Electric-Field activated sintering technique (FAST) is a latest development in powder sintering which enables an increase of manufacturing flexibility and high-quality components (e.g. various metals, cermets, magnets and composites with desired structures and functionalities, including use of nano-alloys).
However, existing FAST processes cannot be simply scaled down to the manufacture of miniature/micro-components, due to: difficulties of handling powders; strong “size-effects” at the micro-scale; different sintering mechanisms at the micro/nano-scale; lack of design, manufacturing guidance and facilities for producing complex shaped components through high-throughput and cost-efficient production. In fact, almost all the current applications of FAST involved component larger than 5.0 mm, reflecting these constraints.
A new process concept - Micro-FAST - is proposed which scales down conventional FAST process to the micro-scale (<5.0 mm) and combines micro-forming with FAST sintering resulting in a high efficiency process.
Near-net-shaped, bulk fully-dense (up to 100%), nanostructured components will be produced with expected significant increase of mechanical and functional properties.
The main techniques to be used for overcoming barriers of the FAST process at micro scale are:
- Combining micro-forming with the FAST to enable complex shapes/features at the micro-scale, assisted by using large current density;
- Using multi-scale modelling techniques to develop understanding of the mechanism of the powder densification at the micro-/nano-scale;
- Directly forming the component using the shaping dies/moulds without using lubricants, including a laser die-cleaning technique integrated into the forming-machine;
- Introducing in-situ handling to enable handling of the micro-components inside the machine-chamber
- Developing innovative nano-phased powder materials (with particular interest on difficult-to-cut and difficult-to-form materials eg, metallic alloys, ceramic, nanocomposite).