Tribological behavior of Al 6061 and Ti6Al4V alloys against lunar regolith simulants at extreme temperatures

Abstract

Spacecraft landings on Earth's moon are highly susceptible to lunar regolith particle impingement leading to abrasion and premature failure of structural components. Herein, abrasive wear of Al 6061 and Ti6Al4V, critical aerospace alloys in two lunar simulants environments viz. JSC-1A and Greenland Anorthosite (GA) under extreme temperature conditions were examined. The highest wear loss was observed for softer Al 6061 without simulant conditions at all temperature ranges, while harder Ti6Al4V has the highest wear loss when sliding with JSC-1A. Wear loss increased under high temperature (HT) conditions due to thermal softening in alloys. The synergy of material removal and addition in three-body wear showed that wear volume quantification via the conventional method is improbable. A novel technique to quantify “true wear volume” incorporating embedding fraction (Ef) is developed. The results showed that JSC-1A regolith, owing to sharper morphology than GA, creates more embedding at RT and HT by 12% and 15% on Al 6061 and 23% and 29% on Ti6Al4V. A non-dimensional embedding index (Ei) is postulated, which can potentially serve as a tool to establish abrasion caused by lunar dust for future explorations.