Desgate microabrasivo e evolução microestrutural de ferro fundido cinzento com adição de nióbio aplicado em dois discos de freios automotivos

Abstract

Gray cast iron has as main characteristics low manufacturing cost, good machinability, and good thermal conductivity. These characteristics allow its use on a large scale in the industry, among them, in the production of brake discs, which is an automotive brake systems component. Continuous developments in friction materials are directly related to studies of the tribological pairs of brake systems, which are brake pads and discs and brake linings and drum. The main objective was to evaluate the influence of different niobium contents on the microstructure, mechanical properties and microabrasive wear resistance of gray cast irons applied to automotive brake discs. Thus, this work evaluated the microstructure through metallographic investigations, mechanical properties (hardness, toughness and tensile strength) and tribological properties (microabrasive wear resistance) of gray cast iron with the addition of different niobium contents. It was observed that the addition of niobium in the gray cast iron alloy changed the morphology of the graphite flake and also the spacing of the pearlitic matrix. The results of mechanical properties did not show significant changes, however, the microabrasive wear resistance of the material increased with the addition of niobium. [resumo fornecido pelo autor]