Abrasive Research Articles

Study on shot peening strengthening 42CrMoA steel and its fretting wear properties

In order to improve the tribological properties of 42CrMoA steel, it was shot peened using different parameters. The surface morphology, residual stresses, hardness, and micromotor properties of the treated specimens were thoroughly evaluated. The results showed that it led to substantial plastic deformation, increased surface roughness, grain refinement, and introduction of residual compressive stresses. In addition, a significant increase in microhardness and depth of hardened layers on the specimen surfaces was observed. Furthermore, a positive correlation between the effect of the shot peening process and the peening duration was observed. As revealed by the investigation, the shot peening process not only advances the wear resistance of the specimens but also leads to a reduced wear volume compared to untreated specimens. Furthermore, this treatment triggers a shift in the wear mechanism from the predominant occurrence of severe adhesive wear, fatigue wear, and abrasive wear in untreated specimens to a predominant mode of abrasive wear, accompanied by a minor occurrence of adhesive wear.

Microstructure and Tribological Properties of WC/Ni-MoS2 Titanium-Based Composite Coating on TC4

To improve the mechanical properties of a TC4 surface, TC4 + Ni-MoS2 + xWC (x = 5%, 10% and 15% wt.%) composite coatings were prepared by the coaxial feeding laser cladding technique, and the effect of the WC content on the microstructure and tribological properties of the coatings were investigated using multiple characterization methods. The results indicated that increasing the WC content negatively impacted the forming quality of the coating, but did not change the coating phase which predominantly comprised Ti2Ni, Ti2S, TiC, matrix β-Ti and residual WC. With the addition of WC, TiC exhibited an increase in both quantity and particle size, accompanied by a transition in growth morphology from spherical to petal-like. MoS2 completely dissolved in all coatings and the S element provided by it effectively synthesized a strip-like phase Ti2S which presented a morphology similar to the lubricating phase TiS in the Ti-based melt pool system. The microhardness and wear-resistance of all the coatings were higher than that of TC4 and gradually improved with the addition of WC, which indicated that raising the WC content was conducive to enhancing the mechanical properties of the coatings. The friction coefficient of TC4 was lower than that of the three WC content coatings, indicating that Ti2S was not the lubricating phase. The wear mechanism of all coatings was abrasive wear.

Preparation and Wear Resistance of Porous TC4 Titanium Alloy Micro‐arc Oxidation Coating Produced by Selective Laser Melting

The porous TC4 titanium alloy prepared by selective laser melting (SLM) is modified by micro‐arc oxidation (MAO) technology. By introducing active elements such as calcium (Ca) and phosphorus (P) into the electrolyte, a wear‐resistant active coating is constructed on the surface of porous TC4. The effects of MAO process parameters on the surface morphology and wear resistance of the coating are discussed. The results show that the thickness and adhesion of the coating increase with the increase of the first‐stage oxidation time, and decrease with the increase of the second‐stage oxidation time. In all processes, the MAO‐2 coating has better surface morphology and performance, with a median pore size of 0.51 μm and a binding force of 18 N. XPS analysis confirms that the coating is mainly composed of TiO2, Ca2P2O7, and Ca(PO3)2 phases. The study of tribological behavior shows that the wear form of the substrate is abrasive wear, while the wear form of the coating is adhesive wear. The friction coefficient of the coating is significantly lower than that of the substrate, and the wear resistance is better. This study provides an effective way to optimize the surface properties of porous TC4 titanium alloy.

