Nejat SARI - Academia.edu (original) (raw)
Papers by Nejat SARI
Polymer Composites, Oct 1, 2009
The influence of erodent particle types on solid particle erosion of randomly oriented short glas... more The influence of erodent particle types on solid particle erosion of randomly oriented short glass fiber and mineral particle reinforced polyphenylene sulphide (PPS) was investigated. The solid particle erosion studies were carried out using low speed solid particle erosion test rig with 150 to 212-lm brown fused aluminum oxide (Al 2 O 3), 150 to 200-lm silica sand and 150 to 250-lm glass bead. Glass bead eroding particles appear spherical in shape whereas aluminum oxide and silica sand eroding particles have sharp and angular edges. The erosion tests were conducted at six different contact angles of 15, 30, 45, 60, 75, and 908, respectively. The results showed a strong dependence of the eroding particle types on the erosive wear behavior of PPS composite. The peak erosion rate occurred at 458 contact angle for silica sand eroding particles while the peak erosion rate occurred at 308 contact angle for aluminum oxide and glass bead particles. The morphologies of eroded surfaces were characterized by the scanning electron microscopy. In case of aluminum oxide and silica sand, the erosive wear mechanism occurs firstly by the erosion of matrix, followed by the fracture of unsupported fibers and their detachment; however, the erosive wear mechanism occurs different for glass bead particles.
European journal of technique, Jan 3, 2022
Materials & Design, 2006
In the present technology, machine parts which work at the industry area such as agriculture, min... more In the present technology, machine parts which work at the industry area such as agriculture, mining and cement are subjected to wear. The wear resistance of these parts is improved by conventional heat treatments or surface heat treatments, which only improved the property surface and sub-surface of materials.In this study, samples of AISI 1050 steel are subjected to induction hardening and thermochemical treatments such as boronising, nitriding and thermal spraying which involves flame spraying, flame spraying plus melting, high velocity oxyfuel (HVOF) plus melting apart from the conventional heat treatment, which is oil quenching.At the end of wear tests, it is observed that the amount of wear in base metal decreased with the oil quenching but on the contrary to that the wear resistance was not improved with induction hardening and the other thermochemical surface treatments.However, the amount of wear in base metal was significantly decreased with thermal spraying methods. Even the additionally applied remelting treatment after spraying reduced to more smaller amounts. So, the applied remelting treatment after spraying plays much more important role in reducing wear. At wear surfaces of thermal spraying samples, the regional surface damages with slight traces of abrasive wear are seen.
Materials & Design, 2007
In this study, erosive wear behaviour of unidirectional carbon fibre reinforced polyetherimide (P... more In this study, erosive wear behaviour of unidirectional carbon fibre reinforced polyetherimide (PEI) matrix composites was investigated with regards to the effects of contact speed, contact angles of particles and erosion period under low particle speed. Unidirectional carbon fibre reinforced PEI composites show semi-ductile behaviour under low speed erosive studies. Highest wear rates were investigated at 45°for 1.96 m/s and 50-55°for 2.88 m/s. Higher particle speed was found to be given higher wear rates at higher peak contact angles compared to lower particle speed. Erosive wear rates and the surface roughness have a close relationship with the contact angle of the erodent and speed. Higher particle speed resulted in rougher surface as a result of severe fibre breakage and matrix erosion.
Polymer Composites, 2009
The influence of erodent particle types on solid particle erosion of randomly oriented short glas... more The influence of erodent particle types on solid particle erosion of randomly oriented short glass fiber and mineral particle reinforced polyphenylene sulphide (PPS) was investigated. The solid particle erosion studies were carried out using low speed solid particle erosion test rig with 150 to 212-lm brown fused aluminum oxide (Al 2 O 3), 150 to 200-lm silica sand and 150 to 250-lm glass bead. Glass bead eroding particles appear spherical in shape whereas aluminum oxide and silica sand eroding particles have sharp and angular edges. The erosion tests were conducted at six different contact angles of 15, 30, 45, 60, 75, and 908, respectively. The results showed a strong dependence of the eroding particle types on the erosive wear behavior of PPS composite. The peak erosion rate occurred at 458 contact angle for silica sand eroding particles while the peak erosion rate occurred at 308 contact angle for aluminum oxide and glass bead particles. The morphologies of eroded surfaces were characterized by the scanning electron microscopy. In case of aluminum oxide and silica sand, the erosive wear mechanism occurs firstly by the erosion of matrix, followed by the fracture of unsupported fibers and their detachment; however, the erosive wear mechanism occurs different for glass bead particles.
