Vibration induced cavitation loading can lead to damages on pump components, valves, and
cylinder liners. Both the efficiency and the life time of affected components are reduced by the
extensive mechanical and corrosive loads. Cavitation tests, like the vibratory apparatus (ASTM
G32-16), are important material-scientific techniques. By verifying cavitation resistant materials
or understanding basic wear mechanisms and failure modes by means of cavitation tests, costs
for maintenance, reparation or replacement of affected components can be reduced.
Cavitation has always a geometrical impact on the component surface. Depending on the
material, cavitation loading causes deformation, pitting, cracking or fatigue wear. Coatings
could delaminate or flake-off. These surface alterations in turn influence the formation of
cavitation bubbles in terms of size, speed and impact pressure so that the cavitation intensity
and the cavitation erosion is significantly affected. To ensure a testing which fits service-like
demands, an estimation of the cavitation intensity, for example in terms of correlation factors,
would be a major advance and is therefore a primary aim of the current investigations.
The investigations focus on the impact of cavitation on the bulk materials EN-GJL-250 (gray
cast iron with lamellar graphite) and EN-AW-2024 (age-hardened aluminium-copper-alloy).
EN-GJL-250 is a widely used pump material because of low costs and easy machinability. The
EN-AW-2024 alloy is a soft light weight construction material, which is often used in aerospace
and aircraft constructions. As a coating material a highly corrosion resistant and ductile
electroplated nickel coating is investigated. Due to the different properties of these materials
different wear mechanisms and failure modes for cavitation induced fatigue stress can be
observed. To determine the influence of several parameters on cavitation, the materials are
tested with a vibratory apparatus (ultrasonic oscillator), using the direct and indirect set-up.
Beside the variation of vibration amplitude and distance between vibrating surface and
specimen, the influence of the gas-content of the used medium on the bubble formation is
investigated. In addition material dependent measurement intervals and test durations are
specified. These measurements are intended to characterise and quantify the fatigue behaviour
of EN-GJL-250, EN-AW-2024 and the nickel coating. The surface characterization is performed
with tactile roughness measurement, metallography, 3D-microscopy and scanning electron