CN102978500A - High thermal conductivity microwave attenuation AlN-based composite material and preparation method thereof - Google Patents
High thermal conductivity microwave attenuation AlN-based composite material and preparation method thereof Download PDFInfo
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- CN102978500A CN102978500A CN201210536786XA CN201210536786A CN102978500A CN 102978500 A CN102978500 A CN 102978500A CN 201210536786X A CN201210536786X A CN 201210536786XA CN 201210536786 A CN201210536786 A CN 201210536786A CN 102978500 A CN102978500 A CN 102978500A
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Abstract
The invention discloses a high thermal conductivity microwave attenuation AlN-based composite material and a preparation method thereof, belonging to the field of microwave electronics vacuum technology. According to the high thermal conductivity microwave attenuation AlN-based composite material, (0.1-2.0)vol.% of CNTs (Carbon Nano Tubes) and (1.0-20.0)vol.% of W which are used as metal phases and (100-CNTs-W)vol.% of AlN which is used as a medium phase are used. The preparation method comprises the steps of: mixing the CNTs, the W powder and the AlN powder according to a certain volume ratio to obtain a mixture; and forming and sintering the mixture to obtain a CNTs/W/AlN complex phase microwave absorbing material. The high thermal conductivity microwave attenuation AlN-based composite material has relative density being more than 98 percent, dielectric constant being 17-25 and dielectric loss angle tangent being more than 0.04, has excellent wave absorbing property within a range of 70kHz-1MHz, is especially applicable to preparation of a microwave electric vacuum device, and can be applied to a passive electronic countermeasure and microwave measurement system.
Description
Technical field
The present invention relates to a kind of microwave attenuator material and preparation method, be particularly related to a kind of environmental protection microwave attenuator material and technology of preparing that is applied under the vacuum condition, specifically the preparation method of a kind of carbon nanotube/tungsten/aluminium nitride (CNTs/W/AlN) multi-phase microwave absorbing material belongs to microwave electron vacuum technique field.
Background technology
The microwave attenuation material is widely used in the microwave electron tube, and it loads high frequency interaction circuits such as resonator cavity and slow-wave structures, reaches widening frequency band, suppresses vibration and eliminates the effect of other non-Design Mode.In addition, the microwave attenuation material is widely used in the passive electronic countermeasure, and the microwave insulated chamber that the important facility in ground, aerial aircraft and building maintained secrecy etc. all needs to prevent with the microwave attenuation material in a large number the other side's discovery, tracking and attack.The microwave attenuation material also is used widely in waveguide and coaxial line as losser and load in microwave measurement system, is described as " heart " of electronic system.
At present, the electron tube bulk absorption equipment material of domestic employing mainly is carburizing porous alumina decay pottery and BeO base composite attenuation pottery.Carburizing porous alumina decay pottery is because discharge quantity is large, and intensity is lower, the decling phase skewness, and the carburizing yield rate is lower, and it is low that vesicular structure makes it thermal conductivity, and the use of high power valve has been caused certain obstacle; The toxicity of BeO makes the safety precaution of BeO base composite attenuation pottery be difficult to reach requirement.
People have turned to AlN to sight, and AlN is nontoxic, and its thermal conductivity theoretical value can reach 320 W.m
-1.K
-1, can near the thermal conductivity of BeO, be Al approximately
2O
38 times of thermal conductivity.And AlN has moderate dielectric coefficient, good chemistry and thermostability, very high resistivity.As the medium phase, not only be conducive to improve the thermal conductivity of attenuating material with AlN, also help the microwave attenuation performance that improves material.This with, take the attenuating material of AlN as base, outgassing rate is low under high vacuum environment, with oxide cathode good compatibility is arranged, and good thermostability and mechanical property are arranged under the high temperature more than 1000 ℃, can form hermetic seal with copper.Therefore, development AlN base microwave attenuation material, the particularly raising of its fade performance and thermal conductivity, be the microwave attenuation material at the microwave electron tube, the development trend in platinotron is used particularly.
In the HIGH-POWERED MICROWAVES electron tube, to one of attenuating material basic demand be, specific inductivity is high, and imaginary part is controlled, and this is the key that realizes the attenuating material high attenuation.But pure aluminium nitride ceramics has that specific inductivity is low, dielectric loss is low and resistivity is crossed high, therefore is everlasting wherein to add some conductive phases and adjusted.Can form liquid because the sintering temperature of AlN about 1700 ℃, is added the excessively low conductive phase of fusing point in sintering process, can not get needed result.The Cheng Ji of HeFei University of Technology is valued among the AlN and adds the 34%-40%(massfraction) Mo, obtained in the 2.2-2.5GHz scope, having the material of good absorbing property, the Yang Zhimin of Beijing Non-Ferrous Metal Research General Academy adds W or the Mo of 1.65%-2.01% in AlN, obtained the reflection loss amount of 20.0dB in the wider frequency section., have and the thermal expansivity of AlN coupling and higher thermal conductivity as the microwave attenuation agent with conductive particle W.
