Dual Tribological Behavior of a Nanolayered Ceramic: Ti3SiC2

Abstract

AbstractThe MAX phases are new, thermodynamically stable, nanolayered ternary carbides and nitrides. These materials have a big potential in tribological applications due to their structure, similar to graphite or molybdenum disulfide. For example, the friction coefficients of the basal planes of Ti3SiC2 have been shown to exhibit very low (<; 5 × 10-3) friction coefficients. The aim of this study is to better understand the tribological behavior of polycrystalline Ti3SiC2 against stainless steel. Experiments were conducted on a ball-on-flat tribometer (∼ 25°C and ∼ 30% relative humidity) that simultaneously measures friction coefficients and electrical contact resistance. Different stainless steel ball diameters and normal loads were used and resulted in contact pressures between 0.35 and 1.25 GPa. Two different tribological behaviors were observed, both with relatively low friction coefficients for ceramics. The first behavior, referred to as type I, is characterized by low friction coefficients (≍ 0.15); low wear and a transfer film containing titanium and carbon formed on the ball. The other behavior, type II, is characterized by friction coefficients that starts at ≍ 0.15, and then increases to about 0.4. At the end of the experiment, the ball is worn, and compacted wear debris containing iron can be found on the plane. The two behaviors seem to be independent of contact pressure, but are rather sensitive to normal applied load. The transition between these two regimes will be discussed.