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The purpose of this study was to investigate the tribological properties of NiTi shape-memory alloy that was borided and coated with Al2O3 using the electrophoretic deposition (EPD) method. For the study, the sample surface was borided for 1 and 4 h at 800°C with the method of pack boriding, and the surface of the sample that was borided was coated with Al2O3 using the EPD method. The tribocorrosion properties of the untreated samples, borided samples, and borided and (duplex) Al2O3-coated samples were investigated and characterized using XRD and SEM devices. Accordingly, following the boriding treatment on the NiTi material, Al2O3 coating was successfully carried out with the EPD method. In comparison to the untreated samples, the tribocorrosion resistance of the surface-treated samples under a load of 3 N in a 3.5% NaCl solution increased. Additionally, among all samples, those that were subjected to the duplex surface treatment had the best tribocorrosion properties.

The use of metallic biomaterials in the medical implant devices has become increasingly prevalent over the past few decades. Patients find themselves being exposed to metals in a variety of ways, ranging from external exposure to instruments such as medical devices to internal exposureviasurgical devices being implanted in their bodies. Potential health risks are associated with metallic wear debris in the form of nanoparticlesin situgeneration and the release ofin vitrometal ions into human biological specimen's circulation. In combination with mechanically accelerated electrochemical processes, this can lead to the release of toxic metal ions, nanoparticles or micro scaled debris in the surrounding tissues and body fluids bring about relevant health issues and contribute to implant loss of failure. Metal ions release from metallic materials; stainless steel, cobalt-chromium alloys, titanium and its alloys, and nickel-titanium alloys implanted into the human body in orthopedic surgery is becoming a major cause of concern. The degradation mechanisms of the metallic implants lead to implants failure and tissue inflammation. However, the levels of metallic ions in those fluids can vary depending on the involved degradation mechanism of the implant. After briefly recalling the clinical context, this article analyses thein vitrostudies on metals and metallic alloys corrosion, tribocorrosion and electrochemical corrosion under simulated inflammation conditions. Specifically, the present review reported the results ofin vitroexperimental investigations on the release of metal ions from metallic orthopedic implant materials, subjected to different electrochemical corrosion and tribocorrosion conditions, into simulated human body fluids.

open access article To improve the tribocorrosion performance of 316L stainless steel (SS), multi-layer (1, 2 and 3 layers) Fe-based alloy coatings were manufactured by laser cladding Fe-based amorphous powder on 316L SS, and the corrosive wear behavior was investigated against Alumina ball in Ringer's solution. With the increase of cladding layer number, the content of bodycentered cubic (BCC) phase increases, and the hardness also improved. The volume loss rate of SS at 5 N load decreased over 3 times by the 2-layer coating. Under 10 or 20 N loads, the 2-layer coating still presents the best tribocorrosion performance with the lowest values of friction coefficient and volume loss rate. The multi-layer cladding caused surface chemical composition change leading to the decrease of Cr accompanied with the increase of Mo and Y, which is responsible for the increase of BCC content and hardness as well as the formation of lubricant FeeCr hydroxide film. The friction induced lubricating film may facilitate to design new metallic coatings for the low carbon steels applied in corrosive environment.

In this study, the effect of the addition of vanadium (V) on the densification, microstructure, and wear behavior of borosintered powder metallurgy steels was investigated. Ball-milled powders containing 0, 1, 5 and 10 wt.% V were cold-compacted under 200 MPa pressure and then subjected to borosintering at 1100°C for 2 h in ambient air. The characterization of the boride layers formed after borosintering was conducted by scanning electron microscopy, X-ray diffraction, microhardness tests, nanoindentation, surface roughness measurements, and ball-on-disk-type wear tests. Wear testing was carried out under 10 N load for a total sliding distance of 250 m in ambient air and in a 3.5% sodium chloride (NaCl) solution. While the thickness of the boride layer decreased with increasing V content, its hardness and modulus of elasticity also increased, owing to the formation of additional vanadium boride (VB) and vanadium carbide (V2C) phases. Wear resistance increased with increasing V content, and the samples tested in 3.5% NaCl displayed lower coefficients of friction and higher wear resistance compared to the samples tested in ambient air. Reduced wear in 3.5% NaCl was attributed to the cooling and lubricant effects provided by the 3.5% NaCl solution.

The consequence of coupling wear (erosion/abrasion) and corrosion is not just simply the sum of wear in the absence of corrosive medium and corrosion in absence of wear. The so-called synergistic effect implies that corrosion is accelerated due to the removal of the passivating layer because of wear. On the other hand, corrosion can accelerate abrasion when the electrochemical dissolution yields a brittle surface layer which can be subsequently removed by abrasion. The synergism between wear and corrosion is complex and the interaction between mechanical and chemical factors governing tribocorrosion is not yet fully understood. This review aims at providing a general and thorough summary of the wear-corrosion interaction focused on stainless steels due to the technological relevance of these materials. It is taken into consideration the influence of the key parameters affecting wear-corrosion, such as the stainless steel type, slurry characteristics (temperature, pH, solid concentration), the erodent properties (particle size and shape), etc. The different models to describe wear-corrosion and the most used apparatus for tribocorrosion testing are also reviewed.