Polymer Composites, 2009
The effect of erodent particle size on solid particle erosion of randomly oriented short glass fi... more The effect of erodent particle size on solid particle erosion of randomly oriented short glass fiber and mineral particle reinforced polyphenylene sulfide (PPS) was investigated. To examine the effect of erodent size on the erosion resistance of the PPS composite, aluminum oxide particles at three different sizes, namely, 300–425 μm, 150–212 μm, and 45–75 μm, were used. The erosion tests were performed at six different contact angles of 15°, 30°, 45°, 60°, 75°, and 90°, respectively. The results showed a strong relationship between the erodent particle size and erosion rates of PPS composite. Maximum erosion rate for the erodent particles with sizes of 45–75 μm and 150–212 μm occurred at contact angle of 30°, on the other hand maximum erosion rate for particles having 300–425 μm size occurred between 45° and 60°. The morphologies of eroded surfaces were characterized by the scanning electron microscopy (SEM). Possible erosion mechanisms were discussed. POLYM. COMPOS., 2010. © 2009 S...
Journal of Thermoplastic Composite Materials, 2010
In this study, solid particle erosive wear behavior of randomly oriented short glass fiber and ca... more In this study, solid particle erosive wear behavior of randomly oriented short glass fiber and carbon fiber-reinforced polyetheretherketone (PEEK) composites was investigated. The solid particle erosion experiments were carried out at six different contact angles (15—90°) and at low particle speed using brown fused aluminum oxide (Al2O3) particles (500—710 µm) as an erodent. The PEEK composites showed semi-ductile erosion behavior, with a maximum wear amount at a contact angle of 45°. The fiber type and the contact angle had a significant influence on erosion behavior. Glass fiber-reinforced PEEK composites showed better erosive wear resistance than carbon fibre-reinforced composites. Scanning electron microscopy studies were conducted to understand the wear mechanisms involved during the erosive wear.
Acta Physica Polonica A, 2014
The eect of low temperature plasma nitriding on wear resistance of Ti6Al4V alloy were investigate... more The eect of low temperature plasma nitriding on wear resistance of Ti6Al4V alloy were investigated. There have been several studies to investigate the low temperature plasma nitriding on Ti6Al4V alloy. Plasma nitriding processes under gas mixture of N2/H2 = 3 were performed at temperature 535 • C for duration of 4, 8 and 12 h. Adhesive wear tests were carried out by using a tribometer in block-on-ring conguration (ASTM G77), in sliding conditions, without lubricants and in air. Surface hardness of the plasma nitrided samples were measured by a Vickers hardness tester machine. Scanning electron microscopy studies were conducted to understand the wear mechanisms involved during the adhesive wear. Wear rate was calculated using weight loss per unit sliding distance. It was found that the wear resistance and surface hardness of the alloy improved considerably after plasma nitriding process. The wear resistance of the plasma nitrided samples were higher than of the unnitrided samples. Extension of nitriding times from 4 h to 12 h in the Ti6Al4V alloy improved remerkably the wear resistance and surface hardness.
Surface and Coatings Technology, 2008
In wire drawing process, wear of rolls must be considered because of wear that influences the eco... more In wire drawing process, wear of rolls must be considered because of wear that influences the economics of the forming process. In this study, a nickel based matrix reinforced with WC was deposited by low cost powder welding method on low carbon steel substrates in order to determine the wear resistance of wire drawing rolls. Powder welding method includes, contrary to plasma and high velocity oxyfuel (HVOF) spraying methods, the advantages such as the single operation of powder application-fusion, simplicity, cheapness, and the ease of application. Blends of NiCrBSi and WC powders were prepared in weight proportions of WC of 40%, 45%, 50%, 55%, and 60%, respectively. Wear performance of these coatings was investigated by the dry sliding wear experiments. The wear resistance of the metal matrix composite coatings is dependent on the amount of WC. From 40% to 60%, the increase of WC is very effective on the wear resistance. The coatings with 55% and 60% of WC were worn less than the other coatings. From 55% to 60%, further increase of WC was found not to be effective for the best wear resistance. The microscopic studies of WC particles and Ni-based matrix were characterized by the scanning electron microscopy (SEM). The SEM analysis on the worn surface of coated samples shows that the matrix is considerably worn while WC particles are not considerably worn at the beginning of the wear testing. Additionally, WC particles effectively provide protection for achievement of the wear resistance at advanced periods of the wear testing.
