Method for preparing SrTiO3 ceramic material based on GO-assisted low-temperature flash burning technology

Abstract

The invention discloses a method for preparing a SrTiO3 ceramic material based on a GO-assisted low-temperature flash sintering technology. The method comprises the following steps: pre-sintering and grinding SrCO3 and TiO2 serving as raw materials to obtain SrTiO3 powder; mixing the prepared SrTiO3 powder with 2.5-5wt% of GO for ball milling, then drying and sieving to obtain mixed powder, pressing the mixed powder, placing the obtained ceramic green body at the positive and negative ends of a platinum wire electrode in a furnace body, heating at the speed of 10-20 DEG C / min, applying an electric field at the electric field intensity of 250-500V / cm and the current density of 25-50mA / mm < 2 > at the temperature of 100-200 DEG C, and immediately performing flash burning to obtain the SrTiO3 / GO composite material. And turning off the power supply and the electric furnace after the flash burning lasts for 30-120 seconds to obtain the SrTiO3 ceramic material. The GO is added into the SrTiO3 ceramic, so that the conductivity of a sample is improved, the preparation of the SrTiO3 ceramic at low temperature is realized, the energy consumption is reduced, and a feasible scheme is provided for green and efficient ceramic preparation.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional materials and relates to a method for preparing SrTiO3 ceramic materials, and specifically relates to a method for preparing SrTiO3 ceramic materials based on GO-assisted low-temperature flash sintering technology. Background Art

[0002] Strontium titanate (SrTiO3), a typical perovskite-type functional ceramic, is widely used in multilayer ceramic capacitors, positive temperature coefficient thermistors, and microwave tuning devices due to its high room temperature dielectric constant, low loss, and tunable ferroelectric and quantum paraelectric behavior. With the surge in demand for miniaturized and high-frequency electronic components in industries such as 5G communications and new energy electric vehicles, higher requirements are being placed on the efficient preparation of SrTiO3 ceramics. Furthermore, SrTiO3, due to its standard and simple perovskite structure, has become a typical template material for understanding defect chemistry and improving material properties. However, the high sintering temperature of SrTiO3 ceramics limits its manufacturing and use in low-carbon and energy-saving applications.

[0003] Sintering is a crucial step in the ceramic production process. Traditionally, SrCO₃ and TiO₂ are ball-milled together, followed by a 2-4-hour heat preservation at 1350-1500°C for a solid-state reaction and densification. Driven by the pursuit of energy conservation, economical efficiency, and environmental friendliness, the production of ceramics at lower temperatures and in shorter timeframes has long been a goal for researchers in the field of materials engineering. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for preparing SrTiO3 ceramic materials based on GO-assisted low-temperature flash sintering technology, so as to realize the preparation of SrTiO3 ceramics at low temperature, reduce energy consumption, and provide a feasible solution for the green and efficient preparation of ceramics.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing SrTiO3 ceramic material based on GO-assisted low-temperature flash sintering technology comprises the following steps:

[0007] Step 1: SrCO3 and TiO2 are mixed in a molar ratio of 1:1, ball-milled, dried, pressed into a green body, pre-sintered, and ground to obtain SrTiO3 powder;

[0008] Step 2: The SrTiO3 powder prepared in step 1 is mixed with 2.5-5wt% GO and ball-milled, followed by drying and sieving to obtain a mixed powder. The mixed powder is then pressed and the obtained ceramic green body is placed at the positive and negative ends of the platinum wire electrode in the furnace body. The furnace temperature is set to rise at a rate of 10-20℃ / min, the electric field strength is 250-500V / cm, and the current density is 25-50mA / mm 2 When the temperature is 100-200℃, an electric field is applied, and flash burning occurs immediately. After the flash burning lasts for 30-120s, the power supply and the electric furnace are turned off to obtain SrTiO3 ceramic material.

[0009] The present invention also has the following technical features:

[0010] Preferably, the ball milling in step 1 and step 2 is performed by mixing the raw materials, zirconia balls and deionized water in a mass ratio of 1:5:1 and milling for 10 to 12 hours.

[0011] Preferably, the drying in step 1 and step 2 is performed by placing the product in an oven at 80° C. for 12 to 24 hours.

[0012] Preferably, the pre-sintering condition in step 1 is to place the green body in a tube furnace, heat it to 1100-1200° C. in an air atmosphere and keep it at that temperature for 2-4 hours, and then naturally cool it to room temperature in the furnace.

[0013] Preferably, the sieving in step 2 is through a 120-200 mesh sieve.

