Investigation of the structure and tribological characteristics of monolayers deposited by the Langmuir-Blodgett technique

A series of partially fluorinated ethyl esters with the same hydrophobic group length were deposited by the Langmuir-Blodgett (LB) technique on an Al plate coated with a NiP film. Film structures were inferred through surface pressure-molecular area isotherms (pi-A isotherms). The results indicate that the film structures are determined by van der Waals forces between hydrophobic chains. Stronger mutual forces lead to stable solid films. Frictional properties and load-carrying capacities of the monolayers were evaluated using a ball-on-plate-type sliding apparatus. The friction coefficient and load-carrying capacity are dependent on the monolayer film structures. The solid film shows a lower friction coefficient and a higher load-carrying capacity. Friction tracks of the monolayers were examined by time-of-flight secondary ion mass spectroscopy (TOF-SIMS). We found that the liquid film may be a fluid monolayer, and that the structure of the solid film changes under frictional force. (C) 2000 Elsevier Science B.V. All rights reserved.