Experimental Study of the Applicability of a Fluoroplastic-Graphlex Composite as an Antifriction Material for Water-Operating Sliding Bearings

Abstract

A comparative study of the antifriction characteristics of a composite material based on fluoroplastic-graphlex composite and PTFE (F-4 in Russian nomenclature) was carried out under a wide range of test conditions, including both “segment – disk” friction tests and radial sliding bearings. The tests were carried out at various loads, rotational velocities and temperatures, as well as in “dry” and “wet” friction modes. Although in “segment – disk” friction pair testing an approximately equal friction coefficient was observed for the fluoroplastic-graphlex composite and PTFE, the mass wear of fluoroplastic-graphlex was almost 500 times lower than that for PTFE. In addition, the supply of water to the friction surface was shown to result in stabilization of the surface temperature of the friction pair and a decrease in the friction coefficient. The fluoroplastic-graphlex composite exhibited a good conformability to a steel surface (without scoring or lamination) and high wear resistance at specific loads of 1 – 6 MPa. In a comparative test of sliding bearings based on the fluoroplastic-graphlex composite and PTFE for the 0.5 – 2.0 MPa specific load range, the values of the shaft circumferential velocities are determined to provide ideal hydrodynamic lubrication formed in water-operating radial sliding bearings. Moreover, a slight heating of the fluoroplastic-graphlex composite material (6°C) was detected in the initial temperature range of 35 – 60°C. The experimentally established value of the water flow rate through the bearing of 0.1 liters/sec is practically independent of shaft rotation frequency and applied load. Moreover, a good conformability of the fluoroplastic-graphlex material was confirmed by the clean friction surface, having a polished appearance and no observable scoring, cracking, or chipping of the composite material.