[0014] Preferably, the pressing in step 2 is to pour the mixed powder into a mold, press it into shape, and then demould it, and cold isostatically press the demoulded green body at a pressure of 200-250 MPa for 3-5 minutes.

[0015] Compared with the prior art, the present invention has the following technical effects:

[0016] The present invention adds GO to SrTiO3 ceramics. GO improves the electrical conductivity of the sample, enabling the preparation of SrTiO3 ceramics at low temperatures. The low-temperature sintering conditions of 100-200°C and 30-120s significantly reduce energy consumption compared to the sintering conditions of 1450-1500°C and 2-4h of traditional SrTiO3 ceramics, providing a feasible solution for the green and efficient preparation of ceramics. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 XRD patterns of the ceramic samples prepared in Example 1 and Comparative Example 1;

[0018] Figure 2 Digital photos of the flash firing process of the ceramic samples of Example 1 and Comparative Example 1;

[0019] Figure 3 Graph showing the electric field intensity and current density changing with furnace temperature during the flash firing process of the ceramic samples of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0020] The specific contents of the present invention are further explained in detail below with reference to the embodiments.

[0021] GO used in the following examples refers to graphene oxide.

[0022] Example 1

[0023] This embodiment provides a method for preparing SrTiO3 ceramic material based on GO-assisted low-temperature flash sintering technology, comprising the following steps:

[0024] Step 1: Take SrCO3 and TiO2 in a molar ratio of 1:1, mix them, and then ball mill them for 10 hours according to the mass ratio of raw materials, zirconia balls, and deionized water in a ratio of 1:5:1. Then place them in an oven and dry them at 80°C for 12 hours, then press them into a blank. Place the blank in a tube furnace and heat it to 1100°C in an air atmosphere for 4 hours. After completion, naturally cool it to room temperature in the furnace and grind it to obtain SrTiO3 powder.

[0025] Step 2: Mix the SrTiO3 powder prepared in step 1 with 3wt% GO, and ball-mill the mixture for 10 hours according to the mass ratio of raw materials, zirconia balls and deionized water of 1:5:1. Then, place it in an oven and dry it at 80°C for 12 hours, and pass it through a 200-mesh sieve to obtain a mixed powder. Pour the mixed powder into a mold, press it into shape, and demold it. The demolded body is cold isostatically pressed at a pressure of 200 MPa for 5 minutes. The obtained ceramic green body is placed at the positive and negative ends of the platinum wire electrode in the furnace body, and the furnace temperature is set to rise at a rate of 10°C / min, the electric field strength is 300V / cm, and the current density is 30mA / mm 2 When the temperature is 115℃, an electric field is applied and flash occurs. After the flash lasts for 115s, the power supply and the electric furnace are turned off to obtain SrTiO3 ceramic material.

[0026] Example 2

[0027] This embodiment provides a method for preparing SrTiO3 ceramic material based on GO-assisted low-temperature flash sintering technology, comprising the following steps:

[0028] Step 1: Take SrCO3 and TiO2 in a molar ratio of 1:1, mix them, and then ball mill them for 11 hours according to the mass ratio of raw materials, zirconia balls, and deionized water in a ratio of 1:5:1. Then place them in an oven and dry them at 80°C for 15 hours, then press them into a blank. Place the blank in a tube furnace and heat it to 1150°C in an air atmosphere for 3 hours. After completion, naturally cool it to room temperature in the furnace and grind it to obtain SrTiO3 powder.

[0029] Step 2: Mix the SrTiO3 powder prepared in step 1 with 2.5wt% GO, and ball-mill the mixture for 11 hours according to the mass ratio of raw materials, zirconia balls and deionized water of 1:5:1. Then, place it in an oven and dry it at 80°C for 15 hours, and pass it through a 150-mesh sieve to obtain a mixed powder. Pour the mixed powder into a mold and press it into shape, then demold it. The demolded body is cold isostatically pressed at a pressure of 220MPa for 4 minutes. The obtained ceramic green body is placed at both ends of the positive and negative poles of the platinum wire electrode in the furnace body, and the furnace temperature is set to rise at a rate of 15°C / min, the electric field strength is 250V / cm, and the current density is 50mA / mm 2 When the temperature is 100℃, an electric field is applied and flash burning occurs. After the flash burning lasts for 120s, the power supply and the electric furnace are turned off to obtain SrTiO3 ceramic material.

