The GD-OES elemental profile of the surface treated by dipping
in KMnO4 showed lower oxide layer thickness and the chemical
profile exhibits uniform distribution of manganese throughout the
oxide layer. The manganese concentration showed a decrease with
depth towards the metal oxide interface. However in the case of
steam treatment using KMnO4 solution, thickness of the produced
oxide layer was high, while the manganese content in the coating
was significantly lower in the top (∼200 nm) ofthe surface layer as
shown in Fig. 1 (e). The steam treatment ofPeraluman 706TM surface
with steam generated from aqueous solution ofHNO3 did not indicate the incorporation ofany other chemical species, neither at the
surface nor in the bulk ofthe oxide layer (Fig. 1 (f)). The GD-OES profiling of the AA1090 and AA6060 alloys surfaces (not shown) also
exhibited similar results as for Peraluman 706TM, therefore only the
summary of the results for AA1090 and AA6060 is presented.
Average thickness of the oxide layer calculated from the GDOES depth profiles on AA1090, AA6060 and Peraluman 706TM are
presented in Fig. 1 (d). In general, thickness of the oxide layer was
a function ofthe substrate type and chemistries. The highest thickness ofthe oxide layer resulted from steam treatment using KMnO4
on AA1090, AA6060 and Peraluman 706TM. Steam generated from
the aqueous solution with low concentration of HNO3 resulted in
the formation of relatively thick oxide on Peraluman 706TM and
AA6060 in comparison to AA1090. The increase in the concentration of HNO3 reduced the average thickness of the oxide layer on
Peraluman 706TM and AA6060. AA1090 alloy exhibited reduction
in thickness of oxide layer by the addition of HNO3 regardless of
the variation in concentration of HNO3 in aqueous solution