Hydrothermal calcification surface modification of biomedical tantalum
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Hydrothermal calcification surface modification of biomedical tantalum Di-Feng Luo, Pan Ning, Fan Zhang, Yan Zhou, Hong-Mei Zhang, Tao Fu*
Received: 15 September 2019 / Revised: 26 November 2019 / Accepted: 29 July 2020 Ó The Nonferrous Metals Society of China and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Tantalum (Ta) as a new type of medical metal is now utilized in several orthopedic applications due to its excellent fracture toughness and workability, high corrosion resistance, good biocompatibility and X-ray visibility, but it lacks bioactivity. Therefore, pure Ta was hydrothermally calcified in CaHPO4 solution at 120–200 °C here for bioactive surface modification. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Raman spectroscopy analyses show that thin tantalum oxide film with a few calcium phosphate precipitates is formed at the surface after the treatment at 200 °C. The hydrothermally treated sample has good hydrophilicity and corrosion resistance evidenced by the water contact angle measurement and the potentiodynamic polarization test, respectively, and it can induce the formation of apatite layer after soaked in the simulated body fluid for 1 week. The present method would be applicable for bioactive surface modification of tantalum implants with irregular shapes and even porous structure. Keywords Tantalum; Hydrothermal; Calcification; Corrosion; Bioactivity
D.-F. Luo, P. Ning, F. Zhang, Y. Zhou, H.-M. Zhang, T. Fu* Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an 710049, China e-mail: [email protected] D.-F. Luo Bioinspired Engineering and Biomechanics Center, Xi’an Jiaotong University, Xi’an 710049, China
1 Introduction Tantalum (Ta) as a new type of medical metal has received special attention in recent decades due to the merits that it possesses, such as excellent fracture toughness and workability, high corrosion resistance, good biocompatibility [1–4] and visibility by current in vivo imaging technology due to its X-ray opacity. Tantalum is now utilized in several orthopedic applications such as hip and knee arthroplasty, spine surgery, and bone graft substitutes [5, 6]. Tantalum implants have significantly better initial stability than that of conventional titanium implants [1]. However, there are still limitations for surgical and orthopedic tantalum implants. First, tantalum is a bioinert, rather than a bioactive material. Bioactive materials can form chemical bond to living bone through the bone-like apatite layer, while bio-inert materials are isolated from surrounding bone by fibrous encapsulation. In order to enhance the bonding of tantalum to bone, bioactive coatings should be applied. Like titanium, the alkali-treated tantalum forms a bioactive tantalate layer containing alkali ions, which could induce the formation of apati
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