CrMoSiCN/Ag coatings were deposited on Ti6Al4V alloys at the trimethylsilane flow of 15 sccm using closed-field unbalanced magnetron sputtering, and their microstructures were observed and analyzed using SEM, XRD, XPS and TEM, respectively. The coatings’ mechanical properties were measured using nano-indenter. The tribocorrosion characteristics of Ti6Al4V and CrMoSiCN/Ag coatings were investigated in seawater using tribocorrosion tester. The results revealed that the nanocomposite coatings consisted of (Cr, Mo)N solid solution, Ag nanocrystal and amorphous SiCNx matrix. As the Ag target current increased to 1.0 A, a large amount of Ag nanoparticles were observed on the coating surface. The coating hardness initially increased to 21.0 ± 0.7 GPa at the Ag target current of 0.4 A and then declined. After the Ag element was added into coatings, their tribocorrosion characteristics were improved. The tribocorrosion characteristics of coatings were much better than those of Ti6Al4V. The tribocorrosion characteristics of CrMoSiCN/Ag coating at the Ag target current of 1.0 A were the best in seawater.

Titanium particles as a product of degradation have been detected in periimplant oral tissues and it has been assumed that implants were the source of these particles. Periimplantitis sites had higher concentrations of particles in comparison to healthy implant sites. Several factors have been identified in the degradation of dental implant surface, such as mechanical wear, contact with chemical agents, and the effects of biofilm adhesion. Titanium particles silently prompt the immune-system activation and generate a pro-inflammatory response in macrophages, T lymphocytes and monocytes. During the activation, inflammatory cytokines are released including, granulocyte–macrophage colony-stimulating factor (GM-CSF), prostaglandin, and TNF-α, IL-1β, IL-6. The nanoparticles depict unique features such as high level of biological reactivity and potentially harmful compared to microparticles since they have a relatively greater surface area to volume ratio. Allergic response to titanium as a cause of implant failure has not been well documented. Evidence demonstrating biological complication due to titanium particles release includes peri-implant tissue inflammation that lead terminally to implant loss. There is a biological probability for a relation between the presence of titanium particles and ions, biological complication, and corrosion, but there is no justifiable evidence for unidirectional series of causative actions.

The present work aims to study the corrosion and tribocorrosion behaviors of pure Al and Al-30 vol.% B4C fabricated by a combination of mechanical milling and hot-pressing processes. Structural analysis and phase composition of the pure Al and the Al-30 vol.% B4C composite were evaluated by field emission-scanning electron microscopy and x-ray diffractometry, respectively. The corrosion behavior was investigated using electrochemical impedance spectroscopy and potentiodynamic polarization in a 3.5 wt.% NaCl solution. Tribocorrosion tests were performed under an open-circuit potential in the same solution with a ball-on-flat configuration, and Al2O3 balls were used. Electrochemical studies revealed that the composite with 30 vol.% B4C presented lower resistance to corrosion as compared to the pure Al evidenced by a decrease on the corrosion potential, an increase on the corrosion current density and a smaller diameter of the semicircle presented in the Nyquist diagram. The results from the potentiodynamic polarization measurements showed that pure Al corroded at 58% slower rate when compared to the corrosion rate of Al-30 vol.% B4C composite. However, tribocorrosion tests showed that B4C particle addition to the Al matrix decreased the wear volume of the resulted composite from 1.48 to 0.03 mm3.

Purpose Ti6Al4V is a widely used metal for biomedical application due to its excellent corrosion resistance, biocompatibility and mechanical strength. However, a coupling reaction of friction and corrosion is the critical reason for the failure of implants during the long-term service in human body, shortening the life expectancy and clinical efficacy of prosthesis. Hence, this study aims to find a feasible approach to modify the service performances of Ti6Al4V. Design/methodology/approach Selective laser melting (SLM), as one of the emerging metal-based additive manufacturing (AM) technologies is capable for fabricating patient-specific personalized customization of artificial prosthesis joints, owing to its high adaptability for complex structures. This study is concerned with the tribocorrosion behavior of SLM fabricated Ti6Al4V substrate enhanced by laser rescanning and graphene oxide (GO) mixing. The tribocorrosion tests were performed on a ball-on-plate configuration under the medium of simulated body fluid (SBF). Moreover, the surface morphologies, microstructures, microhardness and contact angle tests were used to further reveal the in-situ strengthening mechanism of GO/Ti6Al4V nanocomposites. Findings The results suggest that the strengthening method of GO mixing and laser rescanning shows its capability to enhance the wear resistance of Ti6Al4V by improving surface morphologies and promoting the generation of hard phases. The wear volume of R-GO/Ti6Al4V is 5.1 × 10−2 mm3, which is 25.0% lower than that of pure SLM-produced Ti6Al4V. Moreover, a wear-accelerated corrosion of the Ti6Al4V occurs in SBF medium, leading to a drop in the open circuit potential (OCP), but R-GO/Ti6Al4V has the lowest tendency to corrosion. Compared to that of pure Ti6Al4V, the microhardness and contact angle of R-GO/Ti6Al4V were increased by 32.89% and 32.60%, respectively. Originality/value Previous investigations related to SLM of Ti6Al4V have focused on improving its density, friction and mechanical performances by process optimization or mixing reinforcement phase. The authors innovatively found that the combination of laser rescanning and GO mixing can synergistically enhance the tribocorrosion properties of titanium alloy, which is a feasible way to prolong the service lives of medical implants.

The YSZ coating was applied to 304 stainless steel substrate by atmospheric plasma spraying technology, and its electrochemical and tribological properties in 3.5 wt% NaCl solution were studied. In electrochemistry, under the action of cathode and anode potential, observe the changes of corrosion current density and EIS before and after wear. The results show that the YSZ coating has a very low corrosion current density during wear and corrosion compared to 304 stainless steel, and after the condition of the anode potential is applied, the effect of friction on the electrochemical impedance of the YSZ coating is very low, while the 304 stainless steel Impedance performance decreases; In terms of tribology, the friction coefficient of 304 stainless steel in 3.5 wt% NaCl solution is easily affected by potential, and the friction coefficient of YSZ coating relative to 304 stainless steel only changes under high potential. As the potential increases, the material volume loss of 304 stainless steel and YSZ coating increases linearly. From the data, the volume loss caused by the corrosion and wear of 304 stainless steel is much higher than that of YSZ coating.

