CN109734445A - A kind of electric field-assisted flash sintering method of Ultra-fine Grained hafnium oxide ceramics - Google Patents
A kind of electric field-assisted flash sintering method of Ultra-fine Grained hafnium oxide ceramics Download PDFInfo
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Abstract
The present invention provides a kind of electric field-assisted flash sintering method of Ultra-fine Grained hafnium oxide ceramics, which comprises the steps of: 1) weighs HfO2Powder is pressed into green body;2) electric field-assisted sintering equipment is provided;3) sample is put between the top electrode of electric field-assisted agglomerating plant and lower electrode, after so that sample temperature is risen to 800-1300 DEG C using at least two radiant heating heaters, initially enters holding stage;4) voltage at sample both ends is increased several times while entering holding stage, is then shut off sample both end voltage and radiant heating apparatus, makes sample cooled to room temperature to get ceramic to the Ultra-fine Grained hafnium oxide.Present invention application DC electric field assisted sintering technology, quickly prepares hafnium oxide ceramics, and the hafnium oxide ceramic material of consistency height, homogeneous grain size is obtained by process conditions such as regulation threshold temperature, field strength, electric currents.
Description
Technical field
The present invention relates to a kind of electric field-assisted flash sintering methods of Ultra-fine Grained hafnium oxide ceramics.
Background technique
Hafnium oxide (HfO2) it is Group IVB oxide, fusing point is 2800 DEG C, and thermal capacitance is 271kcal/mol, can be used as high temperature
Refractory material.Hafnium oxide (HfO2) as a kind of oxide ceramic material with broad-band gap and high dielectric constant, film
Because having high rigidity, high chemical stability and excellent dielectric properties, especially HfO2Manufactured optical thin film has high rigidity,
High refractive index, high-strength laser damage threshold and good through performance of the near ultraviolet to middle infrared band the features such as are high in preparation
Important application is suffered from terms of performance device and superlaser.Under high pressure, HfO2Have higher elastomer modulus and
Intensity is considered as the optional object of superhard material.HfO simultaneously2Also there is very big neutron cross-section face absorption coefficient (> 150cm2/
atom×1024), nuclear reaction can be efficiently controlled.In addition, when being used in mixed way with other oxides, it is also possible to make catalyst, protection
Coating and artificial gem.
However, but few people are related to the research in terms of the preparation to hafnium oxide ceramics.Due to hafnium oxide fusing point
Height if not only energy consumption is high, the time is long using traditional sintering method, but also is difficult to make its densification.And select the two of nano-scale
Hafnium oxide powder is sintered, although its high specific surface area can reduce sintering temperature to a certain degree, exists simultaneously crystal grain
The problem of excessively growing up.It solves the above problems so needing to explore a kind of suitable sintering processing.
Summary of the invention
The present invention provides a kind of electric field-assisted Fast Sintering of Ultra-fine Grained hafnium oxide ceramics to solve above-mentioned technical problem
Method.This method can obtain the hafnium oxide ceramic material that consistency is high, crystallite dimension is small, and sintering process cleaning, section
Energy.
To achieve the goals above, technical scheme is as follows:
A kind of electric field-assisted flash sintering method of Ultra-fine Grained hafnium oxide ceramics, includes the following steps:
1) HfO is weighed2Powder is pressed into green body at 100-200MPa;
2) electric field-assisted sintering equipment is provided, the electric field-assisted sintering equipment includes electric field-assisted agglomerating plant and radiation
Heating equipment;The electric field-assisted agglomerating plant includes top electrode and lower electrode, and sample is set to the top electrode and lower electrode
Between, the radiant heating apparatus includes at least two radiant heating heaters, and at least two radiant heatings heater is set
The two sides of sample are placed in, electric current carries out electric current heating to sample by top electrode and lower electrode;
3) sample is put between the top electrode of electric field-assisted agglomerating plant and lower electrode, utilizes at least two radiant heatings
After heater makes sample temperature rise to 800-1300 DEG C, holding stage is initially entered;
4) sample both end voltage is increased to 180-220V, heat-insulation pressure keeping 8-15min while entering holding stage, then will
Voltage is increased to 230-270V, heat-insulation pressure keeping 8-15min, continues to bring the voltage up to 280-300V, heat-insulation pressure keeping 8-15min,
Voltage is finally risen into 320V-360V, control cutoff current value is closed in 1-5A and after maintaining 60-180s after rising to 320V-360V
Sample both end voltage and radiant heating apparatus are closed, sample cooled to room temperature is made to make pottery to get to the Ultra-fine Grained hafnium oxide
Porcelain.
