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A silicon nitride-based composite material antenna window and its preparation method

A composite material and silicon nitride-based technology, which is applied in manufacturing tools, additive processing, ceramic molding machines, etc., can solve problems such as large interface stress, large difference in thermophysical properties, and difficulty in preparing silicon nitride-based antenna windows. Achieve the effect of eliminating interface stress and simple process

Active Publication Date: 2020-07-21
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Silicon nitride-based composite materials have good ablation resistance, high temperature mechanical properties, high temperature wave transmission properties, thermal shock resistance, etc., and have great application potential in hypersonic aircraft antenna windows, so they have been widely studied. Some technologies are still difficult to prepare silicon nitride-based antenna windows with broadband wave transmission characteristics
[0003] For silicon nitride-based wave-transmitting materials, the size of the half-wavelength is generally used to design the antenna window, but it only has good wave-transmitting performance in the set frequency range
In order to obtain broadband wave-transmitting characteristics and have good wave-transmitting performance in more than two frequency ranges, there are three main methods that can be used: one is to use silicon nitride-based wave-transmitting materials with low dielectric constant to prepare thin-walled Antenna window, the choice of material system is limited, it is difficult to meet the structural strength and other performance requirements of the antenna window at the same time
The second is to design a sandwich structure so that the antenna window has better wave-transmitting performance in more than two frequency bands. However, due to the large difference in thermophysical properties between different layer materials, there is a large interface stress, which affects the use of high-speed aircraft wave-transmitting materials. process reliability
However, there is no simple and controllable preparation method that can meet the requirements of the preparation of silicon nitride-based wave-transparent materials with different dielectric constant gradients.

Method used

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  • A silicon nitride-based composite material antenna window and its preparation method
  • A silicon nitride-based composite material antenna window and its preparation method
  • A silicon nitride-based composite material antenna window and its preparation method

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preparation example Construction

[0039] The invention provides a method for preparing a silicon nitride-based composite material antenna window, comprising the following steps:

[0040] Step S1: According to the change law of the dielectric constant of the antenna window of the silicon nitride-based composite material with the thickness, the change law of the porosity with the thickness is determined, and then the solid phase content of the ceramic slurry for preparing the silicon nitride-based composite material is determined. The law of change.

[0041] The different broadband wave-transmission requirements of the antenna window can be realized through the design of the gradient change form of the dielectric constant of the wave-transmissive material. The intrinsic dielectric constant of the silicon nitride-based composite material is a certain value, and the dielectric constant of air is approximately 1. The introduction of pores in silicon nitride based composites will reduce the dielectric constant of si...

Embodiment 1

[0091] This embodiment provides a method for preparing a silicon nitride-based composite material antenna window, which includes the following steps in sequence:

[0092] Step S1: The dielectric constant and thickness of the silicon nitride-based composite antenna window are designed as follows: the dielectric constant decreases linearly from 5.8 to 1.8 in the thickness direction, and the change size in the thickness direction is 9.75mm, and then the dielectric constant is from 1.8 to 1.8. 4.8 Linear increase, the thickness direction change size is 6.25mm. The corresponding relationship between dielectric constant, porosity and solid phase content is determined through experiments, and factors such as sintering shrinkage rate and machining allowance are considered to determine the change law of solid phase content in ceramic slurry with thickness, specifically as follows figure 2shown. The solid phase content decreases linearly from 60vol% to 10vol% in the thickness directio...

Embodiment 2

[0102] This embodiment provides a method for preparing a silicon nitride-based composite material antenna window, which includes the following steps in sequence:

[0103] Step S1: The dielectric constant and thickness of the silicon nitride-based composite material antenna window are designed as follows: in the thickness direction, the dielectric constant decreases from 5.8 to 1.8 according to the parabolic equation, and the thickness direction changes to 9.75mm, and then the dielectric constant is determined by From 1.8 to 3.2, the parabola equation increases incrementally, and the change size in the thickness direction is 6.25mm. The corresponding relationship between the dielectric constant, porosity and solid phase content was determined through experiments, and the factors such as sintering shrinkage and machining allowance were comprehensively considered to determine the variation law of the solid phase content in the ceramic slurry with the thickness, as follows: Figur...

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Abstract

The invention provides a silicon nitride-based composite material antenna window and a preparation method thereof. The change rule of the porosity along with the thickness is determined according to the requirement of the dielectric constant of an antenna window along with the change rule of the thickness, and the change rule of the solid phase content of the ceramic slurry for preparing the silicon nitride-based composite material along with the thickness is further determined; in the 3D printing process, according to the change rule of the solid phase content of the ceramic slurry along withthe thickness, the adding quality of the first slurry containing the ceramic phase and the hydrosol is controlled, layer-by-layer printing is carried out to obtain a ceramic slurry gel block, low-temperature freezing and vacuum freeze drying are carried out, the silicon nitride-based composite materials with the dielectric elevator degree can be obtained after sintering and cooling, and the silicon nitride-based composite material antenna window is machined and prepared. The silicon nitride-based composite material antenna window is integrally prepared and eliminates the interface stress, andis safe and reliable in use, simple in process and capable of meeting the different wide-frequency wave-transmitting requirements.

Description

technical field [0001] The invention relates to the technical field of antenna window preparation, in particular to a silicon nitride-based composite material antenna window and a preparation method thereof. Background technique [0002] The antenna window is a key component to protect the normal operation of hypersonic aircraft communication, telemetry, guidance and other systems. It must not only adapt to extreme environments such as aerodynamic heat and aerodynamic loads during high-speed flight, but also need to meet the harsh electrical performance proposed by the aircraft control circuit. Therefore, it must meet multiple functional requirements such as heat resistance, load bearing, wave penetration, and thermal shock resistance. In recent years, with the application of advanced technologies such as high-precision guidance technology, frequency agility technology, and multi-mode working methods, the antenna window is required to have broadband wave-transmitting charact...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B28B1/00B28B11/24C04B35/584C04B35/622C04B35/634B33Y10/00B33Y70/10B33Y40/20
CPCB28B1/001B28B11/243B33Y10/00B33Y70/00C04B35/584C04B35/622C04B35/63488C04B2235/386C04B2235/6026
Inventor 刘强叶枫张海礁张标高晔
Owner HARBIN INST OF TECH
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