Influence of Water Leaching Process Parameters on Aluminium Foam Manufacturing using Powder Metallurgy Method and Carbamide as a Space Holder

Metal foams are unique materials which have extraordinary property combinations, such as light in weight and high surface area, by introducing pores into them. There are many techniques to manufacture metal foams, and they have various advantages and disadvantages. The end properties of metal foams are highly dependent on pore morphology. To gain control over the generation of desired pore shape, pore size and pore density, the powder metallurgy method using the space holder technique has highly promising results. In this process, samples are made using a mixture of metal powder and space holder, compacted under an enclosed die. These compacted green samples are submerged in liquid media to leach out such space holders. In the present study, foams are made using the powder metallurgy method, where aluminium powder and carbamide space holder were selected as materials. A water leaching process was carried out to remove carbamide. The leaching parameters, such as temperature and submerge time in liquid media, are examined, as they are crucial for obtaining a fully leached space holder and for maintaining the quality of the green sample. The observations reveal that the quality of foam is influenced by factors such as compaction pressure, the quantity of space holder, water leaching time and temperature, or the interaction of all these factors. The spalling is promoted by lower compaction pressure and a higher quantity of space holder, whereas longer submergence times decrease the sample’s green strength. In contrast, higher compaction distorts the shape of pores as well as hinders the removal of the space holder. This study has identified a safe range for producing quality foams with a compaction range of 100 to 150 KN, carbamide weightage of 60 to 70%, and water temperatures between 100 and 120 degrees Celsius. Major Findings: The process parameters were found to have a high sensitivity on the quality of the aluminium foam and the degree of spalling. Careful regulation of these parameters, especially the leaching duration and temperature, can yield noticeable improvements. The findings highlight the significance of controlling processes and parameter ranges to ensure quality consistency. Overall, this work outlines a practical and systematic approach for producing spalling-free foams.