Fabrication of Lotus-Type Porous Copper Using Slip Casting and Sintering Techniques for Heat Pipe Applications

A lotus type-porous copper will be used to substitute wick materials from tabulate coral capillary for heat pipe applications. The lotus type-porous material are normally fabricated using Gasar process, in which unidirectional solidification was applied to the metal-eutectic systems to obtain long cylindrical pores in the direction of solidification. A new process is proposed to fabricate the lotus type-porous material using slip casting and sintering. As an initial work, this paper is aimed to obtain appropriate processing parameters of fabrication of lotus-type porous copper using slip casting and sintering techniques. Nylon strings were used as pore formers to form cylindrical pores. They were coated with copper slurry consisting of copper powder and binding agent. The coated nylon strings were arranged in a mold and the slurry were poured. After drying, these castings were sintered at various sintering temperatures and sintering times. The results showed that starch as the binding agent is superior to PVA. The mixture of starch-water with starch content of 97%, the copper slurry with copper content of 50% by volume, the copper powder size of 200 µm, the sintering temperatur of 900°C, and the sintering time of 60 minutes are able to produce lotus-type porous copper similar to that produced through Gasar process.

Metallograpiuc Study of Gasar Porous Magnesium

ABSTRACTOne of the promising techniques for making porous metals is the so-called GASAR process. In principle, the process affords considerable control over pore size, shape, and distribution. However, in practice, the pore microstructure is difficult to control, and a clearer understanding of microstructural evolution would be helpful. In this study, we undertake a detailed microstructural study of a porous Mg and AZ31 Mg alloy synthesized by the GASAR process. Microscopic studies demonstrated the presence of different pore size ranges. The pore distribution depended on the distance from the chill end of ingots. TEM observations revealed apparent crack lines (gas tracks) near the pores and ternary intermetallic phases in the alloy.