Physical Vapor Deposition (PVD) Coatings and ION Beam Processing as Alternatives to Electroplating

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Project Title: Physical Vapor Deposition (PVD) Coatings and ION Beam Processing as Alternatives to Electroplating

Date Last Updated: 11/96

Project Summary: Hard chrome is primarily used in Department of Defense related manufacturing to 1) coat high-wear surfaces such as bearing shafts and hydraulic components and 2) rebuild and remanufacture out-of-tolerance components, such as worn shafts and corroded hydraulic components. Cadmium electroplating is also used to impart corrosion resistance and lubricity to a wide variety of parts, although substitute coating processes have been more fully developed for this than for the hard-chrome plating. The goal of this project is to conduct applied research and development to demonstrate that metal or ceramic coatings deposited by physical vapor deposition (PVD), and/or ion-beam-modified surfaces are equivalent or superior in performance and are a cost-effective and environmentally acceptable alternative to electroplated chromium and cadmium for military applications. If successful, this research will eliminate or reduce the usage of environmentally harmful chrome and cadmium electroplating processes.

These two technologies are already known to be environmentally acceptable, so the focus of this project will be the characterization and evaluation of the coatings in comparison to electroplated chromium and cadmium coatings. Evaluation of coating performance must include laboratory simulation of the conditions to which coated components will be subjected in battlefield and global environments, with a baseline comparison with hard-chrome coated components. Properties such as hardness, adhesion, and density will be determined for all of the coatings. Measurements related to actual performance will be correlated with the type of electroplated coating intended to be replaced and the actual end use application. Thus, testing will include 1) sliding wear tests with realistic loads, speeds, and use of lubricants, 2) erosion tests, 3) corrosion tests using electrochemical and/or salt spray methods, and 4) low-cycle or high-cycle fatigue, or rolling-contact fatigue, and 5) hot-hardness tests. In addition to evaluation of coated test coupons, actual components will be selected for coating and evaluation.

A recent study showed a Zn-Ni alloy provided better resistance than zinc and exhibited a comparable coefficient of friction. While the Cd plating alternatives have reached a certain degree of maturity, several issues still need to be resolved. Problems to be addressed include: fatigue and Environmentally Assisted Cracking , torque-tension requirements for fasteners (before and after exposure), close tolerances, and ability to reach recessed areas. Thus there still exists the need for further coating development & characterization efforts. To date, several of the coatings applied have shown wear, adhesion, and corrosion properties equivalent or exceeding that of hard chrome plate. Selection of components for coating in 1996 has proceeded on schedule.

Project Keywords: hard chrome, physical vapor deposition, metal coatings, ceramic coatings, electroplated chromium, ion-beam-modified surfaces, zinc alloys, tin alloys

Organizing Performing Research: US Army

Primary research Contact:
Dr. John H. Beatty, AMSRL-MA-CC, Army Research Laboratory,
Materials Directorate, 102 MD Hall, Johns Hopkins University,
Baltimore MD 21218
PHONE: (410) 516-4748
FAX: (410) 516-5293
E-MAIL: jbeatty@arl.mil

Dr. Bruce D. Sartwell, Surface Modification Branch, Naval Research
Laboratory, Code 6675, Washington, DC 20375-5345
PHONE: (202) 767-0722
FAX: (202) 767-3321

Date research Started/Completed: 11/94 - 10/96

Publications Based on Research: none available

Approximate Project Budget: $1,520,000

Primary Project Funder: Strategic Environmental Research & Development Project (SERDP)

Funder Contact:
Dr. Robert Holst
Program Manager for Compliance and Pollution Prevention
SERDP Program Office
901 North Stuart Street, Suite 303
Arlington, VA 22203
phone: (703) 696-2125
fax: (703) 696-2114
e-mail: holstrw@acq.osd.mil