The surface layers were formed on titanium by plasma electrolytic oxidation (PEO) in the solutions which contain various amounts of Na(2)SiO(3)x5H(2)O, Na(3)PO(4) x12H(2)O and Ca(CH(3)COO)(2) xH(2)O. The layers were characterized using a scanning electron microscope (SEM) coupled with an energy dispersive spectrometer (EDS) and an X-ray diffractometer (XRD). The titanium/oxide surface layer interface was analyzed by X-ray photoelectron spectroscopy (XPS). The adhesive strength of the oxide layers was evaluated by the scratch-test. The bioactivity of the surface was determined by soaking in a simulated body fluid (SBF) for 7 and 30 days. The corrosion resistance was determined by electrochemical methods after 13, 181, and 733 h exposure in SBF at a temperature of 37°C. The oxide layers obtained were rough and porous and enriched with Ca, P, Si, and Na and their properties depended on the concentration of the components of the electrolyte. The results of the electrochemical examinations, after a 13 h exposure in SBF, show that the surface modification by PEO improves the corrosion resistance of titanium and it is not degraded after a long-term exposure in SBF. The electrochemical impedance spectroscopy (EIS) results indicate that the surface layers have a complex structure.

This paper is concerned with the surface modification of titanium by the PEO method (plasma electrolytic oxidation) in the solutions which contain Ca P Si and Na The chemical composition of the thus formed surface layers was examined by XPS and EDS The morphology of the surface was observed by SEM The phase composition was determined by X-ray diffraction (XRD) The adhesive strength of the oxide layers was evaluated by the scratch-test The corrosion resistance was determined in a simulated body fluid (SBF) at a temperature of 37 C by electrochemical methods for various exposure times The oxide layers obtained were porous and enriched with Ca P Si and Na and their properties depended on the electrolyte solution and the parameters of the oxidation process The results of the electrochemical examinations show that the surface modification by PEO does not worsen the corrosion resistance of titanium after a 13 h exposure in SBF The electrochemical impedance spectroscopy (EIS) results indicate that the surface layers have a complex structure and that their electric properties undergo changes during long term exposures in SBF (C) 2010 Elsevier B V All rights reserved

The paper presents the results of examinations of the corrosion resistance of titanium after its being subjected to the surface modification by the alkali- and heat-treatments. The material examined was commercially pure titanium (grade 2). The samples were soaked in an aqueous 10M NaOH solution at 60 degrees C for 24 h and subsequently heated at 500, 600, or 700 degrees C for 1 h. The chemical composition of the surface layers was determined by X-ray photoelectron spectroscopy and secondary ion mass spectroscopy. The phases present in the layers were identified by XRD. The corrosion resistance was evaluated by electrochemical methods (Stern's method, potentiodynamic method, and impedance spectroscopy) at a temperature of 37 degrees C after short- and long-time exposures. The 13 h exposure was aimed to allow the corrosion potential to stabilize. The aim of the long-term exposures was to examine how the corrosion resistance of the modified samples changes during the exposure. Under the conditions prevailing during the experiments, the highest corrosion resistance was achieved with the samples heated at a temperature of 700 degrees C.

This paper deals with the surface modification of titanium by sodium-ion implantation and with the effect of this modification on structure, corrosion resistance, bioactivity and cytocompatibility. The Na ions were implanted with doses of 1 × 10 17 and 4 × 10 17 ions/cm 2 at an energy of 25 keV. The chemical composition of the surface layers formed during the implantation was examined by secondary-ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS), and their microstructure—by transmission electron microscopy (TEM). The corrosion resistance was determined by electrochemical methods in a simulated body fluid (SBF) at a temperature of 37°C, after exposure in SBF for various times. The surfaces of the samples were examined by optical microscopy, by scanning electron microscopy (SEM-EDS), and by atomic force microscopy (AFM). Biocompatibility of the modified surface was evaluated in vitro in a culture of the MG-63 cell line and human osteoblast cells. The TEM results indicate that the surface layers formed during the implantation of Na-ions are amorphous. The results of the electrochemical examinations obtained for the Na-implanted titanium samples indicate that the implantation increases corrosion resistance. Sodium-ion implantation improves bioactivity and does not reduce biocompatibility.

The corrosion resistance and bioactivity of Ti6Al4V alloy after calcium-ion implantation were examined. Polished samples were implanted with a dose of 10(17) Na+/cm(2) at a beam energy of 25 keV. The chemical composition of the surface layer formed during the implantation was determined by XPS and SIMS. The bioactivity of the samples was evaluated by soaking them in a simulated body fluid (SBF) at 37 degrees C for 168 and 720 h. The corrosion resistance in SBF at 37 degrees C was determined by electrochemical methods after exposure in SBF for various times. The surfaces of the samples before and after examinations were observed by optical microscopy, SEM-EDS and AFM.The results of the corrosion examinations indicated that under stationary conditions and after short-term exposures, the calcium-ion implanted titanium alloy had an increased corrosion resistance, but during the anodic polarization, calcium-implanted samples underwent pitting corrosion. The microscopic observations show that the precipitations of calcium phosphates are present on the surface, but they do not form a continuous layer. (c) 2007 Published by Elsevier Ltd.

