Zirconia restorations have been used successfully for years in dentistry owing to their biocompatibility and good mechanical properties. Because of their lack of translucency. zirconia cores are generally veneered with porcelain. which makes restorations weaker due to failure of the adhesion between the two materials. https://www.roneverhart.com/Western-Digital-Re-WD6001FSYZ-6TB-7-2K-RPM-SATA-6Gb-s-128MB-3-5-Hard-Drive/