Wear Damage Research Articles

Cavitation Resistance, Microstructure, and Surface Topography of Plasma Nitrided Nimonic 80 A Alloy.

Cavitation erosion of structural materials is a form of wear damage that affects the performance and life of components used in the aerospace, nuclear, and automotive industries, leading to an increase in the frequency of maintenance operations and redesign costs. The cavitation erosion behaviour of the nickel-based superalloy, Nimonic 80 A, was investigated using a piezoceramic crystal vibrator, according to the requirements of ASTM G32-2016. The results showed that plasma nitriding leads to a reduction in the mean erosion penetration depth by approximately ten times and of the erosion rate by the order of six times, compared to the solution heat-treated samples. Typical topographies of cavitation-eroded surfaces show a preferential degradation of the grain boundaries between the γ solid solution phases, of the twins’ boundary, and of the interface between the precipitated particles and the γ solid solution matrix. In the nitrided samples, the cracking initiation is determined by nitride particles, which are hard and brittle. Due to the high mechanical strength of the solid solution γ with the fcc crystal lattice, the appearance of the cavitation surface is uniform, and the fracture has a ductile character.

Probing the atomic-scale origins of anti-friction and wear-resisting in graphene-coated high-entropy alloys

Multilayer graphene (Gr) reinforced high-entropy alloys (HEAs) matrix composite shows promising prospects in anti-friction and wear-resisting. Nevertheless, a potential reinforcement mechanism at the atomic level urgently needs to be revealed. In the present work, through the molecular dynamics (MD) simulations, the friction and wear behavior of Gr coating reinforced HEA matrix composite on the basis of various normal loads and the number of Gr layers during scratching were analyzed. The coating effect of Gr was demonstrated to induce a substantial enhancement of anti-friction and wear resistance of HEAs matrix. Specifically, the narrowed distribution range of atomic forces combined with the counteraction between local pinning force and actuation force significantly weakened the friction. Meanwhile, the Gr coating-dependent inhibition of the pile-up effect was verified to substantially enhance the wear resistance. Especially, the increased Gr layers were validated to further reduce the friction and wear damage, attributing to the interlayer repulsion effect. Additionally, the experimentally detected reduction in scratch depth and inhibition of bulge behavior effectively supported our simulation findings. The analysis provides a theoretical insight to achieve superior surface performance and facilitates to prolong the service life of friction pairs.

A357 aluminium alloy produced by LPBF: Tribological behaviour in dry sliding conditions

Laser Powder Bed Fusion (LPBF) is increasingly used in packaging, automotive and aerospace sectors for manufacturing Al alloy components where fatigue and wear damage can readily occur. Therefore, this work aims to assess the tribological behaviour of A357 alloy (AlSi7Mg0.6) produced by LPBF as a function of both printing parameters and heat treatment conditions, applying a novel T6 based on rapid solution followed by artificial aging, which improves the strength-ductility balance. Dry sliding tests (block-on-ring) were performed using A357 samples as stationary blocks against rotating quenched and tempered AISI 52100 (100Cr6) steel. LPBF samples were compared with A357 obtained by sand casting, subjected to Hot Isostatic Pressing (HIP) and conventional T6 heat treatment. Microstructural refinement induced by LPBF carried out in optimised conditions, even without post-processing treatments, reduced the wear rate in comparison to conventional sand-cast, HIP-ed and T6 heat-treated A357, while maintaining comparable coefficient of friction. The rapid solution T6 did not worsen the tribological behaviour of as-built LPBF A357 components, even though it induced a slight hardness decrease.

