Combining Sliding Wear and Corrosion Resistance for Coating Materials on Hydraulic Cylinders

Laser cladding and thermal spraying are nowadays becoming recognized as surfacing processes for coating of hydraulic cylinders, substituting the electrolytic hardchrome process. In contrast to hardchrome, where the coating material is always chrome, in laser cladding and thermal spraying a wide variety of materials are available. This poses the possibility to adapt the coating material to the service environment. While this is a large chance, it also makes the selection of the right material, that is a durable but economic solution, harder. In this study cost-effective Fe-based materials were tested against a highly wear and corrosion resistant Co-based Stellite® 21. The coatings were investigated regarding their resistance against sliding wear in a pin-on-disk test and against corrosion in a potentiodynamic corrosion test in a sodium chloride solution. As references the established coatings HVOF WCCoCr and two hardchrome coatings of different qualities were used. Fe-based materials could combine moderate wear and corrosion resistance while being an economic choice of coating material.