Low specific surface area TiB2-TiC composite ceramic material and preparation method thereof

Abstract

The application provides a low specific surface area TiB2-TiC composite ceramic material and a preparation method thereof, and belongs to the technical field of ceramic materials. A boron source, a titanium source and a carbon source are dispersed in a high polymer grid formed by a high polymer grid agent under the action of an initiator to obtain a high polymer grid gel precursor with uniformly mixed titanium, boron and carbon elements. The high polymer grid gel precursor ensures uniform mixing of reaction raw materials, and microscopically uniformly mixed TiB2-TiC powder is obtained in a sintering process. In the sintering process of the gel precursor, the carbon elements in the grid reduce the specific surface area of the products TiB2 and TiC in the sintering process, so that the TiB2-TiC composite ceramic material with uniform mixing and low specific surface area is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic materials, and particularly relates to a low specific surface area TiB2-TiC composite ceramic material and a preparation method thereof. BACKGROUND

[0002] Titanium diboride TiB2 and titanium carbide TiC are both high melting point compounds, and have the advantages of high hardness, high electrical conductivity, high temperature resistance, heat shock resistance, low density, etc. Although the hardness of the TiB2-TiC composite ceramic prepared by mixing TiB2 and TiC is lower than that of the single-phase ceramic at room temperature, the fracture toughness and wear resistance are both improved, and the chemical stability and hardness at a high temperature of ≥600 DEG C are also higher than those of the single-phase ceramic. Therefore, the TiB2-TiC composite ceramic is often used in parts working in extreme conditions such as high-speed cutting tools, high-temperature resistant parts, high-temperature wear-resistant parts, and nuclear reactor protection tiles, and has a good application prospect in the fields of chemical industry, metallurgy, nuclear industry, and military industry.

[0003] As a two-phase composite ceramic, the traditional preparation method of the TiB2-TiC composite ceramic is to prepare TiB2 and TiC respectively, and then to physically mix them. However, TiB2 and TiC are both high covalent bond content and high melting point powders, and lack liquid phase and crystal transformation during sintering, and have the characteristics of difficult sintering. Therefore, a sintering aid is added to form a liquid phase to promote the mass transfer process during sintering. However, when TiB2 and TiC are prepared separately, TiB2 is formed at a higher temperature, and although a powder with a very small specific surface area (1-5 m 2 / g) can be obtained, the particle size of the obtained TiB2 powder is relatively large, and TiB2 is extremely hard and difficult to crush; TiC can be formed at a lower temperature, avoiding the problem that TiC powder particles are prone to grow, and submicron particles can be formed, but the crystal form is incomplete, and fine pore gaps are present, which is reflected in a relatively large specific surface area value (20 m 2 / g or more). For the TiB2-TiC composite ceramic which belongs to superhard ceramic, it is very difficult to further process the sintered powder, and therefore a forming step is usually performed before sintering. For a complex shape, forming methods such as slip casting, die casting, and solidification injection molding which need to mix with a binder are used. When the specific surface area of the powder is relatively large, the powder tends to combine more binders, and the flowability of the slurry and the plastic material is poor, which is manifested in the system drying and poor forming performance on a macroscopic scale; if the amount of the binder is increased to improve the forming performance, the proportion of the powder is insufficient, and the performance of the sintered product is reduced.

[0004] In microstructure, larger specific surface area usually means more channels. For the preparation of TiB2-TiC composite ceramic, both TiB2 and TiC are high-melting-point low-diffusion-coefficient powders, and belong to difficult-to-sinter materials. Therefore, the combination of TiB2 and TiC is achieved by providing liquid phase by sintering aids during sintering to promote the dissolution-recrystallization process of TiB2 and TiC powders, so that the TiB2 and TiC powder particles grow together to form a whole. However, due to the surface tension of the liquid phase, it is difficult to enter the channels in the particles, resulting in difficulty in channel growth, and finally forming voids, which affects the density index of the product. At the same time, when TiB2 and TiC are physically mixed, local density is prone to be low due to uneven mixing in different parts. SUMMARY

