无氟结晶器保护渣结晶矿相研究

Study on crystalline phases of free fluoride mould powder

实验室自制无氟渣,其熔化温度为1034℃,结晶温度为950℃,满足裂纹敏感性弱的钢种高速连铸的要求,并利用AX IOPLAN万能显微镜和PH ILPS PW 1700型X射线衍射仪对该无氟实验渣的结晶矿相进行了研究分析,结果表明,结晶矿相为黄长石,实际上是铝黄长石(Ca2A 2lS iO7)、镁黄长石(Ca2M gS i2O7)和钠黄长石(N aCaA lS i2O7)的固溶体,其中以镁黄长石为主,通过调整渣膜中黄长石的析晶率,同样可控制结晶器与坯壳间的传热,从而解决无氟渣冷凝过程中因不能析出枪晶石而无法控制传热的问题。

The free fluoride mould powder sample was made in the laboratory. Its melting temperature was 1034℃ and crystalline temperature was 950℃, so it could meet high speed continuous casting of steel with low craw sensitivity. In addition, the crystalline phase of the free fluoride experimental mould powder was studied and analyzed by AXIOPLAN multiple purpose microscope and PHILPS PW1700 x-ray diffraction instrument. The results show that the crystalline phase is melilite which is the solid solution of aluminiummelilite（Ca2Al2SiO7）, akermanite（Ca2MgSi2O7） and sodiummelilite （NaCaAlSi2O7） in fact, akermanite（Ca2MgSi2O7）is a dominant ingredient in the solid solution. So heat transfer between the mould and the shell of the strand can be controlled by regulating the crystallization rate of melilite, the problem is solved that the heat flux couldn＇t be controlled because of no cuspidine freezing out from liquid free fluoride mold fluxes during coolling.