Prepn of dense water-base silicon nitride suspension

Abstract

This invention relates to a preparation method for aqueous concentrated suspension of silicon nitride. Firstly, silicon nitride powder is compounded into a slurry, its pH value is regulated with tetramethyl ammonium hydroxide, then the slurry is ground in ball mill, the above-mentioned powder is washed several times with deionized water as medium to remove solubable matter and high-valency counterion, it is thermo-insulated in air atmosphere, and finally the modified silicon nitride powder is added to high-purity deionized water, the suspension is regulated for pH value with tetramethyl ammonium hydroxide and is further ground in ball mill so to prepare the aqueous concentrated suspension of silicon nitride with low viscosity and high solid-phase content. By use of silicon nitride powder from different sources with similar good dispersivity, the aqueous concentrated suspension with solid-phase content higher than 50 vol.% can be prepared.

Description

technical field [0001] The invention relates to a method for preparing a silicon nitride water-based concentrated suspension, belonging to the technical field of ceramic materials. Background technique [0002] Silicon nitride-based ceramics have excellent properties such as high strength, high hardness, oxidation resistance, corrosion resistance and thermal shock resistance, and are a promising high-temperature structural material. However, silicon nitride ceramics manufactured by conventional processes limit their application range due to reasons such as high cost and low reliability, which are also two major problems facing the application of all high-performance ceramics. The molding process is an important link in the preparation of ceramic materials, and it is also a key link in improving the uniformity of ceramic bodies and solving the reliability of ceramic materials. The in-situ solidification colloidal molding process proposed in recent years, such as Gel-casting ...

AI Technical Summary

Problems solved by technology

The limitations of this method are: 1) With the different production processes, the dispersion characteristics of ceramic powder are very different for the same dispersant; and, 2) even if the same brand of powder provided by the same manufacturer, different batch numbers, the dispersion performance may also have a large difference

For Si powder produced by direct nitriding method 3 N 4 Powder, currently only a few researchers have prepared a water-based concentrated suspension with a solid phase content higher than 50vol% for powder with good initial dispersion performance, but the method is not universal

And for the Si prepared by pyrolysis of imine-based silicon 3 N 4 Powder (represented by the products of Ube Corporation in Japan), no one in the world has prepared a water-based concentrated suspension with a solid phase content of 50vol%.

[0004] To sum up, people still don't know the key factors to control the dispersibility of silicon nitride powder in water, and haven't found a simple and easy treatment method to make silicon nitride powder of different manufacturers and brands have similar Good dispersion performance, making its water-based suspension reach the highest possible solid content required by the in-situ solidification molding process