Replacement of Toxic Materials in US Aerospace and Defense
We will discuss what US Aerospace and Defense (A&D) organizations are doing to replace Cd, chromates, etc, and the developments that are taking place to reduce the time and cost of doing so.
In response to North American and European regulations and ESOH concerns, the US Department of Defense and the A&D supply chain are replacing materials, treatments and coatings that are themselves toxic or require the use of toxic chemicals for manufacturing or sustainment. For example, chromated Cd is being replaced throughout the A&D industry by ZnNi with Cr3 passivate, and hexavalent chromium-containing organic and inorganic coatings are being replaced with numerous alternatives. With increasing pressure on Cr3 as it replaces Cr6 we are also moving towards non-chrome (NC) materials.
What we are finding, however, is that the old Edison approach of formulate/test/re-formulate/re-test is far too uncertain, slow and expensive, especially for the replacement of corrosion-control materials such as chromated passivates and primers. We are therefore creating new materials-development approaches based on computational methods for modeling, predicting and testing the performance of organic and inorganic systems. These new approaches are beginning to incorporate corrosion and stress environments, corrosion environment fluid dynamics, and paint system degradation. At the same time we are developing better corrosion test methods that more accurately predict actual service performance. All of this is aimed at short-circuiting the very long and expensive process of cabinet testing/atmospheric testing/service testing, with its multiple formulations and adjustments that are required to develop new non-toxic materials and coatings.