Browsing by Author "Bailey, Richard"
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Item Open Access Comparison of wear performance of low temperature nitrided and carburized 316L stainless steel under dry sliding and corrosive-wear conditions(Springer Nature, 2022-07-29) Sun, Yong; Bailey, Richard316L austenitic stainless steel was plasma nitrided and carburized at low temperatures to produce precipitation-free nitrided and carburized layers, respectively. The reciprocation sliding wear performances of the untreated, nitrided and carburized specimens were compared under both unlubricated (dry) and corrosive (in 0.5M H2SO4 solution) conditions. The results show that under dry sliding conditions, both the nitrided layer and carburized layer can offer good wear resistance to 316L steel. The total material loss (TML) of the steel is reduced by more than two orders of magnitude by low temperature nitriding, while low temperature carburizing offers a reduction in TML by an order of magnitude. The better dry sliding wear performance of the nitrided layer is attributed to its much higher hardness as compared to the carburized layer. However, under corrosive-wear conditions in 0.5 M H2SO4 solution, the wear performance of the nitrided layer is significantly deteriorated, with TML 100% higher than that of the untreated 316L steel. On the other hand, the carburized layer can still offer good wear resistance in the corrosive environment, with a reduction in TML of 316L steel by 40%. This research has practical implication that low temperature nitriding is the most suitable for applications in dry and non-corrosive environments, while low temperature carburizing is more suitable for applications in H2SO4-containing corrosive environments.Item Open Access Corrosion and Tribocorrosion Performance of Pack-Carburized Commercially Pure Titanium with Limited Oxygen Diffusion in a 0.9% NaCl Solution(Springer International Publishing, 2017-12-12) Bailey, Richard; Sun, YongIn the research presented, the corrosion and tribocorrosion characteristics of pack carburized titanium with limited oxygen diffusion (PCOD-Ti) has been investigated using a 0.9 % NaCl solution. The carburization treatment was undertaken using a service temperature of 925 ℃ for duration of 20 h. The treatment resulted in the creation of a titanium carbide (TiC) network layer atop an extended oxygen diffusion zone (ODZ) (α-Ti(O)). Electrochemical testing indicated the treated titanium surface offered slightly enhanced corrosion resistance over that of untreated titanium. Tribocorrosion testing of the PCOD-Ti was conducted by sliding the titanium against an alumina counter-face under a contact load of 20 N, with various anodic and cathodic potentials applied. The testing showed a dramatic reduction in the wear rate for the treated titanium. Wear rates were reduced by an order of magnitude when compared with the untreated samples. During testing an interesting cathodic protection was encountered. When subjected to high negative charge the wear rates of the treated titanium were reduced further. This reduced wear was attributed to the formation of titanium hydride within the wear track.Item Metadata only Corrosion and tribocorrosion performance of thermally oxidized commercial pure titanium in a 0.9% NaCl solution(Springer, 2015) Bailey, Richard; Sun, YongIn the present work, the corrosion and tribocorrosion characteristics of thermally oxidized commercially pure titanium in a 0.9% NaCl solution have been investigated. Thermal oxidation (TO) of CP-Ti was carried out at a temperature of 625C for 20 h. This treatment results in a multi-layered structure consisting of a 1lm rutile (TiO2) film and a 9lma-titanium oxygen diffusion zone (ODZ) (a-Ti(O)). Electrochemical tests were carried out on surfaces created at various depths from the TO-Ti original surface. It was found that the rutile film generated through TO offers excellent corrosion resistance over that of untreated Ti. Testing also provided evidence that oxygen content in the upper part of the ODZ (depths<5lm from the surface) helps accelerate passive film formation and thus reduce the corrosion of CP-Ti. Tribo-electrochemical testing of TO-Ti was carried out against an alumina counterface under a load of 2 N andvarious anodic andcathodic potentials. It is initially shown that the rutile oxide layeroffers both low friction and much better resistance to material removal during tribocorrosion than untreated CP-Ti. During sliding wear at open circuit potential, four frictional zones can be identified in a typical friction curve, each having its own characteristics corresponding to the oxide layer, the gradual or partial removal of the oxide layer, the diffusion zone, and the substrate. An unusual anodic protection behavior of the oxide film has also been observed. When the TO-Ti is polarized anodically during sliding, the durability of the oxide layer is prolonged, resulting in low friction and much reduced material loss. When cathodically