Wear Scar Analysis by Ion Beam Technology

Abstract

Usually the lubricating effectiveness of loud-carrying additives in mineral oils is tested by measuring friction and wear of the lubricated machine elements. In most cases, these additives react with the metallic surface under the influence or frictional heating forming a complex film on the surface. This wear- and friction-reducing layer is continuously rubbed off and rebuilt. The ISSISIMS-system for surface analysis has been used to determine the concentration of elements in the surface layer of the wear scar, which had been formed in the presence of mineral oil, n-C_sZnDDP and MoS₂. To date, the following results have been obtained: 1. The fact has been confirmed that zinc (Zn) mid phosphorus (P) are easily detected by ion scattering spectroscopy (ISS). 2. The use of ISS also provides a depth profile of the variation of elerment concentration in the reaction layer. The contents can be expressed as percentages. 3. The concentrations of Zn and P decrease with growing depth. The thickness of the reaction layer appears to be of the magnitude of more than 800 Å. 4. Traces of Mo have been found in the surface film by the use of the SIMS-method. Hence, the solid lubricant seems to have a share in the formation of the reaction layer. The present investigations prove that the ISSISIMS-technology could become a valuable aid to the systematical development of load-carrying lubricant additives.