If low concentrations of solids are present (less than 2%) and their size is relatively small (0.003â€), hardened bearings running against a hardened journals provide excellent results in long term operation and service life. The hard bearings and journals allow the solids to pass through the pump without causing damage.
Typical bearing materials are silicon carbide, tungsten carbide or aluminum oxide. The journal area of the shaft or a shaft sleeve is usually constructed of stellite, tungsten carbide or silicon carbide. Due to the differences in the coefficients of expansion of the hardened bearings and journals, pumps featuring hardened materials should not be run dry for any length of time.