阅读说明：本技术 基于高频脉冲电流烧结制备的多孔钛铝合金及其制备方法 (Porous titanium-aluminum alloy prepared based on high-frequency pulse current sintering and preparation method thereof ) 是由 陈洪胜 焦志明 段德盛 王文先 刘润爱 杨涛 于 2020-11-10 设计创作，主要内容包括：本发明提供一种基于高频脉冲电流烧结制备的多孔钛铝合金及其制备方法,属于多孔钛铝合金制备的技术领域,使用碳酸钾颗粒作为造孔剂制造了Ti-Al合金多孔材料,利用碳酸钾在水和乙醇中的溶解性的差异,实现了物理成孔的目的。通过高频脉冲电流烧结,可以以很快的烧结速率制备样品。样品的孔径大小可以通过调节碳酸钾颗粒的孔径来调节,而且可以获得最大的孔隙率。烧结之后对试样进行热处理,使未反应的钛和铝颗粒可以完全进行扩散反应,得到均匀的Ti-Al合金多孔材料。(The invention provides a porous titanium-aluminum alloy prepared based on high-frequency pulse current sintering and a preparation method thereof, belongs to the technical field of preparation of porous titanium-aluminum alloys, and aims to realize physical pore-forming by using potassium carbonate particles as a pore-forming agent to prepare a Ti-Al alloy porous material and utilizing the solubility difference of potassium carbonate in water and ethanol. By high frequency pulse current sintering, samples can be prepared at a very fast sintering rate. The pore size of the sample can be adjusted by adjusting the pore size of the potassium carbonate particles, and the maximum porosity can be obtained. And (3) carrying out heat treatment on the sample after sintering to ensure that unreacted titanium and aluminum particles can completely carry out diffusion reaction to obtain the uniform Ti-Al alloy porous material.)

1. A method for preparing porous titanium-aluminum alloy based on high-frequency pulse current sintering is characterized by comprising the following steps:

s1, preparing mixed powder

Weighing 325-mesh titanium powder and 300-mesh aluminum powder according to the mass ratio of 1:2, and performing low-speed ball milling and mixing at the rotating speed of 250 r/min;

s2, coating the surface of potassium carbonate to obtain mixed powder

Wetting potassium carbonate particles: pouring potassium carbonate powder into a container, adding ethanol into the container, and uniformly stirring;

filtering: filtering the potassium carbonate particles from the ethanol;

coating binary mixed powder: quickly putting the potassium carbonate particles with wet surfaces obtained after filtration into Ti-Al mixed powder, so that the surfaces of the potassium carbonate particles are coated with a layer of titanium and aluminum particles;

sieving: screening the obtained mixed powder by using a fine screen to remove redundant titanium powder and aluminum powder to obtain uniform potassium carbonate particles with surfaces coated with binary mixed powder;

s3, sintering

Sintering the mixed powder by using high-frequency pulse current, wherein the sintering parameters are as follows:

degree of vacuum 10^-2And the following;

the temperature rise curve is divided into two stages of quick temperature rise and slow temperature rise, and the temperature rise rate of the quick temperature rise is as follows: 80 ℃/min, the temperature rise time is as follows: and (3) 10min, wherein the heating rate of the slow heating is as follows: 25 ℃/min, the temperature rise time is as follows: 4min, finally heating to 900 ℃ and preserving heat for 30 min;

s4, polishing

Polishing a disc-shaped sample obtained by sintering high-frequency pulse current by using silicon carbide abrasive paper with the roughness of 400, removing graphite adhered to the upper surface, the lower surface and the circumferential side surface of the sample, keeping the surface of the sample clean, and ensuring that the surface has open holes connected with the inside of the sample;

s5, forming holes

Putting a sample with a good open pore structure on the surface into a container, adding clear water into the container, and ensuring that the sample is completely immersed into the clear water until potassium carbonate is dissolved in the water;

secondly, taking out the sample from the container, washing the sample with clear water, and drying the sample to obtain the titanium-aluminum porous alloy material with open pores;

s6, heat treatment

And (3) putting the sample without the potassium carbonate pore-forming agent into a tubular heating furnace for heat treatment, wherein the heating rate is 10 ℃/min, the time is 60min, the final temperature is 600 ℃, and the temperature is kept for 30min, so that titanium and aluminum particles can fully perform diffusion reaction, and uniform titanium-aluminum binary alloy is obtained.