charged to21500 mV SCE during sliding, both the TO-Ti and untreated CP-Ti experience a reduction in material loss. This is believed to be related to hydrogen evolution and titanium hydride formation.Item Embargo Corrosive-wear performance of grade 316 stainless steel sliding against grade 316 stainless steel in NaCl solution(Springer, 2023-12-19) Bailey, Richard; Sun, YongMost of the reported corrosive-wear or tribocorrosion tests have been carried out using an inert and insulating counter-body in the experimental set up, with the purpose of eliminating the direct contribution of the counter-body to the electrochemical response during sliding wear. Little work has been reported using the same material as the test specimen and as the counter-body. In this work, corrosive-wear experiments have been carried out on the same material contact, i.e., stainless steel on stainless steel (SS-SS), where a 316 SS specimen was sliding against a 316 SS slider in 0.5 M NaCl solution under controlled electrochemical conditions. For comparison purpose, similar experiments have also been conducted on the 316 SS-Al2O3 sliding pair. The tests were conducted under reciprocating sliding conditions at 1 Hz frequency, 4 N load and for a duration of 7200 s, incorporated with electrochemical control which included potentiodynamic polarization and potentiostatic polarization at constant negative and positive potentials with respect to the open circuit potential (OCP). The results show that the counter-body has a large effect on the corrosive-wear behaviour of the 316 SS specimen under all test conditions. As compared to the SS-Al2O3 sliding pair, the SS-SS pair experiences larger material removal from the specimen. Adhesive wear occurs in the SS-SS pair which leads to significantly roughened sliding surfaces and unstable frictional behavior and electrochemical response. Further analysis revealed that mechanical wear plays a more dominant role in material removal in the SS-SS pair than in the SS-Al2O3 pair, and it is the corrosion-accelerated wear that contributes to the significantly increased material removal in the SS-SS pair.Item Metadata only Dimensions of difference(Willan Publishing, 2004) Kemshall, Hazel, 1958-; Canton, Robert; Bailey, RichardItem Open Access Dry sliding wear and friction performance of zirconium dioxide tribopairs(Frontiers, 2024-04-12) Bailey, Richard; Yong, SunZirconium is an attractive engineering material owing to its commendable temperature, corrosion resistance, and excellent biocompatibility. Despite these merits, its industrial applicability is hindered by elevated wear and friction in tribological settings. Previous research has concentrated on unmatched pair contacts involving zirconium and alumina primarily due to the exceptional hardness. However, there is a noticeable dearth of literature on the matched pair contact condition for zirconium dioxide. Thermal oxidation is a promising and cost-effective method to address the suboptimal tribological performance and enhance the mechanical and electrochemical properties of zirconium. In this study, thermal oxidation is employed to produce a 6-μm-thick oxide layer in an air furnace at 650°C for 6 h. Subsequently, the resulting surface coating was tribologically tested using a pin-on-disc tribometer against two distinct counterface materials, namely, alumina and zirconium dioxide, in a dry and unlubricated environment. The findings reveal that matched contact between the zirconium dioxide tribopair is unfavorable, leading to elevated friction and wear rates. Consequently, this configuration should be avoided in dry contact situations characterized by high contact pressures. However, under lower contact pressures, the wear performance is acceptable. Furthermore, when combined with lubrication, this system may have potential applications in bio-tribological systems.Item Open Access Effect of Applied Cathodic Potential on Friction and Wear Behavior of CoCrMo Alloy in NaCl Solution(MDPI, 2020-11-23) Sun, Yong; Bailey, RichardMost of the reported work on the effect of applied potential on tribocorrosion or corrosive wear of metallic alloys in a corrosive environment were conducted at anodic potentials. Limited tests have been conducted at cathodic potentials for comparison purposes or to derive the pure mechanical wear component in tribocorrosion. This work investigated the effect of cathodic potential on the friction and wear behaviour of an important biomedical alloy, CoCrMo, sliding against an Al2O3 slider in 0.9% NaCl solution at 37 C. High friction was found at cathodic potentials close to the open circuit potential, where mechanical wear played a predominant role in material removal. At potentials more cathodic than the hydrogen charging potential, low friction and low wear were observed. The coefficient of friction (COF) and total material loss decreased with increasing cathodic potential, such that at -1000 mV (saturated calomel electrode, SCE), extremely low COF values, as low as 