碳化钽粉末的爆炸成形方法

Dynamic Consolidation of TaC Powders

碳化钽熔点为3880℃,是地球上第二高熔点的物质.其抗腐蚀性能优越,在航空领域有广阔的应用空间.但是传统的材料加工方法,比如热压或者热等静压,会导致晶粒快速长大而得到低的断裂韧性.本文利用爆破方法来克服晶粒长大问题,得到强度和断裂韧性高的碳化钽.碳化钽颗粒直径小于3μm,组成晶粒为0.5～1μm,填充到双层钢管进行爆炸处理.在钢管的底部发现碳化钽试样几乎达到理论密度,但是该区域裂纹较多,硬度测得为15 GPa,和文献报道的碳化钽理论硬度相同.在钢管的中部的试样密度为理论密度的85%,这个区域没有发现裂纹.之后的旨在提高试样密度热处理中,发现了其烧结特征发生改善.经分析是因为爆炸使碳化钽粉末的颗粒内部产生内应力,而使其扩散激活能降低的结果.

The high melting point of TaC(3880 C),second amongst all known materials,along with good corrosion resistance makes TaC a potential candidate for Air Force applications.However,traditional methods of manufacturing,such as hot pressing or HIP-ing,give rise to rapid grain growth and low fracture toughness.In this work,we have utilized dynamic consolidation technique to overcome the grain growth problem,and thereby obtain stronger and more fracture resistant TaC.TaC powders of size less than 3μm,and grain size ranging from 0.5 to 1μm,were packed in double-tube steel vessels and subjected to explosive consolidation.The double-tube configuration was selected to increase pulse duration and aid plasticity induced consolidation.Almost full densification was observed near one end of the cylindrical containers,but this region also was accompanied with cracking.The hardness approached 15 GPa,similar to hardness values reported in the literature for dense TaC.In the central regions of the cylinders,the density was approximately 83% of theoretical density.However,the region was free of cracks.Post heat treatments aimed at achieving full density will be discussed in the context of improved sinterability of shock treated powders.Our results show that indeed fully dense material may be fabricated by this route,and our technique appears to overcome some of the major problems associated with consolidation of nano-materials.