DESCRIPTION: Aluminum aircraft components that require repair or re-work at NAVAIR's Fleet Readiness Centers (FRCs) are subjected to multiple aqueous immersion tank processing steps for preparation of metallic surfaces prior to application of corrosion protective coatings. These chemical processing tanks require thousands of gallons of hazardous materials to clean, etch, and de-oxidize aluminum alloys prior to application of chemical conversion coating or anodize coating. Each process step requires a water rinse prior to the next step to neutralize the reaction, clean the surface, and prevent drag-out contamination of the subsequent process tank. The rinse water is then contaminated and considered a hazardous material that must be disposed of properly. The large amount of hazardous chemicals and contaminated rinse water generated from the aluminum surface preparation process are cost prohibitive, an environmental risk, and hazardous to human health. These aqueous processes also include process variations that occur due to upstream chemical variation. These chemical variations are a product of processing multiple aluminum alloys in the same aqueous solution that is altered with each production run/batch until the process tank is changed out. Current approach requires significant component processing time, process variation, and hazardous material disposal costs.

This innovative environmentally benign method, process, or technology will replace aqueous hazardous materials without increasing processing time or compromising corrosion protection performance, while reducing hazardous material costs. The innovation should reduce or eliminate traditional hazardous chemicals required for aluminum components processing including mildly alkaline cleaners, acid or alkaline chemical etchant, various deoxidizer and disputer acids, alternative Methyl Ethyl Ketone (MEK) approved organic wipe solvents, biflouride pickling/cleaning, and contaminated rinse water from rinsing in-between each process step. Requirements include that the new method, process, or technology will be compatible with currently used chemical conversion coating material, Ion Vapor Deposition (IVD) Aluminum process, and the three types of anodization.
 

PHASE I: Develop a new aluminum surface preparation process replacing hazardous materials prior to application of chemical conversion coating or anodization as a corrosion protective coating. Demonstrate the feasibility of the new process through bench top surface preparation. Surface preparation will be inspected using portable goniometry instead of the traditional water-break test to gain quantitative water contact angle data for analysis of surface wettability. The surface adhesion of the protective coating to the aluminum alloy must pass a Dry and Wet Tape Adhesion Test, and have acceptable performance in Salt Fog Corrosion Resistance Testing.
 

PHASE II: Fully develop an aluminum surface preparation process that can be operated manually or automatically on aircraft components without a significant increase in processing time or costs when compared to the current immersion tank surface preparation process. Operational parameters will be optimized with aluminum coupon testing and analysis. Testing and analysis in this phase will include metallurgical, mechanical, corrosion resistance, and surface characterization of the new surface preparation process on various commonly used aircraft aluminum alloys (i.e., 2024, 7050, and 7075 alloys). Process development and evaluation will also include using scrapped components to demonstrate and validate (DEM/VAL) the new aluminum surface preparation process to establish and refine practical applications as an alternative to the immersion tank based surface preparation process currently used.
 

PHASE III DUAL USE APPLICATIONS: Perform full scale corrosion resistance testing of new aluminum surface preparation process on a selected aircraft component. Transition and implement the developed surface preparation process for Navy use as an alternative to the current aqueous immersion tank surface preparation process. The small business will work with the Navy, DoD, and industry to transition through the appropriate qualification process.  Commercial transportation industries including: shipping, aerospace, and automotive would benefit significantly from an environmentally benign aluminum surface preparation process for application of corrosion resistant coatings because a high percentage of transportation components are made of aluminum or are going to be made out of aluminum because of the abundance of the material, its strength to weight ratio, and its relative corrosion resistance.
 

REFERENCES:

1. ASTM D3359 Measuring Adhesion by Tape Test. Retrieved from http://everyspec.com/
 

2. NAVAIR 01-1A-509 Aircraft Cleaning and Corrosion Control Manual. Retrieved from http://everyspec.com/
 

3. MIL-PRF-23377 Solvent-borne, Epoxy primer. Retrieved from http://everyspec.com/
 

4. MIL-PRF-85582 Water-borne, Epoxy primer. Retrieved from http://everyspec.com/
 

5. MIL-PRF-85285 Polyurethane Paint Coating. Retrieved from http://everyspec.com/
 

6. MIL-DTL-81706 Aluminum Chemical Conversion Coating. Retrieved from http://everyspec.com/
 

7. AMS-M-3171 Magnesium Chemical Conversion Coating. Retrieved from http://everyspec.com/
 

8. ASTM B117 Salt Spray/Fog Test. Retrieved from http://everyspec.com/