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.