With its know-how, the Materials Engineering unit at Audi Quality Assurance supports material challenges across the entire process chain, from product creation to product testing.
Focused ion beam (FIB) – innovative analysis tool
In addition to conventional analysis techniques, such as light-optical microscopy, Audi’s materials experts also use scanning electron microscopes for analysis. These allow a significantly higher depth of analysis of the materials.
Scanning electron microscopy (SEM) provides high-resolution images of fracture surfaces or important insights into the concentration and distribution of chemical elements in the material being studied.
Materials Engineering has been using a focused ion beam (FIB) for four years now. This makes the brand with the four rings a pioneer among car manufacturers. The combination of an imaging scanning electron microscope and an ion gun as an abrasive tool makes it possible to create high-resolution, cross-sectional images of material systems.
The functional principle of the focused ion beam: the gallium ion beam of the FIB first digs a hole invisible to the human eye into the material under investigation. An integrated scanning electron microscope then provides a high-resolution, cross-sectional view below the material surface. The typical cutting depths of 5 to 50 micrometers – with widths of 50 to 100 micrometers – are achieved after two to five hours of cutting time. A major advantage is that the experts can follow the cutting process live with the scanning electron microscope.
At the same time, compared with mechanical preparation methods like the creation of grinding patterns, the FIB offers the big advantage in the case of complex material combinations (e.g. hard, thin coating of soft substrates) of only leaving behind minimal preparation artifacts. This refers to changes of a distorting nature, such as those on interfaces which result from such preparation.
In addition to the typical analyses in the field of surface technology, such as anti-corrosion coatings and paints, Audi uses FIB technology for almost all automotive-relevant raw materials and material systems: metal, glass, ceramics, polymers and even leather.