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Preparation method of porous zinc aluminate ceramics with high wave permeability

A zinc aluminate, high-transparency technology, applied in the field of functional ceramics, can solve problems that affect flight safety, stability and energy saving, high density of zinc aluminate ceramics, increase the weight of aerospace equipment, etc., and achieve good high-temperature mechanical properties , low dielectric constant, low cost effect

Active Publication Date: 2019-04-05
WUHAN INSTITUTE OF TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Most of the zinc aluminate materials prepared in the prior art are dense zinc aluminate ceramics. The dense zinc aluminate ceramics have high dielectric constant, large dielectric loss, small specific surface area, high thermal conductivity, and poor

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0022] Example one

[0023] (1) Mix 1 part of basic zinc carbonate, 10 parts of aluminum ammonium carbonate, 1 part of lithium fluoride, and 1 part of absolute ethanol in parts by weight. The zirconia ball is used as the ball milling medium and ball milled at 400r / min for 5 hours , Put the mixed powder after ball milling into a drying box, and dry the slurry at 50°C for 2 hours. After drying, the slurry is sieved through a 40 mesh screen to obtain a mixed powder.

[0024] (2) After the powder in step (1) is dry-pressed on a tablet press with a pressure of 160 MPa, it is cold isostatically pressed at a pressure of 200 MPa to form a cylindrical sample with a thickness to diameter ratio of 0.6 to obtain Green body.

[0025] (3) Drying and holding the green body at 200°C for 1 hour at a heating rate of 1°C / min, and then sintering and holding at 1450°C for 2 hours at a heating rate of 4°C / min to obtain porous zinc aluminate ceramics.

[0026] After testing, the porous zinc aluminate cera...

Example Embodiment

[0027] Example two

[0028] (1) Mix 4 parts of basic zinc carbonate, 40 parts of aluminum hydroxide, 5 parts of lithium fluoride, and 5 parts of absolute ethanol in parts by weight. The zirconia ball is used as the ball milling medium and ball milled for 10 hours at 1000r / min. , Put the ball-milled mixed powder into a drying box, and dry the slurry at 75°C for 5 hours. After drying, the slurry is sieved through a 30-mesh sieve to obtain a mixed powder.

[0029] (2) After the powder in step (1) is dry-pressed on a tablet press with a pressure of 120 MPa, it is cold isostatically pressed at a pressure of 150 MPa to form a cylindrical sample with a thickness to diameter ratio of 0.4. Green body.

[0030] (3) Drying the green body at 350°C for 1.5 hours at a heating rate of 3°C / min, and then sintering at 1650°C for 4 hours at a heating rate of 7°C / min to obtain porous zinc aluminate ceramics.

[0031] After testing, the porous zinc aluminate ceramic prepared in this embodiment has an av...

Example Embodiment

[0032] Example three

[0033] (1) Mix 3 parts of basic zinc carbonate, 30 parts of boehmite, 4 parts of lithium fluoride, and 4 parts of absolute ethanol in parts by weight. The zirconia ball is used as the ball milling medium and ball milled at 800r / min for 8 hours. , Put the ball-milled mixed powder into a drying box, and dry the slurry at 70°C for 4 hours. After drying, the slurry is sieved through a 35 mesh screen to obtain a mixed powder.

[0034] The aluminum-containing compound is a provider of aluminum oxide, which can be converted into aluminum oxide after high-temperature oxidation. The aluminum-containing compound may be one or more of aluminum aluminum carbonate, aluminum hydroxide, and boehmite.

[0035] (2) After the powder in step (1) is dry-pressed on a tablet press with a pressure of 140 MPa, it is cold isostatically pressed at a pressure of 180 MPa to form a cylindrical sample with a thickness to diameter ratio of 0.5. Green body.

[0036] (3) Drying and holding th...

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Abstract

The invention provides a preparation method of porous zinc aluminate ceramics with high wave permeability, which belongs to the technical field of functional ceramics. The preparation method comprisesthe following steps: (1) mixing 1 to 4 parts of basic zinc carbonate, 10 to 40 parts of aluminum-containing compound and 1 to 5 parts of lithium fluoride to obtain mixed powder; (2) dry pressing themixed powder of the step (1), and then molding the powder in a cold isostatic pressing manner to obtain a green body; and (3) drying the green body at 200 to 350 DEG C, preserving the heat, sinteringat 1450 to 1650 DEG C, and preserving the heat for 2 to 4 hours to obtain porous zinc aluminate ceramics. Zinc oxide and aluminum oxide which are obtained by heating and decomposing basic zinc carbonate and aluminum-containing compound react and are sintered into zinc aluminate; CO2 and H2O gas released by heating and decomposing basic zinc carbonate and aluminum-containing compound as well as volatilized LiF are used as a pore forming agent; and an average aperture size of the prepared porous ceramics is about 500 nm to 1.2 micrometers, the porosity is 30 to 65 percent, the heat conductivityis 0.3 to 1.5 W/mK, the pressure resisting strength is 20 to 80 Mpa, the dielectric constant is 2.0 to 4.5 (the frequency range is 0.3 to 300 GHz), and the dielectric loss is 10<-4> to 10<-3>.

Description

technical field [0001] The invention belongs to the technical field of functional ceramics, and in particular relates to a method for preparing porous zinc aluminate ceramics with high wave permeability. Background technique [0002] The wave-transparent material used in the aerospace field is a multifunctional dielectric material that protects aircraft from communication and guidance in harsh environments. One of its applications is to prepare radome for aircraft (such as launch vehicles, spacecraft, missiles, etc.). With the development of aerospace technology and the needs of modern warfare, the flight Mach number of aircraft continues to increase, and the temperature and thermal shock that the radome needs to withstand are getting higher and higher, requiring it to maintain structural integrity and protection under more severe conditions. The permeability to high-temperature and high-frequency electromagnetic waves puts forward higher performance requirements for wave-tr...

Claims

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Application Information

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IPC IPC(8): C04B35/44C04B38/02
CPCC04B35/44C04B38/02C04B2235/3218C04B2235/3284C04B2235/442C04B2235/445C04B2235/6562C04B2235/96C04B2235/9607C04B38/0054C04B38/0074
Inventor 付萍李沁键薛开诚杜飞鹏林志东陈喆
Owner WUHAN INSTITUTE OF TECHNOLOGY
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