TWI Industrial Member Report Summary 835/2005
By A Gunner
Sol-gel processing is a method for preparing ceramic materials from solution. This offers several benefits including low processing temperatures compared with traditional sintering routes. Sol-gel methods may be used to prepare ceramics in many forms, including nanoparticles, monolithic components and fibres. It is their potential for the preparation of coatings which is the focus of this work.
A coating prepared by sol-gel processing will generally have comparable properties to the bulk material on which it is based. Thus, by selecting appropriate materials, a coating can be deposited which may be tailored to be hard, corrosion resistant, semiconducting or have many of the other properties associated with ceramics.
Sol-gel work to date at TWI has concentrated primarily on transparent hard coatings to provide cosmetic protection for consumer applications. Therefore the significant parameters have been transparency, colourlessness and scuff resistance, together with ultra-violet (UV) light and water stability. This work has culminated in the patenting of Vitresyn®, a nanocomposite inorganic/organic hybrid material.
For other applications however, different parameters are more significant. A previous project investigated the use of sol-gel coatings for corrosion protection under ambient conditions. This project has extended the work, benchmarking TWI's generic coating types and assessing their suitability for operation at elevated temperature.
This report describes a method of determining the conditions to achieve full cure of a range of sol-gel derived coatings, and their upper temperature capability. Additionally, an initial evaluation of one material property, surface energy, has been undertaken, with a view to identifying anti-fouling properties of industrial relevance.
- Review high temperature coating application requirements.
- Identify suitable schedules for full curing of a range of silica based sol-gel coatings.
- Determine operational temperature limits for silica based sol-gel coatings.
- Determine whether the coatings have potential for use in anti-fouling applications.