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Adrian Leyland - One of the best experts on this subject based on the ideXlab platform.
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Triode Plasma Diffusion treatment of titanium alloys
Surface and Coatings Technology, 2012Co-Authors: Glenn Cassar, Allan Matthews, Adrian LeylandAbstract:Abstract In this paper the structure, properties and tribological behaviour of the binary β titanium alloy Ti–15Mo have been investigated. Low-pressure triode Plasma Diffusion processes were used to improve the wear resistance of this material and the results were compared with equivalent work carried out on the more popular and better known α + β alloy, Ti–6Al–4V. In order to study these materials, X-ray diffraction, micro- and nano-indentation hardness, surface profilometry, optical microscopy, electron backscatter diffraction and ball-on-plate reciprocating wear testing were employed. These techniques show stark differences between the two titanium alloys, not only in their structure and properties, but also in their response to the surface engineering treatments investigated. It was found that the relatively coarse-grained Ti–15Mo experiences a larger increase in surface roughness when Plasma Diffusion-treated, particularly where nitrogen is used to provide the active ionised gas species. However, physical vapour deposition (PVD) of a thin pure α -Ti layer can effectively reduce this roughening effect to acceptable levels without compromising the Diffusion treatment efficacy in terms of the case hardness and depth achieved. Once a thin PVD layer of α -Ti has been deposited onto the untreated Ti–15Mo, significant improvements in the wear resistance of this alloy can be achieved by either nitrogen Plasma-Diffusion treatment or by a duplex process routine which includes the final deposition of a hard PVD TiN ceramic coating. Furthermore, the results presented here show that triode Plasma oxidation is also a simple (yet very effective) method that can be used to drastically improve the tribological performance of this alloy, where the careful control of (oxide) compound layer formation can produce a hard and wear-resistant surface without the need for duplex PVD coating.
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Impact wear resistance of Plasma Diffusion treated and duplex treated/PVD-coated Ti–6Al–4V alloy
Surface and Coatings Technology, 2012Co-Authors: Glenn Cassar, Allan Matthews, Sarah Banfield, J Housden, J. C. Avelar Batista Wilson, Adrian LeylandAbstract:Abstract In this paper dynamic ball-on-plate impact wear testing is utilised to evaluate the intrinsic fatigue strength of the surface of triode Plasma Diffusion treated, single-layered TiN-, CrAlN-, and WC/C-coated and duplex Diffusion treated/PVD-coated Ti–6Al–4V. The test is used to assess the resistance of surfaces to dynamic, high-cycle loading caused by the repeated impact of a cemented carbide ball. The subsequent observation and comparison of the wear craters produced (and their measured volumes) was used to identify which Diffusion treatment (or treatment/coating combination) provided the most marked reduction in contact-induced deformation and overall improvement in wear behaviour. A combination of nanoindentation, Knoop hardness microindentation, scratch adhesion, stylus profilometry, optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and atomic force microscopy test and evaluation methods, was used to characterise the surfaces under investigation. Experimental results revealed that triode Plasma Diffusion treatments can provide exceptional improvements in the impact fatigue resistance, particularly when the Diffusion process has been designed to maximise the resultant hardened case depth. Also, amongst the three coatings tested, PVD CrAlN was found to be the most suitable for applications involving such dynamic impact loading. Finally, the results presented show that an appropriate sequential triode Plasma oxidation and nitriding Diffusion pretreatment, in combination with a hard and tough PVD ceramic coating, can provide a significant reduction in surface impact wear when compared to either Plasma Diffusion treatments alone, or PVD ceramic coatings deposited on non-pretreated Ti-alloy substrates.
