Structural Boron Nitride Nanotube Composite Development February 21, 2014 Catharine Fay NASA Langley Research Center Advanced Materials and Processing Branch Strategic Partner: National! Institute of! Aerospace! Strategic Overview • Vehicle weight is a primary driver for most NASA missions. Reducing vehicle weight can: – Expand mission capability – Reduce launch costs – Reduce fuel consumption – Systems analysis shows that reducing materials mass by 20% leads to a 30% reduction in launch vehicle gross weight – Same study indicates a 50% reduction in materials mass reduces launch vehicle gross weight by >60%, enables potential single stage to orbit designs – Additional multifunctionality: thermal, radiation protection, sensing capabilities, no corrosion Effect of Materials Mass Reduction on Launch Vehicle Gross Weight Project Goal Potential Impact: Produce advanced BNNT composites with higher thermal stability, lightweight, no corrosion, tough, and radiation shielding effectiveness 2 Properties of Materials for Vehicle Structure 1000 @ RT Specific Modulus, GPa/(g/ cm3) Specific Modulus, GPa/(g/cm3) 300 800 600 400 M46J 250 The structural material properties for nanotubes significantly exceed those of current SOA materials. Nt/P 200 150 BeAl 100 50 0 SWCNT BNNT SiC/Be IM7 Nt/Al TiFoamSand Al2O3/Al M46J IM7 CFRP Al 2219CFRP AlFoam TiAl 0 0.5 1 1.5 2 2.5 3 3.5 Specific Strength, GPA/(g/cm3) 200 Baseline Materials 5-10 years (TRL = 4-6) 10-20 years + (TRL = 1-3) 0 0 20 40 60 80 100 120 Specific Strength, GPA/(g/cm3) Charlie E. Harris, M. J. Shuart, H. Gray, NASA/TM-2002-211664 140 160 180 Properties of Materials for Vehicle Structure 1000 Specific Modulus, GPa/(g/ cm3) Specific Modulus, GPa/(g/cm3) 300 800 600 400 BNNT @ 700⁰C 250 200 150 SiC/Be 100 TiAl 50 0 0 0.5 1 1.5 2 2.5 3 3.5 Specific Strength, GPA/(g/cm3) 200 Baseline Materials 5-10 years (TRL = 4-6) 10-20 years + (TRL = 1-3) 0 0 20 40 60 80 100 120 Specific Strength, GPA/(g/cm3) Charlie E. Harris, M. J. Shuart, H. Gray, NASA/TM-2002-211664 140 160 180 Technology Areas TA 6 7, 10 and 12 Life Support Membranes (e.g. water, CO2) Structure: Stronger/ Tougher/Lighter Components Micrometeoroid Protection Ultralightweight Wire Insulation High Temperature Components Radiation Shielding/ Protection Thermal Protection Systems Lightweight Tethers 5 Team Technical Group Lead Catharine Fay1 Synthesis & Produc&on Radia&on Joseph Lee2 Sheila Thibeault1 Godfrey SauJ6 Hoa Luong3 Diagnos&cs Paul Danehy2 BNNT Team Systems Analysis Kevin Earle5 Jennifer Inman2 Stephen Jones2 Modeling Peter Gnoffo4 Derek Liechty4 Vesselin Yamakov6 Advanced Materials and Processing Branch, LaRC Research Directorate Advanced Sensing and Optical Measurements Branch, LaRC Research Directorate 3 Materials Experiments Branch, LaRC Research Directorate 4 Aerothermodynamics Branch, LaRC Research Directorate 5 Space Mission and Analysis Branch, LaRC Systems Analysis & Concept Directorate 6 National Institute of Aerospace 1 2 Characteriza&on & Processing Cheol Park6 Glen King1 Sharon Lowther1 Sang-‐Hyon Chu6 Luke Gibbons6 Jin Ho Kang6 Amanda Tiano6 Samantha Applin6 Wanda Gresham3 Hyunjung Kim6 NASA BNNT Product Strategy Steps Synthesis Production BN Nanotubes • Two trained operators. • Runs on average 3 days a week 4 hours per day. (not including startup and shutdown/harvesting) • To date has produced approximately 9 grams of material. • Production rate between 15 and 20 mg per hour. • Enables purification and dispersion studies. • Enables fabrication of yarns mats and other structural components. • Enables Material Transfer Agreements to NIA and Universities. 7 BNNT Purification Progress • Acid Treatment Purification Using nitric acid, remove boron nanoparticles (an impurity) from sample. • • • Thermal Purification Use heat to remove boron nanoparticles and potentially remove boron oxides (i.e. water soluble impurities). • • • Surfactant Purification Using surfactants, remove all impurities, which includes boron nanoparticles and amorphous and crystalline BN. • • Boron nanoparticles removed Noticeable damage to the nanotubes resulting in poor quality of the acidtreated sample Acid-treated structural mats have no integrity Boron nanoparticle removal alternative Assumption: the darker the BNNT, the higher the boron content/impurity content; visible color change from a darker to a lighter-colored material Further analysis and investigation in progress Least harmful method to purifying the nanotubes Potential removal of crystalline BN (which cannot be removed via other listed purification methods) Further analysis and investigation in progress; will include sonication and centrifugation as well* Dispersion studies DMF DMF/ Toluene Toluene Acetone • By surveying a variety of solvents/co-solvents, surfactants, and polymers (A), a solubility region for BNNTs was established (B) using Hansen solubility theory. • Extending this knowledge, we generated BNNT structural composites (C) with a plethora of interesting properties (D). Triton X-100 PVP SDBS CTAB Before hot-press Frozen dispersion fabrication method 1 inch 20% BNNT PMMA 12% BNNT PU After hot-press 30% BNNT PU 30% BNNT PU (drop) 50% BNNT CP2 67 % BNNT PAN 