Showing 11 results for Solution
A. Moosavi, A. Aghaei,
Volume 5, Issue 2 (6-2008)
Abstract
Abstract: Auto-ignited gel combustion process has been used for producing a red hematite-zircon
based pigment. The combustible mixtures contained the metal nitrates and citric acid as oxidizers
and fuel, respectively. Sodium silicate (water glass) was used as silica source for producing zircon
phase. X-Ray Diffractometery, Electron Microscopy and Simultaneous Thermal Analysis were used
for characterization of reactions happened in the resulted dried gel during its heat-treatment.
L* a* b* color parameters were measured by the CIE (Commission International de I'Eclairage)
colorimetric method. This research has showed that solution combustion was unable to produce
coral pigment as the end product of combustion without the need for any further heat treatment
process.
M. Farhani,, M. Soltanieh, M. R. Aboutalebi,
Volume 5, Issue 3 (9-2008)
Abstract
Abstract: Dissolution and recovery of Mn-Al compacts with and without a chloride flux was
studied by taking samples from the melt after addition of the compact. Events occurring after the
addition of the compacts into the melt were studied using water quenched specimens after holding
them for a specified time in molten state. The cross sections of these specimens were characterized
by SEM as well as optical imaging. The results showed that an optimized amount of flux (10 to
15%wt. in this research) considerably decreases the time to reach more than 90% recovery in
comparison with non-fluxed compacts. The flux caused the intermetallic forming reactions to be
started considerably sooner in fluxed compacts in comparison with the non-fluxed compact.
Consequently, the incubation time decreased from about 180 seconds for non-fluxed compacts to
less than 3 seconds for compacts with 10%wt. flux.
S.r. Allahkaram, R. Shamani,
Volume 6, Issue 1 (3-2009)
Abstract
Abstract: Due to the expansion of high voltage Alternating Current (AC) power transmission lines and cathodically
protected buried pipelines, it is becoming more and more difficult to construct them with enough safe distances
between them. Thus, the pipelines are frequently exposed to induced AC interferences, which result in perturbation of
Cathodic Protection (CP) due to AC corrosion. To study the above criterion, an experimental set up was used with
coupons exposed to simulated soil solutions, while under both CP and AC induced condition for which an AC+DC
power supply was utilized. The experiments were carried out in several simulated soil solutions corresponding to
several soil samples collected from various regions along a buried pipeline with overhead parallel high voltage power
transmission line. The results indicated that AC corrosion depends strongly on the composition of the soil.
A. Shokuhfar, S. Ahmadi, H. Arabi, S. Nouri,
Volume 6, Issue 3 (9-2009)
Abstract
Abstract: Guinier-Preston (GP) zone formation and precipitation behavior of T1 (Al2CuLi) phase during the ageingof an Al-Cu-Li-Zr alloy was studied by differential scanning calorimetry (DSC) technique and electrical resistancemeasurement of the samples. Results show that endothermic effects in the thermograms of the alloy between 180°Cand 240°C can be related to the enthalpy of GPzones dissolution. Formation of GPzones in the structure increasedhardness, tensile strength and electrical resistance of the Al-Cu-Li-Zr alloy. Furthermore, precipitation of T1 phaseoccurred in temperature range of 250ºC to 300ºC whereas its dissolution occurred within the temperature of 450-530ºC. Activation energies for precipitation and dissolution of T1 phase which were determined for the first time inthis research, were 122.1(kJ/mol) and 130.3(kJ/mol) respectively. Results of electrical resistance measurementsshowed that an increase in the aging time resulted in the reduction of electrical resistance of the aged samples.
Mr. Hossein Minouei, Dr. Mohammadhossein Fathi, Dr. Mahmood Meratian, Mr. Hossein Ghazvinizadeh,
Volume 9, Issue 3 (9-2012)
Abstract
ASTM F-75 Cobalt-base alloy castings are widely used for manufacturing orthopedic implants. This alloy needs both homogenization and solutionizing heat treatment after casting, as well as bioactivation of the surface to increase the ability of tissue bonding. In this study, ASTM F-75 Cobalt-base substrate was heat treated at 1220°C for 1 hour in contact with Hydroxyapatite-Bioglass powder in order to solutionize and homogenize the microstructure and promote surface bioactivation. For bioactivity evaluation, heat treated specimens were immersed in Simulated Body Fluid (SBF). Surface of specimens before and after the immersion was analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX) and X-Ray Diffraction (XRD). Results showed an appropriate microstructure with bioactive layer on the surface of specimens after heat treatment. In vitro result and formation of bone-like apatite layer on specimens indicated that heat treated samples were potentially suitable for bone replacement and tissue regeneration under highly loaded conditions.
Dr Mohammad Reza Sarmasti Emami,
Volume 9, Issue 3 (9-2012)
Abstract
This paper presents an experimental and theoretical investigation of the causes of corrosion of stack in a cement plant. In this paper, information related to metallic stack failures are given in the form of a case study in Neka Cement Plant, Mazandaran, Iran. Heavy corrosion attacks were observed on the samples of stack. The failure can be caused by one or more modes such as overheating, stress corrosion cracking (SCC), hydrogen embrittlement, creep, flame impingement, sulfide attack, weld attack, dew point corrosion, etc. Theoretical calculations and experimental observations revealed that, the corrosion had taken place due to the condensation of acidic flue gases in the interior of stack. Also, the chemical analysis of the corrosion deposits and condensates confirmed the presence of highly acidic environment consisting of mostly sulfate ions.
