Showing papers by "Sirus Javadpour published in 2016"

On the Gating Mechanism of Slippery Liquid Infused Porous Membranes

Abstract: Slippery liquid infused porous surfaces owe some of their remarkable properties such as low fouling, multiphase transport without clogging, and self-healing to the presence of liquid lined pores. In this paper, the gating mechanism of liquid infiltrated porous membranes is investigated. The liquid film thickness lining the pores is experimentally obtained and correlated to annular two phase flow models

Cyclic Oxidation and Hot Corrosion Behaviors of Gradient CoNiCrAlYSi Coatings Produced by HVOF and Diffusional Processes

Abstract: Conventional and gradient CoNiCrAlYSi coatings were produced using high-velocity oxy-fuel (HVOF) and an additional step of diffusional over aluminizing (pack cementation) techniques on the Inconel-738 substrate. Hot corrosion and cyclic oxidation performance of the conventional and the gradient coatings were investigated by exposing samples to a molten salt of Na2SO4–20 % wt. NaVO3 at 880 °C and 1-h exposure at 1100 °C in air. Corrosion and cyclic oxidation rates were determined by measuring the weight gain at regular time intervals. X-ray diffraction, field emission scanning electron microscopy, and electron probe microanalysis techniques were used to characterize the coatings and the thermally grown oxide. Increase in the amount of β aluminum-rich phase and the formation of high-chromium layer beneath the outer aluminum-rich layer and the low surface roughness of gradient coating increased the hot corrosion and oxidation resistance by a factor of 1.7. In addition, the gradient coating showed better rehealing of the thermally formed alumina scale due to its possession of more β phase as a Al reservoir.

Effect of Carbide Distribution on Corrosion Behavior of the Deep Cryogenically Treated 1.2080 Steel

Abstract: Deep cryogenic heat treatment is a supplementary process performed on steels specifically tool steels before tempering to improve the wear resistance and hardness of these materials. The carbide distribution changes via the electric current flow or the application of a magnetic field during the deep cryogenic heat treatment. Hence, the electric current and the magnetic field were applied to the samples to investigate the corrosion behavior of the deep cryogenically treated samples by electrochemical impedance spectroscopy and potentiodynamic polarization measurements. The results showed that increasing the carbide percentage and achieving a more homogenous carbide distribution during the deep cryogenic heat treatment will remarkably decrease the corrosion resistance due to a decrease in the solutionized chromium atoms in the structure as well as the increase in the martensite-carbide grain boundaries (the galvanic cell areas). Moreover, it was clarified that the electric current flow and magnetic fields reduce the carbide percentage, which leads to an increase in the corrosion resistance of these samples in comparison with the deep cryogenically treated samples.

Cryogenic heat treatment of the ferrous materials – a review of the current state

Abstract: Deep cryogenic treatment is a supplementary heat treatment which has been used industrially since the 70s in the last century. This process includes lowering the samples temperature down to that of the liquid nitrogen (–195 ◦ C), holding the samples at that temperature for some periods of time and then warming the samples gradually up to room temperature. This process is regularly used for different kinds of steels, including the HSS, tool steels, cast iron and carburized steels. This study attempts to clarify the effect of different environmental variables on the materials, subjected to the deep cryogenic heat treatment, as well as explaining the common theories about the cryogenic behavior of the ferrous materials.

Effect of Magnetic Fluid Hyperthermia on Implanted Melanoma in Mouse Models

Abstract: Background: Nowadays, magnetic nanoparticles (MNPs) have received much attention because of their enormous potentials in many fields such as magnetic fluid hyperthermia (MFH). The goal of hyperthermia is to increase the temperature of malignant cells to destroy them without any lethal effect on normal tissues. To investigate the effectiveness of cancer therapy by magnetic fluid hyperthermia, Fe0.5Zn0.5Fe2O4 nanoparticles (FNPs) were used to undergo external magnetic field (f=515 kHz, H=100 G) in mice bearing implanted tumor.Methods: FNPs were synthesized via precipitation and characterized using transmission electron microscopy (TEM), vibrating sample magnetometer, and Fourier transform infrared. For in vivo study, the mice bearing implanted tumor were divided into four groups (two mice per group), namely, control group, AMF group, MNPs group, and MNPs&AMF group. After 24 hours, the mice were sacrificed and each tumor specimen was prepared for histological analyses. The necrotic surface area was estimated by using graticule (Olympus, Japan) on tumor slides.Results: The mean diameter of FNPs was estimated around 9 nm by TEM image and M versus H curve indicates that this particle is among superparamagnetic materials. According to histological analyses, no significant difference in necrosis extent was observed among the four groups.Conclusion: FNPs are biocompatible and have a good size for biomedical applications. However, for MFH approach, larger diameters especially in the range of ferromagnetic particles due to hysteresis loss can induce efficient heat in the target region.

Designing and optimizing of composite and hybrid drive shafts based on the bees algorithm

Abstract: The main aim of this work is to introduce a novel approach to design and optimize of composite drive shafts based on Bees algorithm (BA). BA was performed on a specific filament wound composite drive shaft which was supposed to be installed in a cooling tower. Three different composite laminates were optimized by BA to evaluate their final mass to cost ratio. The laminates were Glass fiber reinforced epoxy (GFRE), Carbon fiber reinforced epoxy (CFRE) and a hybrid of them. The conduction of BA led to just one optimum output for GFRE and CFRE; however, a cost-mass diagram including various acceptable solutions was the end result for the hybrid drive shaft. At the end, the BA predictions of the lowest cost optimized hybrid drive shaft were compared with the results of ANSYS simulations.

Durable titania films for solar treatment of biomethanated spent wash

Abstract: The use of TiO2 films for treatment of biomethanated spent wash is reported. The films of TiO2 were formed and photocatalytic performance of the prepared films in degradation of methylene blue and biomethanated spent wash were studied. Photocatalytic use of these films was found to be effective for degradation of biomethanated spent wash. The photocatalyst was used up for 20 cycles without significant reduction in activities showing long life of the catalyst.

Investigating the effect of the deep cryogenic heat treatment on the corrosion behavior of the 1.2080 tool steel

Abstract: Deep cryogenic heat treatment is a supplementary process performed on a vast variety of materials, including tool steels, carburized steels, tungsten carbide, magnesium alloys, and polymers. This process improves the wear behavior and the working life of these materials. This study has investigated the effect of the deep cryogenic heat treatment on the corrosion behavior of the 1.2080 tool steel in different holding durations via the electrochemical impedance spectroscopy (EIS) and linear polarization test (TAFEL) in the environment of 3.5 wt.% NaCl aqueous solution. Results show that cryogenic heat treatment decreases the corrosion resistance of the tool steels as a consequence of increasing the carbide percentage as well as improving the carbide distribution. This phenomenon decreases the dissolved chromium atoms which are the major components in corrosion resistance of the tool steels. K e y w o r d s: 1.2080 tool steel, carbide distribution, corrosion resistance, deep cryogenic heat treatment

The effect of opacifiers on surface roughness ofceramic glazes

Abstract:                                                                                                                                                                                                                                                                                      