1.0 1.0 0.8 0.8 0. 0.6 0.4 0.4 0.2 0.2 0 .1140 12201300 1220 1260 1300 1340 t,℃ t,℃ Fig.3 The melting characteristics of Fig,4 The effect of CaF2 additive prefused type (A)and simply on the melting characteristics mixed type (B)fluxes based of prefused (A)and simply on SiO-CaO-Al2O3 flux system mixed (B)fluxes (CaF2 =10%) Experimental results for the prefused powder flux (A),the starting melting temperature was about 1245C,and finishing melting temperature was 1285C,so the range of melting temperature was 40C.For the simply mixed powder flux (B),these three values were about 1300C,1340C and 40C respectively.That is,both of them had same fusion rate.This conclusion indicated that the melting behaviour of them could be kept as the same unless the temperature of hot metal with using simply mixed flux was 60C higher than that with using prefused flux.And it was predicted that the difference of melting behaviour between them should vary with the change of chemical compositions and particle size of fluxes. The prefused fluxes had a strong tendency to form glass phase themselves after re-melted.This glass phase was homogeneous (photograph 1.A).But the tendency to form homogeneous glass phase for the melted simply mixed fluxes were related to the compositions and componenls of raw materials.Excepted few cases,the tendency to form glass for most of the simply mixed fluxes were not completed because the small solid particles were often surrounded by a layer of two-phase mixture (photograph I.B). 2.2 Effect of Additives The melting curves of fluxes in which CaF2 was added as additive to the above basic composition of flux system were shown in Fig.4.for prefused and simply mixed fluxes. The results showed that,for both kinds of fluxes,the melting temperature of prefused flux was lower than that of simply mixed flux,but the difference between them slightly decreased. 519从 一 、 、 甲 、 架卜 气 、 一 ，、 、 、一 口川》 目 之 ‘ ︸ 卜九 一二衬加。 一 一二词切。 欢 、 、 人、 、、 、 丫 勺 ” 入 ‘ 义 一 、日 】 之心 。 、 亡 ， “ ， ℃ 汽 气 、 ‘ 卜 万 。 卜 卜 一 一 。 ， “ ， “ ， 五 扭 ， “ ， ” ，， 七 升 。 主 至 “ 研 一 皿 。 一 · · · 一 。 ， 一 义 。 从 从· 甲 · 一 从 ， ， ， 五