[0005] The present application aims to provide a low specific surface area TiB2-TiC composite ceramic material and a preparation method thereof, which can obtain a TiB2-TiC composite ceramic material with few pores, complete shape, extremely low specific surface area and uniform composition.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0007] The present application provides a preparation method of a low specific surface area TiB2-TiC composite ceramic material, comprising the following steps:

[0008] Mixing a titanium source, water and a dispersing agent to obtain a dispersion liquid;

[0009] Mixing the dispersion liquid with a boron source, a carbon source, a high molecular grid agent and an initiator to perform cross-linking reaction to obtain a gel; the high molecular grid agent comprises acrylamide and N-N methylene bisacrylamide;

[0010] Drying and crushing the gel in sequence, and sintering the obtained gel particles to obtain a TiB2-TiC composite powder;

[0011] Removing carbon from the TiB2-TiC composite powder to obtain a low specific surface area TiB2-TiC composite ceramic material;

[0012] The specific surface area of the low specific surface area TiB2-TiC composite ceramic material is 1.0-6.0 m 2 / g.

[0013] Preferably, the titanium source comprises titanium dioxide; and the dispersing agent comprises one or more of polyethylene glycol, povidone K30, polyvinyl alcohol and sodium carboxymethyl cellulose;

[0014] The mass fraction of the dispersing agent in the dispersion liquid is 0.5-5.0%; and the mass ratio of the titanium source to water is (1-2):20.

[0015] Preferably, the boron source comprises boric acid, metaboric acid or boron oxide; the carbon source comprises sucrose, glucose, fructose or mannitol; and the molar ratio of the titanium source, the boron source and the carbon source is 1:(2-4):(2-5) in terms of titanium, boron and carbon atoms.

[0016] Preferably, the mass ratio of the acrylamide and N-N methylene bisacrylamide is 10:(0.25-0.3); and the mass ratio of the high-molecular mesh agent and water is (0.5-1.5):10.

[0017] Preferably, the initiator comprises ammonium persulfate, potassium persulfate or sodium persulfate; and the mass ratio of the initiator and acrylamide is (0.1-0.2):1.

[0018] Preferably, the temperature of the cross-linking reaction is <100℃, and the time is 7-15 min.

[0019] Preferably, the sintering temperature is 1460-1800℃, the holding time is >2h, the heating rate to the sintering temperature is >400℃ / h; and the sintering atmosphere is vacuum atmosphere or inert gas argon.

[0020] Preferably, the carbon removal temperature is 450-550℃, and the time is 2-4h.

[0021] The present application provides a low specific surface area TiB2-TiC composite ceramic material prepared by the preparation method.

[0022] The present application disperses the boron source, the titanium source and the carbon source in the high-molecular mesh formed by the high-molecular mesh agent under the action of the initiator to obtain a high-molecular mesh gel precursor with uniform mixing of titanium, boron and carbon elements, which ensures uniform mixing of the reaction raw materials and obtains microscopically uniformly mixed TiB2-TiC powder in the sintering process, and meanwhile, the carbon elements in the mesh reduce the specific surface area of the products TiB2 and TiC in the sintering process of the gel precursor, thereby obtaining a uniformly mixed low specific surface area TiB2-TiC composite ceramic material.

[0023] The present application adopts the high polymer gel grid method to prepare the TiB2-TiC composite ceramic material, first disperses the titanium source in water under the action of the dispersant to form a stable dispersed dispersion liquid, then adds the boron source and the carbon source into the dispersion liquid, simultaneously utilizes the high polymer grid agent and uses the initiator to initiate the gridding to form the gel, at this time the high polymer grid separates the uniformly dispersed boron, titanium and carbon atoms in the molecular scale grid; after the gel is dried and sintered, the gel is carbonized at high temperature to form the uniformly distributed carbon, the carbon first reacts with the titanium source to obtain the TiC, and the TiC reacts with the boron source to generate the TiB2; under the action of the grid, the TiC and the TiB2 crystals have sufficient space for growth, and meanwhile the existence of the carbon element in the grid also makes the crystals not excessively grow, so that the fine crystals with few pores, complete shape and extremely low specific surface area are obtained.

