Hollow spherical structure
Hollow spherical structures are a subgroup of cellular materials. The structures consist of spherical cells with a narrow diameter distribution. A distinction is made between metallic and ceramic hollow spherical structures.
One possible manufacturing variant is the sintering of foam polystyrene balls coated with metal powder or ceramic powder . In general, almost all common sinterable materials can be used as sintering powder.
Metallic hollow spherical structures
Metallic hollow spherical structures can be described as a metal foam which is characterized by a combination of open and closed porosity and spherical cells with precisely adjustable cell diameters and cell wall thicknesses.
Materials and properties
Depending on the ball diameter and the thickness of the spherical shell, metallic hollow spherical structures with different densities can be created. Typical values are between 0.3 and 1.5 g / cm³. By designing the manufacturing process accordingly, the walls of the spherical cells can be made tight or open and porous.
Common materials for metallic hollow spherical structures are:
- Low alloy steel
- Stainless steels (e.g. 1.4404, 1.4841, 1.4767)
- Nickel and nickel alloys
- Intermetallic compound
- molybdenum
- tungsten
- Precious metals
Areas of application
The manufacturing process has now been developed to such an extent that the structures can be manufactured on a pilot plant scale and the start of industrial production is imminent.
Possible areas of application are, for example:
- Acoustics (sound absorption in vehicle and mechanical engineering)
- Heat protection
- Absorption of mechanical energy (crash absorber)
- Turbine construction (abrasive seals)
- Lightweight structures (realization of light, rigid structures)
They are in competition with similar material groups such as metal foams or ceramic foams .