Formation of transfer layer and its effect on friction and wear of carbon-graphite face seal under dry, water and steam environments

The present work aims to explore the friction and wear characteristics of antimony-impregnated-carbon-graphite material used in steam rotary joint and to study the transfer of graphite films from seals to mating metal surfaces. An experimental facility consisting of a 1.3 MPa capacity boiler to supply saturated steam, a torque sensor, a displacement sensor, two thermocouples, a data acquisition system, a bakelite coupling to insulate the torque sensor, a 2237 W (3 hp) A.C. motor with frequency drive to control the rotational speed of shafts, and actual rotary joint has been developed to measure the instant friction losses and calculate the wear loss of four seals used in rotary joint. Wear loss, friction torque and surface temperature of sealing surfaces have been measured under dry, water and steam lubrication conditions. The obtained results are tabulated and plotted for quick understanding of experimental findings. Discussions on the excessive wear rate due to the presence of abundant water, misalignment and closing force are presented. Finally design changes to enhance the seal life are recommended.