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This study aims to achieve in situ-formed pure Ti and Ti6Al4V coatings on 316L stainless steel through hot pressing and examine their wear and corrosion properties thoroughly in two simulated body fluids: physiological serum (0.9% NaCl) and Hanks' solution. The sintering and diffusion bonding process was conducted at 1050 °C under a uniaxial pressure of 40 MPa for 30 min in a vacuum environment of 10−4 mbar. Following sintering, in situ-formed pure Ti and Ti6Al4V coatings, approximately 1000 µm thick, were produced on 316L substrates approximately 3000 µm in thickness. The mean hardness of 316L substrates, pure Ti, and Ti6Al4V coatings are around 165 HV, 170 HV, and 420 HV, respectively. The interface of the stainless steel substrate and the pure Ti and Ti6Al4V coatings exhibited no microstructural defects, while the interface exhibited significantly higher hardness values (ranging from 600 to 700 HV). The coatings improved corrosion resistance in both electrolytes compared to the 316L substrate. Wet wear tests revealed reduced friction coefficients in 0.9% NaCl relative to Hanks' solution, highlighting the chemical interactions between the material surface and the electrolyte type and the significance of tribocorrosion in biocoatings. [ABSTRACT FROM AUTHOR]

Chemical mechanical planarization (CMP) is a technique used to efficiently prepare defect-free, flat surfaces of stainless steel (SS) foils and sheets that are implemented in various modern devices. CMP uses (electro)chemical reactions to structurally weaken the surface layers of a workpiece for easy removal by low-pressure mechanical abrasion. Using a model CMP system of 316/316L stainless steel (SS) in an acidic (pH = 3.63) slurry with alumina abrasives, citrate buffer (CB), and H2O2, we examine the tribo-electrochemical mechanisms of SS CMP that dictate the designs of functionally efficient and cost-effective CMP slurries. The use of CB as a pH-controlled complexing agent prevents defect-causing dissolution of SS and eliminates the need for using separate (often toxic) corrosion inhibitors in the slurry. A material removal rate of 8.6 nm min−1 is obtained at a moderate down pressure of 0.014 MPa with a platen rotation speed of 95 RPM. Electrochemical techniques are strategically combined with mechanical abrasion of SS test samples to probe complex CMP mechanisms that are not readily accessible with electrochemical experiments alone. Corrosion-like reactions of salt-film formation at the SS surface act to enable the CMP process, where corrosion-induced wear plays a major role in material removal. [ABSTRACT FROM AUTHOR]

Most of the reported corrosive-wear or tribocorrosion tests have been carried out using an inert and insulating counter-body in the experimental set up, with the purpose of eliminating the direct contribution of the counter-body to the electrochemical response during sliding wear. Little work has been reported using the same material as the test specimen and as the counter-body. In this work, corrosive-wear experiments have been carried out on the same material contact, i.e., stainless steel on stainless steel (SS-SS), where a 316 SS specimen was sliding against a 316 SS slider in 0.5 M NaCl solution under controlled electrochemical conditions. For comparison purpose, similar experiments have also been conducted on the 316 SS-Al2O3 sliding pair. The tests were conducted under reciprocating sliding conditions at 1 Hz frequency, 4 N load and for a duration of 7200 s, incorporated with electrochemical control which included potentiodynamic polarization and potentiostatic polarization at constant negative and positive potentials with respect to the open circuit potential. The results show that the counter-body has a large effect on the corrosive-wear behaviour of the 316 SS specimen under all test conditions. As compared to the SS-Al2O3 sliding pair, the SS-SS pair experiences larger material removal from the specimen. Adhesive wear occurs in the SS-SS pair which leads to significantly roughened sliding surfaces and unstable frictional behavior and electrochemical response. Further analysis revealed that mechanical wear plays a more dominant role in material removal in the SS-SS pair than in the SS-Al2O3 pair, and it is the corrosion-accelerated wear that contributes to the significantly increased material removal in the SS-SS pair. [ABSTRACT FROM AUTHOR]

This study presents an investigation into the tribological, corrosion, and tribocorrosion properties of AISI 316Ti (austenitic) and AISI 430 (ferritic) stainless steels. The comparative analysis focuses on microstructural characterization, hardness, and a series of tribological, electrochemical, and tribocorrosion tests conducted in 0.9% NaCl using a specialized linear tribometer to reveal the quality of the studied materials in tribocorrosion applications. Friction tests were performed under both dry and corrosive conditions, while tribocorrosion tests were conducted under open circuit potential (OCP) conditions in 0.9% NaCl, with the electrode potential of the test specimen monitored during friction. To evaluate the electrochemical behavior of the materials, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were conducted using a 0.9% NaCl solution. The measured corrosion potential (Ecorr) suggests that AISI 430 is thermodynamically more stable than AISI 316Ti; however, AISI 316Ti demonstrated higher polarization resistance (RP) values compared to AISI 430. The findings indicate that material qualities significantly influence the coefficient of friction (CoF). Additionally, a notable antifriction effect of 0.9% NaCl was observed during tribological testing, resulting in a lower CoF compared to dry friction conditions. A cathodic shift in OCP during tribocorrosion testing was also observed in both materials, indicating an increase in corrosion vulnerability when the passive layer is degraded. [ABSTRACT FROM AUTHOR]

An atmospheric plasma spray deposition process was adopted for coating regular-shaped, Stellite 6 powder directly on a rolled 3mm size AISI 304 austenitic grade stainless steel substrate without any intermediate bond layers. Coating thickness as measured in a scanning electron microscope was obtained as 74 μm, 128 μm, and 215 μm. An experimental investigation of the functional behavior such as corrosion, microhardness, and erosion of the coated steel at different operating temperatures was undertaken to determine the suitability of its application in the industry. Erosion tests were conducted in an air jet tribo-tester utilizing alumina as an erodent with normal impingement angle at room temperature, 300∘C, and 600∘C. It was difficult to identify a single coating thickness that can be satisfactorily used for superior erosive wear properties with corrosion resistance. So modern management tools such as tri-vector and technology sieve analysis procedures as identification techniques were adopted for the selection of the best coating thickness by complying with the mechanical, erosion, and corrosion resistance properties. Steel coated with 128-μm coating thickness provides the best result for a combination of functional characteristics. [ABSTRACT FROM AUTHOR]

