中间包镁质干式料用结合剂的研究

Binders of magnesia based dry vibration mix for tundish

首先将电熔镁砂(≤0.088 mm)分别与低温结合剂(分别为沥青、蔗糖、石蜡、松香、酚醛树脂)和中温结合剂(分别为三聚磷酸钠、九水硅酸钠、六水氯化镁、硼酸、十水硼砂和硼酸盐玻璃)按95∶5的质量比混练均匀,以120 MPa的压力干压成型为36 mm×36 mm的试样,分别在300℃2 h、1 000℃3 h、1 450℃3 h、1 500℃3 h和1 600℃3 h条件下热处理后测量其显气孔率、体积密度和耐压强度,以评价这些结合剂的结合性能和促烧结性能,并评价了其环保性;然后,在上述试验的基础上分别采用沥青-硼酸盐玻璃、松香-硼酸盐玻璃和酚醛树脂-硼酸盐玻璃3种复合结合剂按镁质干式料的配方制备成镁质干式料试样,分别在200℃2 h、1 100℃3 h和1 500℃3 h条件下热处理,测量试样热处理后的永久线变化率、显气孔率、体积密度和耐压强度等常温物理性能。结果表明:采用酚醛树脂、沥青和松香为结合剂时,镁质材料300℃2 h热处理后的耐压强度较高;而采用硼酸、十水硼砂和硼酸盐玻璃为结合剂时,镁质材料1 000℃3 h热处理后的耐压强度较高,硼酸和硼酸盐玻璃能明显促进镁质材料的高温烧结;使用5%松香-4%硼酸盐玻璃作为复合结合剂制备的镁质干式料具有较好的常温物理性能和环境友好性。

Mixing 95% fused magnesia （ ≤0.088 mm） with 5% low temperature binders （pitch, sucrose, mineral wax, rosin and phenolic resin respectively） or middle temperature binders （sodium tripolyphosphate, Na2SiO3 · 9H20,MgC12 · 6H20, boric acid, borax and boroate glass respectively）,the specimens with the size of φ36 mm ×36 mm were prepared by dry pressing under 120 MPa. The AP,BD and CCS of specimens fired at 300 ℃ for 2 h,1 000 ℃ for 3 h, 1 450 ℃ for 3 h,1 500 ℃ for 3 h, 1 600 ℃ for 3 h respectively were determined to estimate the binding ability and sintering promoting of these binders. Based on the above experiment,three kinds of compound binders （pitch-borate glass, rosin -borate glass and phenolic resin -borate glass） were used to prepare magnesia based dry vibration mix. The PLC,AP,BD and CCS of specimens fired at 200 ℃ for 2 h, 1 100 ℃for 3 h, 1 500 ℃for 3 h respectively were tested. The experimental results show that： （1）The CCS of magnesia based material bonded by phenolic resin,pitch and rosin fired at 300 ℃ for 2 h is high;Higher CCS is also obtained for magnesia based material bonded by boric acid,borax decahydrate and borate glass fired at 1 000 ℃for 3 h, boric acid and borate glass can promote the sintering of magnesia refractories at high temperature apparently. （2）The magnesia based dry vibration mix with 5% rosin and 4% borate glass as binder has better physical properties at room temperature and is en- vironmental friendly.