The Usibor® AlSi coating can hardly be considered as a sacrificial
coating for 22MnB6 substrate because the difference of the corrosion
(and open circuit) potentials of these materials is less than 50 mV.
2. Even if not sacrificial for steel, Usibor® AlSi is an active coating which
is demonstrated by the direct measurement of the release rates of Al,
Fe and Si and by the analysis of corrosion products.
3. The corrosion products formed on Usibor® AlSi in the VDA 233-102
test conditions are mainly hydroxides and aluminosilicates while
under the SST conditions are mainly oxides of Al, Fe and Si. The
barrier effect on the oxygen reduction associated with corrosion