Tribological Behavior of Surfaces Obtained by Turning in Sintered Self-Lubricating Composites

Abstract

This work presents a study on the tribological behavior of surfaces obtained by turning in sintered self-lubricating composites. Turned surfaces were obtained at constant cutting speed (v_c = 100 m/min), feed (f = 0.2 mm), and depth of cut (a_p = 1 mm). The tested composites have solid lubricants (graphite and hexagonal boron nitride, h-BN) mixed in an Fe-C-Ni-Si matrix manufactured by single pressing (SP) and double pressing (DP). The turned and sintered surfaces were analyzed by scanning electron microscopy (SEM) and quantified by the roughness parameters S_q (root mean square height), S_sk (skewness), S_bi (bearing surface index), and S_tr (texture aspect ratio). The tribological tests were performed on turned and sintered surfaces with a cylinder–cylinder configuration. Raman spectroscopy and SEM were used to characterize the wear scars. Machining reduced the S_q parameter by 35 and 45% for the SP and DP materials, respectively, and the S_sk by 100%. The turned surfaces did not present friction coefficient values within the lubricity limit (µ < 0.2). The friction coefficient and the wear rate of the turned surfaces were around 320 and 40% higher, respectively, than those of the sintered surfaces.

Keywords:

• Self-lubricating composites
• machining
• scuffing resistance
• tribology
• wear

Additional information

Funding

The authors thank CNPQ, CAPES, and Embraco for funding this research. The authors also thank LABMAT, LCM, CERMAT, LMP of the Federal University of Santa Catarina.