[0024] The present application adopts the high polymer network coating reaction raw material, and belongs to the composite dispersion of the dispersant, acrylamide and N-N methylene double acrylamide high polymer three-dimensional network structure on the gel precursor. The dispersant plays the steric hindrance dispersion role, the acrylamide increases the pH of the system, increases the electrostatic repulsion between the titanium dioxide powders (the isoelectric point of the titanium dioxide powder is pH=3.6), makes the titanium dioxide powders uniformly dispersed in the solution containing the boron source and the carbon source, and then forms the three-dimensional space network structure through the polymerization and crosslinking of the high polymer, separates the system from numerous micro-containers, plays the shielding and blocking role in space, further improves the dispersibility of the raw material, so that the gel precursor with the molecular level uniform mixing between the titanium source, the boron source and the carbon source is obtained, the mass transfer diffusion distance is greatly shortened, the titanium, boron and carbon elements are uniformly distributed in the high polymer grid for reaction, the TiB2 and TiC uniformly mixed powders are obtained, meanwhile the high polymer grid produces the hindering role in the reaction process, can prevent the mutual sintering and agglomeration of the products, and finally the small and dispersed TiB2-TiC composite powders are obtained.

[0025] The TiB2-TiC composite powder product prepared by the present application has small specific surface area, avoids the internal pores often appearing in the powders with large specific surface area, is more easily densified when further processed into ceramics, and is convenient for forming the ceramics with high density; meanwhile, the low specific surface area also can reduce the possibility of agglomeration when mixed in the subsequent sintering and additive mixing, and increase the uniformity when processed into ceramics.

[0026] The present application controls the proportion of TiC and TiB2 in the composite ceramic material by adjusting the proportion of titanium, boron and carbon. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The X-ray powder diffraction (XRD) diffraction chart of the TiB2-TiC composite ceramic material prepared in Example 1;

[0028] Figure 2A scanning electron microscope (SEM) image of the TiB2-TiC composite ceramic material prepared in Example 1;

[0029] Figure 3 A BET specific surface area measurement result graph of the TiB2-TiC composite ceramic material prepared in Example 1;

[0030] Figure 4 An XRD graph of the TiB2-TiC composite ceramic material prepared in Comparative Example 1. DETAILED DESCRIPTION

[0031] The present application provides a preparation method of a low specific surface area TiB2-TiC composite ceramic material, comprising the following steps:

[0032] Mixing a titanium source, water and a dispersing agent to obtain a dispersion liquid;

[0033] Mixing the dispersion liquid with a boron source, a carbon source, a high polymer grid agent and an initiator to perform a cross-linking reaction, and obtaining a gel; the high polymer grid agent comprises acrylamide and N-N methylene bisacrylamide;

[0034] Drying and crushing the gel in sequence, and sintering the obtained gel particles to obtain a TiB2-TiC composite powder;

[0035] Performing carbon removal on the TiB2-TiC composite powder to obtain a low specific surface area TiB2-TiC composite ceramic material;

[0036] The specific surface area of the low specific surface area TiB2-TiC composite ceramic material is 1.0-6.0 m 2 / g.

[0037] In the present application, if no special description is given, all the required preparation raw materials are commercially available goods which are well known to those skilled in the art.

[0038] The present application mixes a titanium source, water and a dispersing agent to obtain a dispersion liquid.

[0039] In the present application, the titanium source preferably comprises titanium dioxide; the purity of the titanium dioxide is ≥98%, and the particle size is all passed through a 325 mesh sieve. In the present application, the mass ratio of the titanium source to water is preferably (1-2):20, and more preferably (1-1.7):20.

[0040] In the present application, the dispersant preferably comprises one or more of polyethylene glycol, povidone K30, polyvinyl alcohol and sodium carboxymethyl cellulose; the molecular weight of the polyethylene glycol is preferably 6000-20000, more preferably 10000; the polyvinyl alcohol is preferably polyvinyl alcohol 088-20; when the dispersant is two or more of the above, the present application does not have a special limitation on the ratio of different types of dispersants, which can be adjusted according to actual needs. The present application uses a dispersant to increase the stability of the suspension formed by the titanium source and water.