Surgical ASTM F139 stainless steel is used for temporary fixtures in the biomedical field. Tribocorrosion is a major concern in this application. The aim of the present work was to study the interplay between tribocorrosion behavior and the surface chemistry of the ASTM F139 stainless steel in phosphate-buffered saline solution (PBS). Sliding wear tests were conducted against alumina balls at different electrochemical potentials: open circuit potential (OCP), cathodic potential (−100 mV versus the OCP), and anodic potentials (+200 mVAg/AgCl and +700 mVAg/AgCl). The normal load was 20 N. The wear volume was estimated based on micrographs obtained from the wear tracks using confocal laser scanning microscopy. Moreover, the wear tracks were also examined by scanning electron microscopy (SEM). The surface chemistry of the ASTM F139 specimens was analyzed by X-ray photoelectron spectroscopy (XPS). The wear volume was dependent on the electrochemical potential, being maximized at +700 mVAg/AgCl. Delamination areas and grooves were observed in the wear tracks. Detailed assessment of the surface chemistry inside the wear tracks allowed identification of the main chemical species and their relative quantities, thus enabling correlation of the passive film composition with the observed tribocorrosion behavior. [ABSTRACT FROM AUTHOR]

The advancement of nanotechnology has had an impact on the use of heat exchangers. Nanocoolants, which offer higher thermal efficiency than traditional coolants, have paid significant attention. These innovative fluids, which contain nanomaterials, not only have better heat efficiency but also improve energy efficiency compared to regular coolants. However, the presence of solid nanoparticles in the coolant may cause corrosion and erosion of tubes, leading to massive degradation of those parts. To evaluate the effectiveness of nanocoolant particles, this research was conducted by studying the impact of using nanocoolant on erosion-corrosion occurring on metal surfaces. The study focused on the erosion-corrosion of stainless steel (AISI 316) in coolant solutions containing nanoparticles. The experiments utilized a rotating cylinder electrode (RCE) with rotational speeds ranging from 0 to 1800 rpm and a temperature range of 30°C-70°C. The corrosion rate was determined using the linear polarization resistance (LPR) method, while the erosion was measured by calculating the average surface roughness of the samples. The design of the experiment (DOE) was utilized to find the mathematical expressions of the effects of the nanocoolant on erosion and corrosion. The findings revealed that the corrosion rate and surface roughness of the samples increased with an increase in temperature and rotation speed. Furthermore, the erosion-corrosion effects of the nanocoolant were less significant in stagnant conditions than in flow conditions, and significant differences were observed when compared with conventional coolant. Additionally, synergistic erosion and corrosion processes were detected at higher temperatures and higher rotation speeds for both types of coolants. [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]

The present study investigates the application of friction stir processing (FSP) on the degradation (wear, corrosion, and wear-corrosion synergism) response of cold spray additive manufactured (CSAM) 316L SS components. All tribological-based tests were conducted using a reciprocating ball-on-flat configuration in 3.5 wt% NaCl solution. Each degradation response was then correlated with the atomic, microstructural, and mechanical characteristics of the pre-and-post-FSP surfaces. In pure wear conditions, the austenitic phase transformation induced by FSP treatment decreased the frictional response and slightly increased the wear rate compared to the unprocessed CSAM substrate. In pure corrosion conditions, the densified surface enabled by FSP resulted in improved electrochemical resistance and a lessened corrosion rate. In wear-corrosion synergism conditions, the influence of FSP decreased the cumulative wear loss and wear-corrosion synergism of the CSAM substrate. It is believed that the combination of phase change, surface densification, and microstructural refinement induced by FSP are responsible for the improved wear-corrosion resistance. Based on these findings, it can be suggested that FSP is indeed a useful technique to improve the wear, corrosion, and wear-corrosion characteristics of CSAM 316L SS. [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]

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]

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]

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]

To extend the service life of the agitator blade, a series of [Cr–Fe4Co4Ni4]Cr2.6−xTixMo0.4 (x = 0, 0.3, 0.6, and 0.9) high‐entropy alloy (HEA) compositions based on the cluster‐plus‐glue‐atom model is designed, and HEA coatings are deposited on 904L stainless steel using the laser cladding technique. The phase structure, microhardness, wear resistance, corrosion resistance, and erosion properties of the HEA coatings are determined using X‐ray diffractometer, transmission electron microscope, a microhardness tester, a friction and wear tester, an electrochemical workstation, and an erosion testing machine, respectively. The coating's phase structure is made of FCC solid solution. The coatings' microhardness, wear, corrosion, and erosion resistance gradually improve by adding Ti. In particular, the microhardness of the [Cr–Fe4Co4Ni4]Cr1.7Ti0.9Mo0.4 coating reaches a peak value of 295.11 HV0.2, over 1.5 times that of the 904L stainless steel (190 HV0.2). Its specific wear rate (3.64 mm3 N−1 m−1) is lower than that of the substrate (8.53 mm3 N−1 m−1). The impedance of the [Cr–Fe4Co4Ni4]Cr1.7Ti0.9Mo0.4 coating is roughly 5.3 times of the 904L stainless steel. Simultaneously, the coating's cumulative volume loss rate of erosion–corrosion (0.054 mm3 h−1) is lower than that of the substrate (0.063 mm3 h−1). Consequently, the innovative HEA coating has an impressive overall performance. [ABSTRACT FROM AUTHOR]

