Chapter 9 Characterization of a Heating and Quenching Apparatus for Microgravity Testing Anthony S. Torres, Jeff Ganley, and Arup Maji Abstract Microgravity experimentation enables new materials to be developed and traditional materials to be improved, which can’t be completed under terrestrial conditions. Recent developments on Heavy Metal Fluoride Glasses (HMFG’s) have shown that, when heated, there is a crystallization dependency on gravity. HMFG’s have the potential for optical transmission from 0.3 μmintheUVto7 μm in the IR region, enabling fiber optic applications such as fiber amplifiers, radiometry, and mid-IR laser technology for surgery, drilling and cutting. The problem of devitrification from heat processing prevents this material from achieving its theoretical transmission range. Past researchers have shown that crystallization of HMFG’s is suppressed in microgravity and enhanced in hyper-gravity, however further investigation is still needed for a determination of this phenomenon. In this study, a HMFG heating and quenching testing apparatus was characterized and developed for microgravity and hyper-gravity testing. The testing apparatus was developed and characterized for use on a parabolic aircraft that provides a microgravity and hyper-gravity environment for experimental testing. The apparatus was successful in processing HMFG’s, which produced crystalline and non-crystalline glasses for future studies. Keywords Heavy metal fluoride glasses (HMFG) • Characterization • Heating and quenching testing • Microgravity • Crystallization 9.1 Introduction Heavy Metal Fluoride Glasses (HMFG)s are fluoride based optical fibers that have the potential for very low optical attenuation especially in the infrared region (2–7 μm), however these glasses are extremely susceptible to crystallization. Past researchers have shown that crystallization of HMFG’s is suppressed in microgravity and enhanced in hyper-gravity, showing a crystallization dependency on gravity. The specific material used for this research is a fluorozirconate glass, a subset of the HMFG family known as ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF). The optical transmission spectrum for ZBLAN is from0.3 μm in the Ultraviolet (UV) to 7 μm in the Infrared (IR) region [1]. Many researchers have conducted studies on crystal growth under microgravity [2–7]. While these researchers have studied ZBLAN, protein crystals, and semiconductor growth in microgravity, all have noticed that crystallization processes are suppressed in microgravity. These studies used sounding rockets, parabolic flight aircraft and even a drop tower to achieve free fall. The authors also noticed that crystal growth was increased during times of high accelerations [6]. When using the parabolic flight aircraft there are periods of approximately 2-g accelerations. Varma et al. detected twice as many crystals formed during the period of high acceleration as terrestrial processed fibers. Most of these experimental programs used an automated glass heating apparatus and have limited detail to the exact science and build of the experimentation. This study focuses on the characterization of a HMFG A.S. Torres (*) Department of Engineering Technology, Texas State University, San Marcos, TX 78666, USA e-mail: ast36@txstate.edu J. Ganley Air Force Research Lab/Space Vehicles Directorate, Kirtland AFB, NM 87117, USA A. Maji Department of Civil Engineering, University of New Mexico, Albuquerque, TX 87106, USA N. Sottos et al. (eds.), Experimental and Applied Mechanics, Volume 6: Proceedings of the 2014 Annual Conference on Experimental and Applied Mechanics, Conference Proceedings of the Society for Experimental Mechanics Series, DOI 10.1007/978-3-319-06989-0_9, #The Society for Experimental Mechanics, Inc. 2015 67
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