Published: Jan 1997
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The ignition resistance of hard (type III) anodized aluminum alloy to particle impact in pure oxygen was investigated. Test samples with aluminum oxide film thicknesses of 3 μm (0.12 mils), 5 μm (0.20 mils), 20 μm (0.79 mils), and 50 μm (1.97 mils) were tested at six different temperatures ranging from 239 K (-28 °F) to 672 K (750 °F). These anodized test samples were placed in a supersonic particle impact chamber with the impact surfaces directly exposed to the impacting particles. Aluminum alloy particles of 2000 μm (0.078 in.) diameter were used to promote ignition upon impact. The event of ignition was recorded on standard video. The test results are plotted as Logistic Regression curves showing the ignition frequency over the temperature range tested. The results are compared to previously tested soft anodized (type II) aluminum alloy and bare aluminum alloy. The results indicate that the hard (type III) anodized coating offers increased resistance to particle impact ignition as compared to bare aluminum. The data is inconclusive as to which anodization process (type II or type III) provides better protection from ignition.
particle impact, oxygen, flammability, fire, materials, ignition resistance, ignition mechanism, anodized aluminum, alloy
Mechanical Engineer, AlliedSignal Technical Services Corp. Team, NASA Johnson Space Center White Sands Test Facility, Las Cruces, NM
Mechanical Engineer, NASA Laboratories Office, NASA Johnson Space Center White Sands Test Facility, Las Cruces, NM