Low Shrinkage, Coarse-Grained Tantalum-Alumina Refractory Composites via Cold Isostatic Pressing

Alumina-tantalum composites are produced in a two-step synthesis via cold isostatic pressing (CIP) from commercially available raw materials without any addition of organic additives. The highest densification for fine-grained composites is found with a maximum pressure of 150 MPa, whereby a cyclic pressure increase or at maximum pressure showed no measurable influence. The increase of the sintering temperature from 1600 to 1700 degrees C led to a higher densification up to a relative density of 75.8%. Aggregates received by jawbreaking show a blocky morphology, rounded corners, and edges with porosities of 6.2 - 7.3%. The formation of tantalum carbide and the incorporation of oxygen into the tantalum lattice are verified during sintering. The coarse-grained composites produced from these aggregates show open porosities of 25.3 - 25.7% and shrinkage < 0.5%. Determined splitting tensile strenghts are in the range between 8.4 and 9.1 MPa.

Automated summary

This article presents a method and results of producing alumina-tantalum composites through cold isostatic pressing from commercially available raw materials. The study found that the densification of the composites can vary with different pressure and temperature conditions. The formation of tantalum carbide and the incorporation of oxygen into the tantalum lattice were also observed.