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re: Chromate Conversion Coating


This repsonse is from the P2TECH archives (Monday November 6, 1995).
This report is a good resource. You may also want to try the National Metal
Finishing Resource Center (NMFRC)
at www.nmfrc.org

NCMS Project 17-0403, Alternative to Chromium for Metal Finishing, has 
completed its work.  The project deals with evaluating chromium-free 
alternatives for conversion coating of aluminum alloys. Project participants 
have agreed to release the final report to the general public.

Certain chromium containing compounds used in metal finishing processes have 
been identified as potential human carcinogens.  As a result, both usage of 
these compounds in the workplace and disposal of wastewater and sludges 
containing these compounds are becoming increasingly problematic.  Many 
current users of chromium in metal finishing processes have been seeking 
alternative coatings.

A number of suppliers have developed chromium free alternative coatings, but 
until now there has been no good reference for determining how these 
alterntaives perform on a variety of standard tests.  During the course of 
the NCMS project, participants obtained samples of 29 chromium free 
coatings, plus four standard chromium controls, on test panels of five 
different aluminum alloys.  These panels were tested side-by-side on three 
performance measures:  salt-spray corrosion resistance, contact electrical 
resistance, and paint adhesion.  The detailed results of these tests are 
compiled in the final project report.

In addition, one of the project participants (Rensselaer Polytechnic 
Institute) carried out an environmental impact analysis of the alternatives, 
compared with a standard chromium baseline.  This analysis is also included 
in the report.

The report is unique in its level of detail, and in the degree of 
intercomparability made possible by the test protocols used in the study. 
 It is of interest both for the specific information it provides on 
alternatives for conversion coating of aluminum, and as a model for the 
collaborative process in general.  The framework provided for setting up an 
environmental impact analysis may also be of interest outside the particular 
focus of the study.

Copies of the final report may be ordered from MIRC for $25 per copy, plus 
$5 per copy shipping and handling.  Contact Kim Richardson at (313) 995-3068 
for details.

Recomended by:

Paul Chalmer
National Metal Finishing Resource Center
3025 Boardwalk Drive
Ann Arbor, MI 48108-3266
phone:    (313) 995-4911
fax: (313) 995-1150

David S. Liebl
University of Wisconsin - Solid and Hazardous Waste Education Center
610 Langdon Street,  Madison, WI  53703-1195
608/265-2360 FAX 262-6250   liebl@epd.engr.wisc.edu

Good Luck,

Jeff Lewis
Ohio EPA/Office of Pollution Prevention
P.O. Box 1049
Columbus, OH 43216
phone: (614) 644-2812
email: jeff_lewis@central.epa.ohio.gov