CN117567160A - A TiB2-based composite ceramic and rapid preparation method - Google Patents

Abstract

The invention relates to a rapid preparation method of _TiB2 -based composite ceramics and belongs to the field of composite materials. The method is to granulate a certain proportion of Ti powder and B ₄ C powder, and then mix the granulated particles with TiB ₂ powder evenly to obtain a mixed powder; a discharge plasma sintering system is used to sinter the mixed powder Process to obtain the composite ceramic; the composite ceramic prepared by this method has high strength, high hardness, high strength and fracture toughness, and the overall performance is greatly improved, making it an ideal high-performance composite ceramic material.

Description

A TiB2-based composite ceramic and rapid preparation method

Technical field

The invention relates to a rapid preparation method of _TiB2 -based composite ceramics and belongs to the field of composite materials.

Background technique

With the continuous development of advanced material technology and its gradual use in the upgrading of weapons and equipment, the penetration resistance of armor structures has also been greatly improved. The application of ceramic materials effectively improves the comprehensive application performance of armor, and their mechanical behavior plays a crucial role in the application of armor protection in practical engineering.

TiB ₂ ceramic has strong application value in the field of armor protection due to its high hardness, low density, high wear resistance and high temperature stability. With the rapid advancement of sintering technology and scientific theories, the difficult-to-sinter characteristics of TiB ₂ ceramics have gradually been improved. Recent studies have shown that adding metals such as Fe, Co, Ni, etc. to ceramic materials can not only lower the sintering temperature and increase the density, but also use Its plastic deformation prevents crack expansion and improves high temperature toughness. The metal phase reacts with the _TiB2 matrix phase to form a new phase that can pin the grain boundaries, refine the grains, and improve the strength, but this new phase will also reduce the overall hardness of the material.

On this basis, it is considered to add B ₄ C and Ti at the same time to avoid the disadvantages of directly adding the metal phase. At the same time, the in-situ reaction between B ₄ C and Ti can be used to reduce the sintering temperature, and the newly generated fine TiB ₂ particles and TiC can be used to improve the strength and toughness of TiB _2- based composite ceramic materials. In addition, from the perspective of facilitating sintering and solid-phase reaction, the granulation process can solve specific problems such as uneven powder, poor fluidity, and preferential reaction in the sintering process.

However, due to the complex preparation process, there has been no detailed report so far.

Contents of the invention

In view of this, the purpose of the present invention is to provide a rapid preparation method for TiB ₂ -based composite ceramics. The method uses a discharge plasma sintering system to preferentially granulate B ₄ C and Ti powder, and then mixes it with TiB ₂ powder to achieve TiB Rapid, controllable and low-cost preparation of _2- base composite ceramics. The final sintered product maintains the advantages of _TiB2 ceramics, and the TiC phase generated by the reaction provides the possibility of higher strength, fracture toughness and wear resistance, which helps to improve the overall performance and is the ideal ceramic in future composite protective materials. Ideal choice of materials.

The object of the present invention is achieved by the following technical solutions:

A rapid preparation method of _TiB2- based composite ceramics. The steps of the method are as follows:

(1) Add Ti powder and B ₄ C powder into a ball milling tank, add PVA deionized water solution as the ball milling medium, ball mill to mix evenly, and granulate to obtain Ti-B ₄ C granulated powder. Then add the granulated powder and TiB ₂ powder into the ball mill tank, and mix the powder evenly without adding ball milling media;

Among them, the mass ratio of the Ti powder and B ₄ C powder is 3:1; the solid content of the slurry is 50%, in which PVA accounts for 0.5% of the total powder mass.

The particle size of the Ti powder is preferably ≤10 μm; the particle size of the B ₄ C powder is preferably ≤3 μm; and the PVA preferably has an alcoholysis degree of 88-89 mol%.

The ball mill adopts SM-QB planetary ball mill;

The preferred ball milling parameters are: the ball milling medium is PVA deionized water solution; the ball-to-material ratio is 2 to 5:1; the ball mill speed is 250r/min, and the ball milling time is 2 to 4 hours;

Among them, the grinding balls are preferably composed of large, medium and _small ZrO balls with a mass ratio of 1:1:2; the diameter of the large _ZrO balls is 15mm, the diameter of the medium _ZrO balls is 10mm, and the _diameter of the small ZrO balls is Diameter is 5mm;

The granulation adopts Wuxi Dongsheng spray dryer;

The granulation parameters are preferably: the pumping speed is 40 rpm, and the discharge outlet temperature is 200°C;

(2) Add (Ti+B4C) granulated powder and _TiB2 powder into the ball milling tank of the SM-QB planetary ball mill, and mix evenly without adding ball milling media to obtain a mixed powder.

