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

摘要： 为研究工业炭黑对复相结合碳化硅耐火材料性能的影响,以碳化硅颗粒(3～1、1~0.088 mm)与细粉(<0.088 mm)、硅粉(<0.088 mm)、工业炭黑(牌号N990)、SiO₂微粉(d₅₀=0.26 μm)和ρ-Al₂O₃微粉(d₅₀=6.0 μm)等为主要原料,采用预制浇注成型,在氮气气氛中于1 400 ℃热处理,制备了复相结合碳化硅试样。研究了N990加入量(w)分别为2.5%、3.0%、3.5%时试样的物理性能、物相组成与显微结构。结果表明:1)随N990加入量的增加,泥料的流动性改善,脱模强度及干燥强度提高。2)随N990加入量的增加,氮化后试样的显气孔率升高,体积密度和抗折强度均有下降,试样中游离C含量升高,α-Si₃N₄减少。3)随N990加入量的增加,因炭黑颗粒团聚的概率增加,氮化处理后试样显微结构的均匀性变差。Si-C和Si-N发生反应烧结,除连续的絮状基质外,局部还出现了致密孤岛状的β-SiC或O′-SiAlON相。综合分析认为,炭黑加入量(w)为3.0%的试样更能满足材料制备和性能的需要。

关键词: 工业炭黑, 复相结合碳化硅, 浇注成型, 显微结构