熔融渗硅对石墨氧化行为的影响

Influence of Silicon Infiltration on Oxidation Behavior of Graphite

分别在500℃、700℃、900℃及1 100℃空气条件下,对石墨及渗硅石墨进行氧化实验,以分析熔融渗硅对等静压石墨氧化行为的影响。采用扫描电镜(SEM)分析了样品表面及内部形貌,通过压汞法表征了样品的孔隙结构,并对材料的力学性能进行了测试分析。结果表明:500℃条件下,石墨和渗硅石墨均未发生明显的氧化失重现象;温度为700℃时,石墨的氧化失重率随时间延长明显增加,而该温度下渗硅石墨的氧化失重率变化较小。而且,渗硅石墨在700℃时仍能保持较好的强度,而此温度下,石墨随氧化时间的延长,强度明显降低,甚至被氧化成粉末状。因此,熔融渗硅在提高材料抗氧化性能的同时能够显著提升材料的强度。

Graphite with/without silicon infiltration were oxidized at temperatures of 500 ℃, 700 ℃, 900 ℃ and 1 100 ℃, respectively, and the influence of silicon infiltration on the oxidation behavior of isostatic graphite was studied. SEM was adopted to characterize the surface and interior morphology. The pore structure of graphite was characterized by mercury intrusion porosimetry, and the mechanical properties of samples were measured. Results show that there is no obvious oxidative mass loss of samples at the temperature of 500 ℃. At the temperature of 700 ℃,the mass loss of graphite increases with the oxidation time, while no obvious mass loss is detected for the graphite with silicon infiltration. Moreover, the graphite with silicon infiltration maintains the high strength after oxidized at 700 ℃, but the strength of graphite without silicon infiltration significantly decreases and the bulk graphite even becomes powders. Therefore, the silicon infiltration can significantly increase the strength of graphite while improving its oxidation resistance.