不烧Al-Si复合低碳Al_2O_3-β-SiAlON材料的抗氧化性能

Oxidation resistance of unfired Al-Si-containing low carbon Al_2O_3-β-SiAlON materials

采用大试样高温热重分析仪研究了不烧Al-Si复合低碳Al2O3-β-SiAlON材料（MAC-F）的抗氧化性,并与Al-Si复合不烧铝碳滑板材料（MAC-S）进行了比较。结果表明（1）两种材料在250-1100℃氧化时的质量变化规律相似,在500℃以前均处于质量损失状态;从500℃开始试样处于质量增加状态,500-1100℃之间两种材料质量变化率的增加量差别不大;1100℃以上材料MAC-S的质量变化率的增加量明显提高,而材料MAC-F质量变化率的增加量稍有降低。（2）1500℃氧化后,材料MAC-F质量增加率明显低于材料MAC-S的,氧化层很薄,厚度仅0.5mm。材料MAC-F的氧化层中有较多的短柱状莫来石晶体,均匀地分布在刚玉骨架结构的空隙中,形成致密的结构,对氧气进入材料的内部起到了阻碍作用。其氧化层表面覆盖着一层由莫来石和少量玻璃相组成的光滑薄膜,更有效阻碍了氧气向内部的渗透。因此,材料MAC-F与材料MAC-S相比,抗氧化性能更为优异。

The oxidation resistance of unfired Al-Si-containing low carbon Al2O3-β-SiAlON material（MAC-F）was investigated using high temperature thermogravimetric analyzer for large sized specimens,and the oxidation resistance of this material is compared with unfired Al-Si-containing Al2O3-C material（MAC-S）.The results show that：（1）The mass changes of two materials were similar at 250~1 500 ℃.The masses decreased below 500 ℃,and began to increase at 500 ℃.The increases of mass change rate of two materials were simila at 500 ～100℃. Above 1100℃,the increase of mass change rate of MAC -S greatly increased, and that of MAC -F slightly decreased. （2）After oxidized at 1500℃, MAC -F had the obviously lower mass increasing rate than MAC -S,and the oxidized layer was very thin （only 0.5 mm）. Much short column mullite crystals in the oxidized layer filling in the interstices of corundum skeleton structure in the oxidation layer of MAC.-F forming dense structure, and a thin film composed of mullite and a little glass phase covering the oxidizing surface, which prevented the penetration of oxygen and retarded the oxidation. So the oxidation resistance of MAC -F was better than that of MAC -S.