Abstract: To explore the reuse of iron tailings,the porous silicon carbide ceramic materials were prepared by carbothermal reduction with iron tailings and anthracite as raw materials.The effects of the molar ratio of C to SiO₂ (3∶1,4∶1,5∶1 and 6∶1) and the heat treatment temperature (1 200,1 300,1 400 and 1 500 ℃) on the microstructure,mechanical properties,and thermal conductivity of the porous silicon carbide ceramic materials were studied.The results show that the main crystalline phase of the porous silicon carbide ceramic materials is β-SiC,and the secondary crystalline phases are Fe₅Si₃ and Fe₃Si;with the increasing heat treatment temperature and the molar ratio of C to SiO₂,the carbothermal reduction reaction tends to be complete,the β-SiC content increases gradually,the bulk density and cold compressive strength decrease,the apparent porosity increases and the thermal conductivity decreases.When the heat treatment temperature is 1 500 ℃ and the molar ratio of C to SiO₂ is 6∶1,the optimal properties can be achieved:the bulk density of 1.25 g·cm^-3,the apparent porosity of 62.3%,the cold compressive strength of 35.0 MPa,and the thermal conductivity of 0.150 W·m^-1·K^-1 at 800 ℃.

Key words: iron tailings, anthracite, silicon carbide ceramics, carbothermal reduction, thermal conductivity

摘要： 为了探究铁尾矿的再利用,以铁尾矿和无烟煤为原料,经碳热还原反应制备了碳化硅多孔陶瓷试样,研究了C与SiO₂物质的量比(C和SiO₂物质的量比分别为3∶1、 4∶1、5∶1和6∶1)及热处理温度(1 200、1 300、1 400和1 500 ℃)对碳化硅多孔陶瓷试样显微结构、力学性能和热导率的影响。结果表明:碳化硅多孔陶瓷主晶相为β-SiC,次晶相为Fe₅Si₃和Fe₃Si。随着热处理温度升高,C与SiO₂物质的量比增加,碳热还原反应越充分,β-SiC相含量逐渐增加,试样的体积密度和常温耐压强度降低,显气孔率增加,热导率降低。当热处理温度为1 500 ℃,C与SiO₂物质的量比为6∶1时,试样的体积密度为1.25 g·cm^-3,显气孔率为62.3%,常温耐压强度为35.0 MPa,800 ℃时热导率为0.150 W·m^-1·K^-1,综合性能最佳。

关键词: 铁尾矿, 无烟煤, 碳化硅陶瓷, 碳热还原, 热导率