Improved Hardness and Wear Resistance with IonGuard®

Many medical device companies turn to N2 Biomedical to improve the wear resistance and hardness of Titanium and Cobalt Chromium implants using its IonGuard® Ion Implantation process.

The increased diagnosis of patients with nickel allergies has increased the demand for titanium implants. However, untreated titanium articulating surfaces have been shown to produce metallic particles resulting in an adverse tissue response and high third-body wear. The FDA has long-standing guidance that articulating titanium components be treated to prevent metal particulate release and reduce third-body wear. The same guidance specifically highlights nitrogen ion implantation as a suggested surface treatment.

The micro-hardness of titanium-based alloys treated using ion implantation has been studied by various groups1-3. IonGuard® uses high ion beam energies and doses (total number of ions bombarding the surface) that result in increased hardness and wear resistance. Up to a three-fold increase in the micro-hardness can be achieved on the surface of nitrogen ion implanted Ti-6Al-4V. Figure 1 shows Knoop micro-hardness improvement resulting from ion implantation treatment.

Figure 1: Knoop micro-hardness of IonGuard®-treated Titanium versus Untreated Titanium.6

The improved wear, fatigue and corrosion resistance of titanium have also been studied widely by several research groups1-5. Oliver, Hutchings and Pethica1 presented, in their classic publication, that nitrogen ion implanted titanium surfaces, when tested on a pin-on-disc wear tester, showed 500 times reduction in wear. These authors also reported a three-fold reduction in the coefficient of friction as a result of nitrogen ion implantation. Bolster, Singer and Vardiman6 reported a 60-70 times increase in relative wear resistance of ion implanted specimens in abrasive wearing conditions. In addition, these authors concluded that the relative wear resistance of ion implanted titanium is comparable to the wear resistance of titanium nitride coated materials.

Zhang7 et al also studied the wear resistance of IonGuard® implanted Ti, Ion Nitrided Ti, and Co-Cr samples in contact with UHMWPE plates. They reported better performance with IonGuard® over Nitrided Ti and parity or slightly superior performance to Co-Cr.

The use of titanium in load bearing implants is increasing. However, the use of untreated titanium is not recommended. IonGuard® has a 30 year history of improving the surface hardness and lubricity of load-bearing implants making implants safer and longer lasting. N2 Biomedical’s proprietary Ion Implantation Surface Treatment and IBAD Nano-Engineered Coating technologies transforms the surfaces of titanium medical implants and devices to last longer, fight infection, improve biocompatibility and have durable aesthetics.

Learn more about IonGuard® and read our whitepaper here.

 

References

  1. Oliver WC, Hutchings R, Pethica JB: The wear behavior of nitrogen- implanted metals. Metallurgical Transactions. 1984;15A:2221-2229.
  2. Sioshansi P: Tailoring surface proper- ties by ion implantation. Materials Engineering. 1987.
  3. Sioshansi P: Improving the properties of titanium alloys by ion implantation. Journal of Metals. 1990;30-31.
  4. Lombardi AV Jr, Mallory TH, Vaughn BK, Drouillard P: Aseptic loosening in total hip arthroplasty secondary to osteolysis induced by wear debris from titanium-alloy modular femoral heads. J Bone Joint Surg. 1989;71A:1337-1342.
  5. C. Clarke, H. A. McKellop, P. McGuire, R. Okuda, and A. Sarmiento, “Wear of Ti-6Al-4V implant alloy and ultrahigh molecular weight poly-ethylene combinations,” in Titanium Alloys in Surgical Implants, ASTM STP 796, H. A. Luckey and Fred Kubli, Jr. (eds.), ASTM, Philadelphia, 1983, pp. 136-147.
  6. Bolster RN,,Singer IL, Vardiman RG: Composition, structure and wear resistance of Ti-6Al-4V implanted with carbon and boron to high doses. _Surface & Coatings Technology. 1987;33:469-477.
  7. Jianquiang Zhang, Xiaoshong Zhang, Guo Zintang, Li Hengde: Comparison of wear resistance of ion implanted surgical Ti-6Al-4V with other alloys. Mater Res Soc Sympos Proc. 1986;55:229.