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Hydroxy Apatite/Titania Nanostructure Biocoating on Ti-6Al-4V Alloy by Sol-Gel Dip-Coating
, M.Sc. Thesis Sharif University of Technology ; Faghihi Sani, Mohammad Ali (Supervisor)
Abstract
Ceramic coatings on metallic substrates are used in many different applications. In biomaterials science, hydroxyapatite coating due to its similarity to the mineral part of bone structure is used to modification of implants surface. In this research, the HA/TiO2 double layer was coated on Ti-6Al-4V by sol- gel dip-coating method. After preparation of stable TiO2 sol, the Ti-6Al-4V substrate was dipped into the TiO2 sol. The speed of dipping was 10cm/min. After drying at 80°C, the TiO2 layer heat-treated at different temperature (350-500°C) for 1h. The HA outer layer was coated by dipping of Ti-6Al-4V substrate with TiO2 layer into HA sol, followed by heat-treatment at different temperatures...
Loading of Drug and Nanostructured Coating on Dental Implant
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhaad, Khatiboleslam (Supervisor)
Abstract
The aim of this project is to load analgesic drug; Paracetamol on dental implant. The implant is titanium alloy (Ti-6Al-4V). There are two kinds of samples of anodized and HA coated onto anodized. They are in the shape of the sheets in this study. The electrodeposition and anodization carried out in order to treat the two samples. Nanotubes were formed during anodic oxidation of the samples in the 1M Ammonium sulfate (NH₄)₂SO4 and 5wt% Ammonium fluoride NH4F electrolyte. They are expected to play role of carrier for the model drug; paracetamol. The results showed that HA anodized Ti-6-4 has the ability to hold higher amounts of drug and also can keep the drug for a longer time than the...
Microstructure and Mechanical Properties of AA6061-T6/Ti6Al4V Joints by Resistance Spot Welding
, M.Sc. Thesis Sharif University of Technology ; Kokabi, Amir Hossein (Supervisor) ; Pouranvari, Majid (Supervisor)
Abstract
Titanium alloy and aluminum alloy 6061-T6 were successfully joined by resistance spot welding. The microstructure and mechanical properties of the lap joint were investigated. The microstructure of joints was inspected by OM, XRD, and SEM. The results reveal that the reaction between liquid aluminum and solid titanium were caused welding-brazing joints, which restricts the formation of IMCs. The microstructure in the aluminum side is a type of transition structure, which is considered to be the same microstructure that connects the columnar dendrite and Equiaxed dendrite in similar aluminum alloy RSW. The welding current has the most significant influence upon the tensile shear and cross...
Bioactivity of Surface Modified Titanium Alloy Ti-6Al-4V ELI by Pack Siliconizing in Simulated Body Fluid
, M.Sc. Thesis Sharif University of Technology ; Ekrami, Ali Akbar (Supervisor) ; Ziaei Moayyed, Ali Akbar (Supervisor)
Abstract
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...
Surface Treatment Effects on Fretting Fatigue Map of a Titanium Alloy
, M.Sc. Thesis Sharif University of Technology ; Adib Nazari, Saeed (Supervisor)
Abstract
In contacts, the presence of both variable loading and low-amplitude movements causes a kind of fatigue in these components called FRETTING FATIGUE. fretting fatigue has reduced the life of parts. Due to the high cost of replacing some parts in case of failure, it is necessary to take effective measures to delay this exhaustion. One of the effective solutions that can be applied is the use of coating and surface treatments in the contact areas. In this research, first, the fretting fatigue maps of Ti-6Al-4V alloy have been calculated and drawn according to the recommendations of the ASTM standard by using finite element methods. In the next step, by using experimental experiments, the damage...
Fretting Fatigue Crack Initiation Life Prediction Model in a Dovetail Joint of a Compressor
, Ph.D. Dissertation Sharif University of Technology ; Adibnazari, Saeed (Supervisor)
Abstract
Fretting fatigue is one of the main factors leading to failure in structures that have components temporarily connected to each other. The occurrence of fretting at the connection region of a structure under cyclic loading is inevitable, and only various methods can delay its occurrence or minimize the damage resulting from it. Fretting is dependent on various factors, and this has made previous studies unable to lead to a unified approach for predicting the fretting fatigue crack initiation life. In this thesis, after reviewing previous studies, a proving ring is designed for fretting fatigue testing. In the next step, fretting fatigue tests using the bridge-type method are performed on...