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The seawater circulation pump is a significant piece of equipment in coastal nuclear power plants that is susceptible to erosion and corrosion in the seawater. In this work, CeO2-modified cobalt-based composite coatings were prepared on the surface of martensitic stainless steel by direct laser deposition. The effect of CeO2 on the phase composition, microstructure, microhardness, corrosion resistance, and erosion properties of the cobalt-based composite coatings was systematically investigated. While the addition of CeO2 did not affect the phase composition of the coatings that comprised γ-Co, γ-Ni, M7C3, and M23C6 (M = Cr, W, Fe) metallic carbides, the eutectic organization showed an obvious phenomenon of contiguous aggregation. Microscopic pores were found in the coatings with 2 wt.% CeO2, and the number of pores increased with the increase in CeO2 content. Despite the higher self-corrosion potential (−0.27668 V) of cobalt-based alloy coating compared to the substrate (−0.37019 V), indicating enhanced corrosion resistance, the difference in self-corrosion potential among coatings with varying CeO2 addition amounts is small (0.027 V), and the corrosion current densities are within one order of magnitude (10−8 A/cm2). These findings suggest that the addition of CeO2 has no significant impact on the coating's corrosion resistance. [ABSTRACT FROM AUTHOR]

Erosion-corrosion is a complex problem causing severe damage of austenitic stainless-steel equipment used in phosphoric acid production. Herein, time-resolved analyses of the acoustic emission (AE) signal together with the corrosion potential and weight loss were performed to online monitor and evaluate the dynamic degradation and depassivation of the 904L stainless steel under the effect of abrasive SiC particles. Important insights into the erosion-corrosion process are gained from the analysis of the AE waveform and its parameters. The characteristic root mean square (RMS) voltage and acoustic energy of AE signals revealed the self-healing difficulty of the passive film, of which the waveform of AE signals showed the appearance of imperfect continuous high intensity waveform, ranging from 0.1 to 0.4 mV. Evaluation of the average frequency spectrum showed that the amount of SiC particles alters the damage mechanism from AE events dominated by ploughing to AE events driven by micro-cutting. This suggests that the imperfect continuous waveform is possibly a precursor to the emergence of new acoustic sources (burst type): sudden jumps of chips from the cutting lips. This response resulted in a quasi-linearity in the mass loss of the alloy with the respective acoustic response at high particle loading (24 g L−1). The non-linear erosion-corrosion behavior suggests that the depassivation-repassivation events are dependent. These results render the combined AE and electrochemical analysis an effective sustainable approach for the online investigation of the synchronously changing erosion and corrosion rates. [Display omitted] • The dynamic evolution of stainless-steel degradation under erosion-corrosion conditions was unraveled. • Combined acoustic emission (AE) and corrosion potential measurements revealed the extension of surface depassivation and the difficulty of self-healing of the passive film. • At higher SiC loadings, the AE signals showed a high-intensity imperfect continuous waveform. • Analysis of the frequency spectrum and surface morphology demonstrated that the amount of SiC alters the surface damage mechanism. • Weight loss data and acoustic emissions signals are nicely correlated during erosion-corrosion. [ABSTRACT FROM AUTHOR]

Stainless steel pumps in food industries are prone to seizure during sanitation operations. To understand the tribocorrosion phenomena induced during the cleaning routine, tribological and tribocorrosion tests were carried out using three inexpensive, eco-friendly domestic cleaning solutions: 8 % acetic acid, and 5 % sodium hydrogen carbonate. Some tests were conducted in demineralized water, which served as a reference medium. High friction and wear were observed with AISI 316 L stainless steel in vinegar and water, consistent with current observations in food cleaning processes. However, in sodium hydrogen carbonate, an unprecedented tribological behavior was recorded under specific test conditions. Worn surface analysis results indicate that this phenomenon is associated with the formation of a passive film composed of chromium oxides/hydroxides and iron oxides/hydroxides, with the emergence of a nickel-rich sublayer. The electrical activity of the passive film demonstrated its insulating behavior. Due to the synergistic interactions between the mechanical wear of the passive film and chemical reactions of AISI 316L stainless steel in sodium hydrogen carbonate, significant improvement in the frictional properties of AISI 316L has been found, which can play an important role in increasing the mechanical life of equipment and energy efficiency. [ABSTRACT FROM AUTHOR]

The tribocorrosion behavior of the three representative dissolver materials, namely zirconium (Zr) alloy, 310 stainless steel (SS), and titanium (Ti) alloy in HNO 3 was systematically investigated by SEM, XPS, and Nanoindentation. The results revealed that Zr alloy possesses high corrosion resistance but a less favorable tribocorrosion resistance, whereas 310 SS presents a comparatively better tribocorrosion resistance but insufficient corrosion resistance. Moreover, both the coefficient of friction and wear loss of all three alloys were decreased at 0.8 V compared to −0.8 V, demonstrating an antagonistic effect of corrosion on wear, attributed to the lubrication and hardness enhancement of oxide layers. The present work offers a new perspective on the tribocorrosion behavior of continuous dissolvers used for reprocessing spent nuclear fuel. [Display omitted] • Tribocorrosion behavior of Zr alloy, 310 SS, and Ti alloy in HNO 3 was studied. • Zr alloy is high corrosion resistant but has insufficient tribocorrosion resistance. • 310 SS presents good tribocorrosion resistance but poor static corrosion resistance. • Antagonistic effect between corrosion and wear occurs on three alloys. • A tribocorrosion model of three dissolver materials in HNO 3 was proposed. [ABSTRACT FROM AUTHOR]

