Sustainable Production of Powder Metallurgy Aluminum Foams Sintered by Concentrated Solar Energy

Abstract

Porous aluminum foams were successfully fabricated following the space-holder powder metallurgy method with a solar sintering stage. Al foams with porosities of 50, 60, and 70 vol.% were sintered in a low-cost Fresnel lens. Green parts were prepared using aluminum powder as the main metallic material and saccharose as a soluble space-holder. The dissolution stage was designed for each foam and required longer periods of time, between 8 and 32 h, as the design porosity increased. Brown parts were fully sintered by concentrated solar energy at a lower temperature (500 °C) and for shorter times (12–20 min) than those required by conventional sintering techniques (640 °C, ~9 h). The evaluation of density and the characterization of pore size and distribution in the sintered foams was carried out. All obtained foams were stable and presented a homogeneously distributed porosity, very close to the design porosity, with differences lower than 2.1 vol.%, and with approximately half being characterized as open porosity. Moreover, the solar sintered foams presented a high quality, and similar or even greater mechanical properties (such as compressive strength and impact energy absorption) than those achieved by conventional techniques. Foams with 50 vol.% of porosity exhibited the best mechanical behavior, in terms of impact-energy absorption (24.42 MJ/m3) and compressive strength (27.4 MPa).

Use of Molding Mixtures for the Production of Cast Porous Metals

“…The foundry way of producing this material presents a number of advantages; it is a time-and energy-saving process with the possibility of producing shaped porous parts from a wide range of materials (ferrous and nonferrous alloys). In these respects, even advanced metallic foam technologies such as 3D printing or powder sintering [14,15] cannot compete with foundry processes.…”

Rice Husk Ash as Pore Former and Reinforcement on the Porosity, Microstructure, and Tensile Strength of Aluminum MMC Fabricated via the Powder Metallurgy Method

“…According to Kheradmand et al, powder metallurgy has various benefits, including a high fabrication rate, homogeneous microstructure fabrication, a reduced number of secondary steps, and a working range for the fabrication of large alloy composites which makes it extremely applicable to the fabrication of porous aluminum [9]. Cañadilla et al [10] successfully produced porous aluminum with a tensile strength of 281.6 MPa and porosity of 60.8% using saccharose solution as a pore-forming agent at a volume percentage of 70 vol.%. As for Kumar and Golla [11], sodium chloride was utilized in the production of porous aluminum with a tensile strength of 1590 MPa and a porosity of 34.16%.…”

Archives of Metallurgy and Materials

“…additive manufacturing, powder sintering, etc. [18,19]) for the production of the material under study, the attention of experts has been directed in recent years towards finding other, less complicated processes.…”