فصلنامه مواد پیشرفته و پوشش های نوین
پیاپی 13 (تابستان 1394)

Photodegradation due to weathering is the main decay of wood in many historical relics of Iran. Therefore, weathering of white poplar wood (Populus alba L.) and its treatments with UV absorber and hindered amine light stabilizer (HALS) was studied in order to conservation purposes. Samples artificially were weathered for 300 and 800 hours according to ASTM 2565-99. Mass loss of samples was measured and Colorimetery, ATR-FTIR spectroscopy and Scanning Electron Microscopy were used for evaluations. Results showed that lignin and then cellulose were decayed in untreated samples and degradation products have been leached. Treatments reduced the rate of degradation, but HALS treatment showed better efficiency against photodegradation and color change with compared to UV absorber treatment.

A series of potassium zinc phosphate (PZP) pigments were synthesized by a co precipitation method using different mole ratios of KOH:ZnCl2, and were investigated their inhibitive properties in this study.The morphology and phase composition of the pigments were studied by X-ray diffraction (XRD),Fourier transform infrared spectroscopy (FTIR)and scanning electron microscopy (SEM). The concentration of the ions released was measured by an inductivelycoupled plasma mass spectrometry (ICP). Also, the corrosion inhibition action of the pigment extract was studied bypolarization testthrough dipping steel samples in the solution containing extract for different immersion times.The results of X ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) revealed that the ratio of KOH:ZnCl2 significantly affected the phase composition, the shape and size distribution of the pigments. KZn2(HPO4)PO4 and KZnPO4 are the main phase recognized at low and high KOH:ZnCl2 ratio, respectively. Results showed a decrease in the corrosion current density of the steel panels immersed in the solutions containing PZPs for 24 h. In addition, it was found that PZPs with KZn2(HPO4)PO4 phase showed greater corrosion inhibition properties than those having KZnPO4 phase.

In this study, the surface of polypropylene nonwoven was grafted with acrylic acid. Oxygen plasma treatment was used to create the peroxide radicals required to initiate the grafting of acrylic acid onto the fibers. Several analyses including ATR-FTIR, FESEM, EDS, XPS and AFM were performed on raw, plasma treated and acrylic acid grafted samples. All tests approved the grafting of acrylic acid on the surface of polypropylene nonwoven. The prepared product (AA-PP) was tested for removal of cationic dye from aqueous media. AA-PP removed more than 70% of methylene blue cationic dye from water in pH=11. It was found that the dye adsorption followed Freundlich isotherm. The rates of sorption were found to conform to pseudo-first-order kinetics with good correlation.

This article is focused on a water based intumescent coating composed of potassium silicate binder. This coating included a bi-layer system. In order to evaluate the samples, a flame jet and a laser thermometer were used under laboratory conditions. Considering the obtained results, the samples were tested by TGA. Combination of silicate potassium resin (45 wt%) with acrylic-vinyl acetate resin intensified the foamie nature of carbon. The results obtained from the TGA testing showed that the combination compound incremented the weight resistance to 12.2% versus the thermal heating in interval of 20 500 o C.

One of the approaches for improving the protective performance of silane sol gel coatings is to optimize the application condition and parameters related to the silane solution. The aim of this study is to investigate the effect of aging time of silane solution and dipping duration in the silane solution on anticorrosion function of an eco-friendly hybrid coating applied on stainless steel 304L. The results of electrochemical impedance spectroscopy (EIS) clearly indicated that the barrier and protective properties of silane coatings were affected by variation of the two parameters. In order to study the morphology, topography and roughness of the hybrid coatings, atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) were used. The results of the electrochemical measurements and surface analysis revealed that that the most protective coating was obtained after 1 -s dipping of the metallic sample in the silane solution with no aging.

In this work preparation and optical characterize of SiO2-Na2O-CaO-CaF2–Cr2O3 glass and transparent glass-ceramic for optical host investigated and also the effects of substitute of 0.7 wt% CeO2 with Cr2O3 dopant in this properties determined. Glass samples was produced by melt-quenching procedure and then glass samples converted to transparent glass-ceramic by heat-treatment. According to XRD analysis glass ceramic doped with Cr2O3 and glass ceramic doped with Cr2O3-CeO2 contained nano-crystals of Ca4Si2O7F2 and Ca2SiO4, respectively. Also, electron microscope imags (SEM) well shows nano size structure in the glass-ceramic samples. Comparison each curve of photoluminescence and Uv-visible spectra of samples demonstrated that glass ceramic samples have high luminescence intensity because non-radiative relaxation of dopant ions will be decreased by crystallization in glass matrix. Furthermore, substitute of Cr2O3 dopant by CeO2 has provided best effect on luminescence property of glass-ceramics by energy transition between electron levels.

In this research, silver selenide (Ag2Se) quantum dots were synthesized via artificial atoms method and the effect of reaction ratio on the final structure was evaluated. The crystal phases, photophysical properties, morphology, and the stability of nanoparticles were investigated using comprehensive analyses such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR), UV-Vis optical absorption, and photoluminescence (PL) spectrometer. The XRD patterns revealed that the Ag2Se nanocrystals obtained from the ratio of AgN 3:Se,1.35:1, had Orthorohmbic structure with average crystallite size of 6.8 nm. Moreover, this sample also exhibited spherical particles with high shape uniformity, optical bandgap of 2.32 eV, and the good stability in 20:80, cyclohexane: chlorobenzene dispersion.