Reactive wetting and filling of boron nitride nanotubes by molten aluminum during equilibrium solidification

Significance Statement

Aluminum as well as its alloys has been extensively used in automotive and aerospace applications owing to its lightweight and selected materials attributes. Therefore, aluminum with sufficient strength have been fabricated only that their load bearing capacity is still low for critical structural components applications. For this reason steel and other expensive titanium alloys have been used consequently resulting in more weight, higher fuel cost, and increased operation cost.

To address this issue more researchers have focused on developing high strength and lightweight aluminum composites. Carbon nanotube reinforced aluminum composites been considered and researched widely. However, integration of carbon nanotubes in aluminum matrix is faced with major challenges of poor dispersion and oxidation of the carbon nanotubes at temperatures exceeding 400°C. For this reason, high temperature processing methods such as hot rolling, forging, and casting cannot be employed easily without damaging carbon nanotubes.

Boron Nitride nanotube as an analogue of carbon nanotube with alternate nitrogen and boron atoms has unique mechanical properties. Boron nitride is resistant to oxidation at temperatures around 1000°C. Aluminum melting point is approximately 660°C; therefore, boron nitride opens up the opportunity of manufacturing boron nitride nanotube aluminum reinforced composites through casting.

In a recent paper published in Acta Materialia researchers led by Professor Arvind Agarwal at Florida international University prepared boron nitride nanotubes integrated with molten aluminum to make a composite using the equilibrium solidification method. They were able to investigate the interfacial phenomena as well as the reactions between the nanotubes and the molten aluminum.

The authors obtained long and fine nanotubes in the form of boron nitride fibril balls. These nanotube fibers were then mixed with aluminum pellets in a crucible and then heated up to 700 °C in a muffle furnace. The molten mixture was then stirred to obtain a homogeneous mix. Thereafter, the mixture was soaked and allowed to cool to ambient temperature.

The authors observed that the boron nitride nanotubes survived the high temperature as well as reactive conditions that were involved in aluminum melting. Limited interfacial reaction occurred which led to traces of aluminum nitride and aluminum boride compounds formed. However, aluminum nitride was observed as the principle product, and this led to enhanced interfacial wetting. Computations based on the surface energies indicated improved work of the interfacial adhesion owing to the formation of aluminum nitride.

Boron nitride nanotubes were seen to be well integrated in the molten aluminum matrix. This signified that the resulting aluminum nitride led to excellent interfacial wetting. The authors also reported capillary induced high temperature filling of the boron nitride nanotubes by the aluminum. This filling was enhanced by aluminum nitride formation. The filling attribute was however dependent on nanotube wetting which further improved when aluminum-boron nitride nanotube reaction progressed to form aluminum nitride.

The results of their study indicate controlled reaction induced appreciable wettability of the boron nitride nanotubes by molten aluminum. This supports the development of high strength boron nanotube reinforced aluminum composites by the casting method.

Reactive wetting and filling of boron nitride nanotubes by molten aluminum during equilibrium solidification- Advances in Engineering

Figure credit of Acta Materialia

About The Author

Dr. Arvind Agarwal is a full professor in the Department of Mechanical and Materials Engineering at Florida International University (FIU), Miami, FL.  He also serves as the Associate Dean of Research, College of Engineering and Computing and Director of Advanced Materials Engineering Research Institute (AMERI), which is a major user facility for materials characterization and nanofabrication at FIU.

Prof. Agarwal obtained his B.S. from Indian Institute of Technology (IIT) Kanpur in Materials and Metallurgical Engineering and Ph.D. from the University of Tennessee at Knoxville. After his PhD, Prof. Agarwal worked in the industry as a Materials Scientist at Plasma Processes Inc., Huntsville, AL, USA, for 3 years, before embarking on an academic career.

Prof. Agarwal’s current research interests include plasma and cold spray, surface engineering, spark plasma sintering, carbon nanotube, boron nitride nanotube and graphene reinforced composites and coatings, nanoindentation and nanotribology, and mechanical properties of low dimensional and biological materials. His research has been funded by NSF, ONR, AFOSR, ARO, NASA, DOE and industries.

Prof. Agarwal has published more than 260 technical articles, which includes more than 200 peer-reviewed journal articles, 1 co-authored book, 7 edited books and 3 book chapters. Prof. Agarwal has received numerous awards including National Science Foundation’s (NSF) prestigious CAREER award and FIU President’s Council Outstanding Professor Award. He was inducted in 2012 class of Fellows of ASM International (FASM).

