Loading...
Search for:
abrasivity
0.004 seconds
Total 29 records
Improvement of dry sliding tribological properties of polyamide 6 using diamond nanoparticles
, Article Tribology International ; Volume 115 , 2017 , Pages 370-377 ; 0301679X (ISSN) ; Shojaei, A ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
In the present study, it was revealed that incorporation of nanodiamond containing carboxylic group (ND-COOH) decreased considerably specific wear rate (∼30%) and COF (∼60%) of polyamide 6 (PA6) at 1 wt% loading. Compared with ND-COOH, amino functionalized ND enhanced further wear performance of PA6 which was associated with its finer dispersion as well as greater influence on the improvement of mechanical properties, toughness and crystallinity of PA6. Surface temperature increment caused by frictional heat was in close agreement with COF and wear characteristics of the samples. Optical microscopy images revealed that NDs promote the abrasive wear mechanism in PA6/ND composites. © 2017...
A new analysis method of the dry sliding wear process based on the low cycle fatigue theory and the finite element method
, Article Journal of Materials Engineering and Performance ; Vol. 23, issue. 3 , 2014 , pp. 1096-1106 ; ISSN: 10599495 ; Taheri, A. K ; Bakhtiarydavijani, A ; Sharif University of Technology
Abstract
In the present work, a combination of a dynamic explicit finite element model and the low cycle fatigue theory is used to simulate the steady-state abrasive wear occurring between an as-cast eutectoid steel and a carbide-tungsten disk. While the low cycle fatigue theory has been used to model wear in softer non-ferrous alloys, this work shows its applicability and accuracy for use in harder alloys, such as the eutectoid steel used in this research which is strengthened with added chromium. The novelty of this work lies in calculating the Manson-Coffin relation constants from a coupled finite element model with experimental tests instead of the previously used Slip line method. The D...
The effect of water-cement ratio in compressive and abrasion strength of the nano silica concretes
, Article World Applied Sciences Journal ; Volume 17, Issue 4 , 2012 , Pages 540-545 ; 18184952 (ISSN) ; Rahmani, K ; Peroti, S ; Rahemi, L ; Sharif University of Technology
2012
Abstract
Development and construction of hydraulic structures like dams, the concrete durability in these kinds of structures has gained special attention. One of the crucial factor in concrete technology is it durability in hydraulic structures. Concrete has to resist against abrasion due to the crash of particles carried by water. To enhance the abrasion resistance of concrete different methods have been offered. In the present stud, the role of water-cement ratio in compressive and abrasion strength of nano silica concrete was investigated. The constructed concrete samples with 3% nano silica and water-cement ratios of 0.33, 0.36, 0.40, 0.44 and 0.50 were experimented. Other design features...
Effect of water-cement ratio on abrasive strength, porosity and permeability of nano-silica concrete
, Article World Applied Sciences Journal ; Volume 17, Issue 8 , 2012 , Pages 929-933 ; 18184952 (ISSN) ; Peroti, S ; Rahmani, K ; Rahemi, L ; Sharif University of Technology
2012
Abstract
Today, due to rapid development of construction of hydraulic structures like dams, the constituent material used in concrete and its durability in these kinds of structures has gained dominant interests and importance. One of the important factors of concrete durability in these structures is its resistance against abrasion due to crash of particles carried out as hydrated crystalline particulate matter. To enhance the abrasion resistance of concrete, different methods have been offered and investigated by many research3ers/ The aim of present article is to investigate the important parameter i.e. water-cement ratio on abrasive strength, porosity and the coefficient of hydraulic conductivity...
Analysis of the effect of kevlar fibers on abrasion resistance, flexural strength and hydraulic conductivity coefficient of silica fume concretes
, Article Iranian Journal of Science and Technology - Transactions of Civil Engineering ; Volume 44, Issue 2 , 2020 , Pages 669-674 ; Piroti, S ; Ghameian, M ; Sharif University of Technology
Springer
2020
Abstract
Reinforcing fiber and silica fume of concrete can be considered as one of the most widely used additives. In this study, with a review of the history and advantages of using silica fume and polypropylene fibers in concrete, 380 concrete laboratory samples were constructed, of which 25 mixing designs with water–cement ratio of 0.35 and fiber content of 0.2, 0.3, 0.4 and 0.5 of concrete volume and 7% silica fume were prepared according to the ACI standard in their manufacturing. In the present research, samples of Kevlar fiber containing silica fume were tested under flexural strength, abrasion resistance and hydraulic conductivity coefficient. According to achieved results, the optimum amount...