Aims Dual mobility implants in total hip arthroplasty are designed to increase the functional head size, thus decreasing the potential for dislocation. Modular dual mobility (MDM) implants incorporate a metal liner (e.g. cobalt-chromium alloy) in a metal shell (e.g. titanium alloy), raising concern for mechanically assisted crevice corrosion at the modular liner-shell connection. We sought to examine fretting and corrosion on MDM liners, to analyze the corrosion products, and to examine histologically the periprosthetic tissues. Methods A total of 60 retrieved liners were subjectively scored for fretting and corrosion. The corrosion products from the three most severely corroded implants were removed from the implant surface, imaged using scanning electron microscopy, and analyzed using Fourier-transform infrared spectroscopy. Results Fretting was present on 88% (53/60) of the retrieved liners, and corrosion was present on 97% (58/60). Fretting was most often found on the lip of the taper at the transition between the lip and the dome regions. Macrophages and particles reflecting an innate inflammatory reaction to corrosion debris were noted in six of the 48 cases for which periprosthetic tissues were examined, and all were associated with retrieved components that had high corrosion scores. Conclusion Our results show that corrosion occurs at the interface between MDM liners and shells and that it can be associated with reactions in the local tissues, suggesting continued concern that this problem may become clinically important with longer-term use of these implants. Cite this article: Bone Joint J 2021;103-B(7):1238–1246.

Summary of the scientific communication presented in the 32nd Congress of the European Society for Biomaterials ESB2022, held during 4 - 8 September 2022 in Bordeaux, France, Upon implantation of any biomaterial, a biomaterial-based foreign response (B-FBR) is initiated. Immune cells are recruited to the implant site, being macrophages one of the key innate immune cell regulators of the biomaterial-based FBR. Implanted metallic materials may trigger cellular stress and they may induce adaptive responses in macrophages such as alteration of biological processes, depending on the cytotoxicity potential of the metallic compounds [1]. Moreover, upon implantation, metallic joint prostheses are subjected to degradation due to wear and corrosion, releasing metallic debris (metallic micro/nanoparticles and ions) which causes the risk of morbidity of biological and immunological responses. CoCr particles can cause local toxicity such as adverse local tissue reactions (ALTR, which includes aseptic lymphocyte-dominated vasculitis-associated lesion, necrosis, osteolysis and implant loosening, pseudo-tumors) and systemic toxicity (including cardiomyopathy, polycythemia, hypothyroidism, and neurological disorders) [2]. In this study, CoCr surfaces were subjected to wear-corrosion to generate metallic debris, and the worn surfaces impacted the macrophage response. Since an exhaustive characterization of macrophages in response to biomaterials is required, advances in new omics technologies, which allow massive expression analyses, may reveal new insights in the altered biological processes upon macrophage-biomaterial interactions [3]. Macrophage responses were characterized by a high-throughput proteomic approach. With this proteomic tool the biological responses of macrophages to worn CoCr surfaces were analyzed, elucidating the effect of wear-corrosion process on J774A.1 macrophages. The differential proteomics study allowed us to determine that: wear-corrosion process on CoCr surface impacted the macrophage response by inducing an increase in protein expression of Heme-oxygenase 1 (Hmox1) a well-known antioxidant protein involved in redox and metal ion homeostasis, which has been used as an indicator of cytotoxicity and oxidative stress induced by metallic biomaterials; J774A.1 macrophages were characterized by an antioxidant phenotype due to upregulation of REDOX mechanisms, which were activated probably to act as an adaptive response to counteract cellular oxidative stress and ROS associated to the wear-corrosion process applied on CoCr surface., This work was supported through RTI2018-101506-B-C31 and RTI2018-101506-BC33; and through PRE2019-090122, from Ministerio de Ciencia, Innovación y Universidades.

The nature of cathodic processes during the frictional interaction of aluminum alloy with ball corundum in the conditions of reciprocating motion has been studied. Under conditions of anodic polarization under conditions of friction, corrosion processes are activated and their speed during friction increases many times. The potential on the surface of the alloy under acid rain shifts sharply in the negative direction. Changes in the tribopotential and coefficient of friction are characterized by a gradual shift in values ​​at the initial stage of research. The oxide film is formed on the metal surface in neutral and acidic environments. The service life of the film is increased due to electrochemical protection during cathodic polarization at the electrode potential of pure alloy without oxide film. It is proved that polarization changes the life of the film in the initial stages and the loss of material and the coefficient of friction during the entire test period. It is established that the nature of surface fracture also changes as a result of application of the polarization potential during friction. The largest surface damage is observed during anodic polarization.

The high strength, elasticity, hardness and wear resistance of C17200 copper means it is widely used in motor brushes, bearing sleeves and contact parts. As the requirement for extended reliability and service life of industrial products increases, the demand for high-performance copper-beryllium (Cu-Be) will also increase. In this work, the wear mechanisms of C17200 alloy against GCr15 steel under dry conditions and in a 3.5% NaCl solution were investigated. X-ray diffractometry, scanning electron microscopy, energy-dispersive x-ray spectroscopy, a three-dimensional profilometer, and x-ray photoelectric spectroscopy were used to evaluate the wear damage and analyze the wear mechanisms involved. The results showed that the wear mechanisms of C17200 alloy under dry wear conditions were mainly adhesive wear, oxidation wear and delamination. During tribocorrosion, the effect of friction promoted the oxidation and corrosion of the specimen surface. The main wear mechanisms of tribocorrosion in a 3.5% NaCl solution were peeling and corrosion wear. In addition, the NaCl solution provided lubrication and could effectively reduce the wear of the materials. The results may guide improvement of the serviceability of Cu-Be materials in industrial environments.

