Piezomechanik GmbH

Multilayer stacks need a careful electrical insulation of the surface of the active PZT-ceramics to separate the internal layer electrodes electrically. Currently an “opinion” is promoted as “leading edge” technology, that a passive ceramic layer coating is the answer to everything especially in contrast to polymer coated elements.

Practice shows, that this philosophy works with only gradual advantage for limited static applications on the condition, that the strain levels are held below 0.1%.
Regarding the full spectrum of piezo application profiles it has turned out, that polymer coated elements have dramatic advantages under general application aspects!
A special highly mineral filled expoxy (MFE) coating provides a remarkable on all around mechanical preloading of the actuator ceramic. This preload pressure is the consequence of the elastic polymer shrinking during the cure process.

The mechanical stability and strength of the stack against bending forces is dramatically enhanced thereby compared to purely ceramic standard isi-structures with their stress relief notches in the stack surface structure.
Resonant bending modes are highly damped by the polymer.
The utmost stability is therefore given for the osi-type piezo elements PSt 150 with the highly stable ceramic structure in superposition with the further enhancement of mechanical stability by the standard MFE coating.

This works excellently even for bending sensitive large aspect ratio’s of the osi-based PSt 150 actuators (length/cross section).
In industrial use, PIEZOMECHANIK’s osi-based large stroke elements ( > 100 µm) are permanently cycled with high strain rates
> 0.1 % and high dynamics since years without failure.
In total, cycle numbers have been proofed exceeding 10¹¹ under the above conditions.