Percolative Mechanism of Aging in Zirconia-Containing Ceramics for Medical Applications

TL;DR

This paper investigates the aging mechanism in zirconia-containing ceramics used in medical implants, identifying a critical composition threshold to prevent aging-related fractures in hip prostheses.

Contribution

It introduces a percolation-based understanding of aging in zirconia ceramics and determines a specific compositional limit to avoid future aging issues.

Findings

Identified a 16 vol.% Y-TZP threshold in alumina/Y-TZP composites.

Linked the aging problem to the percolation threshold measured by IR reflectance.

Provided guidelines to improve the longevity of zirconia-based medical implants.

Abstract

Recently, several episodes of fracture of zirconia ceramic femoral heads of total hip prostheses have alarmed the medical and scientific community regarding aging problems in zirconia prostheses. Such fractures cause immediate local tissue reactions, which require urgent medical intervention to prevent further complications. As a result, it has been promoted that yttria-stabilized zirconia (Y-TZP) hip prostheses be substituted by alumina and alumina/Y-TZP ceramics. In the present investigation, we have found an upper limit of Y-TZP concentration in alumina/Y-TZP composites (16 vol.%) to avoid future aging problems. This limit coincides with the percolation threshold measured by infrared (IR) reflectance in a series of alumina/Y-TZP composites.