The Experts below are selected from a list of 2448 Experts worldwide ranked by ideXlab platform
John R. Tyrer - One of the best experts on this subject based on the ideXlab platform.
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Nd:YAG laser drilling of 8.3 mm thick partially stabilized tetragonal zirconia-control of Recast Layer microcracking using localized heating techniques
Journal of Laser Applications, 1999Co-Authors: A. J. Murray, John R. TyrerAbstract:The machining of ceramic components using conventional techniques is slow and expensive due to low yields. High power lasers are capable of machining these materials at far greater speeds. However, the performance of ceramic substrates is dependent on the quality of the processed region, with specific reference to the level of microcracking. The propagation of microcracks into the bulk substrate inevitably leads to component failure. Generation of Recast Layer microcracking is the Achilles heel of laser processing of ceramics. The fundamental process of laser radiation interaction with ceramic substrates generates a severe thermal gradient between the Recast Layer and bulk substrate. This in turn leads to the stresses which cause microcracks to form. Techniques for the reduction of this thermal shear have been investigated. Optimization of Nd:YAG laser drilling enabled repeatable and high quality processing to be undertaken. However, adaptation of these conventional techniques was required to reduce the level of Recast Layer microcracking. A method for the numerical characterization of microcracking was developed for this work and was based upon SEM image processing. The use of a high temperature furnace to heat substrates before and after laser processing reduced the level of Recast Layer microcracking by half, when compared to the ambient temperature process. However, sufficient microcracking was present to cause substrate failure. An unconventional plasma heating technique was developed and applied for the reduction of this cracking. For laser drilling at 1300 °C, the addition of localized plasma heating gave a further 14% mean reduction in Recast Layer microcracking. This advanced drilling technique also produced a 12% increase in mean hole diameter when compared to the furnace heating method.The machining of ceramic components using conventional techniques is slow and expensive due to low yields. High power lasers are capable of machining these materials at far greater speeds. However, the performance of ceramic substrates is dependent on the quality of the processed region, with specific reference to the level of microcracking. The propagation of microcracks into the bulk substrate inevitably leads to component failure. Generation of Recast Layer microcracking is the Achilles heel of laser processing of ceramics. The fundamental process of laser radiation interaction with ceramic substrates generates a severe thermal gradient between the Recast Layer and bulk substrate. This in turn leads to the stresses which cause microcracks to form. Techniques for the reduction of this thermal shear have been investigated. Optimization of Nd:YAG laser drilling enabled repeatable and high quality processing to be undertaken. However, adaptation of these conventional techniques was required to reduce the l...
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nd yag laser drilling of 8 3 mm thick partially stabilized tetragonal zirconia control of Recast Layer microcracking using localized heating techniques
Journal of Laser Applications, 1999Co-Authors: A. J. Murray, John R. TyrerAbstract:The machining of ceramic components using conventional techniques is slow and expensive due to low yields. High power lasers are capable of machining these materials at far greater speeds. However, the performance of ceramic substrates is dependent on the quality of the processed region, with specific reference to the level of microcracking. The propagation of microcracks into the bulk substrate inevitably leads to component failure. Generation of Recast Layer microcracking is the Achilles heel of laser processing of ceramics. The fundamental process of laser radiation interaction with ceramic substrates generates a severe thermal gradient between the Recast Layer and bulk substrate. This in turn leads to the stresses which cause microcracks to form. Techniques for the reduction of this thermal shear have been investigated. Optimization of Nd:YAG laser drilling enabled repeatable and high quality processing to be undertaken. However, adaptation of these conventional techniques was required to reduce the l...
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Nd:YAG laser cutting and drilling of PSTZ—Influence of substrate heating temperature on Recast Layer microcracking
Journal of Laser Applications, 1999Co-Authors: A. J. Murray, John R. TyrerAbstract:The machining of ceramic components using conventional techniques is slow and expensive due to low yields. High power lasers are capable of machining these materials at far greater speeds. Recast Layer microcracking is the Achilles heel of laser processing of ceramics. Techniques for the reduction of the thermal shear caused by laser beam interaction have been investigated. A method for the numerical characterization of microcracking was developed for this work and was based upon scanning electron microscopy image processing. Optimization of the pulsed Nd:YAG laser drilling and cutting cycles enabled repeatable, high quality processing to be undertaken. Heating of the partially stabilized tetragonal zirconia (PSTZ) substrates to high temperatures before and after laser processing was found to reduce the thermal gradients that cause microcracking. Holes with a mean diameter of 679 μm were percussion drilled through the 8.3 mm thick substrates in 0.75 s, and had limited tapering (
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nd yag laser cutting and drilling of pstz influence of substrate heating temperature on Recast Layer microcracking
Journal of Laser Applications, 1999Co-Authors: A. J. Murray, John R. TyrerAbstract:The machining of ceramic components using conventional techniques is slow and expensive due to low yields. High power lasers are capable of machining these materials at far greater speeds. Recast Layer microcracking is the Achilles heel of laser processing of ceramics. Techniques for the reduction of the thermal shear caused by laser beam interaction have been investigated. A method for the numerical characterization of microcracking was developed for this work and was based upon scanning electron microscopy image processing. Optimization of the pulsed Nd:YAG laser drilling and cutting cycles enabled repeatable, high quality processing to be undertaken. Heating of the partially stabilized tetragonal zirconia (PSTZ) substrates to high temperatures before and after laser processing was found to reduce the thermal gradients that cause microcracking. Holes with a mean diameter of 679 μm were percussion drilled through the 8.3 mm thick substrates in 0.75 s, and had limited tapering (<150 μm). Single pass, full...