Investigation of the synergetic effect of oleophilic textured surfaces and MoS2 at different loads on the tribological performance of Ti64 alloy

In this research study, surface modification of Ti64 alloy was carried out using laser surface texturing (LST). The investigation aims to explore the effects of loads, oleophilic textured surfaces, and MoS2 as a solid lubricant on the friction and wear reduction of Ti64 alloy and AISI 52100 steel tribo-pairs. Three types of LST textures (Circular, triangular, and square textures) were created on the Ti64 alloy. Subsequently, tribological experiments were performed using a ball-on-disc universal tribometer at loads of 5, 10, and 15N with a 15 Hz frequency. The worn surface was analyzed using various methods, including optical microscopy, 3D-profilometer, FESEM, EDAX analysis, and Raman spectroscopy. The study compared the coefficient of friction (COF) and wear behavior of non-textured surfaces (NTS) with those of textured surfaces (TS) under both dry sliding conditions (DSC) and lubricated sliding conditions (LSC). The results demonstrated a significant reduction in the COF and wear coefficients on the TS. Specifically, the circular texture (CiT) exhibited a remarkable reduction of 39.3%, 63.83%, and 83.6% in wear coefficients compared to the NTS tested under DSC and LSC (using pure PAO-4 and PAO-4 + 1% wt MoS2) with sliding load of 15N. DSC showed abrasion, adhesion, and delamination wear, while LSC displayed mild adhesion, delamination, and tribo-layer formation on NTS and TS. The analysis indicated that the use of LST and solid lubricant nanoparticles on a Ti64 alloy would result in improved service life and better endurance in cutting tools and tribo-mating parts.

Effect of surface area on the wear properties of Al-based automotive alloy and the role of Si at eutectic level

The efficiency of an engine material is closely correlated with its surface area. In order to investigate wear properties, effect of surface contact area as well as silicon addition at the eutectic level of Al-Cu-Mg alloy has been studied. This test is performed under room atmosphere and dry sliding conditions using a standard pin-on-disk apparatus. Weight reduction method is adopted to measure the wear rate in microns to get more accurate results. A load varying from of 5 to 50 N and a constant sliding speed of 0.77 ms−1 are maintained throughout the test. The test results show that a lower contact surface area has a negative impact on the wear properties having higher wear rate, while the coefficient of friction of the alloy and Si addition into the alloy improve the properties to some extent. Reduction of the contact surface area increases the unit pressure and decreased material volume causes softening of the alloy matrix, resulting in a higher wear rate and coefficient of friction. The Si addition offers such an improvement mostly for an increase in strength via the Si-rich intermetallic formation. A microstructural study confirms a lower abrasive wear with a minor plastic deformation on the worn surfaces of Si added alloy and wear with higher contact surface. The Si-added alloys contain the fine and strong Si-rich intermetallic, which are responsible for such a smooth worn surface.

Effects of fatigue load characteristics on bending tribo-corrosion-fatigue damage of steel wire ropes in seawater and pure water

Tribo-corrosion-fatigue coupling damage greatly affects the service safety of wire rope. A self-made test rig was employed to investigate the influences of fatigue load characteristics (amplitude, stress ratio, maximum) on bending tribo-corrosion-fatigue damage of wire ropes. The tribological properties and electrochemical corrosion of the wire ropes, and the coupling damage and mechanisms were discussed in detail. Results indicate a lower friction coefficient between wire ropes in artificial seawater. The main wear mechanisms in seawater are adhesive wear, fatigue wear, oxidation wear and corrosion wear as compared to abrasive wear, adhesive wear, oxidation wear and fatigue wear in pure water. Lower stress ratios amplify corrosion and adhesive wear. Fatigue fractures are mainly ductile, with stress ratio being a significant factor. Tribo-corrosion-fatigue coupling exacerbates damage in contact ropes compared to fatigue ropes. Seawater increases fatigue rope damage but reduces contact rope damage. Higher fatigue load amplitude and maximum value, and lower stress ratios, increase friction coefficient, deformation, volume loss, wire breakage, and decrease corrosion resistance. These findings provide essential data for assessing wire rope service life under seawater corrosion conditions and ensuring offshore drilling safety.