Contact stress and sliding wear damage tolerance of hydroxyapatite and carbon nanotube reinforced polyethylene cup liner against zirconia femoral head

A finite element modeling (FEM) approach is carried out to estimate the contact stresses such as von-Mises and shear stress on the acetabular cup liner, made up of ultra-high molecular weight polyethylene (UHMWPE)-hydroxyapatite (HAp)-carbon nanotubes (CNT) based composites. The highlights of this work include the effects of liners' material (UHMWPE-HAp-CNT composites), radial clearance (0.05 to 1 mm), and liners' wall thickness (3 to 8 mm) on contact stresses. The thick liner (thickness: 8 mm) with conformal geometry (radial clearance 0.05 mm) produced the lowest contact stresses (von-Mises: 13.8–17.5 MPa and shear stress: 2.3–3.3 MPa). In contrast, the thin liner (thickness: 3 mm) with higher radial clearance (1 mm) showed the highest von-Mises stress (78.6–131.0 MPa) and shear stress (17.0–23.3 MPa). According to ISO 7206–1, nearly 6–7 times reduced contact stresses were observed because of the wider articulating contact area provided by thick cup liner and its conformity with respect to the femoral head. The UHMWPE-2 wt % CNT composite (UC) showed low von-Mises stress (16.1 MPa) and lowest shear stress (2.3 MPa); thus, it is the most damage tolerant material (wear rate: 2.6 × 10-7 mm3/Nm). The excellent mechanical properties such as hardness (165 MPa), elastic modulus (2.28 GPa), and tensile strength (36.7 MPa) are reasoned to elicit an increased sliding-wear resistance of UC. Thus, CNT-based UHMWPE composite can be the potential acetabular cup liner with a thickness of 8 mm and clearance of 0.05 mm without plastic deformation.

Semi-analytical methodology to predict fretting damage areas in angular contact ball bearing raceways under variable loading

Small reciprocal movements in bearings can cause wear damage at the contact between the rolling elements and the raceway due to fretting phenomena. This damage is also called false brinelling or fretting corrosion, attending to lubrication conditions and causes vibrations and noisy operation, finally resulting in the need for the replacement of the component. Previous works from the literature have focused on experimental analyses of the damage and methodologies to simulate the occurrence of this phenomenon. These previous methodologies are centred on the effects of isolated fretting modes, such as radial fretting, rotational fretting and tangential fretting. However, the effects of external loads in angular bearings lead to high complex scenarios in which multiple fretting modes act simultaneously. In response to this demand, a novel methodology has been developed to analyse fretting damage as a consequence of the variable load and rolling motion. In addition, an analysis of the effects of each fretting mode is accomplished to determine the need to simulate both. The validation of the method is accomplished in two stages. First, a numerical validation through the finite element method (FEM) shows good agreement in the calculation of the contact reaction, the contact angle and tangential stresses, with relative differences under 5% and a considerable time reduction. Second, an experimental validation, which show a 16.1% mean relative difference between the damage areas and a 76% mean overlap of the damage areas.

Research on infrared nondestructive detection of small wind turbine blades

To obtain the optimal light conditions for field infrared nondestructive detection of wind turbine blades, this paper used a 2kw small wind turbine blade with different damage types and degrees of damage as the research object. Using the passive infrared thermal imaging detection method, the damage of the wind turbine blade was naturally stimulated under outdoor conditions with enough light in summer to collect infrared thermal images, and the numerical simulation of the damage was performed. The experimental and simulation results show that light intensity has a large influence on damage detection, and the three typical damage of the best detection conditions are obtained. Among them, the light intensity of a foreign body attached reaches 950 W/m2 or higher for the best detection effect, while facial wear and crack damage were best detected at a light intensity of around 1000 W/m2 in the sunny noon. The simulation results agree well with the experimental results when using COMSOL multiple physical field coupling software for wear and crack damage scene reconstruction of finite element simulation, proving that the use of solar radiation as a source of passive infrared thermal imaging detection technology to detect wind turbine blade damage within a certain range of light intensity is feasible. Meanwhile, the numerical model was used to thermodynamically couple the wear-damaged blade, yielding a positive linear relationship between light intensity and the blade's highest temperature, stress, and strain. Furthermore, the degree of wear damage and the stress-strain corresponding to the highest temperature of the blade are both positively linear.

