Poor Wear Resistance Research Articles

Influence of Interlayers on Adhesion Strength of TiN Film on Mg Alloy

The wide application of Mg alloys has been restricted because of their poor corrosion and wear resistance. Titanium nitride ceramic films prepared via magnetron sputtering can improve the corrosion and wear resistance of Mg alloys. However, residual stress produced at the interface between the film and the Mg alloy substrate causes the TiN film to spall off and reduces its service life. One potential approach to mitigating residual stress involves enhancing the adhesive strength between the film and the substrate, thereby potentially extending the service life of the film. To increase the adhesion strength between the TiN film and the Mg alloy substrate, a Ti or Al interlayer was deposited on the Mg alloy by magnetron sputtering. Subsequently, the adhesion strengths of TiN/Ti and TiN/Al were determined under a single high shear force by scratch tests and were determined under multiple low shear forces by friction and wear tests. The results of scratch tests show that TiN with the Ti interlayer on the Mg alloy substrate has superior adhesion strength under a single high shear force. And the results of friction and wear tests show that both the TiN/Al and TiN/Ti films provided protection to the Mg alloy substrate against friction and wear, and TiN with the Ti interlayer on the Mg alloy substrate has superior adhesion strength under multiple low shear forces. This work can provide guidance for the selection of interlayers between Mg alloy substrates and hard ceramic films.

Effects of methane concentration on tribological properties of diamond films prepared on different ceramic substrates

ABSTARCT Diamond films were prepared on silicon nitride and zirconia ceramic substrates using hot filament chemical vapor deposition (HFCVD). The surface morphology, friction, and wear properties of the diamond films prepared with different methane concentrations (2%, 4%, and 6%) were compared using scanning electron microscopy, Raman spectroscopy, X-ray diffraction, and friction and wear testing machines. The results showed that, with an increase in the methane concentration, the diamond particles gradually changed from micro- to nanodiamonds, and the grain size first increased and then decreased. The diamond films on silicon nitride substrates were of excellent quality, with good wear resistance, strong adhesion, and wear rates of 2.857 × 10−8 mm−3•m−1•N−1, 5.151 × 10−8 mm−3•m−1•N−1, and 1.334 × 10−7 mm−3•m−1•N−1, respectively. The diamond films on zirconia substrates had more impurities on the surface, higher internal stress, poorer wear resistance, and weaker adhesion, with wear rates of 3.789 × 10−8 mm−3•m−1•N−1, 5.899 × 10−8 mm−3•m−1•N−1, and 2.074 × 10−7 mm−3•m−1•N−1, respectively. Hence, the deposition of diamond films on ceramic substrates significantly reduced the friction coefficient, and the performance of diamond films on silicon nitride substrates was excellent.

Improved dry sliding wear behavior of TA1titanium by low-temperature plasma nitriding by CCPN method

Cathodic cage plasma nitriding (CCPN) has been proven a promising technique to improving titanium’s poor wear resistance at a relatively lower temperature. Nonetheless, less attention has been paid to the performance of the treated sample at the cathodic potential by CCPN process, mostly on the sample at the floating potential. It has been demonstrated that a nitrogen diffusion layer is formed other than compound layer at the cathodic potential, which is beneficial to improve the bearing-load capacity and adhesion strength between the modified layer and the substrate. In this study, a cathodic cage in combination with pulsed-biased system has been used to realize nitriding of TA1 titanium at the cathodic potential below 660 °C. The influence of pulsed current and treatment time on the resulting surface microstructure and wear performance when sliding against Si3N4 balls were studied. Results showed that with the increasing pulsed current and prolonged processing time, the nitride layer thickness, hardness and roughness also increase. Additionally, although the anti-wear resistance is considerably improved through nitriding treatment compared to untreated TA1 titanium, and there are still differences between the samples prepared under different nitriding parameters. Lastly, the optimum pulsed current and processing time of the CCPN process that provide the best tribological characteristics are determined.