In the present study, the influence of the electrochemical potential on the tribocorrosion behavior of X20Cr13 in 0.15 molar NaCl-solution was investigated with the aid of a universal-tribometer under potentiostatic control. The resulting material loss was determined through laser confocal microscopy, while the morphology of the wear tracks and the deformation of the material structure near the surface were observed using light and scanning electron microscopy. The results showed a clear dependence of the material loss and the wear mechanisms from the applied potential. Within the cathodic region, a small amount of the material degradation could be attributed to a strong adhesion and resulting strain hardening as a consequence of an electrochemical weakening and mechanical destruction of the passive layer. The maximum of wear during polarization at the free corrosion potential under friction was explained by galvanic coupling between the wear track and the passive surface near the stability threshold between Fe2+-Ion and Fe2O3development. Through increasing Polarization onto the free corrosion potential in the absence of friction and into the passive region, a decrease in material loss could be observed which is presumably attributed to the stable passive layer that inhibits electrochemical degradation and favors the formation of a grain refinement zone that slows down mechanical destruction.

To enhance the tribocorrosion properties of chemically bonded phosphate ceramic coating (CBPCC), GO-ZnO was prepared and added into CBPCC. And the tribocorrosion behaviour of CBPCC was investigated. Results show that, with the introduction of GO-ZnO, the open circuit potential of CBPCC shifts in a positive direction and corrosion current density decreases. In addition, the total material loss, the total mechanical wear loss and the total electrochemical corrosion loss of CBPCC all decrease with the increase of GO-ZnO. The wear track of CBPCC after tribocorrosion without GO-ZnO is rough and porous, while the wear track becomes smooth and dense with the incorporation of GO-ZnO. The material in wear track is anchored by GO-ZnO due to the strong bond between GO-ZnO and CBPCC, which decreases the wear loss. Because of the extra force from the tribocorrosion experiment, the material anchored by GO-ZnO forms to a dense structure which prevents electrolyte diffusion into CBPCC. Moreover, GO-ZnO can block the electrolyte diffusion pathway and make it more tortuous. The resistance to the electrolyte diffusion decreases the corrosion current density and the increased wear loss due to electrochemical corrosion.

Tribocorrosion behaviors of typical austenitic (ASTM 316), martensitic (ASTM S41500), and ferritic (ASTM S44660) stainless steels were investigated in a 3.5% NaCl solution under cathodic protection conditions, and variations in the microstructures and chemical compositions of worn surfaces were further analyzed. The results showed that the friction coefficient and wear rate of austenitic steels were lower than those of ferritic and martensitic steels in 3.5% NaCl solution with cathodic protection. Additionally, the tribocorrosion properties of ferritic steels were obviously unaffected by load. Wear mechanisms of the three typical stainless steels mainly included abrasive wear at lower loads and plastic deformation at a higher loads. Furthermore, in austenitic steels, variations in microstructure and chemical composition confirmed that a higher load was beneficial to the transformation of austenite to martensite; thus, the hardness and wear resistance were improved. Compared with austenitic steels, the phase compositions of martensitic and ferritic steel were more stable during sliding, and the surface hardness of martensitic steel increased due to the surface phase and microstructure transformations induced by sliding. In addition, the total damage to steel was mainly caused by mechanical wear and the interaction between corrosion and wear. Therefore, ASTM S44660 and 316 were suitable for high-load corrosion-wear environments and low-load corrosion-wear environments, respectively, providing guidance for material selection under practical conditions.

The present work is mainly focused on the macroscopic and microscopic examination of failed tungsten carbide (WC-Co) drill bits to find the root cause of the insert’s failure. Different failed WC-Co tool bits have been observed macroscopically and found that the inserts have failed due to shear-off, cracks, and gradual wear. The FE-SEM and AFM micrographs have been used to understand the different degradation and the tribocorrosion mechanisms of WC-Co inserts. Typical shape change mechanisms of individual WC grains have also been studied in detail with the help of FE-SEM micrographs, which have been influenced by the tribocorrosion in the presence of the mining environment. Ultrasonic cleaning method has been used to clean the inserts for the microscopic examinations. Various morphologies of fragmented WC grains have been examined to understand the shape change mechanisms of WC grains. The different electrode potential between the Co binder and the WC grains is the primary cause of the micro-galvanic form of corrosion. Hence, in the present study the wear and corrosion mechanisms of WC-Co insert along with the possible approaches to reduce the tribocorrosion have been discussed in detail. It was found that the proper understanding of tribocorrosion mechanisms is essential for the selection, development, and advancement of the suitable WC-Co tool materials.

The lubrication by ionic liquids (ILs) is a promising means for reducing wear and friction. Nowadays, phosphorus-, sulfur-, and halogen-free protolytic ionic liquids (PILs) are becoming increasingly popular. As compared to other ILs, they are cheaper and easier to produce. In this work, three protolytic ionic liquids composed of different amines and oleic acid have been studied. Phosphorus-containing ionic liquid, engine oil, and synthetic base oil have been used for comparison. The studies have been performed using a tribometer with a sliding reciprocating motion for a ball–plane friction pair. The friction pairs have been tested at a temperature of 30°C and under a load of 1 N for 30 min. In the study, three friction pairs based on different metals such as steel–steel, steel–stainless steel, and steel–aluminum have been used. The results show that ILs are efficient in reducing friction, but the lowest friction coefficient does not always coincide with the lowest wear level. A phosphorus-containing IL had the best lubricating properties in this study. The investigated PILs provide the most efficient lubrication in the case of a steel–steel friction pair. In this case they are much more efficient than motor oil. PILs form an adsorption layer that exhibits an extremely low friction coefficient on the surface of steel. However, owing to an intense tribocorrosion process, the PILs are not suitable for the lubrication of friction pairs containing stainless steel and aluminum.