[0030] Example 3

[0031] This embodiment provides a method for preparing SrTiO3 ceramic material based on GO-assisted low-temperature flash sintering technology, comprising the following steps:

[0032] Step 1: Take SrCO3 and TiO2 in a molar ratio of 1:1, mix them, and then ball-mill for 12 hours according to the mass ratio of raw materials, zirconia balls, and deionized water in a ratio of 1:5:1. Then place them in an oven and dry them at 80°C for 24 hours, then press them into a blank. Place the blank in a tube furnace and heat it to 1200°C in an air atmosphere for 2 hours. After completion, naturally cool it to room temperature in the furnace and grind it to obtain SrTiO3 powder.

[0033] Step 2: Mix the SrTiO3 powder prepared in step 1 with 5wt% GO, and ball-mill the mixture for 12 hours according to the mass ratio of raw materials, zirconia balls and deionized water of 1:5:1. Then, place it in an oven and dry it at 80°C for 24 hours, and pass it through a 120-mesh sieve to obtain a mixed powder. Pour the mixed powder into a mold and press it into shape, then demold it. The demolded body is cold isostatically pressed at a pressure of 250MPa for 3 minutes. The obtained ceramic green body is placed at the positive and negative ends of the platinum wire electrode in the furnace body, and the furnace temperature is set to rise at a rate of 20°C / min, the electric field strength is 500V / cm, and the current density is 25mA / mm 2When the temperature is 100℃, an electric field is applied and flash burning occurs. After the flash burning lasts for 120s, the power supply and the electric furnace are turned off to obtain SrTiO3 ceramic material.

[0034] Example 4

[0035] This embodiment provides a method for preparing SrTiO3 ceramic material based on GO-assisted low-temperature flash sintering technology, comprising the following steps:

[0036] Step 1: Take SrCO3 and TiO2 in a molar ratio of 1:1, mix them, and then ball mill them for 10 hours according to the mass ratio of raw materials, zirconia balls, and deionized water in a ratio of 1:5:1. Then place them in an oven and dry them at 80°C for 12 hours, then press them into a blank. Place the blank in a tube furnace and heat it to 1100°C in an air atmosphere for 4 hours. After completion, naturally cool it to room temperature in the furnace and grind it to obtain SrTiO3 powder.

[0037] Step 2: Mix the SrTiO3 powder prepared in step 1 with 3wt% GO, and ball-mill the mixture for 10 hours according to the mass ratio of raw materials, zirconia balls and deionized water of 1:5:1. Then, place it in an oven and dry it at 80°C for 12 hours, and pass it through a 200-mesh sieve to obtain a mixed powder. Pour the mixed powder into a mold, press it into shape, and demold it. The demolded body is cold isostatically pressed at a pressure of 200 MPa for 5 minutes. The obtained ceramic green body is placed at the positive and negative ends of the platinum wire electrode in the furnace body, and the furnace temperature is set to rise at a rate of 10°C / min, the electric field strength is 300V / cm, and the current density is 30mA / mm 2 When the temperature is 200℃, an electric field is applied and flash occurs. After the flash lasts for 30s, the power supply and the electric furnace are turned off to obtain SrTiO3 ceramic material.

[0038] Comparative Example 1

[0039] This embodiment provides a method for preparing SrTiO3 ceramic material based on GO-assisted low-temperature flash sintering technology, comprising the following steps:

[0040] Step 1: SrCO3 and TiO2 are taken in a molar ratio of 1:1, mixed, and ball-milled for 10 hours according to a mass ratio of raw materials, zirconia balls, and deionized water of 1:5:1, and then placed in an oven and dried at 80°C for 12 hours, pressed into an embryonic body, and pre-fired, and then ground with a grinder to obtain SrTiO3 powder;

[0041] Step 2: Mix the SrTiO3 powder prepared in step 1 with 0wt% GO, and ball-mill the mixture for 10 hours according to the mass ratio of raw materials, zirconia balls and deionized water of 1:5:1. Then, place it in an oven and dry it at 80°C for 12 hours, and pass it through a 120-mesh sieve to obtain a mixed powder. Pour the mixed powder into a mold, press it into shape, and demold it. The demolded body is cold isostatically pressed at a pressure of 200MPa for 5 minutes. The obtained ceramic green body is placed at the positive and negative ends of the platinum wire electrode in the furnace body, and the furnace temperature is set to rise at a rate of 10°C / min, the electric field strength is 300V / cm, and the current density is 30mA / mm 2 When the temperature is 115℃, an electric field is applied and flash occurs. After the flash lasts for 115s, the power supply and the electric furnace are turned off to obtain SrTiO3 ceramic material.