Wherein, the mass ratio of the (Ti-B ₄ C) granulated powder and TiB ₂ powder is 0.14 to 4:1; the particle size of the TiB ₂ powder is preferably ≤5 μm.

The ball milling parameters are preferably as follows: the ball mill speed is 150r/min, and the ball milling time is 10min;

(3) Use a discharge plasma sintering system to sinter the mixed powder to obtain the TiB ₂ -based composite ceramic of the present invention;

Among them, the sintering process is:

When the vacuum degree is <10Pa and the initial pressure is 0.2~1MPa, first heat up at a heating rate of 100~150℃/min. When the temperature rises to 800~900℃, adjust the heating rate to 10~30℃/min; when the temperature rises When the temperature reaches 950~1050℃ and the vacuum degree is <10Pa, adjust the heating rate to 50-80℃/min; when the temperature rises to 1200~1250℃, increase the pressure; when the temperature rises to 1450~1650℃, the pressure reaches 40 ~70MPa, keep heat and pressure for 3~8 minutes; then keep the pressure unchanged, cool to below 900℃ with the furnace, release the pressure, and cool with the furnace to below 100℃.

Beneficial effects:

(1) The method of the present invention uses a mixed powder of (Ti+B4C) granulated powder and _TiB2 powder as raw material, and uses a discharge plasma sintering system for sintering. The particle surface of the mixed powder will be cleaned and activated by the electric field during the sintering process. , so that it can fully react at a lower sintering temperature. The TiB ₂ composite ceramic obtained by sintering has a low densification temperature, high density, high hardness, good toughness, and excellent comprehensive properties; the TiB ₂ based composite ceramic has The density reaches 98%, the Vickers hardness value reaches 25Gpa, the bending strength value reaches 596MPa, and the fracture toughness value reaches 5.9MPa·m ^1/2 . It has great application prospects.

(2) The rapid preparation method provided by the present invention is simple and easy to implement, has a short cycle, is highly practical, and is conducive to industrialization.

Description of the drawings

Figure 1 shows the spherical (Ti+B ₄ C) granulated powder prepared in Examples 1 to 3.

Figure 2 is the XRD pattern of (Ti+B ₄ C) granulated powder and the TiB _2- based composite ceramic prepared in Example 3.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The average particle size of the Ti powder in the following examples is 10 μm, and the purity is ≥99.0%; the average particle size of the B ₄ C powder is 5 μm, and the purity is 99.8%; the average particle size of the TiB ₂ powder is 5 μm, and the purity is 99.5 %.

Example 1

A rapid preparation method of _TiB2- based composite ceramics. The steps of the method are as follows:

(1) Add 723g Ti powder and 277g B ₄ C powder into the ball mill tank. Add the grinding ball and PVA deionized water solution as the ball milling medium, and ball mill for 2 hours at a speed of 250 r/min to mix evenly. Pour the mixed slurry into a spray dryer, steam and granulate at a pumping speed of 40 rpm and a discharge outlet temperature of 200°C to produce spherical (Ti+B4C) granulated powder.

(2) Add 1.8g (Ti+B4C) granulated powder and 13.2g _TiB2 powder into the ball milling tank of the SM-QB planetary ball mill, without adding grinding balls and absolute ethanol; at a speed of 150r/min, 10min Mix evenly to obtain mixed powder.

