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TiB2+TiB coatings were formed on Ti–6Al–4V through a molten-salt diffusional process at temperatures of 850 °C and 900 °C for 16 h. The thickness of the TiB layer increased by about two times at the higher process temperature, while the thickness of the TiB2 layer remained constant. Tribocorrosion rate of Ti–6Al–4V and the coated samples was evaluated in a reciprocating sliding under a normal load of 15 N in a phosphate buffer saline (PBS) solution for 3600–36000 cycles against an alumina ball. The results showed that the tribocorrosion rate of the borided samples decreased up to 56 times compared with Ti–6Al–4V after 36000 cycles. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies showed the presence of oxide-rich patches on the wear surface of Ti–6Al–4V with a thickness of up to 1 μm. TEM and atomic force microscopy (AFM) images also revealed the presence of a tribofilm with a thickness of up to 200 nm on the surface of the boride coating. In addition, X-ray photoelectron spectroscopy (XPS) analysis confirmed the tribofilm formed on the wear surface of coated samples contained B2O3/H3BO3 compound, resulting in a more stable fluctuation in coefficient of friction and open circuit potential during sliding. The SEM images of the alumina wear surface showed cracks and titanium transfer layers in contact with the borided layers and Ti–6Al–4V, respectively.

In this study, PEO coatings were produced on AZ91 Mg alloy using pulsed waveforms at different electrical parameters such as type (unipolar and bipolar), cathodic duty cycle (20 and 40 %), and voltage amplitude (350 and 400 V) to assess wear and tribocorrosion resistance. The coating bath contained NaAl2O4 and NaF. The coating phase composition, microstructure, and chemical composition of the coatings were evaluated using GXRD, SEM, and EDS. Dry wear behavior was studied using the reciprocating ball-on-flat device, while tribocorrosion behavior was evaluated by immersing the coated specimens in 3.5 wt% NaCl solution and reading the OCP before, during, and after sliding. The worn area in both cases was also examined. The results showed that the bipolar waveform with the higher cathodic duty cycle (40 %) provided the best tribocorrosion and wear performance by forming MgF2 (as a corrosion-resistant phase) and MgAl2O4 (as a hard phase). At all three waveforms, the higher coating voltage (i.e. 400 V) enhanced the wear and tribocorrosion resistance by forming thicker coatings with higher amounts of MgF2 and MgAl2O4 phases.

Tribocorrosion, a research field that has been evolving for decades, has gained renewed attention in recent years, driven by increased demand for wear- and corrosion-resistant materials from biomedical implants, nuclear power generation, advanced manufacturing, batteries, marine and offshore industries, etc. In the United States, wear and corrosion are estimated to cost nearly USD 300 billion per year. Among various important structural materials, passive metals such as aluminum alloys are most vulnerable to tribocorrosion due to the wear-accelerated corrosion as a result of passive film removal. Thus, designing aluminum alloys with better tribocorrosion performance is of both scientific and practical importance. This article reviews five decades of research on the tribocorrosion of aluminum alloys, from experimental to computational studies. Special focus is placed on two aspects: (1) The effects of alloying and grain size on the fundamental wear, corrosion, and tribocorrosion mechanisms; and (2) Alloy design strategies to improve the tribocorrosion resistance of aluminum alloys. Finally, the paper sheds light on the current challenges faced and outlines a few future research directions in the field of tribocorrosion of aluminum alloys.

Majority of self-lubricating composites exhibit a high wear rate due to corrosion. In this study, Co-based self-lubricating composites with addition of Ag were prepared via spark plasma sintering to manage their tribocorrosion resistance. No interfacial reaction occurred after sintering. Their tribocorrosion behavior in 3.5 wt.% NaCl solution was characterized as a function of applied potentials. In corrosion-free conditions, i.e. applying a cathodic potential (−1 V), the addition of Ag enhances wear rate of the Co-based composites. While in a state of OCP or applying an anodic potential, galvanic corrosion occurs between Ag and Co-matrix. It promotes the formation of a loose oxide film and reserves most silver debris, which contributes synergistically to reduced friction coefficient and wear rate. With the addition of 12 wt.% Ag, Co-based self-lubricating composite exhibits the lowest friction coefficient of 0.09 and wear rate of 3.8 × 10−5 mm3/(Nm) at OCP.

Titanium dioxide nanotubes (TNTs) have been extensively researched for their enhanced biomedical characteristics, including biocompatibility, cell apposition, and growth morphology. However, there is a significant concern in metallic medical devices owing to micro-movements between implants and bone in aggressive environments due to wear and corrosion synergies, leading to adverse body responses and implant failure. In this study, TNTs on Commercially Pure titanium (C.P. Ti) with three different thickness layers were grown to correlate their corrosion and wear behavior. Initially amorphous after anodization, TNTs underwent annealing at 450 °C for 2 h to transform the distorted, into a crystalline structure. The characterization included X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX), X-ray Photoelectron Spectroscopy (XPS), and contact profilometry. Potentiodynamic polarization (PD) and tribocorrosion tests were conducted in Simulated Body Fluid Electrolyte (SBF). SEM micrographs showed TNT thickness layers of 314, 691, and 5280 nm, and X-ray Diffraction showed anatase transformation post-annealing. Results confirmed a significant influence of TNT thickness layers on corrosion and tribocorrosion properties, with higher current density obtained from PD for thicker TNTs layers, associated with surface fluorine content. During tribocorrosion, annealed samples demonstrated lower corrosion tendency, potential drop, and coefficient of friction. Morphology of worn surfaces and volumetric wear rate varied with TNT thickness layer and thermal treatment.

