Powder-metallurgical process for producing metallic microchannel devices

Abstract

We investigated a simple and economical method for producing free-form microchannels in metal bodies. The concept for our process is based on a microscopic infiltration phenomenon that often occurs during liquid phase sintering of a mixture of metal powders with different melting points. A shaped compound of the metal powder with lower melting point and an organic binder are used as the sacrificial core that gives the shape of the microchannel. A body-metal powder compact that includes the sacrificial core is sintered at a temperature between the melting points of the sacrificial-core metal and body metal. The organic binder is removed during heating of the powder compact, and infiltration of molten sacrificial-core metal into the body-metal powder produces a microchannel and a lining layer. We examined following combinations of metal powders: titanium-aluminum, nickel-aluminum, copper-tin, and iron-copper. Metallographic observations confirmed that microchannels were produced in the metallic bodies in all these systems. Furthermore, in the case of the titanium body metal with an Al-Cu alloy sacrificial-core metal, the inner wall of the microchannel was smoother than the case of titanium with aluminum. The copper content of the sacrificial-core metal influenced the composition and structure of the microchannel lining. © 2006 The Japan Institute of Metals.