Effect of Interlayer Prepared by Plasma Electrolytic Oxidation in Joint of Ti6Al4V and Al6061-t6 by Friction Stir Welding
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
Connecting titanium and aluminum alloys is widely used in different industries such as transportation, chemical, aircraft manufacturing, etc. Friction stir welding is one of the methods of joining these two metals. In order to obtain a sound joint, the formation of intermetallic phases in the interface must be controlled. One of the ways to control these phases is the use of an interlayer, which in this research is the interlayer applied by plasma electrolytic oxidation method with different current densities and coating times. In this regards, first the optimal parameters of friction stir welding were determined. Then, Ti6Al4V and Al6061-t6 welding was performed in the presence of...
The effect of multiple surface treatments on biological properties of Ti-6Al-4V alloy
, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Vol. 45, issue. 10 , 2014 , p. 4588-4593 ; Amini, P ; Asgari, S ; Sharif University of Technology
Abstract
In this research, the effect of various surface treatments including laser processing, grit blasting and anodizing on chemical structure, surface topography, and bioactivity of Ti-6Al-4V was investigated. Six groups of samples were prepared by a combination of two alternative laser processes, grit blasting and anodizing. Selected samples were first evaluated using microanalysis techniques and contact roughness testing and were then exposed to in vitro environment. Scanning electron microscopy was used to characterize the corresponding final surface morphologies. Weight measurement and atomic absorption tests were employed for determination of bioactivity limits of different surface...
Preparation and characterization of multi-walled carbon nanotube/hydroxyapatite nanocomposite film dip coated on Ti-6Al-4V by sol-gel method for biomedical applications: An in vitro study
, Article Materials Science and Engineering C ; Volume 33, Issue 4 , 2013 , Pages 2002-2010 ; 09284931 (ISSN) ; Hooshmand, T ; Mohammadi, M ; Najafi, F ; Sharif University of Technology
2013
Abstract
In the present research, the introduction of multi-walled carbon nanotubes (MWCNTs) into the hydroxyapatite (HA) matrix and dip coating of nanocomposite on titanium alloy (Ti-6Al-4V) plate was conducted in order to improve the performance of the HA-coated implant via the sol-gel method. The structural characterization and electron microscopy results confirmed well crystallized HA-MWCNT coating and homogenous dispersion of carbon nanotubes in the ceramic matrix at temperatures as low as 500 C. The evaluation of the mechanical properties of HA and HA/MWCNT composite coatings with different weight percentages of MWCNTs showed that the addition of low concentrations of MWCNTs (0.5 and 1 wt.%)...
Investigation of the effect of Al-5Ti-1B grain refiner on dry sliding wear behavior of an Al-Zn-Mg-Cu alloy formed by strain-induced melt activation process
, Article Materials and Design ; Volume 46 , 2013 , Pages 766-775 ; 02641275 (ISSN) ; Aghdam, B. G ; Rahnoma, H. E ; Emamy, M ; Sharif University of Technology
2013
Abstract
This study was undertaken to investigate the influence of Al-5Ti-1B master alloy and modified strain-induced melt activation process on the structural characteristics, mechanical properties and dry sliding wear behavior of Al-12Zn-3Mg-2.5Cu aluminum alloy. The optimum amount of Ti containing master alloy for proper grain refining was selected as 2. wt.%. The alloy was produced by modified strain-induced melt activation (SIMA) process. Reheating condition to obtain a fine globular microstructure was optimized. The optimum temperature and time in strain-induced melt activation process are 575. °C and 20. min, respectively. T6 heat treatment was applied for all specimens before tensile testing....
Single and double stage sintering of mechanically alloyed powder for nanostructured Ti6Al4V foams usable in cancellous scaffolds
, Article International Heat Treatment and Surface Engineering ; Volume 7, Issue 1 , 2013 , Pages 43-48 ; 17495148 (ISSN) ; Aryana, M ; Hassanzadeh Nemati, N ; Alizadeh, M ; Ebadifar, A ; Sharif University of Technology
2013
Abstract
Mechanical alloying and sintering were used to fabricate nanostructured Ti6Al4V scaffolds of highly controllable pore geometry and fully interconnected porous network. Elemental powders were milled for different periods of time (10, 20, 30, 40 and 60 h), mixed with 40-60 vol.-% of 200-400 μm cuboidal NaCl, compacted at 500-600 MPa and sintered according to single or double stage heat treatment regimes at 790 and 950°C under vacuum. After sintering, the samples were soaked in distilled water to washout the NaCl. Foamy microstructures were obtained showing well shaped biopores and fragmentary embedded micropores. The shape of initial NaCl was copied into the biopores which had highly...
