| Abstract: | The wear, friction and film forming characteristic of ethyl octadecenoate and methyl 12‐hydroxy ocatadecenoates, their thio and thiopyrophosphoro derivatives have been studied on HFRR friction and wear machine. The structural characteristics of chemisorbed films formed on the iron surfaces by these derivatives have been investigated using various analytical techniques such FT‐IR, Microreflectance Absorption and Proton Magnetic Resonance. It has been inferred that these films are primarily organic in nature. The constituents of these films are hydroxy alkyl and aryl ethers, unsaturated and condensed ring hydroxy ketones, aromatic hydroxy quinones and highly condensed aromatic structures chemically linked to iron sufaces through hydroxy, oxy, thia, oxyphosphoro and thiophosphoro moieties forming chelated and coordinated complexes. The antiwear and antifriction characteristic of alkyl octadecenoates increase with increasing polar linkages in the alkyl ocatadecenoate backbone. This is primarily due to the increase in number of sites amenable to chemisorption on the surfaces and consequently their reactivity. The antiwear and antifriction characteristic of derivatives of ethyl octadecenoates are inferior to the corresponding 12‐hydroxy methyl octadecenoates derivatives. This can be attributed to increased reactivity of 12‐hydroxy methyl octadecenoates derivatives at the surfaces due to an additional hydroxyl moiety. The films formed are highly condensed ring aromatic layered structures coordinating to iron atoms of the surface particularly in case of thiopyrophosphoro derivatives of methyl 12‐hydroxy octadecenoates. These films, as a consequence, provide lower wear and friction characteristics as compared to other types of organic films. These studies have led to much clear evidence of the intimate relationship between the chemical structure of the additives and their film forming characteristics. Copyright © 2006 John Wiley & Sons, Ltd. |
