Hardide Coatings, innovator in advanced surface coating technology, has developed a revolutionary alternative to toxic hard-chrome plating (HCP) which will soon be restricted or banned.
Hardide-A meets strict new EU and US environmental standards and provides comparable wear, corrosion, hardness, surface finish and substrate bonding properties to HCP. Unlike most HCP alternatives, Hardide-A is also suitable for internal surfaces and complex shapes.
HCP has been a mainstay of industrial coating in aerospace, heavy equipment, automotive and various other industries for many years. However, the hexavalent chrome salts used to produce HCP pose extreme health and environmental hazards.
The safeguarding EU and US regulations mean chrome plating is incurring rising costs, extensive regulation and onerous paperwork. Under EU REACH, HCP use will be severely restricted and could be banned. A search has been led by the aerospace industry to find suitable alternatives.
Hardide-A matches the standard thickness (50-100 microns) and hardness (800-1200 Hv) of HCP, simplifying the transition without need for dimensional changes or drawing re-design. HCP’s intrinsic performance limitations hinder its more demanding wear applications and Hardide-A outperforms it in several key areas. This includes enhanced protection against corrosion, wear and chemically aggressive media, enhanced fatigue life and a non-porous structure.
A number of other alternatives to HCP are available including thermal spray, in particular high-velocity oxy-fuel (HVOF) and emerging processes such as electroless nickel composite plating, explosive bonding, electrodeposited nanocrystalline cobalt-phosphorus alloys and physical vapour deposition (PVD) coatings. To date, HVOF and other spray coatings have been considered the best available alternative to HCP. However, Hardide-A provides several advantages over HVOF such as versatile geometric compatibility, corrosion and fatigue resistance and facilitated finishing.
Philip Kirkham, Chief Executive Officer of Hardide Coatings said: “Hardide-A provides comparable or better performance over hard chrome with none of the environmental issues. We are working on test programmes with customers including AgustaWestland, Airbus and other aerospace OEMs (original equipment manufacturers).”
The company has successfully completed the first of two test phases to approve Hardide-A as a replacement for HCP on an application for AgustaWestland, and, if successful, the Hardide coating will be approved for use on a specific AgustaWestland helicopter rotor blade component. The helicopter manufacturer is also considering other applications for the Hardide coating technology.
The Hardide coating has featured positively as an alternative for hard chromium plating for severe service valves in a peer-reviewed article* in Elsevier’s Materials Chemistry and Physics, the international journal on science, characterisation and processing of advanced materials. The July 2013 article was independently authored by valve manufacturer Velan Inc, the Université de Montréal and Notre Dame University-Louize, Lebanon. *Published as “L.Vernhes, et al., Alternatives for hard chromium plating: Nanostructured coatings for severe-service valves, Materials Chemistry and Physics (2013)” and available to purchase at http://dx.doi.org/10.1016/j.matchemphys.2013.03.065.