0.02, and negligible material loss were obtained. Such reductions in friction and wear at increasing cathodic potentials were accompanied with the formation of parallel lines in the sliding track and were gradually diminished with increasing applied contact load. It is believed that hydrogen charging and hydrogen segregated layer formation at the surface are responsible for such a phenomenon. It can also be concluded that it is difficult to derive the pure mechanical wear component in tribocorrosion by simply conducting a test at an arbitrary cathodic potential.Item Open Access Effect of Sliding Conditions on Micropitting Behaviour of AISI 304 Stainless Steel in Chloride Containing Solution(Elsevier, 2018-05-08) Sun, Yong; Bailey, RichardThe tribo-electrochemical behaviour of AISI 304 austenitic stainless steel in 0.5M NaCl solution is investigated at an anodic potential of 70 mV(SCE) under controlled sliding and electrochemical conditions. It is found that at such an anodic potential where corrosion pits do not form without sliding, numerous micro-pits are found inside the sliding tracks under certain sliding conditions. There exists a critical combination of frequency, load and sliding duration for the development of the pits. The results are discussed considering the accumulation of mechanical damages induced by sliding and the competition between wear and pit growth during the process.Item Open Access Effect of sliding conditions on the macroscale lubricity of multilayer graphene coatings grown on nickel by CVD(Elsevier, 2018-11-17) Sun, Yong; Kandan, K.; Shivareddy, S.; Farukh, Farukh; Bailey, RichardA multilayer graphene (MLG) coating was grown on a nickel substrate by atmospheric chemical vapor deposition (CVD). The macroscale dry sliding friction behavior of the coated specimens against a stainless steel counterface was investigated under various contact loads ranging from 1 N to 5 N and at various rotational speeds from 30 rpm to 240 rpm. After the tests, the sliding surfaces were characterized by optical and scanning electron microscopes and Raman spectroscopy. The results show that contact load and sliding speed had significant effects on the lubricity of the MLG coatings under dry sliding conditions. At relatively low contact loads (1-3 N) and sliding speeds (30-120 rpm), the MLG coating exhibited good lubricity with coefficient of friction (COF) below 0.06 and lasted a long period of sliding time for more than 3600 cycles. With increasing contact loads and speeds, the COF of the MLG coating was gradually increased and the coating suffered from sudden breakdown after limited sliding cycles, losing its lubricity. Detailed examination and analysis revealed that material transfer occurred at the early stage of the sliding process, where MLG was transferred from the coating surface to the counterface. This graphene transfer was responsible for the lubricity of the sliding pair and the sustainability of the transferred material on the counterface determined the lifetime of the lubricity regime. High contact loads and high speeds favored severe plastic deformation and mechanical damages of the substrate, which limited the lifetime of the transferred material and thus the lifetime of the lubricity regime. Sliding induced defects in the MLG both on the coating and on the counterface were confirmed by Raman spectroscopy.Item Open Access Effect of thermal oxidation on the dry sliding friction and wear behaviour of CP‑Ti on CP‑Ti tribopairs(2023-11-22) Sun, Yong; Bailey, Richard; Zhang, Jin; Lian, Yong; Ji, XiulinThermal oxidation (TO) has proven to be a cost-effective and efficient technique to engineer the surfaces of titanium and its alloys to achieve enhanced surface properties. The benefits of TO treatment in enhancing the tribological properties of titanium have been demonstrated by many investigators. However, most of the reported tribological studies have been based on the contact between a TO treated titanium specimen and a counter-body made of other materials, mainly ceramics, steels and polymers. Very few studies have been reported on the friction and wear behaviour of TO treated titanium sliding against TO treated titanium. In this work, the effect of thermal oxidation on the dry sliding friction and wear behaviour of commercially pure Ti (CP-Ti) on CP-Ti tribopairs was investigated under loading conditions ranging from elastic contact to plastic contact. Comparisons were made among three contact pairs: (1) untreated Ti on untreated Ti (Ti–Ti), (2) untreated Ti on TO treated Ti (Ti-TO) and (3) TO treated Ti on TO treated Ti (TO-TO). The results show that the TO-TO contact pair presents an ideal material combination to achieve the best tribological performance in terms of low friction and superior wear resistance. On the other hand, the Ti–Ti pair presents the worst combination in terms of tribological performance. While the Ti-TO pair performs better than the Ti– Ti pair tribologically, it is not as good as the TO-TO pair. It