10% BNNT PVA 50% BNNT PVA 50% BNNT PVA + sonication 75% BNNT PVA 1 inch New fabrication method simplifies processing for high weight nanocomposites This approach can be used to fabricate BNNT + polymers/ epoxies and lock in the dispersion conditions The “frozen dispersion” step is intermediate - the sample is consolidated during hot-pressing 67% BNNT-PU Pressed 67% BNNT-PU PU - Polyurethane PMMA - Poly(methyl methacrylate) PVA - Polyvinyl alcohol PAN - Polyacrylonitrile CP2 – LaRC CP2 Polyimide BNNTTEM Purification, Dispersion, & Spinning images BNNT in Chlorosulfonic (CSF) Acid (Superacid): Spontaneous dispersion and debundling Need purified BNNT for spinning BNNTs Non-nanotube BN AFOSR Low Density Material Program Review Wright Brothers Institute, Dayton (OH), 4 June 2012 Continuous fiber spinning technology for armchair quantum wire CNT superacid spinning CNT spun fibers Liquid crystalline state FIBER SPINNING CNT spinning • BNNT Pasquali Superacid Spinning in collaboration with Rice University Matteo Departments of Chemical Biomolecular Engineering and Chemistry, • &BNNT Mat/Sheet Formation (filtering) Stretching BNNT Sheet SEM images of Stretched Aligned SEM images of Stretched Aligned The Smalley Institute for Nanoscale Science &Mechanical Technology à Composite Tape à Tests MWNT Sheets MWNT Sheets The Ken Kennedy Institute for Information Technology [email protected] Sheet Aligned Sheet Rice University, Houston, TX; Collaboration with Teijin, manufacturers of Twaron (PPTA) and Toho Tenax (C fibers) Stretching FSU Rice University (Prof Matteo Pasquali) FSU Stretched 35% University aligned MWNT (Wang/Liang) Stretched 53% aligned MWNT Florida State Stretched 25% aligned MWNT 11 Three Goals for BNNT Modeling • Define the environment in which tubes now grow. – “Laser Vaporization and Plume Chemistry in a Boron Nitride Nanotube Production Rig”, JTHT, Vol. 27, No. 3, 2013 – Simulate domain for irradiated droplet suspended in space to better model convection currents – key to understanding nucleation site environment • Define the optimum environment for growing BNNTs. – Observations suggest significant formation of tubes at nucleation sites rising from heated surface, even before condensation wire is encountered – If tip growth mechanism: need to simulate nucleation of supersaturated BN from rising plume on nucleation site(s) – If root growth mechanism: need to simulate micro-droplets of liquid Boron ejected from heated surface • Melts at ~ 2600 K, Boils at ~ 5000 K at 200 psi • Simulate evolution of absorbed N2, N, and BN in micro-droplet as it rises in plume and cools – Plan to explore molecular dynamics approach of Violi et al. (A multi-scale computational approach for nanoparticle growth in combustion environments) • Explore modifications to rig by simulation to promote optimum environment. – Directed jets may be used to speed or slow the plume dynamics, possibly inducing recirculation through the hot zone rich in BN, to promote BNNT growth. Temperature Contours Around 1 mm Radius Boron Droplet Temperature Exceeding Boron Melting Point T, K 4800 4600 4400 4200 4000 3800 3600 3400 3200 3000 2800 2600 Can jets be used to: (1) Promote recirculation of micro-droplets through hot (red) zone rich in N and BN? (2) Extend the length (or time of residence) in green zone to extend life of molten micro-droplet before solidification Optical Diagnostic Techniques for BNNT • Need a detailed understand of chemistry and flow physics of nanotube generation and how the process changes under different operating conditions – Improve and validate simulation/modeling – Optimize material properties, production rate • Specific Goals: – Determine gas and melt-ball temperatures – Determine amount of B2, B, BN, N and N2 • In-situ, on-surface measurement: – optical pyrometry for surface temperature • Off-surface, gas phase measurement: – High-speed, high-resolution imaging • Shadowgraph and visible emission – Species sensitive imaging (BN PLIF) – Temperature measurements (CARS) Partnerships & Collaborations Strategic Partner National! Institute of! Aerospace! • NASA LaRC Center (5 branches) – – – – Glenn Research Center Goddard Space Flight Center Johnson Space Center Ames Research Center • Other Government – Air Force Office of Scientific Research – NIST • Commercial – BNNT, LLC – Momentive • Universities – – – – – – – – UC-Berkeley Rice University SUNY-Binghamton VA Commonwealth University University of North Texas University of New Hampshire NC State Hampton University • International – ONERA (France) – Institutode Nanociencia de Aragon (Universidad de Zaragoza, Spain) 15 BNNT enables………………… Hydrogenated BNNT Hydrogen Storage BNNT Multi-Functional All BN-BN Composite Radiation Shielding Materials Containing Hydrogen, Boron, and Nitrogen: Systematic Computational and Experimental Study Fig 2. TEM image of C60-BNNT (endo-doped) UC Berkeley The fabrication processes of BN-BN composite precursor and different BN-BN composite structures (fiber, plate composite). BCN Nanotubes BNNT B BNNT C fiber resource C N Fig 3. TEM, EELS, and Raman spectra of BCNNT. BxCyNz Nanotube (BCNNT) Development 16
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