Investigation of hydrothermal synthesis of wollastonite using silica and nano silica at different pressuresV

Hamid Reza Rezaie,Arash Yazdani,Hossein Ghassai 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.3

In this research a hydrothermal method was applied to synthesis of wollastonite. Silica, nano silica and calcium carbonate were used as raw materials. Different slurries were prepared with SiO2/CaO molar ratios of 0.54, 0.8, 1 and a solid content of 50 wt%. Then the slurries were hydrothermally treated in an autoclave for 2 h at 200 oC at pressures of 3, 5 and 7 atm. In the next step, the samples were dried at 150 oC for 8 h and then were calcined at 1000 oC for 5 h. The microstructure and phase analyses were investigated using SEM and XRD. The results showed that by using both silica and nano silica, with increasing pressure, the amount of wollastonite increased. At all pressures using silica, slurry with 50 wt% of solid content, SiO2/CaO molar ratio of 0.8 gave the optimum results while by using nano silica the optimum SiO2/CaO molar ratio was 1.

Solution of combined economic and emission dispatch problem using a novel chaotic improved harmony search algorithm

Hamid Rezaie,M.H. Kazemi-Rahbar,Behrooz Vahidi,Hasan Rastegar 한국CDE학회 2019 Journal of computational design and engineering Vol.6 No.3

This paper presents a new optimization technique developed based on harmony search algorithm (HSA), called chaotic improved harmony search algorithm (CIHSA). In the proposed algorithm, the original HSA is improved using several innovative modifications in the optimization procedure such as using chaotic patterns instead of uniform distribution to generate random numbers, dynamically tuning the algorithm parameters, and employing virtual harmony memories. Also, a novel type of local optimization is intro-duced and employed in the algorithm procedure. Applying these modifications to HSA has resulted in enhancing the robustness, accuracy and search efficiency of the algorithm, and significantly reducing the iterations number required to achieve the optimal solution. To validate the effectiveness of CIHSA, it is used to solve the combined economic emission dispatch (CEED) problem, which practically is a com-plex high-dimensional non-convex optimization task with several equality and inequality constraints. Six test systems having 6, 10, 13, 14, 40, and 140 generators are investigated in this study, and the valve-point loading effects, ramp rate limits and power transmission losses are also taken into account. The results obtained by CIHSA are compared with the results reported in a large number of other research works. Furthermore, the statistical data regarding the CIHSA performance in all test systems is presented. The numerical and statistical results confirm the high quality of the solutions found by CIHSA and its superiority compared to other existing techniques employed in solving CEED problems.

Effect of soil in controlling the seismic response of three-dimensional PBPD high-rise concrete structures

Hamid Mortezaie,Freydoon Rezaie 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.2

In the last decades, valuable results have been reported regarding conventional passive, active, semi-active, and hybrid structural control systems on two-dimensional and a few three-dimensional shear buildings. In this research, using a three-dimensional finite element model of high-rise concrete structures, designed by performance based plastic design method, it was attempted to construct a relatively close to reality model of concrete structures equipped with Tuned Mass Damper (TMD) by considering the effect of soil-structure interaction (SSI), torsion effect, hysteresis behavior and cracking effect of concrete. In contrast to previous studies which have focused mainly on linearly designed structures, in this study, using performance-based plastic design (PBPD) design approach, nonlinear behavior of the structures was considered from the beginning of the design stage. Inelastic time history analysis on a detailed model of twenty-story concrete structure was performed under a far-field ground motion record set. The seismic responses of the structure by considering SSI effect are studied by eight main objective functions that are related to the performance of the structure, containing: lateral displacement, acceleration, inter-story drift, plastic energy dissipation, shear force, number of plastic hinges, local plastic energy and rotation of plastic hinges. The tuning problem of TMD based on tuned mass spectra is set by considering five of the eight previously described functions. Results reveal that the structural damage distribution range is retracted and inter-story drift distribution in height of the structure is more uniform. It is strongly suggested to consider the effect of SSI in structural design and analysis.

Effect of soil in controlling the seismic response of three-dimensional PBPD high-rise concrete structures

Mortezaie, Hamid,Rezaie, Freydoon Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.2

In the last decades, valuable results have been reported regarding conventional passive, active, semi-active, and hybrid structural control systems on two-dimensional and a few three-dimensional shear buildings. In this research, using a three-dimensional finite element model of high-rise concrete structures, designed by performance based plastic design method, it was attempted to construct a relatively close to reality model of concrete structures equipped with Tuned Mass Damper (TMD) by considering the effect of soil-structure interaction (SSI), torsion effect, hysteresis behavior and cracking effect of concrete. In contrast to previous studies which have focused mainly on linearly designed structures, in this study, using performance-based plastic design (PBPD) design approach, nonlinear behavior of the structures was considered from the beginning of the design stage. Inelastic time history analysis on a detailed model of twenty-story concrete structure was performed under a far-field ground motion record set. The seismic responses of the structure by considering SSI effect are studied by eight main objective functions that are related to the performance of the structure, containing: lateral displacement, acceleration, inter-story drift, plastic energy dissipation, shear force, number of plastic hinges, local plastic energy and rotation of plastic hinges. The tuning problem of TMD based on tuned mass spectra is set by considering five of the eight previously described functions. Results reveal that the structural damage distribution range is retracted and inter-story drift distribution in height of the structure is more uniform. It is strongly suggested to consider the effect of SSI in structural design and analysis.

