| Abstract: | An increase in reliability and a decrease in production cost of systems that include insulators require a better knowledge of the origins of friction, wear, adhesion, fracture and electric breakdown. By doing this, for example, a manufacturer could adapt his fabrication to the user's operational conditions whereas, at present, he only can offer a catalogue of standard specified products. The macroscopic behaviour of a material depends on the defects therein; these in turn determine the electric charge distribution and the internal energy of the material. Seen in this light, many pioneering results can be understood and used to clarify the experiments required for validating new theories of breakdown or wear. Several laboratories have worked together to demonstrate the direct relationships that exist between the microscopic parameters of charge and energy localization or relaxation and macroscopic behaviour. One essential point was to find how to carry out experiments whilst preserving the material's intrinsic defect state during sample preparation and how to characterize defects related to stresses applied to the material. Another point was to investigate the phenomena that occur at the early stage of wear, fracture and breakdown before catastrophic failure. Therefore the use of time‐ and spatially‐resolved measurements has been essential. This work reviews some pioneering results, pointing out the importance of polarization and conduction on apparently different behaviour (wear, adhesion and breakdown). These results have been explained from classical solid state physics and electrostatics backgrounds. When the experiments were carried out, however, characterization techniques for interpretating the results were missing, so that they did not receive the attention they deserved. Surprisingly, and as discussed in the second part, because these new characterization techniques have not been sufficiently disseminated in industry, these pioneering results and theories have not been practically applied. As a consequence, standard insulator specifications still do not reflect our actual knowledge. In the third part, some examples illustrate technological progress that can be made by combining some new characterization techniques with the standard ones. © 2001 Society of Chemical Industry |