Laser-based surface modification methods are employed to augment the surface properties of engineering components. In the presented work, pulsed laser remelting of Ti6Al4V surfaces using a long pulsed laser was used to generate ripple-like micro-features with different feature sizes. The resultant surfaces exhibited improved corrosion and tribocorrosion resistance. Anisotropic wetting characteristics of the laser remelted surfaces led to elongation of water droplets on the surfaces. The osteogenic potential of the surfaces as well as the orientations of human mesenchymal stem cells on the surfaces were dependent on the surface features. On surfaces having 20 μm ripples, differentiation of stem cells towards osteoblastic lineage was higher than that on acid etched surfaces, and the cells were prominently oriented across the ripples, parallel to the laser scanning track. On the other hand, surfaces having 100 μm ripples suppressed the cellular activities on them. While the resistance to corrosion and tribocorrosion of laser remelted surfaces can be attributed to the evolved microstructure and the formation of stable oxide layers, the physical characteristics like topography and wettability dictated cellular behavior on the surfaces. Taken together, the work demonstrates the use of pulsed laser remelting as a simple yet potentially effective route towards manufacturing Ti6Al4V orthopedic implants with improved biofunctionalities.

Wear and tribocorrosion of passive oxide film covered metals have been studied at the micro and macroscopic scales. Recent advances in nanotechnology have contributed to breakthroughs in understanding of fundamental friction and wear mechanisms of atomically thin 2D materials at the nanoscale. However, for metals and materials without ultra-flat surfaces, a gap in knowledge exists at or below a few nanometers, which is too small for continuum mechanics theories and experiments including conventional atomic force microscopy (AFM) methods, due to resolution limits arising from surface roughness. Here, we report the near-atomic-scale wear of titanium in air and physiological solution from a single atomic layer to beyond the full oxide thickness using an AFM-based tribology method. Sub-nano to nanometer wear of titanium was revealed with different stages of contact pressure dependent wear regions identified as wear depth increased, featured by a transition from atomic wear (below 2.4 GPa) to elasto-plastic driven wear (above 3.6 GPa) at its oxide thickness (3.8 nm) in air. Higher stress was required to generate a similar wear penetration process in PBS compared to air. Tribocorrosion at this scale was grain orientation and voltage-dependent. Our study opens up a new method to achieve reliable angstrom-level resolution wear quantification to advance the understanding of wear and tribocorrosion of metals at the nanoscale. Statement of significance Experimental tests of wear for metallic biomaterials at the nanoscale are difficult because engineered metal surfacesare never perfectly atomically flat, limiting the resolution of precise wear measurements to a few nanometers scale or more. To systematically address this problem, we have introduced the AFM ‘image-wear-image’ tribology method and obtained quantitative stress dependent measurement of the near-atomic-scale wear of titanium surfaces in air and tribocorrosion in physiological solution from a single atomic layer to beyond the full oxide film thickness. This allowedto measure sub-nano scale wear by partial removal of oxide. Nanoscale wear has been found to be grain orientation-dependent above the ‘atomic scale’ wear region. The nano-tribocorrosion of CP-Ti across scales and voltage effects on oxides in physiological solution was studied. Our study opens up a new method for future studies to advance the understanding of sub-nanoscale and nanoscale wear and tribocorrosion phenomenon as well as oxide growth mechanism of metallic biomaterials.

Sliding tribocorrosion behaviours of AISI 316 stainless steel were investigated against alumina ball in natural seawater environment (SWE) under 5 N loads. OCP (open circuit potential), potentiostatic (−1 V and 0.3 V) and potentiodynamic measurements were enforced to understand the influence of the sliding wear and electrochemical potential on tribocorrosion behaviours of AISI 316 stainless steel in SWE. Tribocorrosion experiments were conducted with a ball-on-disk type reciprocating tribometer integrated with the three-electrode potentiostat. The wear track surfaces were examined by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and optical profilometry. Mechanical effects reduced corrosion potential under both OCP and potentiodynamic scans in tribocorrosion conditions. Ploughing effects on the wear track were evident at the OCP and −1 V potential because of the predominance of mechanical effects. Pits were determined to develop due to the formation of the galvanic couple between worn and unworn surfaces after the tribocorrosion test, which was conducted under 0.3 V potential. The reduction of the contact area because of the pits and the lubricating effect of the oxides on the surface caused the lowest coefficient of friction (COF) in the wear zone at 0.3 V potential. Besides, COF obtained under −1 V cathodic protection potential (0.35) was less than in OCP condition (0.37) since it only occurred by the wear effects. The study also revealed that material loss from the wear track increased from cathodic potential towards anodic potential.

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.

