Nanocomposites. INM Leibniz Institute of New Materials Stefan Brück Webinar

Transcription

1 Nanocomposites INM Leibniz Institute of New Materials Stefan Brück Webinar

2 Agenda Nanoparticles, The Key Element Nanoparticles + Matrix +??? = Nanocomposite 2D Nanocomposites: Coatings Examples of Applications 7/1/2014 presentation du projet 2 7/1/2014 2

3 Particles with diameter up to 100 nm Why nanoparticles? d < 1/20 λ rule of thumb No light scattering in transparent matrix when diameter smaller then 1/20 of wavelength Which nanoparticles? Chemical composition: Si 2, Al 2 3, Zr 2, Ti 2, Metals,... Morphology: spheres, needles, flakes/platelets Third or functional property: Passive e.g. refractive index Active e.g. non linear optical properties NL 3 7/1/2014 3

4 Properties by nanoparticles ptical properties No light scattering by NP, color can be selected Adaptable refractive index e.g. for light guide adhesives UV / IR protection with absorbing nanoparticles Electrical properties Electical conductive but transparent coatings Printable electronics Magnetic properties (superparamagnetic iron oxide < 30 nm) Temperature increase in magnetic field for bond/disbond-on-command Rheological properties Adapting viscosity of reactive mixtures Thermo-/mechanical properties Reduction of thermal expansion Scratch and/or abrasion resistance Anti-Friction, corrosion protection 7/1/2014 4

5 Nanocomposite Basics Nanocomposite is combination of matrix and nanoparticle reinforcement Elements of polymer matrix nanocomposites Free linear polymer chains, loops, net connections Particles and particle-particle contacts Polymer-particle contacts: Interface layer 5 7/1/2014 5

6 Interface layer the third compound in nanocomposites! Low degree of order High degree of order Particle diameter / nm Attachment of polymer chains on particles with high specific surface area Formation of interface layer (phase) with higher degree of order Interface layer is substancial part of composite! 7/1/2014 6

7 INMs Nanomer materials organo silane based sol-gel type structures: hybrid structures polymeric chains polymer type structures NAN- MER nano scale particles e.g. Zr 2, Al 2 3, Ti 2 Cu, Ag, Pt, CdS, Fe x,... ceramics, metals, semiconductors glasses 7 7/1/2014 7

8 Chemistry S i S i [ M ] H 3 C S i C H 3 S i S i ( C H 2 ) 2 ( C F 2 ) n C F 3 C H 3 S i Surface modified nanoparticles Inorganic network rganic network (Silsesquioxanes, Silicones) Inorganic network [M] = Ti, Zr, Al,... Mixed inorganic-organic network 8 7/1/2014 8

9 Coating (wet processing) Processing Curing Heat Room temperature C Dip coating Screen printing Light D T, IR, Laser Spin coating Roller coating NIR,UV, VIS, Laser Spray coating flooding e - and many more including powder coating. Electron beam 9 7/1/2014 9

10 TC (e.g. IT) applications: Wet chemical deposited TC coatings Nanosized Indium tin oxide (10-15 nm) Transparent electrodes for: - Displays - Touch screen panels - Solar cells - Smart windows - Printed electronics IR reflecting materials: energy saving glass Antistatic coatings Advantages of wet chemical deposited TC coatings: Cost-effective processing: roll to roll, printing, spraying high speed, low material consumption Printed and patterned IT coatings of the INM on PET foil rganic photodiode (PD)** with printed IT coating of INM as bottom electrode [1] ** PD was fabricated in Joanneum Research-NMP, Weiz, Austria direct patterning by printing, no additional etching [1] S. Heusing et al., Proc. SPIE, Vol (2008) 69992I [2] M. Tuomikoski et al., Proc. SPIE, Vol (2006) /1/

11 Properties of TC coatings 7/1/

12 Photocatalytic Coatings Principle: Ti 2 is a semiconductor (bandgap 3.2 ev) Irradiation with UV-A electrons are promoted to CB formation of electron/hole-pairs. Migration of e- and h+ to the surface. With water (e.g. moisture) aggressive radicals are formed UV-Light <388 nm CB conduction band forbidden zone / Band gap 3.2 ev. 2- +H + H 2. 2 H 2 valence band VB. H + H + 7/1/

