Trivalent vs. Hexavalent Chromium

Decorative trivalent chromium processes Has been used in the decorative market globally for over 40 years. With the upgrading of the hazard level of hexavalent chrome processes as a CMR source, a comparison of the processes is of interest. The major benefit of Trivalent chromium processes is that they are much more versatile. These benefits are summarized below:

  • All trivalent chromium processes have complete tolerance to current interruption. If the power goes off when plating in a hex bath you need to strip and replate, with tri you can just continue.
  • Due to the processes higher efficiency, low current density areas are covered more completely.
  • Barrel plating with trivalent chrome is possible, you cannot do this with hexavalent chrome.
  • Distribution is much more uniform.
  • Used with ion exchange, the process offers excellent resistance to metallic contamination.
  • Chemical purification along with dummy plating are also methods used widely to control contaminants.
  • More wear and corrosion resistance compared to hexavalent processes - ~ 20% more in both areas
  • Lower hardness than hexavalent chrome - 600-800 against 700-950 Hv
  • Good performance in automotive corrosion protection - In excess of 450 hrs NSS and 72 hours CASS from well managed process
  • Trivalent deposit appearance is different to hexavalent chrome - Slightly darker and not as blue
  • But there is now a process in the market that is almost identical in color to hexavalent chromium

See below 2 pictures depicting the different appearance of the deposits:

Spectral image of the comparison between Hexavalent and Trivalent chrome using Hunter Labs ColorQuest XE Colorimeter: