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Particles! Workshop materials Screen printing technology Aerosol processing of materials 7/28/09 Sheryl Ehrman.

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Presentation on theme: "Particles! Workshop materials Screen printing technology Aerosol processing of materials 7/28/09 Sheryl Ehrman."— Presentation transcript:

1 Particles! Workshop materials Screen printing technology Aerosol processing of materials 7/28/09 Sheryl Ehrman

2 Particles! workshop plan 3:30-3:45 Intro to workshop, introductions to each other 3:45-4:30 Introduction to particle technology –Particle technology basics –Air pollution 4:30-5:15 Laboratory tours - flame reactor, metal powder reactor 5:15-5:45 Where are the particles, conductive pastes activity 5:45-6:45 dinner 6:45-7:45 How are the circuit boards printed? Screen printing activity. Important powder properties, flowability activity 7:45-8:45 Details about our process to make the powders, design activities 8:45-9 Wrap up and clean up

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6 Size, composition control Avoid agglomeration Quantity/cost Holy grail Our laboratory’s approach: develop processes for niche applications only one or two of the objectives required make use of aerosol approaches when advantageous Particle processing – general goals

7 Particles, how to make them Top down –Milling –Refining micron scale patterning techniques Bottom up –From atoms or molecules to clusters to particles to macroscale materials

8 Methods of making fine particles Starting from molecular level –From precursor Aerosol Combustion synthesis Thermal or plasma synthesis Solution phase synthesis Precipitation Sol gel Emulsion –Evaporation/condensation Starting from cluster level –Spray pyrolysis –Electrospray

9 Aerosol example: Cu doped ceria Water cooled substrate for particle deposition CH 4 O2O2 N2N2 Burner Nebulizer Compressed Air Rotameters Metal acetate precursors 0.3 mol /l in water R.K. Pati, S. Hou, O. Akhuemonkhan, I.C. Lee, D. Chu, S.H. Ehrman, submitted (2006)

10 Solution phase example: Fe nanoparticles K.C. Huang and S.H. Ehrman, Langmuir, in press (2006) Precipitation of iron from iron chloride in presence of sodium borohydride and trace amount of palladium ions as seeds Polyacrylic acid added as dispersing agent

11 Why the emphasis on aerosol processes in our lab? Advantages in some cases: –Rapid –Simple, less steps required –No solvents –Amenable to continuous processing –Potential for scalablity

12 Disadvantages Poor size control Poor control of aggregation Difficult to make non-oxides –Interesting alternatives - sodium coated metal nanoparticles (Axelbaum, Zachariah) in aerosol process May battle thermodynamics in mixed systems

13 Aerosol manufacturing, $$ ProductVolume, tons/yr Market $/yr Process Carbon black8 M8 BFlame Titania2 M4 BFlame Fumed silica0.2 M2 BFlame Zinc oxide0.6 M0.7 BHot wall furnace Fe, Pt, CeO M0.3 BHot wall furnace, spray pyrolysis Ref: K. Wegner, S.E. Pratsinis, Chem. Eng. Sci. 51, 4581 (2003)

14 Metal powders for conductive pastes DuPont uses 400,000 kg of precious metal per year to make their pastes Prices: Silver /ounce Gold - 950/ounce Palladium - 260/ounce Copper /pound Nickel /pound

15 General Aerosol Process Schematic Feed #1 Preparation Feed #2 Preparation Feed #N Preparation Vaporization Pumping/Compression Addition of additives Preheating © R.B. Diemer, Jr Schematic developed by R. Bertrum Diemer, DuPont

16 Aerosol Reactor Feed #1 Preparation Feed #2 Preparation Feed #N Preparation Mixing Reaction Residence Time Particle Formation/Growth Control Agglomeration Control Cooling/Heating Wall Scale Removal © R.B. Diemer, Jr General Aerosol Process Schematic

17 Aerosol Reactor Base Powder Recovery Gas-Solid Separation Feed #1 Preparation Feed #2 Preparation Feed #N Preparation © R.B. Diemer, Jr General Aerosol Process Schematic

18 Aerosol Reactor Base Powder Recovery Offgas Treatment Feed #1 Preparation Feed #2 Preparation Feed #N Preparation Treatment Reagents Waste Absorption Adsorption Vent or Recycle Gas © R.B. Diemer, Jr General Aerosol Process Schematic

19 Aerosol Reactor Base Powder Recovery Offgas Treatment Powder Refining Feed #1 Preparation Feed #2 Preparation Feed #N Preparation Treatment Reagents Waste Coarse and/or Fine Recycle Vent or Recycle Gas Size Modification Solid Separations Degassing Desorption Conveying © R.B. Diemer, Jr General Aerosol Process Schematic

20 Aerosol Reactor Base Powder Recovery Offgas Treatment Product Formulation Powder Refining Feed #1 Preparation Feed #2 Preparation Feed #N Preparation Formulating Reagents Treatment Reagents Waste Coarse and/or Fine Recycle Vent or Recycle Gas Coating Additives Tabletting Briquetting Granulation Slurrying Filtration Drying © R.B. Diemer, Jr General Aerosol Process Schematic

21 Aerosol Reactor Base Powder Recovery Offgas Treatment Product Formulation Packaging Powder Refining Feed #1 Preparation Feed #2 Preparation Feed #N Preparation Formulating Reagents Treatment Reagents Waste Product Coarse and/or Fine Recycle Vent or Recycle Gas Bags Super Sacks Jugs Bulk containers –trucks –tank cars © R.B. Diemer, Jr General Aerosol Process Schematic

22 Aerosol Reactor Base Powder Recovery Offgas Treatment Product Formulation Packaging Powder Refining Feed #1 Preparation Feed #2 Preparation Feed #N Preparation Formulating Reagents Treatment Reagents Waste Product Coarse and/or Fine Recycle Vent or Recycle Gas General Aerosol Process Schematic © R.B. Diemer, Jr. 2005

