Efeito da adição de bissulfeto de molibdênio (MoS2) na resistência ao riscamento da poliamida 6.6/6

Abstract

Mining companies face challenges related to transportation modals and logistics to distribute all their production. The use of continuous transportation systems offers advantages ranging from lower transportation costs, potentially reducing diesel consumption by up to 70% compared to truck usage, to reduced noise pollution. The carrying roller bodies that compose belt conveyors are typically made of carbon steel. For some applications, there are also rollers made with aluminum tubes and polymer tubes, which are lighter. The Laboratório de Superfícies e Contato (LASC) at the Universidade Tecnológica Federal do Paraná (UTFPR), Curitiba campus, in partnership with the mining company VALE S.A., has been conducting studies since 2018 on the technical feasibility of replacing metallic rollers with polymeric ones. Polymers already commercially used in roller manufacturing are being studied, along with the possibility of developing new polymer composites. In the studies conducted só far, the performance of polyamide 6 in abrasive tests and its classification according to UL-94 standard allowed the decision to proceed with studies related to abrasion resistance, the focus of this research. Among the polyamides available in the catalog of the supplier company for conveyor belt rollers is polyamide 6.6/6. This study evaluated the the possibility of applying “pure” polyamide 6.6/6 and polyamide 6.6/6 with 1.5% molybdenum disulfide for the manufacture of rollers used in ore conveyors. Sample characterization was performed through TGA, FTIR, DSC analyses, and Shore D hardness measurement. Scratch tests were conducted using conical penetrators, applying preload from 5 N to 20 N, scratch load from 20 N to 40 N, and scratch velocity of 5.1 mm/min. Single and multiple pass tests were conducted. Images of scratched surfaces were generated using scanning electron microscopy to analyze wear generated by scratching. The width and depth of the grooves at their final region were measured using 2D profilometry. The addition of 1.5% molybdenum disulfide to PA6.6/6 brought advantages regarding the apparent coefficient of friction. The penetrator geometry influenced the values of the apparent coefficient of friction and the width and depth of the grooves. Plastic deformation occurred in all tests, as well as the formation of pile-up, prow, and material removal.