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Showing 44 results for Wear

Akhlaghi F., Zahedi H., Sharifi M.,
Volume 1, Issue 2 (6-2004)
Abstract

In this study different volume fractions of SiC particles of various sizes were introduced into the semisolid A356 aluminum alloy by a mechanical stirrer. Then the slurry was poured into a permanent die of certain dimensions either when the metal alloy was partially solid (semisolid-semisolid or SS route) or after reheating to above the liquidus temperature of the alloy (semisolid-liquid or SL route). Both the SS and SL composite samples were solution-treated at 520°C for 8 hours followed by quenching in water at room temperature. Microstructural characterization studies have been conducted on both the SL and SS samples to quantify the effects of the size andcontent of the SiC particles as well as the solutionizing treatment on the morphology and size ofthe eutectic silicon particles and the matrix grain (globule) size. The results were rationalized in terms of the different nucleation, fragmentation, spherodization and coarsening events, which had taken place during the processing of these composites. Finally the impact of these microstructural features in improving the wear properties of the composites has been discussed.
Golazar M.a., Mostaghimi J., Coyle T.w.,
Volume 3, Issue 1 (6-2006)
Abstract

Partially stabilized zirconia (PSZ) has been proven to be an excellent candidate as a thermal barrier coating (TBe) for hot sections in, for instance, heat or internal combustion engines and gas turbine parts. The main functions of these coatings are reducing heat losses, reducing fuel consumption, increasing efficiency, and extending durability and life. One of the main problems involved is wear behavior in the development of such coatings for these applications. Using the air plasma spraying (APS) technique, conventional and nanostructured 8 wt % yttria partially stabilized zirconia (Y-PSZ) coatings were deposited on austenitic stainless steel (AISI304) disc-shaped substrates. The coated substrates were subjected to pin-on-disc wear tests, using 10 mm silicon nitride and zirconia balls as the pin. The coefficient of friction was recorded in real time. The weight loss of coated substrates was measured. Coatings were characterized before and after being subjected to wear testing by various techniques including optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX) and X-ray diffraction (XRD). Effects of various experimental parameters such as wear distance, test temperature, and counter face material were also investigated. Results obtained revealed that, regardless of experimental conditions applied, the nanostructured zirconia coating shows better wear and tribological properties than that of the conventional one.
Rigaud M., Palco S., Paransky E.,
Volume 3, Issue 1 (6-2006)
Abstract

Wear of various basic refractory materials to substitute to currently used magnesia chrome bricks has been studied, measuring matte and slag penetration and dissolution, through different cup and rotary slag tests. High magnesia with and without impregnation, magnesia graphite, magnesia-alumina spinel with and without impregnation, olivine-magnesia and olivine magnesia- graphite bricks, as well as magnesia-graphite and olivine magnesia castables, have been tested. It has been shown that carbon impregnation and graphite introduction into basic refractories are feasible ways to enhance their corrosion-dissolution and penetration resistance against fayalite as well as calcium-ferrite slags. Olivine-based refractories (castables or bricks) may be considered as viable candidates to use in copper-making furnaces. At this point, evaluation of the thermo-mechanical properties of this new class of materials is still missing.
G. H. Akbari, M. A. Sheikhi,
Volume 4, Issue 1 (6-2007)
Abstract

