Corrosion Test Seals
2
Corrosion Inhibition of Sealants In An Aggressive Environment METSS 300 Westdale Avenue Westerville, OH 43082 Contact: Dr. Kenneth J. Heater Phone: (614) 797-2200 Fax: (614) 797-2201 Email: [email protected] Website: www.metss.com Contract Number: N68335-05-C-0181 PROBLEM STATEMENT Sealants applied between adjacent panels on aircraft are expected to last the life of the plane despite exposure to harsh environmental conditions, such as salt water and salt saturated air. The sealants are applied to protect the underlying substrate from corrosion caused by the environment. The primary problem is that the sealants themselves, primarily polysulfides, do not survive the harsh environmental conditions to which they are exposed, thus the underlying substrate is subject to attack. Due to increasingly stringent environmental regulations the use of hexavalent chromium is no longer a viable option for inhibiting corrosion. Consequently, new means of stabilizing the sealants and providing corrosion protection are required. TECHNOLOGY DESCRIPTION This program demonstrated that polysulfide sealants are degraded by oxidation, a process that reduced the sealants adhesive strength to an aluminum substrate and made the sealant material more porous, more brittle, and less durable. As a result of the oxidation process the aged sealants ability to protect the underlying METSS Page 1 of 2 Oxidative degradation of
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Transcript of Corrosion Test Seals
Corrosion Inhibition of Sealants In An Aggressive Environment
METSS300 Westdale AvenueWesterville, OH 43082
Contact: Dr. Kenneth J. HeaterPhone: (614) 797-2200 Fax: (614) 797-2201Email: [email protected]: www.metss.com
Contract Number: N68335-05-C-0181
PROBLEM STATEMENT
Sealants applied between adjacent panels on aircraft are expected to last the life of the plane despite exposure to harsh environmental conditions, such as salt water and salt saturated air. The sealants are applied to protect the underlying substrate from corrosion caused by the environment. The primary problem is that the sealants themselves, primarily polysulfides, do not survive the harsh environmental conditions to which they are exposed, thus the underlying substrate is subject to attack. Due to increasingly stringent environmental regulations the use of hexavalent chromium is no longer a viable option for inhibiting corrosion. Consequently, new means of stabilizing the sealants and providing corrosion protection are required.
TECHNOLOGY DESCRIPTION
This program demonstrated that polysulfide sealants are degraded by oxidation, a process that reduced the sealants adhesive strength to an aluminum substrate and made the sealant material more porous, more brittle, and less durable. As a result of the oxidation process the aged sealants ability to protect the underlying substrate from corrosion was reduced. METSS showed that the relative rate of oxidation could be predicted by using the Oxidation Induction Time test. In addition to identifying the process by which polysulfide sealants degrade, METSS was able to identify means for significantly delaying the onset of degradation. The following figure shows that aluminum can be protected from corrosion by a polysulfide sealant after 168 hrs in a salt fog at 95ºF.
METSS Page 1 of 2
Oxidative degradation of polysulfide sealants
TECHNOLOGY AVAILABILITY
This technology is available for potential users in its current state of development. This can be obtained through METSS. The basic science and engineering principles that provide for the prevention of corrosion has been applied to other sealant and seal systems with success. METSS has found that the protective chemistry is often unique the chemistry of the seal/sealant compound. METSS has the ability to work with interested customers to adapt the technology to any of these product forms for use in any environment.
METSS Page 2 of 2
sealant
Sealant removed
Unprotected aluminum