This paper is concerned with the surface modification of a cobalt alloy (Endocast) by sodium-ion implantation and with the effect of this modification on its corrosion resistance. The Na ions were implanted at doses of 1×1017 and 2×1017ions/cm2 at energy of 25keV. The chemical composition of the surface layers formed during the implantation was examined by secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS), and their microstructure by transmission electron microscopy (TEM). The corrosion resistance was determined by electrochemical methods in a simulated body fluid (SBF) at a temperature of 37°C. Prior to the measurements, the samples were exposed to the test conditions for 13h to allow the corrosion potential Ecorr to stabilize, and for 181, 733 and 2200h to investigate how the long-time exposures affect the corrosion resistance. The surfaces of the samples were examined by optical microscopy and by SEM-EDS. The TEM results indicate that the surface layers formed during the Na-implantation are amorphous. The results of the electrochemical examinations obtained for the Na-implanted Endocast samples indicate that the corrosion resistance of the alloy is reduced.

The corrosion resistance and bioactivity of titanium after sodium-ion implantation were examined. Polished samples were implanted with a dose of 1017 Na+/cm2 at a beam energy of 25keV. The chemical composition of the surface layer formed during the implantation was determined by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). The bioactivity of the samples was evaluated by soaking them in a simulated body fluid (SBF) at 37°C for 168 and 720h. The corrosion resistance in SBF at 37°C was determined by electrochemical methods after exposure in SBF for various times. The results obtained indicate that sodium-ion implantation improve the corrosion resistance after short-term exposures. During an exposure in SBF, calcium phosphates precipitate on the sample surface but they do not form a continuous layer.

This study is concerned with the effect of dual implantation of calcium and phosphorus upon the structure, corrosion resistance and biocompatibility of titanium. The ions were implanted in sequence, first Ca and then P, both at a dose of 10(17) ions/cm2 at a beam energy of 25 keV. Transmission electron microscopy was used to investigate the microstructure of the implanted layer. The chemical composition of the implanted layer was examined by XPS and SIMS. The corrosion resistance was determined by electrochemical methods in a simulated body fluid (SBF) at a temperature of 37 degrees C. The biocompatibility tests were performed in vitro in a culture of human-derived bone cells (HDBC) in contact with the tested materials. The viability of the cells was determined by an XTT assay and their activity by the measurements of the alkaline phosphatase activity in contact with implanted and non-implanted titanium samples. The in vitro examinations confirmed that, under the conditions prevailing during the experiments, the biocompatibility of Ca + P ion-implanted titanium was satisfactory. TEM results show that the surface layer formed by the Ca + P implantation is amorphous. The corrosion resistance of titanium, examined by the electrochemical methods, appeared to be increased after the Ca + P ion implantation.

The paper compares the effects of various surface modifications, ion implantation, alkaline treatment and anodic oxidation, upon the corrosion resistance and bioactivity of titanium. The chemical composition of the surface layers thus produced was determined by XPS, SIMS and EDS coupled with SEM. The structure of the layers was examined by TEM, and their phase composition by XRD. The corrosion resistance was determined by electrochemical methods after the samples were exposed to the test conditions for 13 h. The bioactivity of titanium was evaluated in a simulated body fluid at a temperature of 37 degrees C after various exposure time.

This study is concerned with the modification of titanium surface by plasma electrolytic oxidation (PEO) and hydrothermal treatment. The samples were oxidized in an electrolytic solution that contained calcium β-glycerophosphate and calcium acetate. Then, the specimens were hydrothermally heated at a temperature of 220°C for 4h using an autoclave. The chemical composition of the surface layers was examined by XPS. The morphology of the surface was observed by SEM-EDS. The crystalline phases were identified by XRD. The corrosion resistance was determined by the electrochemical methods in a simulated body fluid (SBF) at a temperature of 37°C after various times of exposure in SBF. The oxide layers formed by PEO were porous, highly crystalline and enriched with Ca and P. After hydrothermal treatment, hydroxyapatite crystals precipitated on the surface. The results of electrochemical examinations show that the surface modification by PEO and hydrothermal treatment decreases the corrosion resistance of titanium.

The paper presents the results of examinations of how the oxidation of titanium in a solution containing calcium and phosphorus ions affects the corrosion resistance and bioactivity of titanium. Prior to examination, the samples were exposed in the simulated body fluid (SBF) at the temperature of 37°C for 13 and 1000h. Then the corrosion resistance was examined by electrochemical methods in SBF at a temperature of 37°C. The chemical composition of the surface layers was determined by photoelectron spectroscopy (XPS). The examinations have shown that after the oxidation the corrosion resistance increases. After long-term exposures, calcium phosphates were found on the sample surface, and their amount was bigger on the oxidised surfaces.

