Thermodynamics of nitrogen in flux melts

本研究的目的是研究不同通量系统中氮的热力学性质。熔剂的组成从用于玻璃生产的酸性侧到用于炼钢的碱性侧不等。用化学平衡法测定了B_2O_3-Li_2O、B_2O_3-Na_2O、B_2O_3-Rb_2O、B_2O_3-Cs_2O、B_2O_3-CaO、B_2O_3-BaO、B_2O_3-Al_2O_3、B_2O_3-Y_2O_3和B_2O_3-La_2O_3熔体中BN的溶解度，温度范围为1273 ~ 1823K。在石墨坩埚中用BN或氮气平衡熔剂，分析了熔剂中的氮含量。在B_2O_3中加入一定含量的碱性氧化物，BN的溶解度和氮化容量增加，随着添加量的增加，BN的溶解度和氮化容量减小。Al_2O_3、Y_2O_3和La_2O_3的加入使BN的溶解度逐渐降低，其降低BN溶解度的作用小于SiO_2。b_2o_3 -碱性氧化物体系中BN的溶解度随温度升高而升高，BN在熔体中溶解的焓变随碱性氧化物的加入而减小。研究了B_2O_3熔体中氮的热力学。

The purpose of present study is to investigate the thermodynamic properties of nitrogen in the various flux systems. The flux composition ranged from acidic side which is used in the glass production to basic side used for the steelmaking. The solubilities of BN in the B_2O_3-Li_2O, B_2O_3-Na_2O, B_2O_3-Rb_2O, B_2O_3-Cs_2O, B_2O_3-CaO, B_2O_3-BaO, B_2O_3-Al_2O_3, B_2O_3-Y_2O_3 and B_2O_3-La_2O_3 melts have been measured at temperatures ranging from 1273 to 1823K by using a chemical equilibration technique. A molten flux was equilibrated with BN or nitrogen gas in a graphite crucible and the nitrogen content in flux was analyzed.The addition of basic oxides to B_2O_3 up to a certain content increases the BN solubility and nitride capacity, and then decreases it as they are added further. The BN solubility gradually decreases by the addition of Al_2O_3, Y_2O_3 and La_2O_3 and their effect to decrease the BN solubility is smaller than that Of SiO_2. The BN solubilities in the B_2O_3-basic oxide systems increase with temperature and the enthalpy change of dissolution of BN into melts decreases with the addition of basic oxides.The thermodynamics of nitrogen in B_2O_3 melts was investigated in this study.