Preparation and mechanical properties of alumina/spinel/ metal composite with three different sintering methods

Jafar Baseri,Rahim Naghizadeh,Hamid Reza Rezaie 한양대학교 세라믹연구소 2017 Journal of Ceramic Processing Research Vol.18 No.1

Alumina-spinel(NiAl2O4, CoAl2O4 solid solution)-metal(nickel, cobalt solid solution) composites were fabricated by partialreduction of spinel in carbon-bed and sintered with three different processes namely, pressureless, hot pressing, and sparkplasma sintering (SPS). The microstructural features and mechanical properties of composites were investigated. Thepressureless samples, SPS samples, and hot pressed samples reached > 91%, > 97% and > 98% theoretical density,respectively. The flexural strength of SPS, hot pressed, and pressureless samples were about 415 MPa, 367 MPa, and 247 MPa,respectively. Vickers Microhardness of SPS, hot pressed, and pressureless sintering were about 15.3, 14.5, and 10.98 GPa,respectively. The fracture toughness of SPS and hot pressed samples did not have a significant difference, and they were about7.2 and 7.8 MPa.m1/2, repectively

Synthesis of dehydrated magnesium borate powders and the effect on the properties of MgO-C refractories

Mahdi Heidari Bagherabadi,Rahim Naghizadeh,Hamid Reza Rezaie,Mohsen Fallah Vostakola 한양대학교 세라믹연구소 2018 Journal of Ceramic Processing Research Vol.19 No.3

For the synthesis of magnesium borate powder, magnesium carbonate and boric acid powders were mixed in ethanol and theninvestigated by differential thermal analysis (DTA) and thermogravimetry (TG). X-ray diffraction (XRD) results of thesamples showed the formation of Mg2B2O5 phase at 500 oC and Mg3B2O6 at 650 oC. The synthesized powder used as anantioxidant additive in magnesia-graphite bodies containing 20% graphite. After curing at 200 oC and firing at 1200 oC and1400 oC for 2 hrs in a coke bed environment, its physical and mechanical properties and also microstructural features wereinvestigated. The results showed that after curing at 250 oC, the addition of magnesium borate led to an increase in coldcrushing strength at about 20%. Comparing the samples with additives and without any additives at 1200 and 1400 oC showedthat the cold crushing strengths were improved about 45%, 35%, respectively. In addition, the results clarified that magnesiumborate (Mg3B2O6) phase led to improve oxidation resistance.

Synthesis and comparison of MgAl2O4-Ti [C, N] composites using aluminothermic-carbothermal reduction and molten salts routes

Elaheh Khosh Omid,Rahim Naghizadeh,Hamid Reza Rezaie 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.4

MgAl2O4-Ti (C, N) composites were synthesized through aluminothermic-carbothermal reduction and molten salts synthesis (MSS) routes in coke bed conditions. The phases were characterized using X-ray diffraction (XRD) and microstructures of composites were investigated by scanning electron microscopy (SEM). The results showed that the synthesis temperature of MgAl2O4-Ti (C, N) was decreased about 300 o C in MSS method in comparison with aluminothermic-carbothermal reduction. The KCl and NaCl salts proved better transportation path for reactant species and accelerate composite formation and also establish the microstructure with homogenous and fine grains.

Processing and properties of Ni dispersed zirconia toughened alumina

Mayssam Hussein Nabbouh,Rahim Naghizadeh,Farhad Golestani-Fard,Hamid Reza Rezaie 한양대학교 세라믹연구소 2017 Journal of Ceramic Processing Research Vol.18 No.9

The combination of phase transformation of zirconia and plastic deformation of Ni metal has shown a significant improvement in toughness caused by the synergistic toughening. In the present study, the reduction process within a carbon bed, the effectof Ni content on densification, microstructure and mechanical properties of ZTA/Ni composites was investigated. Powder mixtures of Al2O3, 3YSZ, and nickel nitrate as a source of Ni metal were prepared by precipitated Ni on ceramic powders to obtained ZTA/Ni composites. The composites were pressureless sintered at 1600 o C for 3 hrs within a carbon powder bed. The results showed that the addition of 5 vol.% Ni results in the highest relative density of 93% and the maximum fracture strength and toughness values of 348 MPa and 3.32 MPa.m½, respectively.

The effect of talc on the reaction sintering, microstructure and physical properties of Al2TiO5 based ceramics

Golsa Naderi,Ali ShokuhFar,Rahim Naghizadeh,S. Atashgar,Hamid Reza Rezaie 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.1

Tialite (Al2TiO5) is a ceramic material of very low thermal expansion coefficient, excellent thermal shock resistance, high refractoriness and good corrosion resistance. However, industrial applications of this material are hindered by two major limitations: decomposition to its parent oxides, alumina and rutile between 800 and 1280 oC and its low thermal mechanical properties. In the present study addition of talc with a good stabilizing effect has been studied on aluminum-titanate (tialite)- based ceramics. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the effect of talc on phase evolutions, sintering, and the microstructure of aluminum-titanate, and also density measurements were performed after sintering. The results showed that the presence of talc reduces the unreacted alumina and rutile significantly. The formation of Mg0.3Al1.4Ti1.3O5 and other solid solutions of MgO and aluminum-titanate were observed. Tialite (Al2TiO5) is a ceramic material of very low thermal expansion coefficient, excellent thermal shock resistance, high refractoriness and good corrosion resistance. However, industrial applications of this material are hindered by two major limitations: decomposition to its parent oxides, alumina and rutile between 800 and 1280 oC and its low thermal mechanical properties. In the present study addition of talc with a good stabilizing effect has been studied on aluminum-titanate (tialite)- based ceramics. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the effect of talc on phase evolutions, sintering, and the microstructure of aluminum-titanate, and also density measurements were performed after sintering. The results showed that the presence of talc reduces the unreacted alumina and rutile significantly. The formation of Mg0.3Al1.4Ti1.3O5 and other solid solutions of MgO and aluminum-titanate were observed.