Infrared confocal imaging for inspection of flaws in yttria-stabilized tetragonal zirconia polycrystal (Y-TZP)

Custom made medical yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) components require a high standard of machining and inspection techniques to ensure high reliability of the manufactured parts. Due to heat generated during machining processes, which in turn can cause cracking, the strength of Y-TZP ceramics can be compromised. Thus, a novel confocal mid-infrared transmission imaging technique is introduced in this paper. It provides enhanced imaging capabilities for flaws and cracks introduced into the bulk of the component compared to previously developed imaging techniques. We demonstrate that micrometre scale cracks can be identified in Y-TZP components up to 3.5 mm thick with an imaging resolution of approximately 30 mu m, and also show that macro scale flaws can be observed in the volume of Y-TZP ceramics of up to 3.5 mm thick.