Additive manufactured Ti6Al4V has shown high tensile anisotropy. The tribocorrosion properties involve the coupling of mechanical wear and surface corrosion, and its anisotropy is unclear. In this study, the corrosion resistance of the horizontal (XOY) plane and the vertical (V) plane was compared by electrochemical tests. The wear resistance and tribocorrosion resistance of different planes of laser powder bed fusion (L-PBF) Ti6Al4V were tested by using zirconia ball as friction pair. The results show that the corrosion resistance of the V plane was better than that of the XOY plane. However, the wear and tribocorrosion resistance recorded for the XOY plane was better than that of the V plane. The columnar crystals along the building direction led to the anisotropy of wear and tribocorrosion of L-PBF Ti6Al4V.

The combined corrosion and wear behaviour of NiTiNOL60 alloy is important in various engineering applications. While previous studies have explored its performance in artificial seawater environments, limited information exists regarding its tribocorrosion characteristics in acidic conditions. This paper investigates the synergistic interaction between sliding wear and electrochemical processes for NiTiNOL60 alloy in a sulfuric acid environment, employing experimental procedures compliant with ASTM standards. Microscopic analysis confirms the alloy's Ni-rich composition, featuring a dense network of B2 NiTi + Ni4Ti3 cubic and rhombohedral crystal matrix structures. Our research and results reveal that material degradation during tribocorrosion arises from the combined effects of sliding wear and electrochemical reactions. Consequently, multiple wear mechanisms influenced by tribochemical wear are observed, with delamination and micro-cracks being notably prominent under higher applied loads due to surface tensile stress and contact pressure, leading to crack propagation perpendicular to the sliding direction. These findings have practical implications for optimising the performance and durability of NiTiNOL60 alloy in acidic environments, offering valuable insights for load-bearing engineering applications.

High levels of cobalt and chromium ions were detected in the bodies of multiple recipients of modular cobalt chrome molybdenum metal-on-metal hip implants, necessitating the revision of their implants. A forensic engineering investigation of provided discovery documents and existing literature regarding the design, manufacturing, and clinical testing of these modular hip implants was performed. The investigation revealed that the modular interfaces of the implant allowed for micromotion to induce mechanically assisted crevice corrosion at these surfaces. The debris from this corrosion resulted in the release of metal ions into the bodies of the users, forming pseudotumors and compromising the user's health and wellbeing. The effect of this corrosion was enhanced by the galvanic couple that existed between the modular components of the implant. In addition, scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS) analysis identified silicon carbide (SiC) and aluminum oxide (AL2O3) particles left behind from polishing, which were embedded in the ball and liners. These particles accelerated the wear of the hip implant and further exacerbated the release of metal ions. The designers of future hip implants should take care in preventing the occurrence of the above-stated factors. [ABSTRACT FROM AUTHOR]

Electroless nickel-boron coatings present outstanding properties such as high hardness, excellent wear resistance and uniform coating, and thus they are considered to be alternative to toxic hard chrome coatings. However, they contain lead that is toxic and used as stabilizer in the plating bath. This study aims to investigate the tribocorrosion behaviour of lead-free electroless nickel-boron coatings. In the present research, several tests were carried out to investigate the behaviour of these coatings under both dry and tribocorrosion reciprocating sliding wear against alumina balls, at room temperature. The open circuit potential (OCP) method was used to determine the degradation mechanism of the coatings. The results of the tribocorrosion and dry wear tests showed that the performance of coatings was very different from each other. A steady state for the coefficient of friction (COF) is achieved during the tribocorrosion test, whereas the constant production of debris and their presence in the contact implied an increase in COF with distance during the dry wear test. The wear mechanisms of these coatings also presented variations in these tests. It was found that the wear area calculated from tribocorrosion is lower (56 µm2) than the one from dry sliding test (86 µm2). [ABSTRACT FROM AUTHOR]

Impact-sliding caused by random vibrations between tubes and supports can affect the operation of heat exchangers. In addition, a corrosive environment can cause damage, accelerating the synergism of corrosion and wear. Therefore, the focus of this work was the impact-sliding fretting tribocorrosion behavior of 316L heat exchanger tubes at different halide concentrations. A device system incorporating the in situ electrochemical measurements of impact-sliding fretting corrosion wear was constructed, and experiments on 316L heat exchanger tubes in sodium chloride (NaCl) solution with different concentrations (0.0, 0.1, 0.5, 1.0, 3.5, and 5.0 wt%) were carried out. The synergism between wear and corrosion was also calculated and analyzed. The wear and damage mechanisms were elucidated by correlating the corrosion-wear synergism, morphologies, and material loss rates. The results indicated that the stable wear stage occurred at approximately 9–12 h, after which the corrosion current increased with the expansion of the wear area. As the halide concentration increased, the scale of damage on the wear scars gradually decreased, changing from being dominated by cracks, delaminations, and grooves to being dominated by scratches, microgrooves, and holes. There was an obvious positive synergism between wear and corrosion. The material loss was dominated by pure mechanical wear and wear enhanced by corrosion, but corrosion enhanced by wear contributed more than tangential sliding fretting corrosion. The total mass loss increased gradually in the range of 0.0–0.5 wt% and decreased in the range of 0.5–5.0 wt%. Large-scale damage enhanced by corrosivity and small-scale damage reduced by lubricity dominated the material loss at low and high concentrations, respectively. [ABSTRACT FROM AUTHOR]

