2014 SERDP Project-of-the-Year Award for Weapons Systems and Platforms

Hazardous solvents and cadmium plating for the maintenance and overhaul of military weapons systems have been primary environmental concerns of the DoD for many years. Both of these areas have a common obstacle for implementation of any potential alternative—hydrogen embrittlement, which can lead to fracturing of high strength steel. 

High strength materials are sensitive to hydrogen embrittlement, and the source of the hydrogen can be the fabrication process, maintenance practice, or the natural corrosion cycle. Historically, the various aerospace defense contractors have each tested hydrogen embrittlement in their own manner, which has led to a national standard incorporating many approved test geometries and somewhat ambiguous procedures. The standard method is a pass/fail test, and the ambiguous procedures lead to conflicting test results and perceived risk and roadblocks to implementation of proposed alternative chemicals and coatings. 

In this SERDP-funded project, Mr. Scott Grendahl of the U.S. Army Research Laboratory and his team used a three-phase design of experiments approach to investigate the hydrogen re-embrittlement effects of common aviation maintenance chemicals and coatings. Both material and geometry were examined to uncover the best constraints for a novel test method. While traditional testing uses a pass/fail approach, the newly developed method employs load monitoring cells over a range of material strength, hydrogen emitting environment, and applied load, allowing prospective solvent replacement chemicals and cadmium replacement coatings to be finely delineated in terms of performance. The team also developed a modeling-based tool for predicting time to failure under any combination of parameters. 

A major benefit of this research will be the removal of implementation hurdles related to hydrogen embrittlement for alternative chemicals and coatings, easing the restriction in the aviation community on the use of alternatives and expanding their applications on high strength steel. The results from this project also led to refining the language of the ASTM Standard

Results from the specimen geometry life prediction models for AMS-6415 steel. The x and y axes are applied load and NaCl concentration, respectively, while the z (vertical) axis represents time to failure. Flat portions indicate no failure within 168 hours.

For this instrumental work, Mr. Grendahl and his project team received the 2014 SERDP Project-of-the-Year Award for Weapons Systems and Platforms. Project Overview 

Project Team 

• Mr. Scott Grendahl, U.S. Army Research Laboratory
• Mr. Hoang Nguyen, Bowhead Science and Technology LLC
• Boeing Research & Technology 
  • Dr. Shuying Zhu
  • Dr. Stephen P. Jones 
  • Ed A. Babcock
  • Dr. Joseph H. Osborne 
  • Stephen P. Gaydos
• Mr. Chad Hogan, U.S. Air Force
• Mr. Richard Green, Green Specialty Service Inc.
• Mr. David Kelly, Asko Processing Inc.

Information provided courtesy of https://www.serdp-estcp.org

Nanocrystalline Coatings Provide Hard Chrome Alternative

Implementation of ESTCP-demonstrated electrodeposited nanocrystalline cobalt-phosphorus (nCoP) coatings on military aircraft will eliminate environmental and worker safety concerns associated with hexavalent chromium used in DoD plating operations, and reduce operational costs. 

Replacement of hard chromium (Cr) plating in aircraft manufacturing activities and maintenance depots is a high priority for the DoD. Hard chrome plating is a critical process that is used extensively within military aircraft maintenance depots for applying wear and/or corrosion resistant coatings to various aircraft components and for general re-build of worn or corroded parts during repair and overhaul. However, hard chrome plating baths contain hexavalent chromium, a known carcinogen. Wastes generated from these plating operations must abide by strict EPA emissions standardsand OSHA permissible exposure limits (PELs). The operational costs to comply with these rules and the increased turnaround times for processing of components require DoD to find an environmentally benign alternative to hard chrome. 

Mr. Ruben Prado and Mr. John Benfer of NAVAIR Jacksonville, together with their team, demonstrated that nCoP meets the majority of acceptance criteria for coating quality, adhesion, fatigue, corrosion, hydrogen embrittlement, fluid compatibility, wear, and impact testing for a wide variety of applications. Based on testing to date, the team anticipates that nCoP will be widely specified per MIL-DTL-32502 as a hard chrome alternative.

For this significant work, Mr. Prado, Mr. Benfer, and their project team received the 2014 ESTCP Project-of-the-Year Award for Weapons Systems and Platforms. Project Overview 

Project Team

• NAVAIR Jacksonville
  • Mr. Ruben Prado
  • Mr. Jack Benfer 
• NAVAIR Patuxent River 
  • Mr. Steve Brown
  • Mr. Craig Matzdorf 
• Mr. Michael Firth, NAVAIR Lakehurst
• Mr. Robert Kestler, NAVAIR Cherry Point
• Ms. Denise M. Aylor, NSWCCD
• NAVAIR Jacksonville 
  • Mr. Richard Polinsky
  • Ms. Luzmarie Youngers
  • Mr. Peter Sheridan
  • Ms. Mikaleen Morrell
• CNATRA Det Meridian 
  • Mr. Sean Whitney
  • Mr. Hector Perez
• Mr. Stephen Gaydos, Boeing Research and Development
• Mr. Jerry Curran, NASA Corrosion Technology Laboratory
• Dr. Keith Legg, Rowan Technology Group
• Mr. Neil Mahalanobis, Integran Technologies, Inc.

Information provided courtesy of https://www.serdp-estcp.org