INTRODUCING

CHEMEON eTCP®

The first trivalent conversion coating and anodic seal with distinct color for visual verification that your parts are coated and protected

INTRODUCING

CHEMEON eTCP®

The first trivalent conversion coating and anodic seal with distinct color for visual verification that your parts are coated and protected

INTRODUCING

CHEMEON eTCP®

The first trivalent conversion coating and anodic seal with distinct color for visual verification that your parts are coated and protected

The Road to Replacement:
Removing Hexavalent Chromates for CHEMEON eTCP®

Chromates (Cr+6) have been extremely effective and have been extensively used as corrosion inhibitors for ferrous and non-ferrous alloys in aerospace, military and general industry applications for many decades. However, solutions containing hexavalent chromate-based compounds are highly toxic and adversely affect the environment and human health. In fact, many government and regulatory agencies — including the U.S. Environmental Protection Agency through the Clean Water Act (CWA) and the Toxic Substances Control Act (TSCA), the Occupational Safety and Health Administration (OSHA) and the European Union (EU) — have demonstrated the desire to eliminate the release of chromates during coating applications, forcing OEMs and their suppliers to seek alternative and safer products.

The Dangers of Hexavalent Chromates

Hexavalent chromium products are carcinogenic substances, and are hazardous to human health and environment. They leach into the grounds and cause damage, and are thus prohibited in many uses due to its toxic nature. Environmental guidelines and regulations have been in place for several years to restrict and prohibit its usage. Materials containing Cr+6 include various paint and primer pigments. An estimated 558,000 U.S. workers are exposed to airborne Cr+6 compounds in the workplace each year. The National Institute for Occupational Safety and Health recommends that airborne exposure to all Cr+6 compounds be limited to a concentration of 0.2 µg Cr+6/m3 for an 8-hr time-weighted average (TWA) exposure, during a 40-hr workweek. NIOSH further recommends that continued efforts be made to reduce exposures to Cr+6 compounds below the REL.

Ensuring Worker Safety and Meeting Guidelines

For more than half a century, the finishing industry standard for conversion coating of aluminum aircraft components and surfaces was pretreatments that utilized hexavalent chromium. The result was an iridescent golden color change for ease of inspection, but the chromate was targeted to be removed because it was a known carcinogen and environmental pollutant.

Chemical conversion coatings are adherent layers of low solubility oxide, chromate compounds produced on the surface of aluminum that converts the metal surface to a non-metallic inert state. These coatings are produced by a chemical oxidation-reduction reaction, with the main function to act as an undercoating and a base for organic finishes, as well as provide corrosion resistance and improve adhesion of paint finish systems on aluminum alloys. For decades, the industry searched for a “next generation” enhanced trivalent chromium pretreatment coating (eTCP) that was an environmentally safer alternative to hex chrome, and was also easy to inspect through color change. Several attempts came close to an alternative trivalent chromium undercoat that was safer, but they did not provide the obvious color change seen with hexavalent chromium, which could lead to difficulty identifying the presence of coatings for quality control purposes.

The Need for an Enhanced Trivalent Chromium Pretreatment (eTCP)

The Naval Air Systems Command (NAVAIR) and the Fleet Readiness Center Southeast (FRCSE) several years ago decided to push further the development of a replacement for hexavalent chromium, which they called enhanced trivalent chromium pretreatment, or eTCP. The goal was to develop a product that satisfied several criteria from a performance and health standpoint:

  • Reduced hexavalent chromium usage.
  • Elimination of hexavalent chromium reduction requirements for conversion coat rinse water.
  • Reduced occupational exposure to hexavalent chromium.
  • Reduced risk of hexavalent chromium migration to adjacent work centers.

The overall objective was complex in that it also needed the addition of dye to the chemistry to reduce implementation barriers. The benefits to NAVAIR and FRCSE were that it lowered the potential for quality escapes through visual verification of proper coating application, which decreases turnaround time through elimination of rework due to improper coating application.

Development of CHEMEON eTCP® in Coordination with NAVAIR, FRCSE

Starting in 2016, the research teams at CHEMEON, NAVAIR and FRCSE researched and tested the processes to validate results, mitigates risks of processing volume and coating uniformity, and selected a final range of concentrations to evaluate. Over the next three years, the researchers processed test panels testing for corrosion resistance, paint adhesion and color change, while documenting results in numerous interim reports that brought some excitement to the finishing industry.

In 2018 and 2019 several breakthroughs by the CHEMEON research staff began to take hold.

The end result was the NextGen pretreatment CHEMEON eTCP a patented formulation that exceeds MIL-DTL-5541 and MIL-DTL-8170 requirements for corrosion protection, electrical resistance and adhesion and provides a visual color indicator that parts are coated and protected.  Learn more about the Power of Protection You Can See®.