An ultrasonic, nondestructive contact measurement technique was employed to detect and characterize the elastic anisotropy of a free-standing, plasma-sprayed alumina coating. Following this initial evalu-ation, a computer-assisted, ultrasonic anisotropic test bed was used to determine the anisotropic elastic stiffness constants of coatings produced by plasma gun currents of 600 and 400 A. The results showed that the plasma-sprayed alumina coatings are transversely isotropic; i.e., isotropic in the spraying direction. These coatings were characterized by five independent elastic stiffness constants. Coatings produced at 600 A plasma gun current showed higher elastic stiffness constants than those produced at 400 A plasma gun current. This increase appeared to be related to a decrease in the porosity content of the coatings pro-duced at the higher plasma gun current.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Materials Chemistry