of low-temperature evaporation and organic solvent extraction freezing to obtain a ceramic blank, and sintering; the porous characteristic of the ceramic is realized by adopting the technologies of pore-forming agent, organic foaming agent and the like, but the general practical conclusion of the industry is as follows: the shape of the hole is unstable, the randomness is very high, and the hole can not be randomly modified by people; in the prepared porous ceramic, some holes are in a closed state, some holes are in an open state, some holes are large in size, some holes are small in size, the distribution state of the holes cannot be known, the holes are generally not uniform, and the holes are randomly dispersed. The catalyst is applied to filtering materials of gas, liquid (such as molten metal) and solid particles and catalyst carriers, and the application field is narrower.

In summary, the existing silicon carbide ceramic material has the following defects: (1) the resistivity is large, and the conductivity is weak; (2) the bending strength, the fracture toughness and the Vickers hardness are low.

Disclosure of Invention

The invention aims to provide a preparation method of silicon carbide ceramic with controllable resistance, aiming at the problems that the resistivity of the existing silicon carbide ceramic is generally higher and can not be regulated, so as to realize the following purposes:

(1) according to the preparation method of the silicon carbide ceramic with the controllable resistance, the resistivity of the silicon carbide composite ceramic is remarkably reduced, and the conductivity is improved;

(2) the preparation method of the silicon carbide ceramic with controllable resistance obviously improves the bending strength, the fracture toughness and the Vickers hardness of the silicon carbide composite ceramic.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a resistance-controllable silicon carbide ceramic, comprising: SiC powder, B₄C powder, titanium source, carbon source and TiB₂And (3) pulverizing.

The following are preferred for the technical solution of the present invention:

the raw materials, SiC powder and B₄C powder, titanium source, carbon source and TiB₂The mass ratio of the powder is (40-80): (8-30): (20-70): 15-60): 25-55.

The invention also provides a preparation method of the resistance-controllable silicon carbide ceramic, which comprises the following steps: proportioning, sieving, granulating, compression molding, drying, sintering and processing.

The ingredients are SiC powder and B₄C powder, titanium source, carbon source and TiB₂The powder, the binding agent and the liquid medium are mixed together to form slurry, and the slurry is ball-milled in a ball-milling tank.

The invention also provides a preparation method of the resistance-controllable silicon carbide ceramic, which comprises the following steps:

(1) preparing materials: mixing SiC powder and B₄C powder, titanium source, carbon source and TiB₂Mixing the powder, the binding agent and a liquid medium into slurry, and performing ball milling in a ball milling tank;

(2) sieving and granulating: carrying out spray granulation on the mixed slurry or manually sieving and granulating after drying in a drying oven at 40-100 ℃;

(3) compression molding: putting the granulated powder into a mold, and performing compression molding to prepare a ceramic green body;

(4) and (3) drying: putting the pressed ceramic green body into a drying oven at 60-300 ℃ for drying;

(5) and (3) sintering: putting the green body into vacuum sintering, and reacting and sintering at 1800-2200 ℃ to obtain SiC-TiB₂A conductive ceramic material;

(6) processing: the sintered conductive silicon carbide ceramic material can be processed into various parts by wire cutting processing, mechanical processing and grinding and polishing.

In the step (1), the average grain size of the SiC powder is 0.4-3 μm, and the purity is more than 98%; b is₄The average granularity of the C powder is 0.4-5 mu m, and the purity is more than 96%; TiB₂The average particle size of the powder is 1-5 μm, and the purity is more than 99%.

In the step (1), the Ti source may be Ti powder or TiCl₄、TiO₂Powder, butyl titanate.

In the step (1), the carbon source may be phenolic resin, soft white sugar, carbon black, or graphene.

In the step (1), the binder may be phenolic resin, PVA, PVB or other organic glue.

In the step (1), the liquid medium may be deionized water or other organic solvents such as acetone and ethanol.

In the step (1), SiC powder and B₄C powder, titanium source, carbon source and TiB₂The mass ratio of the powder is (40-80): (8-30): (20-70): 15-60): 25-55.

In the step (2), the specification of the screen mesh in the sieving granulation is 40-100 meshes.

In the step (3), the pressure for compression molding is 50-250 MPa.

In the step (4) described above, the purpose of this step is to prevent formation of pores due to excessive and vigorous evaporation of water in the green compact at the initial stage of sintering in the step (5), which is detrimental to densification of the substrate.

In the step (6), the reaction sintering is carried out at the temperature of 1400 ℃ and 1800 ℃ for 30-120 min; when the sintering temperature is reached, the temperature is kept for 30-240 min.

