MSE Seminar - Professor David Lashmore - University of New Hampshire
BORON NITRIDE CONTINUOUS FIBER
We are now entering a new age where structural forms based on nano-materials can be created in formats which offer game changing improvements in properties. Examples are carbon nanotube fibers and large sheets used as conductors within space craft, body armor, electromagnetic shielding, and composites which just this past year have resulted in two prestigious Edison Metals for CNT derived products.
The much more recent discovery of Boron Nitride Nanotubes (BNNT) by Cohen and Zeltl and subsequent property measurements of the individual tubes, suggest that use of BNNT’s will surpass carbon based macroforms (fibers, tapes and sheets). Their large band gap, of about 5 eV, is independent of diameter and independent of chirality. This band gap can be uniquely tuned by carbon additions or by applying a transverse electric field. The Mechanical Properties potentially exceed carbon nanotubes. For example: (1) the BN tubes maintain structural integrity at 900°C, (2) are piezoelectric, (3) their frictional forces are higher than CNTs therefore BNNT yarn strength will be significant. The high temperature properties coupled with the very high strength have the potential for a ‘game changing’ focus on new fundamental designs for high temperature composites, ropes, and tethers. BNNT fibers can form composites with ceramics, and metals whereas even CNT fibers are restricted only to polymers. These multifunctional properties are not available in any other material.
Applications for Space Craft include: (1) radiation shielding coupled with structural reinforcement, (2) strain monitoring, (3) piezoelectric actuator, (4)_ active control over spacecraft structure to minimize distortion, (5) thermal management where the heat conductor also has to be an electrical insulator, (6) with PE, for radiation shielding for both gamma and neutrons.
Professor Lashmore's PhD early research at the University of Virginia, focused on the CVD synthesis and properties of polycrystalline steel whiskers and their unique properties governed by the stress interactions between a ductile nanocore with a brittle, iron carbide matrix. This work led to a career at NIST in the electrodepositon group where, as group leader, he guided its research for almost 16 years. Initial focus was on the coating of aluminum with metals and anodic films and crystallographic relationships between growth rates and morphologies of zinc to aluminum.
At NIST his interest in nano-structural alloys resulted in five major achievements: (1) The development of a process to electrochemically produce artificial super lattices and to measure their magnetic and mechanical properties (2) A discovery, with Prof. Larry Bennett, of polymorphism in metallic glasses showing that there can be more than one type of amorphous structure each with different properties; (3) The development of a new type of metallic mercury-free dental filling to help minimize exposure of children to mercury; (4) The development of a new kind of powder metallurgy process involving coating each particle with an alloy composition, a process which eliminates composition heterogeneities; and (5) The modification of a fast diffusion process to enable the formation of difficult-to-form intermetallic alloys at very low temperatures.
He left NIST in 1993 to co-found Materials Innovation, Inc. focused on the development and production of coated metallic powders to avoid segregation and defects associated with mixing. While there co-invented with Dr. Lev Deresh and now Professor Z. Hua: (1) A highly uniform steel alloy formed from coated iron alloy powder, (2) A new kind of soft coated magnetic iron power that is now used for low core loss, high-energy efficiency electric motors, very fast response solenoids, and fuel injectors for Diesel engines. This material won the Powder Metallurgical Society’s award for invention of the year.
He also co-invented a powder compaction press and powder feed system that won TIME Magazine’s award for invention of the year.
He left Mii in 2002 to join Synergy Innovations, and develop magnetic anti-counterfeiting alloy-ink pigments, CNT synthesis, CNTs for body armor, and almost all the basic technology now used by Nanocomp which was spun out of Synergy as a separate company in 2004.
Altogether he holds 42 issued patents and over 90 archival papers. Awards include; (1) the Wall Street Journal award, (2) NASA Nano-50, (3) Recognition by the White House of Nanocomp as a National Asset, (4) Time Invention of the Year for compact P/M press (2000) (5) Power Metallurgy Award for Advanced Soft Magnetic Materials (2000), (6) American Electroplaters and Surface Finishers International Research Award, (1994), (7) The Electrochemical Society Blum Award, (1992), (8) The Electrochemical Society Electrodeposition Research Award (1989) Total citations exceed 1811.
Host: Bara Cola
Reception at 3:30 preceeding seminar outside Boggs B6