氟化物挥发对连铸保护渣熔点的影响

Influence of fluoride evaporates on melting point of molding powder for continuous casting

保护渣氟含量虽然不高,但其对炉渣的性能影响很大。由于在加热过程中存在氟化物的逸出,其对炉渣成分影响是不可忽略的,进而对炉渣性能的影响也必须引起关注。以Q195L和Q235B连铸保护渣为例,以预熔渣和相同成分的化学纯混合试样为研究对象,进行了FactSage软件理论计算、荧光光谱分析(XRF)、热重-质谱检测(TG)、'半球法'熔点检测。结果表明,在升温过程中,化学纯配制试样挥发特性表现较为明显,挥发分主要为NaF、SiF4、CaF2以及少量NaAlF4和AlF3,最终化学纯试样相对预熔渣熔点高出近180℃。其差异主要是由于氟化物的挥发特性不同,在测定中的挥发量不同,引起试样熔点测定的差异。这对研究氟化物的挥发机理以及炉渣高温性能测定与控制具有价值。

Although the fluoride content of the continuous casting mold powder is not so much,it is influence on the slag property measurement can not be ignored.Since the effect of the evaporation of the fluoride in the heating process on the change of the slag composition is not negligible,that the effect on the change of slag properties has to be concerned.Two different continuous casting molding powders,Q195 Land Q235 B,were taken as examples.By means of the calculation of FactSage software,thermogravimetric(TG)analysis and mass spectrometry analysis at a high temperature and hemispherical melting point measurement.The results showed that during the heating process,the volatile characteristics of the chemically mixed slag are more obvious.The volatiles are mainly NaF,SiF4,CaF2 and a small amount of NaAlF4 and AlF3.The melting point of the chemically pure sample is nearly 180℃higher than the pre-melting slag due to the difference in the volatilization characteristics and the amount of fluoride during the measurement,causing the difference in the melting points of the samples finally.This research is valuable for the understanding and the control of the volatilization mechanism of fluoride and slag performance at a high temperature.