Final Report: A Cost-Competitive Functional Trivalent Chromium Plating Process To Replace Hexavalent Chromium PlatingEPA Contract Number: 68D00274
Title: A Cost-Competitive Functional Trivalent Chromium Plating Process To Replace Hexavalent Chromium Plating
Investigators: Renz, Robert P.
Small Business: Faraday Technology, Inc.
EPA Contact: Richards, April
Project Period: September 1, 2000 through September 1, 2002
Project Amount: $225,000
RFA: Small Business Innovation Research (SBIR) - Phase II (2000) Recipients Lists
Research Category: Small Business Innovation Research (SBIR)
In this research project, Faraday Technology, Inc., deployed electrically mediated
electrochemical deposition in conjunction with a cost-competitive trivalent
chromium (Cr+3) plating chemistry. This process
is termed the "Faradaic Process." The resulting innovation will
be a reduced-cost, performance-based Cr+3 plating process to replace conventional
hexavalent chromium (Cr+6) plating.
A detailed analysis of trivalent chrome plating bath chemistry was conducted. Bench-scale rotating disk electrode studies were conducted to qualify the trivalent chemistry with the Faradaic Process parameters in a controlled hydrodynamic environment. A controlled Alpha test of the Faradaic Process was completed in a pilot-scale manufacturing cell designed and built by Faraday. This test was conducted using strut rods provided by a Tier 1 automotive supplier.
The Faradaic Process was shown to be comparable to conventional Cr+6 plating for equivalent hardness, coating thickness, plating rate, and consumable cost. Cr+3 is considered to be a class A carcinogen (not carcinogenic to the human body), whereas Cr+6 is considered to be a class D carcinogen (carcinogenic to the human body).
The prior art has been assessed regarding the electrodeposition of functional chromium coatings from a trivalent bath. The prior art search identified two patents awarded to the National Institute of Standards and Technology as the closest prior art. Based on innovations from this research project, a patent application will be filed, and it is anticipated that the patent application will not "read on" the prior art.
Applications for the Faradaic Process are enormous (i.e., anywhere hard chromium coatings are desired). This Phase II research project generated $219,723 in commercial sales. The project will continue beyond the completion of the Phase II contract for ongoing alpha testing of pump rotors for a prominent manufacturer of industrial products.
Below is a summary of work generated by this project that Faraday is committed to completing:
· Concurrent Technologies Corporation (CTC). Faraday was invited to participate in Phase II of the Functional Trivalent Chromium Plating Task. Table 1 lists the scheduled tests that CTC will perform during Phase II, the required sample size for each test, and the required quantity for each coating scenario Faraday is applying that must be shipped back to CTC for each test.
|Test||Sample Size||Sample Quantity To Be Returned to CTC|
|Corrosion Resistance||4" x 4"||3|
|Taber Abrasion||4" x 4" with hole in center||3|
|Pin-on-Disk Wear*||2" x 2"||3|
|Adhesion, Microcrack Analysis||2" x 2"||2|
· U.S. Navy. Faraday will be supplying the U.S. Navy with 1/2" hardened and ground steel that has been plated with ~125 µm (5 mils) of chromium per side. The U.S. Navy will evaluate these coatings for potential use in their plating facilities.
· Commercialization Partner. Faraday will be chromium-plating rotors a commercialization partner's pumps. The pumps are widely used for pumping abrasive solutions, and the surface on the rotor is the main reason for pump life. The commercialization partner submitted hardened and ground steel and stainless steel rotors for this purpose. These rotors will be tested in pumps at their facility, where they have extensive data on the wear characteristics of various coatings being considered as replacements for their current chromium plating process that uses Cr+6.
A pilot-scale chromium plating line is being operated at the Faraday facility in Clayton, OH. This plating line is a small-scale version of a shop-floor full-scale line (see Figure 1). This line is being used to validate the Faradaic Process on shock rods and pump rotors as depicted in Figure 2.
Figure 1. Complete functional trivalent chromium plating line, including pre-clean, electrolyte chiller, plating tank, and power supply.
Figure 2. Pump rotor (above) and shock rod (below) are being used to validate the Faradaic Process.