Studies show that in a large number carbon nanotube has excellent conductivity, good heat-conductive characteristic and absorbing property, is the most potential absorbing material of a new generation.Prepare in the experiment of ceramic of compact at CNT and ceramic matrix direct combination, when sintering temperature is higher than 1400 ℃, CNT composite attenuation pottery behind the high temperature sintering has preferably fade performance, but when sintering temperature reaches 1600 ℃, decrement is very little, ceramic matrix and CNT react and escape under this temperature, therefore do not embody its due microwave absorbing effect, need to add metallic substance, principle of design according to composite diphase material mutual supplement with each other's advantages, in the AlN matrix, add conductive particle, it is evenly distributed in insulation and the high AlN body material of thermal conductivity, can improve specific inductivity and the loss of material, realize the novel attenuating material of excellent combination property.
Large specific surface area and length-to-diameter ratio that carbon nanotube has, the special constructions such as small size, and its special electromagnetic property of showing are so that the application of carbon nanotube on stealth material, absorbing material has very large potentiality.With traditional microwave decay and compare, carbon nanotube has that absorption band is wide, decrement is large, consumption is few, high stability, anti-oxidant, the advantage such as quality is light, makes the CNTs complex phase ceramic show unusual absorbing property.The step literary composition of Nanjing University of Technology is won in the AlN matrix an amount of Graphite Powder 99 of interpolation and is prepared the AlN-C composite diphase material with excellent microwave attenuation performance, the AlN-C dielectric resonance loss chamber of development in the research of AlN-C composite diphase material.The people such as the Yu Liang of China Iron ﹠ Steel Research Institute Group (CISRI) have studied AlN-SiC composite attenuation material preparation and microwave attenuation performance thereof, at AlN base microwave attenuation Material Field, the continuous exploration of researchist further improves the absorbing property of material, to improve the use range of material.
Summary of the invention
The present invention is directed to the defective of existing ceramet group microwave absorbing material hot pressing, aim to provide the microwave attenuation sintered compact that a kind of SPS Fast Sintering obtains high-compactness, high loss, this material can satisfy specific inductivity 17 ~ 25, tangent of the dielectric loss angle〉0.04, in 70kHz ~ 1MHz scope, has good absorbing property
For above-mentioned purpose, the technical solution used in the present invention is as follows:
A kind of microwave attenuator material with high heat conductivity is chosen CNTs and W as metallographic phase, and AlN is the medium phase, comprises CNTs:(0.1-2.0) vol.%, W:(1.0-20.0) vol.% and AlN:(100-CNTs-W) vol.%.
Another object of the present invention provides a kind of preparation method of above-mentioned microwave attenuator material with high heat conductivity, and the implementation step is:
(1) CNTs powder, W powder and AlN powder are pressed (0.1-2.0): (1.0-20.0): mix after the volume ratio proportioning (78.0-98.9), the employing Stainless Steel Ball is mill ball, take dehydrated alcohol as grinding medium, the mass ratio of mill ball and raw material powder is (4-6): 1, Ball-milling Time is 10 ~ 40min, obtains the mixed powder slurry.
(2) the mixed powder slurry is placed vacuum drying oven, obtain mixed powder at 70-90 ℃ of lower vacuum-drying 2-4h.
(3) mixed powder is placed graphite jig carry out the SPS sintering and prepare the composite ceramics sample, its sintering temperature is 1400 ~ 1700 ℃, and soaking time is 2 ~ 10min, and sintering pressure is 30-40MPa, temperature rise rate is 100-150 ℃/min, obtains the CNTs-W-AlN composite block material.
(4) shape and size during by concrete use are processed with composite block material, namely obtain the CNTs-W-AlN composite block material for microwave attenuator.
The hybrid mode of described mixing comprises rolling ball milling, high-energy ball milling, magnetic agitation, ultrasonic wave dispersion.
