氮化硅-莫来石复合材料的制备

PREPARATION OF SILICON NITRIDE-MULLITE COMPOSITE

以莫来石、氮化硅为主要原料,铝酸钙水泥、硅微粉为结合系统,制备了氮化硅-莫来石复合材料,并与莫来石材料进行了对比。试样自然干燥24h脱模后,再经110℃烘干24h,分别在空气气氛下于1000℃、1300℃和1500℃热处理3h。检测各温度热处理后试样的体积密度(B.D)、常温抗折强度(M.O.R)、常温耐压强度(C.C.S)以及试样的热膨胀系数、耐磨性能和抗热震性能。结果表明,经过1000℃、1300℃和1500℃热处理后,氮化硅-莫来石复合材料的常温抗折强度和常温耐压强度均大于莫来石材料的常温抗折强度和常温耐压强度。在本实验条件下,在莫来石基材料中添加氮化硅并不能提高材料的耐磨性能。在1250℃～1400℃温度之间,氮化硅-莫来石复合材料的热膨胀系数小于莫来石材料的热膨胀系数。氮化硅-莫来石复合材料试样热震后的耐压强度大于莫来石材料试样热震后的耐压强度,但耐压强度保持率小于莫来石材料。

Silicon nitride-mullite composite was prepared with mullite and silicon nitride as raw materials,calcium aluminate cement and silica flour as binders,and silicon nitride-mullite composite was compared with mullite material.After 24h curing in mould and another 24h curing at 110℃ after demoulding,the specimens were heat treated in atmosphere at 1000℃,1300℃ and 1500℃ for 3h.The bulk density,modulus of rupture and cold crushing strength,thermal expansion coefficient,abrasion resistance and thermal shock resistance were examined.The results show that modulus of rupture and cold crushing strength of silicon nitride-mullite composite were better than those of mullite material after firing at 1000℃,1300℃ and 1500℃.Adding silicon nitride into mullite based material could not improve the abrasion resistance of the materimals under this test condition.The thermal expansion coefficient of silicon nitride-mullite composite was lower than that of mullite material with the firing temperature rising from 1250 to 1400℃.The cold crushing strength of silicon nitride-mullite composite after thermal shocking was better than that of mullite material,but conservation rate of cold crushing strength was lower than that of mullite material.