The paper presents the results of examination of the properties of the layers enriched with calcium and phosphorus produced by the ion beam assisted deposition (IBAD) method. Transmission electron microscopy (TEM) was used to investigate the microstructure of the surface layers. The chemical composition of the layers was examined by the secondary ion mass spectrometry (SIMS) and Rutherford backscattering (RBS). The corrosion resistance was measured electrochemically in a simulated body fluid (SBF) at a temperature of 37°C. Prior to the measurements, the samples were exposed to the test conditions for 13 or 1000 h. A SIMS analysis indicates that the layers formed on titanium and the Ti6Al4V alloy contain calcium, oxygen and phosphorus. TEM results show that the surface layers have an amorphous structure, irrespective of the substrate and the kind of the auxiliary target. Corrosion resistance of the surface layers depends on the time of exposure in SBF.

This work presents the results of investigation of the bioactivity and corrosion resistance of titanium after phosphorus-ion implantation (dose 1×1017P+/cm2 and energy 25keV) and anodic oxidation in a 1.5M H2SO4 solution. The composition of the surface layers was investigated by XPS and SIMS. The corrosion resistance was examined by electrochemical methods in a simulated body fluid (SBF) at a temperature of 37°C. The results of electrochemical examinations indicated that the oxidation increased the corrosion resistance. The microscopic observations of the samples exposed to SBF revealed the presence of precipitates of calcium phosphates as confirmed by XPS.

This work presents data on the structure and corrosion resistance of titanium after phosphorus-ion implantation with a dose of 10(17)P/cm2. The ion energy was 25keV. Transmission electron microscopy was used to investigate the microstructure of the implanted layer. The chemical composition of the surface layer was examined by X-ray photoelectron spectroscopy and secondary ion mass spectrometry. The corrosion resistance was examined by electrochemical methods in a simulated body fluid at a temperature of 37 C. Biocompatibility tests in vitro were performed in a culture of human derived bone cells in direct contact with the materials tested. Both, the viability of the cells determined by an XTT assay and activity of the cells evaluated by alkaline phosphatase activity measurements in contact with implanted and non-implanted titanium samples were detected. The morphology of the cells spread on the surface of the materials examined was also observed. The results confirmed the biocompatibility of both phosphorus-ion-implanted and non-implanted titanium under the conditions of the experiment. As shown by transmission electron microscope results, the surface layer formed during phosphorus-ion implantation was amorphous. The results of electrochemical examinations indicate that phosphorus-ion implantation increases the corrosion resistance after short-term as well as long-term exposures.

The aim of the study was to find whether the basic phenomena that occur during the glow discharge assisted nitriding of metal differ from those occurring during gaseous nitriding. To define the specificity of a glow discharge assistance a simple model system such as an iron cathode nitrided in d.c. glow discharge in nitrogen at a low temperature was examined. The Fe4N layer of thickness 0.8 μm and 1.5 μm was produced in 5 h at 275°C and 3 h at 350°C, respectively. The results were compared with experimental data of gaseous nitriding and computer aided simulations based on the Lehrer (NH3–H2)1.5(Fe–N) equilibrium diagram. The thickness of the Fe4N layer produced in our experiment was greater than the thickness of the Fe4N layer produced in the gaseous process observed experimentally and as the estimated values from the model based on the equilibrium diagram, in spite of the fact that the total number of N atoms in the gaseous process was 40÷80 times greater than in the glow discharge assisted process. Based on the relation ΔN=k√Dt we proposed that the difference between the gaseous nitriding process and the glow discharge assisted nitriding process results from the difference in the values of k, which in turn depend on the N level at the diffusion front. The higher N level can be explained in terms of a shallow ion implantation.

This work presents the data on the corrosion resistance of titanium after Ca and/or P ion implantation with a dose of 1017/cm2. The Ca+, P+ ion energy was 25keV. The corrosion resistance was examined by electrochemical methods in a simulated body fluid at a temperature of 37°C. TEM was used to investigate the microstructure of implanted layers. The chemical composition of the surface layers was examined by XPS and SIMS. The results of electrochemical examination indicate that the P and Ca+P ion implantation into the surface of titanium increases its corrosion resistance. Samples implanted with Ca showed pitting corrosion during anodic polarization. The breakdown potentials were high (2.5–3V).

This paper is concerned with the corrosion resistance and biocompatibility of titanium after surface modification by the ion implantation of calcium or phosphorus or calcium + phosphorus. Calcium and phosphorus ions were implanted in a dose of 10(17) ions/cm(2). The ion beam energy was 25 keV. The microstructure of the implanted layers was examined by TEM. The chemical composition of the surface layers was determined by XPS and SIMS. The corrosion resistance was examined by electrochemical methods in a simulated body fluid (SBF) at a temperature of 37 degrees C. The biocompatibility was evaluated in vitro. As shown by TEM results, the surface layers formed during calcium, phosphorus and calcium + phosphorus implantation were amorphous. The results of the electrochemical examinations (Stern's method) indicate that the calcium, phosphorus and calcium + phosphorus implantation into the surface of titanium increases its corrosion resistance in stationary conditions after short- and long-term exposures in SBF. Potentiodynamic tests show that the calcium-implanted samples undergo pitting corrosion during anodic polarisation. The breakdown potentials measured are high (2.5 to 3 V). The good biocompatibility of all the investigated materials was confirmed under the specific conditions of the applied examination, although, in the case of calcium implanted titanium it was not as good as that of non-implanted titanium.