The Adsorption of Synovene on ZDDP Wear Tracks: A Sum Frequency Generation (SFG) Vibrational Spectroscopy Study
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- 作者：Michael T. L. Casford ; Paul B. Davies ; Tony D. Smith…
- 关键词：Sum frequency generation ; Steel ; ZDDP ; Lubrication
- 刊名：Tribology Letters
- 出版年：2016
- 出版时间：April 2016
- 年：2016
- 卷：62
- 期：1
- 全文大小：1,436 KB
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Chemistry
Tribology, Corrosion and Coatings
Surfaces and Interfaces and Thin Films
Theoretical and Applied Mechanics
Physical Chemistry
Nanotechnology - 出版者：Springer Netherlands
- ISSN：1573-2711
文摘
The adsorption of the lubricant additive Synovene on steel and on ZDDP/steel wear tracks from base oil has been investigated by sum frequency generation (SFG) vibrational spectroscopy, an interface specific technique. SFG spectra (resonances) were investigated in the C–H stretching region and arise from the aliphatic chains of the palm oil constituent of Synovene. The observation of SFG spectra means that Synovene is adsorbed at the oil/metal and at the oil/ZDDP/metal interfaces and that the aliphatic chains of Synovene have a net polarisation order with respect to the surface. The intense spectrum observed when the film is first formed decreases in intensity with increasing temperature. It is proposed that this is due to a decrease in film thickness as the film tends towards monolayer thickness. A dependence of the intensity and shape of SFG resonances on film thickness due to a thickness-dependent interference effect has been observed in other thin film systems, most notably lipid films on gold. Supporting evidence for the film thickness hypothesis comes from examining the spectra of different thickness films of palmitic acid on steel, one of the constituents of Synovene. The spectra on the wear track are less intense and less reproducible than on the bare metal. After periods of several days at room temperature the spectra on both surfaces gain in intensity implying a return to thicker layers of Synovene under cold conditions.