Producción Científica, Medical implants manufactured using biomaterial Ti-6Al-4V exhibit some disadvantages. Its higher elastic modulus than that of natural bone can cause stress shielding problems. This can be avoided using Ti-6Al-4V with pores in the implant structure. However, poor corrosion and tribocorrosion behaviors are yielded because of the large area exposed to the medium. To mitigate both issues, coating technologies can be applied. The plasma electrolytic oxidation (PEO) process is a cost-effective process that has been used successfully in nonporous Ti alloys. In this study, two PEO coatings with different amounts of Ca/P are used. However, reports regarding their application in porous materials are scarce. The effects of PEO treatments on corrosion and tribocorrosion in Ti-6Al-4V powder metallurgy are analyzed herein. The porous materials provide an efficient surface for PEO coatings, as demonstrated via scanning electron microscopy (SEM) and atomic force microscopy (AFM), and the porosity of the substrates improved the adherence of the coatings. The corrosion resistance measured via electrochemical impedance spectroscopy confirmed the beneficial effect of the coatings, particularly for long exposure time. The lower roughness, small pore size, and more compact film observed in the PEO-Ca/P sample resulted in favorable tribological and corrosion properties., Ministerio de Educación y Ciencia (project RTI2018-097990-B-I00), Junta de Castilla y León (projects VA275P18 and VA044G19)

In this study, TiN, TiAlN monolayers, and TiAlN/TiN multilayer ceramic films on the surface of Ti45Nb substrates were formed via the cathodic arc physical vapour deposition process. The samples were characterized by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy, nano-indentation testing and surface tension testing. The corrosion performance of the samples was evaluated via potentiodynamic polarization and electrochemical impedance spectroscopy measurements and their tribocorrosion behaviour was evaluated by a ball on flat reciprocating tribotester in which the tribological contact was immersed in the electrolyte. The obtained structural and mechanical results indicated that multilayer films have finer grain sizes, and more stable and harder film structures compared with the monolayer coatings. Moreover, the surfaces of the samples exhibited different wetting characteristics. While uncoated and single layer (TiN, TiAlN) coatings showed hydrophilic behaviour, the multilayer coating exhibited hydrophobic behaviour. During the corrosion and tribocorrosion tests, all of the coatings showed a protective feature due to the ceramic structure of the coatings against corrosion and tribocorrosion. Among all of the ceramic coatings, the best results were obtained for the multilayer film.

The tribocorrosion behavior and degradation mechanism of 316L stainless steel, in four typically industrial corrosion media, under different potentials, were studied. The results indicated that they strongly depended on corrosion medium and electrode potential. When the potential increased from cathodic protection region to anodic region, corrosion was accelerated. It dramatically promoted mechanical wear which even dominated the total material loss. As a result, the total material loss increased sharply, though the material degradation directly caused by corrosion was slight. This phenomenon was more noticeable when the media were more aggressive. Especially in NaCl solution, the occurrence of pitting corrosion at anodic potential dramatically accelerated the degradation of the stainless steel. There was a special case in NaOH solution under cathodic protection potential. The corrosive reaction could still occur and couple with wear, which led to the abnormally great material loss compared with that in other corrosion media.

Corrosion and wear products of metallic implants can lead to severe adverse tissue reactions. However, there is an absence of effective means to reduce the tribocorrosion of metal. The main purpose of this study is to reveal a mechanism of engineering a barrier layer on metal surfaces via adding functional particles into the polymer counterpart. B4C and BN particles were compounded into a polyetheretherketone (PEEK) matrix and their tribological performance of PEEK-based composites sliding against stainless steel was compared in simulated body fluid. Results demonstrate that the addition of B4C reduces significantly friction and wear. In particular, the addition of only 1 vol% B4C reduces wear of PEEK by up to 94.8%, and tribocorrosion of steel is also obviously mitigated. It is discovered that hydrolysis of B4C particles triggered by friction and deposition of Ca2+ and phosphate ions dominate formation of the barrier layer at the friction interface. The barrier layer endows the PEEK–metal sliding pair simultaneously enhanced anti-wear and anti-corrosion performance.

The two-layer and multi-layer Cr/CrxN coatings were fabricated on 316 L stainless steel (316 L SS) substrates by the arc ion plating technique. The two-layer Cr/CrxN coating was a typical CrN coating with an adhesive Cr layer. And the multi-layer Cr/CrxN coating design was in two dimensions. In the first dimension, the multi-layer Cr/CrxN coating consisted of alternative Cr/CrN layers with the thickness ratio of 1:5; in the second dimension, the alternative Cr2N layers with the thickness of 10 nm were inserted in CrN layers. This design was expected to increase transverse interfaces in a smaller scale. The microstructures, mechanical, corrosion and tribocorrosion performances of both Cr/CrxN coatings were systematically investigated. The results showed that the special multi-layer design of Cr/CrxN coatings improved mechanical, anti-corrosion and anti-tribocorrosion performances. Compared with the two-layer Cr/CrxN coating, the reduced tribocorrosion damage of the muti-layer Cr/CrxN coating was closely related to the inhibited synergistic effect between electrochemical corrosion and mechanical wear. In conclusion, the multi-layer Cr/CrxN coating was more suitable to work as the surface protective coating than the two-layer Cr/CrxN coating in seawater.

This paper quantitatively determines the effects of the wear and corrosion phenomenon in dental implant materials when subjected to a simulated oral environment. A dental implant is a mechanical system that undergoes tribo-corrosion at the interface between the implant and abutment alloy where material degradation is commonly seen. The wear coefficient, wear volume loss, wear depth and rate of corrosion of the 3 materials under consideration: Grade 5 Titanium (Ti6Al4V), Yttria Stabilized Zirconia and Zirconia Toughened Alumina are determined. Comprehensive evaluation of such tribo-corrosive mechanical systems in simulated oral environments will provide a clear understanding of the material loss that occurs due to wear and corrosion interactions at the interface between the implant and abutment alloy for combinations of various implant-implant alloy materials. The materials under consideration were subjected to dry sliding wear in accordance with the ASTM G99 standard for 12,000 cycles. The wear volume loss and coefficient of friction were recorded simultaneously for the pin | disc combinations. To replicate realistic conditions, a small surface area of the materials was subsequently subjected to the potentiodynamic polarization corrosion technique in accordance with the ASTM F2129 standard to reveal the concurrent changes in corrosion kinetics in the presence of Artificial Saliva, that is being used in-vitro to facilitate electrochemical behavior of the materials at bodily pH levels. The results indicate that Zirconia Toughened Alumina is better suited to resist material loss due to both wear and corrosion in dental implants.