[0041] In the present application, the mass fraction of the dispersant in the dispersion is preferably 0.5-5.0%, more preferably 0.75-1.12%; after dispersing the titanium source in water, the present application ultrasonically disperses for 30 min, adds a dispersant to the obtained suspension, and magnetically stirs for 2 h to form a dispersion.

[0042] After obtaining the dispersion, the present application mixes the dispersion with a boron source, a carbon source, a high-molecular meshing agent and an initiator to perform a cross-linking reaction and obtain a gel.

[0043] In the present application, the boron source preferably comprises boric acid, metaboric acid or boric oxide; the carbon source preferably comprises sucrose, glucose, fructose or mannitol.

[0044] In the present application, the molar ratio of the titanium source, the boron source and the carbon source is preferably 1:(2-4):(2-5), more preferably 1:(2.22-3.784):(2.94-5) in terms of titanium, boron and carbon atoms. The present application limits the above ratio of the titanium source, the boron source and the carbon source considering the volatilization or cracking of boron and carbon elements during the reaction. The special nature of TiC structure often results in the absence of carbon elements to form non-stoichiometric TiCx(x<1), and the excess carbon forms an amorphous structure, forming an amorphous peak on the X-ray powder diffraction spectrum, while inhibiting the increase of the specific surface area of the particles. At the same time, the amount of volatile carbon-containing small molecules formed by the meshing agent during high-temperature sintering fluctuates in a large range, and the volatilization of boron elements is inevitable. Therefore, the present application controls the boron element to be in excess, and the carbon element does not need to be in excess.

[0045] In the present application, the high-molecular meshing agent comprises acrylamide and N-N methylene bisacrylamide; the mass ratio of the acrylamide and the N-N methylene bisacrylamide is preferably 10:(0.25-0.3), more preferably 10:0.284; the mass ratio of the high-molecular meshing agent and water is preferably (0.5-1.5):10, more preferably 0.5:10. The present application limits the above ratio of the high-molecular meshing agent, which can form a gel when the meshing agent initiates a cross-linking reaction in the reaction system, and does not introduce too much carbon.

[0046] In the present application, the initiator preferably comprises ammonium persulfate, potassium persulfate or sodium persulfate; the mass ratio of the initiator to acrylamide is preferably (0.1-0.2):1, and more preferably 0.1784:1. The present application uses the initiator to initiate the cross-linking of the high-molecular mesh agent to form a gel.

[0047] In the present application, the boron source is added to the dispersion liquid and stirred magnetically for 30 min until the boron source is dissolved, then the carbon source is added and stirred magnetically for 30 min until the carbon source is dissolved, and then the high-molecular mesh agent is continuously added, stirred and heated in a water bath to 40℃, and kept at a constant temperature for 30 min, and then the initiator is added after dissolution and stirred for 30 min until dissolution, and then heated to the cross-linking reaction temperature. The present application does not have special limitations on the specific process of the mixing, dissolution and stirring, and can be performed according to the processes well known in the art.

[0048] In the present application, the cross-linking reaction temperature is preferably <100℃, and more preferably 65-70℃, and the time is preferably 7-15 min, and more preferably 8-11 min; and the cross-linking reaction is preferably performed under stirring.

[0049] After obtaining the gel, the present application sequentially performs drying and crushing on the gel, and performs sintering on the obtained gel particles to obtain a TiB2-TiC composite powder.

[0050] In the present application, the drying temperature is preferably 180-300℃, and more preferably 200℃, and the present application does not have special limitations on the time and mode of drying and the mode of crushing, and can be performed according to the modes well known in the art. The present application does not have special limitations on the particle size of the crushing, and can be adjusted according to actual needs; in the embodiments of the present application, in order to adapt to the graphite crucible used, the dried xerogel is crushed to pass through a 2 mm sieve.

[0051] In the present application, the sintering temperature is preferably 1460-1800℃, and more preferably 1500-1700℃, and further preferably 1600-1650℃; the holding time is preferably ≥2 h, and more preferably 2-2.5 h; the heating rate to the sintering temperature is preferably ≥400℃ / h, and more preferably 600℃ / h; the sintering atmosphere is preferably a vacuum atmosphere or an inert gas argon; the inert gas is preferably argon; and the present application does not have special limitations on the vacuum degree of the vacuum atmosphere, and can be adjusted according to actual needs.