When introduced into the body, the implant interacts with biological environment and may suffer corrosion. In addition, when this implant is submitted to friction, it may degrade by tribocorrosion due to the simultaneous action of corrosion by the body liquid and mechanical wear. Both corrosion and tribocorrosion are connected to the presence of proteins that cover the surface implant. The latter plays an ambiguous role on corrosion since dozens of contradictory papers pointed out their beneficial or detrimental effect. After its introduction into the body, the implant should form a direct interface with bone through structural and functional connection. The osseointegration and the strength of interfacial bond depend on surface properties of the implant, namely, its topographical and physico-chemical properties. In addition, since bone cells are sensitive to the species produced during the implant corrosion, when corrosion occurs, this may lead to impact osseointegration and to cause implant loosening. There is a strong connection between corrosion and osseointegration, both of which are worth discussion. That is the object of the present narrative review where we will discuss: (1) corrosion and tribocorrosion of titanium alloys used as biomaterials paying particular attention to the influence of proteins, (2) the effect of implant roughness and surface energy on osseointegration. [ABSTRACT FROM AUTHOR]

Tribocorrosion, a research field that has been evolving for decades, has gained renewed attention in recent years, driven by increased demand for wear- and corrosion-resistant materials from biomedical implants, nuclear power generation, advanced manufacturing, batteries, marine and offshore industries, etc. In the United States, wear and corrosion are estimated to cost nearly USD 300 billion per year. Among various important structural materials, passive metals such as aluminum alloys are most vulnerable to tribocorrosion due to the wear-accelerated corrosion as a result of passive film removal. Thus, designing aluminum alloys with better tribocorrosion performance is of both scientific and practical importance. This article reviews five decades of research on the tribocorrosion of aluminum alloys, from experimental to computational studies. Special focus is placed on two aspects: (1) The effects of alloying and grain size on the fundamental wear, corrosion, and tribocorrosion mechanisms; and (2) Alloy design strategies to improve the tribocorrosion resistance of aluminum alloys. Finally, the paper sheds light on the current challenges faced and outlines a few future research directions in the field of tribocorrosion of aluminum alloys. [ABSTRACT FROM AUTHOR]

The interaction of different dental alloys with the oral environment may cause severe side effects (e.g., burning sensation, inflammatory reactions, carcinogenesis) as a result of oral galvanism. However, the pathogenesis of side effects associated with oral galvanism is still unclear, and the effects of direct current and alloy corrosion ions are considered potentially contributing factors. Therefore, the aim of this study was to systemically compare the damaging effects of (1) galvanism as a synergistic process (direct current + corrosion ions), (2) direct current separately, and (3) corrosion ions separately on an in vitro mucosa-like model based on a cell line of immortalized human keratinocytes (HaCaTs) to reveal the factors playing a pivotal role in dental alloys side effects. For this, we chose and compared the dental alloys with the highest risk of oral galvanism: Ti64–AgPd and NiCr–AgPd. We showed that galvanic current may be the leading damaging factor in the cytotoxic processes associated with galvanic coupling of metallic intraoral appliances in the oral cavity, especially in the short-term period (28 days). However, the contribution of corrosion ions (Ni2+) to the synergistic toxicity was also shown, and quite possibly, in the long term, it could be no less dangerous. [ABSTRACT FROM AUTHOR]

The tribocorrosion property of tungsten plays a great role in the chemical mechanical polishing of tungsten plugs used in integrated circuits. This study applied a lubricated tribocorrosion model to tungsten, verified and calibrated the model using results from laboratory tribocorrosion experiments, and predicted the effect of the key parameters on the mechanical and chemical wear behavior of tungsten. The results showed that the model could be successfully applied to the tribocorrosion of tungsten considering that the prevailing wear mechanism and the electrochemical corrosion property of tungsten fulfills the model's basic concepts. The model was able to predict the influence of the material, mechanical, electrochemical and rheological parameters on the mechanical wear and chemical wear behavior of tungsten. The model could clearly distinguish the contribution of the mechanical wear and chemical wear to the total wear degradation of tungsten, which provides useful instructions on how to control the related parameters in order to obtain tailored removal rate and surface quality in tungsten's chemical mechanical polishing process. [ABSTRACT FROM AUTHOR]

Abstract Impact-sliding caused by random vibrations between tubes and supports can affect the operation of heat exchangers. In addition, a corrosive environment can cause damage, accelerating the synergism of corrosion and wear. Therefore, the focus of this work was the impact-sliding fretting tribocorrosion behavior of 316L heat exchanger tubes at different halide concentrations. A device system incorporating the in situ electrochemical measurements of impact-sliding fretting corrosion wear was constructed, and experiments on 316L heat exchanger tubes in sodium chloride (NaCl) solution with different concentrations (0.0, 0.1, 0.5, 1.0, 3.5, and 5.0 wt%) were carried out. The synergism between wear and corrosion was also calculated and analyzed. The wear and damage mechanisms were elucidated by correlating the corrosion-wear synergism, morphologies, and material loss rates. The results indicated that the stable wear stage occurred at approximately 9–12 h, after which the corrosion current increased with the expansion of the wear area. As the halide concentration increased, the scale of damage on the wear scars gradually decreased, changing from being dominated by cracks, delaminations, and grooves to being dominated by scratches, microgrooves, and holes. There was an obvious positive synergism between wear and corrosion. The material loss was dominated by pure mechanical wear and wear enhanced by corrosion, but corrosion enhanced by wear contributed more than tangential sliding fretting corrosion. The total mass loss increased gradually in the range of 0.0–0.5 wt% and decreased in the range of 0.5–5.0 wt%. Large-scale damage enhanced by corrosivity and small-scale damage reduced by lubricity dominated the material loss at low and high concentrations, respectively.

