Increased Fracture Strength and Excellent Wear Properties


Surgeons all over the world put their faith in our pink-colored BIOLOX®delta ceramic. The very color gives surgeons the certainty that they’re using implants of the highest quality and reliability for their patients – from CeramTec. BIOLOX®delta is the only ceramic with 15 years of successful clinical experience – with more than 8 million components sold.


BIOLOX®delta is the newest material in the BIOLOX® family. It is a mixed oxide ceramic with increased fracture strength, excellent wear properties and unlimited biocompatibility. Since its launch 6.6 million BIOLOX®delta ball heads and over 2 million inserts (as of end of December 2017) have been sold worldwide.

Further Research: Chromium has no Effect on Hardness of BIOLOX®delta

BIOLOX®delta is a zirconia toughened alumina ceramic (ZTA) for biomedical applications. As published, for example in 2001, the composition of BIOLOX®delta includes SrO, Y2O3, and Cr2O3 [1]. Strontia is included for the formation of platelets inside the matrix, which support the toughness of the material. Yttria is included in order to control the transformation mechanism of the zirconia phase.

According to [1], it was previously stated that the inclusion of chromia leads to improved hardness in a ZTA material. However, an earlier scientific study on this subject reveals a measurable increase in hardness only at a chromia content much higher than present in BIOLOX®delta [2]. Accordingly, further scientific literature suggests that the presence of chromia within a limited range does not influence the hardness of a ZTA material [3]. Further, internal CeramTec experiments have also observed no increase in hardness due to the presence of chromia. As such, CeramTec undertook a comprehensive examination in order to isolate the impact, if any, of chromia on hardness in BIOLOX®delta. Results of this analysis are described herein.

[1] W. Burger, H.G. Richter, High Strength and Toughness Alumina Matrix Composites by Transformation Toughening and „In Situ“ Platelet Reinforcement (ZPTA) – the New Generation of Bioceramics, Key Engineering Materials Vols. 191-195 (2001), 545 – 548
[2] R.C. Bradt, Cr2O3 Solid Solution Hardening of Al2O3, Journal of the American Ceramic Society (1967) [5], 1, 54 – 55.
[3] G. Magnani, A. Brillante, Effect of the composition and sintering process on mechanical properties and residual stresses in zirconia alumina composites, Journal of the European Ceramic Society 25 (2005) 3383-92

  • Whitepaper

    The effect of chromia content on hardness of zirconia platelet toughened alumina composites

    Dr. Meinhard Kuntz

Applications for BIOLOX®delta

The main difference between BIOLOX®forte and BIOLOX®delta is BIOLOX®delta’s greater strength. However, the reliability of a ceramic implant depends on the actual loads it is subjected to, which are greatly influenced by the geometry, the design of the entire implant system, the surgical technique used and the post-operative behavior of the patient.

BIOLOX®delta was developed to open up a broader range of clinical uses including those which were not possible using BIOLOX®forte.

BIOLOX®delta Toughening Mechanism

Fig. 1 The principle of transformation toughening using yttria-stabilized zirconia particles,
which are dispersed in the alumina matrix.

The first toughening mechanism is the introduction of yttria-stabilized tetragonal zirconia particles (Y-TZP) in a stable alumina matrix. These Y-TZP particles are spatially separated from each other in order to reduce the likelihood of structural transformation as well as to prevent the initiation and propagation of cracks.

The dispersion of fine particles in the matrix also improves the fracture strength and toughness of BIOLOX®delta components as shown in Fig. 1. This mechanism functions like the airbag in your car.

The second reinforcement mechanism is achieved by adding an oxide which forms platelet-like crystals. These platelets dissipate energy by deflecting cracks, thereby increasing the strength and toughness of BIOLOX®delta.

  • BIOLOX® Ceramic-on-Ceramic

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