Aryl Amine Antioxidant Determinations in Ester Lubricants

摘要

Many, if not all, of today's high performance lubricants, especially in jet engines, use ester basestocks inhibited with aromatic amines. Work at NRL has shown that severe and rapid depletion of the antioxidant usually precedes lubricant breakdown and subsequent mechanical failure. Therefore, an assessment of the antioxidant levels in these lubricants will serve as one measure of lubricant condition and, potentially, a lubricant's remaining lifetime. We have developed two rapid techniques to detect the most common classes of aryl amines used in today's ester lubricant formulations, the phenyl alpha-napthylamines, diphenylamines and phenothiazines. One technique is based on a spectrochemical methodology. Here, the time evolution of the formation of an amine-indicator complex at various visible wavelengths allows the determination of phenyl alpha-naphthylamine (PAN), octylated PANs and alkylated disphenylamines. The second is based on voltammetry. Keywords: Aryl amine antitoxidants, Ester lubricants. (MJM)