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Micro-abrasion wear testing of triode Plasma Diffusion and duplex treated Ti–6Al–4V alloy
Wear, 2011Co-Authors: Glenn Cassar, Allan Matthews, Sarah Banfield, J Housden, J. C. Avelar Batista Wilson, Adrian LeylandAbstract:Abstract In this paper micro-abrasion wear testing is used to evaluate the wear resistance of triode Plasma Diffusion-treated, single-layered TiN-, CrAlN-, and WC/C-coated and duplex-Diffusion and coated Ti–6Al–4V under uniform three-body rolling abrasion. Nanoindentation, Knoop microhardness, mechanical surface profilometry, optical microscopy, scanning electron microscopy and atomic force microscopy, were used to characterise the surfaces under investigation. Optimum testing conditions for rolling abrasion were established by varying the test parameters and resultant severity of contact. Very low normal loads and high volume fractions of particles in the abrasive slurry are necessary to obtain predictable and reproducible results. Relatively coarse SiC abrasive particles, having a mean diameter of around 3 μm, appear more suitable for micro-abrasion testing of the samples investigated, compared to finer Al 2 O 3 particles. Problems associated with the measurement of the scar volume and subsequent calculation of the wear rate for hard coatings deposited on relatively soft metals like titanium are identified, and suitable testing and measurement techniques are suggested. Three-dimensional wear scar maps generated by mechanical stylus profilometry were used to measure the wear volumes. Under the test conditions used, wear coefficients can be determined from perforating and non-perforating tests, although perforating tests provide more consistent results. Triode Plasma Diffusion treatments, Plasma-assisted (PA) PVD TiN and PAPVD CrAlN can reduce the specific wear rate of Ti–6Al–4V, while PACVD-based WC/C coatings do not provide suitable protection against abrasive wear. The combination of triode Plasma oxynitriding Diffusion treatments and PVD coatings to create duplex treatments can also lead to further reductions in the coating wear coefficient when compared to non-duplex coatings deposited on non-pretreated substrates.
Glenn Cassar - One of the best experts on this subject based on the ideXlab platform.
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impact wear resistance of Plasma Diffusion treated and duplex treated pvd coated ti 6al 4v alloy
Surface & Coatings Technology, 2012Co-Authors: Glenn Cassar, Sarah Banfield, J Avelar Batista C Wilson, J Housden, A Matthews, A LeylandAbstract:Abstract In this paper dynamic ball-on-plate impact wear testing is utilised to evaluate the intrinsic fatigue strength of the surface of triode Plasma Diffusion treated, single-layered TiN-, CrAlN-, and WC/C-coated and duplex Diffusion treated/PVD-coated Ti–6Al–4V. The test is used to assess the resistance of surfaces to dynamic, high-cycle loading caused by the repeated impact of a cemented carbide ball. The subsequent observation and comparison of the wear craters produced (and their measured volumes) was used to identify which Diffusion treatment (or treatment/coating combination) provided the most marked reduction in contact-induced deformation and overall improvement in wear behaviour. A combination of nanoindentation, Knoop hardness microindentation, scratch adhesion, stylus profilometry, optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and atomic force microscopy test and evaluation methods, was used to characterise the surfaces under investigation. Experimental results revealed that triode Plasma Diffusion treatments can provide exceptional improvements in the impact fatigue resistance, particularly when the Diffusion process has been designed to maximise the resultant hardened case depth. Also, amongst the three coatings tested, PVD CrAlN was found to be the most suitable for applications involving such dynamic impact loading. Finally, the results presented show that an appropriate sequential triode Plasma oxidation and nitriding Diffusion pretreatment, in combination with a hard and tough PVD ceramic coating, can provide a significant reduction in surface impact wear when compared to either Plasma Diffusion treatments alone, or PVD ceramic coatings deposited on non-pretreated Ti-alloy substrates.
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Triode Plasma Diffusion treatment of titanium alloys
Surface and Coatings Technology, 2012Co-Authors: Glenn Cassar, Allan Matthews, Adrian LeylandAbstract:Abstract In this paper the structure, properties and tribological behaviour of the binary β titanium alloy Ti–15Mo have been investigated. Low-pressure triode Plasma Diffusion processes were used to improve the wear resistance of this material and the results were compared with equivalent work carried out on the more popular and better known α + β alloy, Ti–6Al–4V. In order to study these materials, X-ray diffraction, micro- and nano-indentation hardness, surface profilometry, optical microscopy, electron backscatter diffraction and ball-on-plate reciprocating wear testing were employed. These techniques show stark differences between the two titanium alloys, not only in their structure and properties, but also in their response to the surface engineering treatments investigated. It was found that the relatively coarse-grained Ti–15Mo experiences a larger increase in surface roughness when Plasma Diffusion-treated, particularly where nitrogen is used to provide the active ionised gas species. However, physical vapour deposition (PVD) of a thin pure α -Ti layer can effectively reduce this roughening effect to acceptable levels without compromising the Diffusion treatment efficacy in terms of the case hardness and depth achieved. Once a thin PVD layer of α -Ti has been deposited onto the untreated Ti–15Mo, significant improvements in the wear resistance of this alloy can be achieved by either nitrogen Plasma-Diffusion treatment or by a duplex process routine which includes the final deposition of a hard PVD TiN ceramic coating. Furthermore, the results presented here show that triode Plasma oxidation is also a simple (yet very effective) method that can be used to drastically improve the tribological performance of this alloy, where the careful control of (oxide) compound layer formation can produce a hard and wear-resistant surface without the need for duplex PVD coating.
