Surface Engineering and Structural Materials

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To maintain military readiness and reduce maintenance costs, weapons systems must be protected from environmental degradation. This is usually achieved through the use of various types of surface engineering technologies. In addition, structural materials on weapons systems generally must possess unique properties in order to function in a demanding operational environment. Providing protection from environmental degradation or manufacturing and maintaining structural materials with unique properties has often required the use of toxic or hazardous chemical substances. SERDP and ESTCP are developing and demonstrating the science, tools, and techniques needed to meet critical defense performance criteria while also reducing the impact on the environment and protecting the health of DoD workers and military personnel.

The Department of Defense is committed to reducing the use of hazardous and toxic materials and minimizing the associated risks in the manufacturing and maintenance of weapons systems. SERDP and ESTCP investments focus on the following areas:

Coatings, Sealants and Adhesives

  • Coatings – Coatings are the most widely used method for providing corrosion protection, but for decades the best performing coatings have contained hexavalent chromium, cadmium and volatile organic compounds (VOCs). Projects are focused on developing and demonstrating alternative coatings which do not require these toxic materials. Investments are targeted to conversion coatings, primers, sacrificial coatings, hard chrome or cadmium plating, and top coats.
  • Sealants – Sealants are used to provide an electrically insulating, corrosion-resistant barrier between dissimilar metals. The preferred corrosion inhibitors for aerospace sealants have historically been compounds containing hexavalent chromium. In many cases, these contain high VOC solvents that are necessary for proper processing and curing. Projects are focused on developing and demonstrating alternative sealants that do not contain these hazardous materials.
  • Adhesives – Adhesives are used for repair of composite materials that can be damaged in service. Maintaining corrosion resistance at the bond line is critical to maintaining performance, but this is often achieved through the use of adhesive bond primers that contain hexavalent chromium. Projects are focused on developing and demonstrating alternative sealants that provide protection from corrosion without the use of hexavalent chromium.

Surface Cleaning

Chemicals and processes used in surface cleaning in many cases involve toxic materials and produce volatile emissions. Projects are focused on developing and demonstrating environmentally friendly alternative chemicals and processes that still provide the same cleaning ability as currently used solvents and drop-in replacements for common practices like vapor degreasing. 

Non-Destructive Inspection

Maintenance activities generate potentially hazardous waste and require some level of worker protection. One method for reducing emissions and mitigating worker safety concerns is to reduce the amount of maintenance that is required. For example, without adequate inspection techniques, coatings that could be returned to service are instead stripped and the surfaces re-coated. Projects are focused on developing new technologies for non-destructive inspection that could reliably determine if coatings needed to be removed.

Coating Removal

Maintenance operations can involve the removal of previously applied coatings using hazardous chemicals or exposing workers to hazardous materials contained in the coatings. Projects are focused on developing materials and processes that avoid using hazardous chemicals, limit worker exposure, and reduce coating removal costs. Current processes use harsh chemicals or an abrasive media to remove coatings, which is labor and media intensive.

Composites, Alloys, and Ceramics

  • Composites – Composite materials are used across DoD because of their light weight, high strength, and corrosion resistance. These properties often make them the materials of choice for aircraft, electronics, structures, and personnel protective armors. Many materials used in composites, however, are produced with fossil fuel feedstocks and contain volatile organic compounds and hazardous air pollutants. In addition, the repair of composites often requires the use of hazardous materials. Projects work to develop new composite materials made from renewable feedstocks and new environmentally friendly composite repair methods that reduce waste and do not contain hazardous materials.
  • Alloy Development – Some alloys used in structural components on weapons systems contain highly toxic metals such as beryllium. In other cases, because the alloy used in a structural component in highly susceptible to corrosion, a toxic metal such as cadmium is used as a coating to provide corrosion resistance. In that case, an alternative to developing new coatings is to design and manufacture new alloys that have the same mechanical properties and improved corrosion properties. Projects are focused on developing new alloys that do not require toxic elements but still satisfy performance requirements.
  • Ceramics – The use of ceramics for applications such as armor is increasing in the military. Manufacture of these materials often results in the release of volatile organic compounds and greenhouse gases. Projects are focused on developing new manufacturing methods that reduce these types of emissions.

Welding and Joining Technologies

Welding operations can expose workers to hazardous fumes. Projects have focused on developing new chromium-free welding rods that result in welds with the required mechanical properties and on developing new techniques for reducing fume generation to reduce worker exposure.

FY 2020 New Start Project Selections

FY 2020 New Start Project Selections for the Environmental Solicitation – SERDP; ESTCP

DoD’s Chemical and Material Risk Management Directorate

DoD Policy Memo:
Minimizing the Use of Hexavalent Chromium (Cr6+)


Impact of European REACH Regulations: 2015 Update

Cold Spray Cost Benefit Analysis

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