Characterization of Metallized Alumina Ceramics

The metallization of alumina ceramics (92 pct purity) was performed by the molybdenum-manganese (Mo−Mn) process in moist hydrogen and nitrogen atmosphere in the temperature range of 1523 K to 1673 K (1250 °C to 1400 °C) for 10 minutes with a dew point of 293 K (20 °C). The metallized alumina ceramics were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), evaluation of metallic coating adhesion by scratch test, and nanohardness measurement. XRD identified the phase composition of the metallized layer surface. The surface and cross-section microstructures of the metallized alumina ceramic specimens were observed by SEM. An EDX analysis across the metallized alumina specimens determined the elemental compositions at the selective regions. The scratch test results showed that the adhesion of the metallized layer on alumina ceramics enhanced with the increase in metallization temperature. Nanohardness measurements along the cross-sectional region of the metallized alumina ceramics exhibited the gradual change in the nanohardness values from the alumina substrate to the metallizing layer. Furthermore, it was observed that the nanohardness of interfacial and metallizing regions was enhanced slightly with increasing processing temperature.