Press Forming of Aluminum Foam during Foaming of Precursor

Abstract

Al foam was press-formed utilizing a steel mesh die during the foaming of the precursor to shape the Al foam. The effects of the temperature of the precursor and the pressing velocity during press forming on the forming behavior of the obtained Al foam were investigated. It was found that Al foam was sufficiently softened above the liquidus temperature to conduct press forming. In contrast, press forming cannot be conducted below the liquidus temperature. The press forming of Al foam should be conducted after the Al foam has been sufficiently foamed above the liquidus temperature to obtain high-porosity Al foam. No extrusion of Al foam through the mesh openings occurred even when press forming was conducted above the liquidus temperature. The Al foam and steel mesh were easily separated. The mesh pattern was clearly observed on the surface of Al foams. There is little effect of conducting press forming on the pore structures of the obtained Al foams regardless of pressing velocity. Al foam with a triangular cross section having the same shape as the steel mesh die and a porosity of approximately 80% was obtained. The press-formed Al foam sufficiently filled the steel mesh die. Consequently, it was demonstrated that the press forming of Al foam after sufficient foaming is effective for fabricating Al foams with complex shapes.

X-ray Radiography Inspection of Pores of Thin Aluminum Foam during Press Forming Immediately after Foaming

“…Generally, pores collapse during the formation of aluminum foam [13][14][15], similarly to the one observed [16][17][18]. In contrast, the surface of the die can be transferred to the aluminum foam while retaining the pores by press forming immediately after foaming [10]. In our previous study [11], X-ray transmission was attempted as a means of observing pores during press forming to confirm their retention without collapsing during press forming.…”

“…Recently, the press forming of aluminum foam immediately after foaming but before solidification has been proposed [10][11][12]. In this forming process, the precursor can be directly heated because of the absence of the mold, and the cooling rate is high owing to the use of a cold die as the press-forming die.…”

Friction Welding of Polycarbonate Plate and Aluminum Foam Fabricated by Precursor Foaming Process

“…To obtain a shape suitable for friction welding, the aluminum foam was pressed immediately after foaming to prepare a flat aluminum foam (10 mm in thickness). The foamed aluminum can be formed into a flat shape without fracturing pores by pressing immediately after foaming before the temperature of the foamed aluminum drops below the liquidus temperature [47][48][49]. The surface of the pressed aluminum foam was milled to remove 1.2 mm-1.6 mm to expose the pores because the pressed aluminum foam had a dense skin layer on the surface.…”

Fabrication of Two-Layered Aluminum Foam with Closed-Cell and Open-Cell Structures and Shaping of Closed-Cell Layer by Press Forming Immediately after Foaming

“…Recently, the technique of press forming of softened aluminum foam during or immediately after the foaming of the precursor was developed [17,18]. In the press forming process, first, the precursor was heat-treated using halogen lamps.…”