Effect of graphene content on the tribological and corrosion behavior of high-speed-laser-clad high-entropy-alloy composite coatings

To repair oil drill pipe joints that have failed owing to dry wear and tribocorrosion, graphene-reinforced CoCrFeMo0.5NiTi0.5 high-entropy alloy composite coatings (HEACCs) were developed through high-speed laser cladding. The HEACC containing 1.5 wt% graphene exhibited dry wear and tribocorrosion rates that were 59.18 % and 32.20 % of those observed in the high-entropy alloy coating, respectively. The HEACC exhibited a corrosion current density of 2.475 × 10−7 A/cm2. The HEACC containing 1.5 wt% graphene underwent progressive damage during dry wear owing to the combined effects of abrasive wear, which created furrows; adhesive wear, which led to flaking; and oxidative wear, which formed oxide layers. During tribocorrosion, chloride ions exacerbated surface damage caused by hard abrasives and asperities, intensifying corrosive–abrasive wear interactions.

Microstructure evolution and tribological properties over a wide temperature range of Ni-based composite coatings with Ti3AlC2 addition

Ni60A alloy powders doped with varying concentrations (0, 10 wt% and 20 wt%) of Ti3AlC2 MAX phase were coated on S31008 NiCr stainless steel substrate using atmosphere plasma spraying technique in this work. Comparative investigation was conducted to examine the effects of Ti3AlC2 additions on the microstructure evolution, microhardness, and wide temperature range (room temperature to 800 oC) tribological performance of the composite coatings. The findings demonstrated that the composite coatings were composed of γ-Ni, intermetallic hard metal borides, Ti3AlC2 and TiC phases, without any noticeable oxide phases. The 20 wt% Ti3AlC2 additions to the Ni60A alloy coating exhibited minimum imperfections in microstructure with a porosity drop of 65.8 %, and the highest microhardness which was enhanced by 64 % to 924 HV0.515. After introducing of Ti3AlC2, the coefficient of friction decreased and appeared to distinguish itself by remaining minimal and stable at low-medium temperatures compared with an increase of more than 70 % at high temperatures. Ni60A-10 wt% Ti3AlC2 coating resulted in the lowest friction coefficient of approximately 0.45 from room temperature to 400 oC and it peaked to 0.78 at 800 oC, reducing by 19.6 % and 6 % compared to non-composite coating, respectively. The wear resistance of the composite coating was considerably improved with the increment of Ti3AlC2, and the coating with 20 wt% Ti3AlC2 showed the most significant reduction in wear rate: 18.5 % at room temperature, 45.2 % at 200 oC, 37.2 % at 400 oC, 60 % at 600 oC, 90.8 % at 800 oC. The lubricate layered Ti3AlC2 phases and the tribo-oxide film predominate composed of derivative NiO, Cr2O3 Al2O3 and TiO2 played a critical role in antifriction and wear resistance. The wear mechanisms were accordingly conducted as abrasion and adhesion wear at low-medium temperature and transferred into tribo-oxidation wear at elevated temperature.

Effects of Y2O3 Content on the Microstructure and Tribological Properties of WC-Reinforced Ti-Based Coatings on TC4 Surfaces

To extend the safety service life of aviation TC4 alloy, the composite coatings of TC4 + Ni-MoS2 + WC + xY2O3 (x = 0, 1, 2, 3, 4 wt.%) were prepared on TC4 by coaxial powder feeding laser cladding technology. The results showed that all the coatings had the same generated phases which mainly consisted of TiC, Ti2Ni, Ti2S, matrix β-Ti, and unfused residual WC. Y2O3 formed co-dependent growth relationships with TiC, Ti2S, and Ti2Ni. Meanwhile, TiC-Ti2S, TiC-Ti2Ni, and Ti2S-Ti2Ni coherent composite structure phases were effectively synthesized in all the coatings. With the increase in the Y2O3 content, the exposed area of the matrix increased and other phases refined progressively. When the Y2O3 content in the coatings were 3 and 4 wt.%, the degree of phase refinement in the coatings was consistent and the phases grew along grain boundaries, but microstructure segregated in the 4 wt.% Y2O3 coating. The microhardness of all the coatings was higher than that of TC4 and decreased with the increase in the Y2O3 content. Higher friction coefficients and lower wear rates both appeared in all the coatings than in the substrate, and they presented a trend of decreased first and then increased with the addition of Y2O3, in which the 3 wt.% Y2O3 coating had the lowest friction coefficient and optimal wear resistance. The research found that the Y2O3 could not change the types of phases in the coatings and could serve as a heterogeneous nucleation center for the refinement of the TiC-Ti2S-Ti2Ni coherent structure phase. Meanwhile, except for the matrix phase, Y2O3 could attract other phases to pinning on the grain boundaries of the coatings. The content of Y2O3 was negatively correlated with the hardness and wear resistance of the coating and it had the optimal tribological properties with the moderate amount of Y2O3. The wear mechanism of all coatings was abrasive wear.

