[PO-O1] Poster Session 1

[P1-83] Adsorption property of a fatty acid on iron surface with grain boundary

^○Yuki Uchiyama, Yoshinori Shiihara, Ivan Lobzenko (Toyota Technological Institute, Japan)

Reducing the coefficient of boundary friction on steel surfaces is one of key technologies to improve the efficiency of machines such as automotive engines. It has been shown that the boundary friction on nanostructured steel surfaces in the sliding test using particular lubricant is smaller than the friction of normal steel surfaces [1]. This difference between the nanostructured and a normal surfaces lies in the density of the grain boundary as a surface defect. The surface defect can attract lubricant molecules and enhance lubricating film formation on metal surfaces. This can be one of the mechanism that induces the friction reduction on the nanosructured steel surface. In this work, using first principles calculations, the adsorptivity of a lubricant molecule, a fatty acid, on iron surfaces has been studied.The chemical adsorption of fatty acids is expected to be enhanced at the site near the crystal grain boundary which may have high chemical activity. Adsorption energy calculations were preformed for acetic acids as the simplest fatty acids. Adsorbability of a Fe (110) surface with symmetrical tilt Σ3 (111)grain boundarywas compared to clean Fe(100), (110) and (111) surfaces. As a result, we found that the molecule can adsorb on the particular site on grain boundary more strongly than that on Fe surfaces without grain boundary. [1]

Yoshikazu Todaka, Kenichi Toda, Motohiro Horii, Minoru Umemoto, Tetsu-to-Hagané 101, 10 (2015)