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Impact wear resistance of Plasma Diffusion treated and duplex treated/PVD-coated Ti–6Al–4V alloy
Surface and Coatings Technology, 2012Co-Authors: Glenn Cassar, Allan Matthews, Sarah Banfield, J Housden, J. C. Avelar Batista Wilson, Adrian LeylandAbstract:Abstract In this paper dynamic ball-on-plate impact wear testing is utilised to evaluate the intrinsic fatigue strength of the surface of triode Plasma Diffusion treated, single-layered TiN-, CrAlN-, and WC/C-coated and duplex Diffusion treated/PVD-coated Ti–6Al–4V. The test is used to assess the resistance of surfaces to dynamic, high-cycle loading caused by the repeated impact of a cemented carbide ball. The subsequent observation and comparison of the wear craters produced (and their measured volumes) was used to identify which Diffusion treatment (or treatment/coating combination) provided the most marked reduction in contact-induced deformation and overall improvement in wear behaviour. A combination of nanoindentation, Knoop hardness microindentation, scratch adhesion, stylus profilometry, optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and atomic force microscopy test and evaluation methods, was used to characterise the surfaces under investigation. Experimental results revealed that triode Plasma Diffusion treatments can provide exceptional improvements in the impact fatigue resistance, particularly when the Diffusion process has been designed to maximise the resultant hardened case depth. Also, amongst the three coatings tested, PVD CrAlN was found to be the most suitable for applications involving such dynamic impact loading. Finally, the results presented show that an appropriate sequential triode Plasma oxidation and nitriding Diffusion pretreatment, in combination with a hard and tough PVD ceramic coating, can provide a significant reduction in surface impact wear when compared to either Plasma Diffusion treatments alone, or PVD ceramic coatings deposited on non-pretreated Ti-alloy substrates.
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Micro-abrasion wear testing of triode Plasma Diffusion and duplex treated Ti–6Al–4V alloy
Wear, 2011Co-Authors: Glenn Cassar, Allan Matthews, Sarah Banfield, J Housden, J. C. Avelar Batista Wilson, Adrian LeylandAbstract:Abstract In this paper micro-abrasion wear testing is used to evaluate the wear resistance of triode Plasma Diffusion-treated, single-layered TiN-, CrAlN-, and WC/C-coated and duplex-Diffusion and coated Ti–6Al–4V under uniform three-body rolling abrasion. Nanoindentation, Knoop microhardness, mechanical surface profilometry, optical microscopy, scanning electron microscopy and atomic force microscopy, were used to characterise the surfaces under investigation. Optimum testing conditions for rolling abrasion were established by varying the test parameters and resultant severity of contact. Very low normal loads and high volume fractions of particles in the abrasive slurry are necessary to obtain predictable and reproducible results. Relatively coarse SiC abrasive particles, having a mean diameter of around 3 μm, appear more suitable for micro-abrasion testing of the samples investigated, compared to finer Al 2 O 3 particles. Problems associated with the measurement of the scar volume and subsequent calculation of the wear rate for hard coatings deposited on relatively soft metals like titanium are identified, and suitable testing and measurement techniques are suggested. Three-dimensional wear scar maps generated by mechanical stylus profilometry were used to measure the wear volumes. Under the test conditions used, wear coefficients can be determined from perforating and non-perforating tests, although perforating tests provide more consistent results. Triode Plasma Diffusion treatments, Plasma-assisted (PA) PVD TiN and PAPVD CrAlN can reduce the specific wear rate of Ti–6Al–4V, while PACVD-based WC/C coatings do not provide suitable protection against abrasive wear. The combination of triode Plasma oxynitriding Diffusion treatments and PVD coatings to create duplex treatments can also lead to further reductions in the coating wear coefficient when compared to non-duplex coatings deposited on non-pretreated substrates.