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 ; Kazerani, V ; Ghorashi, M. S ; Sharif University of Technology
Abstract
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,...
FEM analysis of single grit chip formation in creep-feed grinding of Inconel 718 superalloy
, Article Advanced Materials Research, 18 September 2011 through 21 September 2011, Stuttgart ; Volume 325 , 2011 , Pages 128-133 ; 10226680 (ISSN) ; 9783037852316 (ISBN) ; Akbari, J ; Sharif University of Technology
2011
Abstract
Recent advances in materials science have necessitated the development and understanding of manufacturing processes for safe and repeatable utilization. Grinding is shown to be a promising material removal process especially for brittle and hard to cut materials such as superalloys. Grinding has always been associated with analysis and modeling complications regarding its nature which has limited its extension and reliability of use. The first step in analysis of grinding is considering the action of a single abrasive grit on workpiece surface. In this work the action of a single CBN abrasive grit in creep-feed grinding process of Inconel 718 superalloy is modeled and analyzed using a 3D FEM...
Al2O3/Si3N4 nanocomposite coating on aluminum alloy by the anodizing route: Fabrication, characterization, mechanical properties and electrochemical behavior
, Article Ceramics International ; 2016 ; 02728842 (ISSN) ; Afshar, A ; Ahmadi, S ; Sharif University of Technology
Abstract
An Al2O3/Si3N4 nanocomposite coating was successfully fabricated on commercial aluminum alloy. Hardness measurements, polarization and electrochemical impedance spectroscopy (EIS) were employed to study the mechanical and corrosion behaviors of the coatings. Field-Emission Scanning Electron Microscopy (FE-SEM) equipped with Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) were utilized to characterize the surface morphology and phase composition of the coatings. Also, coatings abrasive wear properties were evaluated with a modified ASTM G105 standard. FE-SEM image, EDS and XRD analysis revealed the presence of Si3N4 in the coating. Furthermore, the results showed hardness of...
Study of the Effect of Molybdenum on Wear Properties and Mechanical Properties of Claded Manganese Steel Created with the Cored Wired Filler Metal
, M.Sc. Thesis Sharif University of Technology ; Kokabi, Amir Hossein (Supervisor) ; Davami, Parviz (Co-Advisor)
Abstract
Hadfield’s manganese steel, nominally Fe–1.2%C–13%Mn, is an alloy with inherent toughness, work-hardening characteristics and excellent resistance to some types of adhesive and abrasive wear. However, due to its low yield strength, it may be deformed markedly before its work-hardening become effective. There have been many studies on increasing strenght by alloying manganese steel, but the effects some other alloying additions such as 1 to 2 percent Al, Cr, W, V despite increase strenght and wear resistance at the low stress abrasive condition, decrease work-hardening characteristics and wear resistance at the high stress abrasive condition. The aim of present work, is to modify...
Wear Behavior of Cast Rods Manufactured for Hard Surfacing Iron Based Alloy
, M.Sc. Thesis Sharif University of Technology ; Kokabi, Amir Hossein (Supervisor) ; Varahram, Naser (Supervisor)
Abstract
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...
Electrophoretic Deposition of Ni/SiO2 Nanocomposite Coating: Fabrication Process and Tribological and Corrosion Properties
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
Ni/SiO2 nanoparticle composite coatings were prepared by electrophoretic deposition (EPD) and their hardness, wear and corrosion resistance were examined. Additionally, the morphology of the coatings was observed. In the first phase, the feasibility of coating with Scanning Electron Microscopy (SEM) as well as X-ray diffraction (XRD) and Energy Dispersive Spectra (EDS) techniques was evaluated. After finding the effect of concentration of nanoparticles on coating characteristics and the results of using SEM, optimum conditions for uniform coating, acceptable adhesion at 20V and concentrations of 10 g/L for Ni, 1.2 g/L for SiO2, and choosing NiCl2 as additive with a concentration of 0.2 g/L...