is essential to thermally oxidize both specimens in order to achieve optimal tribological performance. It is the oxide layer-on-oxide layer contact that imparts the excellent tribological performance. Failure of the oxide layer in one of the contact bodies can lead to high and unstable friction and increased wear from both contacting bodies. The tribological performance of the three contact pairs and the failure mechanism of the oxide layer are discussed in the paper. The results of this work suggest that the TO treated Ti on TO treated Ti contact pair would have potential tribological applications in engineering.Item Metadata only Improvement in Tribocorrosion Behaviour of 304 Stainless Steel by Surface Mechanical Attrition Treatment(Elsevier, 2014) Sun, Yong; Bailey, RichardThe tribocorrosion behavior of surface mechanical attrition treated (SMAT) AISI 304 stainless steel by spherical shot peening has been investigated under combined electrochemical and unidirectional sliding conditions in 0.9% NaCl solution. Sliding wear tests of both treated and untreated specimens were conducted under potentiodynamic, open circuit and potentiostatic conditions. It was found that under all test conditions, SMAT was effective in reducing material removal by 2 to 4 times and reducing coefficient of friction against an alumina slider. Detailed analysis showed that SMAT was effective in reducing both mechanical wear and chemical wear during tribocorrosion. The much improved tribocorrosion behavior can be attributed to the surface hardening effect of the surface layer induced by surface mechanical attrition treatment.Item Open Access An Investigation into the Effects of Process Conditions on the Tribological Performance of Pack Carburized Titanium with Limited Oxygen Diffusion(Springer, 2018-04-26) Bailey, Richard; Sun, YongIn the present study, a new pack carburization technique for titanium has been investigated. The aim of this treatment is to produce a titanium carbide/oxycarbide layer atop of an extended oxygen diffusion zone [α-Ti(O)]. The effects of treatment temperature and pack composition have been investigated in order to determine the optimal conditions required to grant the best tribological response. The resulting structural features were investigated with particular interest in the carbon and oxygen concentrations across the samples cross section. The optimization showed that a temperature of 925 °C with a pack composition of 1 part carbon to 1 part energizer produced surface capable of withstanding a contact pressure of ≈ 1.5 GPa for 1 h. The process resulted in TiC surface structure which offers enhanced hardness (2100 HV) and generates a low friction coefficient (μ ≈ 0.2) when in dry sliding contact with an alumina (Al O ) ball.Item Metadata only Pack carburisation of commercially pure titanium with limited oxygen diffusion for improved tribological properties(Elsevier, 2015) Bailey, Richard; Sun, YongIn the present work a new pack carburising surface treatment method has been developed, whereby oxygen diffusion and carburization of commercially pure titanium was undertaken. Pack carburization was carried out with a limited amount of oxygen, at a temperature of 925 oC for 20 hours. The carburising process resulted in a multilayer structure comprising a titanium carbide (TiC) network layer atop of a relatively thick α-titanium oxygen diffusion zone (α-Ti(O)). Initial tribological tests demonstrated that the new surface treatment can significantly enhance the tribological properties of titanium, in terms of much reduced friction, improved wear resistance and enhanced load bearing capacity. The TiC surface structure offers enhanced hardness (2100 HV) and low friction coefficient (µ ≈ 0.2) when in dry sliding contact with an alumina (Al2O3) ball, while the thick oxygen diffusion zone offers much enhanced load bearing capacity. When compared with untreated Ti, thermally oxidised titanium (TO-Ti) and hardened AISI 440C stainless steel, the carburized titanium allowed for a greatly improved friction and wear response.Item Metadata only The probation service as part of NOMS in England and Wales: fit for purpose?(Cullompton, Willan, 2007) Knight, C. H.; Bailey, Richard; Williams, BrianItem Open Access Surface Engineered Titanium for Improved Tribological, Electrochemical and Tribo-electrochmical Performance(De Montfort University, 2015) Bailey, RichardIn the present study, efforts have been made to produce protective surface layers in order to improve the tribological, electrochemical and tribo-electrochemical response of titanium. In order to achieve this, two different techniques were employed: 1) thermal oxidation (TO) and 2) pack carburisation with oxygen diffusion (PC). Thermal oxidation of commercially pure titanium (CP-Ti) was undertaken at a temperature of 625 °C for durations of 5, 20 and 72 h. This results in a multi-layered structure comprising a titanium dioxide layer (rutile) atop of an α-titanium oxygen diffusion zone (α-Ti(O)). Initial