Acid-assisted consolidation of powder compacts: cold-welding or cold sintering

Silver powder that has been treated in dilute fluoroboric acid solution and compacted at room temperature displays surprisingly elevated flexural and even tensile strength. The density and mechanical strength values increase with increasing compaction pressure. The flexural strength and the elastic moduli of silver powder compacted at 1 GPa, as determined by sound velocity measurements, reach values comparable to those of bulk silver. The results can be tentatively interpreted either in terms of an ambient temperature s elf-soldering effect of silver in the presence of the fluoroboric acid, act ing as a fluxing agent, or as cold liquid-phase sintering in an aqueous liq uid medium. (C) 1999 Kluwer Academic Publishers.