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    The Corrosion Behavior of Zinc and SiO2 Composite Coating

    , M.Sc. Thesis Sharif University of Technology Salehi, Farshad (Author) ; Ghorbani, Mohammad (Supervisor)
    Main aim of this work was to obtain the harder zinc coating and increasing the anti corrosive properties by mean of adding SiO2 particles by electrophoretic method.
    The coating was applied on the substrate surface by mean of electro co-deposition technique in three different electrolytes ethanol, methanol and water. The morphology of the coating in each electrolyte studied by scanning electron microscope (SEM).For the Zn/SiO2 coatings achieved in ethanol solvent the polarization and EIS tests was took place and found that for the Zn/SiO2 coating contain less than 10% SiO2 the corrosion rate decreased but for the coatings contains more than 10% SiO2 the paradox occurred because of the... 

    Production of Al-TiO2 composite layer by friction stirs processing

    , M.Sc. Thesis Sharif University of Technology Nami, Hamid (Author) ; Kokabi, Amir Hossein (Supervisor) ; Maddah Hosseini (Co-Advisor)
    In this study, Al-TiO2 composites layer were produced on Al 1100 substrate using friction stir processing technique. The variation of process parameters such as tool rotational and substrate advancing speed as well as number of FSP passes were adjusted to achieve quite uniform dispersion of Nano-particles in the Al matrix of the fabricated surface layer. Microstructural observations were carried out using optical and scanning electron microscopes. By increasing the FSP passes, uniform distribution of TiO2 particles in the matrix improved. Surface composition layer exhibited a micro-hardness value of 49 HV which was around twice of the as-received substrate. In addition wear resistance of... 

    Effect of Nano Alumina Particles Addition in Electrolyte by Micro arc Oxidation Process on Titanium Substrate

    , M.Sc. Thesis Sharif University of Technology Sarbishei, Sahand (Author) ; Faghihi-Sani, Mohammad Ali (Supervisor) ; Mohammadi, Mohammad Reza (Supervisor)
    Titanium and its alloys have wide applications in industry and recently researches have been expanded in this area. The main reasons are unique features of titanium such as biological behavior, corrosion resistance and high strength to weight ratio. The fundamental problem of titanium is low wear resistance that leads to be worn in industrial applications. For more efficiency of titanium, extensive efforts have been made for solving this problem, one of the best solutions is coating.Micro Arc Oxidation (MAO) is a novel method to create ceramic coatings on metals to improve wear and corrosion resistance. In this research nano alumina particles were added to electrolyte to create... 

    Coating of MgO Thin Film on Porous NiTi Supper Elastic Alloy by MAO

    , M.Sc. Thesis Sharif University of Technology Falaki, Sajjad (Author) ; Sadrnezhad, Khatiboleslam (Supervisor)
    The novel Micro Arc Oxidation technique (MAO) is gaining increased attention for depositing thick, dense, corrosion resistant and hard ceramic coating on metals. In this research, the effects of parameters including electrolyte composition and coating time on properties of MAO coatings formed on NiTi were investigated. The surface morphology, thickness and phase composition of coatings were investigated using scanning electron microscope and X-ray diffraction. Corrosion behavior of the coatings was examined by potentiodynamic polarization. Also wear resistance was examined by pin on disk test. It was found that MAO coatings improve corrosion resistance of NiTi. All of these applied... 

    Test methodology and wear characteristics of austenitic stainless steel aisi type 316 at cryogenic environment

    , Article Lecture Notes in Engineering and Computer Science ; Vol. 2 , 2-4 July , 2014 , pp. 1214-1217 ; ISSN: 20780958 ; ISBN: 9789881925350 Farrahi, G. H ; Kazerani, V ; Ghorashi, M. S ; Sharif University of Technology
    Components in cryogenic milieu with relative motion, like seals and pumps cannot be lubricated by using oils or other lubricants. Therefore materials wear in cryogenic condition is a great concern. To earn valid data about the wear properties of common and super useful material in cryogenic tribosystems, reconstruction wear test apparatus at cryogenic temperature is needed. Investigations on metal-metal couple show that austenitic stainless steels have favorable and auspicious sliding properties at cryogenic temperature. This research provides the wear parameters of austenitic stainless steel AISI type 316 in cryogenic environment. For this purpose two sets of test environment are prepared,... 

