J.A. Kozubowski

Effect of calcium-ion implantation on the corrosion resistance and biocompatibility of titanium

This work presents data on the structure and corrosion resistance of titanium after calcium-ion implantation with a dose of 10(17) Ca+/cm2. The ion energy was 25 keV. Transmission electron microscopy was used to investigate the microstructure of the implanted layer. The chemical composition of the surface layer was examined 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. Biocompatibility tests in vitro were performed in a culture of human derived bone cells (HDBC) 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 calcium-ion-implanted and non-implanted titanium under the conditions of the experiment. As shown by TEM results, the surface layer formed during calcium-ion implantation was amorphous. The results of electrochemical examinations indicate that calcium-ion implantation increases the corrosion resistance, but only under stationary conditions; during anodic polarization the calcium-ion-implanted samples undergo pitting corrosion. The breakdown potential is high (2.7-3 V).

Effect of phosphorus-ion implantation on the corrosion resistance and biocompatibility of titanium

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.

SERPENTINE-SMECTITE INTERSTRATIFIED MINERALS FROM LOWER SILESIA (SW POLAND)

Interstratified serpentine-sm ectite was found in the fine-grained fraction of altered metasomatic contact biotite-schists developed between serpentinite and granite-type rocks (Lower Silesia ophiolite sequence, Poland). Ni-rich serpentine-smectite is R0-interstratified lizardite (0.80)-stevensite (0.15)-vermiculite-like (0.05), with a coherent scattering domain (csd) of 5 layers (mean value). The Mg-rich variety of serpentine-smectite is R1 lizardite (0.80)-stevensite (0.20) with a csd size of 7 layers (mean value). A transmission electron microscope study revealed complex layer relationships, with zones composed of various serpentine-smectite packets having lizardite/smectite ratios of 3:1, 2:1, 1:1, 4:1 and scarce serpentine segregations. In both cases, the serpentine-smectites appear to be late products of alteration of the parent biotite-schist.Experimental and calculated positions and intensities of reflections of the ethylene glycol-saturated, heated (250°C, thermal stage), and air-dried samples are in good agreement. Calculated X-ray diffraction patterns for interstratified glycolated and anhydrous serpentine-smectite are included in the Appendix.

Arc Plasma Synthesis of (Fe-Nd-B) - Containing Carbon Encapsulates

The formation of novel carbon nanostructures containing Fe-Nd-B nanocrystallites is reported. Tests were performed in a DC arc plasma reactor under He atmosphere using (Fe-Nd-B)- filled anodes. The influence of the operational parameters pressure and anode composition on the product morphology was studied. The products were analyzed by HR TEM, MFM and magnetic measurements. Emission spectroscopy was performed to determine the temperature and C2 radical distribution in the arc.

Implantation of silicon ions into a surface layer of the Ti6A14V titanium alloy and its effect upon the corrosion resistance and structure of this layer

The effect of silicon ion implantation upon the corrosion resistance and structure of the surface layers formed during the implantation in the Ti6A14V titanium alloy was examined. The silicon doses were 0.5, 1.5, 3.0 and 4.5 × 1017Si+/cm2, and the ion beam energy was 100 keV. The corrosion resistance of the samples exposed to a 0.9% NaCl solution at a temperature of 37 °C was measured using electrochemical methods. The structure of the surface layers formed during the implantation was examined by a transmission electron microscope (TEM). The results of the corrosion resistance examinations have shown that the unimplanted and 0.5 × 1017Si+/cm2 implanted samples undergo uniform corrosion. At higher silicon doses, the samples show pitting corrosion. The highest corrosion resistance was shown by the alloy implanted with 0.5 × 1017Si+/cm2. It has been found that, after a long-term (1200 h) exposure to a 0.9% NaCl solution, the corrosion resistance of the samples is greater than that observed after a short-term exposure. TEM examinations have shown that, beginning from a dose of 1.5 × 1017Si+/cm2, the surface of the Ti6A14V alloy samples becomes amorphous. Heating of the 1.5 × 1017Si+/cm2 implanted samples at 200 and 500 °C does not change their structure, whereas after heating at 650 °C, the amorphous phase vanishes.