2. The method for preparing the porous titanium-aluminum alloy based on the high-frequency pulse current sintering as claimed in claim 1, wherein in the step S2, the potassium carbonate powder is 80 meshes, and the potassium carbonate particles are filtered from the ethanol by using an 80-mesh screen.

3. The method for preparing the porous titanium-aluminum alloy based on the high-frequency pulse current sintering as claimed in claim 1, wherein in the step S3, sintering is performed by using a spark plasma sintering device, which comprises the following steps:

checking in an early stage: checking whether the oil level of the vacuum pump (7) is normal, whether the cooling system (1) is normal, and whether a manual pressure control knob (15) and a current manual adjusting knob (23) return to zero;

starting up: turning on a main power switch, a power supply of the cooling system (1), pressing down a water pump and a refrigeration knob, turning on a power switch (19) of the control cabinet, and turning on a computer;

opening the furnace chamber: closing the vacuum meter (16) and opening the furnace door;

assembling the die: filling a piece of graphite paper below the die, pouring the weighed sample powder into the die cavity, covering a layer of graphite paper on the upper surface after compaction, putting an upper pressure head, and rotating the upper pressure head for several circles to uniformly distribute the powder in the die cavity;

putting the mold into the furnace chamber, closing the furnace chamber: placing a mould in the center of a graphite cushion block, padding a piece of graphite paper between the mould and the graphite cushion block, placing another graphite cushion block on the mould, pressing a two-hand switch (4) after placing the mould, pressing the graphite cushion block and the mould tightly, inserting a thermocouple into a temperature measuring hole on the mould, and closing a furnace door;

sixthly, vacuumizing: confirming that the air release valve is in a closed state, opening a vacuum meter (16), and then vacuumizing until the vacuum degree reaches 10^-2Or lower, proceeding to the next step;

setting a temperature control meter, setting a heating program: setting a temperature rise curve, dividing the temperature rise curve into two stages of slow temperature rise and fast temperature rise, finally raising the temperature to 900 ℃, and preserving the temperature for 30 min;

setting data acquisition software: opening related software on a control computer, and recording data such as temperature, voltage, current and the like in the sintering process;

ninthly, sintering: setting a heating mode as automatic heating, turning on a sintering power supply and starting automatic heating;

and c, closing vacuum after sintering is finished, and taking out a sample: closing a sintering power switch (20), unloading pressure, stopping data software acquisition, storing a data curve, cooling for half an hour, closing vacuum and taking out a sample when the temperature of the mould is lower than 150 ℃;

⑪ shut down instrument: and closing the furnace chamber, vacuumizing, and then sequentially closing power supplies of all parts of the sintering furnace.

4. The method for preparing the porous titanium-aluminum alloy based on the high-frequency pulse current sintering of claim 1, wherein the step S5 further comprises slightly shaking the beaker to promote the potassium carbonate to dissolve in the water, stopping heating after 10min, continuously soaking the sample in the water, and standing for 24 h.

5. A porous titanium-aluminum alloy, which is prepared by the method for preparing the porous titanium-aluminum alloy based on high-frequency pulse current sintering according to any one of claims 1 to 4.

Technical Field

The invention belongs to the technical field of preparation of porous titanium-aluminum alloy, and particularly discloses porous titanium-aluminum alloy prepared based on high-frequency pulse current sintering and a preparation method thereof.

Background

The Ti-Al based porous material has the common advantages of ceramics and metals because most of the bonding bonds are covalent bonds and a small amount of metal bonds are also present. The high-temperature-resistant aluminum alloy has low density, high melting point, good strength, better corrosion resistance and oxidation resistance at high temperature, and is commonly used in the automobile industry and the energy industry.

At present, the method for preparing the Ti-Al porous material mainly adopts a solid-solid diffusion reaction at a low heating rate or a solid-liquid thermal explosion reaction at a high heating rate, and the porosity and the pore size of the Ti-Al alloy porous material prepared by the methods are very limited.

Disclosure of Invention

The invention aims to provide a porous titanium-aluminum alloy prepared based on high-frequency pulse current sintering and a preparation method thereof.

