Solubility and dissolution mechanism of nitrogen in molten slags by N_2 gas ro silicon nitride ceramics.

用N_2-H_2气体或氮化硅陶瓷测定了氮在CaO-SiO_2-Al_2O_3和Na_2O-CaO-SiO_2渣中的溶解度。此外，还测量了淬火渣的维氏硬度和XPS分析。在此基础上，讨论了氮气在炉渣中的溶解机理。在一定氧分压下，氮化物容量随SiO_2含量的增加而降低。这一结果表明，氮是通过氧离子与氮之间的交换反应溶解在炉渣中的。而氮化硅陶瓷与炉渣之间的平衡氮化容量是气渣平衡的10^2~10^4倍。虽然在氮化硅分解的假设下计算了氮化硅的容量，但与气渣平衡计算的结果不一致。由此可见，氮化硅陶瓷溶解氮气的机理与氮气不同。氮化硅溶解后的固化渣的维氏硬度随着SiO_2含量的增加而降低，这一趋势与SiO_2对氮气溶解度的影响是一致的。这表明氮化硅的溶解促进了炉渣中网络的形成，而氮化硅的溶解可能是由于Si-N(或Al-N)与氧化物之间形成了复杂的网络。XPS分析的结果支持这些估计。

The solubilities of nitrogen in CaO-SiO_2-AI_2O_3 and Na_2O-CaO-SiO_2 slags were measured using N_2-H_2 gas or silicon nitride ceramics. Moreover Vickers hardness and XPS analysis of the quenched slags was measured. Based on these results, the dissolution mechanism of nitrogen into the slags was discussed.The nitride capacity measured by an equilibrium between N_2-H_2 gas and slag under a given partial pressure of oxygen decreased with increasing SiO_2 content. This result suggested that nitrogen dissolved in the slags by exchanging reaction between oxygen ion and nitrogen. On the other hand, the nitride capacity by an equilibrium between silicon nitride ceramics and slag was 10^2 to 10^4 times larger than that from gas-slag equilibrium. Although the nitride capacity was calculated assuming that silicon nitride decomposed, it was not in agreement with that from gas-slag equilibrium. Therefore it was estimated that the dissolution mechanism of nitrogen using silicon nitride ceramics was different from that obtained by nitrogen gas.Vickers hardness of the solidified slag after silicon nitride dissolution decreased with increasing SiO_2 content and this tendency was the same as the influence of silica on nitrogen solubility. This suggested that network formation in the slag was strengthened by the dissolution of silicon nitride, which was estimated to proceed with the formation of complex network between Si-N(or Al-N) and oxide. The results of XPS analysis supported these estimations.