Detonation Deposited Fe-Al Coatings Part III: Morphology of the Ni(Cr) and Ni(Al) Interlayers and Fe-Al Coating Sprayed onto The 045 Steel Substrate

Detonation Deposited Fe-Al Coatings Part III: Morphology of the Ni(Cr) and Ni(Al) Interlayers and Fe-Al Coating Sprayed onto The 045 Steel Substrate The morphology of interlayars and the coating of Fe-Al phase detonation sprayed (DGS) on the substrate of 045 steel was analysed in the work. The Ni(Al) layer, first from the substrate side consisted of Ni with inclusions of Al oxide. The second deposited layer was Ni(Cr), which contained lamellas of Cr in the Ni matrix. The phases present in the transition layers and in the coating were identified with SEM, and EDX methods (linear and point changes of chemical composition). The identification was confirmed with the X-ray technique and TEM microstructure analysis. It was established that Al oxides and AlNiO phases appeared in the DGS process after partial melting and oxidation of Al particles, while in the not melted part of grains small grain morphology was observed. Using the X-ray method, the FeAl[2]O[4], Fe[3]Al and FeAl phases were identified in the coating, the Cr and Cr[2]Ni[3] phase in the Ni(Cr) interlayer as well as pure nickel and the NiAl phase in the Ni(Al) interlayer. The occurrence of brittle phases of Al oxide and AlNiO phases near the boundaries of layers might result in the increase of tendency to delamination. Hence the reduction of the Al content seems advantageous from the point of view of mechanical properties of the joint.