Effect of oxygen implantation upon the corrosion resistance of the OT-4-0 titanium alloy

Abstract The properties of the surface layer on the OT-4-0 titanium alloy after oxygen implantation were examined. Polished samples were implanted with doses of 5 × 10 16 and 1 × 10 17 O + cm −2 . The O + ion energy was 50 keV. Transmission electron microscopy has been used to investigate the microstructure of the implanted layers formed on the OT-4-0. It was found that the implanted layers are nanocrystalline rutile (TiO 2 ). Depth profiles of oxygen and titanium were investigated by SIMS and corrosion resistance was analysed by electrochemical techniques. The results indicate that the oxygen implantation increases the corrosion resistance of the OT-4-0 titanium alloy.

The effect of tungsten addition on the magnetic properties and microstructure of SmFeN–α-Fe nanocomposites

Abstract The effect of tungsten addition, in the range of 0–17 at.%, on the magnetic properties and microstructure of SmFeN–α-Fe permanent magnet nanocomposites is presented. The magnets were prepared by mechanical alloying of elementary powders of Sm, Fe and W, followed by annealing and nitriding. The addition of tungsten leads to initial increase and further decrease of the coercivity with a maximum value of 250 kA/m for 7 at.% W. The remanence, however, continuously decreases from 1.2 T for 0% W down to 0.7 T for 17 at.% W. The maximum value of (BH)max, (120 J/m3), was obtained for 2 at.% W. The measurements of Curie temperature vs. W content showed a constant and decreasing values for α-Fe and the Sm2Fe17 phase, respectively. This behaviour can be explained by the dissolution of some W atoms in the Sm2Fe17 phase. X-ray diffraction analysis indicated, beside the α-Fe and Sm2Fe17 phases, the existence of pure W in the microstructure. Addition of W leads to reduction of the α-Fe crystallite size (20 nm for 0% W, 18 nm for 7% W and 8 nm for 17% W). The high resolution electron microscopy investigations show randomly distributed small (below 20 nm) crystallites of tungsten. Thus for a small amount of W the remanence is still substantially enhanced. The increase of the coercivity, for W contents up to about 7 at.%, can possibly be attributed to increased magnetic anisotropy of the Sm2(Fe,W)17N3 phase.

Effect of silicon-ion implantation upon the corrosion properties of austenitic stainless steels

The structure of the surface layers and the corrosion resistance of austenitic stainless steels after silicon-ion implantation, were examined. The implanted silicon doses were 1.5×1017, 3×1017 and 4.5×1017 Si+ cm-2. Implantation with all these doses gave an amorphous surface layer. When samples implanted with 1.5×1017 Si+ cm-2 were annealed at temperatures of 300 and 500 °C, their surface structure remained unchanged. After annealing at 650 °C, the amorphous layer vanished. It was determined how, in terms of corrosion resistance, the amount of implanted silicon, subsequent heat treatment and long time exposure, affect highly corrosion-resistant austenitic stainless steel (18/17/8) in comparison to the 316L austenitic stainless steel subjected to the same treatment. Corrosion examinations were carried out in 0.9% NaCl at a temperature of 37 °C. After silicon-ion implantation the corrosion resistance of the 316L steel increased while that of highly resistant (18/17/8) did not. The corrosion resistance of the investigated steels, both implanted and non-implanted, increased with the exposure time of the samples in the test environment.

Effect of silicon ion implantation on the properties of a cast Co–Cr–Mo alloy

The effect of silicon ion implantation upon the corrosion resistance and structure of the cast Co–Cr–Mo alloy of the Vitalium type, was examined. The silicon fluences were 1.5, 3.0 and 4.5 × 1017Si+ cm-2. The surface layer of the Vitalium samples implanted with these silicon doses was found to become amorphous. Further annealing of the samples at 200 °C resulted in the Cr3Co5Si2 phase being formed, whereas the amorphous layer was preserved. The Vitalium samples submerged in the 0.9% NaCl solution underwent mainly uniform corrosion, irrespective of whether or not they had been implanted with Si+ ions. With increasing doses of implanted silicon and after annealing at 200 °C (samples implanted with 1.5 × 1017Si+ cm-2), the corrosion resistance increased. The thickness of the oxide layer formed during the anodic polarization depended on the implanted silicon doses.

Encapsulates: Nd-Fe-B@C and Fe@C for Drug Delivery Systems and Contrast Elements, Study of Structure, Chemical Composition and Magnetic Properties

Encapsulates containing magnetic crystals are produced by the arcdischarge method. The functionalised magnetic encapsulates could be used in targeted drug delivery systems and as NMR contrast agents.