Showing 26 results for Nanocomposite
M. Maniei, A. Eshaghi, A. Aghaei,
Volume 38, Issue 2 (9-2019)
Abstract
In this research, MgF2-2%SiO2/MgF2 thin films were applied on a glass substrate. At first, MgF2 thin films with the optical thickness were deposited on the glass slide substrates. Then, MgF2-2%SiO2 thin films were deposited on the glass coated with MgF2 thin films. Finally, the nanocomposite thin films were surface treated by the PFTS solution. Characterization of the thin film was done by X-Ray defractometry (XRD), attenuated total reflectance fourier transform infrared spectroscopy (ATR-FTIR), UV-Vis spectroscopy, and atomic force microscopy (AFM) techniques. Also, the hydrophobic properties of the samples were investigated by measuring the contact angle of the water. The results showed that the deposition of the six layer MgF2 thin films on the two sides of the glass substrate increased the transmission up to 96.4%. For the glass deposited by MgF2-2%SiO2 nanocomposite thin films, transmission was reduced to 94.4%, with its transmission being higher than the pure glass. Also, the water contact angle (WCA) analysis determined that the contact angle of the water droplet on the MgF2-2%SiO2 nanocomposite thin film coated glass was decreased. On the other hand, the contact angle of the water droplet on the MgF2-2%SiO2 nanocomposite thin film coated glass after modification with the PFTS solution was increased up to 119o. So, MgF2-2%SiO2 nanocomposite thin films could be used as an antireflective and self-cleaning coating on the surface of the optical devices.
N. Zakeri, H.r. Rezaie, J. Javadpour, M. Kharaziha,
Volume 39, Issue 4 (2-2021)
Abstract
In recent years, nanoceramics have been used in scaffolds to emulate the nanocomposite with a three-dimensional structure of natural bone tissue. In this regard, polycaprolactone biopolymer is widely used as a scaffold in bone tissue engineering. The goal of this research is to produce porous scaffolds of polycaprolactone - zeolite biocomposite with suitable mechanical, bioactive and biological properties for bone tissue engineering applications. The nanocomposite scaffolds were synthesized by solvent casting/particulate leaching and freeze-drying approaches. Microscopic investigations showed generation of pores with an average size of 200-400μm after addition of ceramic phase. Energy dispersive X-ray analysis confirmed uniform distribution of ceramic phase in polycaprolactone matrix. FTIR results determined the binding type of zeolite nanoparticles to the polycaprolactone matrix as physical bonding. The results of mechanical tests showed the increase in young’s modulus after addition of ceramic phase (from 0.04 to 0.3 and 3 to 7 MPa, respectively). The hydrophilicity of polycaprolactone increased after adding nanozeolite and more weight loss was observed for scaffold containing 20% zeolite (53.52 6 1.6%) with an increase in the rate of hydroxyapatite formation. The results showed that the prepared scaffolds have potential for cancellous bone tissue engineering application.
I. Forooghi , M. Mashhadi,
Volume 39, Issue 4 (2-2021)
Abstract
Due to their unique features, Ultra-High Temperature Ceramics (UHTCs) have potential applications in aerospace, military and industry. ZrB2-SiC composite as one of these ceramics has been at the center of researches due to its attractive mechanical, thermal and oxidation resistance. In this study, the effect of ZrC addition on pressureless sintering behavior, mechanical, microstructural and thermal properties of ZrB2-SiC nanocomposite were investigated. For this purpose, micron-sized ZrB2 and ZrC powders and nano-sized SiC powder were used. ZrB2-20vol% SiC nanocomposites with addition of (3, 6, 9, 12, 15) vol% ZrC were sintered by pressureless sintering method at 2100 ºC. The results showed that the addition of ZrC improved relative density, hardness and fracture toughness of ZrB2-20vol% SiC nanocomposite. Optimum properties were obtained in a sample containing 12 vol% ZrC and the relative density, hardness and fracture toughness of this sample were reported to be 99.01%, 16.95 Gpa and 5.43 Mpa.m0.5, respectively. Thermal analysis of the samples showed that by adding ZrC, thermal diffusivity of this nanocomposite reduced. The highest thermal diffusivity at room temperature equaled 35.3 mm2 /s and was obtained for ZS composite.