Abstract: Ball mills are used in the last stage of ore processing for grinding raw materials. Forged 70Cr2 alloy steel and Austempered Ductile Iron (ADI) balls are materials from which grinding balls are made for Sarcheshmeh Copper Plant (SCP) ball mills. In the present study wear and impact properties of these two kinds of balls have been investigated. Some balls randomly were selected as samples. They were cut to investigate the cross section under optical and scanning electron microscopes. The microstructure of the sample balls was studied and quantitative measurements of microstructural features were performed. The hardness of different parts of cross sections of balls was measured. The wear resistance of the balls was measured by Pin on Disc method. Repeated dropt test was employed to evaluate impact resistance of the balls. The microstructure of ADI balls consisted of bianitic matrix with graphite nodules and some retained austenite and martensite. Micro cracks and porosities in the cast structure were frequently observed. In the case of forged steel balls the microstructure composed of tempered martensite in outer area and bianitic structure with some tempered martensite in central areas. The wear and impact resistance of forged steel balls were markedly higher than those of ADI balls. The difference was consistent with the differences between the microstructures of the two kinds of balls. Cast structure with microcracks and shrinkage porosities in ADI balls gives rise to lower impact resistance.
A. Ahmadi,, H. Sarpoolaky,, A. Mirhabibi, F. Golestani-Fard,
Volume 4, Issue 3 (12-2007)
Abstract

Abstract: Dolomite based refractories are widely used in Iranian steelmaking plants. In the present research, wear and corrosion of refractories used in steel-making converter lining in Esfahan Steel Company was studied. Post-mortem analysis of refractories clarified that the wear started with oxidation of carbon followed by chemical corrosion. Iron oxide from slag reacted with calcia, resulting in formation of low melting phase, and subsequent washout process, caused the refractory corrosion onset from the hot face. In addition, the effect of aluminum as an anti-oxidant and graphite on the corrosion resistance of refractory was investigated. Tar-dolomite samples containing different amount of graphite (0, 4, 7, and 10 wt. %) were prepared in order to study their physical properties, before and after coking. SEM micrographs employed to analyze the microstructures to determine the effect of graphite and antioxidant on corrosion behavior of the refractory. Results showed that oxidation process of carbon in the system was hindered and improved corrosion resistance by introducing graphite and antioxidant into the refractory composition.
M. Kazemi Pour, S. Sharafi,
Volume 5, Issue 1 (3-2008)
Abstract

Abstract: Hardfacing is one of the most useful and economical ways to increase the service life of components subjected to abrasive wear. Iron based hardfacing alloys have long been considered as candidate coatings for wear-resistant applications in industry. In the present work two layer of Fe-34Cr-4.5C%wt hardfacing alloy was deposited on ASTM A36 carbon steel plates by SMAW method. The microstructure consists of large primary and eutectic M7C3 carbides, metastable austenite and small amount of secondary carbides. The microstructure was analyzed by optical and scanning electron microscopes. In the same condition of size, shape, distribution and volume fraction of carbides the as-welded matrix changed to martensite, tempered martensite and ferrite by heat treatment processes. The wear resistance was measured by pin-on-disk method under loads of 5, 10 and 20N and for sliding distance of 1500m. The results showed that the as-welded sample with austenitic matrix has the most and the ferritic matrix specimen has the least wear resistance. The predominate mechanisms for mass losses were determined to be micro-cutting, microploughing.
A. Poladi, M. Zandrahimi,
Volume 5, Issue 3 (9-2008)
Abstract

Abstract: Austenitic stainless steels exhibit a low hardness and weak tribological properties. The wear behaviour of austenitic stainless steel AISI 316 was evaluated through the pin on disc tribological method. For investigating the effect of wear on the changes in microstructure and resistance to wear, optical microscopy and scanning electron microscope were used. The hardness of the worn surfaces was measured with a micro-hardness tester. Worn surfaces were analyzed through X-ray diffraction. Results showed that with increasing the sliding distance and applied load, the austenite phase partially transformed to ά martensite, and there was no trace of ε phase detected. Due to the formation of probably hard and strong martensite phase, as the sliding distance and applied load increased, the hardness and the wear resistance of the material was increased. Wear mechanism was on the base of delamination and abrasion.
H. Mohammadzade, Sh. Kheirandish, H. Saghafian,
Volume 6, Issue 2 (6-2009)
Abstract

