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

N_2气体在氮化硅陶瓷中氮在熔渣中的溶解度及溶解机理

基本信息

批准号：
09650812
负责人：
NAKASHIMA Kunihiko
金额：
$ 2.5万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

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.

用N_2-H_2气体和氮化硅陶瓷测定了氮在CaO-SiO_2-Al_2O_3和Na_2 O-CaO-SiO_2渣系中的溶解度。对淬火渣进行了维氏硬度测试和XPS分析。在一定氧分压下，用N_2-H_2气体与渣的平衡关系测定的氮容量随SiO_2含量的增加而降低。这一结果表明，氮通过氧离子与氮之间的交换反应溶解在渣中。另一方面，氮化硅陶瓷和炉渣之间的平衡的氮化物容量比气-渣平衡的氮化物容量大10^2至10^4倍。虽然氮化硅的氮化容量是在氮化硅分解的假设下计算的，但与气渣平衡计算的结果不一致。氮化硅陶瓷溶解氮的机理与氮气溶解氮的机理不同，氮化硅溶解后凝固渣的维氏硬度随SiO_2含量的增加而降低，这与SiO_2对氮溶解度的影响是一致的。这表明氮化硅的溶解促进了渣中网络的形成，并推测是Si-N（或Al-N）与氧化物形成复杂网络的过程。XPS分析的结果支持这些估计。