Study of the tribological behavior of the Babbitt alloy – steel ABNT 1045 pair when varied thickness and roughness of the coating

ABSTRACT Babbitt, also known as patent metal or white metal, is a soft alloy widely used in sliding bearings that work in contact with steel, and has as base elements tin or lead, as well as intermetallic compounds usually formed by antimony and copper. The aim of this work was to evaluate the influence of the parameters roughness and thickness of the coating on the tribological behavior of the alloy when in contact with steel ABNT 1045. Tribological pin-on-disk tests were performed using ABNT 1045 steel pins and Babbitt-coated steel test specimens simulating the contact of a shaft on a Babbitt-coated bearing. The roughness and the thickness of the coating were varied in three levels, in order to observe the behavior in relation to the friction and the wear with the modification of these variables. In the tests that used test specimens with the smallest roughness within the analyzed range, an increase of 0.05 ± 0.02 to 0.46 ± 0.06 in the friction coefficient occurred when the coating thickness was raised from 0.45 ± 0.07 mm for 1.08 ± 0.17 mm. The highest coefficient of friction was observed in the test of the specimen with a higher coating thickness (1.08 ± 0.17 mm) and lower roughness (0.47 ± 0.01 μm), the highest wear was recorded in the test with the highest coating thickness and roughness (1.08 ± 0.17 mm and 1.29 ± 0.20 mm, respectively) and the lowest wear and friction coefficient were obtained by the test performed in the specimen with the least roughness (0.43 ± 0.03 μm) and medium coating thickness (0.45 ± 0.07 mm).