Ferritic stainless steels armored with borides had their endurance tested in demanding both abrasive and corrosive environment. The degradation was investigated through a very aggressive plate-on-cylinder wear test in water-based drilling mud containing chlorides, which was designed to simulate, in laboratorial scale, the corrosive tribosystem found in the wear of risers and casings used in deep water oil exploitation. A commercially-grade 430 ferritic stainless steel containing boron content far beyond its solubility limity, namely 1.2 and 3.5 wt.%, was processed by spray-forming to induce a ferritic stainless steel matrix protected by a boride skeleton. Additional corrosion assessment was performed by potentiodynamic polarization and electrochemical impedance spectroscopy in 0.27 M KCl solution, since KCl is a common clay swelling inhibitor. For comparison, API 5L X80 steel was also included since this material is used in risers and casings manufacture. The addition of boron (1.2 and 3.5 wt.%) led to the formation of microstructures composed of an α-ferrite matrix with homogeneously distributed M2B-type borides of different morphologies. Electrochemical tests revealed high corrosion resistance of the alloy with 1.2 wt.% B. However, the alloy with 3.5 wt.% B showed a considerable decrease in corrosion resistance due to Cr-depletion of the ferritic matrix given the M2B formation richer in Cr. Therefore, the alloy with 1.2 wt.% B offered the best tribocorrosion resistance.

Ti6Al4V alloy has good corrosion resistance due to the formation of the passive oxide films on the surface of Ti6Al4V alloy. However, Ti6Al4V alloy has poor tribocorrosion resistance in the seawater environment. Herein the present work, plasma electrolytic oxidation (PEO) with the electrolyte of glycerol and sodium borate is used to generate PEO coatings on the surface of Ti6Al4V alloy to improve its tribocorrosion properties. The microstructure and tribocorrosion properties of PEO coatings are investigated by using scanning electron microscopy, X‐ray diffraction, and tribometer, respectively. The growth kinetics and the tribocorrosion mechanisms of PEO coatings are discussed in detail. It is shown in the results that PEO coatings deposited on the surface of Ti6Al4V alloy are composed of rutile and anatase phases. The surface hardness and thickness of PEO coatings are enhanced with the increase of the voltage and time. The wear rate of Ti6Al4V alloy with PEO coatings is significantly reduced in artificial seawater. [ABSTRACT FROM AUTHOR]

Stainless steel (SS316L) and titanium alloy (Ti6Al4V) exhibit suitable properties for biomedical applications; however, the tribocorrosion of these materials, which is associated with metallosis, is still a significant concern. This work investigates the effectiveness of DLC smoothing coatings applied to the metals to reduce tribocorrosion and improve cell viability. The study was motivated by many reports of metallosis caused by metal debris in the soft tissues of the body. DLC coatings were produced using the plasma-enhanced chemical vapor deposition (PECVD) technique. The cytotoxicity, genotoxicity, and cell viability of metallic samples with and without DLC coatings were analyzed, considering the chemical composition of the coating and metallic components. The results show that the DLC coatings presented suitable interaction properties and no cytotoxicity or genotoxicity when exposed to the cellular environment, compared with the control group (p < 0.0001). They also demonstrated cell viability, low friction representing a reduction of 80%, and hardness 23–26 GPa, making them ideal for use on fixed implants. It is necessary to control the thickness and roughness of the coating to avoid pinholes and increase the corrosion protection of implants. These DLC coatings with low friction coefficients could facilitate the fixation of implantable pins and screws, including Kirschner wires. [ABSTRACT FROM AUTHOR]

To reveal the influence of passive film on the tribocorrosion behaviour of stainless steel, SUS430 was loaded at 2.0 N or 10.0 N in aqueous solutions with various pH from 1.0 to 10.0. The pure wear behaviour was investigated in the air for comparison. The polarization behaviour, the morphology of the worn or tribocorroded surface, and the depth profiles of the formed groove were measured to discuss the mechanism. The passive state was confirmed at pH = 7.0 and 10.0, but vanished at pH = 1.0 and 2.0. The pure wear in air depended on the applied loads, rather than the sliding time. On the other hand, the tribocorrosion in deionised water was much smaller than the pure wear in air. Under a load of 2.0 N, the tribocorrosion at pH = 1.0 was weaker than pH = 2.0. However, the situation reversed when increasing the load to 10.0 N. The tribocorrosion in neutral and alkaline solutions is considerably smaller than in acid solutions. [ABSTRACT FROM AUTHOR]

AlCrTiZrMo high-entropy alloy (HEA) films with strong amorphization were obtained by co-filter cathode vacuum arc deposition, and the effect of thermal shock on the films was investigated in order to explore the protection mechanism of HEA films against mechanical components in extreme service environments. The results show that after annealing at 800 °C for 1 h, the formation of a dense ZrTiO4 composite oxide layer on the surface actively prevents the oxidation from continuing, so that the AlCrTiZrMo HEA film exhibits excellent oxidation resistance at 800 °C in air. In the friction-corrosion coupling environment, the AlCrTiZrMo HEA film annealed at 800 °C for 1 h shows the best tribocorrosion resistance due to the stable dense microstructure and excellent mechanical properties, and its ΔOCP, COF and wear rate possess the smallest values of 0.055, 0.04 and 1.34 × 10−6 mm−3·N−1·m−1. [ABSTRACT FROM AUTHOR]

The challenge of concurrently resisting corrosion, wear, and microbial adhesion in marine equipment necessitates the development of advanced protective coatings for moving parts. Leveraging the unique properties of constituent phases in nanocomposite materials offers a promising approach. Here, we report the development of a high-performance protective coating material combining hard, anti-corrosive, and antifouling TaB 2 phase with a self-lubricating amorphous carbon (a-C) phase. The synthesized specimens form an "a-C embedded in TaCB solid solution" (a-C/TaCB) structure at 8 at.% carbon content and transition to a "TaCB solid solution embedded in a-C" (TaCB/a-C) structure at 18.8 at.% carbon content. The a-C/TaCB coating demonstrates enhanced tribological, corrosion and tribocorrosion performances compared to the TaB 2 coating, while maintaining excellent mechanical and antifouling performances without the usual deterioration caused by an excess soft biocompatible a-C phase. The rational design of this dual-phase nanocomposite structure could facilitate the development of a unique class of protective coating materials tailored to meet the stringent requirements of harsh marine environments. [ABSTRACT FROM AUTHOR]

