负压浇注对刚玉浇注料性能的影响

Influence of vacuum casting on property of corundum castables

按板状刚玉颗粒70%(w)、板状刚玉细粉和氧化铝微粉26%(w)、纯铝酸钙水泥3%(w)和减水剂1%(w),加适量水配制成刚玉浇注料,搅拌均匀后倒入真空浇注设备的模具中,分别于真空度为0、-0.03、-0.06和-0.09MPa的时刻开始振动浇注成型,振动时继续抽真空2min,试样经养护、烘干和1500℃3h热处理后,研究负压浇注对刚玉浇注料物理性能、抗热震性和抗渣性的影响,并借助压汞仪测定试样孔径分布,采用SEM观察试样断口形貌。结果表明:与常压浇注的试样相比,负压浇注可使试样中的气孔直径从10～20μm降到0.5～2μm,使试样结构更加致密,从而提高其机械强度和抗渣侵蚀性;负压浇注对试样的抗热震性略有负面影响,但负压浇注的试样热震后强度仍高于常压浇注的;在真空度为-0.03～-0.06MPa之间开始振动浇注时,得到的浇注料试样综合性能最好。

Corundum castables specimens were prepared by stirring 70 wt% tabular corundum grains,26 wt% tabular corundum fines and ultra-fines alumina,3 wt% pure calcium aluminate cement, i wt% water-reducing agent and appropriate amount of water, pouring in the mold of vacuum casting equipment, beginning to vibrate when the vacuum degree reached 0, -0.03, -0.06, -0.09 MPa, respectively,and vacuumizing for 2 minutes while vibration. The specimens were cured ,dried and fired at 1500℃ for 3 h. Influences of vacuum casting on physical properties, thermal shock resistance and slag resistance of the specimens were studied. The pore size distribution and fracture appearance of the specimens were investigated with mercury porosimeter and SEM, respectively. The results showed that： （1）Compared with the normal pressure casting specimens,vacuum casting decreased the pore diameter of the specimens from 10 -20μm to 0, 5 -2μm, made the specimens denser,enhanced the mechanical strength and the slag corrosion resistance; （2）The thermal shock resistance of the castables slightly deteriorated, but the residual strength after thermal shock of the vacuum casting specimen was still higher than that of the normal pressure casting specimens; （3）The specimen casted at between -0.03 MPa and -0.06 MPa had the best performance.