In above scheme, guarantee that maximum field strength is less than 800V/cm during voltage is raised in the step 4).
In above scheme, the top electrode and lower electrode are Si-Mo rod electrode.
In above scheme, each radiant heating fever volume morphing is cylinder-shaped or square tube shape.
In above scheme, at least two radiant heatings heater is dispersed in around sample.
In above scheme, the radiant heating heater is graphite using material.
In above scheme, HfO in step 1)2The purity of powder is greater than 99%.
In above scheme, HfO in step 1)2Powder is in monoclinic phase.
In above scheme, HfO in step 1)2The average particle diameter size 30-100nm of powder.
In above scheme, the diameter of phi 10-50mm of green body in step 1).
Compared with prior art, the present invention has the following advantages: solving hafnium oxide pottery using electric field-assisted sintering
Porcelain is difficult to the problem of with conventional sintering mode densified sintering product.And the application of DC electric field improves powder electric conductivity, to form electricity
The feedback loop of stream causes the melting of crystal boundary avalanche type, accelerates atom diffusion, completes densification process.It can not only make titanium dioxide
Hafnium ceramic is fast densified, and can largely inhibit the growth of crystal grain, is conducive to the preparation of nano ceramics.And
This method is efficient, cleans, energy conservation.Therefore, present invention application DC electric field assisted sintering technology carries out hafnium oxide ceramics fast
Speed preparation, and high, homogeneous grain size the dioxy by the process conditions acquisition consistency such as regulation threshold temperature, field strength, electric current
Change hafnium ceramic material.
Detailed description of the invention
Fig. 1 is to realize electric field-assisted sintering equipment of the invention.
Fig. 2 be embodiment 2 experiment condition under hafnium oxide ceramics obtained SEM figure.
In figure: 1- electrode;2- sample;3- radiant heating heater.
Specific embodiment
Embodiment 1
Weigh the HfO of 1.4g2Powder is pressed into the green body of Φ 10mm, thickness 4.5mm at 100MPa, sample is put into
Between two Si-Mo rod electrodes, starts to heat to sample using the radiant heating heater of radiant heating apparatus, rise to 800 DEG C
Afterwards, holding stage is initially entered, while the voltage at sample both ends is added into 200V (field strength is about 444.4V/cm), heat-insulation pressure keeping
10min, then voltage is added to 250V (field strength is about 555.6V/cm), after heat-insulation pressure keeping 10min, voltage rises to 300V, and (field strength is about
For 666.7V/cm), after heat-insulation pressure keeping 10min, voltage is risen to 360V (field strength is about 800V/cm), and current value control is 5A, dimension
Sample both end voltage and Muffle furnace power supply are closed after holding 60s, makes sample cooled to room temperature.Gained sample it is relatively compact
Degree: 94.3% crystallite dimension: 0.32-1.19 μm.
Embodiment 2
Weigh the HfO of 30.5g2Powder is pressed into the green body of Φ 50mm, thickness 4.0mm at 200MPa, sample is put into
Between two Si-Mo rod electrodes, starts to heat to sample using the radiant heating heater of radiant heating apparatus, rise to 1300 DEG C
Afterwards, holding stage is initially entered, while the voltage at sample both ends is added into 200V (field strength is about 500.0V/cm), heat-insulation pressure keeping
10min, then voltage is added to 250V (field strength is about 625.0V/cm), after heat-insulation pressure keeping 10min, voltage rises to 300V, and (field strength is about
For 750.0V/cm), after heat-insulation pressure keeping 10min, voltage is risen to 320V (field strength is about 800.0V/cm), and current value control is 1A,
Sample both end voltage and Muffle furnace power supply are closed after maintaining 180s, makes sample cooled to room temperature.The opposite cause of gained sample
Density: 95.9% crystallite dimension: 0.17-0.96 μm.
The above is only preferred embodiments of the invention, not does limitation in any form to the present invention, all
According to the technical essence of the invention to any simple modification, equivalent change and modification made by above example, this hair is still fallen within
In the range of bright technical solution.
