关键词: 工业炭黑, 复相结合碳化硅, 浇注成型, 显微结构

Abstract: In order to study the effect of industrial carbon black on properties of multiphase bonded silicon carbide refractories,the samples were prepared using silicon carbide particles (3-1 and 1-0.088 mm) and fine powder (<0.088 mm),silicon powder (<0.088 mm),industrial carbon black (N990),microsilica (d₅₀=0.26 μm) and ρ-Al₂O₃ micropowder (d₅₀=6.0 μm) as the main raw materials,casting molding and heat treating at 1 400 ℃ in nitrogen atmosphere.The physical properties,phase composition and microstructure of samples with N990 additions of 2.5%,3.0%,and 3.5% by mass were analyzed and compared.The results show that:(1)with N990 addition increasing,the flowability of the casting mud is improved,the demoulding and drying strengths are increased;(2)with the increase of N990 addition,the apparent porosity of the nitridized material increases,the bulk density and modulus of rupture both decrease,the content of free carbon increases,and the α-Si₃N₄ content decreases;(3)with the increase of N990 addition,because the particles agglomerating probability of carbon black increases,the uniformity of the samples become worse after nitridizing.Reaction sintering occurs between Si-C and Si-N,in addition to the continuous flocculent matrix,dense island-like β-SiC or O’-SiAlON phases also appear locally.It is thought after comprehensive analysis that the sample with 3.0% carbon black addition can better meet the need of material preparation and properties.

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