Jörg Ellermeier

The effect of layer structure on corrosion and erosion resistance of thin PVD multilayer films

Abstract This paper contributes to the development of physical vapour deposition multilayer coatings to resist erosion in corrosive environments. The influence of the deposition parameters of the bonding layer on adhesion has been investigated. Furthermore, the influence of the layer design on the corrosion resistance and the thickness of the diamond-like carbon top layer on the erosion resistance of the investigated multilayer coating have been studied. Corrosion and erosion tests as well as scratch tests, metallographic and scanning electron microscope investigations were carried out to characterize the coatings and their degradation behaviour.

Influence of the layer architecture of DLC coatings on their wear and corrosion resistance

Abstract In this work, the influence of diamond-like carbon top layers deposited on two different types of layer architecture on wear and corrosion resistance is investigated. Physical vapour deposition coatings with a-C:H top layer of various thicknesses were deposited on plasma nitrided 42CrMo4 by reactive magnetron sputter ion plating. Beneath the top layer, an architecture with and without a-C interlayers was deposited. Investigations using potentiodynamic polarisaton testing in artificial seawater as well as an impact tribometer show that it is possible to protect low-alloy heat treatable steel from both corrosion and wear by using pre-treatment and an appropriate diamond-like carbon coating. Thicker a-C:H top layers as well as the addition of a-C interlayers resulted in an overall improvement in the coating behaviour.

Zum Verhalten rost- und säurebeständiger Stähle unter Komplexbeanspruchung. Teil 1 Passivität und Lochkorrosionsbeständigkeit

Iron-Chromium-Nickel alloys are of special interest for many applications because of their excellent resistance to corrosion. The nature and composition, of passive films formed on stainless steels depend on the prevailing conditions, viz. steel-composition, passivation potential, aging, pH, electrolyt composition and temperature. Passive films may be damaged by local breakdown. At least two mechanisms are possible for this localisation: mechanical breakdown by slip steps and electrochemical breakdown (for e.g. by the effects of chloride ions). Because of this, steels suffer a degradation of their fatique properties when exposed to an aqueous environment. Passivation of austenitic, ferritic-austenitic and martensitic stainless steels has been studied in different solutions using electrochemical techniques. The results clarified that for two of the investigated alloys the prediction of fracture initiation based on pitting corrosion in chlorid containing solutions is possible.