This work is devoted to studying tribotechnical characteristics of an experimental hard alloy, developed on the basis of the standard VK8 composition, during friction without lubricant against stainless steel 12H18N9T. The new composition is obtained by modifying the binder for tungsten carbide by partial replacement of cobalt with a (Fe+Cu) metal group. Comparative tribological tests of the experimental composition and VK8 were carried out according to the "pin on disk" friction scheme under a constant pressure and sliding speed at room temperature and with artificial heating of the tribocontact zone up to 300 °C. In the first case, the difference in the value of linear wear for both tribocontact alloys was minimal, while the experimental composition was characterized by the lowest friction coefficient. In the experiments with sample heating, the experimental alloy showed the least linear wear, while the friction coefficients for both cutting materials were statistically indistinguishable. The study of the friction surfaces also showed that the process of friction interaction between the experimental composition and stainless steel is characterized by a more intense (in comparison with VK8) adhesive transfer of the counterbody material to the indenter surface, as evidenced by numerous build-ups on hard-alloy samples and high values of the average roughness of friction tracks. [ABSTRACT FROM AUTHOR]

The simultaneous improvement of mechanical and corrosion resistance is of great significance for engineering applications. In this work, a novel lightweight amorphous structure AlTiVNb high-entropy alloy (HEA) film was fabricated by magnetron sputtering. The compression test of the AlTiVNb HEA film nanopillar exhibits a high compressive strength of up to 3.6 GPa and deformability approaching 58%. The high strength is affected by the disordered state, the nanostructure, and the lattice distortion effect, while the high ductility comes from the ductile shear band and the island structure. In addition, the AlTiVNb HEA film shows a current density of 4.90 × 10−8 A/cm2 and a potential of −0.234 V in the 3.5% NaCl solution, comparable to that of the 316L stainless steel. The chemical disorder state, cocktail effect, and homogeneous amorphous structure contribute to excellent corrosion resistance. This finding offers new insights into high-performance HEA films with robust mechanical and anticorrosion performances for microelectronic devices and mechanical metamaterials. [ABSTRACT FROM AUTHOR]

Al2O3, TiO2, and Al2O3-TiO2 coatings were deposited on AISI 304 stainless steel plates by the sol–gel dipping technique, and the effects of the coating composition on microstructure, wear, and corrosion characteristics were examined. Tribological features were determined by ball-on-disc sliding tests against an Al2O3 ball under a 10 N load, while corrosion properties were evaluated by potentiodynamic polarisation tests performed in 3.5% wt. NaCl solution. γ-Al2O3, α-Al2O3, and rutile phases were detected in the hybrid coatings. The highest coating thickness was obtained in single Al2O3 film and decreased with an increasing amount of TiO2 nanoparticles. The single Al2O3 layer had both the highest wear resistance and the lowest corrosion resistance. Although TiO2 addition caused an increase in the wear rate, it improved the corrosion resistance of the coating by filling the voids in the Al2O3 film. The Al2O3-TiO2 hybrid film with a relative ratio of 6:1 as a candidate for the wear- and corrosion-resistant coating decreased wear and corrosion losses of the 304 substrates by 83% and 97%, respectively. [ABSTRACT FROM AUTHOR]

To simultaneously protect the 304 stainless steel from corrosion and wear conditions, a FeCrMoCBSi coating with nearly full amorphous microstructure was deposited via activated combustion high-velocity air–fuel (AC-HVAF) technique. Initially, the porosity and microhardness of the coating were employed as two indicators to optimize the spray distance and powder feed rate. Then, the corrosion and reciprocating friction behavior of the best Fe-based amorphous (FA) coating and the bare 304 stainless steel were comparatively investigated. Experimental results show that the FA coating exhibited favorable corrosion resistance including high corrosion potential, low corrosion current density and additionally enhanced electrochemical impedance. Therefore, with FA coating deposited on the substrate, its surface was only subjected to slight etch pits instead of severe corrosion holes in a 3.5 wt.% NaCl solution. Besides, it is found that the sprayed FA coating could also effectively protect the substrate from severe abrasive wear and reduce its wear damage. The major wear mechanism was a combination of fatigue wear and adhesive wear derived from the micro-fracture and delamination at matrix and inter-splats. [ABSTRACT FROM AUTHOR]

Tribocorrosion is a recent paradigm of tribology defined as the combination of simultaneous mechanical and chemical wear of couplings. To date, this phenomenon is common in several engineering fields, such as the naval sector where marine equipment, offshore platforms and so on are clear examples. In this regard, the synergy between the mechanical and the chemical effects has a notable effect on the behavior of couplings in seawater environment. Nevertheless, the latter can act also as antagonistic factor. Hence, in this manuscript, an investigation was conducted on a tribosystem composed of an alumina sphere and a stainless-steel AISI 316 L flat, immersed in an artificial seawater solution of 3.8 % NaCl and a pH of 8.2. The analysis, carried out by a reciprocating tribometer equipped with a two/three-electrode potentiostat, was performed for different loads and frequency values, and their correlation with synergistic effects was investigated. The open-circuit potential, friction coefficient, tribocorrosive current and total wear were evaluated for different tribological conditions. It was found that the force and sliding velocity had a significant position in the synergistic response, passing from positive to negative mainly due to the protective action of oxide layer and lubrication behavior of corrosion products formed during the motion. Moreover, the current was modeled via two analytical laws discussed in literature, providing a good agreement with experimental data. Lastly, was provided the oxide thickness evolution formed on the samples surface and its relationship with total wear. • Tribocorrosion investigation of stainless steel 316 L for marine applications. • Analysis of the effect of tribological variables as frequency and normal load on tribocorrosive variables. • Discussion of the role acted by synergy (or antagonism). • Analytical modeling of the current in presence of sliding. • Oxide thickness evolution during the motion. [ABSTRACT FROM AUTHOR]

