Thermodynamics of nitrogen in flux melts

本研究的目的是研究不同熔剂体系中氮气的热力学性质。熔剂成分从用于玻璃生产的酸性侧到用于炼钢的碱性侧。用化学平衡法测定了BN在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熔体中的溶解度。在石墨炉中将熔剂与BN或氮气进行平衡，分析了熔剂中的氮含量。在B2O_3中加入一定含量的碱性氧化物，提高了BN的溶解度和氮化量，然后随着添加的增加，BN的溶解度和氮化量降低。添加Al_2O_3、Y_2O_3和La_2O_3使BN的溶解度逐渐降低，且它们对BN溶解度的影响小于SiO_2。B2O_3-碱性氧化物体系中BN的溶解度随温度升高而增大，BN在熔体中的溶解热变随碱性氧化物的加入而减小。

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.