Search

High speed high pressure torsion (HSHPT) is a novel severe plastic deformation technique that is used to produce bulk ultrafine-grained nickel-titanium shape memory alloys. In this study, the effect of grain refinement on phase transformation was investigated in a near equiatomic NiTi shape memory alloy subjected to processing by this technique. Phase transformations involving different degrees of deformation and stability of thermally-induced phase transformations were analyzed by differential scanning calorimetry (DSC). The measurements suggest that the martensitic transformation occurred even when the highest degree of deformation was applied. Optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations bring to light that the true strain applied controls the evolution of the microstructure. The results are presented and discussed in detail in this paper.

Thermomechanical rolling (TMR or TMCP) is a special rolling process resulting in an extremely high-strength, fine-grained substructure which simultaneously offers very good toughness and cold formability. TM products have much lower carbon content and consequently are much less susceptible to cold cracks during welding. In ArcelorMittal Galati the challenge was to increase for structural steel the feasibility from 50 up to 80 mm and targeted plate thickness without ACC mode. Slabs thickness produced in AMG with maximum 250 mm thickness corresponding to almost the maximum ratio of 3:1 between slabs and targeted plate thickness according to the EN 10025/4/2004. TM rolled steels performed in industrial trial presented in this paper were performed in Heavy Plate Mill no 2 in ArcelorMittal Galați using computer process SIROLL assisted by AGC system. The main goal of this experimental rolling is to provide a concise and complete overview of the rolling process with higher amount of deformation below Tnr (non-recrystallisation temperature) and close to Ar3 in austenite region, and to address the potential to optimize it. [ABSTRACT FROM AUTHOR]

The paper discusses the challenges to develop thin films transistors for flexible transparent electronics, displays etc. The sol-gel preparation of hybrid thin films based on dielectric oxides nanoparticles (SiO2 NPs, ZrO2 NPs) and polymethy methacrylate (PMMA) is presented. The high-k hybrid thin films, evaluated as gate dielectric in a MIM structures, were deposed by spin-coating teqhnique. The multilayers (thin films) configuration of MIM structures were investigated by scanning electron microscopy (SEM) and electrical properties. The I-V and C-V curves showed a better dielectric behavior of hybrid films with respect to the simple PMMA films. Dielectric constant values of 2.1, 3.4 and 5.4 have been obtained for PMMA, ZrO2-PMMA and SiO2-PMMA films, respectively. [ABSTRACT FROM AUTHOR]

Homogeneous epoxy coatings containing ZrO2 nanoparticles were applied on Grade A naval steel substrates. The morphology of the coating was characterized by optical microscopy and scanning electron microscopy. The effect of nanoparticles on the corrosion resistance of the hybrid coating was investigated by potentiodynamic polarization method. ZrO2 (1wt. %) doping increased the microhardness of coating up to 15%, from 12.5 (kgf/mm2) to 14.4 (kgf/mm2). The coated steel samples were electrochemically monitorized over the 30 days of immersion in 5 wt. % NaCl solution. As shown by the polarization resistance and corrosion rate, the nanoparticles have a beneficial role, significantly improving the corrosion resistance. [ABSTRACT FROM AUTHOR]

The HfO2 thin-film is a very promising gate dielectric material for last generation transistors. The paper presents the thermal decomposition of hafnium ethoxide used as molecular precursor for obtaining hafnia thin films. The investigated molecular precursor is a mixture of Hf3O(OC2H5)10 and Hf4O(OC2H5)14 moisture sensitive amorphous powder. The thermal decomposition of hafnium ethoxide precursor was investigated by TG-DTG-DSC analysis from room temperature to 6000C in nitrogen atmosphere at 5K/min. The composition of gas products resulted during pyrolytic decomposition has been studied by Fourier Transformation Infrared Spectroscopy (FTIR) and Mass Spectroscopy (MS). In the gas products, hydrogen, methyl, ethyl, vinyl, hydroxyl groups, acetic aldehyde and acetylene were identified. From mass spectroscopy and FTIR data results that the loss of ethoxy groups from the molecular precursor occurs in the decomposition steps between 200 and 375oC. That suggests that in different steps, ligands from different coordination spheres are lost. [ABSTRACT FROM AUTHOR]

The approach for selective growth of 1D nanostructured oxide materials using poly (dimethylsiloxane) (PDMS) stamp consists of using microcontact printing, as such the soft lithography technique, for transferring the pattern of ZnO film on a substrate, followed by the hydrothermal growth of 1D nanowires on patterned areas. The nanowires have been grown in aqueous solutions of zinc nitrate at temperature at 95°C. The wettability of the glass and of the Si/SiO2 substrates was investigated by contact angle measurements. The morphology of the nanostructures obtained was characterized by optical microscopy and scanning electron micoscopy. [ABSTRACT FROM AUTHOR]

The preparation and structural characterization of titanium oxide nanowires as functional materials for the development of chemical sensors is presented in this work. The new types of materials for sensorics, aspects of material preparation relevant for gas sensing applications is presented .The functional characterization is focused on the detection of alcohols. Titanium oxide thin films prepared by solvotermalthermal method in highly alkaline conditions and the performance of 1D nanostructure is compared with mesoporous thin film prepared by sol-gel method. [ABSTRACT FROM AUTHOR]