Plasma nitriding treatment of 17‐4 precipitation hardening stainless steels was carried out at 400 °C and 450 °C using a direct current unit. The nitriding layer thicknesses of the plasma nitrided at 400 °C and 450 °C were measured as 37.29 μm and 49.97 μm, respectively. The plasma nitrided sample at 400 °C presented dominant martensite and retained austenite phases; however, the height of main martensite diffraction peaks increased at 450 °C. The hardness results demonstrated that the samples at 400 °C and 450 °C were 2.9 and 3.1 times as hard as the untreated sample, respectively. The wear rate values of the sample at 450 °C showed a decrease by 19 % in the corrosive salt solution and 57 % in the dry‐sliding condition compared with that of untreated sample. The corrosion potential of the sample at 400 °C had more positive potential value and lower current density value than those of at 450 °C. The corrosion resistance of the sample at 400 °C improved due to the positive effect of the retained austenite phase. In this study, the wear was more dominant rather than corrosion, therefore plasma nitrided sample at 450 °C showed the best dry wear and tribocorrosion resistance. [ABSTRACT FROM AUTHOR]

The aim of this work is to obtain nanocomposite layers having a cobalt matrix with zirconium oxide nanoparticles (mean diameter 30 nm) through the electrodeposition process. The plating electrolyte suspension is prepared by adding ZrO2 nanoparticles in a sulfate-chloride cobalt electrolyte at a concentration of 0 and 10 g·L−1. The electrodeposition is performed at room temperature, using three current densities of 23, 48 and 72 mA·cm−2 and three deposition times of 30, 60 and 90 min. The influence of current density, time and nanoparticles concentrations on the characteristics of the obtained nanostructured layers are also discussed. ZrO2 ceramic nanoparticles as a dispersed phase in the cobalt deposition electrolyte modify the mechanism of its electro-crystallization, so they participate in this process by increasing the rate of cobalt deposition, confirmed by the thickness of the nanocomposite layers obtained. The paper presents some of the comparative results obtained regarding the thickness of the layers, the current efficiency and the inclusion of the nanoparticles into nanocomposite layers depending on the current density and time of the electrodeposition process. The analysis of Co/nano-ZrO2 nanocomposite layers with the help of optical light microscopy and electronic microscopy in cross-section highlights the good degree of adhesion of the layers to the metallic substrate made of 304L stainless steel. The results of the study show that as the current density and time increase, the thickness of the composite layers increases. The efficiency of the process is improved compared to the electrodeposition of pure cobalt layers. The degree of inclusion of ZrO2 nanoparticles increases with time and decreases with increasing of imposed current density on the electrodeposition process. The distribution of the dispersed phase in the cobalt metallic matrix is uniform. The layers obtained in this study can be applied in aircraft technology, in the automotive industry, as well as in biomedical applications in order to improve the properties and to increase the corrosion or tribocorrosion resistance in a specific environment. [ABSTRACT FROM AUTHOR]

The consolidation of ceramic particles into the metallic matrix is promising to translate their exceptional properties from the micro-scale to the macro world. Herein, four different 15-5PH stainless steel (SS) matrix composites: 15-5PH/TiB2, 15-5PH/TiN, 15-5PH/TiC and 15-5PH/WC were fabricated by directed energy deposition (DED). The introduction of TiB2 particles substantially refines the martensite grain size, however, fails to achieve the performance improvement due to the elemental segregation of Cr and formation of considerable macro- and micro-cracks. The TiN composite realises a simultaneous enhancement of strength and ductility due to grain refinement, however, fails to enhance the corrosion resistance due to the Cr element segregation. The WC and TiC composites achieve the balance between the improved strength and ductility coupled with simultaneous enhancement of corrosion resistance. This work demonstrates the substantial potential in developing martensitic SS matrix composites with excellent strength-ductility synergy and corrosion resistance. [ABSTRACT FROM AUTHOR]

In this paper there are presented some results obtained by open circuit potential and electrochemical impedance spectroscopy measurements from studies performed on the behavior of tribocorrosion on metallic implant biomaterials as: 304L stainless steel, Co/nano-CeO2 nanocomposite layer and Ti6Al4V untreated and oxidized alloy to form a nanoporous TiO2 film. The open circuit potential technique used in measuring the tribocorrosion process provide information on the active or passive behavior of the investigated metallic biomaterial in the biological fluid, before, during friction and after stopping the friction. Thus it clearly show a better behavior of Co/nano-CeO2 nanocomposite coatings as compared with 304L stainless steel to tribocorrosion degradation in Hank solution; as well the better behavior of nanoporous TiO2 film formed annodically on Ti6Al4V alloy surface as compared with untreated alloy to tribocorrosion degradation in artificial saliva Fusayama Meyer. The slight decrease in polarization resistance value resulted from electrochemical impedance spectroscopy measured during friction in the case of the Co/nano-CeO2 nanocomposite layer (four times smaller), compared to 304L stainless steel, whose polarization resistance decreased more than 1000 times during friction shows the higher sensitivity of stainless steel to degradation by tribocorrosion. The same behavior is observed when comparing the polarization resistance of untreated titanium alloy recorded during friction that is about 200 hundred times smaller, while the specific polarization resistance of the oxidized alloy with the nanoporous film of titanium oxide, decreases very little during friction, highlighting the beneficial effect of modifying the titanium alloy by anodic oxidation to increase its resistance to the degradation process by tribocorrosion. [ABSTRACT FROM AUTHOR]

Tribocorrosion is a degradation phenomenon of material surfaces subjected to the combined action of mechanical loading and corrosion attack caused by the environment. Although corrosive chemical species such as materials like chloride atoms, chlorides, and perchlorates have been detected on the Martian surface, there is a lack of studies of its impact on materials for landed spacecraft and structures that will support surface operations on Mars. Here, we present a series of experiments on the stainless-steel material of the ExoMars 2020 Rosalind Franklin rover wheels. We show how tribocorrosion induced by brines accelerates wear on the materials of the wheels. Our results do not compromise the nominal ExoMars mission but have implications for future long-term surface operations in support of future human exploration or extended robotic missions on Mars. [ABSTRACT FROM AUTHOR]