A Leyland - One of the best experts on this subject based on the ideXlab platform.
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impact wear resistance of Plasma Diffusion treated and duplex treated pvd coated ti 6al 4v alloy
Surface & Coatings Technology, 2012Co-Authors: Glenn Cassar, Sarah Banfield, J Avelar Batista C Wilson, J Housden, A Matthews, A LeylandAbstract:Abstract In this paper dynamic ball-on-plate impact wear testing is utilised to evaluate the intrinsic fatigue strength of the surface of triode Plasma Diffusion treated, single-layered TiN-, CrAlN-, and WC/C-coated and duplex Diffusion treated/PVD-coated Ti–6Al–4V. The test is used to assess the resistance of surfaces to dynamic, high-cycle loading caused by the repeated impact of a cemented carbide ball. The subsequent observation and comparison of the wear craters produced (and their measured volumes) was used to identify which Diffusion treatment (or treatment/coating combination) provided the most marked reduction in contact-induced deformation and overall improvement in wear behaviour. A combination of nanoindentation, Knoop hardness microindentation, scratch adhesion, stylus profilometry, optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and atomic force microscopy test and evaluation methods, was used to characterise the surfaces under investigation. Experimental results revealed that triode Plasma Diffusion treatments can provide exceptional improvements in the impact fatigue resistance, particularly when the Diffusion process has been designed to maximise the resultant hardened case depth. Also, amongst the three coatings tested, PVD CrAlN was found to be the most suitable for applications involving such dynamic impact loading. Finally, the results presented show that an appropriate sequential triode Plasma oxidation and nitriding Diffusion pretreatment, in combination with a hard and tough PVD ceramic coating, can provide a significant reduction in surface impact wear when compared to either Plasma Diffusion treatments alone, or PVD ceramic coatings deposited on non-pretreated Ti-alloy substrates.
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Micro-abrasion wear testing of triode Plasma Diffusion and duplex treated Ti–6Al–4V alloy
Wear, 2012Co-Authors: G. Cassar, Sarah Banfield, J Housden, A Matthews, J.c. Avelar-batista Wilson, A LeylandAbstract:The authors gratefully acknowledge financial support for this\ud \ud research work from the UK Technology Strategy Board, under Tech-\ud nology Programme project TP/22076, in collaboration with Tecvac\ud \ud Ltd., NMB-Minebea UK Ltd. and Airbus UK.In this paper micro-abrasion wear testing is used to evaluate the wear resistance of triode Plasma\ud \ud Diffusion-treated, single-layered TiN-, CrAlN-, and WC/C-coated and duplex-Diffusion and coated\ud \ud Ti–6Al–4V under uniform three-body rolling abrasion. Nanoindentation, Knoop microhardness, mechan-\ud ical surface profilometry, optical microscopy, scanning electron microscopy and atomic force microscopy,\ud \ud were used to characterise the surfaces under investigation. Optimum testing conditions for rolling abra-\ud sion were established by varying the test parameters and resultant severity of contact. Very low normal\ud \ud loads and high volume fractions of particles in the abrasive slurry are necessary to obtain predictable and\ud \ud reproducible results. Relatively coarse SiC abrasive particles, having a mean diameter of around 3 m,\ud \ud appear more suitable for micro-abrasion testing of the samples investigated, compared to finer Al2O3\ud \ud particles. Problems associated with the measurement of the scar volume and subsequent calculation of\ud \ud the wear rate for hard coatings deposited on relatively soft metals like titanium are identified, and suit-\ud able testing and measurement techniques are suggested. Three-dimensional wear scar maps generated\ud \ud by mechanical stylus profilometry were used to measure the wear volumes. Under the test conditions\ud \ud used, wear coefficients can be determined from perforating and non-perforating tests, although perforat-\ud ing tests provide more consistent results. Triode Plasma Diffusion treatments, Plasma-assisted (PA) PVD\ud \ud TiN and PAPVD CrAlN can reduce the specific wear rate of Ti–6Al–4V, while PACVD-based WC/C coatings\ud \ud do not provide suitable protection against abrasive wear. The combination of triode Plasma oxynitriding\ud \ud Diffusion treatments and PVD coatings to create duplex treatments can also lead to further reductions\ud \ud in the coating wear coefficient when compared to non-duplex coatings deposited on non-pretreated\ud \ud substrates.peer-reviewe
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a comparative study of the influence of Plasma treatments pvd coatings and ion implantation on the tribological performance of ti 6al 4v