The invention relates to a preparation method of resistance-controllable silicon carbide ceramic, which comprises the steps of ball-milling raw materials and absolute ethyl alcohol into uniform slurry, drying, grinding, crushing, sieving, granulating, then carrying out compression molding by a press machine, and finally carrying out high-temperature vacuum reaction sintering to obtain the silicon carbide/titanium diboride composite conductive ceramic which has excellent conductivity, adjustable resistivity, high chemical stability, high-temperature oxidation resistance, wear resistance and excellent comprehensive mechanical properties.

Compared with the prior art, the invention has the advantages that:

(1) the invention relates to a preparation method of resistance-controllable silicon carbide ceramic, which comprises the following steps of raw materials of a titanium source and B₄C powder and carbon source react in situ in the silicon carbide ceramic matrix to generate TiB through reaction sintering₂(resistivity is about 1.4X 10^-7Ω · m, resistivity close to that of metallic aluminum), and TiB in the raw material₂The resistivity of the obtained silicon carbide composite ceramic with controllable resistance is 1.7 multiplied by 10^-3-7.6×10^-3Ω·m；

(2) The invention relates to a preparation method of silicon carbide ceramic with controllable resistance, namely TiB₂The introduction of the second phase plays a role in strengthening particles, and can obviously improve the bending strength, the fracture toughness and the Vickers hardness of the silicon carbide composite ceramic; the obtained resistance-controllable silicon carbide ceramic has the bending strength of 342-418MPa and the fracture toughness of 3.57-5.73 MPa.m^1/2The Vickers hardness is 23.52-28.92 GPa;

(3) the invention relates to a preparation method of a resistance-controllable silicon carbide ceramic, which comprises the following raw materials of SiC and TiB₂And B₄C powder, titanium source and carbon source, and B is prepared by sintering at high temperature₄C powder, a titanium source and a carbon source are reacted, for example: b is₄C+TiO₂+C→TiB₂CO and CO gas are discharged to obtain the densified ceramic, the relative density is 90.12-96.34%, the porosity is low and is generally lower than 6%;

(4) according to the preparation method of the resistance-controllable silicon carbide ceramic, the reaction sintering process is adopted, so that a product with adjustable resistivity and plastic shape can be prepared, the process is simple, the requirement on equipment is low, large-scale automatic production is facilitated, the product cost is low, the performance is high, and the market practical value is huge;

(5) according to the preparation method of the silicon carbide ceramic with controllable resistance, the TiB with excellent conductivity is introduced into the silicon carbide ceramic₂The components enable the ceramic to have the high-performance function of integrating the metal electrical property and the ceramic structural property, and have the advantages of adjustable resistivity, high chemical stability, high-temperature oxidation resistance, wear resistance and excellent comprehensive mechanical property, thereby expanding the practical application value of the silicon carbide ceramic; the conductive ceramic can be applied to the anode material of industrial wastewater treatment equipment to improve the electrocatalytic oxidation efficiency, electronic product components, fuel cell electrode materials, high-speed rail pantograph and the like.

Drawings

FIG. 1 shows SiC-TiB prepared in an example of the present invention₂An X-ray diffraction pattern of the conductive ceramic material;

in the figure: (a) is SiC-TiB of example 1₂An X-ray diffraction pattern of the conductive ceramic material,

(b) is SiC-TiB of example 2₂An X-ray diffraction pattern of the conductive ceramic material,

(c) is SiC-TiB of example 3₂An X-ray diffraction pattern of the conductive ceramic material,

(d) is SiC-TiB of example 4₂X-ray diffraction pattern of the conductive ceramic material.

FIG. 2 shows SiC-TiB of example 1 of the present invention₂Scanning electron micrograph of the conductive ceramic material;

(a) is a microscopic structure back scattering picture of the material,

(b) is a secondary electronic picture of the fracture morphology of the material.

FIG. 3 shows SiC-TiB of example 2 of the present invention₂Scanning electron micrograph of the conductive ceramic material;

(a) is a microscopic structure back scattering picture of the material,

FIG. 4 shows SiC-TiB of example 3 of the present invention₂Scanning electron micrograph of the conductive ceramic material;

(a) is a microscopic structure back scattering picture of the material,

FIG. 5 shows SiC-TiB of example 4 of the present invention₂Scanning electron micrograph of the conductive ceramic material;

(a) is a microscopic structure back scattering picture of the material,

FIG. 6 shows SiC-TiB of example 4 of the present invention₂A transmission electron microscope photograph of the conductive ceramic material;

(a) is material matrix intra-crystal and inter-crystal TiB₂A picture of the bright field image of the particle,

(b) is a material matrix SiC and TiB₂Interface high resolution pictures.

