Dynamic Consolidation of TaC and Nano-YSZ Powders (POSTPRINT)

Abstract

Abstract : The high melting point of tantalum carbide (3880 deg. 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 3 microns, and grain size ranging from 0.5 to 1 micron 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 85% 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. Dynamic consolidation was also tried on nano-sized (30 - 60 nm particle size) yttria stabilized zirconia (YSZ), with the aim of obtaining nano-structured dense materials that can be further processed utilizing superplastic forming. 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.