Binary Colloidal Alloy Test - C1 (BCAT-C1) - 03.25.14
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The Binary Colloidal Alloy Test-C1 (BCAT-C1) experiment studies nano-scale particles dispersed in liquid, known as a colloidal suspension, commonly found in such commercial commodities as paint, electronic polishing compounds and food products. These suspensions have the unique property that the particles phase separate (like oil and water) and the particles self-assemble into crystals that interact strongly with light (like opal). Photographing these samples in microgravity allows the measurement of these processes while avoiding the effects of particle sinking due to gravity. This study allows the development of new insights into this important material process.
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ZIN Technologies Incorporated, Cleveland, OH, United States
Canadian Space Agency (CSA), Saint-Hubert, Quebec, Canada
Sponsoring Space Agency
Canadian Space Agency (CSA)
ISS Expedition Duration
May 2012 - October 2015
Previous ISS Missions
The BCAT series of investigations began on ISS Expedition 8.
Colloidal suspensions are used in innumerable applications ranging from the polishing of silicon wafers in the electronics industry to the filtering of fruit juices in the food industry. Scientifically, colloidal suspensions serve as models of molecular systems for the study of inter-particle interactions and phase (i.e. gas/liquid/solid) transitions because the interactions between the suspended particles can be varied with relative ease. Depending upon the sample preparation conditions, the suspended particles form gas, liquid and crystal phases. Transitions between gas and liquid are characterized by growth of domains of one phase within the other. Formation of crystals from a well-mixed sample involves the growth of crystallites within the sample. Each of these phenomena has been studied, but simultaneous crystallization and phase separation remains largely uncharacterized.
In the experiment led by SFU, researchers plan to study samples consisting of colloidal suspensions with added polymer that, in equilibrium, contain more than one phase so that the effect of phase separation on crystal growth can be studied. On Earth, gravity causes the colloids to settle making such a study particularly difficult. In samples prepared by NYU, seed particles have been added to colloid samples which crystallize and the objective is to determine the impact on crystallization speed in the absence of gravity.
Performing these experiments in the microgravity environment of the International Space Station allows the study of the growth of much larger structures, and, thus, maximizes the extent to which the behaviour can be explored. Improved understanding of these processes may lead to more refined manufacturing processes and commercial products.
The focus of the SFU investigation is specifically on the effect of phase separation on crystal growth. On Earth, gravity causes the colloids to settle, making such a study particularly difficult. Performing these experiments in the microgravity environment of the International Space Station allows scientists to study growth of much larger structures, and, thus, maximize the extent to which the behavior can be explored. Improved understanding of these processes may lead to more refined manufacturing processes and commercial products. The competition between a phase separation process and an order-disorder transition remains largely unstudied and offers an opportunity to observe some fascinating behavior. The overarching goal of all these experiments is to develop the key knowledge to help make colloidal engineering a reality. In addition, this experiment should help scientists understand some of the fundamental properties of colloid-polymer mixtures to further improve the commercial use of such systems. The purpose of the NYU investigation is to study the effect of spherical seeds on colloidal particle nucleation. One sample will contain no seed particles and act as a control. The other two will contain minute amounts, < 0.1% of different sizes of seed particles. Investigators hope to measure variations in crystallization speed.
No space application has been identified yet
Outcomes of the BCAT-C1 study will be applicable to industrial processes involving colloids in the future, which could include finding new ways to produce plastics or extend the shelf-life of consumer products.
BCAT-C1 samples are contained within a small case the size of a school textbook. The experiment requires a crew member to set up on the Maintenance Work Area (MWA) or on a handrail/seat track configuration, set up camera and start the automatic photography of each sample at close range using the onboard Kodak DCS760 camera. All samples also require that manual photographs using the EarthKAM software (at least initially) be taken by an astronaut. The pictures are down-linked to investigators on the ground for analysis.
1. Crew sets up the historical Video camera to document the BCAT-C1 operations as performed on-board the ISS.
2. Crew sets up all hardware on MWA of seat track rails (Slow Growth Sample Module, D2Xs Camera, flash and EarthKAM software with SSC Laptop).
3. Crew homogenizes (mixes) the sample(s) and takes the first photographs manually. This helps them optimize the setup and shows that the samples were initially fully homogenized when publishing results later.
4. Camera is set to take automatic photographs every 10 min for 8h, then every hour for 5 days (SFU samples) or every 4h for the first 10 days (NYU samples).
5. Photograph interval is changed for every 2h (SFU) or 8h (NYU) for the remaining of the run.
6. At the completion of the run, a crew member tears down and stows all hardware (30 minutes), except if another run is planned.
7. Photos are down-linked to the science team.
BCAT-C1Colloidal Science on the International Space Station
NIH BioMed-ISS Meeting Video Presentation, 2009?BCAT-C1
NIH BioMed-ISS Meeting, 2009?BCAT-C1
NASA Image: ISS016E027863 - Astronaut Dan Tani took this photograph of the BCAT-3 Sample Module using his own design for a ceiling mount in Node 2 of the International Space Station. Great high contrast pictures of difficult to capture images resulted from using this setup (February 2008).
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NASA Image: ISS032E022445 Image of BCAT-C1.
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NASA Image: ISS032E022512 - BCAT-C1.
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