Accession Number:

AD1064242

Title:

Electrodeposited Nanocrystalline Co-P Alloy Coatings as a Hard Chrome Alternative

Descriptive Note:

Technical Report,01 Oct 2009,01 Dec 2014

Corporate Author:

Naval Air Systems Command FRCSE Jacksonville

Report Date:

2017-09-05

Pagination or Media Count:

60.0

Abstract:

The replacement of hard chrome plating in aircraft manufacturing activities and maintenance depots is a high priority for the U.S. Department of Defense. Chromium plating baths contain chromic acid, in which the chromium is present in the hexavalent state Cr6, a known carcinogen having a high level of toxicity. Nanocrystalline cobalt-phosphorus nCoP is an environmentally benign alternative to engineering hard chrome plating EHC. The nCoP coatings are applied to both line-of-sight and non-line-of-sight surfaces using similar electroplating processes. This program aimed to qualify to the technology for use in applications currently specified for EHC. Overall, nCoP met the majority of acceptance criteria as defined in the Joint Test Protocol and showed excellent performance in demonstration and validation field testing. The results showed that nCoP exceeded EHC performance in corrosion and sliding wear tests. The abrasive wear performance of nCoP by Taber wear was poor as previously determined, while gravelometry testing showed equivalent performance relative to hard chrome. Fatigue and hydrogen embrittlement testing showed nCoP met or exceeded performance of EHC. While further testing may be required to support General authorization, it is anticipated that nCoP may be widely specified per MIL-DTL-32502 - Coating, Cobalt-Phosphorus Alloy, Nanocrystalline Electrodeposited as a hard chrome alternative on the basis of testing completed to date.

Subject Categories:

  • Properties of Metals and Alloys
  • Coatings, Colorants and Finishes
  • Mechanics
  • Aircraft
  • Properties of Metals and Alloys
  • Coatings, Colorants and Finishes
  • Mechanics
  • Aircraft

Distribution Statement:

APPROVED FOR PUBLIC RELEASE