Experimental and computational investigation of fretting fatigue characterized by nominal contact pressure in dovetail structures

AbstractThe present work is aimed at establishing an engineering design method for fretting fatigue based on experimental and computational investigation of dovetail structures made of nickel‐based superalloy. Severe stress gradients and surface wear damage make fretting fatigue difficult to be assessed based on conventional fatigue life models. With the help of detailed experimental investigations and finite element computations, a fretting fatigue life model based on the nominal pressure on the dovetail contact surfaces was related to the nonlocal multiaxial fatigue analysis. The derived fretting design method based on the nominal pressure shows a life prediction distribution within the double‐scatter band and agrees with experiments fairly well. The present model provides an efficient and easy‐to‐use design method for engineering applications.

Influence of the relative humidity and H2S - SO2 polluted air on the fretting wear behavior of silver-plated electrical contacts

The use of connectors in electrical devices for automotive industry has significantly increased during the last decades. These connectors need to keep low and stable electrical contact resistance (ECR) otherwise disconnects may occur inducing critical failures. Close to the engine, these connectors are subjected to vibrations inducing fretting wear damage. The aim of this study is to investigate the influence of relative humidity and the presence of pollutant sulfurous gases (H2S, SO2) on the silver-plated electrical contact resistance (ECR) behavior. The ECR fretting endurance Nc (i.e. when ΔR> ΔRth = 4 mΩ) displays a fast increase above RHth(Air)=50%. The debris layer becomes more conductive so a larger wear volume is required to reach the ECR failure. At the same time, the debris layer becomes more cohesive and the wear rate decreases. Alternatively, synergic interaction between H2S, SO2 gases and relative humidity above RHth(Air&S) = 60% leads to the formation of lubricating Ag2S sulphide and Ag2SO4 sulphate tribofilm which, by decreasing the friction coefficient and the silver layer wear rate, sharply increases the ECR endurance. Finally, using simple explicit formulations, both ECR endurances under polluted and non-polluted air are formalized.

Atomistic understanding toward the improved scratching properties of GaAs coated with monolayer graphene

Molecular dynamics simulation was performed to study the surface nanotribological behavior and subsurface damage of gallium arsenide (GaAs) substrate coated with monolayer graphene when subjected to the scratching action of diamond abrasive. Simulation result shows that the coefficient of friction and wear volume of GaAs/graphene surface are evidently lower than those of the bare GaAs surface for various scratching depths. The material removal of the graphene-coated GaAs workpiece is primarily attributed to compression- and shear-induced plastic deformation of GaAs, whereas abrasive wear is the dominant material-removal mechanism for bare GaAs workpiece. On the contrary, the GaAs workpiece coated with graphene exhibits severe subsurface damage due to the higher stress and that graphene can suppress the stress released within the GaAs workpiece during scratching; hence, the stress has to spread deeply. The scratching-induced slight deformation of graphene occurs when the scratching depth is higher than 15 Å. The deformed graphene induced by scratching is still capable of protecting GaAs substrate to some extent, but its C-C bond is vulnerable to be ruptured at the end of the scratching path due to a scratching-induced bulge structure. Increasing temperature can promote the scratching-induced surface wear and subsurface damage of GaAs workpiece. Monolayer graphene can improve the surface tribological properties of GaAs at each temperature. This work can provide atomic insights into the antifriction and antiwear design for GaAs when graphene is used as a coating.

Study on strip WEA wear damage and fatigue spalling of U71MnG rail material by laser quenching treatment

The wear damage and fatigue spalling behaviors of the martensite strip white etched area (WEA) prepared by subjecting the U71MnG steel to laser quenching were studied. The results showed that the wear mechanism of the strip WEA surface changed from a combination of oxidation wear and adhesive wear to oxidation wear with increasing number of cycles. The uncoordinated deformation of the substrate and strip WEA initiated the formation of cracks at their interface. Moreover, the low thickness of WEA at the initial position and plastic deformation of the substrate in front and below accelerated the WEA spalling. At the middle position, the increase in the WEA bulge made it bear a larger load, leading to a more significant rheological displacement of the strip WEA than that of the substrate. The cracks were preferentially initiated at the interface and then propagated to the surface and depth of WEA to form branch cracks. The main crack propagated through WEA to the underlying substrate, causing severe spalling. At the end position, the plastic flow of the substrate formed the sheet metal on the strip WEA surface.

