2006-2007 - Kennedy Space Center Technology Transfer Office

More documents

Recommendations

Info

Photocatalytic Coatings for Exploration and Spaceport Design2006 Center Director’s Discretionary Fund ProjectCorrosionControlThis project developed self-cleaning photocatalytic coatings that remove contaminationwithout human intervention. The coatings chemically remove organic contaminants and leaveno residue. The photocatalyst will not negatively affect other coating properties, especiallycorrosion resistance.Titanium dioxide, TiO 2, is an extremely popular photocatalyst because of its chemical stability,nontoxicity, and low cost. TiO 2is commonly used in the photocatalytic oxidation of organic matteror pollutants in the gas and liquid phases. However, TiO 2does have some drawbacks. It has limitedlight absorption because of its large band-gap and suffers from a photonic efficiency of less than10 percent for organic degradation. Dopants can lower the band-gap and improve efficiency. Sincethe photocatalytically active form of TiO 2is a nanocrystalline powder, it can be difficult to make arobust coating with enough catalyst loading to be effective.Photocatalysts become active when certain light energy is absorbed. When photons with an energygreater than the band-gap, E g, (wavelengths shorter than 400 nm) impinge upon the surface of theTiO 2, an electron-hole pair is formed (Figure 1). The electron-hole pair oxidizes adsorbed substanceseither directly or via reactive intermediates that form on the surface, such as hydroxyl radicals (OH·)or superoxide ions (O 2–).Several factors can influence the band-gap energy of TiO 2, two of which are crystal structure andimpurities. TiO 2exists as three crystal structures—brookite, anatase, and rutile—that can becontrolled via heat treatment. Anatase is the most photocatalytically active crystal form of TiO 2.Doping TiO 2with impurities can alter its band-gap energy, as well as its effectiveness as a catalyst.Depending on their size, dopant atoms can occupy either the substitutional or interstitial latticepositions. Atoms that are relatively large will assume the interstitial positions and create a muchgreater energy disturbance in the crystal than will smaller atoms that take on the substitutionalpositions. This energy disturbance narrows the band-gap and thus allows photons with longerwavelengths and smaller energies (such as those in the visible-light spectrum) to create electron-holepairs.Raman spectroscopy was performed for the purpose of determining the crystal structure and thedegree of crystallinity of the TiO 2particles. Reflectance measurements indicated the wavelengthsof light absorbed by the different catalysts. Reflectance is inversely proportional to absorbance andcan help approximate the band-gap. The wavelength where the percentage of reflectance beginsto decrease approximates the band-gap. For pure TiO 2, only the sample heated to 600 °C exhibitsdifferent spectral behavior from the others. Its rutile crystal structure ended its absorbance near awavelength of 460 nm instead of the 435-nm wavelength characteristic of the other samples in theanatase phase.For the catalysis evaluation, 20 µL of 0.2-mg/mL Rhodamine B dye in ethanol was added to10-mg samples of the catalyst. Half of the prepared samples were exposed to ultraviolet (UV)radiation (from an F8T5/BLB fluorescent light with peak emission at 365 nm) for 24 hours, whilethe other half were kept in the dark. Upon completion of the UV test, the addition of 5 mL of waterdissolved the remaining dye. The absorbance of the dye, measured with an HP spectrophotometer,between 450 nm and 615 nm, revealed the amount of dye remaining after exposure. The effectivenessof each catalyst was determined by the comparison of the amount of absorbance of the dye remainingin the samples with the initial absorbance of the dye alone. All measurements were made in triplicate.Figure 2 shows results for the cleaning efficiency of pure TiO 2made with three different proceduresand different heat treatments. Procedure 3 with a heat treatment at 400 °C performed the best. Ingeneral for all the doped catalysts, Procedure 3 with the same heat treatment performed the best.14 Spaceport Structures and Materials