[0052] After obtaining the TiB2-TiC composite powder, the present application performs carbon removal on the TiB2-TiC composite powder to obtain a low specific surface area TiB2-TiC composite ceramic material.

[0053] In the present application, the carbon removal temperature is preferably 450-550℃, and the carbon removal time is preferably 2-4h, more preferably 3h; the carbon removal is preferably carried out in an air atmosphere. The present application removes the incompletely reacted carbon by carbon removal, while avoiding the oxidation of TiC (the oxidation temperature of TiC is 600℃).

[0054] The present application provides a low specific surface area TiB2-TiC composite ceramic material prepared by the preparation method.

[0055] The technical solutions provided by the present application are described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present application.

[0056] In the following examples, the purity of the titanium dioxide used is ≥98%, and the particle size is 325 mesh.

[0057] Example 1

[0058] 10.00g (0.125mol) of titanium dioxide was dispersed in 200mL of water, ultrasonic dispersion for 30min, and a suspension was prepared. 1.5g of polyethylene glycol 6000 was added to the suspension, and magnetic stirring dispersion was carried out for 2h to form a polyethylene glycol 6000 mass fraction of 0.75% titanium dioxide dispersion. 15.48g (0.250mol) of boric acid was added to the dispersion, and magnetic stirring was carried out for 30min until the boric acid was dissolved. Then 17.858g (0.052mol) of sucrose was added, and the carbon element content was 0.626mol. Magnetic stirring was carried out for 30min until the sucrose was dissolved. Then 10g of acrylamide and 0.284g of N-N methylene bisacrylamide were added as meshing agents, and stirring and water bath heating to 40℃ were carried out. The temperature was kept at 40℃ for 30min, and then 1.784g of ammonium persulfate was added. Stirring and dissolution were carried out for 30min, and the temperature was raised to 70℃. After magnetic stirring for 7min, a high molecular meshing gel was formed. The gel was dried at 200℃, and then broken into 2mm gel particles.

[0059] The gel particles were loaded into a graphite crucible, and heated to 1600℃ at a rate of 600℃ / h in an induction furnace, and kept at 1600℃ for 2h under argon atmosphere. The obtained TiB2-TiC composite powder was heated to 550℃ for 3h to remove carbon, and a TiB2-TiC composite ceramic material was obtained.

[0060] Example 2

[0061] 10.00 g (0.125 mol) of titanium dioxide was dispersed in 200 mL of water, ultrasonic dispersion for 30 min, and prepared into a suspension. 1.5 g of polyethylene glycol 20000 was added to the suspension, and dispersed by magnetic stirring for 2 h to form a titanium dioxide dispersion liquid with a mass fraction of 0.75% of polyethylene glycol 20000. 15.48 g (0.250 mol) of boric acid was added to the dispersion liquid, and stirred magnetically for 30 min until the boric acid was dissolved. Then, 17.858 g (0.0522 mol) of sucrose, with a carbon element content of 0.626 mol, was added, and stirred magnetically for 30 min until dissolved. Acrylamide 10 g and N-N methylene bisacrylamide 0.284 g were added, and stirred and heated in a water bath to 40°C. The temperature was kept constant for 30 min, and then 1.784 g of ammonium persulfate was added, and stirred for 30 min until dissolved. The temperature was raised to 65°C, and a macromolecular grid gel was formed after magnetic stirring for 8 min. The gel was dried at 200°C, and then broken into gel particles of 2 mm in size.

[0062] The above gel particles were loaded into a graphite crucible, and heated in an induction furnace at a rate of 600°C / h to 1700°C, and kept at this temperature for 2 h under the protection of argon atmosphere. The obtained TiB2-TiC composite powder was heated at 550°C for 2 h to remove carbon, and a TiB2-TiC composite ceramic material was obtained.

