A kind of SICN ceramic airgel and its preparation method and application

Abstract

The invention provides a SiCN ceramic airgel and its preparation method and application. The preparation method includes: using polysilazane containing Si-H bonds in molecular structure and containing -CH=CH 2 The silazane oligomer is used as a precursor, and is prepared into a precursor solution under an inert protective atmosphere; the preparation of the precursor wet sol: adding a curing agent to the precursor solution for curing reaction to obtain a precursor wet gel ; Preparation of precursor airgel: dry the precursor wet gel to obtain precursor airgel; Preparation of ceramic airgel: pyrolyze the precursor airgel in an inert protective atmosphere , to obtain SiCN ceramic airgel. The invention also provides the SiCN ceramic airgel prepared by the method and its application. The structure of the precursor used in the method of the present invention has strong designability, avoids the addition of unsaturated aromatic hydrocarbon compounds, and the obtained SiCN ceramic airgel has adjustable components, low free carbon content, high ceramic yield, low density, porosity and specific surface area High, can be used in thermal protection, stealth, fuel reforming or lithium-ion batteries and other fields.

Description

technical field [0001] The invention belongs to the field of ceramic airgel, and in particular relates to a SiCN ceramic airgel and a preparation method and application thereof. Background technique [0002] Airgel is a nanoporous material composed of nanoparticles and has a three-dimensional network skeleton structure. The developed porous structure endows it with different properties from traditional porous materials, especially ultra-low solid content and ultra-high porosity, etc. The characteristics make it have significant advantages in the fields of heat insulation, electromagnetic shielding, energy and chemical industry. At present, the research on aerogels mainly focuses on silica aerogels and carbon aerogels, but pure silica aerogels can be used for a long time below 650 °C, and can only be used for a short time at around 800 °C, and with the increase of temperature As the temperature increases, the thermal conductivity at high temperature increases rapidly, for ex...

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Problems solved by technology

The method for preparing SiCN ceramic airgel by polyvinylsilazane containing C=C double bond and Si-H, because it is a precursor molecule containing C=C double bond and Si-H at the same time, in the gel reaction In the later stage, the reaction will be terminated due to steric hindrance, so there are problems such as low crosslinking degree and weak airgel skeleton, which is not conducive to the control of airgel microstructure

The method of preparing SiCN ceramic airgel by polyvinylsilazane containing C=C double bond and divinylbenzene, since the theoretical carbon content in divinylbenzene is 92%, its addition will inevitably cause ceramic aircondensation The increase of free carbon content in the gel will affect its high temperature oxidation resistance and mechanical properties, and it cannot have low density, high airgel purity, good oxidation resistance, low free carbon content, high porosity, and high specific surface area.

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