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A method for preparing samples for testing fiber dielectric properties by high-q cavity method

A technology of dielectric properties and fibers, applied in the field of sample preparation, can solve the problems of large dispersion and instability of test results

Active Publication Date: 2019-11-05
BEIHANG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The existing sample preparation method generally adopts the method of grinding and mixing fibers with paraffin wax, but the dielectric properties of the fibers obtained by this method are tested, and the test results are relatively discrete. In the test results, the upper and lower surfaces of the sample The test result difference is 0.1~0.2, unstable

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  • A method for preparing samples for testing fiber dielectric properties by high-q cavity method
  • A method for preparing samples for testing fiber dielectric properties by high-q cavity method
  • A method for preparing samples for testing fiber dielectric properties by high-q cavity method

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preparation example Construction

[0030] The present invention provides a kind of preparation method that is used for the sample of high Q cavity method testing fiber dielectric property, comprises the following steps:

[0031] (1) Disperse the fiber to be tested in water to obtain a fiber dispersion; the length of the fiber to be tested is 1 ± 0.2mm;

[0032] (2) Suction filtering the fiber dispersion to obtain a fiber mat;

[0033] (3) impregnating liquid paraffin in the fiber mat to obtain a prepreg; the mass ratio of the fiber mat to liquid paraffin is 1: (3-5), and the thickness of the prepreg is 0.6-1.0mm ;

[0034] (4) Lay 4 to 5 layers of the prepregs and then perform hot-press molding and grinding in sequence to obtain samples for testing the dielectric properties of fibers by the high-Q cavity method.

[0035] In the invention, the fiber to be tested is dispersed in water to obtain a fiber dispersion; the length of the fiber to be tested is 1±0.2mm. The present invention has no special limitation ...

Embodiment 1

[0054] Soak the M110 type silicon nitride fiber in acetone at 50°C for 3 hours, and then chop it into 1±0.2mm to obtain the fiber to be tested;

[0055] Under magnetic stirring conditions (rotating speed is 300r / min, stirring time is 30min), described fiber to be tested is dispersed in deionized water, obtains fiber dispersion liquid; Wherein, the consumption ratio of described fiber to be tested and deionized water is 0.3g: 300mL;

[0056] Use a glass rod to guide the fiber dispersion into a sand core suction filter device for suction filtration, and dry the obtained filter cake at 100° C. for 1.5 h to obtain a fiber mat; 4 fiber mats were prepared in this example. The mass is 0.378g respectively (the physical figure is shown in image 3 shown), 0.365g, 0.334g, 0.351g;

[0057] The fiber mats are respectively placed on the steel plates covered with release paper, then liquid paraffin is added dropwise on the fiber mats (the mass ratio of the fiber mats to liquid paraffin is...

Embodiment 2

[0061] Soak the M235 type silicon nitride fiber in acetone at 50°C for 3 hours, and then chop it into 1±0.1mm to obtain the fiber to be tested;

[0062] Under magnetic stirring conditions (rotating speed is 400r / min, stirring time is 20min), described fiber to be tested is dispersed in deionized water, obtains fiber dispersion liquid; Wherein, the consumption ratio of described fiber to be tested and deionized water is 0.2g: 350mL;

[0063] Use a glass rod to guide the fiber dispersion into a sand core suction filter device for suction filtration, and dry the resulting filter cake at 80°C for 2 hours to obtain a fiber mat; 4 fiber mats were prepared in this example. 0.353g, 0.325g, 0.344g, 0.362g respectively;

[0064] The fiber mats are respectively placed on the steel plate with release paper on the surface, then liquid paraffin is added dropwise on the fiber mats (the mass ratio of the fiber mats to liquid paraffin is 1:3.2), so that the liquid paraffin Soak the whole fib...

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Abstract

The invention relates to the technical field of testing of dielectric properties of fibers and in particular relates to a preparation method of a sample for testing the dielectric properties of the fibers by adopting a high Q cavity method. According to the preparation method, the length of fibers to be detected is controlled to be 1+ / -0.2mm and an isotropic sample is easy to prepare; suction filtration is adopted to ensure uniform distribution of the fibers in a fiber felt; the sample is prepared by adopting 4 to 5 layers of prepreg; the uniform distribution of the fibers in the sample can beensured, and the quality of the fibers in the sample also can meet actual determination requirements (the mass percent of the fibers can reach 20 percent); system errors are reduced; hot pressing molding and polishing are adopted so that the sample has a smooth surface, a uniform thickness and high planeness, and a stability test can be carried out on the dielectric properties of the fibers. Theresult of the embodiment shows that the sample prepared by the preparation method can realize the stability test of the dielectric properties of the fibers, has high repeatability and small discreteness and can be applied to the tests of the dielectric properties fibrous materials very well.

Description

technical field [0001] The invention relates to the technical field of fiber dielectric performance testing, in particular to a method for preparing a sample for testing fiber dielectric performance by a high-Q cavity method. Background technique [0002] As a composite material reinforcement with excellent performance, fiber has been widely used in various fields. Wave-transparent materials should usually have high electromagnetic wave transmittance and low dielectric constant and loss. They have been widely used in the fields of launch vehicles, spacecraft, missiles and returnable satellites. Accurately test the dielectric constant and Loss becomes the basis for designing wave-transparent composite materials. [0003] At present, there are two main methods for testing the dielectric properties of materials, network parameter method and resonant cavity method. The network parameter method is to put the sample to be tested into the test sensor, such as various types of mic...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N1/28
CPCG01N1/28
Inventor 李敏李喆王绍凯顾轶卓李庆辉韩建超张佐光
Owner BEIHANG UNIV
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