Volume 9 (2009): Issue 3 (September 2009)

The non-linear analytic-numerically computed calculations with use of two different heat source models are adopted for Pulsed Power Welding (PPW). The following heat source models are used in this study: cylindrical-involution-normal (C-I-N) and double-ellipsoidal (D-E). At first the temperature fields generated by C-I-N and D-E heat sources with pulsed power in both stationary and moving co-ordinates systems (Fourier transformation form) are established.

In order to execute computer calculations with temperature dependent physical parameters: λ, c_p, ρ, a and pulsed heat input q(t), the algebraic expression will be transformed. For this purpose we will use calculations in Mathcad programme [1]. This application is very useful for modelling and simulation of welding thermal process. Finally, the specifications of sub-procedures: Stab_time, last, calculation of roots r_i, λ(T), a(T) and q(t) are presented.

Characteristics of new nitrogen doped TiO₂ prepared in an one-pot synthesis where titania (IV) complexes with ligands containing nitrogen atoms were used as a precursor are presented in this paper. The pale yellow nanopowder with crystallite size of 9 - 12 nm is obtained as a product of calcination at 310°C and repeated washing procedure. Elemental analysis shows that nitrogen (1.087 at. pct.) is present in obtained material. The morphology and microstructure of samples were examined by XRD, AFM, UV-VIS and FTIR-ATR techniques. These studies confirm that obtained powder demonstrates a significant decrease in the band gap energy value (E_g = 2.83 eV) comparing to pure TiO₂ (E_g 3.22 eV). Presence of N-Ti-O bonds was confirmed via FTIR ATR. Products of the powder thermal decomposition were detected using TG-DSC technique coupled with mass spectrometry (MS). The report presents electrochemical studies which allow estimation of a flatband potential E_fb on the basis of the Mott-Schottky relation.

The surgical implants are made of different materials, such as cobalt alloys, titanium alloys and stainless steels. These materials contain little amount of carbon and significant amount of Cr, Ni and Mo. The metallic implants introduced into the human body undergo degradation mainly as a result of corrosion after a long use, due to aggressive biological impact between the implant surface and human body. This phenomenon is accompanied by the release of metal ions from implant surface, which gather in tissues surrounding the implant as well as the soft tissues (for eg. the liver).

Development of the optoelectronic system for non-invasive monitoring of diamond/DLC (Diamond-Like-Carbon) thin films growth during μPA ECR CVD (Microwave Plasma Assisted Electron Cyclotron Resonance Chemical Vapour Deposition) process is described. The system uses multi-point Optical Emission Spectroscopy (OES) and long-working-distance Raman spectroscopy. Dissociation of H₂ molecules, excitation and ionization of hydrogen atoms as well as spatial distribution of the molecules are subjects of the OES investigation. The most significant parameters of the deposited film like molecular composition of the film can be investigated by means of Raman spectroscopy. Results of optoelectronic investigation will enable improvement of CVD process parameters and synthesized DLC films quality.