This works proposes a methodology for fabricating materials with specific characteristics mimicking human bones. A Ti64 alloy powder was used as the base material and it was mixed with Ag, Ta, TiN and salt particles to obtain different features. A hip-bone like component was fabricated, including a highly porous core of Ti64/25Ta/5Ag and a compact outer shell of Ti64/5Ag that is supposed to improve corrosion and osseointegration. Besides, a harder cover surface in Ti64/10TiN composite should increase the wear resistance. The green component was sintered at 1260°C in argon. Its Young's modulus was close to the one of bones due to the added porosity, which also provided a permeability close to the one reported for trabecular bones. Tribocorrosion behaviour in simulated body fluid was improved by TiN addition. In conclusion, the proposed processing route was able to produce complex components fulfilling specific features required for human bone replacement. [ABSTRACT FROM AUTHOR]

High-nitrogen stainless steels, which are developed by replacing nickel with nitrogen, have been widely applied in manufacturing wear parts in mechanical engineering. In this study, the tribocorrosion performance of a ferritic high-nitrogen bearing stainless steel (40Cr15Mo2VN) under acetic acid solution with a pH of 3.0 was investigated under different loads ranging from 25 N to 125 N. Quantitative calculations indicated that pure mechanical wear was the predominant cause of material degradation, while the corrosion-accelerated wear component also played a crucial role. The material loss induced by both tribocorrosion and mechanical wear increased with increasing load, leading to severe delamination at sliding surfaces and larger wear debris. [ABSTRACT FROM AUTHOR]

The urgent need for drastic reduction in emissions due to global warming demands a radical energy transition in transportation. The role of biofuels is fundamental to bridging the current situation towards a clean and sustainable future. In passenger cars, the use of ethanol fuel reduces gas emissions (CO2 and other harmful gases), but can bring tribological challenges to the engine. This review addresses the current state-of-the-art on the effects of ethanol fuel on friction, lubrication, and wear in car engines, and identifies knowledge gaps and trends in lubricants for ethanol-fuelled engines. This review shows that ethanol affects friction and wear in many ways, for example, by reducing lubricant viscosity, which on the one hand can reduce shear losses under full film lubrication, but on the other can increase asperity contact under mixed lubrication. Therefore, ethanol can either reduce or increase engine friction depending on the driving conditions, engine temperature, amount of diluted ethanol in the lubricant, lubricant type, etc. Ethanol increases corrosion and affects tribocorrosion, with significant effects on engine wear. Moreover, ethanol strongly interacts with the lubricant's additives, affecting friction and wear under boundary lubrication conditions. Regarding the anti-wear additive ZDDP, ethanol leads to thinner tribofilms with modified chemical structure, in particular shorter phosphates and increased amount of iron sulphides and oxides, thereby reducing their anti-wear protection. Tribofilms formed from Mo-DTC friction modifier are affected as well, compromising the formation of low-friction MoS2 tribofilms; however, ethanol is beneficial for the tribological behaviour of organic friction modifiers. Although the oil industry has implemented small changes in oil formulation to ensure the proper operation of ethanol-fuelled engines, there is a lack of research aiming to optimize lubricant formulation to maximize ethanol-fuelled engine performance. The findings of this review should shed light towards improved oil formulation as well as on the selection of materials and surface engineering techniques to mitigate the most pressing problems. [ABSTRACT FROM AUTHOR]

Nitriding has long been used to engineer the surfaces of engineering steels to improve their surface and subsurface properties. The role of the surface compound layer (γ′-Fe4N and/or ε-Fe2-3N) in improving the tribological and corrosion-resistant properties of nitrided steels has been established. However, there have been very few studies on the response of the compound layer to tribocorrosion in corrosive environments. In this work, the tribocorrosion behavior of a 5 μm thick γ′-Fe4N nitride layer produced on mild steel (MS) by plasma nitriding has been studied in a NaCl-containing solution under various electrochemical conditions. The results show that at a cathodic potential of −700 mV (saturated calomel electrode, SCE), where mechanical wear is predominant, the total material removal (TMR) from the γ′-Fe4N layer is 37% smaller than that from the untreated MS, and at open circuit potential, TMR from the layer is 34% smaller than that from the untreated MS, while at an anodic potential of −200 (SCE), the γ′-Fe4N layer can reduce TMR from mild steel by 87%. The beneficial effect of the γ′-Fe4N nitride layer in improving the tribocorrosion behavior of mild steel is derived from its high hardness and good corrosion resistance in the test solution and its ability to resist both mechanical wear and corrosion and to reduce wear–corrosion synergism. [ABSTRACT FROM AUTHOR]

In this paper, a multi-functional composite coating with low friction coefficient, high wear resistance and excellent tribocorrosion resistance is fabricated on AZ31 Mg alloys by micro-arc oxidation and spray-coating methods. The microstructure, and composition of the coating are characterized by SEM, EDS, XRD, and FT-IR. Potentiodynamic polarization and EIS tests are conducted to evaluate the corrosion resistance of the composite coating. The tribocorrosion property is also studied using pin-on-disk tribometer in 3.5 wt.% NaCl solution. It is found that the composite coating possesses better long-term corrosion resistance than the single MAO coating. The tribocorrosion tests prove that the composite coating exhibits much better wear and tribocorrosion resistance than the single MAO coating and can protect the substrate from corrosion under a sliding condition.