Remarkable enhancement of corrosion resistance and tribological properties of chitosan-MXene based hydrogel coating on the surface of Ti6Al4V alloy

Ti6Al4V alloys have been applied in hard tissue implantation fields. However, their poor wear resistance has been considered as an important factor for aseptic loosening of implants. This limited its application in the biomedical fields. In this work, a chitosan-MXene hydrogel coating was designed and constructed on the surface of Ti6Al4V alloys. The tribological and anticorrosion properties of the hydrogel coating under simulated body fluid (SBF) solution were tested. The results showed that CS-MXene-0.3% hydrogel coating has excellent tribological performance and corrosion resistance properties, with the reduction of the friction coefficient by 78.33% and corrosion inhibition efficiency of 98.79%. This study provides a potential surface modification method for titanium alloy bone implants.

Developing a photothermal anti/deicing fluor‐free composite coating with high wear resistance and liquid impalement resistance based on a new biobased benzoxazine resin and polydopamine‐coated aluminum nitride

AbstractDeveloping photothermal anti/deicing fluor‐free composite coatings with high wear resistance and liquid puncture resistance is an interesting challenge. Herein, a new biomass benzoxazine monomer (C‐d) was synthesized, which was then sprayed on a glass slide, followed by spraying hyperbranched polysiloxane (HSi), polydopamine‐coated micro AlN (P@mAlN), and polydopamine‐coated nano AlN (P@nAlN), successively, to develop a new type of photothermal anti/deicing four‐layer fluor‐free composite coatings with high wear resistance and liquid puncture resistance (C‐d/yHSi/0.4P@2bAlN, y is the mass ratio of HSi to C‐d). Three‐layer composite coatings (C‐d/0.4P@zbAlN, z is the mass ratio of P@mAlN to P@nAlN) and two‐layer composite coatings (C‐d/xP@mAlN, x is the mass ratio of P@mAlN to C‐d) were also prepared to study the influence of compositions on comprehensive properties of coatings. The results show that C‐d/0.4P@zbAlN has significantly longer icing delay time (IDT) than C‐d and C‐d/xP@mAlN coatings but still shows poor wear resistance and liquid puncture resistance. Interestingly, C‐d/yHSi/0.4P@2bAlN coatings have good superhydrophobicity; as y increases, both IDT and wear resistance increase significantly. When y = 0.5, the obtained C‐d/0.5HSi/0.4P@2bAlN coating has the best integrated performance, including high anti‐deicing property (IDT = 627 s), high wear resistance, and liquid puncture resistance as well as good photothermal deicing performance, the ice melts in 343 s under the irradiation with 808 nm infrared light, overcoming the bottleneck of poor wear resistance and liquid puncture resistance of photothermal anti/deicing coatings. Besides, C‐d/0.5HSi/0.4P@2bAlN coating can effectively prevent the adhesion of pollutants and remain superhydrophobicity after soaked in different solutions (pH = 1–10).Highlights A new biomass benzoxazine with good flexibility was synthesized. Photo‐thermal anti/deicing coatings with micro/nanostructured surfaces are built. The fluor‐free coatings have excellent wear resistance and chemical resistance. The mechanism behind was elucidated.

Composition, structure, and wear resistance of (TiZrNbMoTa)CxN1-x high entropy alloy carbonitride coatings prepared by reactive radio-frequency magnetron sputtering

HEN has high hardness and good toughness but a high coefficient of friction and poor wear resistance. In this study, a high hardness, toughness, and wear-resistant HECxN1-x coating was prepared by reactive radio-frequency magnetron sputtering (RFMS) technology. The phase composition, microstructure, mechanical properties, and tribological properties of the HEN and HECxN1-x coatings were investigated. The results show that all coatings have single-phase rock salt structures. The double anion lattice structure of the HECxN1-x coating produces a high lattice distortion effect and grain refinement effect, which realizes the strengthening and hardening of the coating. When the [C]/([C] + [N]) ratio is 0.3, the hardness of the HECxN1-x coating reaches the maximum value of 41.7GPa, and when the [C]/([C] + [N]) ratio is 0.4, the coating toughness reaches the maximum value of 0.91GPa, which are 48 % and 203 % higher than HEN. The self-lubricating effect of supersaturated precipitated amorphous carbon makes the HECxN1-x coating achieve excellent tribological properties. Among them, HEC0.5N0.5 coating has the best tribological properties, its coefficient of friction (COF) is 0.391, which is 148 % lower than that of HEN coating, and the wear rate is reduced to 1/15 of HEN coating, which is one order of magnitude reduction. Introducing the C element based on HEN can effectively solve the problems of high friction coefficient and poor wear resistance of high entropy nitride ceramic coatings.

