Paper 13: Abrasive Wear of Journal Bearings by Particles in the Oil (Apparatus, Experiments, and Observations)

Abstract

Abrasion is generally defined as wear caused by fine solid particles. In this paper the term abrasion will refer only to wear caused by hard particles introduced into and entrained by a fluid flowing between two solid surfaces, the particles possibly becoming embedded in one of these surfaces. For the study of this type of wear a plain journal bearing was considered suitable. Arguments for this choice and a description of the apparatus are given. The use of an aerostatic bearing for the application of load to the plain journal bearing has made friction torque measurement feasible. The abrasives used were silicon carbide particles of very narrow size distributions; the carrier fluid was a mixture of a straight mineral oil and n-hexadecane. The wear of the shaft was determined by measuring its surface profile, the wear of the bush by measuring its deviation from roundness. Various combinations of materials were investigated. In most cases hardened steel shafts and soft bronze bushes were used. In addition, some plastic materials served for the bushes; steel, bronze, and aluminium were applied both as bush and as shaft material. Embedding of particles was observed at various places in the bushes, which were usually softer than the shaft. Additional information on the wear processes was obtained by microscopical inspection of the worn surfaces. Results of the experiments are discussed.