Study of the corrosion resistance of a TiAlN /Cr3C2-25NiCr based duplex coating

The duplex coating technique combines two processes: the deposition of a thermally sprayed coating and the deposition of a thin coating through the technique of Physical Vapor Deposition (PVD). The coatings produced by the PVD technique have as basic characteristics the formation of a thin layer (in the order of 0.5 to 10 μm, in large scale production). These coatings have high hardness, low coefficient of friction and are extremely resistant to wear as well as to corrosion. Because they exhibit these characteristics these coatings are commonly used in cutting tools and in dies in forming processes. Applications in other sectors have been gaining prominence, especially the oil and gas sectors. In these cases, the resistance to electrochemical corrosion of coatings is a very important factor. The duplex coatings, resulting from the deposition of a Cr3C2-25NiCr can to introduce a higher resistance to abrasion. The Waspalloy samples with coatings were initially characterized by optical microscopy and scanning electron microscopy, a Na2SO4 and V2O5 oxides were added to surface to induce a corrosion at 700ºC.