Orthopaedic metallic implant design is expected to meet two critical challenges—biocompatibility and mechanical strength. According to a survey conducted in 2017, the global market of implants will grow by ~46% by 2025. Researchers have been trying to alleviate the problems of these implants, namely, biocompatibility, microbial invasion, bio-inertness, corrosion, and wear. Surface modification techniques that operate at low temperature and diffusion-based processes are preferred to circumvent the problems. These methods include thermochemical (carburizing, nitriding, etc.), electrochemical processes (electrochemical deposition, chrome plating, etc.), and ion implantation. This review presents the significance of these methods while meeting various challenges, such as wear, biocompatibility, and corrosion. The implants reviewed are stainless steel, Co-Cr alloys, titanium alloys, and magnesium alloys. Finally, the friction-stir process, another low-temperature process, has been reviewed for Mg and its alloys. [ABSTRACT FROM AUTHOR]

In this study, chemically bonded phosphate ceramic coatings (CBPCCs) with different contents of aluminum phosphate (AP) are prepared on stainless steel (AISI 304L). Differential scanning calorimetry, X‐ray diffraction, contact angle test, and a tribocorrosion experiment are carried out to clarify the role of AP in the tribocorrosion performance of CBPCCs. The results show that, with the increase in the AP content, the enthalpy of curing increases because of the greater formation of the bonding phase AlPO4. Both in static corrosion and in tribocorrosion, the corrosion current density of CBPCCs achieves the lowest value when the weight ratio of AP to polytetrafluoroethylene is about 0.78. Additionally, the influence mechanism of AP on tribocorrosion is clarified. AlPO4 from the reaction between AP and Al2O3 has excellent mechanical properties and can enhance the wear resistance of CBPCCs by reducing the mechanical wear and the increased wear due to corrosion. The alumina particles wrapped by AlPO4 can form a dense and smooth surface and change the direction of electrolyte propagation, which leads to the increase in the tribocorrosion resistance of CBPCCs. [ABSTRACT FROM AUTHOR]

Tribocorrosion denotes an irreversible material degradation for several metallic components used in corrosive environments, and it arises from the interplay between chemical, mechanical, and electrochemical processes. In this study, some investigation has been performed to compare the tribocorrosion behavior of AISI 1045 steel and AISI 2205 duplex stainless steel sliding against an alumina pin in seawater. The lowering in the open circuit potential (OCP) of AISI 2205 during the tribocorrosion demonstrates that its protective passive film was damaged by wear and resulted in a wear-accelerated corrosion in the wear track. However, sliding was found to accelerate the corrosion of the unworn areas for AISI 1045, leading to an anodic shift of the OCP. Moreover, the total material loss increased with an increase in the applied potential for both materials. It was revealed that AISI 1045 was more sensitive to corrosion under sliding than AISI 2205. Therefore, pure corrosion loss and corrosion-induced wear constituted the primary reasons for the degradation of AISI 1045 at applied anodic potentials. [ABSTRACT FROM AUTHOR]

This work employed the "dissolution-diffusion-deposition" model to quantitatively describe the effect of N-Mo synergism on passivation process. The model was optimized by calibrating the ion concentration, calculating the equilibrium between H+ and OH−, as well as calculating the formation amount of passive film components. Through modelling studies, we visualized and quantified how N-Mo synergy promoted passivation process. Results demonstrate that N-Mo synergy enhanced corrosion resistance by suppressing acidification of solution, increasing Cr 2 O 3 content and improving cation-selectivity of passive film. The mutual promotion between hydrolysis of NH 3 and transpassive dissolution of Mo oxides played a critical role in improving corrosion resistance. [Display omitted] • The "dissolution-diffusion-deposition" model was optimized to improve reliability. • N-Mo synergy significantly enhanced the corrosion resistance of stainless steel. • Formation processes of passive film on stainless steels with different N and Mo contents were quantitatively studied. • Mutual promotion between NH 3 and MoO 4 2− played a critical role in strengthening passive film. [ABSTRACT FROM AUTHOR]

Cassava is the third most significant calorie source in the tropics. Its processing has changed from traditional methods to stainless steel processing machines. This study investigated the influence of cassava on metal release from two common stainless steels, ASTM 304 and 201, with and without friction, and on tribocorrosion (multi-analytically) of 304. Cassava was relatively corrosive and hindered repassivation of the surface oxide of stainless steel, but it also acted as a lubricant against mechanical friction. The combined action of friction and cassava caused a significant increase in iron, chromium, nickel, and manganese release from the stainless steels (30–35-fold increase compared to no friction, and 4–12-fold increase compared to water without cassava but with friction). [Display omitted] • Cassava, a widely used food sourced, is often processed in stainless steel grinders. • Cassava and friction-induced metal release from stainless steel studied. • Cassava increases metal release through chemical processes and hinders repassivation. • Cassava also lubricates the contact surfaces and decreases the extent of friction. • Significant release of stainless steel constituents into cassava food possible. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

To reduce the use of synthetic compounds as wear-corrosion inhibitors, and substitute them with new ecological compounds, we are interested in evaluating the effect of the essential oils against the tribocorrosion. The present paper describes the effect of adding Thymus zygis subsp. gracilis (TZ) essential oil (3 g·L−1) on AISI 304L tribocorrosion behavior in 0.5 M H2SO4. As a result, the addition of this essential oil decreases the tribocorrosion rate [E (%) = 84.38], the value of friction coefficient, and the energy dissipated during sliding wear, in comparison to those recorded for dry environment and 0.5 M H2SO4. In addition, the essential oil improves the surface morphology of metal as shown by the scanning electron microscopy and energy dispersive X-ray and the three-dimensional optical profiler analysis. In addition, the modeling approaches of experimental results, involving the density functional theory, the electrostatic potential, and the Monte Carlo methods, show that thymol (42.5% of TZ oil) is the best corrosion and tribocorrosion inhibitor that adhered to the stainless steel surface and offers a greater coverage area to block the metal wear-corrosion. According to the obtained results, the TZ essential oil can be used in the food industry to prevent the wear of materials. [ABSTRACT FROM AUTHOR]

