熔盐化学法原位合成难熔金属合金粉末机理与应用性研究

Refractory intermetallics have received considerable attention as new high temperature structural materials, and it was researched as one of the hotspot. The chemical reaction in molten salts was a kind new direct synthesized method, duo to its short process, low energy consumption and excellent powder products. Through extensive researches, it was found that the key technique to control precisely the synthesis of excellent powder is the structure of the oxides molten salt reaction system, which limits the application prospect of molten salt method. For the project, the solubility and structure on oxides in the NaCl-CaCl2 system will be researched, and the dissolution mechanism of oxides will be discussed. The mechanism of the metallothermics to synthesize refractory intermetallics powder in the oxides molten salt reaction system will be studied to precisely control the phase composition of powder products. That will be a breakthrough in technology and theory of in-situ chemosynthesis. Take the tungsten intermetallics powder synthesis as an example, the process, mechanism and application of metallothermics in the molten salt will be researched. The successful development of the new processes to synthesize refractory intermetallics powder and the establishment of the dissolution-reduction mechanism, will point to a new direction on precise controlling to synthesize refractory intermetallics powder, and break a new way on recycling utilization refractory metal, too. The process has broad application prospects, and it has great significance for the strategy on improving the country's national strength.

难熔金属间化合物材料作为新型高温结构材料倍受世人关注，成为目前研究新型高温结构材料的热点之一。熔盐化学法作为一种新型的制备方法，实现了短流程、低能耗制备出优异的难熔金属合金粉末。经大量研究发现，氧化物反应体系的熔盐结构是制约精确控制合成优异粉末的技术关键，严重影响熔盐化学法的应用前景。本项目主要研究NaCl-CaCl2中氧化物的溶解度及熔盐结构，探讨氧化物的溶解机理；研究氧化混合物被还原合成难熔金属间化合物粉末的机理，实现难熔金属间化合物物相成分精确控制，实现技术和理论的突破。以合成钨金属间化合物粉末为例进行机理应用研究，获得此工艺及机理的普遍适用性规律。熔盐化学新工艺研发成功及溶解-还原合成机理的建立，为精确控制合成难熔金属间化合物粉末材料指明了一个新的制备方向，也为难熔金属回收高效利用开辟了一个新途径，此工艺具有广阔的应用前景，对提高国家国力的战略具有重要意义。

难熔金属间化合物材料作为新型高温结构材料倍受世人关注，成为目前研究新型高温结构材料的热点之一。熔盐化学法是短流程、低能耗制备难熔金属合金粉末的一种新方法，其反应体系熔盐结构是制约产品性能精确控制的关键。本项目研究了Nb2O5和Al2O3氧化物在NaCl-CaCl2中的溶解行为及其机理，经TG-DSC和XRD数据说明Nb2O5在NaCl-CaCl2中能够溶解并以铌酸根离子存在，同时具有一定的溶解度；而Al2O3在NaCl-CaCl2中不能溶解。同时还研究了Nb2O5-Al2O3氧化混合物在NaCl-CaCl2中溶解-还原合成机理，分析发现氧化混合物在熔盐介质以及相互作用下，可以溶解并以铌酸根离子和铝酸根离子存在，形成均相反应体系，经过钠热还原后获得铌铝合金及其金属间化合物粉末。最后，本项目对熔盐化学工艺应用到废硬质合金回收再生领域进行了研究，研发出空气中氧化-熔盐化学回收再生工艺和熔盐中氧化-原位还原合成回收再生工艺，这两条新工艺的研发成功，不仅为废硬质合金回收并高效利用开辟了新领域、新途径，而且对熔盐化学工艺的溶解-还原合成机理的普遍应用提供了实验数据和理论支持。同时，熔盐化学工艺应用到钒钛冶金领域，短流程冶炼钒钛合金新工艺的研发成功，不仅为钒钛资源综合利用提供新方向，而且验证了熔盐化学工艺应用的普遍性和广泛性。