Electric field assisted quick sintering method of ultrafine-grained hafnium oxide ceramic

An electric field-assisted sintering and hafnium dioxide technology, which is applied in the field of electric field-assisted rapid sintering of ultra-fine grain hafnium dioxide ceramics, can solve the problems of long time, few people involved in hafnium dioxide ceramics, and high melting point, so as to improve the powder Conductivity, inhibition of grain growth, and uniform grain size

Inactive Publication Date: 2019-05-10
WUHAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] However, few studies have been done on the preparation of hafnium dioxide ceramics
Due to the high melting point of hafnium dioxide, if the traditional sintering method is used, not only the energy consumption is high, the time is long, but also it is difficult to make it dense
However, nanometer-sized hafnium dioxide powder is selected for sintering. Although its high specific surface area can reduce the sintering temperature to a certain extent, there is also the problem of excessive grain growth.

Method used

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  • Electric field assisted quick sintering method of ultrafine-grained hafnium oxide ceramic

Examples

Experimental program
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Embodiment 1

[0025] Weigh 1.4g of HfO 2 The powder is pressed at 100MPa into a green body with a thickness of Φ10mm and a thickness of 4.5mm. The sample is placed between two silicon-molybdenum rod electrodes, and the radiation heating element of the radiation heating equipment is used to heat the sample. After rising to 800°C, Start to enter the heat preservation stage, and at the same time, increase the voltage at both ends of the sample to 200V (the field strength is about 444.4V / cm), hold the heat for 10 minutes, and then increase the voltage to 250V (the field strength is about 555.6V / cm), heat and hold the pressure After 10 minutes, the voltage rises to 300V (the field strength is about 666.7V / cm), and after 10 minutes of heat preservation and pressure holding, the voltage rises to 360V (the field strength is about 800V / cm), and the current value is controlled to 5A. The terminal voltage and the power supply of the muffle furnace allowed the samples to cool down to room temperature n...

Embodiment 2

[0027] Weigh 30.5g of HfO 2 The powder is pressed at 200MPa into a green body with a diameter of Φ50mm and a thickness of 4.0mm. The sample is placed between two silicon-molybdenum rod electrodes, and the radiation heating element of the radiation heating equipment is used to heat the sample. After rising to 1300°C, Start to enter the heat preservation stage, and at the same time, increase the voltage at both ends of the sample to 200V (the field strength is about 500.0V / cm), hold the heat for 10 minutes, and then increase the voltage to 250V (the field strength is about 625.0V / cm), heat and hold the pressure After 10 minutes, the voltage rises to 300V (the field strength is about 750.0V / cm), after 10 minutes of heat preservation and pressure holding, the voltage rises to 320V (the field strength is about 800.0V / cm), the current value is controlled to 1A, and the sample is turned off after 180s The voltage at both ends and the power supply of the muffle furnace allow the sampl...

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Abstract

The invention provides an electric field assisted quick sintering method of ultrafine-grained hafnium oxide ceramic, which is characterized by comprising the steps of 1) weighing HfO2 powder, and pressing to obtain a blank; 2) providing an electric field assisted sintering device; 3) placing a sample between an upper electrode and lower electrode of the electric field assisted sintering device, heating the sample to 800-1300 DEG C through at least two radiation heaters, and starting to enter a temperature holding phase; 4) upon entry to the temperature holding phase, raising voltages of the two ends of the sample in multiple phases, disabling the voltages of the ends of the sample, and closing the radiation heaters so that the sample naturally cools to room temperature to obtain the ultrafine-grained hafnium oxide ceramic. The direct-current electric field assisted sintering technique is utilized herein to quickly produce hafnium oxide ceramic; the hafnium oxide ceramic with high compactness and uniform grain size is produced by controlling the process conditions, such as threshold temperature, field intensity, and current.

Description

technical field [0001] The invention relates to an electric field-assisted rapid sintering method for ultrafine-grained hafnium dioxide ceramics. Background technique [0002] Hafnium dioxide (HfO 2 ) is a Group IVB oxide with a melting point of 2800°C and a heat capacity of 271kcal / mol, which can be used as a high-temperature refractory material. Hafnium dioxide (HfO 2 ) as an oxide ceramic material with wide band gap and high dielectric constant, its thin film has high hardness, high chemical stability and excellent dielectric properties, especially HfO 2 The prepared optical film has the characteristics of high hardness, high refractive index, high laser damage threshold and good transmission performance in the near-ultraviolet to mid-infrared band, and has important applications in the preparation of high-performance devices and high-energy lasers. Under high pressure conditions, HfO 2 With higher elastic modulus and strength, it is considered as an alternative for s...

Claims

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Application Information

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IPC IPC(8): C04B35/486C04B35/64
Inventor 张帆周楚同张金咏王为民傅正义
Owner WUHAN UNIV OF TECH
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