Structure of tantalum coatings on NiTi substrate deposited by magnetron sputtering

The paper provides the results of studies of the structural-phase state of tantalum coatings prepared by magnetron deposition. The coatings were deposited on substrates made of titanium nickelide with a shape memory. The NiTi temperature during coating deposition did not exceed 100 °C. The structural-phase state of Ta was determined by X-ray diffraction at different stages of coating formation. It has been shown that at the initial stage of deposition, two-phase coatings (α- and β-Ta) are formed. The synthesis of the coating from Ta leads to the growth of interplanar distance of the B2 austenite phase in the crystallographic direction (100). The growth of interplanar spacing is caused by formation of microstresses during interaction with incident tantalum ions. The lattice parameters of the B19 ‘phase, responsible for appearance of the shape memory effect, do not change during deposition of the tantalum coating.

Tantalum as a Novel Biomaterial for Bone Implant: A Literature Review

Titanium (Ti) has been used in metallic implants since the 1950s due to various biocompatible and mechanical properties. However, due to its high Young’s modulus, it has been modified over the years in order to produce a better biomaterial. Tantalum (Ta) has recently emerged as a new potential biomaterial for bone and dental implants. It has been reported to have better corrosion resistance and osteo-regenerative properties as compared to Ti alloys which are most widely used in the bone-implant industry. Currently, Tantalum cannot be widely used yet due to its limited availability, high melting point, and high-cost production. This review paper discusses various manufacturing methods of Tantalum alloys, including conventional and additive manufacturing and also discusses their drawbacks and shortcomings. Recent research includes surface modification of various metals using Tantalum coatings in order to combine bulk material properties of different materials and the porous surface properties of Tantalum. Design modification also plays a crucial role in controlling bulk properties. The porous design does provide a lower density, wider surface area, and more immense specific strength. In addition to improved mechanical properties, a porous design could also escalate the material's biological and permeability properties. With current advancement in additive manufacturing technology, difficulties in processing Tantalum could be resolved. Therefore, Tantalum should be considered as a serious candidate material for future bone and dental implants.

The Effect of Thermal Oxidation on the Photothermal Conversion Property of Tantalum Coatings

In this study, tantalum coatings are deposited by a plasma spraying method aiming at enhancing the biocompatibility of the titanium implant. Tantalum oxide coatings are gained through the thermal oxidation of tantalum coatings at different temperatures for photothermal therapy. The effect of thermal oxidation on the morphology, composition, and structure of tantalum coatings has been studied. The UV–VIS–NIR spectra results, cancer therapy effect in vitro, and photothermal conversion properties among the tantalum oxide coatings under varied thermal treatment conditions are compared comprehensively. It has been proven that the tantalum coating treated at 200 °C exhibits the most intense NIR adsorption, the highest photothermal conversion effect, and the most excellent photothermal ablation effect in vitro. The results reveal that incomplete oxidation at a low temperature leads to the formation of oxygen vacancies, which narrow the band gap; this promotes its photothermal conversion ability.

Mechanical, Electrochemical and Osteoblastic Properties of Gradient Tantalum Coatings on Ti6Al4V by Prepared Plasma Alloying Technique

Plasma alloying technique capable of producing metallic coatings with metallurgical bonding has attracted much attention in dental and orthopedic fields. In this study, the effects of temperature and time of plasma tantalum (Ta) alloying technique on the mechanical, electrochemical, and osteoblastic properties of Ta coatings were systematically investigated. Ta coatings prepared at 800 °C possess better interfacial strengths than those prepared at 750 and 850 °C, and the interfacial strength increases with prolonged alloying time (30–120 min). At 800 °C, however, the increased proportion of the soft Ta deposition layer with alloying time in the whole coating impairs the surface mechanical properties of the entire coating, as convinced by decreased microhardness and wear resistance. Moreover, Ta coatings exhibit better corrosion resistance than the Ti6Al4V substrate in Dulbecco’s modified Eagle medium. The enhanced adhesion and extracellular matrix mineralization level of osteoblasts demonstrate the better cytocompatibility and osteogenic activity of the Ta coating. Ta30 (Ta coating prepared at 800 °C for 30 min) exhibits excellent mechanical, electrochemical, and osteoblastic behaviors and is promising in biomedical applications.

DEPENDENCES OF HELIUM RETENTION IN TUNGSTEN AND TANTALUM COATINGS IRRADIATED WITH He+ IONS ON FLUENCE AND TEMPERATURE

The processes of helium accumulation and thermal desorption for tungsten and tantalum coatings deposited on a stainless-steel substrate with an intermediate titanium layer were studied at various temperatures of the samples when irradiated with He+ ions to various fluences. The dependences of the concentration of captured helium and the form of the spectra of its thermal desorption into vacuum were found both on the fluence of He+ ions and on the temperature of the samples upon irradiation. Possible mechanisms for the accumulation and thermal desorption of helium, as well as the formation of defects in the crystal lattice of the samples, are discussed.

Effect of the Substrate Biasing on the Structure and Properties of Tantalum Coatings Deposited Using HiPIMS in Deep Oscillations Magnetron Sputtering Mode

The influence of energetic ion bombardment on the properties of tantalum coatings was studied. To achieve such energetic ion bombardment during the deposition process of tantalum coatings, a combination of deep oscillation magnetron sputtering (DOMS), an ionized physical vapour deposition technique, with substrate biasing was used. The substrate biasing was varied between 0 and −120 V. In this work, the structure (XRD), microstructure (SEM), surface morphology (AFM) and hardness, and Young’s modulus (nanoindentation) of the coatings were characterized. The results show with the use of such conditions it was possible to deposit a pure α-Ta (the most desired at industrial level) with improved mechanical properties (hardness equal to 22.4 GPa and Young’s modulus equal to 235 GPa). The roughness of the Ta coatings decreases up to values of about 1 nm with an increase of substrate biasing. It was possible to deposit very dense Ta coatings with 2 µm of thickness. Therefore, these results are significantly different than in previous works, offering Ta coatings with a combination of very interesting properties.