Impact-abrasion wear characteristics of in-situ VC-reinforced austenitic steel matrix composite
, Article Materials Science and Engineering A ; Volume 585 , 2013 , Pages 422-429 ; 09215093 (ISSN) ; Karimzadeh, N ; Varahram, N ; Davami, P ; Sharif University of Technology
2013
Abstract
In this investigation, in-situ precipitation of vanadium carbides was employed to reinforce Fe-13Mn and Fe-13Mn-3W alloys by means of conventional melting and casting route. Microstructures were characterized by optical and scanning electron microscopy techniques.Mechanical properties of the materials were determined by hardness, impact toughness and tension tests. It was observed that tungsten improved the strength of the matrix and the reinforcements as well as tensile properties and work hardening rate of the VC-reinforced composite. Ball mill abrasion test was utilized to simulate impact-abrasion wear condition using two types of abrasive minerals. The results showed that the degree of...
Mechanical and surface properties of e-beam irradiated polytetrafluoroethylene-silicone rubber composites
, Article Polymers and Polymer Composites ; Volume 18, Issue 6 , 2010 , Pages 329-336 ; 09673911 (ISSN) ; Kashcooli, Y ; Frounchi, M ; Sharif University of Technology
2010
Abstract
Compounding electron beam irradiated polytetrafluoroethylene (PTFE or Teflon) powder with silicone rubber produced silicone rubber/PTFE composites with desired physical properties. PTFE powder was exposed to electron beam irradiation at various doses and characterized by FTIR, DSC and contact angle measurements. Irradiation of PTFE with high energy electron beam induced chain scission reactions. Irradiated PTFE showed higher degree of crystallization and lower melting point with increasing absorbed dose. Number average molecular weight of irradiated PTFE was reduced significantly at higher absorbed doses. Formation of polar groups on the surface of irradiated PTFE powder was detected by FTIR...
Preparation of Composite Coating with ZrO2 Nanoparticles on Mg alloy using AC Plasma Electrolyte Oxidation
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
Plasma electrolytic oxidation (PEO) was implemented to produce a ceramic coating on AZ31 magnesium alloy, using an alternate power source (AC), in a silicate based electrolyte containing zirconia nanoparticles in different concentrations. Prior to adding nanoparticles to electrolyte, working parameters such as current density, frequency and coating duration were examined and studied concerning the equipment and coating conditions. And after reaching the optimized condition, ZrO2 nanoparticles were added to the electrolyte to create composite coatings. To examine the properties of the coatings before and after the creation of composite PEO coatings, scanning electron microscopy (SEM) was used...
Investigation of the effect of tungsten substitution on microstructure and abrasive wear performance of in situ vc-reinforced high-manganese austenitic steel matrix composite
, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 44, Issue 8 , 2013 , Pages 3826-3835 ; 10735623 (ISSN) ; Karimzadeh, N ; Varahram, N ; Davami, P ; Sharif University of Technology
2013
Abstract
Particulate VC-reinforced high-manganese austenitic steel matrix composites with different vanadium and tungsten contents were synthesized by conventional alloying and casting route. Microstructural characterizations showed that the composites processed by in situ precipitation of the reinforcements were composed of V8C7 particulates distributed in an austenitic matrix. It was observed that addition of tungsten to austenite increases work-hardening rate of subsurface layer during pin-on disk wear test. The maximum abrasive wear resistance was achieved at tungsten content equal to 2 wt pct. However, excessive addition of tungsten promoted the formation of W 3C phase and reduced the abrasive...
