Comportamento tribológico do par polimérico polipropileno e poliamida em diversas condições de lubrificação

Abstract

The objective of this work is the tribological study of the polypropylene and polyamide 6 polymer pair in environments lubricated with distilled water, synthetic and non -lubricated sea water, varying the normal load and the average slip speed.The tribological test was performed in a tribometer in the alternating pin-plane configuration in conformal contact. For the conditions lubricated with distilled water and synthetic sea water three normal loads and one slip speed were used, whereas in the non-lubricated condition a load and three different speeds were maintained, each condition counts on five repetitions, totaling 45 essay.The distance covered during the test ranged from 108 to 540 m. During the tests the temperature of the lubricants, the surface temperature of thepolyamide sample 6 (non-lubricated condition), friction force and relative humidity were monitored for further analysis. For the calculation of the wear rate, the loss of mass of the samples before and after the tests was measured.In the case of polymeric materials that have sensitivity to temperature and the presence of moisture, a specific methodology was developed for these materials in order to be able to measure their mass. The behavior of the friction and the wear was performed through the analysis of the data obtained in the tribometer by the optical microscope and scanning electron microscopy -this was used to identify the wear micromechanisms, which were, in general, surface fatigue (micro-cracking), abrasion, film transfer, wear by roll formation and meltingwear.It was observed that, for the load variation, no wear severity transition was found, and the wear rates for the conditions lubricated with distilled water and synthetic sea water did not present a significant difference for polypropylene. However, in the non-lubricated condition, the transition from mild to severe wear to polypropylene was found. The wear rate of polyamide 6 was measured, in spite of the high hygroscopicity of the material, but showed a high dispersion of the data, and it was not possible to identify the difference between the wear rates for the three conditions