About The Author

Dr. Sudipta Seal is a Peagus Professor and USC Distinguished Professor in the Department of Materials Science & Engineering at University of Central Florida (UCF), Orlando, FL, USA and the Chair of the Department of Materials Science & Engineering at UCF. He also serves as the Director of NanoScience Technology Center and Advanced Materials Processing and Analysis Center. Dr. Seal’s research interests include processing of functional materials, nanobiotechnology, surface engineering, coatings, nanoenergetics, nanotoxicity and advanced analytical tools.

His research has been funded by NSF, DOD, MDA, NIH, NASA and industries. Dr. Seal has published more than 450 technical articles, edited/ authored 14 books and has 63 awarded patents. Dr. Seal is a Fellow of ASM, AAAS, AVS, IoN, NAI, AIMBE, ECS, JSPS (NIMS-Japan) and Royal Academy of Eng. Dr. Seal has received ONR Young Investigator Award, UCF CECS Dean’s Faculty Excellence Award, ASM IIM Award, Alexander Von Humboldt Research Fellowship, Sci. Spectrum Trail Blazor Award, Central Florida Engineers Week Award and 2014 Schwartz Tech Award.

About The Author

Dr. Benjamin Boesl is an Assistant Professor in the Mechanical and Materials Engineering Department at Florida International University. He currently serves as the director of the Composites Laboratory and Assistant Director of the Advanced Materials Engineering Research Institute (AMERI). Prior to his appointment at FIU, Dr. Boesl was awarded the ORAU Post-doctorate research fellowship to conduct research at the US Army Research Laboratory in Aberdeen, MD for 3 years.

His research focuses on advanced materials response and design and has a significant focus on in situ electron microscopy. He has been a PI or Co-PI on federally funded research from ARL, AFRL, AFOSR, ONR, and the FAA. He has published over 30 peer-reviewed journal articles and over 50 conferences presentations and 3 patents. He has received multiple awards for research including FIU “Top Scholar” in 2016. He is also an active member of multiple professional societies including TMS, MRS, ASME, and AIAA.

About The Author

Dr. Ankur Gupta is Materials Scientist at the Persimmon Technologies Corporation, Wakefield, Massachusetts. He received his Ph.D. in Materials Science and Engineering from the University of Central Florida, Orlando in 2017, M.Tech. in Materials and Metallurgical Engineering from Indian Institute of Technology (IIT) Kanpur in 2011 and B.Tech. in metallurgical engineering from MNIT Jaipur in 2009. His research interest includes thermal spray of electrically insulating magnetic materials, and graphene oxide reinforced metal matrix and ceramic matrix composite coatings, nano-biomaterials for healthcare and biosensing applications, and structural and chemical characterization of materials using high-resolution transmission electron microscopy (HRTEM). He has also worked on atomic layer deposited cerium oxide thin films for anti-inflammatory applications. He is a recipient of AVS Dorothy M. and Earl S. Hoffman award 2015, UCF Graduate Student Research Scholarship 2015, MNRD scholarship from 2009-2011.

He has authored a book chapter on superhydrophobic surfaces and published over 26 research articles in the peer-reviewed international journals. He is also a reviewer of Metallurgical and Materials Transactions A, Journal of Thermal Spray Technology, Surface and Coating Technology, Tribology International, Applied Materials and Interfaces, Journal of Composite Materials, Materials Express etc.

About The Author

Pranjal Nautiyal is a Doctoral student in the Department of Mechanical and Materials Engineering at Florida International University (FIU), Miami, USA. He works in Plasma Forming Laboratory, Nanomechanics and Nanotribology Laboratory and Advanced Materials Engineering Research Institute (AMERI) at FIU. His research interests include nanocomposites, nanomaterials, nanomechanics, in situ mechanics of advanced materials and cold spray. Pranjal is the recipient of the prestigious Presidential Fellowship Award from FIU Graduate School.

Pranjal has published 14 journal articles, filed 1 US patent and delivered presentations in National and International conferences, meetings and symposia. He has won awards for his research presentations in different forums. Pranjal is an active student leader, currently serving as the Secretary of the Council of Student Organizations in FIU, the Chair of Material Advantage Student Chapter at FIU and the member of the Student Advisory Board to the Advanced Materials Engineering Research Institute at FIU.

Reference

Pranjal Nautiyal, Ankur Gupta, Sudipta Seal, Benjamin Boesl, Arvind Agarwal. Reactive wetting and filling of boron nitride nanotubes by molten aluminum during equilibrium solidification. Acta Materialia 126 (2017) 124-131.

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