The cyclic loading, in the corrosive medium of the human body, results in tribocorrosion, at the interface of the head neck taper junction of hip implants. The resulting metal ions and wear debris can have adverse effects on the local tissues. The force applied by surgeons to assemble the head-neck junction is proven to play a major role in the mechanics of the taper junction which in turn can influence the tribocorrosion damage. Recently, finite element method has been used to predict the material loss at the head-neck interface. However, in most previous finite element studies, the contribution of electrochemical corrosion has been ignored. Therefore, a detailed study to investigate the influence of the assembly force on the tribocorrosive behaviour of the head-neck junction, taking into account both the mechanical and chemical material removal, is of paramount interest. In this study, a finite-element-based algorithm was used to investigate the effect of assembly force on the tribocorrosion damage at the junction interface over 4 million cycles of simulated level gait. The patterns of the material removal in the modelling results were compared with the damage patterns observed in a group of retrieved modular hip implants. The results of this study showed that chemical wear, after four million cycles, for different cases, was in the range of 25%-32% of the total material loss. A minimum assembly force (4 kN for the studied cases) is needed to maintain the interlock in the junction. Increasing the assembly force above this value does not further reduce the material loss. The computational model was able to predict the damage pattern at the retrieved head-neck interface.

Ti6Al4V alloy composite coatings in-situ reinforced with TiB-TiN were deposited on Ti substrate using plasma spraying. Influence of plasma power (50 and 60 kW) and deposition speed (40 and 50 mm/s) on coating microstructure and bio-tribocorrosion performance was analyzed. Process parameters found to have strong influence on the tribocorrosion behavior and the material loss/damage of these coatings was found to be significantly less than that of Ti substrate. However, corrosion played a dominant role in affecting the wear and overall damage of all materials. Present in-situ composite coatings reinforced TiB-TiN exhibited superior tribocorrosion resistance than Ti substrate as a result of their high hardness and non-passivating nature.

CrMoSiCN nanocomposite coatings with a low C content were prepared on Ti-6Al-4V using an unbalanced magnetron sputtering system, and their corresponding microstructures, mechanical properties, and tribocorrosion performance were evaluated in detail. The results revealed that the CrMoSiCN coating had a compact nanocomposite microstructure consisting of CrN and Mo2N nanocrystallites, (Cr, Mo)N solid solution, and Si-C-N amorphous phases. Moreover, the coating exhibited superior mechanical properties with a hardness of 28.6 GPa and an elastic modulus of 273 GPa, owing to the solid solution strengthening effect. The tribocorrosion test results showed that the dominant failure of the Ti-6Al-4V alloy was caused by the corrosion contribution to wear behaviors (synergistic effect). The CrMoSiCN nanocomposite coating could effectively alleviate the material loss caused by the synergistic effect of corrosion and wear behaviors, leading to pure wear behaviors during the entire tribocorrosion process. The corresponding tribocorrosion mechanisms under the open circuit potential and dynamic polarization conditions were discussed in terms of their tribocorrosion behaviors.

Nickel oxide nanoparticles with the size of 218, 73, and 50 nm were added to Ni-P electroless coating to create NiO@Ni-P nanoparticle reinforced composite coating on a brass substrate. The nanopart...

CoCrMo alloys are commonly used in artificial joints. However, tribocorrosion phenomena have led to the search for improvements to diminish wear debris and ion release. Engineering of surfaces is a...

Mechanically assisted crevice corrosion in modular total hip replacements may lead to an adverse local tissue reaction (ALTR) with a variety of sequelae. Although an ALTR is most commonly recognized with metal-on-metal modular hip constructs, tribocorrosion at the head-neck junction of metal-on-polyethylene (MoP) total hip arthroplasties may also lead to an ALTR. We present a case of a 79-year-old woman with a history of MoP total hip arthroplasty who presented with unilateral leg swelling, joint pain, and stiffness and subsequently underwent revision for an ALTR secondary to mechanically assisted crevice corrosion. This unique case of lower extremity vascular compromise resulting from an ALTR is important because clinicians should consider corrosion-related ALTRs when treating patients with an MoP hip prosthesis presenting with new-onset lower extremity swelling.

We study the corrosion and tribocorrosion behaviors of hard alloys of the VN20 + Cr3C2 and VN20 + VC systems in solutions based on 3% NaCl with different рН values. In alkali media, the corrosion currents and friction coefficients are lower than in acid media, which is explained by the inertness of nickel. The VN20 + 1 wt.% Cr3C2 alloy has the highest corrosion and tribocorrosion characteristics.

In this work, a systematic investigation was carried out to study the electrochemical and tribocorrosion behavior of LY12 aluminum alloy sliding against Al2O3 pin in artificial seawater, using a pi...

Synovial fluid is dynamic in vivo with biological components changing in ratio and size depending on the health of the joint space, making it difficult to model in vitro. Previous efforts to develop synthetic synovial fluid have typically focused on single organic-tribological interactions with implant surfaces, thus ignoring interplay between multiple solution components. Using a Taguchi orthogonal array, we were able to isolate the individual effects of five independent synovial fluid composition variables: ratios of (1) hyaluronic acid to phospholipids (HA:PL) and (2) albumin to globulin (A:G), and concentrations of (3) hydrogen peroxide (H2 O2 ), (4) cobalt (Co2+ ) and (5) chromium (Cr3+ ) ions on macrophage viability and reduced glutathione production, local solution pH and the comprehensive CoCrMo alloy electrochemical response. While no single synovial fluid variable significantly affected the collective response, HA:PL ratio resulted in the largest impact factor (Δ) on 12 of the 13 measured responses with significant effects (p < .05) on the average macrophage survival rate and electrochemical capacitive state of the CoCrMo surface. Cluster analysis separated significant responses from all trials into three groups, corresponding to healthy, mild, or severely inflamed fluids, respectively; with the healthy synovial fluid composition having mid-range HA:PL ratios with no Co2+ ions, and the severely inflamed fluids consisting of low and high HA:PL ratios with H2 O2 and Co2+ ions. By utilizing the Taguchi approach in combination with cluster analysis, we were able to advance our knowledge of complex multivariate synthetic synovial fluids influence on macrophage and electrochemical behavior at the cell-solution-metal interface.

