New Achievements in Manufacturing of Church Bells

Analysis, modelling and design of the bells are a topical issue for manufacturers of bells, in general, and for church bells manufacturers in particular. The transition from manual design of a bell to that achieved with the computer led to  fabrication of bells capable to produce sounds of bells controlled close to those of musical instruments. It is mentioned a number of specialized software such as AUTODESK, for sizing profile of a bell; RESHAPE for analyzing and adjusting tones and WAVANAL for processing issued sound. The performances of a bell are closely related to the material used, casting technologies, possibly heat treatment and their grinding, processes that can be controlled automatically by computer

Preparation and Characterization of Tin Oxide Thin Films

Tin oxide (SnO) thin films were prepared onto glass substrates by thermal evaporation under vacuum. The substrate temperature was kept constant at 300 K during the film growth. The structural studies using transmission electron microscopy (TEM) analysis showed that the SnO thin films have a polycrystalline and tetragonal crystal structure with preferential orientation of (110) planes parallel to the substrate. Optical transmission and reflection spectra, at normal incidence, in the spectral range 300-1100 nm, are investigated. The optical properties of SnO thin films were determined. The optical energy band gap, Eg, has been estimated from the absorption coefficient values using Tauc’s procedure. It is found that the SnO thin films exhibit direct band gap

Copper Plating Corrosion Study in Certain Environments

Copper plating was performed on nickel substrate by means of the potentiostatic electrodeposition method from a sulphate electrolyte solution. The copper coatings morphology was studied by means of the optical and electronic scanning microscopy techniques. The uniform electrodeposited films have a thickness of about 15 µm measured in cross-section. The corrosion behaviours of nickel substrate and copper films in different corrosive environments were studied. The corrosion study was performed by means of the linear polarisation method in four acid environments: 0.5 M H2SO4, HCl, HNO3 and glacial CH3COOH. From the recorded Tafel curves it was possible to obtain some information about the corrosion rate and the polarization resistance. In order to confirm these results, the gravimetric parameter was calculated by means of the “mass loss” method. By means of the X-ray diffraction analysis, the crystallographic structure of the specimens before and after corrosion was revealed. By means of the spectrophotometer device, the optical properties of the specimens were analysed

Preparation and Characterisation of Alumina Template Obtained by OneStep Anodization Method

The goal of this study was to obtain an alumina template (AAO) by one-step anodization method and to evaluate its optical properties correlated with the annealing temperature. AAO was obtained from two different media: sulphuric acid (1.5 M H2SO4) and oxalic acid (0.4 M H2C2O4) at a potential of 15 V and 40 V, respectively. AAO morphology and chemical composition had been investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The average pore diameters such as 20 nm for AAO obtained from H2SO4 and 40 nm from H2C2O4 were measured. The crystalline structures of AAO samples annealed at three different temperatures of 150 ºC, 300 ºC and 350 ºC were studied by Xray diffractometry (XRD). The effect of annealing temperature on the optical properties of AAO was studied by UV-VIS spectrophotometry

Influence of Substrate Temperature on Structural and Morphological Properties of SnO2 Nanostructured Thin Films

SnO2 nanostructures thin films with thickness of 500 nm were prepared by electron beam-physical vapor deposition on glass substrate at temperature of 300, 373, 443, and 583 K. Structural and morphological properties of these nanostructured thin films were studied by Scanning and Transmission Electron Microscopy (SEM, TEM) and Atomic Force Microscope (AFM) methods. The changes in structural and morphological properties are found at different temperatures. Increase temperature causes important change of the structural and morphological properties. The sample prepared at 300 K has crystalline structure and the sample prepared at 583 K has amorphous structure. Roughness parameters have low values at 300, 373, 443 K as opposed to the values obtained at 583 K. This different behavior may be due to the amorphous structure of the sample that was observed in the TEM analysis

Study of Ni-TiO2 nanocomposite coating prepared by electrochemical deposition

Advances in materials performance often require the development of composite system. Nanocomposites containing titanium oxide nanoparticles in a nickel matrix have been prepared by means of electrocodeposition process from nickel plating bath an sulphate bath. The nanocomposite coatings were obtained by codeposition of the TiO2 nanoparticles (mean diameter 21 nm) with nickel during plating process. The surface morphology and microstructure of the nickel matrix was significantly altered due to the presence of titania nanoparticles. In the case of both nickel baths, the Vickers microhardness showed a tendency to increase with the amount of particle incorporation. The corrosion behaviour of the electrodeposited nickel in 0.5M Na2SO4 and 0.5M NaCl was studied using electrochemical methods. The corrosion rate calculated by polarization potentiodynamic curves obtained after 30 min and 1 h from immersion in solution is bigger for nanostructured coatings in 0.5M Na2SO4 (5.92 μm/year) and a little bit smaller in 0.5M NaCl (3.77 μm/year)

Electrocodeposition of Ag/TiO2 nanocomposite coatings in cyanide free electrolytes

Synthesis and characterisation of nanocomposite coatings consisting of Ag doped TiO2 nanocrystals at different concentrations have been carried out. Composites were obtained by electrochemical deposition using a slightly alkaline cyanide free electrolyte containing AgNO3 as Ag precursors. Morphology and crystalline structure of the Ag/TiO2 hybrid materials with up to 8?5 vol.-%TiO2 were compared with those of pure Ag coatings. The presence of TiO2 nanoparticles in the bath led to an increase in the degree of orientation of crystallites on [111] and [311] crystallographic directions. During the electrodeposition, the presence of TiO2 particles at the electrode/electrolyte interface retards the crystal growth, and hence, the composites possess smaller grain sizes. The surface morphology observations show that TiO2 nanocrystals were attached within the metallic matrix surface, and the appearance of the surface indicates a porous structure with different geometrically shaped grains; this is also confirmed by atomic force microscopy measurements