Sol-gel technology is a synthesis method for solid materials using a liquid at low temperatures, allowing for the controlled formation of nanoparticles. The process involves hydrolysis, condensation, gelation, and drying, influenced by factors such as the water to alkoxide ratio and the type of catalyst. Applications range from optical and biomedical uses to electronic and thermal applications, while advantages include the production of high-purity materials and complex shapes, although it has limitations like weak bonding and high permeability.

1. SOL-GEL
TECHNOLOGY
Guide: Presentedby:
Dr. R C Sastry SruthiR
Professor,Dept.ofChemicalEngg, M.Tech:-156512
NITWarangal 2015-16

2. Contents…
Introduction
Sol andGel
Sol gelprocess
Factors influencing sol-gelprocess
Applications
Advantages
Limitations
Future
Reference

3. Introduction…
• Sol –gel processing designates a type of solid material synthesis ,performedin a
liquid and at low temperature.
• Dissolve the component in a liquid inorder to bring itback as a solid in a controlled
manner.
• It’sa typical nanotechnology because all gel products contain nanoparticles or are
nanocomposites.
• Synthesis schemes used depends on initial precursors.

4. Sol &Gel…
Sol is a stable dispersion of colloidalparticles or polymers in a solvent.
Consist of liquid with colloidalparticles which are no dissolved, but do not
agglomerate orsediment.
Gel is a three dimensional continous network which encloses liquid phase.

5. Aerosol
Suspension of fine solid particles or liquid droplets in a gas.
Aerogel
Drying is performed at super critical conditions, network structure may be retained and a
gel with large pores may be found.
Xero gel
Gel is dried by evaporation ,capillary forces will result in shrinkage, the gel network
collapse.

6. Xero gel
Aerogel

7. Sol-Gel Process…

8. Steps involved are…
 Hydrolysis and condensation of molecule
 Gelation
 Ageing
 Drying
 Firing
 Densification

9. Factors Influencing Sol-Gel Process…
 Parameters influencinghydrolysis
Water toalkoxide ratio
Type and amount of catalyst
 Parameters influencingcondensation
Type ofprecursor
Alkoxide waterratio
Type ofcatalyst
pH
Type ofsolvent

10. Applications ofSol-GelTechnology
Optical and photonicapplications
Mechanical applications
Biomedical application
Bioreactors
ChemicalApplications
Electronicapplications
Thermal applications

11. Advantages…
 Can produce thin bond-coating to provide excellent adhesion between the metallic
substrate andthe top
 Can produce thick coating to provide corrosion protection performance.Can easily
shape materials into complex geometries in a gel state.
 Can produce high purity products because the organo-metallic precursor of the desired
ceramic oxides can be mixed, dissolved in a specified solvent and hydrolyzed into a sol,
and subsequently a gel, the composition can be highly controllable.
 Can have low temperature sintering capability, usually 200-600°C.
 Can provide a simple, economic and effective method to produce high quality coatings.
 Through sol-gel processing, homogeneous, high-purity inorganic oxide glasses can be
made at ambient temperatures rather than at the very high temperatures required for
conventional formation of glasses.

12. Limitations…
Weak bonding
Low wear-resistance
High permeability
Difficulty incontrolling
porosity
Substrate dependency

13. Future… .
Researches are progressingin
Organically modified Sol-Gel sensors
Biomolecules from Sol-Gel matrix
Bioactive nano-coatings for future medicines