Effectivity of Hard Chrome Coatings in Cold Rolling Processes

The thesis concerns hard chromium coatings on work rolls in cold rolling, used for their positive effect on strip cleanliness. Even after decades in industry, how these coatings work is not well enough understood, while REACH-driven environmental and regulatory pressure over hexavalent chromium has made alternatives urgent. The work therefore studies links between surface properties, lubrication and strip cleanliness, combining laboratory studies with pilot-scale cold rolling trials.

It seeks to separate the roles of surface cracks, roughness and wettability in the coatings' tribological behaviour. Surface and interface characterization used confocal microscopy, SEM/EDX, AFM and XPS. Wettability was examined by contact-angle measurements, and lubricant spreading by fluorescence-based plate-out experiments. These assessed surface topography, wetting behaviour and lubricant distribution.