Additively manufactured high entropy alloy with high wear resistance for biomedical implant

Titanium and its alloys play a vital role as implant materials in orthopedic and dental surgery. However, its poor wear resistance limits its application in the medical field. High entropy alloy (HEA) has high wear resistance due to the combined action of high entropy, lattice distortion, and cocktail effects. In this work, TiFeCrCoNi HEA is prepared by Laser powder bed fusion (LPBF) under the protection of high pure Ar gas. The results show the TiFeCrCoNi HEA has mainly FCC phase and a small amount of Hexagonal and Laves phases. Its microhardness is up to 776.3 ± 21.4 H V and is 2.8 times that of pure Ti. Meanwhile, the HEA has a low friction coefficient of 0.1–0.15, which is attributed to high hardness precipitates and grain refinement. The main wear mechanism of the HEA is oxidation wear, adhesive wear, and abrasive wear. In addition, the TiFeCrCoNi HEA also demonstrates good biocompatibility.

Tribocorrosion and Surface Protection Technology of Titanium Alloys: A Review.

Titanium alloy has the advantages of high specific strength, good corrosion resistance, and biocompatibility and is widely used in marine equipment, biomedicine, aerospace, and other fields. However, the application of titanium alloy in special working conditions shows some shortcomings, such as low hardness and poor wear resistance, which seriously affect the long life and safe and reliable service of the structural parts. Tribocorrosion has been one of the research hotspots in the field of tribology in recent years, and it is one of the essential factors affecting the application of passivated metal in corrosive environments. In this work, the characteristics of the marine and human environments and their critical tribological problems are analyzed, and the research connotation of tribocorrosion of titanium alloy is expounded. The research status of surface protection technology for titanium alloy in marine and biological environments is reviewed, and the development direction and trends in surface engineering of titanium alloy are prospected.

Effect of Electrolyte Concentration and Voltage on the Morphology and Corrosion Resistance of PEO Coated AA6061

Aluminum and its alloys are among the most extensively used materials in aerospace and industrial applications owing to its high specific strength, low density, and high abundance on the earth’s crust. However, low hardness, high tendency to adhesion, high corrosion, and poor wear resistance limits its further application. Surface treatments like electroplating, PVD/CVD, and anodizing are proposed to form a protective coating on the surface of Al and its alloys. Plasma Electrolytic Oxidation (PEO), known as micro-arc oxidation (MAO), emerged as a promising surface coating technique producing high-quality ceramic coating for light metal alloys like Al, Mg, Ti, and their alloys. PEO is similar to conventional anodizing but at a higher voltage exceeding its breakdown voltage, forming plasma discharge. In this study, the PEO of AA6061 was carried out in an AC power source at constant voltage 325-400 V, 1000 Hz, and 80 % duty cycle for 30 min. Silicate-based electrolytes of different concentrations (5-10 g/L) Na2SiO3 and (5-10 g/L) KOH were utilized, maintaining 25-40°C electrolyte temperature. The effect of electrolyte concentration and constant voltage on the coating morphology and its relation to hardness were investigated. Surface morphology, cross-section, elemental distribution, and phase composition were characterized using SEM, EDX, and XRD. Different breakdown voltages were determined for each electrolyte concentration. A lower breakdown voltage was achieved at a higher concentration. Porous with pancake-like structure, crater, and nodular structures were observed with coating thickness ranges from 8.37-87.33µm. α-alumina and Ƴ-alumina peaks were detected in all surface coatings.

A double-layer multifunctional superhydrophobic coating with excellent anti-corrosion performance based on fluorine-free chemicals

Superhydrophobic coatings with micro and nano structures have great potential in a wide spectrum of fields due to their multifunctionality. However, some disadvantages, such as poor wear resistance and containing toxic fluorine substances, greatly limit the practical application of superhydrophobic coatings. To overcome these shortcomings, herein we have prepared a double-layer coating without fluorine which demonstrates superhydrophobicity with a contact angle of 159.5°. The bottom layer of KH560-graphene oxide (GO)/epoxy (EP) and the surface layer of hydrophobic hexadecyltrimethoxysilane modified SiO2 (HDTMS-SiO2) is prepared by scraping and spraying, respectively. The bottom layer of KH560-GO/EP effectively promotes the adhesion of the top SiO2 layer and the coating maintains a superhydrophobic state even after sandpaper sanding, compressive studies and sand impact. In addition, the coating also has superior self-cleaning, anti-fouling, and anti-icing abilities, and it takes 157 s for it to ice up. More importantly, the superhydrophobic coating also exhibits outstanding corrosion resistance due to the synergistic effect of well-dispersed GO and hydrophobic surfaces. This work has demonstrated the great potential of fabricating composite superhydrophobic coatings via artificial architecture design for diversified applications.