[0063] Example 3

[0064] 10.00 g (0.125 mol) of titanium dioxide was dispersed in 200 mL of water, ultrasonic dispersion for 30 min, and prepared into a suspension. 1.5 g of polyethylene glycol 6000 was added to the suspension, and dispersed by magnetic stirring for 2 h to form a titanium dioxide dispersion liquid with a mass fraction of 0.75% of polyethylene glycol 6000. 29.27 g (0.473 mol) of boric acid was added to the dispersion liquid, and stirred magnetically for 30 min until the boric acid was dissolved. Then, 17.858 g (0.0522 mol) of sucrose, with a carbon element content of 0.626 mol, was added, and stirred magnetically for 30 min until dissolved. Acrylamide 10 g and N-N methylene bisacrylamide 0.284 g were added, and stirred and heated in a water bath to 40°C. The temperature was kept constant for 30 min, and then 1.784 g of ammonium persulfate was added, and stirred for 30 min until dissolved. The temperature was raised to 68°C, and a macromolecular grid gel was formed after magnetic stirring for 8 min. The gel was dried at 200°C, and then broken into gel particles of 2 mm in size.

[0065] The above gel particles were loaded into a graphite crucible, and heated in an induction furnace at a rate of 600°C / h to 1600°C, and kept at this temperature for 2 h under the protection of argon atmosphere. The obtained TiB2-TiC composite powder was heated at 550°C for 3 h to remove carbon, and a TiB2-TiC composite ceramic material was obtained.

[0066] Example 4

[0067] TiO2, 17.03 g (0.213 mol) was dispersed in 200 mL of water, and ultrasonic dispersion was carried out for 30 min to form a suspension. 2.25 g of polyethylene glycol 6000 was added to the suspension, and magnetic stirring was carried out for 2 h to form a dispersion of TiO2 with a mass fraction of 1.12% of polyethylene glycol 6000. 29.27 g (0.473 mol) of boric acid was added to the dispersion, and magnetic stirring was carried out for 30 min until the boric acid was dissolved. Then, 17.858 g of sucrose, with a carbon content of 0.626 mol, was added, and magnetic stirring was carried out for 30 min until the sucrose was dissolved. Then, 10 g of acrylamide and 0.284 g of N-N methylene bisacrylamide were added, and stirring was carried out while heating in a water bath to 40°C. The temperature was kept at 40°C for 30 min, and then 1.784 g of ammonium persulfate was added. Stirring was carried out for 30 min until the ammonium persulfate was dissolved. The temperature was raised to 65°C, and magnetic stirring was carried out for 11 min to form a macromolecular mesh gel. The gel was dried at 200°C, and then broken into gel particles with a size of 2 mm.

[0068] The gel particles were loaded into a graphite crucible, and heated in an induction furnace at a rate of 600°C / h to 1650°C, and kept at this temperature for 2 h under an argon atmosphere. The resulting TiB2-TiC composite powder was heated at 450°C for 3 h to remove carbon, and a TiB2-TiC composite ceramic material was obtained.

[0069] Comparative Example 1

[0070] Without using a macromolecular mesh gel:

[0071] TiO2, B2O3 and elemental C powder were mixed in a mortar in a molar ratio of 1:1:5.34 (mass ratio of 10 g:15.48 g:8 g) by dry mixing. The mixed powder was loaded into a graphite crucible, and heated in an induction furnace at a rate of 600°C / h to 1600°C, and kept at this temperature for 2 h under an argon atmosphere. The resulting TiB2-TiC composite powder was heated at 550°C for 3 h to remove carbon, and a TiB2-TiC composite ceramic material was obtained.

[0072] Characterization and performance testing

[0073] Figure 1 The X-ray powder diffraction (XRD) pattern of the TiB2-TiC composite ceramic material prepared in Example 1 is shown in Figure 1. Figure 1 As can be seen, the product is composed of two phases of well-crystallized TiB2 and TiC, and no other crystalline phase is present.

[0074] Figure 2 The scanning electron microscope (SEM) image of the TiB2-TiC composite ceramic material prepared in Example 1 is shown in Figure 2. Figure 2 As can be seen, the product is a monodisperse powder composed of a uniform mixture of large thick flake-shaped crystals and small point-shaped particles, and no obvious agglomeration is present.

