Polyesterimide composites as a sensor material for sliding bearings

The piezoresistive polyesterimide composites, with high wear resistance and low friction coefficient were developed and described in this paper. The composites were used in mechanical systems as a bearing material, deposited on the surface of sliding bearing and as a sensor, which can monitor of bearing condition. Composites consist of polyesterimide matrix, electrical conductor powders and lubricating additives. A short review of the background for understanding the electrical transport in such materials is given. A theoretical model for calculation of tribological system resistance has been derived. The results of experiments exhibit good sliding properties and high wear resistance of the composites and a unique feature, i.e. electrical resistivity of bearing material depends on the applied load and temperature. By comparing theoretical calculations with experimental measurements it has been shown that the model for diagnostic system can predict the system resistance with reasonable accuracy.