S. Borhani Esfahani, H. R. Salimi Jazi, M. H. Fathi, A. Ershad Langroudi, M. Khoshnam,
Volume 40, Issue 1 (5-2021)
Abstract
In this research, a kind of environmentally-friendly inorganic-organic hybrid nanocomposite coating based on silica containing titania/silica core/shell nanoparticles was synthesized and characterized for conservation of facade tiles in historical buildings. The matrix of the composite was prepared by sol-gel process via two methods of ultrasonic and reflux stirring. Tetraethyl orthosilicate (TEOS) and poly-dimethyl siloxane hydroxy-terminated (PDMS-OH) were used for the formation of silica network and creation of flexibility and hydrophobicity, respectively. Titania nanoparticles were used in the form of titania/silica core/shell as ultraviolet absorber. The synthesized nanocomposite was applied on the microscope slides and tiles by dip coating technique. The properties of nanoparticles and coatings were characterized by Fourier-transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and water contact angle measurement. The results revealed that formation of titania/silica core/shell structure was successful. The investigation of PDMS content effect on transparency, cohesion and hydrophobicity of the coating confirmed that the optimum content of this siloxane was around 20 wt.%. In general, the results showed that the silica-based hybrid nanocomposite reinforced with TiO2/SiO2 core/shell nanoparticles could produce a transparent and hydrophobic coating for tile and glass protection.
R. Zarei, E. Mohammadsharifi, M. R. Loghman, M. Ramazani, Kh. Zamani,
Volume 41, Issue 1 (8-2022)
Abstract
The present research has examined the effect of adding Si3N4 on the mechanical and structural properties of NiCrAlY alloy. The structural and mechanical properties of the manufactured samples were characterized by SEM, XRD, micro-hardness evaluation and pin on disk wear test. Various concentrations of Si3N4 powder (1, 3, and 5 wt.%) were mixed with NiCrAlY powder using a mechanical ball mill. Next, the mixtures were sintered at 1100 °C using the spark plasma sintering (SPS) technique. The XRD patterns indicated that the samples were composed of two phases of solid solution γ-Ni(Cr) and intermetallic compounds β-NiAl. The results of micro-hardness measurements showed that adding 1% Si3N4 to NiCrAlY enhanced the hardness from 418 to 614 HV. However, with an increase in the Si3N4 content from 1 to 5 wt%, the hardness diminished from 614 to 543 HV, and by Adding Si3N4 to the NiCrAlY, its tribological properties were significantly improved.
A. Azimi-Fouladi , S.a. Hasanzadeh-Tabrizi,
Volume 41, Issue 2 (11-2022)
Abstract
Water pollution is one of the big problems of human societies, and the need to find new ways to remove these pollutants has been given much attention in recent years. One of the methods is the use of photocatalysts. In this research, TiO2 and TiO2-CdO nanoparticles were prepared by a sol-gel method as nano photocatalysts. The produced samples have been used to degrade methylene blue under UV light. To characterize the prepared samples, X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), X-ray Energy Diffraction Spectroscopy (EDS), and Ultraviolet-Visible Spectroscopy (UV-Vis) were used. Microstructural results revealed nanoparticles with dimensions of 18 to 32 nm. XRD results showed that the main phase formed was the anatase. TiO2-4 wt.% CdO nanocomposite showed more photocatalytic activity compared to pure TiO2. Also, the effect of pH, irradiation time, and amount of powder on photocatalytic activity was investigated. The results showed that at pH=9, time of 75 min, and using 0.02 g TiO2-4 wt.% CdO photocatalyst, the maximum photocatalytic activity of about 92 % was obtained.
