Silicon nitride-based gradient composite material based on outer field auxiliary technology and preparation method thereof

Abstract

The invention belongs to the technical field of a ceramic material, and particularly relates to a silicon nitride-based gradient composite material based on an outer field auxiliary technology and a preparation method thereof. The preparation method comprises the following steps of mixing Si3N4 base body materials, conductive second phase materials, aluminum oxide rare earth oxide mixtures and solvents to obtain silicon nitride-based composite phase ceramic slurry; performing drying and granulation on the silicon nitride-based composite phase ceramic slurry to obtain silicon nitride-based composite phase ceramic mixed powder; sequentially putting at least two kinds of silicon nitride-based composite phase ceramic mixed powder into a mold; then, performing spark plasma sintering to obtain the silicon nitride-based gradient composite material, wherein at least one index of the particle diameter, the type and the addition proportion of the conductive second phase material of the two adjacent layers of silicon nitride-based composite phase ceramic mixed powder is different. According the invention, the silicon nitride-based gradient composite material with different silicon nitride phase composition / microstructure / performance can be prepared fast, precisely and controllably .

Description

technical field [0001] The invention belongs to the technical field of ceramic materials, and in particular relates to a silicon nitride-based gradient composite material based on external field assisted technology and a preparation method thereof. Background technique [0002] Silicon nitride (Si 3 N 4 ) Ceramics have the characteristics of high comprehensive mechanical properties, high temperature resistance, wear resistance, and corrosion resistance. As important structural ceramic materials, they are widely used in aerospace, equipment manufacturing, energy chemical industry, biomedical and other fields. With the development of modern industrial technology, the requirements for material properties have also been continuously improved, and then SiC enhanced by various phases (such as SiC, TiN, TiC, BN, WC, etc.) has appeared. 3 N 4 Composite materials; on this basis, through further structural design at the macro and micro scales, the optimization and improvement of ma...

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Problems solved by technology

However, by changing the composition and content of the layered system of gradient materials, combined with conventional hot-pressing 3 N 4 However, there are many problems such as complex preparation process, long sintering time, difficulty in controlling phase composition, and easy formation of defects in the interface area.

[0005] The existing conventional sintering (atmosphere sintering, hot pressing sintering, air pressure sintering, hot isostatic pressing sintering, etc.) to prepare Si 3 N 4 The process method of gradient-based ceramics is usually to lay a layer of slurry in the mold and after sintering, lay a second layer of slurry on the sintering slurry for sintering, which leads to complicated sample preparation procedures, long sintering period, and each layer The interface area between the materials formed by sintering is easy to form defects; and the increase of sintering time and the increase of sintering temperature will increase the alpha-Si 3 N 4 The degree of phase transition and the phase composition are difficult to control, which weakens the design and controllable range of the phase and microstructure of the gradient material, and severely limits the final Si 3 N 4 Properties and functions of base gradient materials

Existing use of spark plasma sintering technology to prepare Si 3 N 4 A method based on gradient ceramics, by changing the graphite mold structure / position, introducing beta-Si 3 N 4 Seed crystals, or compound SPS sintering on the basis of hot-pressed sintered samples, can realize the manufacture of gradient structures, but the material preparation procedures are cumbersome, the placement of SPS molds, and the controllability and repeatability of the temperature field / gradient layer Low stability, and repeated trials are required, time-consuming and labor-intensive, it is difficult to obtain the ideal gradient phase composition under the premise of ensuring the high density of the material

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