Correlation of Spectrographic Oil Analysis Data With SEM and X-Ray Data by Direct Examination of Particles in Hydraulic Oils

Abstract

The Spectrographic Oil Analysis Program (SOAP) is a standardized procedure for spectrochemically determining the average analysis of all particles present in a sample of oil from hydraulic or lubricated systems. In the present program scanning electron microscopy (SEM) and X-ray analysis were employed to study the morphology and chemistry of individual particles collected from oil samples. Also, a large collection of particles could be studied for obtaining an average analysis of all the particles in the analyzed area. Comparisons of SEM/X-ray data with SOAP data, and their correlation with conditions of parts showed good correlation for the aluminum-containing particles in the aircraft hydraulic system. Though not detected by SOAP, SEM/X-ray analysis showed several particles containing silicon (identified mostly as silica with X-ray diffraction), most of which were typically larger than 5 microns.