Development of Corrosion Test to Predict or Rank Corrosion Performance of Current and Novel Corrosion Inhibiting Sealants, Both Conductive and Non-Con

The Navy has observed that the primary factor associated with good initial corrosion resistance, as determined by salt spray tests, is the level of adhesion between the sealant and metal substrate. Unfortunately, neither adhesion nor salt spray testing can be used to predict service life, or to determine the performance of a sealant formulation beyond the initial qualifying tests. METSS will address this need under the proposed program by developing an analytical test to predict and rank the corrosion protection capabilities of sealants used in aggressive environments. The proposed test method will be applicable to both conductive and nonconductive sealants, and is not specific to sealant chemistry. The test METSS proposes will examine the pertinent chemical changes within the sealant formulation that lead to loss of adhesion and the establishment of conditions necessary to initiate corrosion. As such, this test can compare different sealant formulations, different corrosion inhibiting additives, and can eventually be used to predict service life once correlating data are developed. While this proposal is directed toward polysulfide sealants, subsequent development will permit the comparison of sealants based on different polymers. The proposed test is based on the onset of chemical changes within the sealant that lead to loss of adhesion at the sealant/metal interface due to corrosion induced or auto oxidation processes.