To enhance the hardness and wear resistance of 304 stainless steel, Fe-based memory alloy/PZT piezoelectric ceramic (SMA/PZT) composite coatings with different PZT doping amounts (0.5–2 wt.%) were fabricated on 304 stainless steel by laser cladding. Coatings show good metallurgical bonding with the substrate. The microstructure, phase composition, microhardness, wear and corrosion resistance of the composite coating were investigated by scanning electron microscopy, X-ray diffractometer, microhardness tester, friction and wear tester and electrochemical workstation respectively. The results show that the microhardness, wear resistance and corrosion resistance of the composite coating are improved compared to the SMA coating. When the PZT doping amount is 1 wt.%, the SMA/PZT composite coating has the highest microhardness, and its wear and corrosion resistance are optimal compared to other coatings. It proved that 1 wt.% was optimal doping amount of PZT in the composite coating. [ABSTRACT FROM AUTHOR]

To investigate the effect of interaction between two single-Si3N4 particle-impingements on the repassivation of 304 stainless steel in a simulated groundwater, the corrosion current peaks of the samples during the impingement were recorded, and the micro-hardness of the substrate around the crater was tested. The results indicated that significant interactions between the two impingements were observed only when the value of distance-diameter ratio (L/d) was less than 1.5. With L/d being less than 1.5, the corrosion current peaks and mass losses due to the second impingements were higher than those of the first ones, and the re-passivation rates of samples during the second impingements were lower than those of the first impingements. Simultaneously, the microhardness of the substrate between the two craters was higher than that of the surface around one single crater with the same distance-diameter ratio. The mechanisms of how the L/d ratio influenced the interaction between the two impingements are also discussed. [ABSTRACT FROM AUTHOR]

Biomedical implants are immensely manoeuvered devices that fix various deformities and injuries on medical grounds. With an emergent exploration in this field by researchers, countless combinations of materials have been discovered that perks global mankind. The ultimate goal of this experimentation is to appraise the characteristics of wear and corrosion resistance of Ti–Co–Cr-coated 316L grade austenitic stainless steel (SS) in contrast with TiN-coated and uncoated 316L SS. A micro-abrasion test was conducted on every single sample at 3N, 5N and 7N loads and were characterized in accordance with weight loss, coefficient of friction, surface roughness, Scanning Electron Microscope (SEM) analysis, X-ray Diffraction pattern (XRD), Energy Dispersive X-Ray Analysis (EDAX), Fourier-transform infrared spectroscopy (FTIR) and corrosion resistance. The findings showed that Ti–Co–Cr-coated substrate at 3N load have good mechanical tolerance and offers admirable performance. The corrosion resistance of the specimens divulges the biocompatibility of Ti–Co–Cr as being more distinct because of the existence of titanium metal. [ABSTRACT FROM AUTHOR]

Super duplex stainless steels (SDSS) are used in offshore applications and oil/gas plants operating under severe service conditions due to their superior mechanical and electrochemical properties. Fracture toughness, wear and corrosion resistance of a material depends largely on its microstructure and can be improved by refining the latter. Friction stir processing (FSP) can be employed to refine the microstructure of the material, resulting in superior fracture toughness, wear, and corrosion resistance. In the present research, SAF 2507 SDSS was subjected to FSP with optimized processing parameters to study the influence of FSP on fracture toughness, wear, and corrosion resistance of the material. It was observed that FSP refined alloy grains by decreasing the grain size from an average of 160 µm in the base metal to 2-30 µm in the stir zone. Refinement of grains increased the hardness of the material, which enhanced its wear resistance by more than 15%. Wear track and debris analysis revealed the change in wear mechanism of the processed material. FSP also modified the surface composition of processed material, which served to improve its corrosion resistance by more than 80%. Morphology of the corroded surfaces of base and processed material showed that the processed material was more resistant to corrosive attacks than base material. FSP enhanced the grain boundaries in the processed region which improved the fracture toughness after exposure to accelerated corrosion by about 26%. Fractographic study revealed that processed material had brittle fracture behavior while base material had ductile fracture behavior. [ABSTRACT FROM AUTHOR]

Herein, bimodal‐reinforced AlCoCrFeNi complex concentrated alloy composite cladding on stainless steel 316L substrate using microwave hybrid processing is synthesized. Detailed microstructural analysis of the claddings shows the presence of cellular structure A2 (disordered BCC) with intermetallics (B2 (ordered BCC) and σ phases) at the intercellular regions. The presence of Cr23C6 is also observed for the reinforced claddings due to the dissociation of the SiC particles. The bimodal‐reinforced cladding shows the highest hardness (in excess of 800 HV) and fracture toughness (≈12 MPa√m), followed by micro‐ and nanocomposite claddings. Under slurry erosion condition, the bimodal composite cladding exhibits 10 times better erosion resistance than stainless steel 316L and nonreinforced cladding (1.5–2 times), respectively, at oblique angle followed by nano‐ and microreinforced unimodal counterparts. The outstanding performance of the bimodal composite cladding under both test conditions is related to higher hardness, fracture toughness, and resistance to plastic deformation. The detailed analysis of the eroded samples shows microcutting and ploughing as a dominant mechanism at an oblique angle while platelets, cracks, and microindents being the contributing factors for erosion at the normal impact angle. [ABSTRACT FROM AUTHOR]

