The flux agents in common mould powder normally are fluoride and sodium oxide
both all produce environmental pollution. Therefore the physical properties such as melting point
viscosity
crystallizing properties and surface ten- sional force of mould powder containing flux agent B₂Os were studied. The test results showed that for the mould powder with CaO/SiO₂= 0.88 and ingredient being 37.91%CaO-43.09%SiO₂-5%A₂O₃-5%MgO-2%Li₂O-7%B₂O₃
the melting point was 909℃
the flexible melting temperature was 1160 ℃
viscosity value at 1300 ℃ was 0.4 Pa's and surface tensional force was 0.32 N/m which could meet the service requirements of concasting mould powder for normal steel grades and some special steel grades.