Alicja Kazek-Kęsik

Application of plasma electrolytic oxidation to bioactive surface formation on titanium and its alloys

In this work, a review of the literature concerning the surface modification of implants composed of titanium and titanium alloys by plasma electrochemical oxidation (PEO), also known as micro-arc oxidation (MAO), is presented. The application of this process allows for the formation of oxide layers with different porosities on implants. Moreover, it is possible to enrich these oxide layers with species contained in solutions used for anodising, yielding suitable surface chemical properties. Anodising titanium implants in solutions containing compounds of calcium and phosphorous leads to the formation of bioactive layers and significantly reduces the time required for the osseointegration of implant to bone. Studies of the PEO process with respect to titanium implants have been conducted by a large number of research centres, and their results have been applied to the production of a new generation of titanium implants.

Electrochemical and biological characterization of coatings formed on Ti–15Mo alloy by plasma electrolytic oxidation

β-Type titanium alloys are considered the future materials for bone implants. To improve the bioactivity of Ti-15Mo, the surface was modified using the plasma electrolytic oxidation (PEO) process. Tricalcium phosphate (TCP, Ca3PO4), wollastonite (CaSiO3) and silica (SiO2) were selected as additives in the anodizing bath to enhance the bioactivity of the coatings formed during the PEO process. Electrochemical analysis of the samples was performed in Ringers solution at 37°C. The open-circuit potential (EOCP) as a function of time, corrosion potential (ECORR), corrosion current density (jCORR) and polarization resistance (Rp) of the samples were determined. Surface modification improved the corrosion resistance of Ti-15Mo in Ringers solution. In vitro studies with MG-63 osteoblast-like cells were performed for 1, 3 and 7 days. After 24h, the cells were well adhered on the entire surfaces, and their number increased with increasing culture time. The coatings formed in basic solution with wollastonite exhibited better biological performance compared with the as-ground sample.

Surface characterisation of Ti–15Mo alloy modified by a PEO process in various suspensions

This paper reports on the surface modification of a Ti-15Mo alloy by plasma electrolytic oxidation (PEO). This process was carried out in solutions of 0.1M Ca(H2PO2)2 with various concentrations of tricalcium phosphate (Ca3(PO4)2), wollastonite (CaSiO3), or silica (SiO2) using voltages of up to 350V. The surface microstructure (SEM, cross-section of coating), roughness and chemical composition (energy-dispersive X-ray spectroscopy, thin layer X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy) of the porous oxide layers were investigated. The concentration of powder added to the solution changed the chemical composition and morphology of PEO coatings on the Ti-15Mo alloy surface. Calcium and phosphorous compounds were detected in the coatings formed on the substrate by the PEO process at 300V.

Modification of niobium surfaces using plasma electrolytic oxidation in silicate solutions

Herein, a study of the plasma electrolytic oxidation (PEO) of niobium in an anodising bath composed of potassium silicate (K2SiO3) and potassium hydroxide (KOH) is reported. The effects of the K2SiO3 concentration in the bath and the process voltage on the characteristics of the obtained oxide layers were assessed. Compact, barrier-type oxide layers were obtained when the process voltage did not exceed the breakdown potential of the oxide layer. When this threshold was breached, the morphology of the oxide layer changed markedly, which is typical of PEO. A significant amount of silicon, in the form of amorphous silica, was incorporated into the oxide coatings under these conditions compared with the amount obtained with conventional anodising. This surface modification technique led to an improvement in the corrosion resistance of niobium in Ringer’s solution, regardless of the imposed process conditions.

in vitro bioactivity investigations of Ti‐15Mo alloy after electrochemical surface modification

Titanium and its aluminum and vanadium-free alloys have especially great potential for medical applications. Electrochemical surface modification improves their surface bioactivity and stimulates osseointegration process. In this work, the effect of plasma electrolytic oxidation of the β-type alloy Ti-15Mo surface on its bioactivity is presented. Bioactivity of the modified alloy was investigated by immersion in simulated body fluid (SBF). Biocompatibility of the modified alloys were tested using human bone marrow stromal cells (hBMSC) and wild intestinal strains (DV/A, DV/B, DV/I/1) of Desulfovibrio desulfuricans bacteria. The particles of apatite were formed on the anodized samples. Human BMSC cells adhered well on all the examined surfaces and expressed ALP, collagen, and produced mineralized matrix as determined after 10 and 21 days of culture. When the samples were inoculated with D. desulfuricans bacteria, only single bacteria were visible on selected samples. There were no obvious changes in surface morphology among samples. Colonization and bacterial biofilm formation was observed on as-ground sample. In conclusion, the surface modification improved the Ti-15Mo alloy bioactivity and biocompatibility and protected surface against colonization of the bacteria.

Effects of Sn and Mo Contents on the Electrochemical Behavior of Biomedical Ti-Mo-Sn Alloys Prepared in the Powder Metallurgy Process

The aim of this study was to investigate the effects of Sn and Mo contents on electrochemical behavior and phase analysis of Ti12Mo23Sn (wt.%) and Ti23Mo12Sn (wt.%) alloys for biomedical applications. The samples were manufactured by blended combining the elemental method from a sequence of uniaxial and cold isostatic pressing with subsequent densification by sintering at 1000°C, in protective gas atmosphere. The corrosion resistance of the studied alloys in Ringers solution were determined. The structural properties were examined by scanning electron microscopy (SEM + EDS) and X-ray diffraction (XRD). X-ray phase analysis shows two phases: β-Ti and Ti3Sn for both samples. The proposed quantitative composition of the tested samples was confirmed in the chemical analysis. The results of the electrochemical analysis reveal that the open circuit potentials recorded for the Ti12Mo23Sn and Ti23Mo12Sn samples were quite similar. Moreover, obtained results indicate that the titanium alloy composed of 23 wt.% of Mo and 13 wt.% of Sn exhibited slightly better corrosion resistance than the Ti12Mo23Sn sample with lower concentration of Mo (12 wt%) in the Ringer`s solution.