The friction and wear behaviors of some O-containing organic compounds as additives in liquid paraffin

The friction and wear behaviors of benzoic acid, benzoic alcohol, benzaldehyde, ethyl benzoate, and acetophenone as additives in liquid paraffin were examined on a four-ball machine. The morphologies of the worn surfaces were observed with scanning electron microscope. It was found that the antiwear ability of these compounds as additives in liquid paraffin at lower concentration (<0.5 wt.%) could be ranked as benzoic acid>benzoic alcohol>benzaldehyde>ethyl benzoate>acetophenone, which was in the same order of the polarity of these compounds. However, at higher concentration (>0.5 wt.%), the above sequence was ranked as benzoic alcohol>benzoic acid>benzaldehyde>ethyl benzoate>acetophenone, which was dominated by the different corrosiveness of the compounds. The rubbed surfaces were investigated using IR spectroscopy and the antiwear mechanism was discussed.