N Parvin, R Derakhshandeh Haghighi, M Naeimi, R Parastar Namin, M. M. Hadavi,
Volume 11, Issue 4 (12-2014)
Abstract
In this research, infiltration behavior of W-Ag composite compacts with Nickel and Cobalt as additives has been investigated. Nickel and Cobalt were added to Tungsten powder by two distinct methods: mixing elementally and reduction of salt solution. The coated Tungsten powders were compacted under controlled pressures to make porous skeleton with 32-37 vol. % porosity. Infiltration process was carried out at 1100 ̊C under a reducing atmosphere for 1h. The effect of additives on infiltration of Ag and density were evaluated by SEM and Archimedes methods. Properties of the specimens were compared following two distinct processes namely: I) sintering simultaneously with infiltration process and II) sintering prior to infiltration (pre-sintering process). It was found that specimens which were pre-sintered and then infiltrated with molten silver represent higher hardness and finer microstructure than the specimens infiltrated simultaneously with sintering.
Z. Valefi, M. Saremi,
Volume 14, Issue 2 (6-2017)
Abstract
In this paper the effect of plasma spray parameters, atomizing gas and substrate preheat temperature on microstructure and phase composition of YSZ coatings produced by SPPS process have been investigated. The experimental results showed that increasing the power of plasma, using hydrogen as the precursor atomizing gas and increasing substrate preheat temperature decrease the amount of non-pyrolyzed precursor in the coatings. At low plasma power most of the deposited precursor is in non-pyrolyzed state, and consequently the applied coatings are defective. The increase in substrate temperature beyond 800oC either by preheating or heat transfer from plasma torch to the substrate, prevent the coating formation. In SPPS coating formation, up to a special spray distance the optical microscopy image of the coatings showed a snowy like appearance. XRD analysis showed that in this situation the amount of un-pyrolyzed precursor is low. Beyond this spray distance, spherical particles, are obtained and XRD analysis showed that most of the precursor is in un-pyrolyzed state.
M. Fallah Tafti, M. Sedighi, R. Hashemi,
Volume 15, Issue 4 (12-2018)
Abstract
In this study, the microstructural variations, mechanical properties and forming limit diagrams (FLD) of Al 2024 aluminum alloy sheet with the thickness of 0.81mm are investigated during natural ageing (T4) treatment. The most formability in Al 2024 can be achieved just after solution treatment, and it is better to perform the forming process, on this aluminum alloy sheet, in this condition. However, in industrial applications, there is usually a postponement for some hours after solution treatment to begin the forming process that it means the forming process should be done at the natural ageing condition. This condition decreases the formability of Al 2024 sheets. To monitor the properties variations in natural ageing condition, FLDs are determined after specific times (e.g., 0.5, 1.5, 4 and 24 hours). The variations in micro-hardness, yield strength, ultimate tensile strength and elongation at break are observed with changing the ageing time. The scanning electron microscope (SEM) investigations illustrated that density and size of precipitates are changed with ageing time. Moreover, the Nakazima test is utilized to study the forming limits considering the natural ageing condition. Results show by increasing the ageing time, up to 4hr, the majority of properties variations could be seen, and from 4hr to 24hr, the variations are changed slower.
Morteza Hadi, Omid Bayat, Hadi Karimi, Mohsen Sadeghi, Taghi Isfahani,
Volume 19, Issue 1 (3-2022)
Abstract
In this research, the effect of initial microstructure and solution treatment on rollability and crystallographic texture of a Cu-Mn-Ni-Sn alloy has been investigated. The initial tests indicated that the rolling of the alloy at different temperature conditions is not possible due to formation of second phases. Herein to eliminate the segregated phases, according to DTA analysis, proper temperature for solution treatment was selected as 750°C applied at different periods of time. The obtained results showed that after 15-hour solution treatment, the complete elimination of Sn, Mn, Ni, and Fe-rich phases can be achieved. Also, the peaks of XRD shifted to the higher angles indicating that the alloying elements are dissolved. Meanwhile, the intensity of the texture reduced and the dominant texture changed from Goss and Brass-texture to Copper-texture. Accordingly, the amount of maximum total reduction at the rolling process increased from 16.37 to 109.46 after solution treatment.
Hamed Nadimi, Hossein Sarpoolaky, Mansour Soltanieh,
Volume 20, Issue 4 (12-2023)
Abstract
In the present investigation, an attempt was made to evaluate the dissolution behavior of Ti in molten KCl-LiCl. The X-ray diffraction (XRD) pattern of heated Ti plate at 800 oC for 4 h without carbon black in molten salt revealed that TiCl3 formation was feasible. For more assurance, Ti plate was heated at 950 oC for 4 h in the presence of carbon black to identify synthesized TiC. Transmission electron microscope (TEM) and scanning electron microscope (SEM) images from precursors and the final product showed that nano-crystalline TiC formation from coarse Ti particles was almost impossible without Ti dissolution. Thermodynamics calculations using Factsage software proved that it was possible to form various TiClx compounds. The TiC formation mechanism can be discussed in two possible ways: a reaction between Ti ion and carbon black for synthesizing TiC (direct) and a reaction between TiCl4 and carbon black led to indirect TiC synthesis. Elemental mapping using energy dispersive X-ray spectroscope (EDS) indicated that up to 815 oC, chlorine existed in the map.
