The objectives of this project are to:

• Develop a coating prognostic model for rapid transition by leveraging existing coating and corrosion performance measurements, combined effects testing, and Air Force Condition Based Maintenance Plus (CBM+) projects;
• Verify the model predictions for coating damage and inhibitor exhaustion in laboratory tests, outdoor exposures, and with observations of Department of Defense (DoD) assets focusing on aircraft;
• Establish a protocol for coating testing to extend the model to other assets and material systems; and
• Complete a predictive coating condition model (PCCM) module for direct integration with Air Force CBM+.

If successful, the PCCM will enable CBM+ for a broad range of DoD assets. It could be used to manage corrosion protection systems, which should minimize overall frequency of repaint and structural repairs thus reducing hazardous air pollutants (HAPs), volatile organic compounds (VOCs), and waste generation, as well as minimize worker exposure to hazardous materials, reduce costs, and increase asset availability.

To achieve a practical tool, a stochastic survival model will be developed to cope with the complex physics, material combinations, and dynamic environmental conditions required to predict coating cracking and inhibitor exhaustion. Statistical machine learning approaches for event prediction include both fixed and time dependent covariates, and mixture of models applied to clusters with similar features such as coating type, operation, and environmental conditions. The intent is to achieve the simplest possible model that uses easily accessible data to provide maintainers with insight as to the degradation of a specific asset. The tasks have been developed to accomplish the goals of the project by leveraging Strategic Environmental Research and Development Program (SERDP), Small Business Innovative Research (SBIR), government funded programs, and internal research and development.

First, the assets, structures, and materials for PCCM development will be determined. Conditions and damage modes will be detailed to establish the scope of testing for model development. Laboratory tests will quantify inhibitor exhaustion processes using real time measurements of environment and degradation processes to support model design and development. Factors affecting coating cracking will then be investigated. The combined effects of environmental and mechanical processes on coating cracking and inhibitor exhaustion will be studied using laboratory methods and outdoor exposure sites from related previous and existing projects. Coupled cracking and inhibitor model development will be performed by leveraging data from the previous steps and data from parallel funded efforts. Finally, plans for implementation of the PCCM as a CBM+ module for subsequent Air Force demonstration will be detailed.

This effort seeks to bridge the knowledge gap that exists in the area of coating integrity. An understanding of a coating’s remaining useful life and the current amount of protection it provides on a given substrate is paramount to minimizing hazardous waste by reducing coating applications that are not warranted. As such, the time when coating maintenance activities take place will be optimized, saving taxpayer funds and prolonging the life of aging DoD assets. Additionally, this will increase mission readiness and safety by performing more cost effective, preventative maintenance actions prior to needing more costly corrective maintenance actions due to corrosion.