[en] Highlights: • We study the flexural behavior of anodic oxide layers formed on aluminum. • Three and four-point bending tests were used as techniques. • Changing the beam configuration will change the flexural response. - Abstract: In this work, three and four-point bending tests were adopted as methods for characterizing anodized aluminum beams in a sulfuric acid bath. The failure behavior of sandwich beams having aluminum oxide face sheets and aluminum core were tested. In so doing, many configurations were adopted by anodizing aluminum beams on one and both sides to investigate faces in place of tension and compression. Bending tests showed different behaviors. When the oxide was only on the top side of the beam (working in compression) a slight sudden decrease of the load was observed. This fact was absent on beams with oxide layers working in tensile. The bending behavior of sandwich beams was similar to those with oxide on top sides but with much higher loads. The mechanical failure of the oxide was mainly caused by its failure when it is placed in compression beneath the loading rollers. Finally, a morphological study of the aluminum oxide layers after bending tests was conducted by optical microscopy

[en] Coatings of ZrSi/Zr₂Si on zirconium were prepared by deposition of silicon from monosilane on heated zirconium samples. The oxidation of these coatings by oxygen or water vapour follows the general rate law (Δm)sup(n) = kt (n approximately = 1.6). These kinetic results can be explained by the existence of two different silicide layers. At the lowest water vapour pressures, the kinetic behaviour is different; the formation of volatile SiO can account for this phenomenon. The experiments have shown the good corrosion resistance of this coating compared with that of pure zirconium. For example, in oxygen atmospheres the weight gains are about eight times less for silicides than for zirconium. (author)

[en] The kinetics of oxidation by water vapor of zirconium nitride and zirconium carbonitride coatings formed on zirconium have been followed respectively between 500 - 700⁰C and 500 - 600⁰C. The influence of the water vapor pressure has been investigated in the interval 0.2 - 20 Torr. The kinetic curves are similar to those observed with oxygen and can be interpreted by a mechanism involving the formation of zirconium-oxygen solid solutions preceding that of the zirconia. (Auth.)

[en] The synthesis and crystal structure of the bis (3-dimethylammonium-1-propyne) pentabromobismuthate(III) salt are given in the present paper. After an X-ray investigation, it has been shown that the title compound crystallizes at 298 K in a centrosymmetric monoclinic system, in the space group C₂/c with the following lattice parameters a=12.9034(3) Å, b=19.4505(6) Å, c=8.5188(2) Å, β=102.449(2). Not only were the impedance spectroscopy measurements of (C₅H₁₀N)₂BiBr₅ carried out from 209 Hz to 5 MHz over the temperature range of 318 K-373 K, but also its ac conductivity evaluated. Besides, the dielectric relaxation was examined using the modulus formalism. Actually, the near values of activation energies obtained from the impedance and modulus spectra confirms that the transport is of an ion hopping mechanism, dominated by the motion of the H⁺ ions in the structure of the investigated material.

[en] In the present work, the characteristics of thermoplastic polyurethane (TPU) material exposed to artificial weathering environment for different durations were studied. The influence on (i) appearance and morphology, (ii) thermal properties and (iii) mechanical properties evolution of the material were investigated during aging. For this purpose, ultraviolet (UV) chamber was used as accelerated aging technique. Optical and scanning electron microscopy (SEM) observations revealed changes in appearance and morphology of TPU material after UV-exposure. From differential scanning calorimetry (DSC) analysis, it was mainly found that thermal properties, in terms of glass transition temperature (T_g), were affected. Changes in mechanical behaviour were equally discerned using both computer-controlled tensile testing and abrasive wear tester. The mechanical properties in bulk of the studied material displayed tow steps. The elastic modulus and the stress at 200% of strain initially decreased and then increased progressively revealing an increase in crosslink density. The tribological properties, in terms of wear resistance, were affected and this degradation became more important with UV-exposure. Furthermore, our experimental results displayed prominently that there was a competition between chain scission and crosslinking mechanisms.

[en] Tin-zinc coatings offer excellent corrosion protection and do not suffer the drawback of the voluminous white corrosion product of pure zinc or high zinc alloy coatings. The aim of this study was to determine the suitable electroplating conditions (i.e. electrolyte composition and cathode current density) to produce 70Sn-30Zn electrodeposits. Thus, a fractional factorial design (FFD) was carried out to evaluate the effects of experimental parameters (Zn^II concentration, Sn^IV concentration, pH and current density) on the Zn content of the electrodeposit. On the other hand, the electrodeposits were characterised by glow discharge optical emission spectroscopy (GDOES) and scanning electron microscopy (SEM). Correlation between operating conditions, composition and morphology was attempted

[en] We described a three-step strategy to achieve simultaneous optimization of mechanical and chemical properties of an anodic aluminium oxide layer elaborated in a sulphuric acid solution. In the first two steps, a Doehlert design was carried out and then the canonical analysis has been conducted to study the four fitted models of the responses, namely: dissolution rate, Vickers microhardness, weight loss after abrasion and deflection at failure of the anodic oxide layer. Canonical analysis showed that the experimental conditions where the optima are found for each individual response are just opposite, so it is required to look for a certain compromise, which was achieved using the desirability function, in the last step. The morphology and the composition of 'optimum' layer was examined by scanning electron microscopy (SEM), atomic force microscopy (AFM) and glow-discharge optical emission spectroscopy (GDOES)