Abstract:

transition and heat affected zones formed during surface remelting (in order to improve wear resistance) with TIG

process has been investigated. Relationship between various TIG parameters and thickness of remelted and heat

affected zones revealed that a high concentrated heat energy is imposed by TIG process which makes it a proper option

for focused surface treatment. Based on microstructural examinations five areas with different microstructure and

microhardness were identified within the surface area. Graphite flakes were totally dissolved within the first area

leading to the transformation of denderitic austenite to plate martensite and the formation of ledeburite within

interdenderites. The main feature of the second area, resulted from the presence of graphite flakes, was the local

melting with a gap in the vicinity of graphite flakes and that of third area was the formation of finer and denser

martensite plates closer to the graphite flakes compared with those formed at a further distance. In the fourth layer

there is a mixture of martensitic and pearlitic matrix while the matrix of fifth layer has no change of microstructure.

In this study the effect of graphite flakes present in a pearlitic grey cast iron on the microstructure of melted,

A. Rezvanifar, M. Zandrahimi,
Volume 7, Issue 1 (3-2010)
Abstract

Abstract:

powerful method for the characterization of microstructures of crystalline materials in terms of crystallite size and

dislocation structures. In this paper the effect of the sliding on the microstructure of A356 in the as-cast and heat

treated conditions are studied, The X-ray phase analysis shows that with increasing applied load, the dislocation

density is increased, whereas the crystallite size is decreased. It was found that heat treatment raised dislocation

density during wear. The screw or edge character of dislocations in worn specimens were determined by analyzing the

dislocation contrast factors, it was demonstrated that the character of the prevailing dislocations in high loads is

nearly pure screw.

Diffraction peak profile analysis has recently been developed to such an extent that it can be applied as a

M. Zandrahimi, A. Rezvanifar,
Volume 9, Issue 1 (3-2012)
Abstract

Abstract: Cold working performed before an aging treatment has a significant effect on size and amount of precipitate produced. This could be caused by the increase in defect density, such as vacancies and dislocations. In this research, the Al-Cu-Si alloy was solution-treated, wear-tested and then artificially aged for a period of 1–5 h. Changes in the amount of precipitate, in the lattice parameter of the matrix, and in the precipitates are measured by X-ray diffraction and then calculated.It was observed that performing a wear test before the aging treatment was done significantly increased the amount of precipitate, while wear rate decreased.
A. Salimi, M. Zadshakoyan, A. Ozdemir, E. Seidi,
Volume 9, Issue 2 (6-2012)
Abstract

In automation flexible manufacturing systems, tool wear detection during the cutting process is one of the most important considerations. This study presents an intelligent system for online tool condition monitoring in drilling process .In this paper, analytical and empirical models have been used to predict the thrust and cutting forces on the lip and chisel edges of a new drill. Also an empirical model is used to estimate tool wear rate and force values on the edges of the worn drill. By using of the block diagram of machine tool drives, the changes in the feed and spindle motor currents are simulated, as wear rate increases. To predict tool wear rate in drill, Fuzzy logic capabilities have been used to develop intelligent system. The simulated results presented in MATLAB software show the effectiveness of the proposed system for on-line drill wear monitoring.
M. Alipour, S. Mirjavadi, M. K. Besharati Givi, H. Razmi, M. Emamy, J. Rassizadehghani,
Volume 9, Issue 4 (12-2012)
Abstract

In this study the effect of Al–5Ti–1B grain refiner on the structural characteristics and wear properties of Al–12Zn–3Mg–2.5Cu alloy was investigated. The optimum amount for Ti containing grain refiners was selected as 2 wt.%. T6 heat treatment, (i.e. heating at 460 °C for 1 h before water quenching to room temperature and then aging at 120 °C for 24 h) was applied for all specimens before wear testing. Dry sliding wear resistant of the alloy was performed under normal atmospheric conditions. The experimental results showed that the T6 heat treatment considerably improved the resistance of Al–12Zn–3Mg–2.5Cu alloy to dry sliding wear.
Z. Shahri, S.r. Allahkaram,
Volume 9, Issue 4 (12-2012)
Abstract

