Metal foams have recently attracted considerable
attention in both academia and industry because of their
exceptional mechanical, thermal, acoustic, electrical and
chemical properties [1–4]. For structural applications,
such as energy absorption, the most important considerations
are porosity, specific strength, ductility in compression
and cost. The overwhelming majority of metal
foams in the market are therefore closed-cell Al foams
manufactured by liquid or semi-liquid foaming technologies.
For functional applications, such as sound absorption,
thermal insulation, heat dissipation and catalyst
support, the cells need to be open and small. The metal
matrix may be Cu-, Fe-, Ti- or Ni-based. These metals
have much higher melting points than Al. Solid route
manufacturing technologies are then often adopted.
Sintering a compact of metal powder incorporating
removable salt particles is a cost-effective route for producing
metal foams with controlled cell shape, cell size
and porosity. Zhao and his colleagues [5–8] developed
the SDP process for manufacturing Al foams. SDP uses
NaCl powder as the filler material. The main limitation