In the present study, multilayered Cr–N/Cr–Al–N coatings were prepared by cathodic arc physical vapor deposition (PVD) with different numbers of layers and the same total thickness on AISI 630 steel in an attempt to improve the wear and erosion–corrosion resistance. Structural analysis of the coatings was performed by field scanning electron microscopy, X‐ray diffraction (XRD), and energy‐dispersive spectroscopy. Depth profiles and roughness parameters of worn surfaces were calculated after erosion and wear tests. XRD indicated that nitride compounds were formed in multilayer coatings by PVD. The Cr–N/Cr–Al–N coating exhibited superior corrosion resistance compared with AISI 630 substrate. The erosion–corrosion results revealed that the smoothest wear track with the minimum erosion rate and wear depth was obtained for five‐ and seven‐layered coatings. The failure mechanism of the bare substrate was influenced by plastic deformation via cutting and plowing, while the failure mechanism for coated samples was chipping and delamination. According to the wear results, the multilayer coatings showed a lower friction coefficient and better surface morphology that demonstrated their high ability for wear protection. [ABSTRACT FROM AUTHOR]

Ti/TiN multilayered physical vapor deposition (PVD) coatings were deposited on stainless-steel by cathodic arc deposition method. Bare sample of stainless steel 304 was compared with monolithic TiN coating and TiN coating having 2, 4, 6 and 8 Ti interlayers. The properties like corrosion and wear resistance were studied and analyzed comparatively. Potentiodynamic polarization curves showed that highest corrosion resistance was indicated by TiN coating with 8 Ti interlayers. Sample having 8 Ti interlayers have high corrosion potential (Ecorr) and low corrosion current density (Icorr) as compared to other samples. This may be attributed to the arrangement of interlayers that prevents the corrosive agents to penetrate surface. All multi-layered coatings show better results than the substrate material. Pin on disk wear test revealed that coating having monolithic TiN layer have the lowest coefficient of friction and consequently have less wear volume and wear rate as compared to other coatings with Ti interlayers. These results made the investigated coated stainless steel 304 valuable for wide range of industrial applications that required wear and corrosion resistance. [ABSTRACT FROM AUTHOR]

This work improves the tribological behavior via innovative surface designs for slipper pairs in seawater axial piston pumps. 316L stainless steel and carbon fiber/polyether ether ketone (CF/PEEK) were selected as friction pair matching materials due to their good corrosion resistance, self-lubrication, and wear resistance. One type of smooth surface and five different types of pit nonsmooth surfaces were created on CF/PEEK specimens. Rotational sliding tests were performed on a friction and wear tester at a load of 200 N at five different sliding speeds (0.79, 1.18, 1.57, 1.96, and 2.36 m/s) under seawater lubrication. The experimental results indicate that the friction process of the smooth surface friction pair is mainly based on abrasive wear and adhesive wear. The friction coefficient range is 0.05–0.08, the specimen contact temperature is 38–75 °C, and the wear rates of 316L and CF/PEEK are 2.3 × 10−5 to 1.2 × 10−4 mm3/(MPa·m) and 5.6 × 10−4 to 7.6 × 10−3 mm3/(MPa·m), respectively. Pits on the specimen surface produce a hydrodynamic effect and store wear debris. The friction process of the nonsmooth surface friction pair is mainly controlled by a ploughing mechanism with only a slight amount of adhesive wear. The friction coefficient range is decreased to 0.03–0.07, the specimen contact temperature is decreased to 28–54 °C, and the wear rates of 316L and CF/PEEK are decreased to 1.2 × 10−5 to 9.1 × 10−5 mm3/(MPa·m) and 2.6 × 10−3 to 7.1 × 10−3 mm3/(MPa·m), respectively. The geometrical arrangement of the elliptical and tri-prism pits increases the convergence gap range and produces a higher bearing capacity. As the sliding speed increases, the friction coefficient first decreases and subsequently slightly increases, the specimen contact temperature increases, and the wear rate decreases. [ABSTRACT FROM AUTHOR]

β-Nb 2 N, a transition metal nitride, has attracted significant interest due to its high hardness, high electrical conductivity, as well as its good corrosion and wear resistance. Herein, a simple novel method to prepare nanocrystalline β-Nb 2 N coating on 430 stainless steel substrate by disproportionation of Nb(IV) ions in molten salt is developed and presented. Through this method, a dense, crack-free, uniform, and well-adhered nanocrystalline β-Nb 2 N coating is obtained in NaCl–KCl–NaF–NbCl 5 –Nb melt at 850 °C for 5 h. Additionally, effects of temperature and duration on β-Nb 2 N coating formation are also investigated. Results indicate that higher temperature and longer duration are more favorable for β-Nb 2 N coating formation. Furthermore, the corrosion behavior of the coating was studied by potentiodynamic polarization in 3.5% NaCl solution. Result suggests that the β-Nb 2 N coating can significantly improve the pitting corrosion resistance of 430 FSS substrate. [ABSTRACT FROM AUTHOR]

Two different surface treatments are applied on 17-4PH stainless steel with laser techniques to improve mechanical properties and cavitation erosion–corrosion resistance. One involves laser precipitation hardening and the other implements laser cladding of Stellite 6 powder. The mechanical properties of the laser-treated surfaces are determined using nanoindentation test, and the cavitation erosion behavior of 17-4PH stainless steel with the laser-treated surface is investigated in 3.5 wt.% NaCl solution. The eroded surfaces are studied using SEM, and the depth data of the pits generated in the specimen surface are fitted into the extreme value analysis model to predict the maximum pit depth that may occur in the material surface with a given service life. Untreated 17-4PH stainless steel is also tested under the same conditions for comparison. It is shown that both surface treatments improve the mechanical and cavitation erosion–corrosion performance of 17-4PH stainless steel and laser cladding Stellite 6 treatment is even better. [ABSTRACT FROM AUTHOR]