Preparation method for silicon carbide ceramic tube or rod

Abstract

The invention relates to a preparation method for a silicon carbide ceramic tube or rod. An extrusion moulding method is adopted to form a blank body; a normal pressure sintering method is adopted for sintering; and submicron level silicon carbide powder and additives are taken as main raw materials. The preparation method comprises the following steps: 1) carrying out ball milling on the main raw materials by a dry method, adding water, a dispersant, a plasticizer, a lubricant and a liquid state binder, and then carrying out ball milling by a wet method; 2) adopting a spray granulation process to granulate silicon carbide slurry; 3) extruding the blank body by a one-shot direct extrusion moulding method after vacuum pug, corrosion, and vacuum pug; 4) drying the molded blank body by a stage drying mechanism; and 5) placing the blank body of the silicon carbide ceramic tube or rod in a vacuum furnace and carrying out sintering for two times by taking argon gas as protective gas. The high temperature resisting strength and the corrosion resistance of the silicon carbide ceramic tube or rod prepared by the method are both better than those of a reactive sintered product. Compared with a hot press sintering method, the method has lower limit on the product shape and size, and lower cost. The method is suitable for the industrialized production.

Description

technical field [0001] The invention relates to a preparation method, in particular to a preparation method of a silicon carbide ceramic tube or rod. Background technique [0002] As a high-temperature structural ceramic, silicon carbide ceramics have many excellent properties, such as wear resistance, high thermal conductivity, heat resistance, corrosion resistance, and excellent mechanical and thermal properties. Silicon carbide ceramics have been widely used in machinery, electronics, petrochemical, metallurgy and other industrial fields, as well as the national defense industry, and have been recognized internationally as the fourth basic material since metal, alumina, and cemented carbide. [0003] Due to its structural characteristics, silicon carbide ceramic tubes or rods are generally formed by chemical vapor phase synthesis, isostatic pressing, grouting molding, injection molding and extrusion molding, but the above methods still have the following problems: [000...

AI Technical Summary

Problems solved by technology

[0004] 1) The method of chemical vapor phase synthesis is to deposit a silicon carbide layer on the rod-shaped graphite, and then remove the graphite by high-temperature oxidation to obtain a silicon carbide tube or rod. A method for manufacturing silicon carbide tubular components using chemical vapor synthesis, but this method is difficult to produce thick-walled silicon carbide tubes and has high production costs, making it difficult to achieve large-scale production

[0005] 2) Although isostatic pressing can form a compact green body, as Patent No. 99120189.2 "Silicon Carbide Roller for Roller Kiln and Its Manufacturing Method" discloses a method of manufacturing silicon carbide roll for isostatic pressing, but Its cost is high, and continuous production cannot be realized, and the yield is low

[0006] 3) The premise of grouting molding is to obtain a stable suspension with high solid content, and a variety of additives are often added to silicon carbide ceramic ingredients, so it is difficult to achieve a uniform and stable suspension with high solid content

[0007] 4) Injection molding has the disadvantages of long degreasing time and difficult control

[0008] 5) Extrusion molding is a low-cost, continuous method for producing ceramic tubes or rods, but it is difficult to form a dense green body

However, due to the presence of more free silicon in the reaction sintered product, its strength, corrosion resistance and high temperature stability are poor

The cost of hot pressing and sintering is relatively high, and the shape of the product is greatly restricted

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