IntroductionKSC’s Analytical Laboratories branch provides Center-wide chemical analysis support for the identification ofcontaminants found in payloads, flight hardware, cleanrooms, and processing facilities for programs such asOrion, and almost every payload launched from KSCincluding commercial operations. This is a common butvery serious issue and there are stringent health andsafety restrictions pertaining to foreign object debrisand contamination in aerospace systems due to theirextremely sensitive nature and potential to interfacewith the astronauts aboard the ISS. Whencontamination is discovered, such as fibers, particles,residues, etc., it is sampled and then analyzed todetermine its identity. Fourier Transform Infraredspectroscopy (FTIR) is a critical component of thisanalysis.

AcknowledgementsReferencesHoward, P. M. Training. NASA Kennedy Space Center.Mullen, M. (2016). Pathways intern report. John F. Kennedy Space Center, NASA.

Sample AnalysisEvery year we receive hundreds of samples, all from different customers, facilities, projects, and systems. Samples range fromsimple greases and particulates to very complex mixtures of a number of different contaminants. The key to faster and moreconfident interpretation is to build your own internal database of spectra. This summer I conducted a number of differentanalyses, one being of aerospace greases, to familiarize myself with common greases, oils, and hydraulic fluids used indifferent flight and ground systems.

Fourier Transform Infrared Spectroscopy

Unknown Aerospace Contaminant Analysis

Macy Mullen, NE-L3 Purdue University Chemistry Mentor: Philip Howard

Background:

How does it work and what does

it tell us?

1. A beam of infrared radiation is passed through asample.

Spectral Interpretation: The Basics

2. The IR beam excites the chemical bonds in themolecules of the sample causing them to vibrate.

sample

3. These vibrations absorb the infrared radiation atdifferent wavelengths. Each molecule and materialcreates a unique absorption spectrum that indicateswhat sort of bonds, and therefore structure, it has.

These spectra indicate what sort of functional groups amaterial consists of. With that being known, scientistscan use that data to extrapolate the structure andproperties of unknown samples or newly synthesizedcompounds.

http://www.rsc.org

An IR spectrum displays the frequencies, measured in wavenumbers (ṽ= Τ1 λ = cm−1), that are being absorbed by thechemical bonds of a material. The percent absorbance, height of the peaks, follows the Beer’s law (see Figure 1). Whatmakes FTIR so advantageous is the wide range of materials capable of being analyzed using this technique, see below:

http://www.compoundchem.com

• Hydrocarbons- Aliphatic- Unsaturated- Aromatic

• Amines- Primary- Secondary

• Nitriles• Alkyl Halides• Ethers• Alcohols• Carbonyls

- Ketones- Aldehydes- Esters- Amides- Carboxylic Acids

• Inorganics

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𝐼0 = light intensity initial𝐼 = light intensity final𝜀 = sample molar absorptivityl = sample path lengthc = sample concentration

Figure 1. Beer’s Law equation

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Halocarbon®25-10M is polychlorotrifluoroethylene (PCTFE).This grease is commonly found in oxygen systems, from theApollo ground systems to the ISS. The halogenated nature (Cland F) of this grease makes it compatible with systemshandling oxidizers, unlike hydrocarbon greases.

1

Krytox®240AC is acommon aerospace lubricant used in numerous vehiclesincluding the space shuttle. It is a perfluoropolyether (PFPE)based grease thickened with polytetrafluoroethylene (PTFE)capable of withstanding extreme conditions, is chemicallyinert, and one of the original greases to meet militaryspecifications for fuel and oxidizer resistance.

2

Brayco®815Z is a PFPE base oil for Braycote® 600EF and602EF. It is compatible with aerospace fuels and ,due to itschemical inertness, is unaltered by UV and cosmicradiation, high vacuums, and low temperatures. One ofthe more famous places it can be found is the gearboxeson the Mars Curiosity rover.

Braycote®600EF is Brayco®815Z thickened withpolytetrafluoroethylene (PTFE). This grease acts as both alubricant and corrosion inhibitor for the ISS.

This synthetic diester hydraulic fluid is found all overcenter in a variety of different programs, such as the DeltaII launch vehicle. Even though this vehicle is now retired,knowing which facilities house certain materials helps todetermine whether a contaminant is entirely foreign ormigrated from somewhere else on the system.

3

4

Braycote®602EF isBraycote®600EF withmolybdenum disulfide(MoS2). This additive isindicative of extremepressure environmentswhere if the base oil

were squeezed out of the system, the MoS2 particles wouldact as a dry lubricant.

5

1 2 3 4 5 6

6

My sincere gratitude goes to Phil Howard for taking the time to not only teach his interns how to use instruments and standardanalysis processes, but also the methods and techniques that have made him so successful.

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https://ntrs.nasa.gov/search.jsp?R=20190030915 2020-03-24T16:06:57+00:00Z