Influence of Laser Treatment on the Corrosion Resistance of Cr(3)C(2)-25(Ni20Cr) Cermet Coating

The influence of the laser treatment on the corrosion resistance of the Cr(3)C(2)-25(Ni20Cr) cermet coating on the Al7075 (EN, AW-7075) substrate (Cr(3)C(2)-25(Ni20Cr)/Al7075) was investigated. The coating was produced by the cold sprayed (CS) method. The tested coatings were irradiated with a laser spot speed of 600 mm/min, 800 mm/min, and 1000 mm/min. The mechanical properties of the Cr(3)C(2)-25(Ni20Cr)/Al7075 were characterized by microhardness (HV) measurements. The surface and microstructure of the specimens were observed by ascanning electron microscope (SEM) and other assistive techniques. The corrosion test of materials wascarried out by using the electrochemical method in the acidic chloride solution. Cermet coatings perfectly protect the Al7075 substrate against contact with an aggressive corrosion environment. The laser remelting process of the Cr(3)C(2)-25(Ni20Cr) layer caused the homogenization of the structure cermet coatings. The irradiation with the laser beam eliminates microcracks and pores on the Cr(3)C(2)-25(Ni20Cr) surface. However, the best effect of improving the anti-corrosion properties of cermet coating was obtained for the lowest laser spot speed (i.e., 600 mm/min). It was found that the corrosion rate of the Cr(3)C(2)-25(Ni20Cr) cermet coating was reduced by more than two times compared to the highest speed of the laser spot.