Structural evolution of ultrahigh molecular weight polyethylene under sliding friction in seawater

AbstractUltrahigh molecular weight polyethylene (UHMWPE) is suitable for tribological applications in various environments because of its advantageous characteristics, including its high‐impact strength, excellent resistance against wear and corrosion, and self‐lubricating properties. However, the tribological behavior of UHMWPE under seawater lubrication is still poorly understood. In this study, the wear mechanisms of UHMWPE in seawater environment were elucidated by examining its morphology and structural evolution during sliding friction. The tribological properties of UHMWPE were significantly affected by the sliding speed in seawater. At low sliding speeds, no long‐strip structures were observed on the worn UHMWPE surface. However, as the sliding speed was increased, prominent convex long‐strip structures appeared and became more densely distributed with time. The molecular chains in the amorphous region of UHMWPE stretched along the sliding direction under stress. In the crystalline region, molecular orientation, and lamellar slip were accompanied by molecular conformational transformations. During the initial stage of sliding friction, UHMWPE mainly exhibited adhesive wear caused by plastic deformation. Subsequently, the wear mechanism of UHMWPE gradually changed from adhesive wear to a combination of adhesive and abrasive wear, and its wear intensified over time.

A comprehensive study on dry sliding wear and in-vitro degradation of AZ31 composite with 6 wt% Sn and 1.5 wt% TiO2 fabricated by stir casting

Abstract This experimental study investigates the dry sliding wear behaviour of novel AZ31 composite with 6 wt% Sn and 1.5 wt% TiO2 samples, focusing on the influence of sliding distance and normal load. Additionally, the research examines degradation rates during a 120-hour immersion period in simulated body fluid (SBF). The wear volume loss increased significantly with higher loads and longer sliding distances, showing a 142% rise from 1000 m to 2000 m and 76% from 2000 m to 3000 m under a 5 N load, peaking at a 25 N load over 5000 m. The specific wear rate dropped by 39% from 5 N to 15 N but increased with distance due to thermal softening, while the coefficient of friction decreased from 0.284 at 1000 m to 0.213 at 5000 m under 5 N. FESEM analysis revealed a transition from abrasive to delamination wear, with a protective oxide layer forming during sliding. Sn in the composite formed hard Mg2Sn intermetallic compounds, affecting crack formation and propagation under higher loads. Wear debris analysis showed both abrasive and delamination wear mechanisms, highlighting the protective role of the oxide layer. The degradation rate increased rapidly during the initial immersion stage in simulated body fluid (SBF), reaching 15.9 mm year−1 after 24 h, and then stabilizing after 48 h. Hydrogen evolution rose sharply from 0.28 ml cm−12 at 2 h to 7.6 ml cm−12 within 24 h, with a 92% increase by 48 h and an additional 38% increase from 48 to 72 h. Post-immersion FESEM analysis showed corroded surfaces with protective layers, cracks, and pitting corrosion. Magnesium hydroxide (Mg(OH)2) and hydroxyapatite played crucial roles in inhibiting corrosion. This analysis provides insights into the wear, and degradation dynamics of the AZ31-6Sn/1.5TiO2 composite, with implications for engineering applications and the development of biodegradable implants in biomedical fields.