In order to achieve the aim, the invention provides a method for preparing a porous titanium-aluminum alloy based on high-frequency pulse current sintering, which comprises the following steps:

s1, preparing mixed powder

Weighing 325-mesh titanium powder and 300-mesh aluminum powder according to the mass ratio of 1:2, and performing low-speed ball milling and mixing at the rotating speed of 250 r/min;

s2, coating the surface of potassium carbonate to obtain mixed powder

Wetting potassium carbonate particles: pouring potassium carbonate powder into a container, adding ethanol into the container, and uniformly stirring;

filtering: filtering the potassium carbonate particles from the ethanol;

coating binary mixed powder: quickly putting the potassium carbonate particles with wet surfaces obtained after filtration into Ti-Al mixed powder, so that the surfaces of the potassium carbonate particles are coated with a layer of titanium and aluminum particles;

sieving: screening the obtained mixed powder by using a fine screen to remove redundant titanium powder and aluminum powder to obtain uniform potassium carbonate particles with surfaces coated with binary mixed powder;

s3, sintering

Sintering the mixed powder by using high-frequency pulse current, wherein the sintering parameters are as follows:

degree of vacuum 10^-2And the following;

the temperature rise curve is divided into two stages of rapid temperature rise and slow temperature rise, wherein the initial temperature is as follows: the temperature rise rate of the rapid temperature rise at 0 ℃ is as follows: 80 ℃/min, the temperature rise time is as follows: and (3) 10min, wherein the heating rate of the slow heating is as follows: 25 ℃/min, the temperature rise time is as follows: 4min, finally heating to 900 ℃ and preserving heat for 30 min;

s4, polishing

Polishing a disc-shaped sample obtained by sintering high-frequency pulse current by using silicon carbide abrasive paper with the roughness of 400, removing graphite adhered to the upper surface, the lower surface and the circumferential side surface of the sample, keeping the surface of the sample clean, and ensuring that the surface has open holes connected with the inside of the sample;

s5, forming holes

Putting a sample with a good open pore structure on the surface into a container, adding clear water into the container, and ensuring that the sample is completely immersed into the clear water until potassium carbonate is dissolved in the water;

secondly, taking out the sample from the container, washing the sample with clear water, and drying the sample to obtain the titanium-aluminum porous alloy material with open pores;

s6, heat treatment

Placing the sample with the potassium carbonate pore-forming agent removed into a tubular heating furnace for heat treatment, wherein the initial temperature is as follows: the temperature rise rate is 10 ℃/min at 0 ℃, the time is 60min, the final temperature is 600 ℃, and the temperature is kept for 30min, so that the titanium and the aluminum particles can fully perform diffusion reaction, and the uniform titanium-aluminum binary alloy is obtained.

In the above step S2, the potassium carbonate powder was 80 mesh, and the potassium carbonate particles were filtered from ethanol using an 80 mesh screen.

In the step S3, the sintering process is performed by using a spark plasma sintering apparatus, and includes the following steps:

checking in an early stage: checking whether the oil level of the vacuum pump (7) is normal, whether the cooling system (1) is normal, and whether a manual pressure control knob (15) and a current manual adjusting knob (23) return to zero;

starting up: turning on a main power switch, a power supply of the cooling system (1), pressing down a water pump and a refrigeration knob, turning on a power switch (19) of the control cabinet, and turning on a computer;

opening the furnace chamber: closing the vacuum meter (16), opening the air release valve, closing the air release valve after the vacuum conversion indicator lamp is turned on, and opening the furnace door;

assembling the die: filling a piece of graphite paper below the die, pouring the weighed sample powder into the die cavity, covering a layer of graphite paper on the upper surface after compaction, putting an upper pressure head, and rotating the upper pressure head for several circles to uniformly distribute the powder in the die cavity;

putting the mold into the furnace chamber, closing the furnace chamber: placing a mould in the center of a graphite cushion block, padding a piece of graphite paper between the mould and the graphite cushion block, placing another graphite cushion block on the mould, pressing a two-hand switch (4) after placing the mould, pressing the graphite cushion block and the mould tightly, inserting a thermocouple into a temperature measuring hole on the mould, and closing a furnace door;

sixthly, vacuumizing: confirming that the air release valve is in a closed state, opening a vacuum meter (16), and then vacuumizing until the vacuum degree reaches 10^-2Or lower, proceeding to the next step;

setting a temperature control meter, setting a heating program: setting a temperature rise curve, dividing the temperature rise curve into two stages of slow temperature rise and fast temperature rise, finally raising the temperature to 900 ℃, and preserving the temperature for 30 min;

setting data acquisition software: opening related software on a control computer, and recording data such as temperature, voltage, current and the like in the sintering process;

ninthly, sintering: setting a heating mode as automatic heating, turning on a sintering power supply and starting automatic heating;

and c, closing vacuum after sintering is finished, and taking out a sample: closing a sintering power switch (20), unloading pressure, stopping data software acquisition, storing a data curve, cooling for half an hour, closing vacuum and taking out a sample when the temperature of the mould is lower than 150 ℃;

