The aim of the conducted investigations was to characterize the corrosion and wear properties of graded Zirconiumcarbide and Chromiumcarbide PVD layers on low-alloy steel with tribological and electrochemical test methods. Thus the mechanism of deterioration should be clarified and the coatings should be further developed to adapt them to the conditions in regions of pumps, which are fluid contacted. Finally the optimized PVD coatings should be investigated comparatively under erosion-corrosion conditions, which are close to application. Therefore a new test rig had to be developed, designed and applied. As a result of these investigations an assessment of the applicability of such coatings on low-alloy steel in pumps was aspired. In fact one conclusion of the conducted studies is, that an application of the investigated PVD coatings on low-alloy steel under pump conditions seems to be possible, depending on the operational conditions. The conducted coating developement started with PVD layers with about 3 µm thickness, which yielded several corrosion sites and high current densities in polarisation tests. As a result of the coating developement 10 µm thick multilayer coatings were available, which were free of corrosion sites after polarisation tests and yielded very low current densities. But for an industrial application of PVD coated low-alloy steel the corrosivity of the media and the duration of the contact with these media have to be considered, due to the time dependent nature of corrosion processes. Hence for a long term operation of these PVD layers in applications such as pumps a further coating developement may be required. Furthermore the friction and wear properties of the developed PVD coatings were investigated. As a result wear and friction for unlubricated sliding, e.g. as it appears in a pump, which runs dry because of a failure, were significantly reduced with respect to uncoated low-alloy steel. Even with lubrication by a typical aqueous pump medium the amount of wear was considerably decreased. In summary can be stated, that a good wear protection and reduced friction were achieved by the developed PVD coatings. Last but not least PVD coated low-alloy steel was investigated comparatively under erosion-corrosion conditions, which are close to the mentioned application in pumps. One result of these studies was, that the developed test rig successfully simulates erosion-corrosion as it occurs in pumps. For the optimized 10 µm thick multilayer Chromiumcarbide coating, which performed very good in polarisation tests, impingement wear, caused by coating flaws, combined with corrosion was detected. Hence an application under similar conditions with hard particles impacting on the surface, which is a relative hard load for comparatively brittle layers, is at this time not advisable. But there is a good chance to improve the erosion-corrosion behaviour by avoiding these coating flaws in futher coating developement. For the future, further studies with a more flat impact angle of the particles may reveal a better suitability of the very hard PVD coatings, which showed no traces of abrasive wear in the tests.