Polymer Composites, Oct 1, 2009
The influence of erodent particle types on solid particle erosion of randomly oriented short glas... more The influence of erodent particle types on solid particle erosion of randomly oriented short glass fiber and mineral particle reinforced polyphenylene sulphide (PPS) was investigated. The solid particle erosion studies were carried out using low speed solid particle erosion test rig with 150 to 212-lm brown fused aluminum oxide (Al 2 O 3), 150 to 200-lm silica sand and 150 to 250-lm glass bead. Glass bead eroding particles appear spherical in shape whereas aluminum oxide and silica sand eroding particles have sharp and angular edges. The erosion tests were conducted at six different contact angles of 15, 30, 45, 60, 75, and 908, respectively. The results showed a strong dependence of the eroding particle types on the erosive wear behavior of PPS composite. The peak erosion rate occurred at 458 contact angle for silica sand eroding particles while the peak erosion rate occurred at 308 contact angle for aluminum oxide and glass bead particles. The morphologies of eroded surfaces were characterized by the scanning electron microscopy. In case of aluminum oxide and silica sand, the erosive wear mechanism occurs firstly by the erosion of matrix, followed by the fracture of unsupported fibers and their detachment; however, the erosive wear mechanism occurs different for glass bead particles.
European journal of technique, Jan 3, 2022
Materials & Design, 2006
In the present technology, machine parts which work at the industry area such as agriculture, min... more In the present technology, machine parts which work at the industry area such as agriculture, mining and cement are subjected to wear. The wear resistance of these parts is improved by conventional heat treatments or surface heat treatments, which only improved the property surface and sub-surface of materials.In this study, samples of AISI 1050 steel are subjected to induction hardening and thermochemical treatments such as boronising, nitriding and thermal spraying which involves flame spraying, flame spraying plus melting, high velocity oxyfuel (HVOF) plus melting apart from the conventional heat treatment, which is oil quenching.At the end of wear tests, it is observed that the amount of wear in base metal decreased with the oil quenching but on the contrary to that the wear resistance was not improved with induction hardening and the other thermochemical surface treatments.However, the amount of wear in base metal was significantly decreased with thermal spraying methods. Even the additionally applied remelting treatment after spraying reduced to more smaller amounts. So, the applied remelting treatment after spraying plays much more important role in reducing wear. At wear surfaces of thermal spraying samples, the regional surface damages with slight traces of abrasive wear are seen.
Materials & Design, 2007
In this study, erosive wear behaviour of unidirectional carbon fibre reinforced polyetherimide (P... more In this study, erosive wear behaviour of unidirectional carbon fibre reinforced polyetherimide (PEI) matrix composites was investigated with regards to the effects of contact speed, contact angles of particles and erosion period under low particle speed. Unidirectional carbon fibre reinforced PEI composites show semi-ductile behaviour under low speed erosive studies. Highest wear rates were investigated at 45°for 1.96 m/s and 50-55°for 2.88 m/s. Higher particle speed was found to be given higher wear rates at higher peak contact angles compared to lower particle speed. Erosive wear rates and the surface roughness have a close relationship with the contact angle of the erodent and speed. Higher particle speed resulted in rougher surface as a result of severe fibre breakage and matrix erosion.
Polymer Composites, 2009
The influence of erodent particle types on solid particle erosion of randomly oriented short glas... more The influence of erodent particle types on solid particle erosion of randomly oriented short glass fiber and mineral particle reinforced polyphenylene sulphide (PPS) was investigated. The solid particle erosion studies were carried out using low speed solid particle erosion test rig with 150 to 212-lm brown fused aluminum oxide (Al 2 O 3), 150 to 200-lm silica sand and 150 to 250-lm glass bead. Glass bead eroding particles appear spherical in shape whereas aluminum oxide and silica sand eroding particles have sharp and angular edges. The erosion tests were conducted at six different contact angles of 15, 30, 45, 60, 75, and 908, respectively. The results showed a strong dependence of the eroding particle types on the erosive wear behavior of PPS composite. The peak erosion rate occurred at 458 contact angle for silica sand eroding particles while the peak erosion rate occurred at 308 contact angle for aluminum oxide and glass bead particles. The morphologies of eroded surfaces were characterized by the scanning electron microscopy. In case of aluminum oxide and silica sand, the erosive wear mechanism occurs firstly by the erosion of matrix, followed by the fracture of unsupported fibers and their detachment; however, the erosive wear mechanism occurs different for glass bead particles.