attempts have also been made to improve the frictional behaviour of the oxide layer, using a prior surface mechanical attrition treatment (SMAT) and controlled slow cooling after oxidation. The results demonstrate that these prior and post treatments have a positive effect on the tribological performance of the oxide layer. Electrochemical and tribo-electrochemical characterisation was also carried out in a 0.9% NaCl solution. Electrochemical tests provided evidence that oxygen content in the upper part of the oxygen diffusion zone (depths < 5 μm from the surface) helps to accelerate passive film formation and thus improve the corrosion resistance of CP-Ti. Tribo-electrochemical testing of TO-Ti was carried out against an alumina counter face under various anodic and cathodic potentials. It is shown that the rutile oxide layer offers low friction and improved wear resistance. An unusual anodic protection behaviour for the oxide film has also been observed. When the TO-Ti is polarised anodically during sliding, the durability of the oxide layer is prolonged, resulting in low friction and much reduced material loss. In the present work a new pack carburising surface treatment method has been developed, whereby oxygen diffusion and carburisation of CP-Ti were undertaken concurrently. Optimisation of the process showed that a temperature of 925 °C for 20 h resulted in a multilayer structure comprising of a titanium carbide (TiC) network layer atop of a relatively thick α-Ti(O) diffusion zone. Tribological testing demonstrated that the new surface treatment can significantly enhance the tribological properties of titanium, in terms of much reduced friction (μ ≈ 0.2), improved wear resistance and enhanced load bearing capacity. Electrochemical corrosion testing also showed the PC-Ti retained the favourable corrosion characteristics of CP-Ti. Tribocorrosive testing revealed an improved tribological response when compared with that of untreated CP-Ti.Item Open Access Surface finish and properties enhancement of selective laser melted 316L stainless steel by surface mechanical attrition treatment(Elsevier, 2019-10-31) Sun, Yong; Bailey, Richard; Moroz, AdamSelective laser melting (SLM) has been used to produce stainless steel components with nearly full density, targeting real engineering applications. However, materials processed by SLM suffer from an inherent problem of poor surface finish, which is not suitable for many practical applications. It is thus necessary to improve the surface finish and surface integrity of SLM components through post processing. The aim of this work is to improve the surface finish of SLM 316L stainless steel by surface mechanical attrition treatment (SMAT), which involves bombarding the SLM sample surface with steel balls at a vibration frequency of 40 Hz for 10 min to 80 min. The surface finish, morphology, hardness and unlubricated sliding friction and wear behaviour were investigated. The results show that SMAT is very effective in smoothing the SLM 316L surface, reducing the surface roughness by up to 96% and achieving a surface finish comparable to that produced by surface grinding. SMAT also has the added benefits of increasing surface hardness, reducing friction and improving dry sliding wear resistance of SLM 316 L stainless steel.Item Open Access Tribocorrosion Response of Surface-Modified Ti in a 0.9% NaCl Solution(MDPI, 2018-09-25) Bailey, RichardTitanium use is limited due to its poor tribological properties, and thermal oxidation (TO) and pack carburisation with limited oxygen diffusion (PCOD) are just two of the surface treatments that can be used to enhance the surface properties of Ti. In this study, commercially pure titanium was surface modified using thermal oxidation (TO) and pack carburisation with limited oxygen diffusion (PCOD). Samples were tribological tested in a 0.9% NaCl solution under a contact load of 20 N to investigate the mechanical and electrochemical response of the surface treatments. The tests conducted show that a clear benefit can be obtained in terms of the overall material loss rate using both TO and PCOD. The TO and PCOD treatments generate very different surface structures: TO produces a rutile TiO2 surface film and the PCOD treatment produces a TiC network structure. Both treatments improve the load bearing capacity with the assistance of an oxygen diffusion zone (ODZ). When subjected to sliding contact in a 0.9% NaCl solution, the results show the PCOD-Ti produced the best overall results, with a material loss rate 7.5 times lower than untreated Ti and 2.4 times lower than TO-Ti. The improved wear rate of the PCOD-Ti is attributed to the TiC network structure. The TO-Ti suffers from rapid film failure and high friction. The reduced material loss rate (MLR) of the TO-Ti is attributed to the hard wearing ODZ.Item Metadata only Unlubricated sliding friction and wear characteristics of thermally oxidized commercially pure titanium(Elsevier, 2013) Bailey, Richard; Sun, Yong