Industry leaders are abuzz with what the future holds thanks to an innovative 3D-printing technology called additive manufacturing (AM). “The increasing intrigue surrounding AM technologies stems from their multifaceted potential to revolutionise industries,” commented Mojtaba Salehi, a Scientist from A*STAR’s Singapore Institute of Manufacturing Technology (SIMTech).
In binder jet AM, a liquid binding agent is selectively deposited to join powder particles together, layer by layer, to form a solid object. Salehi explained that this technique offers unmatched design flexibility; faster, greener and more cost-effective alloy fabrication processes; as well as the prospect of novel materials.
Salehi and team have been investigating the challenges of deploying AM for magnesium alloys, light and biodegradable metals used in aerospace and biomedical engineering. “Each magnesium powder particle used in AM is inherently covered with a magnesium oxide film,” said Salehi, adding that this naturally forming layer acts as a barrier that prevents powder particles from effectively sticking together, thereby weakening the end product.
In their study, the researchers discovered a nano-sized solution to these big engineering obstacles. They found that adding calcium nanoparticles during the AM process helps to break down the oxide layer on the magnesium powder, allowing particles to fuse strongly and enhancing the sintering process.
Micrographs of binder jet-printed and sintered samples of (a, c) a magnesium (Mg) powder feedstock, and (b, d) a blend of Mg and calcium (Ca) nanoparticles. Images were captured via scanning electron micrography (SEM) and analysed with Electron Backscatter Diffraction (EBSD). Each EBSD colour represents individual Mg grains while black areas represent pores. Circular grains originated from the primary Mg powder, while the irregular grains resulted from Mg particles coalescing together during the sintering process.
Samples printed with the addition of calcium nanoparticles were then subjected to a battery of tests including microscopy, chemical analyses and mechanical testing through collaborations with the lab of Daniel John Blackwood at the National University of Singapore. The team found that calcium-containing nanoparticles boosted densification rates by 25 percent, which translated to impressive gains in strength and flexibility for the magnesium samples produced.
Calcium nanoparticles were found to improve the densification rate by 25 percent which translated to impressive improvements in the strength and flexibility of the resultant magnesium samples. “The resulting physical and mechanical properties can potentially match or exceed those of cast magnesium components,” said Salehi, adding that over 95 percent of magnesium components are currently made using traditional casting techniques.
These results highlight how a targeted nano-alloying approach can catalyse innovation across diverse industries. Salehi and colleagues are currently working on developing denser, stronger and easy-to-manufacture magnesium alloys using AM to support the trend towards customised, on-demand manufacturing in various sectors.
The A*STAR-affiliated researchers contributing to this research are from the Singapore Institute of Manufacturing Technology (SIMTech).