Friction and Wear Mechanics of Fe-Based PM Pad Paired with Carbon Fiber-Reinforced Silicon Carbide (C/C-SiC) Disk Under High-Speed Braking

Powder metallurgy (PM) brake pads pair with carbon fiber-reinforced silicon carbide (C/C-SiC) brake disk have been considered as one of the potential candidates for high-speed train applications. In this work, the braking test for iron-based PM (Fe-PM) pads paired with C/C-SiC brake disk at high speeds was conducted on a full-scale flywheel braking dynamometer. With the increasing of initial brake speed (IBS) to 380 km/h, the mean coefficient of friction (µm) gradually decreased, while the wear rate (Wr) of pad got significant increased. The wear pattern of the Fe-PM pad transitioned from abrasive and adhesive wear to oxidative wear with the increasing of IBS, explaining the variations in µm and Wr. Throughout the braking process, wear debris from Fe-PM pad tended to accumulate, forming a dense transfer film (TF) on the C/C-SiC disk. This TF cracked and peeled off due to thermal stress during the braking process. However, analysis of the interior side of the TF revealed that the peeling only caused slight exfoliation of carbon fibers on the surface of the C/C-SiC disk.

Process optimization and tribological behavior of Ti-48Al-2Cr-2Nb prepared by selective electron beam melting

Selective electron beam melting (SEBM) technology was utilized to fabricate TiAl alloys which possess low density and excellent high-temperature performance, to achieve lightweight design of automotive engines. The forming process of Ti-48Al-2Cr-2Nb was systematically optimized, and found that the microstructure of TiAl formed by SEBM consisted of a layer of alternating γ-band structure and duplex-like structure. As the energy density increases, grain coarsening, proportion increasing of high angle grain boundaries, and anisotropy strengthening occur successively. The forming quality of TiAl reaches its peak at an energy density of 22.5 J/mm3, at which point its mechanical properties and wear resistance also perform the best. Subsequently, in-depth friction experiments at high and room temperatures were conducted, and it was found that at room temperature, as the load increased, the friction coefficient of the samples decreased and the wear rate increased. In addition, the friction coefficient decreases from 0.54 to 0.44, while the wear rate increases from 19.90×10−5 mm3/(N·m) to 25.97×10−5 mm3/(N·m). At this point, abrasive and adhesive wear were the main wear mechanism. Under high temperature conditions, the wear mechanism of the substrate is mainly abrasive wear, adhesive wear, and oxidative wear. And the friction coefficient decreases from 0.69 to 0.49. At lower temperatures, the detached debris was filled and solidified on the wear marks under the action of the friction ring, forming a hardened layer called “enamel”, which can alleviate the negative effects of wear. Under the influence of extreme high temperature environment, the unworn surface forms a light blue oxide film due to rapid oxidation, known as the “burning blue” phenomenon. Along with the high-temperature oxidation phenomenon confirmed by EDS, the oxide layer is more prone to peeling off and forming debris. In addition, melting softening occurs inside the annular wear scar, which increases the amount of deformation under external force, ultimately leading to a significant increase in wear.

Analysis of abrasion wear in particle storage and valve subsystem for falling particle concentrating solar power

Solar energy capture and storage using falling solid particles are being explored for cost-effective next generation concentrating solar power systems. A critical consideration in this technology is the abrasion wear caused by the sliding of the particles under varying speed and pressure over component surfaces. This study presents computational modeling of a subsystem comprising a particle storage bin discharging through a flow control valve that is prone to abrasive wear. The effects of several geometric parameters are systematically evaluated for their impact on spatial and temporal abrasion rates in the storage bin, the control valve, and the valve housing. The findings provide insights into the locations most susceptible to abrasion, and the use of targeted abrasion mitigation coatings is illustrated.