    Effect of superheat and solidified layer on achieving good metallic bond between A390/A356 alloys fabricated by cast-decant-cast process

    , Article Transactions of Nonferrous Metals Society of China (English Edition) ; Vol. 24, issue. 3 , March , 2014 , p. 665-672 Rahvard, M. M ; Tamizifar, M ; Boutorabi, M. A ; Shiri, S. G ; Sharif University of Technology
    The cast-decant-cast is a new method for the preparation of the functionally graded components that has been developed in recent years. The functionally graded cylindrical shape component with a radial gradient, e.g. the first alloy (A390) with high wear resistance on the surface of the piece and toughness and the second alloy (A356) of low machining costs in the core of the piece can be produced via this melt process. The effect of the second alloy superheat at temperatures of 750, 820 and 860 °C as well as the effect of the first alloy solidified layer at 25, 35 and 45 s decanting time on achieving the perfect interface between the two alloys was investigated. The characterization of the... 

    Effect of Heat Treatment on Wear Behavior of High Chromium White Cast Iron

    , M.Sc. Thesis Sharif University of Technology Aalinejad, Davood (Author) ; Varahram, Nasser (Supervisor)
    It is well known that all crusher tools, which are exposed to wear, must be resistant to both wear and dynamic tensions that can result in catastrophic failures. Tools exposed to heavy tensions should have two opposing properties, which are wear resistivity and toughness. To achieve the best wear resistivity in crusher tools, it is better to have martensitic matrix. During the cooling process, transformation of austenite to perlite occurs and presence of perlite adjacent to carbides extremely reduces the wear resistivity of the work piece. Although because of high solvability of carbon into austenite, stability of austenite in room temperature is possible. Under wear circumstances and... 

    Nitinol spinal vertebrae: A favorable new substitute

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 32, Issue 6 , 2019 , Pages 842-851 ; 1728144X (ISSN) Sadrnezhaad, S. K ; Parsafar, M ; Rashtiani, Y ; Jadidi, M ; Sharif University of Technology
    Materials and Energy Research Center  2019
    Scoliosis, kyphosis, and bone fracture are health problems, especially of the elderly throughout the world. The vertebra protects the spinal cord. Any impairment to the vertebra can lead to pain and nervousness. NiTi alloy (Nitinol) helps to resolve the problem by fulfilling such requirements as for strength, durability, resistance to wear, and shockwave damping which is due to the shape memory effect. Nitinol medical applications have so far been restricted to surgical devices and orthopaedics. Little has been said about Nitinol use for medication of the spinal vertebra disorder. This article appraises the potential features of Nitinol for vertebral implantation and therapeutic prescription... 

    Effect of deep cryogenic treatment on wear resistance and tool life of M2 HSS drill

    , Article Journal of Materials Processing Technology ; Volume 206, Issue 1-3 , 12 September , 2008 , Pages 467-472 ; 09240136 (ISSN) Firouzdor, V ; Nejati, E ; Khomamizadeh, F ; Sharif University of Technology
    The influence of deep cryogenic treatment on wear resistance and tool life of M2 HSS drills in high-speed dry drilling configuration of carbon steels was studied. The experimental results indicated 77 and 126% improvement in cryogenic-treated and cryogenic- and temper-treated drill lives, respectively. The results of wear rate test were in agreement with drill life test. Chemical composition of chips were also reported to show the onset of seizure in drilling test and the consequence of seizure in promoting dissolution wear by diffusion mechanism. Wear resistance improvement was mainly attributed to the resistance of cryogenically treated drills against diffusion wear mechanism, due to the... 

    Effects of tungsten on erosion-corrosion behavior of high chromium white cast iron

    , Article Materials Science and Engineering A ; Volume 454-455 , 2007 , Pages 623-628 ; 09215093 (ISSN) Mousavi Anijdan, S. H ; Bahrami, A ; Varahram, N ; Davami, P ; Sharif University of Technology
    In this study, effects of tungsten on wear resistance of high chromium white cast iron with and without tungsten in erosion-corrosion condition have been investigated. At the same time, the comparison between wear resistance of this grade of cast iron and low alloy steels with various contents of Cr which are used in industrial condition (in Sarcheshme Company, the greatest copper production company in the Middle East and with more than 4000 years historical cupper production background) was studied, while, copper concentrates have used for erosion particles. Results show that, because of higher hardness of matrix due to the tungsten, the wear resistance of high chromium cast iron increases.... 