Sol-gel derived hydroxyapatite coating on TiB 2/TiB/Ti substrate
, Article Surface Engineering ; Volume 28, Issue 7 , August , 2012 , Pages 526-531 ; 02670844 (ISSN) ; Dabir, F ; Taheri, M ; Sohrabi, N ; Toroghinejad, M. R ; Sharif University of Technology
2012
Abstract
The low erosion resistance of titanium and its alloys has prevented their widespread application as joint implants. In addition, one essential requirement for the implants to bond with the living bone is the formation of a bone-like apatite on their surfaces in the host body. To enhance the erosion resistance of the surface, a diffused layer of TiB2 was formed at 1000uC on the commercial pure titanium. Hydroxyapatite was then coated on the boronised titanium by means of dip coating in a sol-gel solution. In order to confirm the biocompatibility of the specimens, they were soaked in a simulated body fluid for several days. The surface morphology of the specimens after exposure was studied by...
Study the influence of ultrasonic vibration on grinding of Ti6Al4V
, Article Proceedings of the 6th International Conference on Leading Edge Manufacturing in 21st Century, LEM 2011, 8 November 2011 through 10 November 2011 ; Novembe , 2011 ; Movahhedy, M. R ; Akbari, J ; Sharif University of Technology
2011
Abstract
Titanium alloys, in particular Ti6Al4V, are increasingly used recently due to high strength-to-weight ratio, biocompatibility and robust mechanical-properties at high temperatures. However, Ti6Al4V have poor machinability because of their poor thermal conductivity and high reactivity. Usually in conventional grinding (CG) of these alloys, surface burning is unavoidable. Ultrasonic assisted grinding (UAG) is an efficient method for overcoming the poor machinability of such materials. In this research, effect of imposed vibration on grinding of Ti6Al4V is studied. Obtained results show forces and surface roughness are reduced 18% and 12% by UAG comparing to CG respectively. It also results in...
High temperature deformation and processing map of a NiTi intermetallic alloy
, Article Intermetallics ; Volume 19, Issue 10 , October , 2011 , Pages 1399-1404 ; 09669795 (ISSN) ; Aboutalebi, M ; Kheirandish, S ; Karimi Taheri, A ; Abbasi, S. M ; Sharif University of Technology
2011
Abstract
The deformation behavior of a 49.8 Ni-50.2 Ti (at pct) alloy was investigated using the hot compression test in the temperature range of 700 °C-1100 °C, and strain rate of 0.001 s-1 to 1 s-1. The hot tensile test of the alloy was also considered to assist explaining the related deformation mechanism within the same temperature range and the strain rate of 0.1 s-1. The processing map of the alloy was developed to evaluate the efficiency of hot deformation and to identify the instability regions of the flow. The peak efficiency of 24-28% was achieved at temperature range of 900 °C-1000 °C, and strain rates higher than 0.01 s -1 in the processing map. The hot ductility and the deformation...
A study on the hot workability of wrought NiTi shape memory alloy
, Article Materials Science and Engineering A ; Volume 528, Issue 18 , July , 2011 , Pages 5656-5663 ; 09215093 (ISSN) ; Kheirandish, S ; Aboutalebi, M ; Taheri, A. K ; Abbasi, S. M ; Sharif University of Technology
2011
Abstract
The hot workability of a wrought 49.8 Ni-50.2 Ti (at pct) alloy was assessed using the hot compression tests in temperature range of 700-1000°C, strain rate of 0.001-1s-1, and the total strain of 0.7. The constitutive equations of Arrhenius-type hyperbolic-sine function was used to describe the flow stress as a function of strain rate and temperature. The preferable regions for hot workability of the alloy were achieved at Z (Zener-Holloman parameter) values of about 109-1013 corresponding to the peak efficiency of 20-30% in the processing map. However, a narrow area in the processing map including the deformation temperature of 1000°C and strain rate of 1s-1 is inconsistent with the related...
Neural network prediction of mechanical properties of porous NiTi shape memory alloy
, Article Powder Metallurgy ; Volume 54, Issue 3 , Nov , 2011 , Pages 450-454 ; 00325899 (ISSN) ; Hafizpour, H. R ; Sadrnezhaad, S. K ; Akhondzadeh, A ; Abbasi Gharacheh, M ; Sharif University of Technology
2011
Abstract
A multilayer back propagation learning algorithm was used as an artificial neural network tool to predict the mechanical properties of porous NiTi shape memory alloys fabricated by press/sintering of the mixed powders. Effects of green porosity, sintering time and the ratio of the average Ti to Ni particle sizes on properties of the product were investigated. Hardness and tensile strength of the compacts were determined by hardness Rockwell B method and shear punch test. Three-fourths of 36 pairs of experimental data were used for training the network within the toolbox of the MATLAB software. Porosity, sintering time and particle size ratios were defined as the input variables of the model....