Study on the technology of surface strengthening Ti–6Al–4V alloy by near-dry multi-flow channel electrode electrical discharge machining

Titanium alloy has excellent performance and wide application prospects in the aerospace, energy, chemical industry, and other areas. However, low hardness and poor wear resistance severely limit the application range of titanium alloys. Therefore, in the present research, multi-flow channel electrode and gas-liquid atomization medium are used for surface strengthening of Ti–6Al–4V alloy by electrical discharge machining (EDM). Benefiting from the multi-flow channel electrode, the gas-liquid atomization medium passes into the discharge gap uniformly. Under the environment of transient high-temperature and high-pressure generated by discharge, the ionized element N and molten titanium in the atomizing medium are induced to undergo in-situ synthesis reactions and generate a nitride reinforcement layer. Influence parameters such as peak current, pulse on time (Ton), and pulse off time (Toff) on the surface characteristics are optimized through single-factor experiments. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) are adopted to investigate the hardness and wear resistance characteristics of the strengthening surface. The results indicate that a continuous and uniform reinforcement layer with fewer defects can be obtained. TiN and other hard phases are observed in the strengthened surface. The hardness of the strengthening layer is about 3–5 times as much as that of the substrate, and the wear resistance is increased by more than 40 %. Electrochemical analysis shows that the corrosion tendency of the strengthened layer decreased by 72 % compared to that of the substrate.

Simultaneous fabrication of Ti-MoS2 self-lubricating coatings and gradient structures to improve the wear resistance of AZ91D alloys

Magnesium alloys are essential for lightweight manufacturing. Nevertheless, defects such as low hardness and poor wear resistance severely restrict their further applications. Ultrasonic impact treatment (UIT) was used to simultaneously fabricate surface Ti-MoS2 self-lubricating coatings and interior gradient structures on AZ91D magnesium alloy for the first time. The surface morphology and microstructure were investigated, the tribological properties were evaluated at various normal loads, and the formation principles and anti-wear mechanisms of coatings and gradient structures were revealed. The findings indicate that the coatings present a particle-stacking microstructure. The gradient structures were characterized by grain, dislocation, and hardness distribution from greater to lesser along the depth direction. At all loads, the UIT samples exhibited superior anti-wear properties. Compared to untreated samples, the UIT sample's wear volume at 5 N, 15 N, and 25 N loads was reduced by 89.78 %, 84.23 %, and 43.88 %, respectively. The wear surface analysis indicates that the Ti-MoS2 coatings effectively enhance the lubricity of friction surfaces. Additionally, gradient structure works when the coatings fail and reduces the shear deformation, further reducing wear. This work presents a new method for fabricating simultaneously surface coatings and interior gradient structures using UIT, contributing to improving the anti-wear properties of magnesium alloys and enhancing their utilization in lightweight manufacturing fields.

Wear resistance mechanism of graphene/copper composite foils with bimodal structure

Copper foils have a wide range of applications in modern industry. However, their wider utilization is restricted by the poor wear resistance of pure copper. Therefore, improving the abrasion resistance of copper foils is essential for their application in various scenarios. In this study, controlling the parameters of pulsed electrodeposition and incorporating graphene, pure copper foil, and graphene/copper (Gr/Cu) composite foil with distinct microstructures were successfully prepared. Gr/Cu composite foil with bimodal structures exhibits excellent wear resistance, with a coefficient of friction (COF) 0.2 lower than pure Cu foil and a wear rate of only 61.4% of pure Cu foil. We investigated the effects of bimodal structure and graphene on the wear resistance mechanism of Gr/Cu composite foil. The presence of ultrafine grains (UFG), fine grains (FG), and coarse grains (CG) in the bimodal structure enhances the wear resistance of the Gr/Cu composite foil, by resisting crack initiation and propagation. In addition, graphene provides lubrication, and stress dispersion and prevents abrasive particles from entering the foil surface, thus preventing delamination and spalling, which further improves wear resistance. This research demonstrates the potential synergistic effect of bimodal structures and graphene to improve the wear resistance of copper foils, which is promising to provide more durable solutions for a wide range of industries.

