The economical operation of a production plant for paper is influenced to a major extent by the following variables:
- Demand for electrical energy and water
- Lifetime of components exposed to wear
- Downtime for repair and maintenance
One position in such a plant that is exposed to severe wear is the dewatering area as there a rotating screen separates the water from the solids. This screen moves over so-called suction boxes, the screening side of which is fitted with panels made of wear-resistant materials. Depending on the production rate, today various types of material are used, e.g. plastics, filled plastics or oxide and non-oxide ceramics. Pure ceramic materials achieve maximized wear resistance in use and therefore significantly contribute to the economic operation of a plant even at high production rates.
For use as suction box covers, suitable oxide and non-oxide ceramics made of Al2O3, Al2O3-ZrO2 mixed ceramics (ZTA), ZrO2, SiC and Si3N4 have the following material-independent typical properties:
- High degree of purity
- Low surface porosity
- High mechanical strength and toughness
- High edge stability
- High dimensional accuracy
- Suitability for production rates of 1 000 m/min and even much higher
- High wear resistance
- Behaviour making them gentle on the screens used
- Thermal shock resistance to a ΔT level of around 600 K today
Suction box covers made of high-quality ceramic prove their high quality especially through their reliability in long-term operation exposed to mechanical and thermal loads and also in technically problematic operating situations.
On account of the above-mentioned properties, the use of oxide and non-oxide ceramics is also recommended for such components used in other positions in a plant where demanding technical requirements have to be met. They generally achieve a reliably long service lifetime in such operating conditions.