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PRODUCTS FINISHING — PFonline.com 15 The International Agency for Research on Cancer (IARC) has determined that Cr 6 compounds are carcinogenic to humans, and the National Toxicology Program 11th Report on Carcinogens classifies Cr 6 compounds as known to be human carcinogens. Occupational exposure includes the inhalation of dusts, mists or fumes, and dermal contact with chromium- containing products. In response to the health risk posed by exposure to Cr 6 , occupational and environmental regulations in the U.S. and European Union are becoming increasingly stringent. These regulations make the use of coatings containing Cr 6 increas- ingly more expensive, and increase the risk that a coating used in critical applications could become unavailable. NASA and ESA continue to search for Cr 6 alternatives that meet performance requirements in corrosion protection, cost, operability, health and safety, while specifying that perfor- mance must be equal to or greater than existing systems. The overall objective of the collaborative effort between NASA TEERM and ESA is to test and evaluate coating systems (pretreat- ments, pretreatments with primer, and pretreatments with primer and topcoat) as replacements for Cr 6 coatings in aerospace applications. This objective will be accomplished by testing prom- ising coatings identified from previous NASA, ESA, Department of Defense (DOD), and other project experience. Testing is in progress at KSC CTL and at the ESA ESTEC. Preliminary results from the pretreatment testing at KSC are discussed here. Pretreatment Testing at KSC Test Articles: Table 1 lists the aluminum alloys selected for testing because of their relatively common use in avionics and aerospace applications and/or their ability to exhibit similar performance to other materials of interest. Two of the alloys, 2024-T8 and 7075-T73, were supplied by ESA. All test panels were procured mill finished without mill markings. The pretreatments used are shown in Table 1. Two of the pretreatments, Bonderite M-NT 65000 and MAPSIL SILICo (thin), were supplied by ESA. MAPSIL SILICo (thin) is approximately 3 micrometers (µm) to 5 µm thick when applied to a panel. Testing Approach: Test panels with pretreatment only were evaluated by NASA and ESA under a variety of environmental test conditions. See Table 2 for test methods, evaluation criteria, and the location where testing was conducted. Only results of the salt spray testing conducted at KSC are reported here. Salt Spray Resistance: This test is used to rapidly evaluate the performance of a coating or coating system and how well it prevents corrosion. Salt spray exposure and corrosion resis- tance is a requirement of MIL-DTL-5541. A solid rocket motor for the United Launch Alliance Atlas V rocket slated to boost NASA's Magnetospheric Multiscale mission, or MMS, is lowered into position inside the mobile service tower at Space Launch Complex 41 on Cape Canaveral Air Force Station in Florida. Photo courtesy of NASA. TABLE 1: Alloys and Pretreatments Used in Test Articles PRETREATMENT MANUFACTURER ALLOYS Metalast * TCP HF Metalast * Minden, Nevada 2024-T3, 2024-T8, 6061-T6, 7075-T6, 7075-T73 SurTec 650V SurTec Bensheim, Germany Bonderite M-NT 65000 Henkel Düsseldorf, Germany MAPSIL SILICo (3-5 μm) MAP Pamiers, France * Now Chemeon Surface Technology REPLACING HEXAVALENT CHROMIUM