Binders of magnesia based dry vibration mix for tundish

Mixing 95% fused magnesia ( [less-than or equal to] 0.088 mm) with 5% low temperature binders (pitch, sucrose, mineral wax, rosin and phenolic resin respectively) or middle temperature binders (sodium tripolyphosphate, Na2SiO3·9H2O, MgCl2·6H2O, 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°C for 2 h, 1000°C for 3 h, 1450°C for 3 h, 1500°C for 3 h, 1600°C 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°C for 2 h, 1100°C for 3 h, 1500°C 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°C 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 1000°C 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 environmental friendly.