Use of synchrotron X-rays for direct observation of wear damage in optically-opaque contacts by means of CT imaging and X-ray diffraction

In a simulated in-situ experiment annular contacts of 6082-T6 aluminium alloy were first exposed to various degrees of fretting wear, before synchrotron X-ray CT and diffraction were applied to examine the extent and development of wear damage. The wear volumes measured and development of the wear rate were consistent with the mathematical wear model of Fillot, Iordanoff & Berthier. Thickness and porosity of the worn zone were measured and the contact area between wearing elements estimated. Developments of residual strain and tribologically transformed structure were investigated through X-ray diffraction. This study demonstrates, for the first time, the value and viability of observing and quantifying wear through combination of X-ray CT and diffraction opening a path towards in-situ observations of wear.

Einfluss von Eiskollisionslasten am Propeller auf die Kontaktzustände in den Antriebsstranggleitlagern von Schiffen

Journal bearings in drive trains of ships in Arctic and Antarctic operations show wear and fatigue damage resulting from collision between the propeller and drift ice. The damage requires costly drivetrain maintenance in dry dock, which can be reduced by loadappropriate design and predictive maintenance measures However, this requires a reliable life time calculation of marine drive train bearings subjected to stochastic ice loads. In the following investigations, the influence of different load characteristics of a propeller-ice collision on the contact states in the drive train bearings of ships is investigated in order to be able to estimate the influence of different load characteristics in terms of the development of future life time models. For the investigations, a MBD and EHD model of the drive train of the research vessel SA Agulhas II was built. The results show that the load characteristics “load duration”, “load height” and “load orientation” and the operating parameter “oil temperature” have a high influence on the contact states in the drive train bearings and must be taken into account for future life time calculations.

Contact Characteristics at Interface in Three-Body Contact Conditions with Rough Surfaces and Foreign Particles

Nanoparticles as lubricant additives under a certain average diameter and concentration may reduce wear, friction and scuffing damage. However, atmospheric dust particles affect not only human health but also the efficiency of components, and even cause component failures. Therefore, the contact characteristics at interfaces with foreign particles require careful investigation. In this work, a 3-body microcontact mechanics concept is used to analyze the effects of wear debris and foreign particles on real contact area, contact mode, asperity deformation type and separation at interface. The results show that the relationship profile between dimensionless real contact area (At*) and dimensionless normal contact load (Ft*) is wedge-shaped in a 3-body contact interface. Using surface-to-surface 2-body contact area as upper bound and surface-to-particle 3-body contact as lower bound, the 3-body hybrid contact situation is in between upper and lower bounds. As the dimensionless normal contact load increases, At* increases gradually as well. The order of contact mode is p-s contact, hybrid contact and then s-s contact. If the 3-body contact interface is in hybrid contact mode, the decrease in the hardness and average third body diameter will cause the At* to increase significantly at the same Ft*. Conversely, the separation and real contact area ratio of plastic deformation decrease gradually. The turning point of contact area (TPCA) occurs when the contact mode is within hybrid contact mode and the ratio of average third body diameter to the composite equivalent surface RMS roughness is about 50–70% for foreign particles and wear debris. When the Ft* is slightly larger than Ftpca*, the third body and surface share the total interface load approximately equally which will help reduce the real contact pressure and plastic contact area to improve surface performance.