High wear resistance of uniform nitriding titanium composites fabricated by in-situ laser powder bed fusion

Laser powder bed fusion (LPBF) supplies a new method for titanium matrix composites (TMCs) that are difficult to process using traditional production. Aiming at the current LPBF-printed pure titanium with low hardness and poor wear resistance, this paper proposes an innovative method of laser in-situ synthesis of uniform nitriding TMCs under the interaction of Ar + 0/5/10/15 % N2 with Ti powder in the LPBF process. It is shown that the forming quality can be modulated by the laser energy density and N2 concentration. TiN was in-situ synthesized in more than 10 % N2. Moreover, the hardness and wear resistance of LPBF-ed TMCs increased with rising N2 concentration. The friction coefficient decreased from 0.39 under Ar to 0.32 of 15 % N2, and the wear rate decreased by 70 %. Besides, this study provides a reference for in-situ synthesis of gradient TMCs with high hardness and wear resistance on the surface, while the inner is ductile.

An Ultrahigh Power Density and Ultralow Wear GaN-Based Tribovoltaic Nanogenerator for Sliding Ball Bearing as Self-Powered Wireless Sensor Node.

The tribovoltaic effect is regarded as a newly discovered semiconductor effect for mechanical-to-electrical energy conversion. However, tribovoltaic nanogenerators (TVNGs) are widely limited by low output power and poor wear resistance for device integration and application. Here, this work invents a TVNG using a ball-on-disk structure composed of gallium nitride (GaN) and steel ball. It exhibits an open-circuit voltage exceeding 130V and an ultrahigh normalized average power density of 24.6kW m-2 Hz-1 , which is a 282-fold improvement compared to previous works. Meanwhile, this TVNG reaches an ultralow wear rate of 5×10-7 mm3 N-1 m-1 at a maximum contact pressure of 906.6MPa, surpassing the TVNG composed of Si by three orders of magnitude due to the local concentrated injection of frictional energy. Based on the TVNG, this work constructs the first tribovoltaic bearing and achieves sensing signal transmission within 16 s (300 rpm) by integrating a management circuit, a transmission module, a relay, and receiving terminals, which enables the monitoring of ambient pressure and temperature. This work realizes a GaN-based TVNG with high-performance and low wear simultaneously, demonstrating great potential for intelligent components and self-powered sensor nodes in the industrial Internet of Things.

Role of multi-walled carbon nanotube particles on the wear behaviour of vacuum hot pressed Mg-AZ91 composite

The demerit of Mg-AZ91 alloy is poor wear resistance. In order to increase the wear resistance and decrease the CoF, MWCNT is reinforced in various wt% (0.5, 1, & 1.5) into Mg-AZ91 by a vacuum hot press technique. The OM image of the specimens shows the strong metallurgical bonding between matrix material, uniform dispersion of MWCNT for 0.5 and 1 wt% composites and agglomeration of MWCNT for 1.5 wt% composite. XRD analysis confirms MWCNT presence and peak shift towards a higher angle in the composites. MWCNT reinforced 1 wt% composite has exhibited the highest hardness values of 97.90 HV0.3, good wear resistance (wear rate = 3.28 × 10-5 g/m) due to the strengthening by grain size reduction and a low CoF value of 0.32 due to the self-lubrication effect of MWCNT. SEM investigation confirms that surface fatigue is the dominant wear mechanism in all specimens.

Enhancing mechanical and functional properties of LM25 alloy through squeeze cast hybrid nanocomposite incorporating breadfruit seed husk ash and graphite nanoparticles

ABSTRACT In this research, effective utilization of agro waste breadfruit seed husk ash particle (SHA) as reinforcement purpose in LM25 alloy matrix enhanced with the inclusions of 3, 6, and 9wt% of graphite (Gr) nanoparticle (50nm) via squeeze cast liquid processing executed with 200MPa applied compressive pressure. This developed cast examined LM25 alloy and its composites for density, percentage of porosity, microstructure, ultimate tensile strength, abrasion, and corrosion behaviour. From the experimental result, the LM25/10wt% SHA/9wt% Gr hybrid nanocomposite has low density (2.554g/cc), an excellent ultimate tensile strength of (181±1.8 MPa), superior abrasion resistance (0.332mg/m) under 40N load at 0.75m/sec, and good corrosion resistance (0.00382mm/year) compared to cast LM25 alloy. The inclusions of SHA and Gr proved their presence in LM25 alloy has good mechanical strength and maximum abrasion and corrosion resistance to overcome the drawbacks of conventional stir-casted LM25 alloy, which is poor wear resistance.

