SELF PROPAGATING SINTERING OF NANOSIZE POWDERS

摘要

Powders approximately 100 nanometers in diameter, which are made by the process of electro-explosion of wire in argon, have stored surface and strain energy that is released at threshold temperatures well below the melting point. This allows sintering to occur at relatively low temperatures with self heating. We studied the sintering of copper and aluminum powders made by this process, by heating cold-pressed pellets to approximately 400 C, at which point they would exotherm with the generation of light and sufficient energy to partially melt the pellets. This self heating phenomena was observed with many other 'electroexploded' powders including nickel, silver and titanium, although the self heating phenomena is more predominant with the more noble metals silver and copper. These self-heating powders are suggested as sintering aids when added to normal powders, and in situations where reduction of sintering time is critical.