Metal matrix composite coatings reinforced with nano-particles have attracted scientific and technological interest due to the enhanced properties exhibited by these coatings. Cobalt/hexagonal boron nitride nano-composite coatings were prepared by means of the pulse current electroplating from a chloride electrolyte on copper substrates and a comparison was made with the pure cobalt in terms of structure and tribological properties. Effects of particles concentration (5-20 gL-1) and current density (50-200 mA cm-2) on the characterization of electroplated coatings were investigated via X-ray diffraction analysis, energy dispersive spectroscopy and Vickers micro-hardness. Moreover, the tribological behavior was studied using pin-on-disc method. The results showed that cobalt/hexagonal boron nitride nano-composite coatings have higher hardness, wear resistance and lower friction coefficient than pure cobalt and the plating parameters strongly affect the coating’s properties
S. R. Allahkaram, R. Faezi Alivand, M. S. Bakhsh,
Volume 10, Issue 1 (3-2013)
Abstract

Abstract:Electroless Nickel-phosphorus (EN) coatings provide high performance in various industrial fields due to their unique properties such as excellent corrosion and wear resistance. This paper aims to study the effect of ZnO nano-particles addition on corrosion behavior of EN coatings. Various amounts of ZnO nano-particles with average diameter of 50 nm were added to hypophosphite reduced EN bath to deposit composite coatings. Microstructural investigations were carried out via scanning electron microscopy (SEM). Chemical composition of the coatings was investigated via energy dispersive spectroscopy (EDS). Electrochemical impedance spectroscopy (EIS) and polarization tests were used to study the corrosion properties of the coatings in a 3.5 wt.% NaCl solution. SEM investigations showed that the coating deposited from the bath containing 2 g/L of ZnO nano-particles had the most amount of nano-particles incorporated in the coating. EDS results revealed that incorporation of ZnO nano-particles in the composite coating resulted in a decrease in phosphorous content of the coating. Corrosion tests showed that corrosion resistance of the electroless Ni-P/nanoZnO composite coatings in 3.5 wt.% NaCl solution had an improvement in comparison to electroless Ni-P base coating
H. Arabi, S. Rastegari, V. Ramezani, Z. Valefi,
Volume 10, Issue 2 (6-2013)
Abstract

The objectives of this research were to find an economical way of reducing porosities in the microstructure of coatings deposited by flame spraying technique on CK45 steel and also trying to increase their cohesive strength to the substrate, so that the overall wear properties of this type of coating can be improved. So several specimens from this steel coated with NiCrBSi powder under specific conditions were subjected to various furnace heat treatment at 1000, 1025, 1050, 1075 and 1100 °C, each for periods of 5, 10 and 15 minute before cooling them in air. Tribological properties of treated coatings were evaluated by pin on disc method. The results show the highest wear resistance and microhardness values observed in one of the sample was due to lower amount of porosity and higher amount of very fine Cr2Ni3B6 particles precipitated homogeneously throughout its microstructure during specific heat treatment.
K. Taherkhani, F. Mahboubi,
Volume 10, Issue 2 (6-2013)
Abstract

Nitriding is a surface treatment technique used to introduce nitrogen into metallic materials to improve their surface hardness, mechanical properties, wear resistance and corrosion resistance. In this research, the effects of plasma nitriding parameters including frequency and duty cycle were investigated on samples with different grooves dimensions. Steel blocks prepared from DIN1.2344 hot working steel were plasma nitride at 500 °C under the atmosphere contents of %75H2-%25N2, the duty cycles of 40%, 60%, 80%, and the frequencies of 8, 10 kHz for 5 hours. Then characteristics and micro hardness's of the nitrided samples were investigated using SEM, XRD, and Vickers Micro Hardness method. The results of the experiments indicated that with increasing frequency, the duty cycle, and the thickness of the grooves, the roughness of the surfaces increased. With an increase in duty cycle from 40% to 80%, the hardness of the surface rose and the thickness of the compound layer built up. Hollow cathode effect occurred in the samples with small grooves and high duty cycle in plasma nitriding. This will result in over heating of the sample which leads to a decrease in the slope of hardness values from the surface to the core of the sample and also a decrease in the diffused depth of nitrogen. The compound layer of the treated samples consisted of @ : Fe4N and : Fe2-3N phases and the proportion of the A to @ increased with the decrease in the duty cycle. Increasing the frequency did not affect the proportion of phases and micro hardness of the samples.
F. Mahzoon, S. A. Behgozin, N. Afsar Kazerooni, M. E. Bahrololoom,
Volume 10, Issue 3 (9-2013)
Abstract