(3) Put 15g of mixed powder into a graphite mold with an inner diameter of 20mm, then wrap the graphite mold with asbestos felt and put it into the discharge plasma sintering system. Set the initial vacuum degree in the furnace cavity to <10Pa and the initial pressure to 0.2MPa. Heating is carried out at a heating rate of 150℃/min. When the temperature rises to 900℃, there is obvious gas release at this stage, and the air pressure in the furnace cavity increases. Adjust the heating rate to 30℃/min; when the temperature is higher than 1050℃ , when the vacuum degree is <10Pa, adjust the heating rate to 60°C/min; when the temperature rises to 1250°C, apply pressure; when the temperature rises to 1650°C and the pressure reaches 70MPa, keep the heat and pressure for 8 minutes; then keep the pressure unchanged and continue with the furnace Cool to below 900°C, remove the pressure, and then cool in the furnace to below 100°C. Take out the sintered ceramic block, use ethanol and deionized water to clean the surface of the ceramic, and obtain TiB _2- based composite ceramics.

The actual density of the TiB _2- based composite ceramic is 4.42g/cm ³ , the sample thickness is 10mm, the density is 97.6%, the hardness is 23~25Gpa, the bending strength value is 537~564MPa, and the fracture toughness is 5.2~5.7MPa·m ^1/2 .

Example 2

A rapid preparation method of _TiB2- based composite ceramics. The steps of the method are as follows:

(1) Add 723g Ti powder and 277g B ₄ C powder into the ball mill tank. Add the grinding ball and PVA deionized water solution as the ball milling medium, and ball mill for 2 hours at a rotation speed of 250r/min to mix evenly. Pour the mixed slurry into a spray dryer, steam and granulate at a pumping speed of 40 rpm and a discharge outlet temperature of 200°C to produce spherical (Ti+B4C) granulated powder.

(2) Add 4.5g (Ti+B4C) granulated powder and 10.5g _TiB2 powder into the ball milling tank of the SM-QB planetary ball mill, without adding grinding balls and absolute ethanol; at a speed of 150r/min, 10min Mix evenly to obtain mixed powder.

(3) Put 15g of mixed powder into a graphite mold with an inner diameter of 20mm, then wrap the graphite mold with asbestos felt and put it into the discharge plasma sintering system. Set the initial vacuum degree in the furnace cavity to <10Pa and the initial pressure to 0.2MPa. Raise the temperature at a heating rate of 100°C/min. When the temperature rises to 850°C, the in-situ reaction begins to occur. There is obvious outgassing at this stage, and the air pressure in the furnace cavity increases. Adjust the heating rate to 10°C/min; When the temperature is higher than 950℃ and the vacuum degree is <10Pa, adjust the heating rate to 80℃/min; when the temperature rises to 1200℃, apply pressure; when the temperature rises to 1590℃ and the pressure reaches 50MPa, keep the temperature and pressure for 5 minutes; then maintain The pressure remains unchanged, and the furnace is cooled to below 900°C. The pressure is released, and the furnace is cooled to below 100°C. The sintered ceramic block is taken out, and the surface of the ceramic is cleaned with ethanol and deionized water to obtain TiB _2- based composite ceramics. .

The actual density of the TiB _2- based composite ceramic is 4.45g/cm ³ , the sample thickness is 10mm, the density is 97.8%, the hardness is 21~23Gpa, the bending strength value is 545~572MPa, and the fracture toughness is 5.4~5.9MPa·m ^1/2 .

Example 3

A rapid preparation method of _TiB2- based composite ceramics. The steps of the method are as follows:

(1) Add 723g Ti powder and 277g B ₄ C powder into the ball mill tank. Add the grinding ball and PVA deionized water solution as the ball milling medium, and ball mill for 2 hours at a rotation speed of 250r/min to mix evenly. Pour the mixed slurry into a spray dryer, steam and granulate at a pumping speed of 40 rpm and a discharge outlet temperature of 200°C to produce spherical (Ti+B4C) granulated powder.

(2) Add 12g (Ti+B4C) granulated powder and 3g _TiB2 powder into the ball milling tank of the SM-QB planetary ball mill without adding grinding balls and absolute ethanol; mix evenly for 10 minutes at a speed of 150r/min. , to obtain mixed powder.

