Method for preparing highly-pure beta-Sialon ceramic powders

Abstract

The invention provides a method for preparing highly-pure beta-Sialon ceramic powders, which combines a carbothermal reduction nitridation process and nano-pouring technology and comprises the following specific steps: firstly, taking ordered mesoporous silicon dioxide as a main raw material, taking soluble inorganic aluminum salt as an aluminum oxide precursor, taking an organic small molecular compound as a carbon source, and preparing a compound of mesoporous carbon / silicon oxide / aluminum oxide through nanometer pouring; then performing carbothermal reduction nitridation on the compound of the mesoporous carbon / the silicon oxide / the aluminum oxide to prepare a sample; and finally, calcining the sample in air to remove residual carbon, and cooling the sample after residual carbon is removed to prepare a product. The method has the advantages that the synthesis temperature of the preparation method is relatively low, and is favorable for reducing the required energy consumption in production; and the purity of the prepared beta-Sialon ceramic powders is high, and the particle shapes are mainly in a long rod-like shape. The preparation method can be widely used in fields of space flight, metallurgy, chemical industry and the like.

Description

technical field [0001] The invention belongs to the technical field of ceramic materials, and in particular relates to a preparation method for synthesizing high-purity β-Sialon ceramic powder by using a carbothermal reduction nitriding process combined with a nano-casting technology and the β-Sialon ceramic powder prepared by the method. Background technique [0002] and high performance nitride material Si 3 N 4 The structure is similar to that of Sialon as Si 3 N 4 The solid solution can also be divided into two crystal forms, the low-temperature phase α-Sialon and the high-temperature phase β-Sialon. Wherein β-Sialon is β-Si 3 N 4 Z Si-N bonds in the structure are replaced by Z Al-O bonds, and its composition can be expressed as Si 6-z Al z o z N 8-z (where 0<Z≤4.2). Since β-Sialon is easy to grow into a columnar shape, it produces a whisker-like toughening effect, which makes β-Sialon have higher fracture strength and fracture toughness than α-Sialon. Due ...

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Problems solved by technology

At present, the common methods of synthesizing β-Sialon ceramic powder are: (1) high-temperature solid-state reaction method, the preparation process of this method is relatively complicated, and the required synthesis temperature is high (about 1700 ° C)

(2) Self-propagating high-temperature synthesis method, which is a rapid milling method, but the process equipment is complicated, the requirements are high, and the reaction process is difficult to control

(3) Carbothermal reduction nitriding method, this method has a wide range of applications, mainly due to relatively low requirements for equipment and processes, but there are many influencing factors in the synthesis process, and the impurity content in the product is relatively high

[0006] The Chinese invention patent application with the publication number CN1168872A also provides a preparation method of Sialon ceramic powder, which uses a high-temperature self-propagating process. The process equipment is complex, the requirements are high, and the reaction process is difficult to control.

[0007] Furthermore, the Chinese invention patent application with the publication number CN1270153A provides a preparation method of Sialon combined with SiC powder, which mainly uses river sand as a raw material, and there is a large amount of SiC in the synthesis product phase. 2 O (2.9%), Na 2 O (3.5%) content is high, not suitable for high temperature industrial applications

[0008] In short, the initial raw materials used in the method of preparing β-Sialon ceramic powder provided by published patents and literatures are all mechanically mixed, and uneven mixing of raw materials leads to high synthesis temperature and inevitable impurity phases.

In addition, there is no published invention patent about the preparation of β-Sialon ceramic powder by nano-casting using ordered mesoporous silica as raw material

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