The wear mechanism of plasma electrolytic nitrocarburised (PEN/C) 316L stainless steel samples was studied after a pin on disc wear test. The surface morphology of samples after application of PEN/C process was studied using scanning electron microscope technique. The sliding tracks resulting from the wear tests on the treated specimens indicated no signs of plastic deformation and adhesive wear, but the slider wear particles were trapped in the micro-craters of the counterface. The results showed that this mechanism may further improve the tribological performance of the system by increasing the wear resistance and lowering friction. PEN/C treated surfaces are therefore believed to have the potential to limit metal-to-metal wear mechanisms on a microscale, if contact pressures are sufficiently low
Z. Shahri, S. R. Allahkaram,
Volume 10, Issue 4 (12-2013)
Abstract

Metal matrix nano composite coatings possess enhanced properties such as corrosion and wear resistance. This paper aims to study the corrosion behavior of pure Co and Co-BN nano composite coatings deposited with different particles concentration (5-20 g L-1) on copper substrates using electroplating technique. Morphology and elemental compositions of the coatings were investigated by means of scanning electron microscope (SEM) equipped with an energy dispersive spectroscopy (EDS). The corrosion behavior was analyzed in a 3.5 wt% NaCl via polarization and impedance techniques. The results obtained in this study indicate that the co-deposition of BN nano particles improved corrosion resistance of electrodeposited cobalt coatings.
A. Azizi, S. Z. Shafaei, M. Noaparast, M. Karamoozian,
Volume 10, Issue 4 (12-2013)
Abstract

This paper was aimed to address the modeling and optimization of factors affecting the corrosive wear of low alloy and high carbon chromium steel balls. Response surface methodology, central composite design (CCD) was employed to assess the main and interactive effects of the parameters and also to model and minimize the corrosive wear of the steels. The second-order polynomial regression model was proposed for relationship between the corrosion rates and relevant investigated parameters. Model fitted to results indicated that the linear effects of all of factors, interactive effect of pH and grinding time and the quadratic effects of pH and balls charge weight, were statistically significant in corrosive wear of low alloy steel balls. The significant parameters in the corrosive wear of high carbon chromium steel balls were the linear effects of all factors, the interactions effect of solid concentration, mill speed, mill throughout, grinding time, and the quadratic effects of pH and solid content. Also, the results showed that within the range of parameters studied, the corrosion rate of 78.38 and 40.76 could be obtained for low alloy and high carbon chromium steel balls, respectively.
M. Kadkhodaee, H. Daneshmanesh, B. Hashemi, J. Moradgholi,
Volume 11, Issue 1 (3-2014)
Abstract

Accumulative roll-bonding process (ARB) is an important severe plastic deformation technique for production of the ultrafine grained, nanostructured and nanocomposite materials in the form of plates and sheets. In the present work, this process used for manufacturing Al/SiO 2 nanocomposites by using Aluminum 1050 alloy sheets and nano sized SiO 2 particles, at ambient temperature. After 8 cycles of ARB process, the tribological properties and wear resistance of produced nanocomposites were investigated. The wear tests by abrasion were performed in a pinon-disc tribometer. Results show that by increasing ARB cycles and the amount of nano powders, the friction coefficient of produced nanocomposites decreases.

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