Estudo tribológico dos revestimentos de Fe-29Cr-4B-1,75Si E WC- 10Co-4Cr por aspersão térmica para redução do desgaste abrasivo e erosivo resultante da ação do grão de arroz

Abstract

Rice production is the third largest in the world out of six thousand species of cereals being behind only corn and wheat. Components of machines that work under direct contact with rice grain suffer severe wear due to the abrasive nature of their husk. Thus, the main objective of this study is to investigate the tribological behavior of the Fe-29Cr-4B-1.75Si coating sprayed by the electric arc with wire method and the WC-10Co-4Cr coating sprayed by the high velocity oxygen fuel - HVOF, both on SAE 1016 carbon steel substrate. The abrasive wear test was performed using ASTM G65 standard which uses sand as an abrasive and a variation employing the rice husk as an abrasive material. Furthermore, the in situ tribological behavior of the coatings in a rice drying structure with processing capacity of 70 t/h was investigated. The coatings were characterized by scanning electron microscopy (SEM), X-ray diffraction and microhardness. As a main result it was noticed that the coating with higher microhardness (WC-10Co-4Cr) showed the lowest wear rates during the tests. Analyzing the wear mechanisms under the coatings and substrate when using the sand as an abrasive material (ASTM G65 test), the material was removed by scratches while using the rice husk the mechanism of wear occurred by micro cuts. Another important point was the fact that the samples suffered a high loss of volume due to erosive wear when subjected to wear inside the rice drying structure, in situ.