CVD Coatings For Space Exploration Applications

 

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                   Application

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                 Benefit

Prevent Iodine Reactivity       

Minimize Sample Loss

Improved Heat Transfer 

High Durability Inertness

 
 Get the latest data and learn about SilcoTek® coating applications for your industry!  Watch our anti-fouling webinar.

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Thrusters

Hall-effect thrusters have been used in space exploration applications such as satellites and medium-sized robotic space vehicles since the 1970s. These engines work by ionizing a propellant and accelerating these ions with an electrostatic potential to produce thrust. Xenon gas is the most commonly used propellant due to its high atomic weight (easy to ionize) and its chemical inertness; however, storage requires low temperatures and high pressures.

NASA Glenn Research Center has demonstrated that Hall-effect thrusters operating with iodine as the propellant can perform at the same thrust and efficiency compared to state-of-the-art xenon thrusters. Iodine has many logistical benefits over xenon for use in these engines. Iodine stores at 3 times the density of xenon, it can be stored at less than 15 psi, whereas xenon requires 2500 psi, and iodine is much more abundant than xenon, and therefore cheaper.

The Challenge

Despite these benefits, there are challenges to consider with material compatibility. Because iodine is a halogen, it can react with and oxidize surfaces, causing damage to process systems and in NASA's case may react with iodine Hall-effect thruster propulsion system materials.  Very little is known regarding iodine reactivity with the wide range of spacecraft materials used in a vacuum environment. This information would also be useful to the nuclear industry as iodine is regarded as one of the most hazardous fission products from a fuel nuclear reactor. NASA has developed an experiment to study the interaction between iodine and a variety of common spacecraft materials. In their tests, they have included protective coatings like corrosion resistant Silcolloy® and high durability Dursan® coated coupons for evaluation.

Read The Summary  Of The NASA Study

NASA stated the evaluation objective:

“The goal of this work is to begin studying the chemistry, structure and micro structural, and kinetic properties of materials and coatings exposed to iodine in a relevant environment to spacecraft technology development. For the study described in this report, five common spacecraft and test facility metals and two coatings were selected. The results of this work are pertinent to vacuum facilities and some regions of space since these environments contain molecular or atomic oxygen at very low levels.”

This report investigated iodine exposure to 304 and 316 stainless steel, A36 low carbon steel, 6061 aluminum, and 6Al-4V TiAl alloy. The study also includes Silcolloy coated on every alloy except for the 6061 aluminum, and Dursan only on a 304 stainless steel substrate.

The Results

The iodine exposure test was conducted in a tubular furnace that was held at 300°C and flushed with 145 ml/min of argon gas along with 1 mg/min of iodine vapor. The testing exposed the coupons in triplicate for 5, 15, and 30 days. The coupons were monitored via weight measurements, XRD, and SEM. Weight change can be broken into three distinct groups: the steels which gained weight, the aluminum alloys which lost weight, and the coated coupons that had no weight loss or gain except for Silcolloy on 304 stainless steel which gained weight past the 15-day measurement period (Figure below).  (Read a summary of the study.)

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The authors concluded that Silcolloy® and Dursan® were effective in protecting the coupons that were studied. 

Read the Complete NASA Whitepaper

Want to lean more about SilcoTek® non reactive, corrosion resistant coatings?  Read our E-Book, or watch our technology videos.

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Mass Spectrometry In Space Exploration

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Image credit: NASA/JPL-Caltech

Why are SilcoTek® coatings used in the MS sampling systems like those used on the Cassini probe?  Because no other coating has both the inertness and durability to withstand the harsh environment of space and assure samples taken don't react with the instrument flow path.  SilcoTek coatings like Dursan® beat other industry deactivation technologies and inert surfaces.  The chart below compares the breakdown/loss rate of various deactivations.  The Dursan coating minimized sample breakdown, improving MS sampling results while offering a high temperature stable, high durability surface.  Get our ultimate guide to inert sampling and learn more about how SilcoTek coatings improve sampling performance.

 

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Download Inert Coating Webinar

Coating benefits include:

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  • High temperature stability
  • Low temperature stability
  • Shock resistant and flexible.  Won't delaminate
  • High purity and inert
  • Corrosion resistant
  • High tolerance

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Heat Exchanger Fouling

SilcoTek coatings act as an inert barrier, preventing catalytic or chemical interaction with the underlying surface.  For example nickel containing substrates catalytically form carbon deposits (coke) from petrochemical media. Causing build-up on the surface.  Coatings like SilcoKlean® or Dursan® bond to the surface and change the surface energy and inertness, preventing chemical adhesion and adsorption of the substrate.  The coating's low energy surface prevents the attachment of flow path chemicals to the surface.

SilcoTek Solutions & Applications    
     
Problem SilcoTek Coating Solution  

Carbon deposit, coke, formation from incomplete burning of fuel

SilcoKlean barrier coating reduces catalytic coking and carbon deposit formation

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Bio-fouling in food applications.  Spores from sour milk suspensions stick to testing equipment

Dursan prevents sticking by up to 76%

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Protein binding in medical diagnostics

Dursan prevents surface interaction and sticking

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In Situ Analysis

Rosetta_s_Philae_lander_on_comet_nucleus_node_full_image_2The European Space Agency successfully completed a 6.4 billion kilometer space flight and landed their Rosetta Philae craft on the surface of comet 67P/Churyumov-Gerasimenko for in situ analysis of the comet.  In order to precisely measure the comet's chemical composition, ESA needed an inert surface capable of withstanding the hostile environment of space.  They chose SilcoNert® 1000 (Silcosteel®) for the job! 

 

Robert Sternberg, leader of the space gas chromatography team at Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA) of the University of Paris XII noted:

 

” I would like to mention that all the columns selected for space mission are Silcosteel®-treated metallic capillary columns, and they have all been submitted successfully to space qualification tests such as vibration, radiation, and thermal cycles1, which demonstrated their robustness for space application."

 

 

Get Our Sampling Presentation

SilcoTek® customer Restek Corporation developed space capable chromatography columns featuring SilcoTek coatings.  Our coatings offer unparalleled inertness and durability, allowing the development of inert chromatography columns for space sampling.  Philae deployed 10 instruments to the comet surface, SilcoTek® coatings assured precise measurement of compounds even in the most challenging environments.  LISA went on to note: 

 

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"LISA is very grateful to Restek for being this ideal partner without the help of which the study and development of chromatographic columns for space use could not have been possible"

 


Coat the entire sample pathway, in space or on earth.

To assure accurate sample response and a robust sample surface, coat all sample components, even instrument components! 

Assorted-Sulfinert-Sampling-Parts Liners
Probes
GC column tubing
Weldments
Jets

Regulators
Tubing 
Fittings
Valves
Fritted filters

 

Explore-Full-Newsletter

Follow the accomplishments of the Rosetta craft on Twitter at @ESA_Rosetta or visit their website at http://blogs.esa.int/rosetta/

  • 1C. Szopa, U.J. Meierhenrich, D. Coscia, L. Janin, F. Goesmann, R. Sternberg, J.-F. Brun, G. Israel, M. Cabane, R. Roll, F. Raulin, W. Thiemann and C. Vidal-Madjar and H. Rosenbauer J. Chromatogr. A, 982 303-312 (2002)
  • *Photos courtesy of ESA; copyright ESA.

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Learn more from industry leaders about how SilcoTek® coatings solve material problems and improve performance.

Technical Presentation: Coating Technology 

Coating Data Sheet:  Dursan® Data Sheet

Whitepaper: Reliable Sampling In Challenging Environments 

Whitepaper: Iondine Vapor Exposure NASA Paper