CNTs/W/AlN multi-phase microwave absorbing material of the present invention, the content of W and CNTs has direct impact to the performance of composite ceramics, and when CNTs content was too much, the number of pores in the composite ceramics increased, and W effectively improves the sintered compact density; In AlN/W, add CNTs, improved the dielectric loss of composite ceramics.The composite ceramics that adds the 1vol.%CNTs preparation in AlN-10vol.%W has excellent dielectric properties, dielectric loss is under 70kHz ~ 1MHz frequency, tan δ〉0.04, specific inductivity: ε＜17.5, be particularly suitable for preparing the microwave electron tube, be used for passive electronic countermeasure and microwave measurement system.
Concrete embodiment
The present invention is described in detail below in conjunction with specific embodiment.
Embodiment 1
(1) will mix after CNTs powder, W powder and the AlN powder volume ratio proportioning by 1:5:94, the employing Stainless Steel Ball is mill ball, and take dehydrated alcohol as grinding medium, the mass ratio of mill ball and raw material powder is 4:1, and Ball-milling Time is 20min.
(2) the described mixed powder slurry of step (1) is placed vacuum drying oven, obtain mixed powder at 70 ℃ of lower vacuum-drying 2h.
(3) place graphite jig to carry out the SPS sintering the described mixed powder of step (2) and prepare the composite ceramics sample, its sintering temperature is 1600 ℃, and soaking time is 10min, and sintering pressure is 30MPa, and temperature rise rate is 100 ℃/min.
(4) shape and size during by concrete use are processed with the described composite block material of step (3), namely obtain the CNTs-W-AlN composite block material for microwave attenuator.Its relative density is 98%, and specific inductivity is 17, and tangent of the dielectric loss angle is 0.035, has good absorbing property in 70kHz ~ 1MHz scope.
Embodiment 2
(1) will mix after CNTs powder, W powder and the AlN powder volume ratio proportioning by 1:10:89, the employing Stainless Steel Ball is mill ball, and take dehydrated alcohol as grinding medium, the mass ratio of mill ball and raw material powder is 4:1, and Ball-milling Time is 20min.
(2) the described mixed powder slurry of step (1) is placed vacuum drying oven, obtain mixed powder at 70 ℃ of lower vacuum-drying 2h.
(3) place graphite jig to carry out the SPS sintering the described mixed powder of step (2) and prepare the composite ceramics sample, its sintering temperature is 1600 ℃, and soaking time is 5min, and sintering pressure is 30MPa, and temperature rise rate is 100 ℃/min.
(4) shape and size during by concrete use are processed with the described composite block material of step (3), namely obtain the CNTs-W-AlN composite block material for microwave attenuator.Its relative density is 98%, and specific inductivity is 17.5, and tangent of the dielectric loss angle is 0.04, has good absorbing property in 70kHz ~ 1MHz scope.
Embodiment 3
(1) will mix after CNTs powder, W powder and the AlN powder volume ratio proportioning by 1:20:79, the employing Stainless Steel Ball is mill ball, and take dehydrated alcohol as grinding medium, the mass ratio of mill ball and raw material powder is 4:1, and Ball-milling Time is 20min.
(2) the described mixed powder slurry of step (1) is placed vacuum drying oven, obtain mixed powder at 70 ℃ of lower vacuum-drying 2h.
(3) place graphite jig to carry out the SPS sintering the described mixed powder of step (2) and prepare the composite ceramics sample, its sintering temperature is 1400 ℃, and soaking time is 5min, and sintering pressure is 30MPa, and temperature rise rate is 100 ℃/min.
(4) shape and size during by concrete use are processed with the described composite block material of step (3), namely obtain the CNTs-W-AlN composite block material for microwave attenuator.Its relative density is 98%, and specific inductivity is 17.3, and tangent of the dielectric loss angle is 0.032, has good absorbing property in 70kHz ~ 1MHz scope.
Embodiment 4
(1) will mix after CNTs powder, W powder and the AlN powder volume ratio proportioning by 0.1:1:98.9, the employing Stainless Steel Ball is mill ball, and take dehydrated alcohol as grinding medium, the mass ratio of mill ball and raw material powder is 4:1, and Ball-milling Time is 20min.
(2) the described mixed powder slurry of step (1) is placed vacuum drying oven, obtain mixed powder at 70 ℃ of lower vacuum-drying 2h.
(3) place graphite jig to carry out the SPS sintering the described mixed powder of step (2) and prepare the composite ceramics sample, its sintering temperature is 1600 ℃, and soaking time is 5min, and sintering pressure is 30MPa, and temperature rise rate is 100 ℃/min.
