Titanium foam has been the focus of special attention for its specific structure and potential applications in purification, catalyst substrate, heat exchanger, biomaterial, aerospace and naval industries. However, the liquid-state foaming techniques are difficult to use in fabricating Ti foam because of its high melting temperature and strong chemical reactivity with atmospheric gases. Here, the fabrication of Ti foams via the powder metallurgy route was carried out by utilizing both magnesium powders and magnesium particles as spacer holders, and Ti powders as matrix metal. The green compacts containing Ti powder, Mg powder and Mg particles were heated to a certain temperature to remove the magnesium and obtain the Ti foam. The results show that the porosities of the obtained Ti foam are about 35–65%, and Young’s modulus and yield strength are found to be in the ranges of 22–126 MPa and 0.063–1.18 GPa, respectively. It is found that the magnesium powders play a more important role than the magnesium particles in the deformation and the densification of the green compact during the pressing, and the pore structure of Ti foam depends on the amount and the size of the magnesium spacer holders after sintering.
The nanoporous structure of oil-impregnated porous copper is closely related to its tribological and oil-retention properties, which are essential for its anti-friction and anti-wear, and long-lasting lubrication. In this study, different component Cu-Al precursors were obtained via plasma-activated sintering, followed by a dealloying method to obtain bulk nanoporous copper with different porosities. The effect of the nanoporous structure on oil-retention capacity and tribological properties was investigated. The results showed that as the porosity increased from 47.48% to 67.69%, the oil content increased from 8.01% to 20.18%, while the oil-retention capacity decreased from 97.12% to 33.92% at 7000 r/min centrifugal speed. With the storage of oil, the average friction coefficient was reduced by 68.2–85.9%. The self-lubricating effect can be ascribed to an oil film formed on the surface, and the main wear forms were abrasive wear and fatigue wear. This study may provide guidance for the development of high-performance oil-impregnated lubricating nanoporous copper.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.