[0075] Figure 3 BET specific surface area measurement result graph of TiB2-TiC composite ceramic material prepared in Example 1; from Figure 3 It can be seen that the specific surface area (BET method) of the product is 1.3118m 2 / g, and the data is linear.

[0076] The mass ratio of TiB2 to TiC in the TiB2-TiC composite ceramic material prepared in Example 1 is estimated to be 100:43.9 using XRD diffraction data, and the tested specific surface area is 1.3118m 2 / g.

[0077] Figure 4 XRD graph of TiB2-TiC composite ceramic material prepared in Comparative Example 1, from Figure 4 It can be seen that the mass ratio of TiB2 to TiC is 100:45.4 (the theoretical value of TiB2:TiC is 100:50), and there is an unidentified phase in Figure 4 , indicating that the reaction is not complete at this temperature, and there is an intermediate product left over, and part of the carbon has not been converted into TiC.

[0078] The specific surface area of the TiB2-TiC composite ceramic material prepared in Comparative Example 1 is tested by BET method to be 26.385m 2 / g.

[0079] In addition, it is tested that the mass ratio of TiB2 to TiC in the TiB2-TiC composite ceramic material prepared in Example 2 is 100:19.9, and the tested specific surface area is 2.2546m 2 / g.

[0080] The mass ratio of TiB2 to TiC in the TiB2-TiC composite ceramic material prepared in Example 3 is 100:56.0, and the tested specific surface area is 5.0559m 2 / g.

[0081] The mass ratio of TiB2 to TiC in the TiB2-TiC composite ceramic material prepared in Example 4 is 100:105.1, and the tested specific surface area is 5.1602m 2 / g.

[0082] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for producing a low specific surface area TiB2-TiC composite ceramic material, characterized by, Includes the following steps: A dispersion is obtained by mixing a titanium source, water, and a dispersant. The dispersion was mixed with a boron source, a carbon source, a polymeric meshing agent, and an initiator to carry out a crosslinking reaction, thereby obtaining a gel; the polymeric meshing agent included acrylamide and NN methylenebisacrylamide. The gel was dried and crushed in sequence, and the resulting gel particles were sintered to obtain TiB2-TiC composite powder; The TiB2-TiC composite powder was decarbonized to obtain a low specific surface area TiB2-TiC composite ceramic material. The low specific surface area TiB2-TiC composite ceramic material has a specific surface area of 1.0-6.0 m 2 / g; The molar ratio of the titanium source, boron source and carbon source, based on titanium, boron and carbon atoms, is 1:(2~4):(2~5); The mass ratio of acrylamide to N,N-methylenebisacrylamide is 10:(0.25~0.3).

2. The preparation method according to claim 1, characterized in that, The titanium source includes titanium dioxide; the dispersant includes one or more of polyethylene glycol, povidone K30, polyvinyl alcohol, and sodium carboxymethyl cellulose. The mass fraction of the dispersant in the dispersion is 0.5-5.0%; the mass ratio of the titanium source to water is (1-2):

20.

3. The preparation method according to claim 1, characterized in that, The boron source includes boric acid, metaboric acid, or boron oxide; the carbon source includes sucrose, glucose, fructose, or mannitol.

4. The preparation method according to claim 1, characterized in that, The mass ratio of the polymeric meshing agent to water is (0.5~1.5):

10.

5. The preparation method according to claim 1, characterized in that, The initiator includes ammonium persulfate, potassium persulfate, or sodium persulfate; the mass ratio of the initiator to acrylamide is (0.1~0.2):

1.

6. The preparation method according to claim 1, characterized in that, The cross-linking reaction is carried out at a temperature of <100 ℃ for 7~15 min.

7. The preparation method according to claim 1, characterized in that, The sintering temperature is 1460~1800 ℃, the holding time is ≥2 h, and the heating rate to the sintering temperature is ≥400 ℃ / h; the sintering atmosphere is a vacuum atmosphere or an inert gas argon.

8. The preparation method according to claim 1, characterized in that, The carbon removal temperature is 450~550 ℃, and the time is 2~4 h.

9. The low specific surface area TiB2-TiC composite ceramic material prepared by the preparation method according to any one of claims 1 to 8.

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