Tribocorrosion of titanium alloys improves by thermal oxidation which results in formation of an oxygen diffusion layer (ODL). However, the formation of ODL decreases the biocompatibility of titanium. The main goal of this paper was to remove this drawback by generation of a more bio-active layer of porous anodic oxide on ODL. Effects of normal load and sliding distance on the tribocorrosion behavior of anodic oxide layers produced by an anodizing process on an ODL were investigated. The ODL layer was formed on CP-Ti by thermal oxidation process in an atmospheric furnace at 850 °C followed by the anodizing process performed at voltages of 150 and 175 V in sulfuric acid solution. Cell viability tests revealed higher biocompatibility for the anodized samples compared to the ODL and titanium. Tribocorrosion tests were carried out under normal loads of 0.5, 1 and 1.5 N at sliding distances of 5–300 m in a phosphate saline buffer solution (PBS) using a pin-on-disk tribometer. The results showed that the anodized layers were durable enough to resist tribological stresses at sliding distances of 5 and 25 m. Further increase in the sliding distance, however, resulted in local damages on the oxide layers followed by a complete removal at a sliding distance of 300 m, especially under the high normal loads of 1 and 1.5 N. The ODL showed the lowest tribocorrosion rate followed by the sample anodized at 150 V and 175 V. Highest hardness and elastic modulus were obtained for the ODL using nano-indentation tests.

Titanium is the most commonly used material for the production of implants,but titanium dental implants are not immune to corrosion due to the complex oral cavity environments.The concentration of titanium ions increases in tissues around the implants due to the corrosion,leading to allergic reactions and inflammation,which hinder the long-term safe service of implants.In this paper,the research progress on corrosion of titanium implants was reviewed based on different types of influencing factors,including corrosion due to the effect of inorganics and organics,corrosion due to microorganisms and tribocorrosion.Besides,the future research was prospected.

This research was carried out with the aim of obtaining appropriate principles for describing the influence of working parameters and the aggressive action of an acidic medium on the wear and corrosion resistance of martensitic stainless steels. Tribological tests were performed on induction-hardened surfaces of stainless steels X20Cr13 and X17CrNi16-2 under combined wear conditions at a load of 100 to 300 N and a rotation speed of 382 to 754 min−1. The wear test was carried out on a tribometer with the use of an aggressive medium in the chamber. After each wear cycle on the tribometer, the samples were exposed to corrosion action in a corrosion test bath. Analysis of variance revealed a significant influence of rotation speed and load due to wear on the tribometer. Testing the difference in the mass loss values of the samples due to corrosion using the Mann–Whitney U test did not show a significant effect of corrosion. Steel X20Cr13 showed greater resistance to combined wear, which had a 27% lower wear intensity compared to steel X17CrNi16-2. The increase in wear resistance of X20Cr13 steel can be attributed to the higher surface hardness achieved and the effective depth of hardening. The mentioned resistance is the result of the creation of a martensitic surface layer with dispersed carbides, which increases the resistance to abrasion, dynamic durability, and fatigue of the surface of the protective layer. [ABSTRACT FROM AUTHOR]

An enhanced understanding of the interaction of wear and corrosion interaction of type 304L SS in various nitric acid concentrations is essential to avoid any failure of the component in a nuclear reprocessing plant. Therefore, the present work is focused on investigating the tribocorrosion behaviour and mechanism of type 304L stainless steel (SS) in different concentrations of 3, 6, 8, and 11.5 M nitric acid simulating a nuclear reprocessing environment. The open circuit potential sliding results revealed that the cathodic potential shift depends on the nitric acid concentrations. The intermittent sliding test demonstrated faster repassivation kinetics in the wear track between the successive sliding contacts as the increase in nitric acid concentration. At higher nitric acid concentration, the regeneration of oxide film in the contact region reduces friction and wear. Thus, the specific wear rate increases in the order of 11.5 < 8 < 6 < 3 M HNO3. The tribocorrosion material degradation mechanism of type 304L SS in nitric acid for nuclear reprocessing application is described. [ABSTRACT FROM AUTHOR]

The digital health industry is experiencing fast-paced research which can provide digital care programs and technologies to enhance the competence of healthcare delivery. Orthopedic literature also confirms the applicability of artificial intelligence (AI) and machine learning (ML) models to medical diagnosis and clinical decision-making. However, implant monitoring after primary surgery often happens with a wellness visit or when a patient complains about it. Neglecting implant design and other technical errors in this scenario, unmonitored circumstances, and lack of post-surgery monitoring may ultimately lead to the implant system's failure and leave us with the only option of high-risk revision surgery. Preventive maintenance seems to be a good choice to identify the onset of an irreversible prosthesis failure. Considering all these aspects for hip implant monitoring, this paper explores existing studies linking ML models and intelligent systems for hip implant diagnosis. This paper explores the feasibility of an alternative continuous monitoring technique for post-surgery implant monitoring backed by an in vitro ML case study. Tribocorrosion and acoustic emission (AE) data are considered based on their efficacy in determining irreversible alteration of implant material to prevent total failures. This study also facilitates the relevance of developing an artificially intelligent implant monitoring methodology that can function with daily patient activities and how it can influence the digital orthopedic diagnosis. AI-based non-invasive hip implant monitoring system enabling point-of-care testing [ABSTRACT FROM AUTHOR]