Polymer Composites, 2009
The effect of erodent particle size on solid particle erosion of randomly oriented short glass fi... more The effect of erodent particle size on solid particle erosion of randomly oriented short glass fiber and mineral particle reinforced polyphenylene sulfide (PPS) was investigated. To examine the effect of erodent size on the erosion resistance of the PPS composite, aluminum oxide particles at three different sizes, namely, 300–425 μm, 150–212 μm, and 45–75 μm, were used. The erosion tests were performed at six different contact angles of 15°, 30°, 45°, 60°, 75°, and 90°, respectively. The results showed a strong relationship between the erodent particle size and erosion rates of PPS composite. Maximum erosion rate for the erodent particles with sizes of 45–75 μm and 150–212 μm occurred at contact angle of 30°, on the other hand maximum erosion rate for particles having 300–425 μm size occurred between 45° and 60°. The morphologies of eroded surfaces were characterized by the scanning electron microscopy (SEM). Possible erosion mechanisms were discussed. POLYM. COMPOS., 2010. © 2009 S...
Journal of Thermoplastic Composite Materials, 2010
In this study, solid particle erosive wear behavior of randomly oriented short glass fiber and ca... more In this study, solid particle erosive wear behavior of randomly oriented short glass fiber and carbon fiber-reinforced polyetheretherketone (PEEK) composites was investigated. The solid particle erosion experiments were carried out at six different contact angles (15—90°) and at low particle speed using brown fused aluminum oxide (Al2O3) particles (500—710 µm) as an erodent. The PEEK composites showed semi-ductile erosion behavior, with a maximum wear amount at a contact angle of 45°. The fiber type and the contact angle had a significant influence on erosion behavior. Glass fiber-reinforced PEEK composites showed better erosive wear resistance than carbon fibre-reinforced composites. Scanning electron microscopy studies were conducted to understand the wear mechanisms involved during the erosive wear.
Acta Physica Polonica A, 2014
The eect of low temperature plasma nitriding on wear resistance of Ti6Al4V alloy were investigate... more The eect of low temperature plasma nitriding on wear resistance of Ti6Al4V alloy were investigated. There have been several studies to investigate the low temperature plasma nitriding on Ti6Al4V alloy. Plasma nitriding processes under gas mixture of N2/H2 = 3 were performed at temperature 535 • C for duration of 4, 8 and 12 h. Adhesive wear tests were carried out by using a tribometer in block-on-ring conguration (ASTM G77), in sliding conditions, without lubricants and in air. Surface hardness of the plasma nitrided samples were measured by a Vickers hardness tester machine. Scanning electron microscopy studies were conducted to understand the wear mechanisms involved during the adhesive wear. Wear rate was calculated using weight loss per unit sliding distance. It was found that the wear resistance and surface hardness of the alloy improved considerably after plasma nitriding process. The wear resistance of the plasma nitrided samples were higher than of the unnitrided samples. Extension of nitriding times from 4 h to 12 h in the Ti6Al4V alloy improved remerkably the wear resistance and surface hardness.
Surface and Coatings Technology, 2008
In wire drawing process, wear of rolls must be considered because of wear that influences the eco... more In wire drawing process, wear of rolls must be considered because of wear that influences the economics of the forming process. In this study, a nickel based matrix reinforced with WC was deposited by low cost powder welding method on low carbon steel substrates in order to determine the wear resistance of wire drawing rolls. Powder welding method includes, contrary to plasma and high velocity oxyfuel (HVOF) spraying methods, the advantages such as the single operation of powder application-fusion, simplicity, cheapness, and the ease of application. Blends of NiCrBSi and WC powders were prepared in weight proportions of WC of 40%, 45%, 50%, 55%, and 60%, respectively. Wear performance of these coatings was investigated by the dry sliding wear experiments. The wear resistance of the metal matrix composite coatings is dependent on the amount of WC. From 40% to 60%, the increase of WC is very effective on the wear resistance. The coatings with 55% and 60% of WC were worn less than the other coatings. From 55% to 60%, further increase of WC was found not to be effective for the best wear resistance. The microscopic studies of WC particles and Ni-based matrix were characterized by the scanning electron microscopy (SEM). The SEM analysis on the worn surface of coated samples shows that the matrix is considerably worn while WC particles are not considerably worn at the beginning of the wear testing. Additionally, WC particles effectively provide protection for achievement of the wear resistance at advanced periods of the wear testing.