In a significant stride towards sustainable maritime materials, researchers have developed a cost-effective method to produce high-performance porous aluminum alloys using recycled A356 aluminum chips. The study, led by Jinwoo Baek from the Interdisciplinary Major of Maritime AI Convergence at the National Korea Maritime and Ocean University in Busan, South Korea, was recently published in the journal ‘Metals’ (translated from Korean).
The research tackles two critical issues in the maritime industry: the high cost and limited applicability of conventional foaming agents like TiH₂, and the underutilization of recycled aluminum materials. By incorporating a low-cost alternative foaming agent, Na₂B₄O₇·10H₂O (commonly known as borax), either individually or in combination with TiH₂, the team successfully fabricated porous aluminum alloys with enhanced properties.
Baek and his team investigated the effects of varying the content of foaming agents (1, 1.5, and 3 wt.%) on pore characteristics, microstructure, hardness, and corrosion resistance. They found that TiH₂ increased porosity and promoted grain refinement, improving both hardness and corrosion resistance. Meanwhile, borax exhibited effective pore formation and hardness improvement at lower concentrations (1–1.5 wt.%), but its corrosion resistance deteriorated as its content increased.
The sweet spot, however, was found in the combined addition of both agents at 1.5 wt.%. This combination showed excellent pore formation and corrosion resistance properties, with a relatively high pore area fraction (2.38%), porosity (27.0%), and impressive hardness (59.35 ± 6.4 HV). As Baek puts it, “This study demonstrated that Na₂B₄O₇·10H₂O (borax) foaming agent can be an economic alternative to TiH₂, and shows that the performance of porous aluminum alloys can be effectively improved by optimizing the combination of recycled raw materials and foaming agents.”
For the maritime industry, these findings present a promising opportunity to reduce manufacturing costs and enhance the sustainability of lightweight structural materials. Porous aluminum alloys are widely used in marine structures, energy absorbers, and buoyant components. By utilizing recycled materials and a cost-effective foaming agent, shipbuilders and offshore operators can potentially lower their environmental impact and operational expenses.
Moreover, the improved hardness and corrosion resistance of these alloys can extend the lifespan of maritime structures, reducing maintenance costs and downtime. As the industry continues to seek innovative solutions to balance performance, cost, and sustainability, this research offers a compelling case for the adoption of recycled materials and alternative foaming agents in the production of porous aluminum alloys.
In the words of Baek, “This study opens up new avenues for the development of sustainable and cost-effective materials for the maritime industry.” With the findings published in ‘Metals’, the stage is set for further exploration and application of these advanced materials in real-world maritime scenarios.