Foam Materials (Foam Metals)

A new class of cellular structure materials having extremely low density in combination with high strength-to-weight ratio, surface, noise absorption, low hydraulic resistance.

There are several methods of production: casting, suspension (slip process), chemical, galvanic, gas-cycle, and their combinations. The cell is a basic structural element of this material.It has a form of an oblong pentagonal ellipsoid of revolution.

The internal structure, strength and hydraulic characteristics are basically defined by structure parameters of a parent matrix, porosity and relative density. Depending on a production method, class of material, peculiarities of technological modes there are differences in the matrix microstructure and bridges. Channel porosity remains in the place of the removed matrix (except foam metals produced with casting method). Volume of a trihedral channel pores makes 2–3% from the total material volume, and they make up a three-dimensional connected network penetrating the entire sample.

Main characteristics and properties of foam materials:

• Open cellular net structure;
• high rate of open interconnected porosity 80–97%;
• channel porosity;
• high ratio of elasticity and durability modules to density;
• vibration stability;
• high cohesiveness of elements;
• uniform energy absorption at deformation;
• high gas permeability;
• small hydraulic resistance;
• absence of optically through channels;
• intensive mass — and heat — exchange with environment flowing through the material;
• several heat transfer mechanisms in the material structure.

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Substances for foam metals

Foam materials can be produced from quite different basic materials: nickel, copper, iron, nichrome, aluminium, fechral, chromal, stainless steels and alloys, bronze, monel, cobalt, rhodium, platinum, gold, silver, carbon, ceramic compounds (oxides, carbides, nitrides, borides, silicides). The given class of materials is used the various fields. At the same time they are still little-known by the majority of possible consumers.