Effects of temperature on friction and degradation of dry film lubricants during sliding against aluminum alloy sheets

Hotmelts are nowadays widely used as dry film lubricants (DFL) in aluminum sheet forming. However, their chemical composition and the degradation of functional additives during the forming process are rarely reported. The present work investigates the chemical composition of three hotmelts deposited on aluminum alloy sheets with electrical discharge-textured (EDT) and mill-finished (MF) surfaces using mass spectrometry (MS), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). The surface topographies and the tribological conditions were investigated at temperatures between room temperature and 100 degrees C using single-pass sliding experiments. The results show considerable change of the tribological conditions due to reduction of friction modifiers and antiwear additives during sliding particularly at 100 degrees C.