1. COLLOIDAL SILICA

2. AGENDA Colloidal silica chemistry -Physical characteristics -Types Colloidal silica manufacturing -Evaporator -Grow/UF -UltraXol Colloidal silica applications -Investment Casting -Electronics -Refractories -Coatings -Catalysts

3. Forms of Silica Colloidal Silica 4 - 100 nm Fumed: 1000 nm Precipitated: 2000 nm Gel: 1000-20000 nm * - estimated 2004 US Demand by Freedonia

4. Colloid: An intimate mixture of two substances, one of which (dispersed phase) is uniformly distributed in a finely divided state through the second substance (dispersion medium). Definition

6. Precipitated Silica (2000 nm aggregate) Fumed Silica (1000 nm aggregate) Colloidal Particle (20 nm) Sand (600 mesh) Silica sizes

7. Brownian Motion Brownian forces overcome the force of gravity SiO 2

8. Si-OH Si-O - Si-OH Al-O - Si-OH Silica Surface Hydroxyl groups and incorporated aluminum give the particle a charged surface

9. Electrical Repulsion Stability SiO 2 Na +, NH 4 +, or K + Stability of sols by electostatically inhibiting collisions

10. SiO 2 Steric Hindrance Stability SiO 2 Stability of sols by sterically inhibiting collisions

11. Gelation Aggregation of particles into chains which fill the entire volume

12. Precipitation Aggregation of particles into dense clusters sufficiently large to settle

13. Stable (charge) unstable Metastable (steric) 2134567891011 Stability versus pH pH Increased Stability

14. Particle Size Effects 20% SiO 2 20 nm 20% SiO 2 15 nm 20% SiO 2 10 nm Stability Stability increases with increasing particle size

15. Concentration Effects 10% 15 nm 30% 15 nm Increasing Concentration Dilution increases stability Increasing Stability

16. Increasing Concentration Increasing Particle Size Unstable Stable 1115 1130 1140 10502329 1060

17. 2134567891011 Increased Stability 70 nm 20 nm 4 nm Stability - Effects of pH, Particle Size

18. 2134567891011 pH Increased Stability Concentration pH Effects 10% concentration 30% concentration

19. Temperature Effects gelation stable 32 o F 210 o F precipitation High temperature Freezing Increases concentration

20. 2134567891011 pH Increased Stability Ionic Strength Effects 2000 - 5000  mhos <2000  mhos >5000  mhos

21. Ionic Strength Effects Na + Ca 2+ Al 3+ Increasing Ionic Strength Increasing Stability

22. Oppositely Charged Particle Results in precipitation or flocculation

23. Stability Summary  Minimum stability in pH 4 to 7  Increased stability with larger particle diameters  Increased stability with lower concentrations  Decreased stability with higher ionic strengths  Stability dependent on order of addition

24. Colloidal Silica Specifications PARTICLE SIZE Titration -Method we use to measure particle size -Accurate for smaller particle sizes Light Scattering -Inaccurate for small particle sizes Transmission Electron Microscopy (TEM) -Most Accurate -Only used during product development

25. Colloidal Silica Specifications POLYDISPERSITY Measures particle size distribution Light Scattering gives inaccurate result TEM gives good results

26. COLLOIDAL TYPES Standard Colloidal Silica 2-125nm particle size Sodium, Potassium or ammonia stabilized 15 -50% solids level Narrow/Broad particle distribution Anionic Surface Charge Deionized/Acid Sol 2 -125nm Particle size (currently only 20nm) Low pH Slightly anionic surface charge

27. Organosols Colloidal Particles Dispersed In Organic Solvents

28. R O H O R O H O H O R O H O R SiO 2 core R O H O R O H O H O R O H O R SiO 2 core Polar solvent Organosol Silica in hydrophilic solvents

29. Colloidal Metal Oxides   Alumina   Silica/Alumina   Titania   Zirconia   Tin oxide

30. Metal Oxide Sols Properties  Low and high pH  Homogenous particles  Particle size less than 15 nm  Positively charged

31. ++ SiO 2 + + + + + + + + + + + + homogeneous metal oxide ++ SiO 2 + + + + + + + + + + + + Coated Metal Oxide

32. Coated Metal Oxide Types  Alumina  Ceria  Others  Zirconi a  Titania Properties Low pH Cationic Charge Behave more like coating metal 2 - 125nm particle size

33. DOPED SOLS - - Si - - - - - - - - - - - - - - - - - - - Alumina, Ceria, Titania, & Zirconia

34. DOPED SOLS PROPERTIES High pH Anionic Surface Charge More stable than standard sol 2- 125nm particle size

36. Ion Exchange COLLOIDAL SILICA MANUFACTURING EVAPORATOR Sodium Silicate Reactor Water/Caustic Heal As particle grows, water is evaporated off

37. COLLOIDAL SILICA MANUFACTURING GROW/UF Sodium Silicate Ion Exchange Reactor Water/Caustic Heal Ultra Filtration Unit

38. COLLOIDAL SILICA MANUFACTURING ULTRAXOL Sodium Silicate Reactor DI Resin Caustic Ultra Filtration Unit

39. PILOT PLANT CAPABILITIES Drum size quantities UltraXol Capabilities Grow/UF Deionization

41. Applications BinderCatalysts, refractories, ceramics Abrasion resistanceFilms, coatings, paints AbrasionPolish, cleaning Better Image formationPrinting, photography Protein coagulantAnimal wastes, juices,wine Strength increasePaper Drainage aidsPaper Dispersing aidInks, dyes Anti-blockFilms, coatings Anti-soilTextile, coatings Anti-statPlastics,fibers ReinforceRubber, foam. Effect Application