Property enhancement of surfaces by electrolytic micro arc oxidation

An oilfield tubular comprising:

• a substrate comprising a ferrous alloy;
• a first layer directly on a surface of the substrate, wherein the first layer comprises aluminum deposited by a thermal spray process, a cold spray process, a hot dip aluminizing (liquid) process, a vapor aluminizing process, a plasma and ion deposition process, or an electrolytic deposition process;
• and
• a second layer over a second portion of the first layer, wherein the second layer is between 1 μm and 40 μm thick and comprises aluminum oxide, and wherein the second layer is formed by oxidizing a first portion of the first layer by micro arc oxidation, wherein the second layer comprises an amount of aluminum oxide that is stoichiometrically equivalent to an amount of aluminum oxidized in the first layer, and wherein the second layer defines a plurality of pores, including at least one pore extending into the first layer;
• and
• a third layer filling the plurality of pores in the second layer, wherein the portion of the at least one pore in the first layer is filled with the third layer.