Detailed Description

The present invention will be further described with reference to the following specific examples. It should be understood that the following examples are illustrative only and are not intended to limit the scope of the present invention.

Example 1 resistance-controllable silicon carbide ceramic and preparation method thereof

A preparation method of silicon carbide ceramic with controllable resistance comprises the following steps:

(1) mixing SiC powder and B according to the mass ratio₄C powder, titanium powder, carbon black and TiB₂Mixing the powder =80:8:20:15:25, mixing the powder with a PVA solvent with the mass concentration of 3.0% to form slurry, and performing ball milling for 12 hours in a ball milling tank;

the 3.0% PVA solvent is a solution prepared from a PVA binding agent and deionized water, and the mass fraction of the PVA binding agent in the solution is 3.0%;

the SiC powder and B₄C powder, titanium powder, carbon black and TiB₂The mass ratio of the total mass of the powder to the total mass of the 3.0% PVA solvent is 80: 100, respectively;

(2) carrying out spray granulation on the ball-milled slurry;

(3) putting the granulated powder into a mold, and performing compression molding by a press machine under the pressure of 50MPa to obtain a green body;

(4) putting the pressed ceramic green body into a drying oven at 200 ℃ for drying and discharging the water in the body;

(5) placing the green body into vacuum sintering, keeping the temperature at 1400 ℃ for 120min, keeping the temperature at 1800 ℃ for 180min to obtain SiC-TiB₂A conductive ceramic material;

(6) the sintered conductive silicon carbide ceramic material can be processed into various parts by wire cutting processing, mechanical processing and grinding and polishing.

SiC-TiB prepared in this example₂The X-ray diffraction pattern of the conductive ceramic material is shown in figure 1(a), and the scanning electron micrograph of the microstructure and fracture morphology is shown in figure 2.

The SiC-TiB is tested₂The conductive ceramic material has a bending strength of 342MPa and a fracture toughness of 3.57 MPa-m¹ ^/2A Vickers hardness of 23.52GPa, a relative density of 90.12%, a porosity of 5.6%, and a specific resistanceIs 4.5 multiplied by 10^-3Ω·m。

Embodiment 2 resistance-controllable silicon carbide ceramic and preparation method thereof

(1) mixing SiC powder and B according to the mass ratio₄C powder and TiCl₄Soft white sugar, TiB₂Mixing the powder =65:13:35:32:35, mixing the powder with a PVB binder-ethanol solution with the concentration of 5.0% according to the proportion of 100:100 to form slurry, and performing ball milling for 15 hours in a ball milling tank;

(2) drying the ball-milled slurry in a drying oven at 60 ℃, manually grinding and crushing the powder, and sieving the powder by a 60-mesh sieve for granulation;

(3) putting the granulated powder into a mold, and performing compression molding by a press machine under the pressure of 100MPa to obtain a green body;

(4) putting the pressed ceramic green body into a drying oven at 120 ℃ for drying and discharging the water in the body;

(5) putting the green body into vacuum sintering, keeping the temperature at 1550 ℃ for 90min, keeping the temperature for 150min when the sintering temperature reaches 1950 ℃, and obtaining SiC-TiB₂A conductive ceramic material;

SiC-TiB prepared in this example₂The X-ray diffraction pattern of the conductive ceramic material is shown in figure 1(b), and the scanning electron micrograph of the microstructure and fracture morphology is shown in figure 3.

The SiC-TiB is tested₂The conductive ceramic material has a bending strength of 389MPa and a fracture toughness of 4.36 MPa-m¹ ^/2The Vickers hardness was 25.62GPa, the relative density was 92.34%, the porosity was 4.1%, and the resistivity was 1.7X 10^-3Ω·m。

Embodiment 3 silicon carbide ceramic with controllable resistance and preparation method thereof

(1) mixing SiC powder and B according to the mass ratio₄C powder, Ti powder, graphene and TiB₂Mixing the powder =55:20:50:45:42, mixing the mixture with a phenolic resin binder with the concentration of 2.5% and acetone as a medium to form slurry (the mixture can be changed into the slurry mixed with a phenolic resin binder-acetone solution with the concentration of 2.5% according to the proportion of 100: 120), and carrying out ball milling for 12 hours in a ball milling tank;

(2) drying the ball-milled slurry in a drying oven at 80 ℃, manually grinding and crushing the powder, and sieving the powder by a 100-mesh sieve for granulation;

(3) putting the granulated powder into a mold, and performing compression molding by a press machine under the pressure of 200MPa to obtain a green body;

(4) putting the pressed ceramic green body into a drying oven at 250 ℃ for drying and discharging the water in the body;

(5) placing the green body into vacuum sintering, keeping the temperature at 1650 ℃ for 60min, keeping the temperature for 90min when the sintering temperature reaches 2100 ℃, and obtaining SiC-TiB₂A conductive ceramic material;

SiC-TiB prepared in this example₂The X-ray diffraction pattern of the conductive ceramic material is shown in figure 1(c), and the scanning electron micrograph of the microstructure and fracture morphology is shown in figure 4.