Corrosion resistance improvement of the Ti6Al4V/UHMWPE systems by the assembly of ODPA molecules by dip coating technique

Living with degenerative diseases, such as arthritis and osteoporosis, is challenging if orthopedic devices manifest adverse effects caused by corrosion processes. Ti6Al4V alloy is used to manufacture orthopedic implants due to its excellent mechanical and osseointegration properties. Nonetheless, it has poor resistance to wear and corrosion by biological fluids and mechanical activity. This degradation process generates the need to improve the corrosion resistance of metallic biomaterials used as biomedical implants. Dip-coating technique is a wet coating method used to lessen wear damage on the metal surface and can produce coatings using a wide variety of molecules at a low cost. In this work, Ti6Al4V alloys were coated with ultra-high molecular weight polyethylene (UHMWPE) and Octadecylphosphonic Acid (ODPA) films forming a UHMWPE/ODPA bilayer coating by dip-coating method to improve protection efficiency against corrosion in phosphate-buffered isotonic saline solutions and proposed it as alternative coatings to delay the failure of medical implants. The optimization of individual coated systems were obtained with an immersion time of 40 s (Ti6Al4V/UHMWPE) and 30 h (Ti6Al4V/ODPA) with corrosion current densities of 1.51 × 10−9 A cm−2 and 6.8 × 10−8 A cm−2, respectively. The formation of bilayer coatings reduces the average roughness from 19.34 nm (Ti6Al4V/UHMWPE) to 12.67 nm (Ti6Al4V/UHMWPE/ODPA). ODPA deposition on UHMWPE films changes the corrosion rate by interfering with the anodic and cathodic reactions, reducing the corrosion rate to 7.46 × 10−4 μm y−1 and an estimated corrosion protection efficiency of about 99.99 %. The results show a superior performance as a protective barrier over the individual films (1.19 μm y−1 with 97.2 %, and 0.026 μm y−1 with 99.9 %, ODPA, and UHMWPE, respectively), improving the corrosion resistance of the Ti6Al4V alloys.

Improved bioceramic coatings reinforced by nanostructured talc

Nano-talc was successfully incorporated in the hydroxyapatite matrix via pulsed electrodeposition after being obtained using an eco-friendly liquid-phase exfoliation process. Scanning electron microscopy, atomic force microscopy, X-ray spectroscopy, Raman spectroscopy, corrosion and wear resistance, and cytocompatibility tests were used to characterize the biocomposite ceramics. Talc significantly improves the nanomechanical and wear properties of bioceramics (i.e., higher stiffness, reduced friction coefficient, and lower wear damage) as well as corrosion resistance. Talc does not induce cytotoxic activity in in vitro cells and may induce bone maturation as per biocompatibility tests.

Tribological Characteristics of Nano-Lubricated High-Speed Rolling Bearings Considering Interaction between Nanoparticles and Rough Surface

The embedding situation between various nanoparticles and rough surfaces affects the lubrication characteristics of rolling bearings. If not properly handled, this can easily lead to wear damage of rolling bearings. Therefore, the friction and wear mechanism of nano-lubricated high-speed rolling bearings under various nanoparticle embedded states is studied in this manuscript. Mixed oils containing different sized SiO2 nanoparticles and dispersants are prepared, and then the tribology test of nano-lubricated high-speed rolling bearings considering the interaction between various nanoparticles and the rough surfaces is conducted. The friction and wear properties such as coefficient of friction, wear volume and real-time temperature rise of high-speed rolling bearings under different embedding conditions are revealed, and the anti-wear mechanism of the nano-lubricated high-speed rolling bearings is obtained. The results show that compared to the complete non-embedded state, the complete embedded state of different nanoparticles effectively improves the anti-wear effect of the bearing. When the nanoparticle mixed oil is added, the bearing still has good anti-wear performance under the conditions of high speed and lack of oil. As for the light loaded rolling bearing adopted with nano-mixed oil, the coefficient of friction is appropriately increased, as well as the skid reduced, while the wear of the rolling bearing is effectively reduced. This research will provide theoretical basis and important reference for nano-lubrication and its application in aviation rolling bearings.