(4) shape and size during by concrete use are processed with the described composite block material of step (3), namely obtain the CNTs-W-AlN composite block material for microwave attenuator.Its relative density is 99%, and specific inductivity is 19, and tangent of the dielectric loss angle is 0.05, has good absorbing property in 70kHz ~ 1MHz scope.
Embodiment 5
(1) will mix after CNTs powder, W powder and the AlN powder volume ratio proportioning by 0.1:10:89.9, the employing Stainless Steel Ball is mill ball, and take dehydrated alcohol as grinding medium, the mass ratio of mill ball and raw material powder is 4:1, and Ball-milling Time is 20min.
(2) the described mixed powder slurry of step (1) is placed vacuum drying oven, obtain mixed powder at 70 ℃ of lower vacuum-drying 2h.
(3) place graphite jig to carry out the SPS sintering the described mixed powder of step (2) and prepare the composite ceramics sample, its sintering temperature is 1600 ℃, and soaking time is 5min, and sintering pressure is 30MPa, and temperature rise rate is 100 ℃/min.
(4) shape and size during by concrete use are processed with the described composite block material of step (3), namely obtain the CNTs-W-AlN composite block material for microwave attenuator.Its relative density is 98.5%, and specific inductivity is 20, and tangent of the dielectric loss angle is 0.045, has good absorbing property in 70kHz ~ 1MHz scope.
Embodiment 6
(1) will mix after CNTs powder, W powder and the AlN powder volume ratio proportioning by 0.1:20:79.9, the employing Stainless Steel Ball is mill ball, and take dehydrated alcohol as grinding medium, the mass ratio of mill ball and raw material powder is 4:1, and Ball-milling Time is 20min.
(2) the described mixed powder slurry of step (1) is placed vacuum drying oven, obtain mixed powder at 70 ℃ of lower vacuum-drying 2h.
(3) place graphite jig to carry out the SPS sintering the described mixed powder of step (2) and prepare the composite ceramics sample, its sintering temperature is 1600 ℃, and soaking time is 5min, and sintering pressure is 30MPa, and temperature rise rate is 100 ℃/min.
(4) shape and size during by concrete use are processed with the described composite block material of step (3), namely obtain the CNTs-W-AlN composite block material for microwave attenuator.Its relative density is 97.5%, and specific inductivity is 21, and tangent of the dielectric loss angle is 0.056, has good absorbing property in 70kHz ~ 1MHz scope.
Embodiment 7
(1) will mix after CNTs powder, W powder and the AlN powder volume ratio proportioning by 2:1:97, the employing Stainless Steel Ball is mill ball, and take dehydrated alcohol as grinding medium, the mass ratio of mill ball and raw material powder is 5:1, and Ball-milling Time is 40min.
(2) the described mixed powder slurry of step (1) is placed vacuum drying oven, obtain mixed powder at 70 ℃ of lower vacuum-drying 2h.
(3) place graphite jig to carry out the SPS sintering the described mixed powder of step (2) and prepare the composite ceramics sample, its sintering temperature is 1600 ℃, and soaking time is 10min, and sintering pressure is 30MPa, and temperature rise rate is 100 ℃/min.
(4) shape and size during by concrete use are processed with the described composite block material of step (3), namely obtain the CNTs-W-AlN composite block material for microwave attenuator.Its relative density is 96.5%, and specific inductivity is 22, and tangent of the dielectric loss angle is 0.06, has good absorbing property in 70kHz ~ 1MHz scope.
Embodiment 8
(1) will mix after CNTs powder, W powder and the AlN powder volume ratio proportioning by 2:10:88, the employing Stainless Steel Ball is mill ball, and take dehydrated alcohol as grinding medium, the mass ratio of mill ball and raw material powder is 6:1, and Ball-milling Time is 50min.
(2) the described mixed powder slurry of step (1) is placed vacuum drying oven, obtain mixed powder at 90 ℃ of lower vacuum-drying 2h.
(3) place graphite jig to carry out the SPS sintering the described mixed powder of step (2) and prepare the composite ceramics sample, its sintering temperature is 1700 ℃, and soaking time is 10min, and sintering pressure is 40MPa, and temperature rise rate is 140 ℃/min.
(4) shape and size during by concrete use are processed with the described composite block material of step (3), namely obtain the CNTs-W-AlN composite block material for microwave attenuator.Its relative density is 96.8%, and specific inductivity is 23.5, and tangent of the dielectric loss angle is 0.055, has good absorbing property in 70kHz ~ 1MHz scope.
