Wear evaluation of resin composite carbon graphite bearings for canned motor pump in dry environments

Abstract As carbon neutrality becomes more important, submersible pump bearings are required high sliding properties and long service life in the chemical industry for decarbonizing. In this study, we conducted the sliding bearing tests using carbon graphite bearings containing resin material and five types of the stainless-steel shaft sleeves with surface treatments, in a dry environment assuming the pump start up and the cavitation occurrence. In addition, we evaluated the surface roughness and amounts of wear of carbon graphite bearings. When the value of PV (Pressure×Velocity) was 5.24 kg/cm 2 ∙m/s in the pair of the resin composite carbon graphite bearing and the shaft sleeve coated Stellite, the motor shaft rotation continued the operation for 30 minutes. On the other hand, the motor shaft rotation of the other pairs stopped within 10 minutes due to seizure on the friction surfaces over 170 ˚C. As a result of the use of Stellite as the surface treatment, the self-lubricating film by carbon graphite formed on the whole friction surface of the shaft sleeve. This self-lubricating film formation helped reduce friction between the resin composite carbon graphite bearing and the shaft sleeve, which lowered the operation temperature.