Surface Composition Of Samples Research Articles

Characterisation of the bioactive behaviour of sol–gel hydroxyapatite–CaO and hydroxyapatite–CaO–bioactive glass composites

The fabrication and characterization of sol–gel derived hydroxyapatite–calcium oxide (HAp–CaO) material is investigated focusing on the effect of the addition of a bioactive glass on the material bioactive behaviour through the fabrication of a novel HAp–CaO (70 wt.%)–bioactive glass (30 wt.%) composite material. The bioactive behaviour of the materials was assessed by immersion studies in Simulated Body Fluid (SBF) and the alterations of the materials surfaces after soaking periods in SBF were characterized by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). A brittle and weakly crystalline carbonate hydroxyapatite (HCAp) layer was found to develop on the surface of all samples, few hours after immersion in SBF, confirming the high bioactivity of the material. Alterations of the morphology of the developed HCAp layer, which led to a more compact structure, were observed on the surface of composite samples after 7 days of immersion in SBF. The presence of the CaO phase seems to accelerate the formation of HCAp, while the bioactive glass affects both the morphology and cohesion of the developed layer.

Roentgen-phase investigation of monolithic titanium nitride

A method of synthesizing titanium nitride monolithic samples is described and the results of roentgen- phase investigation of the obtained material are presented. It is shown that, during nitridation, the sample surface composition changes and each stage of the process is characterized by an individual and specific set of phase states.

High-temperature oxidation of composites based on titanium carbonitride and double titanium-chromium carbide

The authors consider resistance to high-temperature oxidation in composite materials based on titanium carbonitride and double titanium-chromium carbide with metal binders, as well as titanium carbonitride with an aluminum nitride additive, with and without a binder. The oxidation resistance of double titanium-chromium carbide powders with a metal binder is studied in their initial and clad forms. Micro-x-ray-spectral and petrographic analysis is used to identify the composition of sample surfaces after oxidation.

The corrosion behavior of Zn coatings on Al-3103 alloy

Zinc films, 4 μm thick, were deposited on an Al–Mn alloy (Al-3103) plate using an ion beam-assisted deposition method. The corrosion behavior of the zinc coating samples was investigated in 0.1 M NaCl solutions in the presence and absence of bicarbonate/carbonate buffers. In the unbuffered NaCl solutions, both the Al-3103 and Zn/Al-3103 samples showed active dissolution, but Zn/Al-3103 had more negative corrosion potential and bigger corrosion current than the Al-3103 samples. In the buffered NaCl solutions, the Al-3103 samples showed passivation, while Zn/Al-3103 had a noble corrosion potential compared to the former. The surface compositions of samples, before and after zinc deposition, were checked using Rutherford backscattering spectroscopy. The surface chemical states for samples after corrosion were analyzed by means of X-ray photoelectron spectroscopy. The corrosion products were mainly zinc oxides, zinc hydroxides and aluminum oxides.

In-Situ Monitoring of the Initial Growth of a-C:H Films by AES

AbstractAmorphous hydrogenated carbon films are deposited by direct ion beam deposition onto Si and W substrates at room temperature. Simultaneously, the sample surface composition is measured by Auger electron spectroscopy. The results indicate a sharp interface between film and Si and the formation of a W2C layer between film and W. The in-situ measurements are compared with sputter depth profiles. It is found that the former ones give insight into film growth processes, that is unattainable by sputter profiling.