Patent ID: 7354660

Claim:
An alloy composition with a multi-layer surface oxide film resistant to metal dusting corrosion comprising: a) an alloy (PQR) having a surface, wherein P is a metal selected from the group consisting of Fe, Ni, Co, and mixtures thereof wherein the amount of Fe, Ni, and/or Co comprises at least about 40 wt % of (PQR), Q is an alloying metal comprising Cr, Mn, and Al wherein the amount of Cr, Mn, and Al comprises at least about 20 wt % of (PQR), and R is an alloying element wherein R comprises about 0.01 wt % to about 5.0 wt % of (PQR), and b) a multi-layer oxide film on said surface of said alloy (PQR), wherein said multi-layer oxide film comprises at least three oxide layers, wherein a first oxide layer comprises an oxide selected from the group consisting of a manganese oxide, a manganese chromate, a chromium oxide, and mixtures thereof, and is an outer layer located adjacent to a third oxide layer, a second oxide layer comprises aluminum oxide, and is located between the surface of said alloy (PQR) and said third oxide layer, and said third oxide layer comprises manganese aluminum oxide, and is located between said first oxide layer and said second oxide layer.