铁尾矿及其反应烧结多孔陶瓷的制备与性能研究

Reaction Sintered Porous Ceramics Using Iron Tailings:Preparation and Properties

为拓展铁尾矿的资源化利用途径,本研究分别以细颗粒高硅铁尾矿、铁尾矿+石墨粉以及铁尾矿+石墨粉+碳化硅粉为原料,采用泡沫注凝成形-常压烧结、泡沫注凝成形-反应烧结和模压成形-反应烧结工艺制备了铁尾矿多孔陶瓷和三种以碳化硅为主晶相的多孔陶瓷。通过DSC-TG和XRD分析,研究了铁尾矿自身的烧结过程以及铁尾矿与石墨之间的碳热还原反应烧结过程,对比分析了四种多孔陶瓷材料的孔隙率、压缩强度、热导率等性能。结果表明,以铁尾矿为原料可制备具有较高孔隙率(87.2%)、压缩强度(1.37 MPa)和低热导率(0.036 W/(m·K))的铁尾矿多孔陶瓷,它是一种高效保温隔热材料;利用铁尾矿与石墨之间的碳热还原反应可获得碳化硅多孔陶瓷,其热导率显著提高,但强度偏低;而在原料中加入部分碳化硅,可以明显改善多孔陶瓷的压缩强度,获得具有高孔隙率(91.6%)、较高压缩强度(1.19 MPa)和热导率(0.31 W/(m·K))的碳化硅多孔陶瓷,它可作为轻质导热材料或复合相变材料的载体使用;与泡沫注凝成形工艺相比,采用模压成形工艺制备的碳化硅多孔陶瓷虽然孔隙率有所降低(79.3%),但热导率得到显著提升(1.15 W/(m·K)),同时原料和生产成本大幅降低,有利于实现产品的工业化生产。

To expand the utilization of iron tailings,four kinds of porous ceramics were prepared by foam gel-casting with pressureless sintering,foam gel-casting with reactive sintering,and mold forming with reactive sintering using fine-grained high-silicon iron tailings,iron tailings+graphite,and iron tailings+graphite+silicon carbide as raw materials,respectively.DSC-TG and XRD analysis was applied to investigate the sintering process of iron tailings and the carbothermal-reduction reaction between iron tailings and graphite.The four porous ceramics’porosities,compressive strengths,and thermal conductivities were further analyzed.The results show that the porous ceramics made only from iron tailings possesses high porosity(87.2%),compressive strength(1.37 MPa),and low thermal conductivity(0.036 W/(m·K)),meeting the requirement of thermal insulation material.Silicon carbide porous ceramics with improved thermal conductivity but a slight sacrifice of strength can be fabricated through carbothermal reduction between iron tailings and graphite.Moreover,the compressive strength of silicon carbide porous ceramics can be significantly increased by adding some silicon carbide to the raw materials.The silicon carbide porous ceramics achieved high porosity of 91.6%,high compressive strength of 1.19 MPa and thermal conductivity of 0.31 W/(m·K),which can be a guarantee of a carrier for composite phase change materials or light thermal conductive materials.Compared with foam gel-casting,the mold-forming process can significantly improve the thermal conductivity(1.15 W/(m·K))of silicon carbide porous ceramics and greatly reduce the cost of raw materials and manufacturing,which is profitable for industrialization.