Prediction of Wear Failure in Journalpin Bearings

Wear damage is a common failure in engine bearing shells. Wear failure induces changes in the bearing geometry and affects the oil film pressure and the durability of bearing shells. In this paper, wear failure in journalpin (main) bearings of a reciprocating engine is studied. Using a dynamic model, forces and torques in the journalpin bearings have been calculated and used in the analysis. To calculate the lubricating characteristics of the bearing, such as minimum oil film thickness and maximum oil film pressure, the Elasto-HydroDynamic (EHD) model that incorporate mass conservation algorithms is utilized. Wear failure in journalpin bearings of a reciprocating engine is assessed and the results are presented. Archard’s model is used as a wear model of journalpin-bearing material. The asperity interaction of two rough surfaces is considered by the boundary lubrication model. The results show that the wear rate at the initial stage of engine running is high. The results indicate that the main reason for wear in the journalpin bearings is the applied torque on the bearing, leading to edge wear. In a V-12 or 6Inline engine, journalpin bearing number 4 has the highest amount of torque applied and therefore has the highest amount of wear.

Fretting fatigue behaviours of SiC reinforced aluminium alloy matrix composite and its monolithic alloy

This study presents the experimental and FEA (finite element analysis) investigations on the fretting fatigue behaviours of the metal matrix composite, 2124 Al–Cu–Mg alloy reinforced with 17 vol% of 3 μm SiC particles by a powder metallurgical route and its equivalent monolithic alloy, 2024. The predicted stress concentration and orientation from the nonlinear FEA stress analyses are aligned with the experimental observation including fretting wear damage and crack initiation and propagation. Compared with its equivalent monolithic alloy, the composite in the naturally aged condition (T4) demonstrates similar subsurface degradation but the crack propagation life is much shorter. In general, the composite has shown superior fretting fatigue performance in the low cycle regime (104 to 4x105 cycles) but not in the high cycle regime (4x105 to 107 cycles). Its fretting fatigue behaviour is interpreted in terms of higher wear resistance, delayed crack initiation, superior tensile strength in the low cycle regime. The reported fretting fatigue performance of the composite suggest the different material behaviours in low and high cycle regimes should be considered when developing a fretting fatigue damage model and assessing an engineering design.

Interfacial wear damage of CFRP/Ti-alloy single-lap bolted joint after long-term seawater aging

Interfacial wear damage is one of the primary causes of joint failure, especially in the marine environment since material aging greatly aggravates the wear damage between the contact interfaces of joint. In this paper, interfacial wear damage mechanism of CFRP/Ti-alloy single-lap bolted joint after long-term seawater aging was researched through the wear experiments and material microstructure analysis. The results show that CFRP demonstrates strong tribological anisotropy where 0° wear shows more serious wear damage than 90° wear. The wear damage of contact interface can be inhibited by surface treatment of Ti-alloy through reducing the hard contact. Long-term seawater aging has significant impact on the wear damage evolution of CFRP. The aging time and temperature exaggerate the hygrothermal effect, weakening fiber-matrix interface and intensifying the wear damage. The influence of salt concentration depends more on the presence of salt ions rather than their concentration.

Facile fabrication of PEI/BN/PDA hierarchical structure for boosting tribological performances of carbon fiber/resin composites matched with copper dual disk

Copper dual disks applied in the braking and transmission of vehicles and aircraft, were susceptible to the damage of shear force and friction heat, seriously affecting friction stability and service life. In this study, enhanced building blocks including polyethyleneimine (PEI), boron nitride (BN) and polydopamine (PDA) were employed to construct a hierarchical interfacial structure for boosting tribological performances of carbon fiber/resin composites paired with copper dual disk. Furthermore, this flexible/rigid/flexible reinforcement contributed to the formation of friction films and high-efficiency thermal conduction network, significantly reducing wear damage to dual disks. The drop in the wear rate of PEI/BN/PDA-modified composite reached 85.07%. Moreover, the wear rate of copper dual disk decreased from 1.63 × 10−8 cm3J−1 to 0.80 × 10−8 cm3J−1, showing a 50.92% decline.