BIOLOX® delta Ceramic Material
The BIOLOX delta Ceramic femoral heads are made from a new alumina matrix composite developed by CeramTec AG. This material is a high-performance ceramic that meets the increased demands regarding durability of the implants in young, active and heavy patients.
Material Science
BIOLOX delta is an aluminum oxide matrix composite ceramic consisting of approx. 75% alumina (Al2O3), 24% zirconia (ZrO2) and other trace elements. The pink color is due to the chromium oxide (Cr2O3) that improves the hardness of the composite material.
Alumina provides the material's hardness and wear resistance, while zirconia, together with other additives, provides improved mechanical properties. These properties are achieved, among other things, as a result of the high strength, the high density of the material and the very small grain size of the alumina matrix.
The result is a high-performance ceramic that offers the same advantages as BIOLOX® forte: excellent biocompatibility, low wear, high hardness, good mechanical performance, outstanding chemical and hydrothermal stability.
Microstructure of BIOLOX delta (Courtesy of CeramTec AG).
The Microstructure
The first toughening mechanism used in BIOLOX delta material results from the introduction of small, homogeneously distributed yttria-stabilized tetragonal zirconia particles (Y-TZP) in a stable alumina matrix. The spatial separation of these zirconia particles reduces the likelihood of structural transformation and prevents the initiation or propagation of cracks.
The principle of transformation-toughening by small zirconia particles, which are dispersed in the alumina matrix.
1. Alumina grain
2. Zirconia grain
The second toughening mechanism is achieved by the addition of strontium oxide, which forms platelet-like crystals. These platelets dissipate energy by deflecting cracks, thereby increasing material strength and toughness.
The principle of reinforcement by platelet-like crystals in an alumina matrix.
1. Alumina grain
2. Zirconia grain
3. Platelet-like crystal