⑪ shut down instrument: and closing the furnace chamber, vacuumizing, and then sequentially closing power supplies of all parts of the sintering furnace.

And step S5, the method further comprises the steps of slightly shaking the beaker to promote the potassium carbonate to be dissolved in the water, stopping heating after 10min, continuously soaking the sample in the water, and standing for 24 h.

The invention also provides a porous titanium-aluminum alloy prepared by the method based on the high-frequency pulse current sintering.

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

according to the porous titanium-aluminum alloy prepared based on high-frequency pulse current sintering and the preparation method thereof, provided by the invention, the Ti-Al alloy porous material is prepared by using potassium carbonate particles as a pore-forming agent, and the purpose of physical pore-forming is realized by utilizing the solubility difference of potassium carbonate in water and ethanol. By high frequency pulse current sintering, samples can be prepared at a very fast sintering rate. The pore size of the sample can be adjusted by adjusting the pore size of the potassium carbonate particles, and the maximum porosity can be obtained. And (3) carrying out heat treatment on the sample after sintering to ensure that unreacted titanium and aluminum particles can completely carry out diffusion reaction to obtain the uniform Ti-Al alloy porous material.

Drawings

FIG. 1 is a diagram of an entire machine of a spark plasma sintering apparatus;

FIG. 2 is a control panel of the spark plasma sintering apparatus;

FIG. 3 is a schematic diagram of a high-frequency current pulse sintering;

FIG. 4 is a view showing the structure of a micropore of a sample (magnification: 3000 times)

FIG. 5 is a diagram showing the structure of the micro-pores of the prepared sample (magnification: 2000).

In the figure: 1. a cooling system, 2, an up/down conversion switch, 3, a cavity pressure gauge, 4, a two-hand switch, 5, a sintering operation and control unit, 6, a record analysis unit, 7, a vacuum pump, 8, a switch box, 9, a temperature control gauge, 10, an SPS ammeter, 11, an SPS voltmeter, 12, a Z-axis displacement display, 13, a buzzer/alarm reset button, 14, a pressure gauge, 15, a manual pressure control knob, 16, a vacuum gauge, 17, a vacuum gauge switch, 18, an automatic/manual mode conversion, 19, a control cabinet power switch, 20, a sintering power switch, 21, a temperature/pressure controller conversion, 22, a Z-axis controller, 23, a current manual adjusting knob, 24, an alarm indicator lamp, 25, a diffusion pump switch, 26, a three-way valve converter, 27, a pressure controller, 28, a pressure automatic/manual mode conversion, 29. temperature/pressure controller switching, 30, vacuum pump switch, 31, control main valve, 32, emergency switch, 33, vacuum chamber, 34, upper ram electrode, 35, upper ram, 36, lower ram electrode, 100, sample powder.

Detailed Description

The chemical materials used in this example were: potassium carbonate powder, aluminum powder, titanium powder and ethanol, wherein the combined preparation dosage is as follows:

potassium carbonate powder: k₂CO₃80 mesh

6061 aluminum alloy powder: al 300 mesh

Titanium powder: ti 325 mesh

Ethanol: CH (CH)₃CH₂OH。

The preparation method comprises the following steps:

(1) preparation of the Mixed powder

According to the mass ratio of 1:2, titanium powder and aluminum powder are weighed by an electronic balance and are subjected to low-speed ball milling and mixing, wherein the rotating speed is 250 r/min.

