- Program Areas
- Installation Energy and Water
- Environmental Restoration
- Munitions Response
- Resource Conservation and Resiliency
- Weapons Systems and Platforms
- Energetic Materials and Munitions
- Noise and Emissions
- Surface Engineering and Structural Materials
- Fuels and Greenhouse Gases
- Lead-Free Electronics
- Waste Reduction and Treatment in DoD Operations
Environmentally Friendly Zirconium Oxide Pretreatment
Fred Lafferman | U.S. Army Research Laboratory
There is a need to implement innovative and cost effective replacement technologies to address the multiple health, safety and compliance issues associated with the current systems while maintaining military readiness for national defense. In addition, the new technology must have the following attributes: 1) compatibility with original equipment manufacturers (OEM)/Depot infrastructure, 2) corrosion performance equivalent to (or better than) current phosphate based pretreatments, 3) broad compatibility with the current suite of military coatings and, 4) compatibility with substrates used by the Department of Defense (DoD). The objective of the program is to demonstrate a novel pretreatment technology in relevant DoD environments. The zirconium based pretreatment will be shown to be environmentally acceptable, (no Hazardous Air Pollutants [HAP] or heavy metals such as Cr6+ or Ni), and a cost effective alternative to existing phosphate based pretreatments. At the conclusion of the program plan, the zirconium based pretreatment will have been demonstrated to perform equal to (or better than) existing phosphate based pretreatments while offering compatibility with the current suite of military coatings and a range of ferrous and non‐ferrous substrates.
The zirconium based pretreatment was originally developed by PPG Industries for the automotive industry where it is providing corrosion protection equivalent to zinc phosphate on a variety of substrates (including cold rolled steel). The technology provides a high‐quality, continuous zirconium‐based pretreatment on multiple types of ferrous, zinc and aluminum substrates by immersing the metal into a dilute solution of fluorozirconic acid (FZA) and proprietary additives at ambient temperature for 30 to 120 seconds. The dilute, aqueous FZA pretreatment bath is only slightly acidic (pH=4.5) and does not contain volatile organic compounds (VOC). During the treatment process, the substrate is etched slightly which results in a pH increase at the substrate/solution interface. This change in pH results in the precipitation and subsequent bonding of zirconium oxide and additives to the surface of the substrate. The chemistry enables a zirconium‐based technology that does not contain any regulated heavy metals such as chromium or nickel.
Zirconium‐based metal pretreatment technology is an alternative to conventional technologies such as zinc phosphate, chromate‐containing etch primers, and chromate conversion coatings. Compared to these conventional technologies, zirconium‐based pretreatments can provide the following advantages:
- Operation under ambient conditions versus >125 °F for metal phosphate systems.
- Reduction in the amount (80% less) and toxicity of waste materials generated from pretreatment application and disposal processes.
- Reduction in water use in the pretreatment process.
- Reduced exposure to toxic and regulated materials during the pretreatment process.
- Reduced deposition of metallic compounds such as chrome that could be released during rework and other downstream operations.
(Anticipated Project Completion - 2016)