Behavior of aluminum nitride ceramic surfaces under hydrothermal oxidation treatments

Aluminum nitride (AlN) ceramics were subjected to various hydrothermal oxidation treatments, such as high-temperature oxidation in air at 1000°C, water and high-pressure steam treatments, and copper sulfate plating solution at 70°C for 8 h. The resulting physical and chemical changes of these surfaces were characterized using various analytical techniques, such as surface profilometry, scanning electron microscopy (SEM), thermogravimetric analysis, and X-ray photoelectron spectroscopy (XPS). These studies indicate that the AlN ceramic surfaces are altered significantly by the surface treatments. The interaction of water as well as steam with the AlN ceramic surfaces resulted in the formation of AlOOH and Al(OH)₃. The thermally grown oxide layer (Al₂O₃) on AlN is more stable and offers protection from subsequent wet treatments. Surface treatment using a copper sulfate additive plating solution revealed significant alteration in the surface roughness value, from an initial value of 0.5 μm to a final value of 25.0 μm during 8 h of treatment at 70°C. SEM studies revealed the alteration of AlN surface morphology. The chemical change occurring on the AlN was analyzed using the XPS method, and results are presented