Pure Al coating and Al2O3 particles reinforced Al composite coatings were prepared by arc-spraying. The feedstocks were pure Al wires and Al-based cored wires containing 10, 20, 30 vol.% Al2O3, respectively. The evolutions of microstructure, porosity and microhardness of the coatings with different Al2O3 contents were investigated. Microstructural analysis shows that the addition of Al2O3 particles improves density and decreases the porosity of the coating. The average hardness of the composite coatings varies from 39 to 416.5 HV0.1 as Al2O3 content increases from 0 to 30 vol.%. However, the microhardness of the Al matrix in the coatings increases first and then decreases as a function of Al2O3 contents. The tribocorrosion tests were performed under potentiodynamic polarization conditions in 3.5 wt.% NaCl solution. The cathodic shift of open circuit potential and the increase in current density are induced by sliding wear. Compared with pure Al coating, the Al2O3 particles reinforced composite coatings display a lower wear rate and coefficient of friction. The Al-20 vol.%Al2O3 composite coating shows superior resistance to tribocorrosion. The tribocorrosion mechanism of the composite coatings is delamination coupling of corrosion wear.

Mechanically assisted crevice corrosion may disrupt passive oxide films on medical alloys and lead to rapid repassivation reactions which generate corrosion currents and shifts in electrode potential due to the non-equilibrium nature of the reactions and the transient unbalancing of anodic and cathodic reactions. This study presents a theoretical approach to predict currents and voltages over time utilizing the concepts of heredity integrals, area-dependent surface impedance, contact mechanics and the high field physics of oxide repassivation. Two heredity integrals are presented relating, first, the sliding mechanics and oxide film repassivation physics to the current, and second, relating the electrode potential to the current using impedance concepts. Current-potential-time responses to controlled fretting conditions were measured across a fretting frequency from 0.2 to 10 Hz and compared to theoretical results. The coupled integrals were shown to predict the overall current-potential-time behavior for CoCrMo alloy surfaces under several controlled fretting corrosion conditions (loads, sliding speeds, etc.) with a high degree of similarity. These models can be adapted to numerical analyses of tribocorrosion to predict performance.

The release of debris and ions from metallic artificial joints during bio-tribocorrosion posed a severe threat to patient health. In this work, the lifecycle of a CoCrMo alloy was presented by investigating the subsurface microstructure transformation in-vitro. The results showed that the originally coarse grains changed to nano-grains (NGs) on the top region of the alloy, and nanoparticles (NPs) were torn off the surface, which were then blocked by the tribo-film. The agglomerated alloy NPs contained in the tribo-film transformed into debris after being removed from the alloy surface. The majority of the torn-off NPs were corroded and released ions into solution due to their high chemical activities.

Adverse local tissue reactions (ALTRs) were first associated with patients with failed metal-on-metal surface replacements and total hip arthroplasty (THA). However, an increasing number of cases of ALTR in metal-on-polyethylene (MOP) THA patients is being reported. Clinically, ALTR appears as benign, aseptic masses or bursae in the periprosthetic tissues. Histopathologically, ALTRs are distinguished by an intense lymphocyte infiltrate, destruction of the synovial surfaces, widespread necrosis, and fibrin exudate. Tribocorrosion of modular junctions appears to be the cause of ALTR in MOP patients. The various tribocorrosion damage modes occurring at modular junctions produce metal ions and a diversity of particulates in relation to size, chemical composition, and structure. The mechanisms by which these various products of tribocorrosion lead to ALTR are still a matter of considerable research. This review clarifies what constitutes ALTR, its relationship to implant factors, and highlights current methods for diagnosis and management of patients with ALTR in the setting of MOP THA.

Increasing cases of adverse local tissue reactions (ALTRs) associated with metal release have been observed in patients with metal-on-highly crosslinked polyethylene (MoP) hip implants, the most common design in total hip replacements. Studies have demonstrated the metal release from fretting corrosion at the head-neck junction, but rarely investigated tribocorrosion associated metal release at articulating surfaces in MoP hip implants. The objective of this study is to investigate both tribocorrosion at the articulating surfaces and fretting corrosion at the head-neck junction in CoCrMo femoral heads, as well as their association with metal species released in periprosthetic tissues and body fluids in MoP hip systems. Twenty-three patients with ALTRs associated with MoP implants were included. Systematic analyses were performed on the wear damage in articulation, corrosion at the head-neck junction and their correlation with degradation products observed in synovial fluid, periprosthetic tissues, and serum. Results showed that tribocorrosion at the articulating surfaces contributed to the elevated concentration of both Co and Cr ions in serum, while fretting corrosion at the head-neck junction mainly released Co ions to serum. Both tribocorrosion at the articulating surfaces and fretting corrosion at the head-neck junction released particles rich in chromium and phosphate, the dominant particles found in synovial fluids and tissues. This study provides strong evidence that tribocorrosion at the articulating surfaces in MoP hip implants could result in significant metal release. This information should be taken into account when studying the mechanisms of ALTRs and developing strategies of preventing metal release in total hip replacements.