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Effect of cobalt replacement by nickel on functionally graded cemented carbonitrides
, Article International Journal of Refractory Metals and Hard Materials ; Volume 30, Issue 1 , January , 2012 , Pages 42-47 ; 02634368 (ISSN) ; Abachi, P ; Pourazarang, K ; Sharif University of Technology
2012
Abstract
Functionally graded cemented carbonitrides (FGCCs) are applied in cutting tools industry. Indexable inserts made from mentioned alloys have superior cutting performance and tool life thanks the formation of a surface modified layer with enhanced properties as well as crater wear resistance. Cemented carbonitrides are made of hard carbide/nitride/carbonitride particles that have been embedded in a metallic binder. Excellent wetting ability of tungsten carbide with cobalt has made this metal the first choice as binder. However, cobalt has high cost and environmental pollution impacts. Substitution of cobalt with other metals has always been figured out. Some other metals that have been used as...
Semantic Based Web Service Classification
, M.Sc. Thesis Sharif University of Technology ; Sadighi Moshkenani, Mohsen (Supervisor)
Abstract
Web services are some kind of software applications which are available on the Web. Growing the popularity of Web services, led to increasing number of providers and as a result a great deal of Web services. This huge number of services made the searching and discovery tasks hard and effort-full jobs. In order to have a better discovery it is better to first classify Web services into some categories and then search in the relevant class. Although this classification can be done based on matching key words through the service registration information, such syntax-level service facilities can’t achieve the satisfaction results both in the precision and the recall sides. Human experience shows...
On the formation of intermetallics during the furnace brazing of pure titanium to 304 stainless steel using Ag (30-50%)-Cu filler metals
, Article Materials and Manufacturing Processes ; Volume 25, Issue 11 , 2010 , Pages 1333-1340 ; 10426914 (ISSN) ; Abachi, P ; Dehghani, K ; Pourazarang, K ; Sharif University of Technology
2010
Abstract
In the present work, the effect of brazing pa rameters on the properties of the brazed joint of pure titanium and 304 stainless steel (304SS) was investigated. Three different Ag-Cu filler metals were used, while the temperature and time of brazing were in the range of 800-950°C and 5-45 minutes, respectively. The microstructural observations show that, depending on the brazing conditions, different intermetallic phases such as CuTi2, CuTi, Cu3Ti4, and FeTi were formed at the phases interface. Based on the microstructural observations, a model was developed to characterize the formation of phases at the interfaces and brazed joint. The results show that, while some phases may form during the...
production of Nickel- Aluminide Nanocomposite Reinforced with Al2O3 Nanoparticles Via Mechanical Alloying Route and Field Activated Sintering Technique
, M.Sc. Thesis Sharif University of Technology ; Abachi, Parvin (Supervisor) ; Pourazarang, Kazem (Supervisor)
Abstract
Nickel aluminides are intermetalics with complex structures that have high metlting points. However, brittlement at room temperature and low high_temperature strength (above 700 ̊C) can be mentioned as their short comings. Nowadays, many efforts have been proceeded to produce theirs composites, so that one can benefit from ceramics and intermettalics properties simultaneously. In this project, the main was aim to produce NiAl matrix nanocomposite reinforced with Alumina Al2O3. The composite is processed using milling and mechanical alloying. This is a good way to produce intermetallics and their composites with high melting points without any need to supply high temperature during...
Preparation of Cu-TiC Nanocomposite and Investigation of Microstructure, physical and Mechanical Properties
, M.Sc. Thesis Sharif University of Technology ; Pourazarang, Kazem (Supervisor) ; Abachi, Parvin (Co-Advisor)
Abstract
In this study, Cu-TiC nanocomposites were produced by high energy ball milling of elemental powders and in situ formation of TiC in the copper base. Cu and 5,10,20 and 40 wt% Ti powder blend were milled for 60 h, then graphite powders were added and milling was continued for 10 h again and Finally Cu-TiC composite powders with 10.68, 20.16, 36.24 and 60.25 vol% of reinforcements (6.18, 12.2, 23.82 and 45.47 wt%) were produced. The effect of time on the solution of titanium in the copper was studied by X-Ray diffraction analysis (XRD). crystallite size and lattice strain of copper were determined 12nm and 1.04% subsequently for Cu-40wt%TiC after 60 h milling. to ensure the formation of...
Preparation of Cu-MoSi2 Nanocomposite by Mechanical Alloying and Investigation of Properties
, M.Sc. Thesis Sharif University of Technology ; Pourazarang, Kazem (Supervisor) ; Abachi, Parvin (Supervisor)
Abstract
In this study, to synthesize molybdenum disilicide nano powder, mixed powder of Mo and Si were ball milled for 15, 30, 45 and 55 hours. By the results of the analyses, milled powders for time intervals of 55 hours were heat treated to release the stresses. This process was carried out in an argon vacuum tube furnace at 1000˚C for 1 hour. XRD analysis was carried for sample. Finally, MoSi2 powder with 86.62 nm crystallite size was used as reinforcement. Cu-MoSi2 composite powder with 2, 3, 5wt% were produced. Cu-MoSi2 with 2wt% reinforcement was milled for 60 hours. Powder composite was compacted by Spark Plasma Sintering . Microstructure of composite was investigated by scanning electron...
