碳化硼加入量对氧化镁-氮化硅铁浇注料力学性能的影响

Effects of B_4C additions on mechanical properties of MgO-Fe-Si_3N_4 castables

以97烧结镁砂为主要原料,加入3%质量分数的氮化硅铁细粉,以硅微粉作为结合剂,研究了外加不同量碳化硼(其质量分数分别为0、0.1%、0.2%、0.3%、0.4%、0.5%)对镁质浇注料常温物理性能和高温力学性能的影响,并借助扫描电镜对浇注料的显微结构进行了分析。结果表明:随着碳化硼加入量的增加,浇注料烘干强度下降,中、高温处理后强度变大,高温抗折强度下降。原因在于碳化硼在加热过程中氧化产生液相,促进材料烧结,使得材料致密,冷态强度增大;而由于液相的产生降低了镁质材料的直接结合程度,使得高温抗折强度减小。

Effects of B4C additions （0,0.1% ,0.2% ,0.3% ,0.4% and 0.5% ） on cold physical properties and hot mechanical properties of MgO-based castables were investigated using 97 sintered magnesia as main starting material and silica fume as binder, adding 3% ferro-silicon nitride powder. The microstructure was analyzed by means of SEM. The results show that as the increase of B4C addition drying strength and hot modulus of rupture decrease,while the intermediate temperature strength and hot strength increase. The cold strength increases because B4C is oxidized producing liquid phase during heating, contributing to sintering and densifying of the material. On the other hand, HMOR decreases because direct bonding degree of magnesia based material is reduced by the liquid formation.