AZ31 alloy is a widely used material in biomedical applications. It is an alternative alloy for temporary implantation due to its low weight and superior biocompatibility. However, surface properties such as wear and corrosion are quite weak compared to other metallic biomaterials. It is extremely important to improve the surface properties, as these two mechanisms cause very serious material damage on Mg alloys separately or synergistically. In this context, oxidation processes are carried out with the plasma electrolytic oxidation (PEO) method, which provides very successful adhesion in alloys such as AZ31. In this study, the tribocorrosion performance of the films produced by doping Cu, B and Zn elements using PEO was investigated. The simultaneous effects of corrosion and wear mechanisms on surfaces were investigated with experiments carried out in artificial body fluid (SBF). It was concluded that the porous oxide films undergo morphological changes with the effect of additive elements, this change in morphology has a barrier effect, especially against corrosion attacks, and the improved corrosion resistance also improves the wear performance. According to the OCP measurements made under wear, the surface that showed the most noble behavior was Zn-doped (−0.71 V). A similar behavior can be mentioned for the wear test carried out together with the potentiodynamic polarization test. It minimized the Zn current density value in the structure (2.3 × 10−6 A/cm2). [ABSTRACT FROM AUTHOR]

The wear behavior of an as-received Mg-Zn-Y-Zr alloy before and after a facile heat treatment was investigated under sliding in air and 0.5 wt.% NaCl solution. Results revealed that the wear resistance of the alloy was remarkably enhanced after the heat treatment, irrespective of testing condition. The wear mechanism was predominantly abrasive wear accompanied by oxidation under the dry sliding condition, while corrosive wear was dominant under sliding in the NaCl solution. The superior corrosive wear resistance was attributed to the homogenous distribution of fine I-phase precipitates in the alloy by the heat treatment, leading to a reduction in wear, corrosion as well as wear-corrosion synergy. The wear-accelerated corrosion rate was remarkably alleviated after the heat treatment. [ABSTRACT FROM AUTHOR]

Tribocorrosion is a severe problem in dental implants, artificial joints, and other implants, and it will affect the long-term safety of the implants. To improve the deficiencies of titanium alloys, we combined physical vapor deposition technology and anodic oxidation to prepare TiN to embed TiO 2 nanotube composite coatings (NTNTs-TiN). Results show that the hardness of the NTNTs-TiN composite coatings reaches 33.2 ± 0.6 GPa, and the grains of the composite coatings were further refined. The NTNTs-TiN coating has the smallest average coefficient of friction (0.22) during tribocorrosion. The tribocorrosion resistance of NTNTs-TiN coating in SBF is increased by ∼44 and ∼2 times compared with Ti6Al4V alloy and TiN coating, respectively. The capillarity effect of the lower contact angle of NTNTs-TiN can form a continuous water-lubrication film at the interface between the counter-ball and coating and produce a lubrication film composed of Ca, Mg, and P, which reduces the coefficient of friction significantly. The NTNTs/TiN composite coating exhibits the best synergistic effect of wear and corrosion. In addition, the NTNTs-TiN coating also exhibits excellent antimicrobial and corrosion properties, which provides a new solution for the long-term safe use of implants in the human body. [ABSTRACT FROM AUTHOR]

Conventional processes are performed to improve the low hardness and low wear resistance properties of 316L steel, but these processes generally decrease the corrosion resistance. Electroless nickel alloy coatings provide a hard, wear‐resistant, and corrosion‐resistant surface. Thus, the present study aims to investigate the wear, corrosion, and tribocorrosion behaviors of monolayer and duplex coatings with nickel–boron (Ni–B) and nickel–phospore (Ni–P) on 316L steel in comparison with 316L steel in dry sliding and 0.9 wt% NaCl solution environments. It is determined that the coatings have a mixture of crystal and amorphous structures, the interfaces on the 316L are uniform, and the compatibility between the layers is good. The Ni–B, Ni–P/Ni–B, and Ni–B/Ni–P coatings are 2.3, 2.06, and 1.6 times as hard as the 316L, respectively. The wear rates of Ni–B, Ni–P/Ni–B, and Ni–B/Ni–P coatings show decrease by 99.3%, 92.5%, and 99.1% in the dry‐sliding condition and by 98.5%, 30.1%, and 19.1% in the tribocorrosion condition compared with that of 316L, respectively. It is observed that the monolayer Ni–B coating exhibits superior hardness, a higher contact angle, low electrical conductivity, and better tribological performance in both dry sliding and tribocorrosion conditions compared to the 316L and duplex coatings. [ABSTRACT FROM AUTHOR]

The aim of this in-vitro study was to evaluate the influence of Ag + -ion-coated conditions on the corrosion, tribocorrosion and antibacterial properties of Ti15Mo alloy. The mean wear volume losses of all test specimens after tribocorrosion test procedures were determined using a noncontact 3D profilometer. The specimens' hardness, roughness values and microstructures were measured using the microhardness tester, surface profilometer, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The mean wear volume loss of 30-min Ag + -ion-coated Ti15Mo alloy was lower than the other specimens. In this study, correlations between the hardness, surface roughness and wear volume loss were found to be significant. The PVD coating process enhanced the antibacterial activity of Ti15Mo alloy owing mainly to the formation of silver film on the substrates. [ABSTRACT FROM AUTHOR]