[0042] Figure 1 The XRD patterns of the ceramic samples prepared in Example 1 and Comparative Example 1 are as follows: Figure 1 It can be seen that the XRD diffraction peaks of the samples of Example 1 and Comparative Example 1 both show a typical perovskite structure, corresponding to cubic phase SrTiO3. GO volatilizes during the flash burning process of the sample of Example 1, and the finally prepared ceramic material contains only cubic phase SrTiO3 components.

[0043] Figure 2 Digital photos of the flash firing process of ceramic samples of Example 1 and Comparative Example 1; Figure 2 It can be seen that before the flash started, the samples in the tube furnace showed no obvious signs of luminescence. When flash occurred, the samples glowed significantly, and this strong luminescence state lasted until the electric field was turned off; and in the experiments of Example 1 and Comparative Example 1, the luminescence intensity of the positive and negative electrodes remained quite uniform, indicating that the contact between the electrodes and the platinum wire was good, which provided a guarantee for the smooth progress of the flash experiment. At the same time, the occurrence of the luminescence phenomenon also proves that the SrTiO3-0.0wt% GO (876℃) and SrTiO3-3wt% GO (115℃) samples successfully flashed under the combined action of the electric field and temperature field.

[0044] Figure 3 Graph showing the electric field intensity and current density changing with furnace temperature during the flash firing process of the ceramic samples of Example 1 and Comparative Example 1.

[0045] For SrTiO3-0.0wt%GO, SrTiO3-3.0wt%GO, the electric field strength (300V / cm) and the current density (30mA / mm 2 ) parameters. Figure 3It can be seen that when the sample flashes, the power supply changes from voltage control to current control, indicating that both SrTiO3-0.0wt% GO and SrTiO3-3.0wt% GO samples can flash. The ceramic sample with GO added improves the conductivity of the sample, reducing the starting temperature to below 115°C, while the ceramic sample without GO adds flashes above 850°C.

[0046] The present invention adds GO to SrTiO3 ceramics. GO improves the electrical conductivity of the sample, enabling the preparation of SrTiO3 ceramics at low temperatures. The low-temperature sintering conditions of 100-200°C and 30-120s significantly reduce energy consumption compared to the sintering conditions of 1450-1500°C and 2-4h of traditional SrTiO3 ceramics, providing a feasible solution for the green and efficient preparation of ceramics.

Claims

1. A method for preparing SrTiO3 ceramic material based on GO-assisted low-temperature flash sintering technology, characterized in that: The following steps are involved: Step 1: SrCO3 and TiO2 are mixed in a molar ratio of 1:1, ball-milled, dried, pressed into a green body, pre-sintered, and ground to obtain SrTiO3 powder; Step 2: The SrTiO3 powder prepared in step 1 is mixed with 2.5-5wt% GO and ball-milled, followed by drying and sieving to obtain a mixed powder. The mixed powder is then pressed and the obtained ceramic green body is placed at the positive and negative ends of the platinum wire electrode in the furnace body. The furnace temperature is set to rise at a rate of 10-20℃ / min, the electric field strength is 250-500V / cm, and the current density is 25-50mA / mm 2 When the temperature is 100-200℃, an electric field is applied, and flash burning occurs immediately. After the flash burning lasts for 30-120s, the power supply and the electric furnace are turned off to obtain SrTiO3 ceramic material.

2. The method for preparing SrTiO3 ceramic material based on GO-assisted low-temperature flash sintering technology according to claim 1, characterized in that: The ball milling in step 1 and step 2 is performed by mixing the raw materials, zirconia balls and deionized water in a mass ratio of 1:5:1 and milling for 10 to 12 hours.

3. The method for preparing SrTiO3 ceramic material based on GO-assisted low-temperature flash sintering technology according to claim 1, characterized in that: The drying in step 1 and step 2 is performed by placing the product in an oven at 80° C. for 12 to 24 hours.

4. The method for preparing SrTiO3 ceramic material based on GO-assisted low-temperature flash sintering technology according to claim 1, characterized in that: The pre-firing conditions described in step 1 are to place the green body in a tubular furnace, heat it to 1100-1200°C in an air atmosphere and keep it at that temperature for 2-4 hours, and then naturally cool it to room temperature in the furnace.

5. The method for preparing SrTiO3 ceramic material based on GO-assisted low-temperature flash sintering technology according to claim 1, characterized in that: The sieving in step 2 is through a 120-200 mesh sieve.

6. The method for preparing SrTiO3 ceramic material based on GO-assisted low-temperature flash sintering technology according to claim 1, characterized in that: The pressing in step 2 is to pour the mixed powder into a mold, press it into shape, and then demould it, and then cold isostatically press the demoulded green body at a pressure of 200-250 MPa for 3-5 minutes.

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