The objective of this Statement of Need (SON) was to develop a rapid curing, non-isocyanate erosion-resistant coating containing low to no volatile organic chemicals (VOCs) or hazardous air pollutants (HAPs). This coating must have met or exceeded critical performance properties specified in SAE AMS-C-83231 Revision A to include peel strength, flexibility, water resistance, aromatic fuel resistance, rain erosion resistance, electrical transmission, surface resistivity, weather resistance, and strippability (see Table 1 in the Appendix below). In addition, resistance to lubricating oil and hydraulic fluid degradation was desirable (see Table 2 in the Appendix). Proposals for use of alternative materials must have included a preliminary toxicological assessment of the alternative materials.

Implementing the new coatings envisioned in this SON at radar dome (radome) coating operations at U.S. Air Force (USAF) depots will lead to significant environmental, occupational, safety, and health benefits, as well as increased productivity. Specifically, the project’s purpose is to develop a reduced solvent-borne rain erosion coating systems saving VOC or HAP emissions by tens of thousands of pounds per year.

Occupational, safety and health benefits will be realized by eliminating worker exposure to isocyanate-containing coatings, and production improvements will result from significantly shorter coating cure times. Rapid-cure coatings can minimize the overall processing time required for paint application, allowing for the immediate assembly or installation of coated components, resulting in significant increases in production rates. Furthermore, reduced cure time also has the potential to eliminate rework required from coating contamination during application and curing.

Some military aircraft and shipboard surfaces, such as radomes, antennas, gun shields, wing leading edges, and helicopter blade leading edges are coated with a specialized erosion-resistant protective coating possessing strict performance requirements such as those specified in SAE AMS-C-83231A. Current specialized protective coatings typically contain up to 800 grams per liter of VOCs and high levels of HAPs such as xylene, toluene and methylisobutylketone (MIBK). These multi-component coatings are cured by chemical reaction, and once mixed, any excess materials must be disposed of as hazardous waste. In addition, many of these coatings contain isocyanates, which are hazardous and may be prohibited for use in the near future under the Prohibited and Controlled Chemical List (PCCL). There are currently no environmentally benign wear resistant coating alternatives that can meet performance requirements.

In addition to the environmental burden posed by these protective coatings, their use presents a significant production burden associated with application and cure times. The relatively thick coating required to ensure adequate performance means that multiple spray passes are made to achieve the final dry film thickness. With the relatively high solvent content of the coatings, a significant flash-off time is required between coating passes. As a result, the current coatings can take up to 12 hours to properly apply and 5 to 7 days to cure completely. Under less than ideal conditions, such as low humidity or temperatures, these cure times can increase significantly. These long cure times contribute to excessive backlogs in production and reduced availability to warfighters.

Thousands of gallons of these specialized coatings are used annually in the maintenance and repair of DoD weapon systems resulting in large cumulative releases of VOCs and HAPs. For example, Ogden Air Logistics Complex processes approximately 96 F-16 radomes a year, Warner Robins Air Logistics Complex reported processing up to 360 F-15 radomes and 240 C-130 radomes per year and Oklahoma City Air Logistics Complex processes approximately 100 KC-135 radomes and 24 B-52 radomes per year. Additionally, U.S. Navy aircraft such as the P-8A have over 100 radomes or antennas on the exterior of the aircraft that require periodic recoating.

The cost and time to meet the requirements of this SON were at the discretion of the proposer. Two options were available.

Standard Proposals: These proposals describe a complete research effort. The proposer should incorporate the appropriate time, schedule, and cost requirements to accomplish the scope of work proposed. SERDP projects normally run from two to five years in length and vary considerably in cost consistent with the scope of the effort. It is expected that most proposals will fall into this category.

Limited Scope Proposals: Proposers with innovative approaches to the SON that entail high technical risk or have minimal supporting data may submit a Limited Scope Proposal for funding up to $150,000 and approximately one year in duration. Such proposals may be eligible for followon funding if they result in a successful initial project. The objective of these proposals should be to acquire the data necessary to demonstrate proof-of-concept or reduction of risk that will lead to development of a future Standard Proposal. Proposers should submit Limited Scope Proposals in accordance with the SERDP Core Solicitation instructions and deadlines.