    Wear and friction characteristics of electrodeposited graphite-bronze composite coatings

    , Article Surface and Coatings Technology ; Volume 190, Issue 1 , 2005 , Pages 32-38 ; 02578972 (ISSN) Ghorbani, M ; Mazaheri, M ; Afshar, A ; Sharif University of Technology
    The wear and friction properties of G-Cu (Sn) composite coatings containing different amounts of graphite particles were examined. The presence of graphite particles improved antifriction properties of composite coatings. The effects of graphite percent in composite coating, tin content of matrix, load, speed and distance on the coefficient of friction and wear resistance of bronze-graphite composite coatings were studied. The results of the present studies revealed that hardness, wear resistance, coefficient of friction are dependent on volume percentage of graphite in composite coating. It was shown that the composite coating containing approximately 5.4 (vol.%) graphite and matrix with... 

    Wear Behavior of Cast Rods Manufactured for Hard Surfacing Iron Based Alloy

    , M.Sc. Thesis Sharif University of Technology Momeni, Hadi (Author) ; Kokabi, Amir Hossein (Supervisor) ; Varahram, Naser (Supervisor)
    Wear of parts during service is one of the main factors of damage to the industrial parts. From among various kinds of wear, abrasive wear has the most role in damage of industrial parts. Hard surfacing is a useful and cost effective method for improving the surface properties of parts. This method is made through coherent layer sediment from the alloys resistant to abrasion, oxidation and wear by welding or spray. Determining the appropriate alloy for hard surfacing operations need knowing of working conditions of the part and the type of occurred abrasion. Ordinarily, the alloys which are prepared for hard work by welding, are in the form of cored wire or electrodes. In this research die... 

    The Effect of Heat Treatment and Alloying Elements on Microstructure and Wear Resistance of Hadfield Steels

    , M.Sc. Thesis Sharif University of Technology Galin Moghaddam, Emad (Author) ; Varahram, Naser (Supervisor) ; Davami, Parviz (Supervisor)
    Hadfiled steel was invented by Sir Robert Hadfield in 1882. Different types of this steel have been used widely in cement industry, mining, drilling and railroad ways due to its high toughness, high work hardening capacity and excellent wear resistance. Since the wear life of machineries and parts used in such industries is short and costly, time consuming service of the wear parts, there have been a lot of interest to increase wear resistance of austenitic manganese steels in recent years. In this study a new type of austenitic manganese steels with high carbon-high vanadium and high tungsten content has been introduced and effect of carbon, vanadium and tungsten on microstructure, micro... 

    The Effect of SiC Addition on Wear Propertion of Aluminum Piston Alloy(A356), produced by Electromagnetic Stir Casting

    , M.Sc. Thesis Sharif University of Technology Asgharzadeh Ajirlou, Farzad (Author) ; Abachi, Parvin (Supervisor) ; Varahram, Naser (Supervisor)
    One of the most important applications of aluminum alloys is the automobile's piston, which is affected by wear and tension. Nowadays, the addition of abrasion-resistant particles to molten metal and the production of composite pieces has been considered industrially. In this research, composites of A356/SiC (3, 8 and 12 %wt.) were producted by electromagnetic stir casting. In this study, after optimizing the stir casting conditions for the production of samples, the influence of electromagnetic stirrer on the microstructure and distribution of particles in the melt was studied. Moreover effect of adding SiC particles on abrasion behavior of A356 alloy was checked. Electromagnetic stirring... 

    An Investigation on in-situ Synthesis and Wear Behavior of Al-Al3Ti Nanocomposite Produced via Mechanical Alloying/Hot-Press Technique

    , M.Sc. Thesis Sharif University of Technology Hejazi Dehaghani, Mohammad Mehdi (Author) ; Maddah Hosseini, Hamid Reza (Supervisor)
    In the present investigation, the mechanical alloying (MA) technique was employed to produce nanocrystalline Al-Ti alloys. Elemental Al and Ti powders were mixed with different compositions (0, 5, 10, and 20 wt.% Ti) and then, milled in a planetary ball-mill up to 40 h. The variations of powder morphology and particle size, apparent and tap densities, microstructure, grain size, lattice strain, and microhardness were studied with increasing the milling time. While dissolution of Ti in the Al matrix resulted to the formation of supersaturated Al-Ti solid solution in the samples containing 5 and 10 wt.% Ti, the specimen with 20 wt.% Ti, eventually, led to nanocomposite powder with different... 

