X-ray photoelectron spectroscopy study of the stability of Fomblin Z25 on the native oxide of aluminum

Abstract

Thin films of Fomblin Z25, a perfluoropolyalkylether lubricant, were vapor deposited onto clean, oxidized aluminum, and sapphire surfaces, and their behavior at different temperatures was studied using x-ray photoelectron spectroscopy and temperature desorption spectroscopy (TDS). It was found that the interfacial fluid molecules decompose on the native oxide at room temperature, and continue to decompose at elevated temperatures, as previous studies had shown to occur on the clean metal. TDS indicated that different degradation mechanisms were operative for clean and oxidized aluminum. On sapphire substrates, no reaction was observed at room temperature. Our conclusion is that the native oxide of aluminum is neither passive nor protective towards Fomblin Z25. At higher temperatures (150 °C) degradation of the polymer on sapphire produced a debris layer at the interface with a chemical composition similar to the one formed on aluminum oxide. Rubbing a Fomblin film on a single crystal sapphire also induced the decomposition of the lubricant in contact with the interface and the formation of a debris layer.

Room Temperature Halide‐Eutectic Solid Electrolytes with Viscous Feature and Ultrahigh Ionic Conductivity

“…[ 32 ] The peak positions of F 1 s at 685.9 and 687.2 eV are respectively attributed to the presence of LiF and AlF 3 in the composite. [ 33 ] For the Al 2 p spectrum, the peak appears at 76.8 eV which is attributed to AlF 3 . [ 34 ] These results confirm that the deep eutectic reaction forms a halide composite with LiCl, LiF, AlF 3 , and Ga–Cl compounds.…”

Metastable nanostructured metallized fluoropolymer composites for energetics

“…21 While PFPEs are stable in an inert atmosphere up to 410 C and to approximately 316 C in an oxygen-rich environment, they are catalytically decomposed by metals and Lewis acids at lower temperatures. [22][23][24] Ab initio calculations of peruorodiethylether ((CF 3 CF 2 ) 2 O) as model systems to PFPEs concluded that protonation via Lewis acids at all sites (uorine and oxygen atoms) is energetically favorable.…”

“…21 While PFPEs are stable in an inert atmosphere up to 410 C and to approximately 316 C in an oxygen-rich environment, they are catalytically decomposed by metals and Lewis acids at lower temperatures. [22][23][24] Ab initio calculations of peruorodiethylether ((CF 3 CF 2 ) 2 O) as model systems to PFPEs concluded that protonation via Lewis acids at all sites (uorine and oxygen atoms) is energetically favorable. 25 Therefore, it is probable that decomposition is not totally due solely to acid-mediated reactions with the polyether oxygen as previously believed, but may also involve reaction with uorine and the possible formation of HF as an excellent leaving group.…”