(2) Surface-coated mixed powder of potassium carbonate

Wetting potassium carbonate particles: pouring potassium carbonate powder into a small beaker, adding ethanol into the small beaker, and uniformly stirring the mixture by using a glass rod;

filtering: filtering the potassium carbonate particles from the ethanol by using a 80-mesh wire mesh;

coating binary mixed powder: quickly putting the potassium carbonate powder particles with wet surfaces obtained after filtration into Ti-Al mixed powder, so that the surfaces of the potassium carbonate particles are coated with a layer of titanium and aluminum particles;

sieving: and screening the obtained mixed powder by using a fine screen to remove redundant titanium powder and aluminum powder to obtain uniform potassium carbonate particles with surfaces coated with binary mixed powder.

(3) Sintering

Sintering the mixed powder by using high-frequency pulse current:

checking in an early stage: checking whether the oil level of the vacuum pump 7 is normal or not, whether the cooling system 1 is normal or not, and whether the manual pressure control knob 15 and the manual current adjusting knob 23 return to zero or not;

starting up: turning on a main power switch, cooling the power of the system 1, pressing down a water pump and a refrigeration knob, turning on a power switch 19 of the control cabinet, and turning on a computer;

opening the furnace chamber: closing the vacuum gauge 16 and opening the oven door;

assembling the die: filling a piece of graphite paper below the die, pouring the weighed sample powder into the die cavity, covering a layer of graphite paper on the upper surface after compaction, putting the upper pressure head 35, and rotating the upper pressure head 35 back and forth for several circles to uniformly distribute the powder in the die cavity;

putting the mold into the furnace chamber, closing the furnace chamber: placing a mould in the center of a graphite cushion block, padding a piece of graphite paper between the mould and the graphite cushion block, placing another graphite cushion block on the mould, pressing a two-hand switch 4 after placing the mould, pressing the graphite cushion block and the mould tightly, inserting a thermocouple into a temperature measuring hole on the mould, and closing a furnace door;

sixthly, vacuumizing: confirming that the air release valve is in a closed state, opening the vacuum meter 16, and then vacuumizing until the vacuum degree reaches 10^-2Or lowerThen, the next step is carried out;

setting a temperature control meter, setting a heating program: setting a temperature rise curve, dividing the temperature rise curve into two stages of slow temperature rise and fast temperature rise, finally raising the temperature to 900 ℃, and preserving the temperature for 30 min;

setting data acquisition software: opening related software on a control computer, and recording data such as temperature, voltage, current and the like in the sintering process;

ninthly, sintering: setting a heating mode as automatic heating, turning on a sintering power supply and starting automatic heating;

and c, closing vacuum after sintering is finished, and taking out a sample: and closing the sintering power switch 20, unloading the pressure, stopping data software acquisition and storing a data curve. After the temperature is reduced for half an hour and the temperature of the mould is lower than 150 ℃, closing the vacuum and taking out the sample;

⑪ shut down instrument: and closing the furnace chamber, vacuumizing, and then sequentially closing power supplies of all parts of the sintering furnace.

(4) Polishing treatment

Polishing a disc-shaped sample obtained by sintering the high-frequency pulse current by using silicon carbide abrasive paper with the roughness of 400, completely removing graphite adhered to the upper surface, the lower surface and the circumferential side surface of the disc-shaped sample, keeping the surface clean and ensuring that the surface is provided with open holes connected with the inside of the sample.

(5) Forming holes

Putting a sample with a good open pore structure on the surface into a small beaker, and adding a certain amount of clear water into the small beaker to ensure that the sample is completely immersed in water;

secondly, heating the small beaker, and slightly shaking the beaker to promote the potassium carbonate to be dissolved in the water;

③ stopping heating after 10min, continuously soaking the sample in water, and standing for 24 h;

and fourthly, taking out the sample from the beaker, washing the sample with clear water, and drying the sample to obtain the titanium-aluminum porous alloy material with open pores.

(6) Thermal treatment

And (3) putting the sample without the potassium carbonate pore-forming agent into a tubular heating furnace for heat treatment, heating and preserving heat for a period of time to ensure that titanium and aluminum particles can fully perform diffusion reaction to obtain the uniform titanium-aluminum binary alloy.

(7) Detection, analysis, characterization

Analyzing and characterizing micropores of the prepared porous titanium-aluminum alloy material;

the microstructure of the material was analyzed with a scanning electron microscope.

As can be seen from fig. 4 and 5, the communicated pores are formed in the material, the size of the pores is relatively uniform, the pore wall is well combined, and the components are uniformly distributed.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, or direct or indirect applications in other related fields, which are made by the contents of the present specification, are included in the scope of the present invention.