23 Particle Synthesis Setup Compressed Nitrogen Atomizer (RETEC) Diffusion Dryer (TSI Model 3062) Reactor Furnace (Lindberg) Temperature: 300 ° C ~ 1000 ° C Powder Collection (X-ray Diffraction) By-Pass (R.T. control) Precursors 0.3 M precursor in water/alcohol solution (10% by volume)

24 Colors of Copper Powders 300 ° C450 ° C600 ° C1000 ° C Cu·N Cu·N +ETOH Cu·Ac Cu·Ac + ETOH Pure Cu Image J.-H. Kim

25 Other results with alcohol Can make phase pure copper from copper nitrate Enable formation of copper acetate at lower temperatures Works for nickel nitrate too! ~ 0.1 mol % H 2 estimated, well below flammability limit in air Particle synthesis (polydisperse)

26 Temperature also important Scanning Electron Microscope Images, JH Kim Polydisperse Copper Powders Cu Cu: 600 °C Cu Cu: 1000 °C From copper nitrate with co-solvent

27 Spray pyrolysis processes (adapted from Gurav et al., Aerosol Sci. and Tech., 1993)

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29 Composition is a variable What composition will give you a melting point of 1100 K and the highest conductivity possible? What composition will give you a melting point of 1250 K and the highest conductivity possible?

30 Particle diameter is a variable We want 1 micron diameter particles Equationsd Droplet diameter dpdp Particle diameter CMpMass concentration pp Density of copper nitrate solid d dpdp dropletdry saltend particle

31 Now we want to make lots of particles Process scale up calculation

32 Wrap up Particle technology, it’s everywhere! One application, metal powders for conductive pastes, everywhere too, big business! Particle properties are important for patterning the conductive pastes Lots of chemical engineering goes into developing the process to make the metal powders!

33 So what’s a micro or nanoparticle? Micro: particle < 100 microns in diameter Nano: particle < 100 nanometers in diameter May form larger structures: agglomerates, films These can be 100’s of microns in size 500 nm Size selected Cu nps Top view of film of TiO 2 nps 100 nm CuO/CeO 2 nps Cu microparticles

34 Particles are everywhere! Pollen? Soot? Viruses? Calicivirus Polio Virus All images Bar = 50 nm Photo Credit: F.P. Williams, U.S. EPA More images for public use at Pollen

35 Beneficial particles

36 Particles (nano) in the past Lampblack (carbon black) produced in quantity by the ancient Chinese Pigments used by other civilizations several hundred years BC in glass and other ceramics Examples of nano in the not so- distant past… Ref. G. Ulrich,Chemical and Engineering News, 1984 Ref: Johnson, P. H., and Eberline, C. R., “Carbon Black, Furnace Black”, Encyclopedia of Chemical Processing and Design, J. J. McKetta, ed., Vol. 6, Marcel Dekker, 1978, pp

37 Particles in the lab Studies of reactions of halogen compounds in hydrogen flames, late 1960’s, early 1970’s 1970’s application of this towards making optical fibers Bell Laboratories research “Modified Chemical Vapor Deposition” Ref: Simpkins PG, Greenbergkosinki S., MacChesney JB, Journal of Applied Physics, 50 (9) 5676 (1979).

38 Particles in industry - Vapor-phase axial deposition of optical fiber preforms start with rod (preform) of pure silica, SiO 2 O 2 /H 2 burner produces nanoparticles of silica + Ge, Ti, B, P etc… graphite furnace to consolidate fume consolidated preform is drawn into optical fiber H 2, O 2, SiCl 4 + GeCl 4 + TiCl 4...

39 Particles in the lab – Optical behavior Size dependent optical properties CdSe nanoparticles, synthesized in solution monodisperse size, different sizes in each vial illuminated with UV light emitting different (size dependent) wavelengths of visible light phenomena result of size-dependent quantum confinement image: Felice Frankel, MIT particles: Moungi Bawendi’s group at MIT, Department of Chemistry Ref: Tobin JG, Colvin VL, Alivasatos AP, Phys. Rev. Let. 66 (21) 2786 (1991) Murray CB, Norris DH, Bawendi MG, J. Am. Chem. Soc., 115 (19) 8706 (1993)

40 Particles in the market place Commercially available nanoparticles, for example Qdots Can be functionalized to bind to specific targets Used extensively today for diagnostics in biotechnology Here, dual labeled mouse fibroblasts. Actin stained red. Nuclear membrane labeled with red and green probes, appearing yellow.

41 Nano in the lab – electronic behavior Single electron transistors a single electron excess charge on a particle markedly changes its conductive properties could eventually lead to orders of magnitude decrease in device size huge implications for computing Difficulties: –stability at T >> 0 K ? –manufacturing in quantity? –how to pattern/order them? Doped Si substrate SiO 2 insulating layer gold leads + linker molecules nanoparticles after Klein et al., Nature, 389, 699 (1997)

42 Nano in the marketplace Still waiting on this one… Meanwhile… top down getting really small, sub 0.2 micron feature size in an integrated circuit Two new nano issues –Polishing at nano level between processing steps –Small features -> contaminants = killer nano particles!!

43 Nano in the marketplace Killer particles? Rule of thumb: particle > 1/3 of smallest feature size can cause killer defect Defect detection –Performance after production –On-line, light scattering At these size scales, on-line very challenging!

44 In my lab, what do we do? As chemical engineers we develop processes for making inorganic nanoparticles and nanoparticle based materials It’s a great time for chemical engineers to get involved –Relevance of manufacturing to enabling this technology –Ability to characterize improving rapidly


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