Surface & Coatings Technology, 1999Co-Authors: A D Wilson, A Leyland, A MatthewsAbstract:Abstract The mechanical and tribological properties of the titanium alloy Ti–6Al–4V have been characterized by low-frequency reciprocating wear, rotating–bending fatigue and Knoop microhardness tests and surface roughness (Ra) measurements before and after various treatments. These treatments included ion-beam nitrogen implantation, Plasma-assisted physical vapour deposition (PAPVD) of TiN and Plasma Diffusion of nitrogen and carbon. Using a commercial thermionic triode Plasma-assisted PVD system, hot-filament-supported glow discharges were produced with different compositions of nitrogen, carbon and hydrogen. The Plasma-Diffusion treatments all increased the load support provided by the substrate but reduced the bulk fatigue stength considerably. The PAPVD TiN coating increased surface microhardness but provided limited load support. Nitrogen-ion implantation increased low-load surface microhardnesses and improved the fatigue resistance without improving the overall load support provided by the substrate. It was found that the elevated temperatures and increased process times in Plasma-Diffusion treatments increased the surface roughness significantly, although this roughening effect could be reduced by depositing a thin titanium layer by PAPVD, prior to the Plasma treatment.
K.-t. Rie - One of the best experts on this subject based on the ideXlab platform.
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Improvement in the load-bearing capacity and adhesion of TiC coatings on TiAl6V4 by duplex treatment
Surface & Coatings Technology, 2001Co-Authors: P. Kaestner, J. Olfe, K.-t. RieAbstract:Abstract It is shown that the use of nitrogen or carbon as alloying elements in Plasma Diffusion treatment of TiAl6V4 is beneficial for the load-supporting properties of the base material. The Plasma Diffusion treatment produces a compound layer consisting of nitrides or carbides and an inner Diffusion zone, essentially characterized by the presence of nitrogen- or carbon-rich α-Ti crystals which are embedded in the metal matrix. This results in a hardness gradient from the interior to the surface. To avoid hydrogen embrittlement, Plasma nitriding is performed in a pure nitrogen atmosphere. The formation of soot by carburizing could be avoided by optimizing the carbon flow during Plasma carburizing. The influence of Plasma nitriding and carburizing on the adhesion of the TiC coating depends on the Plasma Diffusion pretreatment and the conditions of the TiC coating. Plasma-nitrocarburizing pretreatment leads to the best adhesion of the TiC coating; the critical load of failure is 80% higher than in the case of TiC on base material. A critical load of approximately 33 N was found under the optimum parameters. We conclude that the combination of Plasma Diffusion treatment and TiC coating extends the tribological applicability of TiAl6V4 in many industrial sectors. Fretting fatigue and wear could be increased by a duplex Plasma treatment combined with shot peening.
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Recent advances in Plasma Diffusion processes
Surface and Coatings Technology, 1999Co-Authors: K.-t. RieAbstract:Although Plasma Diffusion treatment (PDT) is one of the most promising and economical processes to improve both surface and near-surface properties such as wear and corrosion resistance and fatigue strength, the basic mechanisms are still poorly understood. Despite this fact, significant improvements have been made in equipment and processes. In the present paper, the state-of-the-art and the recent progress in Plasma Diffusion treatment will be reported. This paper will especially highlight the recent accomplishments in Plasma carburizing and Plasma boriding. The new trends of applications in Plasma Diffusion treatment will be described to show the future perspectives of this technology.
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Plasma Diffusion treatment of stellite
Surface & Coatings Technology, 1995Co-Authors: Y.s. Kim, J.r. Park, E. Menthe, K.-t. RieAbstract:Abstract Stellite, a Co-base superalloy, exhibits good resistance to wear and corrosion. However, this good resistance to wear is sometimes less pronounced in some industrial applications such as steel mill equipment. The present study was therefore conducted to improve this impoverishment of wear property of Stellite. The maximum hardness after Plasma nitriding was measured as 1300 HK 0.01, which was facilitated by the formation of CrN. It was found that Plasma nitriding at 823 K exhibited relatively higher hardness and a thinner compound layer than Plasma nitriding at 973 K. However, the hardness decreased drastically at 1073 K. Plasma nitrocarburizing was also applied with the parameters of optimized conditions for Plasma nitriding with the addition of methane gas to arc 80%N2H2 gas mixture. The maximum hardness after Plasma nitrocarburizing was about 1200 HK 0.01 and the thickness of layer was about 30 μm while it was 8 μm after Plasma nitriding. It was indicated that carbon was uniformly distributed in the Diffusion layer while the distribution of nitrogen was rich only at the compound layer. Surface conditions after Plasma Diffusion treatment are also discussed.
