Elastic properties of ceramic thin structures

Ceramic thin structures are playing an increasingly greater role in advanced applications for engineered materials. Examples are ceramic coatings for protection against friction and wear and diamond like carbon films for semiconductor, optical, display and medical applications. During the development of these thin structures, measurements of their physical properties are essential for the optimization of the fabrication process. Chief among these are the elastic properties, which provide such information as the elastic moduli, density, porosity and film-to-substrate bond strength. Scanning acoustic microscopy was used to measure the velocity of Rayleigh waves in the 0.25 micron thick diamond like carbon films. The velocity could be correlated with mechanically obtained bond strength. Alumina plasma spray coatings. 250 micron thick, with varying levels of porosity were found to give velocities which depended linearly on the coating density. These results demonstrated the usefulness of ultrasonic techniques to characterize the properties of ceramic thin structures of various types and shed light on their fabrication processes.