Tribofilmit

Tribofilmit is a term used in tribology to describe a thin, in-situ formed film that develops on sliding surfaces during friction and wear. The concept is closely related to the broader idea of a tribofilm or boundary film, and the term tribofilmit is occasionally used in literature to emphasize the chemical reactions that produce the film.

Formation and composition: Tribofilms form through interactions among surface materials, lubricant base oil, and additives under contact pressure and elevated temperature. They can arise from additive reactions (for example, zinc dialkyldithiophosphate and organic friction modifiers), lubricant decomposition products, or oxidative and sulfidation processes. The resulting layer is typically a few nanometers up to tens of nanometers thick, but thicker boundary layers can occur under severe loading.

Common constituents include metal oxides (such as iron or copper oxides), metal sulfides, carbonaceous layers (graphitic or amorphous carbon), and polymeric or organic compounds. The exact makeup depends on material pairings, lubricant chemistry, and operating conditions.

Functions: Tribofilms reduce direct metal-to-metal contact, lower friction, and protect surfaces from wear and corrosion. They can also modify surface roughness and influence heat transfer. The film is often non-uniform and dynamically formed and removed as conditions change.

Characterization and relevance: Researchers use techniques such as X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, transmission electron microscopy (TEM), and atomic force microscopy (AFM) to study tribofilms. Understanding tribofilms informs lubricant formulation and materials engineering, particularly for engines, transmissions, and bearings under high load or adverse conditions.