Chrome plating protects components against corrosion and wear, yet hexavalent chromium is permitted for use only in exceptional cases. This is because conventional hard chrome plating uses a great deal of energy, and chrome damages the environment. Fraunhofer and RWTH researchers have therefore developed a cost-efficient alternative to chrome plating: EHLA (extreme high-speed laser material deposition).
EHLA uses a laser beam to melt the powder particles of the coating while they are still above the melt pool, which means that significantly less material needs to be heated (just a few micrometers suffice). The process therefore also makes it possible to coat heat-sensitive components, enables new material combinations, and can also be used for larger components. Moreover, EHLA is also a resource-efficient (90% of the material is used), faster (feed rate of 50-500 m per minute), and more intricate (thin layers of 25-250 μm) process. The coating is non-porous, with no pores or cracks, and firmly bonded to the base material so that it won’t delaminate. Iron, nickel, and cobalt base alloys are used instead of chromium (VI).
Toolmaker Trumpf has already started to integrate EHLA in its laser machines, while Dutch hydraulic cylinder manufacturer IHC Vremac Cylinders has already made the transition from thermal spraying to EHLA.