J. S. Huang - One of the best experts on this subject based on the ideXlab platform.
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Electrical discharge machining of a NiAlFe ternary shape memory alloy
Journal of Alloys and Compounds, 2008Co-Authors: Shyh-leh Chen, M.-h. Lin, S. F. Hsieh, H. C. Lin, J. S. HuangAbstract:The electro-discharge machining (EDM) characteristics of a NiAlFe ternary shape memory alloy (SMA) have been investigated in this study. Experimental results reveal that the material removal rates (MRRs) of Ni60Al24.5Fe15.5 and Ti35.5Ni49.5Zr15 alloys in the EDM process exhibit a reverse relationship to the product of the alloy's melting temperature and thermal conductivity. In addition, a precise EDM machining of NiAlFe SMA can be obtained by setting the machine parameters at low pulse energy. The surface roughness (Ra) of the EDMed NiAlFe SMA is found to follow the empirical equation of Ra = λ(IP × τP)β. Having a less TΘ × KT value, Ni60Al24.5Fe15.5 alloy has a larger Ra value than that of Ti35.5Ni49.5Zr15 alloy after electro-discharge machining. The Recast Layer consists of the oxides Fe2O3, Al2O3, NiO and the deposition particles of the consumed Cu electrode and dissolved dielectric medium. The hardening effect near the outer surface for EDMed NiAlFe alloy originates from the Recast Layer. The thickness of the Recast Layer varies with the pulse duration and exhibits a minimum value at the maximal MRR. © 2007 Elsevier B.V. All rights reserved.
Shyh-leh Chen - One of the best experts on this subject based on the ideXlab platform.
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EDM surface characteristics and shape recovery ability of Ti35.5Ni48.5Zr16 and Ni60Al24.5Fe15.5 ternary shape memory alloys
Journal of Alloys and Compounds, 2013Co-Authors: S. F. Hsieh, Shyh-leh Chen, Albert Wen-jeng Hsue, Keng Liang OuAbstract:Abstract Electro-discharge craters and Recast materials are observed in the electro-discharge machining (EDM) surface of Ti 35.5 Ni 48.5 Zr 16 and Ni 60 Al 24.5 Fe 15.5 alloys. The Recast Layer is composed of TiO, NiO, ZrO 2 , Fe 2 O 3 , Al 2 O 3. The hardening effect near the outer surface for EDMed TiNiZr alloy originates from the surface oxides of the Recast Layer. The thickness of the Recast Layer increases upon growing pulse energy. The EDMed Ti 35.5 Ni 48.5 Zr 16 alloy still exhibits a good shape recovery, but the shape recovery is slightly reduced due to the depression of the Recast Layer. The material removal rate (MRR) of Ti 35.5 Ni 48.5 Zr 16 alloy is less than that of Ni 60 Al 24.5 Fe 15.5 alloy because of the larger θ × k α value. A high discharge energy should have a larger and deeper craters, and a rougher surface. The surface roughness of the EDMed TiNiZr and NiAlFe SMAs is found to obey the empirical equation of Ra = C ( I P × τ P ) β . Having a larger θ × K α value, Ti 35.5 Ni 48.5 Zr 16 alloy has a lower Ra value than that of Ni 60 Al 24.5 Fe 15.5 alloy after electro-discharge machining.
