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For the past decade, environmental regulations and global initiatives including REACh and ELV have resulted in an increase in Research and Development (R&D) spending for many global companies. COVENTYA has not abstained from these type investments to support our global business.

Additionally, innovation today in plating and surface finishing applications is less frequent unless your R&D teams are challenged to develop a technology for replacing a legacy technology; in this case a 100 year old, industrial and production proven plating system Functional Chrome.  In one example, over the past decade especially, environmental initiatives have required our industry to invest into R&D programs to address environmental concerns of hexavalent chromium.

Regulations, including those coming from REACh, the Clean Air Act and Clean Water Act, give requirements and allowances for the use of hexavalent chrome for plating applications and setting limits as to how much hexavalent chrome is permitted for discharge into the environment.

In the USA, these laws are enforced by the United States Environmental Protection Agency (EPA) who set the standards, and in 2012 accepted the input from the National Association of Surface Finishers to ban the use of PFOS/PFOA long chain carbon-fluorine compounds which Cr(VI) systems require for the proper control of their emissions into the air. In Europe, PFOS compounds have been forbidden since 2008 and PFOA compounds have had restrictions since 2017 that supported our programs to eliminate their use in any future technologies. Most recent law proposals in Europe envisage a full stop of all remaining exceptions (including Hard Chrome) by 2025, thus eliminating hexavalent chrome plating for good in view of lacking alternatives.

Globally recognized, Hard Chromium plating, better known as Functional Chrome plating, the COVENTYA CHROME 450 technology for example, was an important target for replacement.  Environmentally this type chemistry has a high level of awareness for its hazardous nature due, not only, to hexavalent chromium concerns and impacts including wastewaters, emissions into the air, but also several other targets including avoiding the use of carbon-fluorine compounds. These carbon-fluorine compounds are persistent, bio-accumulative and toxic and the current movement to re-evaluate the types required for Cr(VI) mist/fume suppression are being targeted.

The CHROME 450 type applications using lead anodes is an additional source for contamination to the environment that was important to address in any replacement technology target.

However, with functional chrome for a plated deposit, the success for engineering advantages and benefits including high hardness, resistance to abrasion, long part/component durability from the high wear resistance and low friction have been important for many critical applications across the aircraft industry, hydraulic equipment industry and many others.

All these negative issues with the Cr(VI) type systems become a concern of the past with successful completion of an R&D project introduction of a trivalent hard chrome electrolyte and system.

In 2014, COVENTYA realized a viable way for developing a non-hexavalent chromium-hard chrome plating electrolyte.  During this period since, we have advanced the technology for commercialization and over the past year have been in the industrialization of this new technology platform.

Known as the DURATRI 240 Cr(III) plating system, the resulting deposits meet or in some cases even exceed the engineering demands of existing Cr(VI) commercialized hard chromium deposits

  • REACh compliant chemistry including boric acid free electrolyte
  • No carbon-fluorine (PFAS) compounds used which is required for Cr(VI) electrolytes for meeting PEL requirements.
  • Plating uses lead-free anodes which are necessary for Cr(VI) plating.
  • Chrome plated thickness ability up to 500 µm which meets Cr(VI) requirements.
  • Deposit hardness ranges from 800 up 1000 HV100 similar to Cr(VI) deposits without heat treatment.
  • Abrasion Wear by Taber methods (TWI) meets 1 – 3 mg/loss per 1000 cycles similar to Cr(VI) deposits.
  • Chemistry operates at 23 – 25 g/L of Chrome metal, dilute vs Cr(VI) plating systems and less metal for waste treatment.
  • Operating pH is 5.0 – 5.5 which is much less corrosive and acidic to Cr(VI) chemistry

The DURATRI 240 demonstrates similar deposit characteristics, and test data for resulting fatigue strength is better than Cr(VI) deposits which is especially critical for aircraft and aerospace applications or other engineering systems that require high performance and reliability.

Table 1: Summary Deposit Properties Comparison Cr(VI) to Cr(III)
PropertiesCHROME 450 CrVI coatingsDURATRI 240
coatings
Hardness800 – 1150 Hv0,05800 – 1000 Hv0,05
AppearanceBright to dullBright to dull depending on plating conditions
MorphologyMicro cracks fissuresAlmost no visible cracks after plating, but present after Thermal Treatments
Taber abrasion
Taber Wear Index
(mg loss/1000 cycles)
TWI 1 – 3TWI 1 – 3 with or without thermal treatment.
Corrosion resistanceClose to 96 hours NSSTNot sufficient without Nickel under-layer.
Fatigue resistance400 MPa at 107 cycles500 MPa at 107 cycles
Temperature effectDecreases hardnessIncreases hardness, up to 1500 HV, widens deposit cracks
Deposit Composition Cr – 99% mass
C – <1% mass
O – < 1% mass
Cr – 93 – 94% mass
C – 3 – 4% mass
O – < 1% mass

Operationally, the DURATRI 240 require some other important differences to Cr(VI) type chemistry.  Traditional methods of surface preparation for functional chrome must be modified to successfully plate Cr(III) deposits.  One common practice to “reverse” etch many types of substrates in the Cr(VI) plating electrolyte must be avoided with the DURATRI 240 or any electrolyte based on Cr(III) chemistry.  The very acidic, low pH characteristic of the Cr(VI) allowed applicators for reverse etching as activation step, where the pH 5.0 – 5.5 Cr(III) chemistry electrolyte will not offer any benefit for reverse etching, and in fact, this type is more sensitive to contamination from that practice.  Successful applications of DURATRI 240 require surface preparation sequences similar to those for Electroless Nickel, including soak cleaning, electrocleaning, acid activation depending on substrate type and nickel activating strike for many high strength alloy types. For some existing Cr(VI) applicators, the changeover to this type technology platform will be a challenge because of the different requirements for equipment, and methodology of application compared to traditional applications for Cr(VI) deposits.  Process tanks, rectification and other equipment will need to be redesigned to accommodate the installation of a DURATRI 240 Cr(III) technology. This is the reason why COVENTYA is currently actively pursuing the industrialization phase of DURATRI 240 in different applications. First production lines have been started. The COVENTYA team will gladly sit down with you to discuss your current or future application requirements for Functional Chrome and provide some samples of the deposit on your parts for testing and evaluation.

COVENTYA does not stop with the DURATRI 240 Cr (III) technology development. Our company maintains an active R&D program called CRONOS 2024 started in October 2018 in the framework of the French IRT M2P program that includes 17 industrial partners and 2 academics, with two primary focus objectives.

The first one is to provide to the interested parties the ability to process representative parts with DURATRI 240 chemistry in the pilot and industrial lines of IRT or its affiliates and implement the process in their facilities. The second objective is to evaluate the ability of the chemistry to be modified or redesigned for fulfilling specific requirements for high end applications including those in Aerospace and Defense sectors that cannot be currently met with the first generation chemistry.  This is why our evolution of innovation at COVENTYA remains an important goal of our company.

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