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Silicon carbide refractory castable
Dec 19, 2018

Silicon carbide refractory castables are the development of SiC refractory products (bricks, plates, rods, tubes and crucibles, etc.). Generally, SiC refractory castables are formulated with low cement and ultra-low cement, with SiC as the main raw material, and aluminum cement (CA-70C or CA-80C, etc.) and combined with nf-SiO2 and Al2O3 micropowder as the combination. Agent. However, the following problems are encountered in the production of SiC amorphous refractory materials, especially SiC refractory castables:

(1) SiC has water repellency, which results in poor fluidity of the SiC refractory castable, poor workability, and low density of the cast body.

(2) SiC is difficult to sinter, and thus it is not easy to obtain a high-strength sintered body.

In order to improve the fluidity of the silicon carbide refractory castable, it is necessary to select a SiC raw material having a small influence on fluidity as a SiC source for producing a silicon carbide refractory castable. This can be achieved by changing the shape of the SiC particles and adjusting the type of dispersant (water reducer) and the amount thereof (ie, improving the fluidity and workability of the SiC refractory castable).

Since the SiCa particles are needle-shaped, segregation occurs during vibration molding, and it can be concluded that the sample a needs to be added with more water to have better fluidity. The SiC is a spherical particle, which makes the SiC refractory castable body more dense, so the sample c does not need to add too much water.

It can be seen that the spherical SiC particles have better performance than the acicular SiC particles for the production of SiC refractory castables.

The results show that the fluidity and construction properties of SiC refractory castables can be improved by replacing some of the angular SiC raw materials or sheets with uf-SiC to add more effective dispersants (water reducing agents) such as SM and sodium polyacrylate. .

The purpose of blending Si powder into the SiC refractory castable is to improve the oxidation resistance of the material. The particle-optimized SiC granular material was prepared by using 75% AI2O3 pure aluminate cement as the binder and Uf-SiO2 (95% SiO2) as the auxiliary binder to form the hydration and coagulation combined system. The effect of adding different amounts of Si powder on the oxidation resistance of SiC refractory wound material.

Uf-SiO2 is used in the SiC refractory castable bonding system to improve the physical properties of the material. When the addition amount of Uf-SiO2 reaches a certain value, the refractory castable has higher strength, especially the strength after the middle temperature treatment is nearly doubled, and the mixed water consumption of the material is reduced by 0.9% or more.

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