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Electrical discharge machining of a NiAlFe ternary shape memory alloy
Journal of Alloys and Compounds, 2008Co-Authors: Shyh-leh Chen, M.-h. Lin, S. F. Hsieh, H. C. Lin, J. S. HuangAbstract:The electro-discharge machining (EDM) characteristics of a NiAlFe ternary shape memory alloy (SMA) have been investigated in this study. Experimental results reveal that the material removal rates (MRRs) of Ni60Al24.5Fe15.5 and Ti35.5Ni49.5Zr15 alloys in the EDM process exhibit a reverse relationship to the product of the alloy's melting temperature and thermal conductivity. In addition, a precise EDM machining of NiAlFe SMA can be obtained by setting the machine parameters at low pulse energy. The surface roughness (Ra) of the EDMed NiAlFe SMA is found to follow the empirical equation of Ra = λ(IP × τP)β. Having a less TΘ × KT value, Ni60Al24.5Fe15.5 alloy has a larger Ra value than that of Ti35.5Ni49.5Zr15 alloy after electro-discharge machining. The Recast Layer consists of the oxides Fe2O3, Al2O3, NiO and the deposition particles of the consumed Cu electrode and dissolved dielectric medium. The hardening effect near the outer surface for EDMed NiAlFe alloy originates from the Recast Layer. The thickness of the Recast Layer varies with the pulse duration and exhibits a minimum value at the maximal MRR. © 2007 Elsevier B.V. All rights reserved.
A. J. Murray - One of the best experts on this subject based on the ideXlab platform.
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Nd:YAG laser drilling of 8.3 mm thick partially stabilized tetragonal zirconia-control of Recast Layer microcracking using localized heating techniques
Journal of Laser Applications, 1999Co-Authors: A. J. Murray, John R. TyrerAbstract:The machining of ceramic components using conventional techniques is slow and expensive due to low yields. High power lasers are capable of machining these materials at far greater speeds. However, the performance of ceramic substrates is dependent on the quality of the processed region, with specific reference to the level of microcracking. The propagation of microcracks into the bulk substrate inevitably leads to component failure. Generation of Recast Layer microcracking is the Achilles heel of laser processing of ceramics. The fundamental process of laser radiation interaction with ceramic substrates generates a severe thermal gradient between the Recast Layer and bulk substrate. This in turn leads to the stresses which cause microcracks to form. Techniques for the reduction of this thermal shear have been investigated. Optimization of Nd:YAG laser drilling enabled repeatable and high quality processing to be undertaken. However, adaptation of these conventional techniques was required to reduce the level of Recast Layer microcracking. A method for the numerical characterization of microcracking was developed for this work and was based upon SEM image processing. The use of a high temperature furnace to heat substrates before and after laser processing reduced the level of Recast Layer microcracking by half, when compared to the ambient temperature process. However, sufficient microcracking was present to cause substrate failure. An unconventional plasma heating technique was developed and applied for the reduction of this cracking. For laser drilling at 1300 °C, the addition of localized plasma heating gave a further 14% mean reduction in Recast Layer microcracking. This advanced drilling technique also produced a 12% increase in mean hole diameter when compared to the furnace heating method.The machining of ceramic components using conventional techniques is slow and expensive due to low yields. High power lasers are capable of machining these materials at far greater speeds. However, the performance of ceramic substrates is dependent on the quality of the processed region, with specific reference to the level of microcracking. The propagation of microcracks into the bulk substrate inevitably leads to component failure. Generation of Recast Layer microcracking is the Achilles heel of laser processing of ceramics. The fundamental process of laser radiation interaction with ceramic substrates generates a severe thermal gradient between the Recast Layer and bulk substrate. This in turn leads to the stresses which cause microcracks to form. Techniques for the reduction of this thermal shear have been investigated. Optimization of Nd:YAG laser drilling enabled repeatable and high quality processing to be undertaken. However, adaptation of these conventional techniques was required to reduce the l...
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nd yag laser drilling of 8 3 mm thick partially stabilized tetragonal zirconia control of Recast Layer microcracking using localized heating techniques
Journal of Laser Applications, 1999Co-Authors: A. J. Murray, John R. TyrerAbstract:The machining of ceramic components using conventional techniques is slow and expensive due to low yields. High power lasers are capable of machining these materials at far greater speeds. However, the performance of ceramic substrates is dependent on the quality of the processed region, with specific reference to the level of microcracking. The propagation of microcracks into the bulk substrate inevitably leads to component failure. Generation of Recast Layer microcracking is the Achilles heel of laser processing of ceramics. The fundamental process of laser radiation interaction with ceramic substrates generates a severe thermal gradient between the Recast Layer and bulk substrate. This in turn leads to the stresses which cause microcracks to form. Techniques for the reduction of this thermal shear have been investigated. Optimization of Nd:YAG laser drilling enabled repeatable and high quality processing to be undertaken. However, adaptation of these conventional techniques was required to reduce the l...
