Speaker
Description
Titanium-based alloys have long been used for biomedical implants due to their biocompatibility, mechanical properties, and high corrosion resistance in body fluids. Moreover, their chemical composition and surface treatments can be tailored to enhance their performance. Electrochemical anodic oxidation (AO) is a promising method for improving implant integration with surrounding tissues and increasing their longevity [1].
In this study, we report the potential use of SQUID magnetometry for studying and screening the surface properties of Ti-$6$Al-$4$V alloy samples before and after AO treatment. The anodization was performed at voltages of $15$ V, $65$ V, and $90$ V using a $0.5\%$ wt. NaOH solution. Cylindrical samples ($\Phi$ $5\times5$ mm) were machined from Ti-$6$Al-$4$V alloys, grade ELI. Magnetic properties were measured using the Quantum Design MPMS XL-$7$T AC SQUID magnetometer.
The temperature dependence of mass magnetization, $M(T)$, was measured in zero-field cooling (ZFC) and field cooling (FC) modes at $50$ Oe. The DC magnetization, $M(H)$, was measured at $2$ K and $300$ K up to $20$ kOe. At room temperature, all samples exhibited nearly identical linear paramagnetic $M(H)$ curves. After correcting for the linear contribution of the sample holder and paramagnetism, nonlinear hysteresis loops were observed in the low-field range ($\pm5$ kOe), suggesting the presence of ferromagnetism, possibly due to structural defects in the surface oxide layer.
$M(T)$ dependencies in the temperature range of $300$ K to $30$ K showed a decrease with decreasing temperature, indicating antiferromagnetic ordering of magnetic moments. Below $5$ K, the $M(H)$ and $M(T)$ dependencies confirmed superconductivity with a critical temperature ($T_{C}^{ON}$) of approximately $5$ K. Additionally, the $M(T)$ dependencies were measured at $50$ kOe. A decrease of $T_{C}^{ON}$ to $\sim 3$ K can be observed, with the $M(T)$ value increasing by a factor of $103$ corresponding to the same magnetic field increase.
Significant differences in $M(H)$ dependencies were observed after correcting for the control samples (without AO) at $300$ K. These results suggest the potential use of SQUID magnetometry for studying and optimizing surface treatments of biomedical implants. Furthermore, we discuss certain aspects of the observed magnetic characteristics to better understand the existence of various exchange interactions.
Acknowledgements
This work was supported by the following projects: VEGA 2/0104/25, APVV-22-0328 and APVV-23-0366.
References
[1] A. Thakur and A. Kumar, “Recent advancements in the surface treatments for enhanced biocompatibility and corrosion resistance of titanium-based biomedical implants,” Applied Chemical Engineering, vol. 7, no. 1. Art and Science Press Pte. Ltd., Jan. 26, 2024. https://doi.org/10.24294/ace.v7i1.2042
