FRICTION AND WEAR BEHAVIOR OF IRRADIATED POLYETHYLENE SLIDING AGAINST ROUGH STEEL SURFACE

W. TUCKART; E. MOLINARI; D. ROSSIT; M. FAILLA

TRIBOLOGY LETTERS

SPRINGER/PLENUM PUBLISHERS

Lugar: New York; Año: 2014 vol. 55 p. 165 - 176

1023-8883

The aim of this study was to evaluate the tribological behavior of polyethylene crosslinked by gamma radiation sliding against steel surface. Two high-density polyethylene´s were irradiated under vacuum at room temperature to total doses in the range from 2 to 20 Mrad. After irradiation, the materials were annealed at 423 K, and then cooled slowly to room temperature. The same treatment was applied to the non-irradiated polymer. The wear behavior of the polymers was determined under controlled ambient temperature of 298 K and 333 K using a homemade tribometer .  Sheet-shaped specimens were loaded against the surface of a steel disc with different normal loads to generate nominal contact pressures in the range of 0.25 to 1.5 MPa. The tests were performed under dry conditions using a disc rotation of 375 rpm during 30 minutes. The average sliding speed was of 1 m/s which gives a average sliding distance of 1884 m. The wear ratewas obtained as the mass loss of the sample divided by the sliding distance, and the friction coefficient was determined by measuring the force of friction. The results indicate that the wear rate increases with load in the case of non-irradiated polyethylene and low-dose irradiated polymers, while the wear rate reaches a maximum value with the load in the case of the irradiated samples with high dose. The samples irradiated with a dose of 10 Mrad showed the lowest wear. The coefficient of friction increases slightly with the load in all the cases. Most irradiated polymers shows higher coefficient of friction than the non-irradiated material when compared at a given load. It was not possible to determine a relationship between the coefficient of friction with dose.