Production of Zirconium based Amorphous Alloy by Mechanical Alloying and Sintering Al-based Composite with Amorphous Particles
, M.Sc. Thesis Sharif University of Technology ; Pourazarang, Kazem (Supervisor) ; Abachi, Parvin (Supervisor)
Abstract
Production of copper-zirconium amorphous alloys by mechanical alloying and the process of changing crystal structure to amorphous, was examined. The amount of progress of amorphization has been checked by x-ray analysis after different hours of milling. By increasing the percentage of zirconium in this type of alloy, the process of amorphization has been improved. But There is a limiting factor which is due to the tendency of zirconium to produce oxide and nitride phase. Also, the effect of excessive elements on crystal structure changing has been checked. Hence, adding elements like nickel or aluminum has a different effect on the process of amorphization. adding aluminum to the system...
Fabrication of insitu Cu/TiO2p Nanocomposite by Internal oxidation with Mechanical Alloying and Evaluation its Physical and Mechanical Properties
, M.Sc. Thesis Sharif University of Technology ; Pourazarang, Kazem (Supervisor) ; Abachi, Parvin (Supervisor)
Abstract
Basically, it is required that the materials used as electrical contacts should have good thermal and electrical conductivity and certain strength. The copper base composites with fine TiO2 particles as reinforcement have almost identical electrical and thermal conductivity with copper; in addition, they have the advantage over pure copper in high strength owing to the dispersion of the fine TiO2 particles, which improve copper matrix strength through impeding dislocation movement. In this present work, at the initial stage, Cu and Ti powders were mechanically alloyed for 60h under Argon atmosphere, and then added Cu2O powders as oxidant. The specimens, containing different amounts of TiO2,...
The Fabrication of Copper base Chromium Oxide Reinforced Nanocomposite and Investigation of its Mechanical and Physical Properties
, M.Sc. Thesis Sharif University of Technology ; Pourazarang, Kazem (Supervisor) ; Abachi, Parvin (Supervisor)
Abstract
It is well known that Cu/Al2O3 nanocomposites have high potential for use in structural, electrical applications which enhanced mechanical characteristics are required. In the present work, in order to improve the in-situ oxidation kinetic of solute element, chromium was used instead of aluminum. At the initial stage, elemental Cu and Cr powders were mechanically alloyed for 60h under argon atmosphere. It was followed by mechanically milling of Cu-Cr pre-alloyed and Cu2O powders. The nanocomposite specimens, containing different amounts of Cr2O3, depending on the Cr content in the range of 1-3 wt. %, were produced by in-situ oxidation of Cu-Cr pre-alloyed powders. To prevent oxidation of...
Preparation of in-situ Cu/NbC nanocomposite and its functionally graded behavior for electrical contact applications
, Article Transactions of Nonferrous Metals Society of China (English Edition) ; Volume 25, Issue 3 , 2015 , Pages 863-872 ; 10036326 (ISSN) ; Abachi, P ; Pourazarang, K ; Mohammadi Rahvard, M ; Sharif University of Technology
Nonferrous Metals Society of China
2015
Abstract
Abstract Cu-15%NbC (volume fraction) powder was synthesized using the starting powders of Cu, Nb and graphite in a high energy vibratory disc mill for 7 h of milling under argon atmosphere. A composite sample and a Cu/NbC functionally graded material (FGM) sample were produced by using the two-step press and sintering at 900 °C for 1 h under vacuum. The microstructure and physical and mechanical properties of the specimens were investigated. The field emission scanning electron microscopy, energy dispersive X-ray and X-ray diffraction analysis confirmed the synthesis of the nanostructure matrix of 18-27 nm with the nanoparticles reinforcement of 42 nm after sintering, verifying the thermal...
The Effect of Some Production Parameters on Microstructure, Physical and Mechanical Properties of Powder Metallurgically Produced (90W-7Ni-3Fe) Heavy Alloy
, M.Sc. Thesis Sharif University of Technology ; PourAzarang, Kazem (Supervisor) ; Abachi, Parvin (Supervisor)
Abstract
In applications requiring high density and good mechanical properties, tungsten heavy alloys are of interest [1]. Due to lack of intermetallic phase in microstructure of 90W-7Ni-3Fe alloy, it is more attractive to use. At present work, the powder metallurgically produced specimens were cold swaged. At this work, during the production and swaging, some parameters were changed. Powders of tungsten, nickel and iron were milled for an hour with the speed of 50 rpm in Retsch Planetry/PM 400 MA ball mill. At the first route, elemental powders mixture after 1 minute were reached to 30MPa, after that were heated at rate of 50°C/min to 1500°C in vacuum (hot press or HP). At the second route, powders...
“Production of Micro and Nanocomposites of Fe3Al/ZrO2 Via Mechanical Alloying and Surveying of Mechanical Properties”
, M.Sc. Thesis Sharif University of Technology ; Pourazarang, Kazem (Supervisor) ; Salahi, Esmail (Supervisor)
Abstract
In this investigation, nanostructure Fe3Al was produced by mechanical milling initially. Pure iron and aluminum powders were milled with suitable ratio 86Fe-14Al by weight. Milling was done up to 120 h times and with BPR 10 and BPR 20. Morphological changes, powder density and size, phase and structural changes, grain size and lattice strain were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and laser particle size analyzer (LPSA). 40 h mechanical alloying with BPR 20 led to the corresponding intermetallic compound, Fe3Al with a nanocrystalline structure. Therefore Fe3Al/ZrO2 micro and nanocomposite powders were synthesized with manufactured by milling of...