Water-based lubrication faces the common challenge of component lifetime extension which is impaired by tribocorrosion due to material surface depassivation. However, such mechanisms in a pH-neutral and low-halide electrolyte require additional understanding. A ball-on-flat configuration study of hard-phase materials in a low amplitude–high frequency sliding contact against martensitic chromium steel with contact pressures around 200 MPa is presented. Under lubrication by purified water, tungsten carbide-based metal matrix composite (MMC) with NiCr binder and silicon nitride-based ceramic (SiAlON) against DIN/EN 1.4108 steel yielded coefficients of friction above unity. Wear scar enlargement led to fretting-like conditions with adhesion becoming the fundamental wear mechanism. A tribocorrosion-induced depletion of tungsten carbide and nickel was determined for MMC. SiAlON materials suffered extreme wear under the formation of abrasive SiO2, while heat-treated DIN/EN 1.4125 steel showed lower friction and wear, but also showed signs of hydrogen embrittlement. Results from accompanying single-material corrosion experiments could not satisfactorily explain the phenomena. Including galvanic interaction and the influence of contact geometry, a new tribocorrosion model for fretting conditions is proposed. It describes an expanding anodic belt located at the inner-most crevice position of an otherwise cathodically polarized material. Low conductivity of the electrolyte is seen as a key player in this process, while the galvanic situation between two materials in contact was shown to invert when water was substituted by a wet organic phase. [ABSTRACT FROM AUTHOR]

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There is an increasing concern over simultaneous wear and corrosion (tribocorrosion) issues that cause the material failure of stainless steel in marine environments. The main objective of this study is to understand the effect of tribocorrosion conditions on pitting susceptibility and synergistic material loss for AISI 304 stainless steel. For this purpose, tribocorrosion tests were conducted in a natural seawater-filled corrosion cell integrated with a tribometer. An alumina ball of 6 mm radius slid against AISI 304 stainless steel plates under 5 N and 7.5 N loads in natural seawater. The cyclic polarization scans were carried out under corrosion and tribocorrosion conditions in the natural seawater by applying different loads. Also, tribocorrosion tests were conducted under anodic (0.3 V), cathodic (−0.5 V) and Open Circuit Potential (OCP) to determine the effect of electrochemical potential on pitting susceptibility and material loss rate. The study revealed that electrochemical potential significantly affects pitting corrosion and material loss, and the material losses increased significantly from the cathodic potential to the anodic potential. Furthermore, the material loss of AISI 304 alloy during tribocorrosion in natural seawater due to corrosion was significantly lower than wear. The wear-corrosion synergism played an essential role in total material loss, confirming that wear and corrosion affect accelerated material loss positively. The material loss of AISI 304 is mainly due to pure mechanical wear and corrosion-induced wear. [ABSTRACT FROM AUTHOR]

In this study, the influence of the high-pressure torsion (HPT) processing parameters and solution treatment (ST) on the corrosion and tribocorrosion behavior of CoCrMo (CCM) alloys was investigated for possible usage in biomedical applications. The corrosion behavior of the CCM alloys was investigated by using potentiodynamic scanning (PDS) and electrochemical impedance spectroscopy (EIS) tests. Tribocorrosion tests were carried out in a reciprocating ball-on-plate tribometer at 1 Hz, 1 N load, and 3 mm stroke length for 2 h. All electrochemical measurements were performed using a potentiostat in standard phosphate-buffered saline (PBS) solution at body temperature (37 ± 2 °C). The samples were characterized by using a scanning electron microscope (SEM), transmission electron microscope (TEM), optical microscope (OM), and X-ray diffraction (XRD). The deepness and width of wear tracks were examined by using a profilometer. The results showed that HPT and ST processes did not affect significantly the corrosion resistance of samples. However, the ST-treated samples had a higher material loss during sliding in standard phosphate-buffered saline (PBS) at body temperature as compared to HPT-treated samples. [ABSTRACT FROM AUTHOR]

NiTi-based alloys subjected to aggressive tribocorrosion working conditions can deteriorate by the combined action of mechanical and chemical wear. The synergistic interaction under sliding contact and corrosive environment formed the basis of the current study. This study employed a linear reciprocating tribometer coupled with an electrochemical cell of a three-electrode configuration to investigate the behaviour of NiTiNOL60 alloy sliding against an alumina ball (Al2O3) in a NaOH environment. The resulting wear track surfaces were examined using a scanning electron microscope, optical microscope, energy dispersive spectroscopy (EDS), and stylus profilometry. While the synergistic interactions reveal that abrasive and oxidative wear mechanisms exist concurrently, an increase in applied load reduces the corrosion potential, thereby leading to a higher wear volume and increased corrosion rate. The experimental results showed that a higher corrosion rate and wear volume occurred at a higher load. The wear track analysis illuminated the various wear mechanisms at play, including abrasion, debris adhesion, pitting, delamination, ploughing, and cracking. These mechanisms were influenced by both mechanical and chemical wear, the latter notably due to corrosive attacks. EDS elemental analysis showed an increase in oxygen content at higher loads, which suggests increased corrosion due to the delamination of the oxide layer during the reciprocating sliding.

In this work, tribocorrosion performance of the High Power Impulse Magnetron Sputtering (HIPIMS) nitrided (F75) CoCrMo alloys was examined with the help of sliding wear corrosion experiments carried out in Hank's solution. Results indicate that under Open Circuit Potentials (OCP), both nitrided and the untreated specimens exhibited near similar Sliding-Wear-Corrosion coefficient (KSWC) values (6.52 × 10−15 and 3.95 × 10−15 m3N−1m−1 respectively). However, the benefits of HIPIMS nitriding were evident under accelerated corrosion (anodic potentials) and passivating conditions. KSWC values of the nitrided specimens were an order of magnitude lower (6.41× 10−15 m3N−1m−1) than the untreated specimens (3.4 × 10−14 m3N−1m−1), indicating that nitrided surfaces had higher resistance against tribocorrosive mechanisms. This superior performance was attributed to the formation of a nitrided microstructure consisting mainly of expanded austenite (ƔN) without the formation of the detrimental CrN phase, which resulted in high hardness and sustained resistance to corrosion. A rationale for lower synergy between wear and corrosion and its relation to the nitride microstructure has been presented.