1 Experimental In order to compare the fusing behaviour of two kinds of fluxes,chemically pure reagents were used to compound fluxes which were carbon-free.The ingre- dients of fiuxes and the particle size are shown in Table I. Table 1 The ingredient of fluxes and the particle size Composition Composition,% Particle size type SiO2 CaO Al2O3 CaF Na2 CO3 Fe2Os mesh mixed <10055-75,75- 50 40 10 100,100-150, prefused 150-200,<200 mixed <10055-75,75- Il 44 35.5610 10 100,100-150, prefused 150-200,<200 III mixed 4444 35.5610 10 <100 IV mixed 52.78 42.2210 5 <100 At the same lime,an investigation of the fusion behaviour of prefused powder fluxes used in industrial production has been shown as follow:composition(%)- Si02,3982;Ca0,37.47;Mg0,318;Fe20g,331;A1,0g,9.31;Na20,2.23: K20,0.57;size range of fluxes(mm):0.71~1.4;1.4~3.0;3.0~5.0;5~7; 7~11.8. The drip-melt method was adopted to measure the "point"melting behaviour of flux in the experiment.Because the heat capacity of samples were much less than that of furnace,it was supposed that the samples were so small (63mmx 3mm)that they had the same temperature of the furnace and the temperature homogenization of the samples could be reached in a twinkling,ie.,the effect of interior heat transfer of sample on its melting behavior could be neglected. The precedure of experiments was as follows: (1)Heating the furnace up to 1000C; (2)Charging the sampling into the furnace; (3)Keeping the heating rate in the range of 5.5-6.8C/min; (4)Observing the change of sample height with the increase of furnace tempe- rature; (5)Recording the starting melting temperature toto finish melting tempe- rature (1.)and the rate (dHi/dti)during melting (shown in Figl.) 517纽 从 ， ， 注 改 一 · 工 里以 又 王 认 · 里 卜 、 。 ， 。 。 ，、 必 又 ， ‘ ， ‘ 马 匕一 ‘ 口 呀匀 口 口 以 』‘ 一 ， ， 一 ， 一 ， 一 ， ， 一 ， 一 ， …吮丫刀﹄ 往口 ，土 八 任号只，哇曰山月 气 吸‘ 土 。 ， 主 士 。 几 。 。 、丫 。 二 一 ， · ， ， 。 ， ， 。 ， 一 ， · 一 一 一 。 一 一 。 。 一 “ ’， 从 。 ， 价 玉 一 ， ， 一 · ， · 五 从 一 从 一 “ 。 。 一 皿 飞 。 、 、 主 一