Hydrogen desorption properties of MgH2-TiCr1.2Fe 0.6 nanocomposite prepared by high-energy mechanical alloying
, Article Journal of Power Sources ; Volume 196, Issue 10 , 2011 , Pages 4604-4608 ; 03787753 (ISSN) ; Kaflou, A ; Simchi, A ; Sharif University of Technology
Abstract
In the present work, high-energy mechanical alloying (MA) was employed to synthesize a nanostructured magnesium-based composite for hydrogen storage. The preparation of the composite material with composition of MgH2-5 at% (TiCr1.2Fe0.6) was performed by co-milling of commercial available MgH2 powder with the body-centered cubic (bcc) alloy either in the form of Ti-Cr-Fe powder mixture with the proper mass fraction (sample A) or prealloyed TiCr1.2Fe0.6 powder (sample B). The prealloyed powder with an average crystallite size of 14 nm and particle size of 384 nm was prepared by the mechanical alloying process. It is shown that the addition of the Ti-based bcc alloy to magnesium hydride yields...
Synthesis of a nanostructured MgH2-Ti alloy composite for hydrogen storage via combined vacuum arc remelting and mechanical alloying
, Article Materials Letters ; Volume 65, Issue 7 , 2011 , Pages 1120-1122 ; 0167577X (ISSN) ; Kaflou, A ; Simchi, A ; Sharif University of Technology
Abstract
To improve the hydrogen kinetics of magnesium hydride, TiCr 1.2Fe0.6 alloy was prepared by vacuum arc remelting (VAR) and the alloy was co-milled with MgH2 to process nanostructured MgH2-5 at.% TiCr1.2Fe0.6 powder. The hydrogen desorption properties of the composite powder were studied and compared with pure magnesium hydride. X-ray diffraction (XRD) analysis showed that the composite powder prepared by VAR/mechanical alloying (MA) procedure consisted of β-MgH2, γ-MgH2, bcc Ti-Cr-Fe alloy, and small amount of MgO. The average size of particles and their grain structure after 4 h MA were determined by a laser particle size analyzer and XRD method and found to be 194 nm and 11 nm,...
Friction stir processing of an aluminum-magnesium alloy with pre-placing elemental titanium powder: In-situ formation of an Al3 Ti-reinforced nanocomposite and materials characterization
,
Article
Materials Characterization
;
Volume 108
,
October
,
2015
,
Pages 102-114
;
10445803 (ISSN)
; Simchi, A
; Kokabi, A. H
; Gerlich, A. P
;
Sharif University of Technology
Elsevier Inc
2015
Abstract
A fine-grained Al-Mg/Al3 Ti nanocomposite was fabricated by friction stir processing (FSP) of an aluminum-magnesium (AA5052) alloy with pre-placed titanium powder in the stirred zone. Microstructural evolutions and formation of intermetallic phases were analyzed by optical and electron microscopic techniques across the thickness section of the processed sheets. The microstructure of the nanocomposite consisted of a fine-grained aluminum matrix (1.5 μm), un-reacted titanium particles (<40 μm) and reinforcement particles of Al3 Ti (<100 nm) and Mg2 Si (<100 nm). Detailed microstructural analysis indicated solid-state interfacial reactions between the aluminum...
The influence of surface nanocrystallization induced by shot peening on corrosion behavior of niti alloy
, Article Journal of Materials Engineering and Performance ; Volume 24, Issue 8 , August , 2015 , Pages 3093-3099 ; 10599495 (ISSN) ; Sadrnezhaad, S. K ; Atai, M ; Sharif University of Technology
Springer New York LLC
2015
Abstract
Nickel-titanium (NiTi) shape memory alloys have been widely used as implant materials, due to their superior shape memory properties and similar mechanical behavior to bone tissue. The presence of nickel on the surface of nickel-titanium alloy and release of this ion in the body environment will result in some allergic reactions. In current study, we used shot pinning process to produce nanocrystalline nickel-titanium alloy with increased corrosion resistance. Field emission scanning electron microscopy (FE-SEM), x-ray diffraction (XRD) analysis, and atomic force microscopy were employed to investigate the surface features of samples. The quantitative chemical analysis of NiTi and modified...