TY - JOUR A1 - Pontes Rodrigues, A. C. A1 - Nunes Ribeiro, P. J. A1 - Österle, Werner A1 - de Farias Azevedo, C. R. T1 - Failure analysis as a tool to optimize the design of a ring on disc tribotest investigating the role of surface roughness T2 - Engineering failure analysis N2 - The influence of the surface roughness of pearlitic grey cast iron discs on the formation of tribofilms and the evolution of the friction coefficient during a ring on disc tribotest with the addition of magnetite and magnetite–graphite nanopowders as interfacial media was investigated. The roughness parameters of the cast iron discs were varied by electro discharge machining (EDM) and grinding processes, producing four distinct surface roughness conditions. The evolution of the friction coefficient, however, did not reach the steady state for most of the samples and the role of the surface roughness on the friction coefficient could not be identified. Focused ion beam (FIB) microscopy on the cast iron discs was carried out to investigate the microstructure of the discs near the tribosurface. These results showed that the EDM process not only varied the surface roughness, but also changed the microstructure of the cast iron discs, promoting the incipient fusion of the cast iron surface, with the formation of ridges and casting defects (pores). As a result, a layer of rapidly solidified metal with a dendritic microstructure was formed near to the surface of the EDMed discs. PB - Elsevier Science Publ. CY - Oxford KW - Ring-on disc tribotest KW - Surface roughness KW - EDM-processing KW - Rapid solification PY - 2015 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/34623 AN - OPUS4-34623 SN - 1350-6307 SN - 1873-1961 VL - 56 SP - 131 EP - 141 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany