nanomaterials - tahan
TRANSCRIPT
Nanomaterials
Brent AugustineSTS 201
1/25/05
Questions to be answered…
! Nanomaterials…..
! What are they?
! What makes them unique?
! How do they work?
! What are some applications?
! Where is it headed?
What are Nanomaterials?
! Nanomaterials are anybulk material thatcontain embeddednano-sized particlesthat are no larger than100 nm in any onedirection.
COURTESY OF STEVEKENIATH, MICHIGANMOLECULAR INSTITUTE
What makes them unique?
! When combined with nanoparticles,nanomaterials gain a slew of propertyenhancements such as…! Improved strength
! Increased hardness
! Improved ductility
! Improved tensile properties
! Resistance to tear
! And many other material enhancementproperties
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What makes nanomaterials unique?
! Nanomaterials behavethe way they dobecause when thenanoparticle grainsoverlap and reinforcethe material, many ofthe qualities of thenanoparticles areinherited by thematerial causing theadditional propertyenhancements.
Applications of how they work…
! The Hall-Petch model:
! Inverse relationship between grain size and yieldstrength
! Theorized with microparticles, proven to hold withnanoparticles as well
! Nanocrystalline Fe powder grain size reduced from33nm-8nm
! Showed increase in hardness and decrease in fracturestress
http://www.matsci.ucdavis.edu/MatSciLT/EMS-174L/Files/HallPetch.pdf
Carbon Black
! Carbon Black in tires:! Carbon Black,
produced by thepartial combustion ofnatural gas, has longbeen used as areinforcement inrubber tires
! Improved strengthand tensileproperties, tear andabrasion resistance,and increasedhardness
www.cf.ac.uk/engin/ staff/pjb/subpages/pfc.html
Carbon Black cont…
! Absolute strength ofnanocomposite notlinear
! Initially increaseswith the addition ofcarbon because ofthe reinforcementfrom carbon grains
! Then decreasesdue to the dillusioneffect when toomuch carbon blackis present
www.konimpex.com.pl/ phtml/sadza_techniczna.php
Courtesy of Bridgestone
Metal Nanocomposites
! Metals can be made intonanocrystalline materials that performbetter than regular metals.
! Roll copper at the temperature of liquidnitrogen
! Then, heat to around 450 K
! Results in ‘bimodal’ structure with micro-meter sized grains and nanocrystallinegrains
! Increases strength and hardness ofmetal because of the nanocrystallinegrains
! Shows high ductility as well, largergrains stabilize tensile deformation ofmaterial
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Reinforced Polymers
! One particular area of research has been the reinforcement ofpolymers coupled with Polyhedral Oligomeric Silsesquioxanes(POSS)
! Allows for greater mechanicals due to the entrainment with thepolymer chains
! Connections with polymer chains:
Current Industrial Applications
! Carbon black rubber filler in tires
! $4 billion industry
! Hummer H2
! Nanocomposites line the bed of the truck
GM’s 2005 Hummer H2cargo bed uses about 7 lbof molded-in-color TPOnanocomposite parts.
www.plasticstechnology.com/.../ 200411fa2.html
Industrial Applications
! Wilson Company
! Have added nano-sized silicon dioxidecrystals to rackets toincrease their power
! Also, coated tennisballs with a butyl-based nanoparticlethat cuts airpermeation in half andmakes them lastlonger
http
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Solar converting polymers
! Polymers embedded with copper basednanocrystals (copper indium diselenide)
! When exposed to energy source (photons orphonons):! Free charges of particles are generated and
transported along the polymer to electrodes
! Effectiveness due to ability of the carriers toarrive to the electrodes without recombiningwith oppositely charged particles
! Efficient because nanocrystals are able toconvert both photons and phonons
Future of nanomaterials
! Major influence on currentindustries
! Must ensure risk factorsare eliminated whendealing with the unknown
! TechnologicalSomnambulism cnn.com