Contacts: Dr. Paul E. Hintze , NASA-KSC, (321) 867-3751; andDr. Luz Marina Calle , NASA-KSC, (321) 867-3278Participating Organizations: NASA-KSC (Amanda B. Napier) and ASRC Aerospace (Jerome P. Curran)e –Conduction BandE ghνValence Bandh +Figure 1. Electronic band structure of a semiconductor showingthe electron-hole pair formed after it absorbs a photon of light.100Procedure 1 Procedure 2 Procedure 3908070Dye Removal (%)6050403020100NHT 200 400 600Heat Treatment (°C)Figure 2. Dye reduction after the catalyst was exposed to UV light for 24hours. The catalyst was pure TiO 2made in three ways with different heattreatments. The high percentage reduction indicates that the catalystoxidized nearly all the dye in contact with the surface. NHT indicates noheat treatment.KSC Technology Development and Application 2006-200715
Page 5 and 6: ForewordSuccessful technology devel
Page 7 and 8: ContentsSpaceport Structures and Ma
Page 9 and 10: Contents (continued)Process and Hum
Page 11 and 12: IntroductionJohn F. Kennedy Space C
Page 13 and 14: Constellation SystemsSurfaceSystems
Page 15 and 16: Spaceport Structures and MaterialsK
Page 17 and 18: 20181614∆ E1210Modified Sensor Be
Page 19 and 20: Initial results of the EDEM model o
Page 21 and 22: Contacts: Dr. Carlos I. Calle ,NASA
Page 23 and 24: Close examination of the corrosions
Page 25 and 26: Adhesion at Failure (psi)2500200015
Page 27: Figure 1. After 500 hours of salt f
Page 31 and 32: Figure 2. Repairs to various types
Page 33 and 34: on top of the cuvette contains the
Page 35 and 36: Figure 2. A corrugated NiTi sheet e
Page 37 and 38: The PLTD can be used to (1) calibra
Page 39 and 40: SEM images of neat MWNT fibers: (a)
Page 41 and 42: Contacts: Trent M. Smith
Page 43 and 44: Figure 1. An isometric cutaway view
Page 45 and 46: Figure 2. Quartz sand flowing in th
Page 47 and 48: Figure 2. Top images show how the e
Page 49 and 50: Sand volume fraction contour at t =
Page 51 and 52: Integrated LWRD/RVC engineering bre
Page 53 and 54: Mean relative percentage change in
Page 55 and 56: We compared the model’s predictio
Page 57 and 58: Figure 2. Three-dimensional simulat
Page 59 and 60: Figure 3. Camera calibration model.
Page 61 and 62: The sketch in Figure 2 shows alaunc
Page 63: Figure 2. Signal generator (right)
Page 66 and 67: Hail Size Distribution MappingA 3-D
Page 68 and 69: Launch Pad 39 Hail Monitor Array Sy
Page 70 and 71: Autonomous Flight Safety System - P
Page 72 and 73: The Photogrammetry CubeSpaceport/Ra
Page 74 and 75: Bird Vision SystemThe Bird Vision s
Page 76 and 77: Automating Range Surveillance Throu
Page 78 and 79:
Next-Generation Telemetry Workstati
Page 80 and 81:
GPS Metric Tracking UnitAs Global P
Page 82 and 83:
Space-Based RangeSpace-Based Range
Page 85 and 86:
Fluid System TechnologiesKSC Techno
Page 87 and 88:
0.900.850.80Discharge Coefficient,
Page 89 and 90:
Composite seals for performance eva
Page 91 and 92:
140000120000100000Signal80000600004
Page 93 and 94:
Contacts: Dr. Barry J. Meneghelli ,
Page 95 and 96:
60555045Comparative k-value (mW/m-K
Page 97 and 98:
a compatible spacecraft model where
Page 99 and 100:
In an ongoing effort for improvemen
Page 101:
Low-gravity probe prototype test.th
Page 104 and 105:
Countermeasure for Radiation Protec
Page 106 and 107:
Focused Metabolite Profiling for Di
Page 109 and 110:
Process and Human FactorsEngineerin
Page 111 and 112:
DON uses game technology to enable
Page 113 and 114:
Type of mobile crane that impacted
Page 115 and 116:
SALT proof-of-concept communication
Page 117 and 118:
SSLM CAD model.Our design offers th
Page 119 and 120:
Variables that can be integrated by
Page 121:
Exploration Supply Chain Simulation
Page 124 and 125:
Nanosensors for Evaluating Hazardou
Page 126 and 127:
Sixty-four-Channel Inline Cable Tes
Page 128 and 129:
Wireless Inclinometer Calibration S
Page 130 and 131:
Generating Safety-Critical PLC Code
Page 132 and 133:
Spacecraft Electrostatic Radiation
Page 134 and 135:
Ion Beam Propulsion StudySpacecraft
Page 136 and 137:
RT-MATRIX: Measuring Total Organic
Page 139 and 140:
Appendix AKSC High-Priority Technol
Page 141 and 142:
Risk Assessment ToolMission Data Fe
Page 143 and 144:
Appendix BInnovative Partnership Pr
Page 145 and 146:
system for the Government, using th
Page 147:
tracking objects after launch, and
show all

2006-2007 - Kennedy Space Center Technology Transfer Office

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?