Claims (10)
1. a kind of electric field-assisted flash sintering method of Ultra-fine Grained hafnium oxide ceramics, which comprises the steps of:
1) HfO is weighed2Powder is pressed into green body at 100-200MPa;
2) electric field-assisted sintering equipment is provided, the electric field-assisted sintering equipment includes electric field-assisted agglomerating plant and radiant heating
Equipment;The electric field-assisted agglomerating plant includes top electrode and lower electrode, and sample is set between the top electrode and lower electrode,
The radiant heating apparatus includes at least two radiant heating heaters, and at least two radiant heatings heater is set to sample
The two sides of product, electric current carry out electric current heating to sample by top electrode and lower electrode;
3) sample is put between the top electrode of electric field-assisted agglomerating plant and lower electrode, is generated heat using at least two radiant heatings
After body makes sample temperature rise to 800-1300 DEG C, holding stage is initially entered;
4) sample both end voltage is increased to 180-220V, heat-insulation pressure keeping 8-15min while entering holding stage, then by voltage
It is increased to 230-270V, heat-insulation pressure keeping 8-15min, is continued to bring the voltage up to 280-300V, heat-insulation pressure keeping 8-15min, finally
Voltage is risen into 320V-360V, control cutoff current value closes sample after 1-5A and maintenance 60-180s after rising to 320V-360V
Product both end voltage and radiant heating apparatus make sample cooled to room temperature to get ceramic to the Ultra-fine Grained hafnium oxide.
2. the electric field-assisted flash sintering method of Ultra-fine Grained hafnium oxide ceramics as described in claim 1, which is characterized in that institute
It states the raised maximum field strength of guarantee in the process of voltage in step 4) and is less than 800V/cm.
3. the electric field-assisted flash sintering method of Ultra-fine Grained hafnium oxide ceramics as described in claim 1, which is characterized in that institute
It states top electrode and lower electrode is Si-Mo rod electrode.
4. the electric field-assisted flash sintering method of Ultra-fine Grained hafnium oxide ceramics as described in claim 1, which is characterized in that institute
Stating each radiant heating fever volume morphing is cylinder-shaped or square tube shape.
5. the electric field-assisted flash sintering method of Ultra-fine Grained hafnium oxide ceramics as described in claim 1, which is characterized in that institute
At least two radiant heating heaters are stated to be dispersed in around sample.
6. the electric field-assisted flash sintering method of Ultra-fine Grained hafnium oxide ceramics as described in claim 1, which is characterized in that institute
It is graphite that radiant heating heater, which is stated, using material.
7. the electric field-assisted flash sintering method of Ultra-fine Grained hafnium oxide ceramics as described in claim 1, which is characterized in that step
It is rapid 1) in HfO2The purity of powder is greater than 99%.
8. the electric field-assisted flash sintering method of Ultra-fine Grained hafnium oxide ceramics as described in claim 1, which is characterized in that step
It is rapid 1) in HfO2Powder is in monoclinic phase.
9. the electric field-assisted flash sintering method of Ultra-fine Grained hafnium oxide ceramics as described in claim 1, which is characterized in that step
It is rapid 1) in HfO2The average particle diameter size 30-100nm of powder.
10. the electric field-assisted flash sintering method of Ultra-fine Grained hafnium oxide ceramics as described in claim 1, which is characterized in that
The diameter of phi 10-50mm of green body in step 1).
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CN110451990A (en) * | 2019-09-06 | 2019-11-15 | 西北工业大学 | A kind of method that Fast Sintering prepares metal oxide texture ceramic material under room temperature |
CN111947460A (en) * | 2020-08-03 | 2020-11-17 | 宝钢化工湛江有限公司 | Control method of heating furnace for blast furnace gas and coke oven gas mixed combustion |
CN111981847A (en) * | 2020-07-24 | 2020-11-24 | 北京科技大学 | Pressure-assisted induction heating vacuum atmosphere flash sintering device |
CN112153764A (en) * | 2020-09-28 | 2020-12-29 | 中国农业大学 | Rapid heating method for preparing ceramic material |
CN113149619A (en) * | 2021-05-14 | 2021-07-23 | 景德镇陶瓷大学 | High-strength low-dielectric-loss alumina ceramic substrate |
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CN112153764A (en) * | 2020-09-28 | 2020-12-29 | 中国农业大学 | Rapid heating method for preparing ceramic material |
CN113149619A (en) * | 2021-05-14 | 2021-07-23 | 景德镇陶瓷大学 | High-strength low-dielectric-loss alumina ceramic substrate |
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