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Plasma Diffusion treatment and duplex treatment — recent development and new applications
Surface and Coatings Technology, 1995Co-Authors: K.-t. Rie, Erhard BroszeitAbstract:Abstract Plasma Diffusion treatment (PDT) is one of the most promising methods for improving both the surface and the near-surface properties. The duplex treatment combining the Plasma Diffusion with PVD or PACVD provides an excellent method for achieving optimal properties of the surface and the near surface and allows the design of a layer system to meet the increased demands of functional surfaces. In the present review, recent investigations of the Plasma Diffusion treatment of ferrous and non-ferrous materials are reported. For austenitic steel, Ti alloys, Co base alloys and Cr coating, Plasma Diffusion treatment has been carried out. In the case of austenitic steel, processes are optimized to achieve improved wear resistance, retaining the excellent corrosion resistance of the steel. While the wear resistance and the friction properties were mainly of interest for stellite 6B, in addition the corrosion resistance has been investigated for Cr coating on steels after Plasma Diffusion treatment. The Ti alloy TiAl6V4 showing a gradient layer system after Plasma nitriding has been duplex treated by adopting PACVD. The microstructure, wear and friction as well as corrosion behaviour have been investigated and the results of biocompatibility testing are presented briefly.
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Influence of pulsed d.c.-glow-discharge on the phase constitution of nitride layers during Plasma nitrocarburizing of sintered materials
Materials Science and Engineering: A, 1991Co-Authors: K.-t. Rie, F. SchnatbaumAbstract:Abstract In the past it was shown that Plasma Diffusion treatment of sintered materials has several advantages over conventional processes such as gas or salt bath nitriding and nitrocarburizing. The large number of parameters in Plasma Diffusion treatment allows close control of the process so that surface layers with defined microstructures and properties can be obtained. During Plasma Diffusion treatment the phase constitution of the nitride compound layer can be influenced by varying the gas mixture. By using a pulsed d.c. glow discharge the phase constitution and the microstructure of the compound layer can be influenced by varying the pulse duration and pulse repetition time. The number of micropores in the compound layer can be reduced in a pulsed d.c. glow discharge by pulsing the Plasma, i.e. by reducing the Plasma power. The phase constitution can be influenced by the pulse duration and pulse repetition time. With short pulse duration and long pulse repetition time the formation of Fe 3 C in the compound layer can be suppressed. The amount of γ′ and e phase present can be influenced.
A Matthews - One of the best experts on this subject based on the ideXlab platform.
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impact wear resistance of Plasma Diffusion treated and duplex treated pvd coated ti 6al 4v alloy
Surface & Coatings Technology, 2012Co-Authors: Glenn Cassar, Sarah Banfield, J Avelar Batista C Wilson, J Housden, A Matthews, A LeylandAbstract:Abstract In this paper dynamic ball-on-plate impact wear testing is utilised to evaluate the intrinsic fatigue strength of the surface of triode Plasma Diffusion treated, single-layered TiN-, CrAlN-, and WC/C-coated and duplex Diffusion treated/PVD-coated Ti–6Al–4V. The test is used to assess the resistance of surfaces to dynamic, high-cycle loading caused by the repeated impact of a cemented carbide ball. The subsequent observation and comparison of the wear craters produced (and their measured volumes) was used to identify which Diffusion treatment (or treatment/coating combination) provided the most marked reduction in contact-induced deformation and overall improvement in wear behaviour. A combination of nanoindentation, Knoop hardness microindentation, scratch adhesion, stylus profilometry, optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and atomic force microscopy test and evaluation methods, was used to characterise the surfaces under investigation. Experimental results revealed that triode Plasma Diffusion treatments can provide exceptional improvements in the impact fatigue resistance, particularly when the Diffusion process has been designed to maximise the resultant hardened case depth. Also, amongst the three coatings tested, PVD CrAlN was found to be the most suitable for applications involving such dynamic impact loading. Finally, the results presented show that an appropriate sequential triode Plasma oxidation and nitriding Diffusion pretreatment, in combination with a hard and tough PVD ceramic coating, can provide a significant reduction in surface impact wear when compared to either Plasma Diffusion treatments alone, or PVD ceramic coatings deposited on non-pretreated Ti-alloy substrates.