(3) Put 15g of mixed powder into a graphite mold with an inner diameter of 20mm, then wrap the graphite mold with asbestos felt and put it into the discharge plasma sintering system. Set the initial vacuum degree in the furnace cavity to <10Pa and the initial pressure to 0.2MPa. Raise the temperature at a heating rate of 100°C/min. When the temperature rises to 800°C, the in-situ reaction begins to occur. At this stage, there is obvious outgassing, and the air pressure in the furnace cavity increases. Adjust the heating rate to 10°C/min; When the temperature is higher than 1050℃ and the vacuum degree is <10Pa, adjust the heating rate to 50℃/min; when the temperature rises to 1200℃, apply pressure; when the temperature rises to 1450℃ and the pressure reaches 40MPa, keep the temperature and pressure for 3 minutes; then maintain The pressure remains unchanged, and the furnace is cooled to below 900°C. The pressure is released, and the furnace is cooled to below 100°C. The sintered ceramic block is taken out, and the surface of the ceramic is cleaned with ethanol and deionized water to obtain TiB _2- based composite ceramics. .

The actual density of the TiB _2- based composite ceramic is 4.45g/cm ³ , the sample thickness is 10mm, the density is 97.8%, the hardness is 22~24Gpa, the bending strength value is 554~596MPa, and the fracture toughness is 5.5~5.8MPa·m ^1/2 .

Claims (8)

1. A _TiB2- based composite ceramic and a rapid preparation method, characterized by the following steps: (1) Add Ti powder and B ₄ C powder into the ball mill tank in proportion, add grinding balls and PVA deionized water solution as ball milling medium and mix evenly. Then pour the mixed slurry into a spray dryer, steam and granulate to obtain spherical (Ti+B4C) granulated powder; (2) Add (Ti+B4C) granulated powder to _TiB2 powder and mix evenly without adding grinding ball media to obtain a mixed powder; (3) Put the mixed powder into the discharge plasma sintering system, first raise the sintering temperature to T ₁ , and then increase the sintering pressure to 40~70MPa during the process of raising the sintering temperature to T ₂ , and keep the temperature and pressure for 3min~8min; Lower the temperature and cool to below 900°C in the furnace. Release the pressure and cool to below 100°C in the furnace; where T ₁ =1200~1250°C and T ₂ =1450~1650°C. 2. A TiB _2- based composite ceramic according to claim 1, characterized in that: the particle size of Ti powder is preferably ≤10 μm; the particle size of B ₄ C powder is preferably ≤3 μm; and the preferred alcoholysis degree of PVA is 88-89 mol%. . 3. A TiB _2- based composite ceramic according to claim 1, characterized in that: the mass ratio of Ti powder and B ₄ C powder is 3:1; the solid content of the slurry is 50%, wherein PVA accounts for the total powder 0.5% of mass. 4. A TiB _2- based composite ceramic according to claim 1, characterized in that: when the granulated powder is mixed, the ball milling medium is PVA deionized aqueous solution; the ball-to-material ratio is 2 to 5:1; the ball mill speed is 250r/min , the ball milling time is 2 to 4 hours. 5. A TiB _base composite ceramic according to claim 1, characterized in that: the grinding balls are preferably composed of large, medium and small ZrO _balls with a mass ratio of 1:1:2; the large _ZrO balls The diameter of the ZrO 2 ball is 15mm, the diameter of the medium ZrO ₂ ball is 10mm, and the diameter of the small ZrO ₂ ball is 5mm. 6. A TiB _2- based composite ceramic according to claim 1, characterized in that: the granulation parameters are preferably: the pumping speed is 40 rpm, and the outlet temperature is 200°C. 7. A TiB2 _- based composite ceramic according to claim 1, characterized in that when (Ti+ _B4C ) granulated powder and _TiB2 are mixed, the ball milling parameters are preferably: the ball mill speed is 150r/min, and the ball milling speed is 150r/min. The time is 10 minutes; the particle size of TiB ₂ powder is preferably ≤5 μm; the mass ratio of (Ti+B ₄ C) granulated powder to TiB ₂ powder is 0.14 to 4:1. 8. A _TiB2- based composite ceramic according to any one of claims 1 to 7, characterized in that: the specific method for raising the temperature of the discharge plasma sintering system to _T1 is that the initial vacuum degree in the furnace cavity is <10Pa, The initial pressure is 0.2~1MPa, and the temperature is first raised at a heating rate of 100~150℃/min. When the temperature rises to _T3 , adjust the heating rate to 10~30℃/min; when the temperature rises to _T4 , and the vacuum degree When <10Pa, adjust the heating rate to 50~80℃/min; continue to heat up to _T1 ; _T3 = 800~900℃, _T4 = 950~1050℃.