13 Synthesis of Photocatalytic Coatings State of the Art: Multi layer systems prevent catalyst poisoning by Na + ions prevent degradation of substrate INM approach: Nanosized anatase titania (9-12 nm) Unique single layer system based on modified nanoparticles with fluoro organic silanes Wet film Drying Curing Film with gradient in Ti 2 -concentration Shrinkage due to curing Single Layer Coating: ne step coating application Transparent coatings Thin coatings (1-1.5 µm) High photocatalytic activity Color, look and feel substrate is preserved Substrate Substrate matrix sol (hydrolysed silianes, solvents etc.) F-modified nano Ti 2 particles particulate silica 7/1/

14 Photocatalytic Coating Applications Self-cleaning surfaces Photocatalytic degradation of dirt, soot on surfaces: tent textiles, fassades, roof tiles, outdoors equipment etc. Antimicrobial effect: Photocatalytic degradation of microbes on sanitary surfaces, in medical installations etc. Anti growth effect: No growth of algae, lichens etc. on outdoor equipment 7/1/

15 Pigmented, fine-textured tribological composite materials

16 Principle I: Low friction by solid state lubricants: example boron nitride BN shear stress scheme of hexagonal BN structure SEM micrograph of a sub-µm BN high friction force perpendicular to layered structure low friction force parallel to layers 16

17 Principle II: Gas diffusion barrier by inorganic platelets/ Hartstoffe in Polymermatrix platelets: e.g. micro glass flakes permeability Principle III: Wear resistance by hard particles hard particles: e.g. Si3N4 solubility coeff. diffusion coeff. longer diffusionpathways pathways for gas molecules Pc Pp p 1 L f W 2 Pc Permeability of filled polymer Pp Permeability of unfilled polymer Substrate Metall-Substrat Platelets platelets 17 matrix Matrix p Volume fraction of polymer f Volume fraction of filler Nano-Particles hard particles L Aspect ratio W

18 coating Principle IV: Composite with fine-textured morphology Combination of lubricants / platelets / hard particles in a polymer matrix tortuous path 2, H 2, S 2 polymer matrix substrate hard particles lubricant platelets ( inactive in lubrication effect) in a roof-tile arrangement W A1, INM ggmbh Composite with fine-textured morphology 18

19 coating The friction process: low friction with controlled wear relative movement friction counterpart controlled transfer film formation stabilising hard particles metal substrate New unexpected effects by introduction of inactive platelets in low friction coatings? 19

20 coefficient of friction µ Reibungskoeffizient µ ptimisation of the hard filler content: example Si 3 N Reihe Si3N4 E05 mit 30% BN 110 / 5% LS / 10% FL 4 0,4 0,35 0,3 0,25 0,2 0,15 0 wt.-% 1.25 wt.-% 2.5 wt.-% 5.0 wt.-% 10 wt.-% 15 wt.-% A 200 / 0% Si3N4 E05 A 233 / 1,25% Si3N4 E05 A 234 / 2,5% Si3N4 E05 A 235 / 5,0% Si3N4 E05 A 236 / 10% Si3N4 E05 A 237 / 15% Si3N4 E05 0,1 0,05 2,5 wt.-% Si 3 N Runden rounds Introduction of hard particles with moderate hardness (HU = 1500 MPa) gives possibility for further improvement 21

21 Corrosion resistance of fine-textured low friction coating in neutral salt spray test (SST) low friction coating on mild steel coating thickness 25 µm 600 h SST 600 h SST coating partially scratched off no delamination no blistering no subsurface migration 22

22 Highly structured barrier layers

23 Influence on the platelet arrangement to improve barrier effect SEM analysis on cross-sections of foils after brittle fracture low degree of platelet alignment without orienting additive (sample F) high degree of platelet alignment with orienting additive (sample L) W A1, INM ggmbh Highly structured composite material for protection 24

24 Measurement set-up for 2 -permeation xtran Permeation Device from MCN (Mineapolis, USA) According to ASTM D3985 sweep gas: N 2 testing gas: µm thick coating layer prepared as a foil 25

25 permeation coefficient Permeationskoeffizient [cm 3 mm/m 2 d] Influence of platelet alignment on barrier properties: 2 - gas permeation measurement 7 6 6,5 permeation coefficient = 0 wt.-% 10 wt.-% platelets 2 volume layer thickness 20 wt.-% platelets time area [cm 3 ] [mm] [d] [m 2 ] ,6 2,5 3,2 2,6 2,2 1,4 matrix with higher crosslinking density 0 A D E W F L X optimised matrix Beschichtungsnummer sample platelets = aligned SEManalysis 26

26 Contacts Germany INM - Leibniz Institut für Neue Materialien ggmbh Campus D Saarbrücken Dr. Cenk Aktas Cenk.Aktas@inm-gmbh.de Stefan Brück Stefan.Brueck@inm-gmbh.de +Composites Webseite 7/1/