Taguchi's optimization in ultrasonic drilling of alumina ceramic
, Article Proceedings of the 6th International Conference on Leading Edge Manufacturing in 21st Century, LEM 2011, 8 November 2011 through 10 November 2011 ; November , 2011 ; Akbari, J ; Japan Society of Mechanical Engineers (JSME),; Manufacturing and Machine Tool Division ; Sharif University of Technology
2011
Abstract
This paper outlines the effectiveness of the ultrasonic machining of alumina in terms of tool wear rate of the tool used and the material removal rate of work piece produced. The optimum combination of various input factors as type of abrasive slurry, their size and concentration, power and feed rate, in the machining of alumina has been determined by applying the Taguchi technique, also analysis is used to choose the best shape for horn. The study shows that among input parameters, power has the highest effect on MRR (material removal rate). Effects of grit size and feed rate on TWR (tool wear rate) also investigated
Wear wear properties of rheo-squeeze cast aluminum matrix reinforced with nano particulates
, Article Protection of Metals and Physical Chemistry of Surfaces ; Volume 52, Issue 3 , 2016 , Pages 486-491 ; 20702051 (ISSN) ; Heydari, F ; Tofigh, A. A ; Rahimipour, M. R ; Razavi, M ; Mazahery, A ; Davami, P ; Sharif University of Technology
Maik Nauka Publishing / Springer SBM
Abstract
There are many approaches to fabricate nanoparticles reinforced aluminum matrix composites. However, uniform distribution of nanoparticle within aluminum matrix remains a difficult challenge. In this study, a novel method is used by taking the advantages from squeeze casting of semi-solid aluminum slurry combined with electromagnetic field to refine the microstructure of the primary Al and eutectic Si phase, plus to obtain uniform distribution nano alumina particles in the aluminum matrix. It is noted that electromagnetic field plays an important role in the formation of non-dendritic primary α-Al particles and a great microstructure refinement occurs as a consequence of the pressure...
The effect of different rare earth elements content on microstructure, mechanical and wear behavior of Mg-Al-Zn alloy
, Article Materials Science and Engineering A ; Volume 527, Issue 7-8 , 2010 , Pages 2027-2035 ; 09215093 (ISSN) ; Masoudi, A ; Khomamizadeh, F ; Sharif University of Technology
2010
Abstract
The effect of Rare earths addition to AZ91 magnesium alloy and its influence on the microstructure and mechanical properties was investigated in this study. Addition of cerium rich misch metal to AZ91 alloy resulted in formation of needle shape particles, which had a very high thermal stability, providing superior mechanical properties compared to AZ91 magnesium alloy. As a result, the grain boundaries were less susceptible for grain boundary sliding at high temperatures. The steady state creep rates were specified and for the AZ91 alloy and the results indicate a mixed mode of creep behavior, with some grain boundary effects contributing to the overall behavior. However for the RE added...
Conditioning of Vitrified Bond CBN grinding wheels using a picosecond laser
, Article Advanced Materials Research ; Vol. 1017, issue , 2014 , p. 573-579 ; Tawakoli, T ; Akbari, J ; Azarhoushang, B ; Sharif University of Technology
Abstract
Laser ablation is a novel non-mechanical wheel preparation method for optimizing the treatment costs of superabrasive tools. In this study the thermal effects of picosecond laser radiation on CBN superabrasive grinding wheel surface is analytically and experimentally investigated. The analytical approach is intended to find threshold process parameters for selective ablation of cutting grains and bond material. It has been analytically and experimentally shown that, the extent of material degradation is defined by the maximum surface temperature induced by the laser radiation which is in turn defined by the laser beam energy. It is also suggested that, the depth of laser thermal effects is...
On the comparison of microstructural characteristics and mechanical properties of high-vanadium austenitic manganese steels with the Hadfield steel
, Article Materials Science and Engineering A ; Volume 532 , 2012 , Pages 260-266 ; 09215093 (ISSN) ; Varahram, N ; Davami, P ; Sharif University of Technology
Abstract
In this study, high-vanadium austenitic manganese steel (HV-AMS) alloys and the standard Hadfield steel were investigated. The microstructure of these high-vanadium alloyed Hadfield steels was studied thoroughly using optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) and was compared to the Hadfield steel. The hardness and unnotched Charpy impact strength of HV-AMS alloys and Hadfield steel were examined at ambient temperature in the as-cast and heat-treated conditions. A pin-on-disk wear test at linear speed of 10. m/min and a 55. N normal load was employed to evaluate the wear behavior of both steel samples. Microstructural results showed that varying...