渗硼用Na_2B_4O_7-Na_2CO_3熔盐热分析

Thermal analysis on Na_2B_4O_7-Na_2CO_3 molten salt for boronizing

对渗硼用Na2B4O7-Na2CO3熔盐体系进行DTA和TG热分析。DTA分析表明,在Na2B4O7中添加Na2CO3并没有大幅降低Na2B4O7的初晶温度。TG分析表明,Na2B4O7中添加Na2CO3能促进Na2B4O7的分解,平均每添加10%Na2CO3体系质量损失4%。Na2B4O7-Na2CO3体系的温度升高过程分别对应固体Na2B4O7的分解、渗剂熔化以及B2O2的氧化过程。硼砂熔盐渗硼最佳温度为905℃。

Na2B4O7-Na2CO3 molten salt system was analyzed by DTA and TG method of thermal analysis.The DTA results show that with addition of Na2CO3 in Na2B4O7 the initial crystallization temperature is not greatly decreased.The TG results show that the addition of Na2CO3 can promote the decomposition of Na2B4O7.When 10% of Na2CO3 is added,the mass loss of the system is 4% on average.The heating process of the molten salt system is corresponding to the decomposition of solid Na2B4O7 and the melting point of boronizing medium as well as the oxidation process of B2O2.The optimum temperature of boronizing in molten borax is 905 ℃.