Preparation and performance of Ti/Ti-DLC composite coatings for precision glass molding

Precision glass molding (PGM) is an efficient process used for batch manufacturing of high-precision glass optical elements. In this process, nickel phosphide (Ni–P) alloy is commonly utilized as a mold material due to its superior turning properties. However, the Ni–P mold suffers from issues such as diffusion of phosphorus elements, poor wear resistance, and easy peeling of the DLC coating during molding. To address these problems, the current study proposes enhancing the molding performance of mold by depositing a composite coating layer of Ti/Ti-DLC onto the surface of Ni–P using the filtered cathodic vacuum arc technology (FCVA). The effects of different flow rates of C2H2 on Ti-DLC coatings were analyzed in terms of composition, microstructure, mechanical, tribological, and molding properties. The results revealed that as the C2H2 flow rate increased, the Ti content of coatings decreased from 13.56 to 2.17 at.%. Additionally, the film microstructure transformed from TiC polycrystalline composite films to nanocrystalline amorphous composite films and finally to amorphous films. The Ti-DLC coatings with a nanocrystalline composite structure exhibited excellent overall performance when Ti content is 7.75 at.%. These coatings are suitable as protective coatings for microstructured array mold and demonstrate good stability at a molding temperature of 500 °C.

Chemically Functionalized Graphene–Boron Nitride/Polypropylene Nanocomposites with Enhanced Nanomechanical and Anti-wear Properties

Polymers are soft materials with large molecular chains, which are softened during frictional wear, leading to bulk detachment of materials and poor wear resistance in addition to their low mechanical strength and hardness. This study developed polypropylene nanocomposites containing hydrothermal assembled graphene and boron nitride (BN@GNs) with good mechanical properties and wear resistance. To ensure good dispersion of the nanoparticles in the polypropylene (PP) matrix, they were functionalized and preparation of masterbatch using polypropylene maleic anhydride (PPMA) was adopted, while the polymer nanocomposites for this study were developed via melt compounding. The addition of the nanoparticles in the PP matrix promoted its wear resistance as all the developed nanocomposites showed a low coefficient of friction (CoF). The wear rate of the nanocomposites was dramatically reduced to a minimum of 2.05 × 10−4 mm3/Nm for the PP/3wt%BN@GNs nanocomposite from around 24.9 × 10−4 mm3/Nm for the pure PP. The nanoindentation test results of the nanocomposites also revealed improvement in their nanomechanical characteristics. For instance, PP/3wt%BN@GNs nanocomposite showed an ideal increase of about 124% nano-hardness and 65.7% nano-elastic modulus when compared to pure PP. In comparison to pure PP, all of the developed nanocomposites displayed lower nano-percentage creep and nanoindenter’s tip penetration depth, which suggest greater plastic deformation resistance.

Effects of thermal cycling treatment on load bearing and friction behavior of SiCp/A356 composites

During bench tests and actual service, the Al-MMC (metal matrix composite) brake discs used in urban rail transit vehicles experienced problems such as poor wear resistance, compromising the brake discs' stability and safety. While braking, the brake disc material will bear the thermal cycling loads, leading to a certain degree of degradation in the material's performance. In this study, the degradation of the material's performance by the thermal cycling treatment was investigated. The results showed that all material performance degraded to some extent after thermal cycling treatment, with a strong correlation with cycling temperature. The degradation of material performance was caused by a combination of matrix mechanical damage and interface damage. At the same time, the tribological performance of the material also decreased to some extent. The main effect of thermal cycling treatment on tribological performance was its effect on material performance. The increase of hard particles in the abrasive debris resulting from the mechanical damage of the material and the aggravation of the dynamic changes in the TBL (third body layer) were the basic reasons for the surface scratches. The results further help to explore the application of Al-MMCs in high-temperature and long-term service.