Avaliação experimental do atrito em corpos conformes texturizados visando otimização tribológica em mancais de usinas hidrelétricas

Abstract

Regarding the problem of energy and material consumption in hydroelectric plant bearings, the hypothesis was raised to investigate methods of manufacturing topographic patterns on cylindrical surfaces using electrochemical machining. In addition to the search for an ideal methodology, this present work questioned the advantages of using textures with simple geometry, formed by circular pockets, and composed of circles and ellipses. The investigation took place considering the three lubrication regimes in conformal contacts: boundary, mixed and hydrodynamic. The system efficiency was evaluated in terms of friction coefficient for ABNT 1045 steel samples submitted to block-on-ring wear tests. The friction coefficient data pointed to reductions in the order of 52% for simple textures and 31% for composite textures, considering the borderline lubrication regime compared to non-textured samples. For the hydrodynamic regime, samples with composite textures showed reductions of 9% in the friction coefficient, while simple textures showed decreases of up to 36% considering the boundary lubrication regime compared to unmachined samples. The samples without topographical change, operating in the mixed lubrication regime, presented values of friction coefficient 74% higher, compared to samples with composite textures and up to 85% higher for samples with single geometry texture. The set of information shown by this work, corroborated by similar wear mechanisms between the samples and the cases in the field, infers potential application of the deterministic texturing technique in bearings used in power generation systems.