resumo
The processing of submicrometer hardmetal grades using water and ethanol was compared. Powder dispersion was first studied in terms of electrokinetic experiments. Higher repulsive charges are generated in powders surfaces when immersed in water, which tends to decrease suspensions viscosity and to improve milling efficiency. Using water, suspensions with higher solids loading, shorter milling times can be achieved without affecting the microstructural homogeneity. Sintered samples with Co contents of 5.5 and 3.5 wt% were also prepared using both liquids. Higher quality microstructures in terms of grain size distribution, Co dispersion, porosity, and fracture toughness were obtained in water milling. This better Co distribution results in significant differences in terms of sintering behavior. Water processing of hardmetals can therefore bring substantial improvements to the production of these submicrometer grades with low Co contents, known for their processing difficulties. On the other hand, water technology is also environmental friendlier, requires lower investments related with equipment safety and maintenance costs, and hence it is a very promising step toward hardmetal green fabrication.
categoria
Materials Science
autores
Soares, E; Malheiros, LF; Sacramento, J; Valente, MA; Oliveira, FJ
nossos autores
Filipe José Alves de Oliveira
Investigador Principalagradecimentos
This work was financially supported by Durit and Portuguese Science Foundation (FCT) under grant BDE15663.