Loading...
Search for:
functionally-graded-coatings
0.011 seconds
Synthesis of Antibacterial Hydroxyapatite/Titania-Silver Coating on Titanium Substrate Using Sol-Gel Method
, M.Sc. Thesis Sharif University of Technology ; Afshar, Abdollah (Supervisor)
Abstract
With the increase in the average age of the world's population, osteoporosis is a worldwide incidence. This disease, along with natural disasters, are important factors in the occurrence of fractures in various bones of the body. One of the methods for solving this problem and replacing with broken body bones is the use of metal implants with hydroxyapatite-based coatings. One of the common problems with using implants in the body is the infection in the adjacent parts of the implant. To overcome this problem, several studies have been carried out on the use of hydroxyapatite coatings with metal ions or antibacterial oxide compounds. In the present study, the influence of factors such as the...
Investigating Effect of Nano Ceramic Coating of Combustion Chamber on the Performance of Internal Combustion Engines
,
M.Sc. Thesis
Sharif University of Technology
;
Naghdabadi, Reza
(Supervisor)
Abstract
Thermal barrier coatings (TBCs) are used for increasing the efficiency and reducing pollutants of internal combustion engines (ICEs). In this paper, an optimization framework is developed in order to obtain the optimal dimensions for conventional coat, and the optimal dimensions and material property for functionally graded (FG) coat of a partially coated piston. A thermo mechanical analysis is investigated for Nano coat by finite element method. The conventional and Nano coats are made of MgZrO_3 as the insulating ceramic overlay and NiCrAl as the metallic bond-coat. The properties of the FG coat is assumed to vary according to power law through the thickness. For all tree conventional, FG...
Stress intensity factors of multiple axisymmetric interface cracks in an isotropic layer with FGM coating under torsional loading
, Article Multidiscipline Modeling in Materials and Structures ; Volume 15, Issue 6 , 2019 , Pages 1352-1365 ; 15736105 (ISSN) ; Pourseifi, M ; Rezaei, S ; Sharif University of Technology
Emerald Group Publishing Ltd
2019
Abstract
Purpose: The purpose of this paper is to provide a theoretical analysis of the fracture behavior of multiple axisymmetric interface cracks between a homogeneous isotropic layer and its functionally graded material (FGM) coating under torsional loading. Design/methodology/approach: In this paper, the authors employ the distributed dislocation technique to the stress analysis, an FGM coating-substrate system under torsional loading with multiple axisymmetric cracks consist of annular and penny-shaped cracks. First, with the aid of the Hankel transform, the stress fields in the homogeneous layer and its FGM coating are obtained. The problem is then reduced to a set of singular integral equations...
On thermoelastic fields of a multi-phase inhomogeneity system with perfectly/imperfectly bonded interfaces
, Article International Journal of Solids and Structures ; Volume 45, Issue 22-23 , 2008 , Pages 5831-5843 ; 00207683 (ISSN) ; Mohammadi Shodja, H ; Sharif University of Technology
2008
Abstract
The stress fields of cylindrical and spherical multi-phase inhomogeneity systems with perfect or imperfect interfaces under uniform thermal and far-field mechanical loading conditions are investigated by use of the Boussinesq displacement potentials. The radius of the core inhomogeneity and the thickness of its surrounding coatings are arbitrary. The discontinuities in the tangential and normal components of the displacement at the imperfect interfaces are assumed to be proportional to the associated tractions. In this work, for the problems where the phases of the inhomogeneity system are homogeneous, the exact closed-form thermo-elastic solutions are presented. These solutions along with a...
Evaluation of hot corrosion behavior of plasma sprayed thermal barrier coatings with graded intermediate layer and double ceramic top layer
, Article Surface and Coatings Technology ; Volume 288 , 2016 , Pages 36-45 ; 02578972 (ISSN) ; Javadi, A. H ; Ghasali, E ; Shahbazkhan, A ; Shakhesi, S ; Sharif University of Technology
Elsevier
2016
Abstract
In the present work, the hot corrosion behavior of two types of multilayer plasma sprayed TBC were investigated and compared with functionally graded and conventional TBCs. These kinds of multilayer coatings consisted of nano/μ alumina as a top coat on YSZ layer, a metallic bond coat and a functionally graded intermediate layer deposited between YSZ and bond coat layers. All the layers were sprayed on the Ni-base super alloy substrate. The hot corrosion resistance of the plasma sprayed coatings was examined at 1050 °C for 40 h, using a fused mixture of 45 wt% Na2SO4 + 55wt%V2O5. Before and after hot corrosion, the microstructure and phase analysis of the coating were studied using scanning...
Stress field in the thermoelastic rolling contact of graded coatings
, Article Archive of Applied Mechanics ; Volume 88, Issue 10 , 2018 , Pages 1805-1814 ; 09391533 (ISSN) ; Adibnazari, S ; Karimzadeh, A ; Sharif University of Technology
Springer Verlag
2018
Abstract
The thermoelastic rolling contact problem for an FGM-coated half plane under the plane strain deformation is studied in this paper. A rigid roller rolls over the surface of coating with constant translational velocity generating frictional heating in the slip zones of the contact patch. The material properties of the FGM vary exponentially along the thickness direction. It is assumed that the contact area consists of a central stick zone and two slip zones of the same sign. The transfer matrix method and Fourier integral transform technique are used to achieve a system of two Cauchy singular integral equations. The coupling effect of tangential traction is eliminated by adapting the...
Effects of interface conditions on thermo-mechanical fields of multi-phase nano-fibers/particles
, Article Journal of Thermal Stresses ; Volume 32, Issue 11 , 2009 , Pages 1166-1180 ; 01495739 (ISSN) ; Shodja, H. M ; Sharif University of Technology
2009
Abstract
The stress field of a multi-phase spherical/cylindrical inhomogeneity with arbitrary interface bonding conditions, subjected to both a uniform temperature change and a uniform hydrostatic tension, is presented. Imperfect bonding conditions are modeled using linear spring model and coherent interface model. In nanosize inhomogeneities, since the surface energy is not negligible with respect to the bulk energy, the effect of surface stresses is incorporated into the formulation. Accurate estimates for the thermal stresses of a functionally graded coated inhomogeneity with perfect and /~or imperfect interfaces are given. The influence of coating stiffness, coating thickness and interface...