Research of high-voltage consolidation of powders of refractory materials

When using powder metallurgy technology, the challenge arises of preserving the original microstructure and grain size in a compact material as a result of sintering (powder consolidation). This is particularly relevant for powders of heavy tungsten-based alloys and refractory metal carbides (tungsten, hafnium, tantalum, etc.). This problem is solved by applying approaches that utilize high-intensity, short-term, high-temperature exposure combined with mechanical pressure on the powder blank. The objective of this study is to investigate the high-voltage consolidation (HVC) process of powder materials using the developed measuring system. HVC involves simultaneously applying a short, powerful current pulse to the powder, generated by a high-voltage current pulse generator, and external mechanical pressure, generated by a pneumatic press. The measuring system included systems for recording the high-voltage current pulse and the intensity of thermal radiation from the consolidated material using pulse photometry with photodiode sensors, as well as a matching and control system. During the tests, the parameters of the high-voltage pulse current and the thermal radiation intensity of the consolidated materials were recorded under high-voltage electric pulse exposure. Optimal values for the high-voltage pulse current parameters were determined for VK20, VNZh-90, and VNM 3-2 alloys, and the structure and physical and mechanical properties of the consolidated samples were analyzed. The results can be used to improve the high-voltage consolidation methodology for refractory powder materials.