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Nd:YAG laser cutting and drilling of PSTZ—Influence of substrate heating temperature on Recast Layer microcracking
Journal of Laser Applications, 1999Co-Authors: A. J. Murray, John R. TyrerAbstract:The machining of ceramic components using conventional techniques is slow and expensive due to low yields. High power lasers are capable of machining these materials at far greater speeds. Recast Layer microcracking is the Achilles heel of laser processing of ceramics. Techniques for the reduction of the thermal shear caused by laser beam interaction have been investigated. A method for the numerical characterization of microcracking was developed for this work and was based upon scanning electron microscopy image processing. Optimization of the pulsed Nd:YAG laser drilling and cutting cycles enabled repeatable, high quality processing to be undertaken. Heating of the partially stabilized tetragonal zirconia (PSTZ) substrates to high temperatures before and after laser processing was found to reduce the thermal gradients that cause microcracking. Holes with a mean diameter of 679 μm were percussion drilled through the 8.3 mm thick substrates in 0.75 s, and had limited tapering (
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nd yag laser cutting and drilling of pstz influence of substrate heating temperature on Recast Layer microcracking
Journal of Laser Applications, 1999Co-Authors: A. J. Murray, John R. TyrerAbstract:The machining of ceramic components using conventional techniques is slow and expensive due to low yields. High power lasers are capable of machining these materials at far greater speeds. Recast Layer microcracking is the Achilles heel of laser processing of ceramics. Techniques for the reduction of the thermal shear caused by laser beam interaction have been investigated. A method for the numerical characterization of microcracking was developed for this work and was based upon scanning electron microscopy image processing. Optimization of the pulsed Nd:YAG laser drilling and cutting cycles enabled repeatable, high quality processing to be undertaken. Heating of the partially stabilized tetragonal zirconia (PSTZ) substrates to high temperatures before and after laser processing was found to reduce the thermal gradients that cause microcracking. Holes with a mean diameter of 679 μm were percussion drilled through the 8.3 mm thick substrates in 0.75 s, and had limited tapering (<150 μm). Single pass, full...
S. F. Hsieh - One of the best experts on this subject based on the ideXlab platform.
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EDM surface characteristics and shape recovery ability of Ti35.5Ni48.5Zr16 and Ni60Al24.5Fe15.5 ternary shape memory alloys
Journal of Alloys and Compounds, 2013Co-Authors: S. F. Hsieh, Shyh-leh Chen, Albert Wen-jeng Hsue, Keng Liang OuAbstract:Abstract Electro-discharge craters and Recast materials are observed in the electro-discharge machining (EDM) surface of Ti 35.5 Ni 48.5 Zr 16 and Ni 60 Al 24.5 Fe 15.5 alloys. The Recast Layer is composed of TiO, NiO, ZrO 2 , Fe 2 O 3 , Al 2 O 3. The hardening effect near the outer surface for EDMed TiNiZr alloy originates from the surface oxides of the Recast Layer. The thickness of the Recast Layer increases upon growing pulse energy. The EDMed Ti 35.5 Ni 48.5 Zr 16 alloy still exhibits a good shape recovery, but the shape recovery is slightly reduced due to the depression of the Recast Layer. The material removal rate (MRR) of Ti 35.5 Ni 48.5 Zr 16 alloy is less than that of Ni 60 Al 24.5 Fe 15.5 alloy because of the larger θ × k α value. A high discharge energy should have a larger and deeper craters, and a rougher surface. The surface roughness of the EDMed TiNiZr and NiAlFe SMAs is found to obey the empirical equation of Ra = C ( I P × τ P ) β . Having a larger θ × K α value, Ti 35.5 Ni 48.5 Zr 16 alloy has a lower Ra value than that of Ni 60 Al 24.5 Fe 15.5 alloy after electro-discharge machining.
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Electrical discharge machining of a NiAlFe ternary shape memory alloy
Journal of Alloys and Compounds, 2008Co-Authors: Shyh-leh Chen, M.-h. Lin, S. F. Hsieh, H. C. Lin, J. S. HuangAbstract:The electro-discharge machining (EDM) characteristics of a NiAlFe ternary shape memory alloy (SMA) have been investigated in this study. Experimental results reveal that the material removal rates (MRRs) of Ni60Al24.5Fe15.5 and Ti35.5Ni49.5Zr15 alloys in the EDM process exhibit a reverse relationship to the product of the alloy's melting temperature and thermal conductivity. In addition, a precise EDM machining of NiAlFe SMA can be obtained by setting the machine parameters at low pulse energy. The surface roughness (Ra) of the EDMed NiAlFe SMA is found to follow the empirical equation of Ra = λ(IP × τP)β. Having a less TΘ × KT value, Ni60Al24.5Fe15.5 alloy has a larger Ra value than that of Ti35.5Ni49.5Zr15 alloy after electro-discharge machining. The Recast Layer consists of the oxides Fe2O3, Al2O3, NiO and the deposition particles of the consumed Cu electrode and dissolved dielectric medium. The hardening effect near the outer surface for EDMed NiAlFe alloy originates from the Recast Layer. The thickness of the Recast Layer varies with the pulse duration and exhibits a minimum value at the maximal MRR. © 2007 Elsevier B.V. All rights reserved.