The SiC-TiB is tested₂The conductive ceramic material has a bending strength of 418MPa and a fracture toughness of 5.73 MPa-m¹ ^/2The Vickers hardness was 28.92GPa, the relative density was 96.34%, the porosity was 0.8%, and the resistivity was 3.4X 10^-4Ω·m。

Embodiment 4 silicon carbide ceramic with controllable resistance and preparation method thereof

(1) mixing SiC powder and B according to the mass ratio₄C powder, butyl titanate, carbon black and TiB₂Mixing the powder =42:25:65:50:52, mixing the mixture with a phenolic resin bonding agent-ethanol solution with the concentration of 4.5% according to the proportion of 100:150 to form slurry, and performing ball milling for 18 hours in a ball milling tank;

(2) carrying out spray granulation on the ball-milled slurry;

(4) putting the pressed ceramic green body into a drying oven at 100 ℃ for drying and discharging the water in the body;

(5) putting the green body into vacuum sintering, keeping the temperature at 1600 ℃ for 30min, keeping the temperature for 180min when the sintering temperature reaches 2150 ℃ to obtain SiC-TiB₂A conductive ceramic material;

SiC-TiB prepared in this example₂The X-ray diffraction pattern of the conductive ceramic material is shown in figure 1(d), and the scanning electron micrograph of the microstructure and fracture morphology is shown in figure 5.

The SiC-TiB is tested₂The conductive ceramic material has a bending strength of 395MPa and a fracture toughness of 5.10 MPa-m¹ ^/2The Vickers hardness was 26.57GPa, the relative density was 95.15%, the porosity was 2.1%, and the resistivity was 7.6X 10^-4Ω·m。

The above description is only an embodiment of the present invention, and is not intended to limit the scope of the present invention, and various changes may be made in the above embodiment of the present invention. All simple and equivalent changes and modifications made according to the claims and the content of the specification of the present application fall within the scope of the claims of the present patent application. The invention has not been described in detail in order to avoid obscuring the invention.

Claims

1. A silicon carbide ceramic with controllable resistance is characterized in that,

the resistance-controllable silicon carbide ceramic comprises the following raw materials: SiC powder, B₄C powder, titanium source, carbon source and TiB₂And (3) pulverizing.

2. The silicon carbide ceramic with controllable resistance according to claim 1,

the raw materials, SiC powder and B₄C powder, titanium source, carbon source and TiB₂The weight ratio of the powder is (40-80): (8-30): (20-70):(15-60):(25-55)。

3. A preparation method of silicon carbide ceramic with controllable resistance is characterized in that,

the method comprises the following steps: proportioning, sieving, granulating, compression molding, drying and sintering.

4. The method of claim 3, wherein the silicon carbide ceramic having a controllable electrical resistance,

5. The method of claim 3, wherein the silicon carbide ceramic having a controllable electrical resistance,

in the ingredients, the average grain size of SiC powder is 0.4-3 μm, and the purity is more than 98%; b is₄The average granularity of the C powder is 0.4-5 mu m, and the purity is more than 96%; TiB₂The average particle size of the powder is 1-5 μm, and the purity is more than 99%.

6. The method of claim 3, wherein the silicon carbide ceramic having a controllable electrical resistance,

in the compression molding, the compression molding pressure is 50-250 MPa.

7. The method of claim 3, wherein the silicon carbide ceramic having a controllable electrical resistance,

in the mixture, Ti source is Ti powder and TiCl₄、TiO₂One or the combination of any more of powder and butyl titanate.

8. The method of claim 3, wherein the silicon carbide ceramic having a controllable electrical resistance,

in the ingredients, the carbon source is one or a combination of any one of phenolic resin, soft white sugar, carbon black and graphene.

9. The method as claimed in claim 3, wherein the obtained silicon carbide ceramic has a flexural strength of 342-418MPa and a fracture toughness of 3.57-5.73 MPa-m^1/2The Vickers hardness of 23.52-28.92GPa, the porosity of 0.8-5.6% and the resistivity of 1.7X 10^-3-7.6×10^-3Ω·m。