    Bioactivity of Surface Modified Titanium Alloy Ti-6Al-4V ELI by Pack Siliconizing in Simulated Body Fluid

    , M.Sc. Thesis Sharif University of Technology Rezvani, Alireza (Author) ; Ekrami, Ali Akbar (Supervisor) ; Ziaei Moayyed, Ali Akbar (Supervisor)
    Titanium alloy Ti-6Al-4V ELI with high biocompatibility and corrosion resistance, has a lot of applications in biomedical engineering. Disadvantage of this alloy is it’s disability to create a fast and good contact with the host/bone environment, after implanting in the body. Beside that it has low wear resistance. Nowadays to optimize the wear resistance, bioactivity and osteoconduction of surface of implants which are made from this alloy, the surface morphology are optimized in size and distribution. Different surface treatments are used for producing rough and porous surfaces to improve bioactivity along with wear resistance. In this study, surface modification of Ti-6Al-4V ELI was done... 

    Fabrication and Microstructual Study of Ti/TiC Composite Coating on CP-Ti by Using Various Cored Wires and TIG

    , M.Sc. Thesis Sharif University of Technology Monfared, Amir (Author) ; Kokabi, Amir Hossein (Supervisor) ; Asgari, Sirous (Supervisor)
    Tungsten Inert Gas (TIG) process and different cored wires that were filled separately with nano TiC particles, micro TiC particles and graphite powders were employed to produce surface composite coating on CP-Ti substrate to improve wear resistance. At first using titanium strips, wire drawing process and different powders various cored wires were produced and then using TIG, these cored wires were coated on CP-Ti. This process was done for different current intensities and velocities. Composite coating tracks were found to be affected by the TIG heat input and the kinds of the cored wires. The microstructures of the surface composite coating showed phases of α'-Ti and primary and dendritic... 

    Fabrication of high wear resistant Al/Al3Ti metal matrix composite by in situ hot press method

    , Article Materials and Design ; Volume 30, Issue 2 , 2009 , Pages 280-286 ; 02641275 (ISSN) Nofar, M ; Madaah Hosseini, H. R ; Kolagar Daroonkolaie, N ; Sharif University of Technology
    In this study, hot press method has been used to fabricate Al/Al3Ti composite. In situ reacted Al3Ti compound is formed through Al and TiO2 powder blend in order to enhance mechanical properties and mainly wear resistance. After homogeneous blending of Al and TiO2, hot pressing was performed at 580 °C at different durations and pressures. Scanning electron microscopy was used for microstructural survey. Density measurements using Archmede's method and Brinell hardness test were carried out for all the samples. By increasing the hot pressing pressure, both density and hardness increased significantly. On the other hand, by increasing the time, hardness increased and density decreased due to... 

    Effect of heat treatment cycle on the mechanical properties of machinable austempered ductile iron

    , Article 16th International Metallurgical and Materials Conference, METAL 2007, 22 May 2007 through 24 May 2007 ; 2007 Tadayon Saidi, M ; Baghersaee, N ; Varahram, N ; Hanumantha Rao, M ; Rao, G. V.S. N ; Sharif University of Technology
    TANGER spol. s r.o  2007
    ADI have been used for a wide variety of application in automotive,rail,and heavy engineering industry because of its excellent mechanical properties such as high strength with good ductility,good wear resistance,and good fatigue properties. The properties of austempered ductile iron are dependent on both chemistry and heat treatment, which has lead to invention of MADI (machinable austempered ductile iron). MADI is a new class of ductile iron with superior mechanical property than regular ductile iron with the same machinability characteristic. In this study Different cycles of austempering process (austenitization and austempering cycle) applied Due to the effect of heat treatment cycle on... 

    Dry sliding wear behavior of SiCP/QE22 magnesium alloy matrix composites

    , Article Materials Science and Engineering A ; Volume 435-436 , 2006 , Pages 653-657 ; 09215093 (ISSN) Abachi, P ; Masoudi, A ; Purazrang, K ; Sharif University of Technology
    In present work, an attempt has been made to investigate the wear behavior of particle reinforced composites based on one of the proper magnesium alloys. The SiCP/QE22 composites and QE22 unreinforced specimens were produced via the powder metallurgy route. The volume fractions of SiC particles with three different shapes, i.e. sharp, blocky and round, were selected in the range of 10-25 vol.%. The dry sliding tests were conducted on unreinforced matrix and SiCP/QE22 composites using pin-on-disk apparatus, according to ASTM G99-95a standard. The applied loads were selected as 3, 5 and 20 N. The tests were carried out under sliding speeds of 0.5 and 1.2 m/s. In all tests, the sliding...