Characterization of Diamond: Like Carbon Films Synthesized by DC-Plasma Enhanced Chemical Vapor Deposition

In this paper, diamond-like carbons were produced on tungsten and aluminum substrates by DC plasma enhanced chemical vapor deposition (DC-PECVD) system in a C₂H₂/H₂ gas mixture using C₂H₂ as source hydrocarbon and H₂ as etching and diluting gas. The operation pressure during the growth and substrates temperature were 15 Torr and 180°C, respectively. Characterization of the DLCs deposited on tungsten and aluminum substrates were carried out by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Raman spectroscopy and Atomic force microscopy (AFM). AFM analysis displayed that the DLCs grown on W substrate has lower roughness than the DLCs deposited on Al substrate and it was smoother. FTIR analysis indicates the existence of C–H vibration mode in the DLCs grown on both of substrates. The Raman spectroscopy shows G peak position and I(D)/I (G) ratio decreased for the DLCs grown on W substrate. The SEM images show diffuse and dense distribution of DLCs in Al and W substrate, respectively. These results shows that the optimum conditions were obtained on W substrate.     

Process Intensification by Exploiting Diluted 2nd Generation Bio-ethanol in the Low-Temperature Steam Reforming Process

Second generation bioethanol, obtained by the fermentation of lignocellulosic biomass, which is not competitive with the food and feed field, is one of the most interesting promising biofuels, already available in semi-commercial amount. Steam reforming of bioethanol has been used here for sustainable hydrogen and syngas production. Differently purified second generation bioethanol feeds, directly supplied by an industrial plant, for the steam reforming process, assessing the influence of impurities and catalyst formulation. Ni/La₂O₃, Ni/ZrO₂ and Ni/CaO–ZrO₂ prepared by Flame Spray Pyrolysis were used as catalysts. Catalytic performance at high and low temperature was evaluated in order to investigate a broad range of temperature, which is one of the most critical condition in term of catalyst activity and deactivation, besides energy saving. The possible effect of impurities contained in less purified feedstocks is also discussed. Stable performance up to 100 h-on-stream was attained even under stressing reaction conditions.     

Effect of annealing process on IR transmission and mechanical properties of spark plasma sintered Yttria

In this study, fully dense Yttria ceramics were successfully fabricated by spark plasma sintering (SPS) at temperatures of 1300 and 1350 $℃$. The effects of post-annealing on IR transmission were investigated by Fourier transform infrared spectroscopy (FTIR) at various temperatures ranging from 1050 to 1250 $℃$. It was found that the optimum annealing temperature depends strongly on the sintering temperature. Annealed samples showed white opaqueness mainly due to the increase and coalescence of pores after annealing and showed an absorption band around 6.6 $\mu m$ which limits usage of yttria in IR applications. Sintering at 1350 $℃$ and annealing at 1250 $℃$ led to the maximum IR transmittance above 80% at wavelength of 5 $\mu m$ for a 3.5-mm-thick sample. The hardness and the fracture toughness of the samples were analyzed in detail and hardness of 9.2 GPa and fracture toughness of 1.65 MPa m^1/2 were obtained for the above sample.     

An investigation of the reasons for non-compliance with FAR regulations in Tehran

The majority of the Tehran metropolitan region’s problems are associated with building contraventions, which intensified after migration from other parts of the country to the region increased. This migration coincided with a boom in the construction sector and an increase in density selling by the Tehran municipality.