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

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...

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.

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