Avaliação da resistência ao desgaste por risco escleromético de PTFE com carga de oxicarbetos de metais de transição obtidos a partir da ciclagem térmica de rejeitos de scheelita

Abstract

The polymer PTFE (polytetrafluoroethylene) is characterized by measurementsof thefriction coefficients of 0,13 ±0,08, even in thermal and chemicaly hostile environments,but its wear rate is highest among the polymers. The aim of this study is toimprovetheir wear resistance by adding mineral filler of, obtained fromtailings of scheeliteavailable at the Mina Brejuí located at Currais Novos, RN. The oxycarbideswereproduced between 595ºC and 1000ºC during one hour, with a lower cost thantraditional chemical route, using the reactions involving solid state diffusionandphasetransformation. Were characterized by XRF, XRD, SEM, EDS. In cold pressingunderload 15.000 lbf (66,5 kN), were obtained 36 specimens of PTFEwiththreemassconcentrations, 15%, 25% e 35%. The deformation energy due to cuttingwasmeasured by means of a pendulum scratch testing. This scratch shownashapeofcircular sector on the plane surface of each specimen machined by a sharptool of anAISI 1045 quenched steel with a tip angle of 30º. The deformation energy dataset ispresented for each specimen and metallic oxycarbides concentrations. Theresultsofthe scratch resistance for the PTFE specimens without mineral filler as obtainedbySOUZA et al.(2013) were around a half in relation to those PTFE with 15%of mineral filler and this was 22% lower than the scratch resistance for specimen of PTFEwith25% or 35% of filler, suggesting a tendency towards a saturation at thislevel ofmineral filler concentration for the PTFE.