Embodiment 9
(1) will mix after CNTs powder, W powder and the AlN powder volume ratio proportioning by 2:20:78, the employing Stainless Steel Ball is mill ball, and take dehydrated alcohol as grinding medium, the mass ratio of mill ball and raw material powder is 4:1, and Ball-milling Time is 20min.
(2) the described mixed powder slurry of step (1) is placed vacuum drying oven, obtain mixed powder at 90 ℃ of lower vacuum-drying 2h.
(3) place graphite jig to carry out the SPS sintering the described mixed powder of step (2) and prepare the composite ceramics sample, its sintering temperature is 1700 ℃, and soaking time is 10min, and sintering pressure is 40MPa, and temperature rise rate is 150 ℃/min.
(4) shape and size during by concrete use are processed with the described composite block material of step (3), namely obtain the CNTs-W-AlN composite block material for microwave attenuator.Its relative density is 96.7%, and specific inductivity is 25, and tangent of the dielectric loss angle is 0.065, has good absorbing property in 70kHz ~ 1MHz scope.
Claims (3)
1. one kind high heat conduction microwave attenuation AlN based composites, it is characterized in that: choose CNTs and W as metallographic phase, AlN is the medium phase, comprises CNTs:(0.1-2.0) vol.%, W:(1.0-20.0) vol.% and AlN:(100-CNTs-W) vol.%.
2. the preparation method of the described high heat conduction microwave attenuation AlN based composites of claim 1, it is characterized in that: implementation step is:
1) CNTs powder, W powder and AlN powder are pressed (0.1-2.0): (1.0-20.0): mix after the volume ratio proportioning (78.0-98.9), the employing Stainless Steel Ball is mill ball, take dehydrated alcohol as grinding medium, the mass ratio of mill ball and raw material powder is (4-6): 1, Ball-milling Time is 10 ~ 40min, obtains the mixed powder slurry;
2) the mixed powder slurry is placed vacuum drying oven, obtain mixed powder at 70-90 ℃ of lower vacuum-drying 2-4h;
3) mixed powder is placed graphite jig carry out the SPS sintering and prepare the composite ceramics sample, its sintering temperature is 1400 ~ 1700 ℃, and soaking time is 2 ~ 10min, and sintering pressure is 30-40MPa, temperature rise rate is 100-150 ℃/min, obtains the CNTs-W-AlN composite block material.
3. such as right preparation method claimed in claim 2, it is characterized in that: mix rolling ball milling, high-energy ball milling, magnetic agitation, the ultrasonic wave dispersing and mixing mode of comprising described in the step 1).
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110105090A (en) * | 2019-06-12 | 2019-08-09 | 刘华云 | A kind of micron order AlN ceramic loading nanometer Fe composite attenuation material and preparation method |
| CN111205819A (en) * | 2020-01-10 | 2020-05-29 | 中国科学院兰州化学物理研究所 | Carbon nanotube-aluminum nitride wave absorbing agent and preparation method thereof, carbon nanotube-aluminum nitride composite wave absorbing material and application thereof |
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| JPH0226872A (en) * | 1988-07-12 | 1990-01-29 | Sumitomo Electric Ind Ltd | Window for transmitting high-frequency wave |
| CN102515773A (en) * | 2011-12-26 | 2012-06-27 | 中国电子科技集团公司第十二研究所 | Microwave attenuation ceramic material and preparation method thereof |
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2012
- 2012-12-13 CN CN201210536786XA patent/CN102978500A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH0226872A (en) * | 1988-07-12 | 1990-01-29 | Sumitomo Electric Ind Ltd | Window for transmitting high-frequency wave |
| CN102515773A (en) * | 2011-12-26 | 2012-06-27 | 中国电子科技集团公司第十二研究所 | Microwave attenuation ceramic material and preparation method thereof |
Non-Patent Citations (1)
| Title |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110105090A (en) * | 2019-06-12 | 2019-08-09 | 刘华云 | A kind of micron order AlN ceramic loading nanometer Fe composite attenuation material and preparation method |
| CN111205819A (en) * | 2020-01-10 | 2020-05-29 | 中国科学院兰州化学物理研究所 | Carbon nanotube-aluminum nitride wave absorbing agent and preparation method thereof, carbon nanotube-aluminum nitride composite wave absorbing material and application thereof |
| CN111205819B (en) * | 2020-01-10 | 2021-02-19 | 中国科学院兰州化学物理研究所 | Carbon nanotube-aluminum nitride wave absorbing agent and preparation method thereof, carbon nanotube-aluminum nitride composite wave absorbing material and application thereof |
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Application publication date: 20130320 |