自蔓延合成Al_4SiC_4和B_4C及其在含碳耐火材料中的应用

Self-propagating high-temperature synthesis of Al_4SiC_4 and B4C and their application in carbon-containing refractories

以金属铝粉、硅粉、炭黑或石墨为原料,采用自蔓延化学炉法制备了Al4SiC4粉体,并将其添加到以板状刚玉、电熔刚玉、氧化铝微粉和石墨为主要原料的铝碳材料中,经混合、150 MPa冷等静压成型后于1 100℃保温5 h氮气保护烧成,研究其对铝碳材料的物理性能、抗氧化性能和抗水化性能的影响;以B2O3、金属Mg、炭黑和超细石墨为主要原料,采用自蔓延镁热还原法制备了B4C粉体,并将自蔓延产物添加到以电熔镁砂和超细石墨为主要原料的低碳镁碳砖中,经混合、200 MPa干压成型后于1 600℃5 h埋炭烧成,研究其对镁碳材料的物理性能、抗氧化性能的影响。结果表明:1)以Al、Si、炭黑或石墨为原料可以合成纯度高、不含Al4C3相的Al4 SiC4粉体;添加7%Al4 SiC4粉体的铝碳材料具有良好的常温和高温性能,具有良好的抗氧化性和抗水化性能。2)以B2O3、Mg和炭黑为原料可以合成晶粒细小、活性较高的B4C粉体;添加B4C复合粉体的低碳镁碳砖具有良好的常温性能和热态强度,其抗氧化性能优于添加市售B4C和金属Al粉的试样。

Al4SiC4 powder was synthesized by chemical oven self-propagating high-temperature synthesis （COSHS） using Al ,Si ,carbon black or graphite as main starting materials. Alumina-graphite materials were prepared using tabular corundum, fused corundum, alumina micropowder, graphite and the prepared Al4SiC4 pow- der,mixing,cold isostatic pressing （CIP） under 150 MPa,and firing at 1 100 ℃ for 5 h in nitrogen. Effects of Al4SiC4 on physical properties,oxidation resistance and hydration resistance were investigated. B4C powder was synthesized by self-propagating magnesiothermic reduction synthesis （SMRS） using B2O3, Mg, carbon black and superfine graphite as main starting materials. Low carbon magnesia carbon bricks were prepared using fused magnesite,superfine graphite and prepared B4C, mixing,dry pressing at 200 MPa, and carbon-embedded firing at 1 600 ℃ for 5 h. Influences of B4C on physical properties and oxidation resistance were investigated. The results show that： （ 1 ） high purity Al4SiC4 powder without Al4C3 phase is synthesized using AI,Si and carbon black or graphite as starting materials;the alumina-graphite materials synthesized with 7% Al4SiC4 powder have good properties at both room and high temperatures,excellent oxidation resistance and hydration resistance; （2）B4C powder with fine grains and higher activity is synthesized using B2O3 ,Mg and carbon black as starting materials;the low carbon MgO-C bricks with B4C composite powder, featured with excellent cold properties and high hot strength, show better oxidation resist- ance than that with additive of commercial B4C and Al powders.