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Four different sensor devices were fabricated using the deposition of gold and nickel on top of polyaniline and polyaniline/zinc oxide composite thin films on glass substrates. Prepared samples were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy and UV-Visible spectroscopy. FESEM images confirmed the formation of interwoven nanofibers for all samples with the mean diameter of about 90 nm for PANI. The responses of the prepared samples toward various concentrations of ammonia gas were investigated by conductometric measurements at room temperature. The responses of the fabricated sensors toward 100 ppm of NH₃ were obtained to be 112%, 3%, 177% and 148% for PANI/Au, PANI/Ni, PANI/ZnO/Au and PANI/ZnO/Ni samples, respectively. Results show both Ni and Au thin films as a metallic catalyst on top of PANI/ZnO nanocomposite can greatly improve the sensing characteristics toward NH₃ at room temperature. However, PANI/ZnO/Au has the highest response with the lowest response time (4 s). The mechanism for the sensitivity enhancement of the fabricated devices was discussed.

The powder of the micro Al and variant volume fractions of nano Al₂O₃ were milled by a high energy planetary ball-mill. By milling, a homogenous distribution of nano Al₂O₃ particles in the metal matrix were developed. Then the milled powder was cold compressed and sintered at 545°C for one hr. The mold and the sintered sample hold in a furnace until the temperature reached 545°C. Then the hot 27mm diameter sample was extruded to 6mm diameter. From the extruded specimens, tensile, hardness and microstructure of the prepared specimens were determined. By these tests the effect of milling time, the percent of nano-particles and the microstructure were evaluated. The hardness and tensile behaviors of aluminum matrix composites reinforced with nano Al₂O₃ particulate have been found to increase remarkably with the volume fraction of the reinforcement.

In this investigation, TiN/TiB₂/TiAl nano-composite powder was produced by mechanical alloying technique and subsequent heat treatment. A powder mixture of Ti, BN, and Al with a molar ratio of 4:2:1 was milled for up to 70 h. Microstructures were studied and characterized using X-ray diffraction, scanning electron microscopy and energy-dispersive spectroscopy. The results indicated that TiN and TiB₂-based phases were formed in an amorphous Ti (Al) matrix after 30 h of ball milling. With progression of the milling, the amorphous Ti (Al) solid solution is partially crystallized and the particle size reduced significantly. Subsequent annealing of the milled product at 600 °C for 0.5 h resulted in the transformation of the unstable amorphous Ti (Al) to TiAl crystal structure and formation of TiN/TiB₂/TiAl nano-composite powder.

Self-organized nanocomposites of hydroxyapatite (HAp) and collagen were prepared by controlling temperature and pH on the basis of a biomimetic process. Transmission electron microscopic observations indicated that the composites prepared at pH 8-9 and 40°C had the bone-like structure in which the c-axes of HAp nanocrystals aligned along collagen fibers forming bundles of about 20μm in length and 1μm in diameter. The mechanical strength of the composites obtained was dependent on the degree of self-organization: the maximum 3-point bending strength was 39.5±0.88MPa and Young’s modulus 2.50±0.38GPa. When implanted in Wister rats’ craniums and beagles’ bilateral radii, osteoblasts and osteoclasts were induced near the composites after two weeks, and the composites were covered with a newly formed bone after 12 weeks.

Hydroxyapatite is the well known bioactive ceramic used in medical and dental fields as blocks and particles, while chondroitin-sulfate is a dominant polysaccharide component of cartilage. Novel composite materials consisting of hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂] and chondroitin-sulfate were synthesized by a coprecipitation method with a H₃PO₄ solution and a Ca(OH)₂ suspension, one of which contain chondroitin-sulfate, and were consolidated under a cold isostatic pressure. The composites were evaluated by X-ray diffractometry, Fourier transformed infrared spectroscopy and transmission electron microscopy. In the composites, hydroxyapatite nanocrystals contained calcium-deficiency and a small amount of carbonate ions like human bone minerals and their c-axes were aligned along chondroitin-sulfate molecules by a self-assembly mechanism.

Nano-sized hard materials have to be developed for improving mechanical properties. Nowadays, high energy mechanical milling (HEMM) method is widely used to fabricate nano-sized powders. The mechanical properties increase with decreasing grain size. However, grain growth has occurred by conventional sintering method with long sintering time. In this work, high-frequency induction heated sintering (HFIHS) was used to fabricate highly dense nano-sized WC-10vol.%Nicrobraz 30, 150 and LC composites for short sintering time without grain-growth. Therefore, control of grain growth during sintering is one of the keys to the commercial success of nano-structured cemented carbide composites. After sintering, relative density of WC-10vol.%Nicrobraz 30, 150 and LC composites were 99.9%, 98.7% and 98.0%, respectively. The grain sizes confirmed that full-width at half maximum (FWHM) was used from the result of XRD. The highly dense nano-sized WC-10vol.%Nicrobraz 30, 150 and LC composites were fabricated successfully using HEMM and HFIHS equipments.