Search

A compact setup for in situ solvothermal vapor annealing of thin polymer films in the temperature range from room temperature to 70 °C is presented. The design is optimized to avoid solvent condensation in tubes and other components. The setup consists of a chamber, a gas delivery system, a commercial film-thickness measuring device, and a solvent vapor concentration sensor. The chamber is equipped with heaters and thermometers and is thermally insulated. It has windows to allow for penetration of xrays together with a sample table with a gas distributer to ensure homogeneous swelling of the polymer film. The computer-controlled gas delivery system has two different components, which can be used separately or in parallel (for mixed gas solvent annealing): (a) mass flow controllers and a bubbler system and (b) a commercial "controlled evaporation and mixing" system. The film-swelling ratio is determined in situ using optical reflectometry, and the solvent concentration in the exhaust gas is continuously monitored by UV-absorption. Test results are presented where the setup is used for swelling of ∼100 nm thick polystyrene and polyisoprene homopolymer films with toluene and acetone, respectively. [ABSTRACT FROM AUTHOR]

Nanostructure yttria-stabilized zirconia (nano-YSZ) /Al2O3 composite coatings were deposited on Inconel super-alloy substrates by electrophoretic deposition. Aluminum and nano-YSZ particles were utilized for reaction bonding at high temperatures. After aluminum oxidation at 650℃, sintering process was carried out at temperature ranges of 1100–1250℃. It was found that the presence of aluminum in the green coatings improves bonding and also compensates for the coatings’ volume shrinkage during sintering. The average crystallite sizes for all sintering temperatures were laid on a nanometric scale. Crystallite sizes of various YSZ/Al2O3 nanocomposite coatings were calculated via Scherer’s formula and the measures were in a reasonable agreement with the field-emission scanning electron microscopic results. The average grain size increased from 52.4 nm at 1100℃ for YSZ, to 68.3 nm at 1250℃ for YSZ/Al2O3 nanocomposite coatings. The nanocomposite coatings, which sintered at 1250℃ for 4 h exhibited an optimized self-crack healing capacity with lesser microcrack content. [ABSTRACT FROM AUTHOR]

In this paper, (SrFe 12 O 19 and NiFe 2 O 4 ) nanostructure ferrite particles were synthesized via the co-precipitation of chloride salts utilizing the sodium hydroxide solution. The resulting precursors were heat-treated at 1100 °C for 4 h. After cooling in the furnace, the ferrite powders were pressed at 0.1 MPa and then sintered at 1200 °C for 4 h. The spectroscopy and characterization of peaks at the microwave range (X-band) for the nanostructure ferrite particles were investigated by the ferromagnetic resonance/transmit-line theories and Reflection Loss (RL) plots. The extracted data from these theoretical and experimental results showed that the natural ferromagnetic resonance can be lead to the narrow peaks and the width of the peaks can be related to the periodic effects. Two kinds of peaks were seen for NiFe 2 O 4 at X-band (8–12 GHz); the narrow peak at (9.8 GHz) was remaining unchanged and consistent while the wide one was shifted from 11 GHz to 8.5 GHz by decreasing the thickness of the samples. These phenomena were also happened for SrFe 12 O 19 samples. The natural resonance was not happened due to the hard magnetic properties of these nano structure particles. [ABSTRACT FROM AUTHOR]

In the present study, central composite algorithm was used in order to model and optimize the mechanical behavior of "glass fiber reinforced epoxy composite - structural steel "connections. Initial tests showed that the polymer curing variables play a significant role as key process parameters in producing strong and reliable connections. After conducting Thermal Gravimetric Analysis on polymer, by selecting curing time and curing temperature as input variables, the parameters were coded and each of them was studied in five levels. In order to estimate the desirable response and provide appropriate models, thirteen tests were conducted systematically. In order to assess the accuracy and to validate the proposed model, analysis of variance was performed successfully. The effect of curing time and curing temperature on the connection's strength quality was studied utilizing two-dimensional graphs. Utilizing this approach the optimal bonding process variables was achieved at 40°C and 180 min for curing temperature and curing time respectively. Finally, the results obtained from micro structural characterization and fractography analyses of joints by Optical and Scanning Electron Microscope were in good agreement with the results achieved by the developed model. [ABSTRACT FROM AUTHOR]