Investigations on the temperature-dependent tribological behaviour of spark plasma sintered CNT-304 SS self-lubricating nanocomposites

Abstract

ABSTRACT Herein, we report the tribological behaviour of CNT-304 stainless steel composites at room (28°C) and high temperatures (200°C). Nanocomposites of various CNT concentrations, namely 0.2, 0.5, 1.0, 2.0, 3.0, and 4.0 wt%, were prepared. A significant amount of grain refinement resulted in an increase in CNT loading. A tribological study was carried out at 28°C and 200°C. Wear resistance was found to enhance with an increase in CNT concentration at both temperatures. However, a slightly higher wear rate was observed at 200°C for the samples with CNT content < 3 wt% than their corresponding low-temperature values. About 86%, 91% drop-in wear rate was seen in 2.0 wt% CNT-304 SS, and 4.0 wt% CNT-304SS, respectively, as compared to pure SS at 28°C, which is 54% and 88% decrease at 200°C and is very promising. The decrease in wear volume with CNT content at both temperatures can be ascribed to the self-lubricating and reinforcing nature of CNTs in the metal matrix composites. Severe abrasive wear in the pristine SS samples was slowly changed to mild abrasive and lubricated wear in composites. A systematic study on the tribological behaviour of CNT-SS composites can shed light on the benefits and detriments of using them for various applications. Highlights Incorporation of CNTs into 304 SS matrix caused grain refinement. Wear rate decreased with CNT content and 4.0 wt% CNT-SS showed minimum wear rate while pristine gave the maximum at both 28°C and 200°C. About 86% and 54% decrease in wear rate were observed for 2.0 wt% CNT-304 SS at 28°C and 200°C respectively as compared to the pristine 304 SS sample. Wear rate at 200°C was slightly more than that of room temperature (28°C) for CNT content < 3 wt%. The 3.0 wt% CNT-304 SS and 4.0 wt% CNT-304 SS showed nearly the same wear rate at both ambient and 200°C test.