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Micro-abrasion wear testing of triode Plasma Diffusion and duplex treated Ti–6Al–4V alloy
Wear, 2012Co-Authors: G. Cassar, Sarah Banfield, J Housden, A Matthews, J.c. Avelar-batista Wilson, A LeylandAbstract:The authors gratefully acknowledge financial support for this\ud \ud research work from the UK Technology Strategy Board, under Tech-\ud nology Programme project TP/22076, in collaboration with Tecvac\ud \ud Ltd., NMB-Minebea UK Ltd. and Airbus UK.In this paper micro-abrasion wear testing is used to evaluate the wear resistance of triode Plasma\ud \ud Diffusion-treated, single-layered TiN-, CrAlN-, and WC/C-coated and duplex-Diffusion and coated\ud \ud Ti–6Al–4V under uniform three-body rolling abrasion. Nanoindentation, Knoop microhardness, mechan-\ud ical surface profilometry, optical microscopy, scanning electron microscopy and atomic force microscopy,\ud \ud were used to characterise the surfaces under investigation. Optimum testing conditions for rolling abra-\ud sion were established by varying the test parameters and resultant severity of contact. Very low normal\ud \ud loads and high volume fractions of particles in the abrasive slurry are necessary to obtain predictable and\ud \ud reproducible results. Relatively coarse SiC abrasive particles, having a mean diameter of around 3 m,\ud \ud appear more suitable for micro-abrasion testing of the samples investigated, compared to finer Al2O3\ud \ud particles. Problems associated with the measurement of the scar volume and subsequent calculation of\ud \ud the wear rate for hard coatings deposited on relatively soft metals like titanium are identified, and suit-\ud able testing and measurement techniques are suggested. Three-dimensional wear scar maps generated\ud \ud by mechanical stylus profilometry were used to measure the wear volumes. Under the test conditions\ud \ud used, wear coefficients can be determined from perforating and non-perforating tests, although perforat-\ud ing tests provide more consistent results. Triode Plasma Diffusion treatments, Plasma-assisted (PA) PVD\ud \ud TiN and PAPVD CrAlN can reduce the specific wear rate of Ti–6Al–4V, while PACVD-based WC/C coatings\ud \ud do not provide suitable protection against abrasive wear. The combination of triode Plasma oxynitriding\ud \ud Diffusion treatments and PVD coatings to create duplex treatments can also lead to further reductions\ud \ud in the coating wear coefficient when compared to non-duplex coatings deposited on non-pretreated\ud \ud substrates.peer-reviewe
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a comparative study of the influence of Plasma treatments pvd coatings and ion implantation on the tribological performance of ti 6al 4v
Surface & Coatings Technology, 1999Co-Authors: A D Wilson, A Leyland, A MatthewsAbstract:Abstract The mechanical and tribological properties of the titanium alloy Ti–6Al–4V have been characterized by low-frequency reciprocating wear, rotating–bending fatigue and Knoop microhardness tests and surface roughness (Ra) measurements before and after various treatments. These treatments included ion-beam nitrogen implantation, Plasma-assisted physical vapour deposition (PAPVD) of TiN and Plasma Diffusion of nitrogen and carbon. Using a commercial thermionic triode Plasma-assisted PVD system, hot-filament-supported glow discharges were produced with different compositions of nitrogen, carbon and hydrogen. The Plasma-Diffusion treatments all increased the load support provided by the substrate but reduced the bulk fatigue stength considerably. The PAPVD TiN coating increased surface microhardness but provided limited load support. Nitrogen-ion implantation increased low-load surface microhardnesses and improved the fatigue resistance without improving the overall load support provided by the substrate. It was found that the elevated temperatures and increased process times in Plasma-Diffusion treatments increased the surface roughness significantly, although this roughening effect could be reduced by depositing a thin titanium layer by PAPVD, prior to the Plasma treatment.