Effect Of Industrial Carbon Black Addition On Properties Of Multiphase Bonded Silicon Carbide Refractories

In order to study the effect of industrial carbon black on the properties of composite bonded silicon carbide refractory, the silica particles (3 ~ 1, 1~0.088 mm), fine powder (<0.088 mm), silicon powder (<0.088 mm), industrial carbon black (grade N990), SiO2 powder (d50=0.26) were used The composite bonded silicon carbide samples were prepared by precasting and heat treatment at 1 400 ℃ in nitrogen atmosphere, and rho -Al2O3 powder (d50= 6.0μm) were the main raw materials. The physical properties, phase composition and microstructure of N990 samples were studied at the addition amounts (w) of 2.5%, 3.0% and 3.5%. The results showed as follows :1) With the increase of N990 addition, the fluidity of mud was improved, and the release strength and drying strength were increased. 2) With the increase of N990 addition, the apparent porosity of the nitrided samples increased, the bulk density and flexion strength decreased, the free C content increased, and α-Si3N4 decreased. 3) With the increase of the amount of N990, the uniformity of the microstructure of the samples after nitriding becomes worse due to the increase of the probability of carbon black particles agglomeration. Si-C and Si-N reacted and sintered, and in addition to continuous flocculation matrix, dense island-like β-SiC or O '-SiAlON phases appeared locally. Comprehensive analysis shows that the sample with carbon black content (w) of 3.0% can better meet the needs of material preparation and properties.

Key words: industrial carbon black, multiphase bonded silicon carbide, casting molding, microstructure

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