Fabrication and porosity evaluation of porous copper by centrifugal casting

초록

Porous materials have recently been used as functional materials owing to their distinguished properties such as large specific area, high relative strength and high fluid permeability. Lotus-type porous metals, which possess long cylindrical pores, have been attracted much attention because of their unique pore morphology compared to those of conventional porous and foamed metals with spherical pores. Conventional fabrication methods for these metals have been known as mold casting, continuous zone melting technique and continuous casting. These fabrication methods have one significant drawback. That is the lack of economic feasibility and safety for the use of the metals at the industrial fields because high pressurized hydrogen gas is required as a pore former. In this study, a new method was developed to improve the economic feasibility and safety for the fabrication of lotus-type porous metals. In this method, centrifugal force was introduced to replace high-pressure hydrogen gas in the conventional methods. Lotus-type porous copper was fabricated by centrifugal casting at a various rotational velocity under a hydrogen gas pressure of 0.1 MPa. The results showed that porosity and average pore diameter were decreased with increasing the rotational velocity and radius. Furthermore, an equation for the calculation of porosity subject to the rotational velocity and radius was derived in this study. As a result, calculated value and experimental value were in good agreement with the equation.