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Maskless electrochemical texturing (MECT) is an inexpensive and fast technique with great potential to produce surface textures on metallic surfaces at industrial scale. This work used MECT to produce arrays of chevrons onto AISI 1045 steel surfaces. Block-on-ring tests using standard rings and textured blocks investigated the effects of full and partial texturing on friction and wear. Two normal loads (216.9N and 315.0N) were applied to investigate the effects of the textures under mixed and boundary lubrication regimes. Under the lower load, MECT increased friction and wear rates. This was attributed to the surface roughening of the areas outside the chevrons, which reduced the ratio between the average roughness of the asperities and the hydrodynamic film thickness (λ ratios), shifting the lubricant regime from mixed to boundary lubrication. Partial texturing performed better than full texturing, but no clear trend was found for the position of the textured potion either at the inlet or the outlet of the contact. On the other hand, for the higher normal load, both smooth and textured samples operated under boundary lubrication, so that the effect of the pockets to supply additional lubricant to the contact resulted in reduced friction and wear. Entrapment of wear debris within the chevrons was found for both normal loads, which avoids the presence of hard debris in the contact, thus also contributing to reduce friction and wear. The Kruskal-Wallis test was applied, and it was observed that the factors, load and surface, produced statistically significant effects on friction coefficient values.

This work presents a methodology used to filter the roughness profile of soft metals and natural materials. This methodology is based on polynomial regression, Robust Gaussian Regression filter (RGRF) and Abbot filter. The advantages of this method come from the possibility of elimination the deep valleys introduced by scratches after manufacturing or associated with anatomy of materials like wood. The method involves three steps: i) fitting roughness raw data with polynomial regression to remove profile form errors; ii) using the RGRF to filter the profile waviness; iii) applying the Abbot curve method to remove the remained deep valleys. The resulting profile was used to determine roughness parameters Ra and Rmax. Samples of wood Eucalyptus Camaldulensis and aluminium were prepared to carry out the measurements and the calculations where performed with algorithms developed using MatLab software. The results proved that the proposed approach is robust against modifications introduced after processing of soft materials surface and suitable to apply to materials having particular anatomic components. Keywords: roughness, filtering, polynomial regression, RGRF, Abbot curve. RESUMOEste trabalho apresenta uma metodologia para filtrar o perfil efetivo na medição da rugosidade superficial de metais moles e materiais naturais, baseado na aplicação de regressão polinomial, regressão gaussiana robusta (RGRF) e curva de filtragem de Abbot. A vantagem deste método reside na possibilidade de remover os vales profundos introduzidos após a fabricação ou associados à anatomia de materiais como madeiras. O método deve ser aplicado em três etapas sequenciais: ajustar os dados do perfil efetivo a uma regressão polinomial para remover o erro de forma; ajustar este novo perfil a uma regressão RGRF para filtrar a ondulação; aplicar a curva de filtragem Abbot para remover os vales profundos remanescentes. O perfil resultante foi usado para determinar os parâmetros de rugosidade Ra e Rmax. Amostras de madeira Eucalyptus Camaldulensis e alumínio foram preparadas para executar as medições e os cálculos foram feitos através de algorítmos desenvolvidos no programa MatLab. Os resultados mostraram que a abordagem proposta foi robusta em relação às modificações introduzidas após o processamente de materiais moles e adequada para aplicação em materiais com componentes anatômicos destacados. Palavras-chave: rugosidade, filtros, regressão polinomial, RGRF, curva de Abbot.

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