TWI Industrial Member Report Summary 631/1998
A Taylor and J A Fernie
Sol-gel is an emergent technology for the fabrication of glasses, ceramics and a new class of polymer/ceramic composite materials (ormocers).
Background
Industry is constantly placing ever greater demands on the materials it uses. In general it is true to say that industry wants materials with superior properties which display greater reliability and at lower cost. Historically, such improvements have largely been delivered through incremental advances, such as slight changes in composition or enhanced control during processing. Increasingly, however, existing materials are being asked to operate at, or very near, the limits of their capabilities. Whilst there is undoubtedly room for improvement in the short term, longer term predictions indicate that more radical changes are required if industry's demands for the next century are to be met.
For many applications, successful implementation is being frustrated by an inability to achieve adequate properties and/or a high enough degree of reliability using current processing technologies.
One reason for these difficulties is that many fabrication processes are adaptations of techniques originally developed for different types or forms of material. There is therefore currently considerable pressure from industry to develop new processing routes which are not only more economic than existing techniques, but are also capable of yielding the desired performance characteristics from advanced materials.
Sol-gel offers an exciting new possibility for glass and ceramic fabrication. It is a liquid phase route, involving chemical processing, but has the simplicity in the processing of product forms. It also starts with pure materials, so the final product can be of high purity or can be tailored for a specific application. A further attraction is the ability to build up composite materials, based on polymers and glasses/ceramics, with novel properties. In summary, sol-gel can fabricate:
Materials
- very high purity materials
- novel materials (including polymer/ceramic hybrid materials)
- materials with closely controlled, compositions
Product forms
- thin inorganic films
- uniform powders
- very porous materials (in excess of 90% porosity by volume)
Objectives
- To review the current status of sol-gel technology in terms of processing routes and product forms
- To outline the current and potential industrial uses for sol-gel derived materials