Browsing by Author "Buhrow, Jerry"
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Item Biofilm Resistant Coatings for Space Applications(48th International Conference on Environmental Systems, 2018-07-08) Li, Wenyan; Hummerick, Mary; Khodadad, Christina; Buhrow, Jerry; Spencer, Lashelle; Coutts, Janelle; Roberson, Luke; Tuteja, Anish; Mehta, Geeta; Boban, Mathew; Barden, MichaelBacterial biofilms are an important and often problematic aspect of life on earth and in space. Microbial contamination onboard the International Space Station (ISS) continues to pose mission risks, both to crew health and hardware reliability. In order to optimize the design of the future space exploration vehicle for long term missions, new technologies are needed to control the habitat’s microbial environment over multiple years. Among the emerging technologies for combating biofilm, new surface coatings show promise for preventing biofilm formation. This approach aims to interrupt the critical initial step of biofilm formation (cell attachment) through surface modification. When successfully developed, biofilm resistant coatings can eliminate/reduce the need for disinfectants, and avoid the development of “superbugs,” thus offering distinctive advantages for biofilm prevention during long term missions. Initial results at KSC showed that omniphobic coatings are promising candidates as biofilm resistant materials. Parabolic flight experiments also verified their physical properties under microgravity.Item Corrosion on Mars: An Investigation of Corrosion under Relevant Simulated Martian Environments(48th International Conference on Environmental Systems, 2018-07-08) Calle, Luz; Li, Wenyan; Buhrow, Jerry; Johansen, Michael; Calle, CarlosThe goal of this research is to develop a systematic approach to understand corrosion of spacecraft materials on Mars by conducting a literature search of available data relevant to corrosion in the Mars environment and by performing preliminary laboratory experiments under relevant simulated Martian conditions. This project was motivated by the new found evidence for the presence of transient liquid brines that coincided with the suggestion by a team of researchers that some structure degradation cannot be attributed to rock scratching and may be caused by corrosive interactions of brines with spacecraft materials. An extensive literature search on data relevant to Mars corrosion confirmed the need for further investigation of the effect of the Mars environment on the materials used for spacecraft and structures designed to support long-term surface operations on Mars. Simple preliminary experiments, designed to look at the interaction between AA7075-T73 aluminum alloy and the gases present in the Mars atmosphere, at 20 degree C and a pressure of 633 Pa, showed that there is a significant interaction between the small amount of oxygen present in the Mars gas and the alloy when there is a scratch that removes the protective aluminum oxide film. There are many other important components of the Mars environment that can affect this interaction such as: the photo-catalytic effect of radiation on the oxidizing species, and the effect of salts in Martian soil. These initial experimental results provide strong justification for further investigation of the corrosion mechanism of materials relevant to long-term surface operations in support of future human exploration missions on Mars.Item Effects of Surface Treatments on Stainless Steel 316 Exposed to Potable Water Containing Silver Disinfectant(49th International Conference on Environmental Systems, 2019-07-07) Li, Wenyan; Buhrow, Jerry; Diaz, Angie; Irwin, Tesia; Calle, Luz; Callahan, MichaelSilver has been selected as the forward disinfectant candidate for potable water systems in future space exploration. To develop a reliable antibacterial system that requires minimal maintenance, it is necessary to address relevant challenges to preclude issues for future missions. One such challenge is silver depletion in potable water systems. When in contact with various materials, silver ions can be easily reduced to its metallic state or form insoluble compounds. The same chemical properties that make silver a powerful antimicrobial agent also result in its quick inactivation or depletion in various environments. Different metal surface treatments, such as thermal oxidation and electropolishing, have been investigated for their effectiveness in reducing the depletion of silver disinfectant from potable water. However, their effects on the metal surface microstructure and chemical resistance have not often been included in the studies. This paper reports the effect of surface treatments on SS316 exposed to potable water containing silver ion disinfectants. Early experimental results showed that thermal oxidation, when compared to electropolishing, resulted in a thicker oxide layer and a compromised corrosion resistance of the SS316.Item Silver Foam as Long-Term Passive Biocide to Potable Water Systems(49th International Conference on Environmental Systems, 2019-07-07) Irwin, Tesia; Li, Wenyan; Buhrow, Jerry; Diaz, Angie; Calle, Luz; Callahan, MichaelSilver is being considered as the biocide for future exploration missions. Maintaining microbial control in spacecraft potable water storage and delivery systems is a significant challenge for long-duration human space exploration. The current electrolytic-based silver ion dosing system still has some challenges to be addressed and there is a need for a reliable passive silver biocide delivery mechanism. This paper describes the early stage development of a silver-based composite foam as an alternative silver dosing release technology, either to be used as a standalone, or in conjunction with the electrolytic-based systems to increase the overall system reliability. Composite foam, containing silver chloride nano particles, was synthesized and its structural properties and silver ion release rate are being optimized. This paper concerns the design, synthesis, and optimization of the silver composite foam.