Recyclate from plastics has to have defined technical properties to enable products with certain performance characteristics to be manufactured in downstream processing. For plastics product with a lower quality requirement, waste without a precisely defined composition is also recycled today.
One process in the production of plastic recyclate is the mechanical comminution of the waste. The components, e.g. impact bars, used in the comminution units of recycling plants have to meet high requirements with regard to their mechanical and tribological strength.
Suitable for this application, depending on the specific requirements, is the use of materials on oxide and non-oxide ceramic basis, such as Al2O3, ZrO2, SiC, Si3N4, mixed ceramics as well as carbides.
Typical properties of ceramic components for size reduction equipment are for example:
- Density: >98 % of the theoretical value
- Microstructure optimized for tribological applications
- High compressive strength
- High impact strength
- High wear resistance
- No abrasion that would impair the quality of the comminuted product
- Topography optimized for tribological applications
- High edge stability
- High thermal strength
- High thermal shock resistance
- No contact reactions with the comminuted material
- Realization of ceramic-metal composites by means of force, form-fit, and substance-to-substance joining techniques, the latter, for instance, by means of brazing with silver-based brazing metals
Depending on the specific comminution duty, oxide and non-oxide ceramic components are often state of the art today as they can make a key contribution to the cost-efficient operation of such plants thanks to their above-listed properties.