Metallic Foams

Brief Info Metal foams – most are made from aluminium, although steel can also be used. There are many benefits of metal foams, including a very good strength-to-weight ratio. Metal foams are cellular structures made with metal rather than polymers. They are often used as soundproofing in vehicles, or as crash protection. In electronics they can be used as heat sinks.

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How metal foams are made Production Method Metallic melts can be foamed by creating gas bubbles in the liquid. These gas bubbles in the metallic melt tend to rise to the surface due to the high buoyancy forces in the high-density liquid. In order to prevent this from happening, the viscosity of the molten metal has to be increased. This can be done by adding fine ceramic powders or alloying elements to form stabilizing particles in the melt. Three ways of foaming metallic melts are listed below: Injecting gas into the liquid metal from an external source Causing the precipitation of gas that had just been dissolved in the liquid Causing an in-situ gas formation in the liquid by admixing gas-releasing blowing agents to the melt

The properties of metal foams Metals that Can Be Used The metal that is commonly used to make metal foams is aluminium. However, other varieties of metals can be used to make the foam, such as titanium and tantalum. Properties of Metal Foam The key properties of metal foam are as follows: • Ultralight material (75–95% of the volume consists of void spaces) • Very high porosity • High compression strengths combined with good energy absorption characteristics • Thermal conductivity is low • High strength

The engineering applications of metal foams The main applications of metal foams and porous metals are listed below: • The closed variety is used for structural applications requiring load-bearing features, and for weight-saving and impact-absorbing structures in vehicles • The open variety is ideal for vibration and sound absorption, filtration and catalysis at high temperatures, for heat exchange and in medical devices. • The open variety is also useful in functional applications such as filtration and damping. • Foam metal is being used as an experimental prosthetic in animals. • Metal foams with high strengths can act as high-capacity impact-energy absorbers. • Automotive industry - the foams reduce the number of parts in the car frame, facilitate assembly, thereby reducing costs and improving performance.

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The advantages of metal foams compared to other materials Currently, body Armor plate inserts are made of ceramic composites. However, they are bulky, heavy, and vulnerable to accidental fracture. A plate insert made of the new composite metal foam, on the other hand, could be significantly thinner and lighter.