Sol-gel is a chemical route to the manufacture of ceramics and inorganic-organic hybrid materials.
The sol-gel process involves creating a ‘sol,’ which is a colloidal suspension of solid particles in a liquid. This sol is then transformed into a three-dimensional gel network that traps the liquid, before being dried to remove the liquid and aged to improve the structural integrity. Once dried, the gel is heat-treated at high temperatures (by curing or firing) to create a dense, solid, cross-linked film or material. This final material can be a ceramic, hybrid inorganic/organic compound, or a glass.
This versatile process can synthesise a range of materials that can be used for high-value coatings, chemical sensors, optical devices and biomedical applications. These materials offer different properties according to their application.
Sol-Gel Applications
- Coatings: Sol-gel technology is a leading method for the production of coatings that provide chemical and mechanical protection (against corrosion and wear), specific optical or electronic properties, and catalytic solutions.
- Functional Materials: Sol-gel can also be used to produce fine abrasive particles, optical fibres, chemical and biological sensors, and biomaterials for use in the medical profession.
Sol-Gel Advantages
Sol-gel provides higher levels of purity when creating oxide glasses and ceramics when compared to normal processing methods. This is because the raw materials used in sol-gel are manufactured from highly purified components. Although this is not necessary for many applications, some specialised sectors - including displays, semi-conductors and the nuclear industry - require very low levels of certain impurities.
Because sol-gel allows for organic components to be incorporated into the ceramic network, the process can be used to improve adhesion, increase water repellency or to allow a ceramic to be more readily incorporated in organic formulations for coatings, adhesives, inks or paints. Organic / inorganic hybrids can be added to adhesives, bulk polymers or coatings to enhance material properties so as to provide improved abrasion resistance, increased solvent resistance, and better barrier properties. Each of these properties can be tailored to meet the specific demands of a particular application.