Using of SEM and EDS for Analysis of Internal Diesel Injector Deposits

摘要

In the framework of the FVV supported project "Fuel Alternations II" the potential of EDS (energy dispersive X-ray spectroscopy) in combination with the SEM (scanning electron microscopy) for the analysis of internal diesel injection deposits (IDID) were studied. SEM allows the topographical study of the surface layers while analysis by EDS provides the elementary composition of the surfaces. By variation of the acceleration voltage the spectra can be discretely recorded corresponding to the depth of the layer. SEM images of IDID show the landscape structures of the deposit layer as well as some deposit-free areas. This supports the theory that the deposits form as insolubles in the liquid phase, coalesce and sediment on the surface. The EDS investigations suggest the existence of an oxide film at the boundary between the deposit layer and the metal surface. A similar film formation is known to form from lubricating oils as well.