Abstract
Excellent Fe3Si-Si3N4-SiC composites were successfully prepared with FeSi75 and SiC as main starting materials by nitridation reaction(at 1300°C for 8Hrs). The material properties were studied; the ferrosilicon nitridation mechanism was analyzed through chemical thermodynamics; phase composition, microstructure, corrosion resistance of products were also investigated. The results are shown that the comprehensive properties of Fe3Si-Si3N4-SiC are outstanding. The nitridation products are fiber-like α-Si3N4 and rod-like β-Si3N4, which makes better mechanical behavior due to fiber reinforcement; a great deal of Fe3Si intermetallic compounds uniformly distribute in matrix, which is one of the products of Fe-Si nitridation and as a plastic phase forming in grain boundary optimizes the performance of products. Chemical thermodynamic analysis is shown that the fiber-like α-Si3N4 is formed by SiO(g) and N2(g) reaction which also increases the rate of nitridation. Fe3Si-Si3N4-SiC material has high corrosion resistance. Now it has been successfully applied to one 2000M3 domestic steel plant, the blast furnace operation goes well.
Highlights
Due to their excellent properties such as high temperature strength, low thermal expansion coefficient, high refractoriness under load and good chemical stability, silicon nitride bonded silicon carbide (Si3N4-SiC) materials have been used increasingly as a refractory in blast furnaces [1,2,3,4,5,6,7,8,9,10]
In order to farther improve properties of the material, a metallic plastic phase Fe3Si was introduced into the grain boundary of Si3N4-SiC composite
For the sake of compounding metal with ceramic aggregates, preparation of Fe3Si-Si3N4-SiC composites by nitriding ferrosilicon alloy based on Si3N4-SiC is proposed
Summary
Due to their excellent properties such as high temperature strength, low thermal expansion coefficient, high refractoriness under load and good chemical stability, silicon nitride bonded silicon carbide (Si3N4-SiC) materials have been used increasingly as a refractory in blast furnaces [1,2,3,4,5,6,7,8,9,10]. Si3N4-SiC possesses some weaknesses, such as great brittleness, poor thermal shock resistance and bad thermal conductivity, which restricts its further application. In order to farther improve properties of the material, a metallic plastic phase Fe3Si was introduced into the grain boundary of Si3N4-SiC composite. Si3N4-SiC materials with uniformly dispersed metallic plastic phase is expected to have higher thermal conductivity and thermal shock resistance in favour of enhancing blast furnace cooling rate. The research on Fe3Si-Si3N4-SiC materials is rarely reported in domestic and oversea research [11,12,13,14], this research hopes to provide some useful reference
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