The potential for applying metal foams in lightweight construction is mainly based on the increased stiffness of two flat or curved sheets separated by a foam layer. Attempts have been made in the automotive industry to reduce weight by traditional measures; however, decreasing wall thickness may increase potential for buckling of the structure. In this regard, cellular metals can be effectively employed. Most methods to produce lightweight porous materials utilize foaming methods, i.e., via incorporating additives, which cause gas evolution within the solid or liquid material. Other approaches rely on incorporating oxides to stabilize cell walls. However, introduction of foreign materials to metallic systems can cause detrimental effects and poor mechanical properties in certain reactive metals.
Researchers at the University of Michigan have developed a method for producing microporous objects having a fiber, wire or foil core. Microporous objects are created by deposition of small dimension of solid from liquid streams undergoing solidification with the simultaneous welding of the streams at various nodal locations concurrently during the deposition process. The process is easy to vary so that the product can range from sheets to finished shaped parts, and the pore density may be varied over a wide range. Since the internal structure of the product is microporous or made of interconnected fibers, the product can be lighter yet stronger and stiffer than solid parts or sheets.
Applications and Advantages
- Aerospace structures and engine parts
- Automotive crash energy absorbers, seat backs, sound dampeners, and strain isolation layers
- Lightweight but strong and stiff product
- Does not utilize contaminants
- Allows the creation of unit pore size