Synthesis of NiCrAl/MgO-ZrO₂ cermet powders by chemical method for functionally graded coatings

Functionally graded materials (FGMs) are receiving great attention as they provide optimum thermal and mechanical properties without a discrete interface between two materials. In order to control the chemical composition and microstructure of FGMs, NiCrAl/MgO-ZrO₂ cermet powders were successfully developed in the present work. The NiCrAl/MgO-ZrO₂ powders were synthesized from a solution of NiCrAl, ZrO₂ and Mg hydroxide carbonate precursors using chemical synthesis. The powders were dried at 125 °C for 3 h and then pellet samples were sintered at 1381 °C for 30 min under N₂-5%H₂ atmosphere. The powders were characterized by scanning electron microscope, energy dispersive spectroscopy, X-ray mapping and X-ray diffraction. The obtained results showed that the optimum particle sizes of NiCrAl/MgO-ZrO₂ powders were between 45 and 90 μm. Microstructural studies have shown a uniform mixing in the cermet powders. It was also found that ZrO₂, MgO, MgZr₇O₁₄, Ni, Cr and Ni₅Al₃ phases were present in the cermet powder.