Microestrutura, propriedades mecânicas e tribológicas de metal patente depositado por aspersão térmica

Abstract

Sliding bearings are mechanical elements which hold considerably large importance, for their use on many branches of industry. These elements operate via interaction between Babbitt metals, deposited on the inner surface, with the rotating axle. Babbitt metals are basically tin or lead-based alloys, which convey the applicational advantages of low friction coefficient, high ductility, and good toughness, that during the operation, absorb the energy generated by the axle bearing, as well as the shock waves resultant of the system fluctuations, giving the system longer lifespan and reliability. This work will make the characterization of a Babbitt metal alloy deposited by different thermal spray processes, comparing the same alloy deposited by conventional methods, with the goal of evaluating how the resulting microstructure and mechanical properties of the deposition processes will be affected by the different thermal spraying methods. The chemical composition of the coatings and the micro hardness will also be evaluated. Additionally, factors such as adherence and tribological behavior of the coatings will be analyzed. Thus allowing us to compare the microstructures, mechanical and tribological properties with the conventional coatings methods. It was observed that the thermal spray processes resulted in coatings with lower precipitate formation than conventional methods, however with a higher formation of CuSn precipitates, as a function of the temperature and the cooling rates achieved, which increases the bond strength without changing hardness. The tribological behavior of the coatings obtained by thermal spraying showed lower wear level, but the coefficient of friction observed is higher, compared with the Babbit alloy deposited by conventional process. It was observed that coefficient of friction was more stable and less dispersion throughout the tribological test, which greater dynamic stability to the coating for sleeve.