Material analysis by ultrasonic atomic force microscopy

Spray-dried ceramic powders (e.g., Al₂O₃) are composed of a plurality of granules, each of which, includes ceramic particles and organic binders. It is assumed that the binders become concentrated in the surface layer of the granule in accordance with its type or its volume mixed into a ceramic portion of the granule. However, evidence to prove the assumption was limited because conventional microscopes were not able to clearly visualize the segregation. This paper presents a technique for imaging detailed structure of the spray-dried ceramic powders with the ultrasonic-atomic force microscope (U-AFM). The distribution of binder vis-a-vis Al₂O₃ particles is highly resolved with good contrast. The distribution was confirmed by nano-indentation. Thus, the U-AFM, is shown to be a useful diagnostic tool for the development of approaches to spray-dried process evaluation.