Análise tribológica de compósitos à base de cBN e WC empregando como ligante um sinterizante inovador

Abstract

With the development of manufacturing processes, the metalworking industry is increasingly demanding advances, mainly in the modernization of machine tools and the constant evolution of cutting tools. In cutting tools, one of the main focuses is the materials used, where it is sought the reduction of energy consumption, better finishing of the final part and a longer tool life. The widely used WC composites, and the cBN, which has been studied since the end of the 20th century, has been continuously developing in order to optimize, as well as to improve physical-chemical and mechanical properties (hardness, fracture toughness) as a result of the most diverse materials to be machined. Within this scope, this work aims to study the wear of the composite tribological pairs WC - AISI 4140 and cBN - AISI 4140, for which the test with pin - on- disk configuration was used. WC or cBN, both composed by 90% of hard material + 10% of binder being this binder, composed of 90% Nb + 10% Ni and as disk AISI 4140 steel subjected to different thermal treatments, being: annealing, tempering, quenching. In order to analyze the results obtained in these tests, the dynamical friction, wear rate, temperature close to the counted region, as well as elastic energy of vibration of the structure were measured through installed sensors. Aiming to characterize the surface of the tribological pair prior to the test, measurements of hardness and roughness were performed in the contact region. After the tests, wear "trail" analyzes were performed on SEM, EDS, DRX. The tribological analysis performed in this work showed the efficiency of the composites tested. It was verified that the mechanism of failure by loosening of the less sintered cBN grains and subsequent encrustation of these particles on the metal matrix under the cBN-R and cBN-TR assay conditions, cBN as a cutting tool for materials with a hardness of less than 40 HRC.