Análise tribológica do aço-cromo ASTM 52100 na presença de blendas diesel - etanol por meio de ensaios de fricção cíclica de alta frequência

Abstract

Due to the increase in diesel consumption in road transport and in several industrial segments, linked to the need to mitigate the environmental impacts caused by the use of fossil diesel, interest is growing in expanding the share of renewable fuels in the market. Thus, this work aims to analyze the behavior of fretting wear of ASTM 52100 chromium-steel in the presence of mixtures of commercial diesel (S500 and S10) with additions of commercial hydrated ethanol fuel (EHC) in percentages of 2%, 4.5% and 7% (v/v). The analyzes were carried out based on the ASTM G 133 standard (Standard Test Method for Linearly Reciprocating Ball-on-Flat Sliding Wear) using a pin-on-disc tribometer, type HFRR (High Frequency Reciprocating Rig), with an alumina pin as a counter-body, and ASTM 52100 chrome-steel discs as body, frequency of 50 Hz, applied load of 2, 5 and 8 N and sliding distances of 100, 300 and 500 m. Before testing, the samples were subjected to grinding and polishing to standardize the characteristics of flatness and surface roughness. Tangential forces and friction coefficients were obtained during the tests. Wear tracks were analyzed using optical microscopy to determine track dimensions and worn volumes, while scanning electron microscopy was used to identify associated wear mechanisms. This evaluation demonstrates that wear is directly related to the increase in applied load, according to the analysis carried out. It was observed that wear tends, with a weaker relationship, to increase with the increase in displacement and the increase in the percentage of ethanol.