Microwave-assisted fabrication of titanium hollow spheres with tailored shell structures for various potential applications

Expanded polystyrene spheres are spray-coated with a Ti–7Ni-0.5B-binder slurry. The polystyrene core and binder are thermally removed and the resulting Ti-7Ni-0.5B shells are sintered by microwave radiation to produce titanium hollow spheres. Samples sintered at ≤1120 °C result in individual hollow spheres with permeable shells, while sintering at higher temperatures lead to an interconnected hollow-sphere structure with solid shells.

► Titanium hollow spheres with different shell structures are fabricated from titanium powder.
► Microwave sintering allows fast fabrication of titanium hollow spheres due to skin depth effect.
► Sintering temperature is critical in determining the shell structure.