Improving the lubricating performance of poly-alpha-olefin base oil using SnO2 nanosized-additives

The majority of previous studies have been focused on the thermal properties of SnO2 nanofluids. In order to understand the lubricating performance of SnO2 nanoparticles as additives, the current study investigates the effects of the addition of SnO2 nanoparticles on the tribological properties of poly-alpha-olefin 6 base oil. The dual-step method is utilized to disperse the SnO2 nanoparticles in base oil with oleic acid as surfactant. The shape and size of SnO2 nanoparticles are confirmed by transmission electron microscopy, and the dispersion stability of SnO2 nanoparticles is examined by dynamic light scattering tests. The lubricating properties of SnO2 nanofluids are explored on a universal mechanical tribometer with a ball-on-plate reciprocating sliding configuration. It is found that the SnO2 nanofluids show good stability and dispersibility. The addition of SnO2 nanoparticles decreases the friction and wear for steel-steel tribo-pairs. The positive effects on friction and wear reductions become more significant with increasing concentrations of SnO2 nanoparticles. In this work, nanofluids containing the 5wt% SnO2 nanoparticles and 5wt% oleic acid is considered as the optimum composition, which shows the best lubricating performance with the reductions of 13.8% in coefficient of friction and 41.4% in wear volume loss. After observing the wear tracks by scanning electron microscopy, energy dispersive spectrometer and a white-light interferometer, it is shown that the wear mechanisms are dominated by abrasive wear and adhesive wear. The enhancement in tribological properties of base oil is attributed to the formation of SnO2 tribo-film and oleic acid tribo-layer which reduces the shearing resistance, separates the mating areas and withstands the loads. The findings obtained in this study can be used as references in the development of high-performance nanofluids.

Evaluation of wear resistance of CrN, CrAlN, and TiAlN coatings deposited by multi-arc ion plating on spinning die of Cr12MoV

Abstract This study successfully deposited CrN, CrAlN, and TiAlN coatings on the surface of Cr12MoV substrate using multi-arc ion plating (MAIP). The influence of phase composition and surface morphology on the hardness, adhesion strength, friction performance, and wear mechanisms of these coatings was investigated, with a comparative analysis of their wear resistance. Nanoindentation results revealed that the hardness (H) of CrN, CrAlN, and TiAlN coatings increased by 70.37%, 74.97%, and 75.64%, respectively, compared to the substrate. The hardness (H) and elastic modulus (E) were found to be positively correlated. CrAlN demonstrated superior resistance to deformation, reflected in its higher H/E and H 3 /E 2 radios compared to the CrN and TiAlN. Adhesion tests showed that CrAlN had the strongest adhesion strength to the substrate, with an adhesion force of 81.55 N, representing a 14.78% and 8.46% improvement over CrN and TiAlN, respectively. Friction and wear tests identified CrAlN as having the lowest friction coefficient (0.389), attributed to its high hardness and strong adhesion. The wear mechanisms of CrAlN observed were primarily mild abrasive wear, oxidative wear, and adhesive wear. In comparison, CrN and TiAlN coatings exhibited higher friction coefficients of 0.424 and 0.391, respectively, due to their lower hardness and adhesion, which led to more severe oxidative and abrasive wear. Additionally, the TiAlN coating showed signs of brittle failure in wear scars, likely due to the formation of Al2O3 oxides during wear.

The microhardness, morphology and tribological property of TC4 subjected to machine hammer peening

Ti alloy has become an indispensable material in harsh working environments due to its excellent wear resistance, corrosion resistance and impact resistance. These environments place stringent requirements on the fatigue life, friction and wear, and surface strength of materials. Therefore, this study aims to deeply explore the surface mechanical properties of Ti-6Al-4V (TC4) alloy after machine hammer peening (MHP) treatment. By conducting experiments on TC4 alloys treated with different hammering energies, the changes in surface hardness, morphology, roughness, tensile properties, and friction properties were analyzed, and the strengthening mechanism of MHP was discussed. Experimental results show that MHP treatment can effectively improve the surface properties of TC4. With the increase of hammer energy, due to the double-sided hammering of the plate, the microhardness first increases, then decreases, and then rises again. The tensile strength and yield strength of the sample increase slightly, but the elongation at break decreases. The surface roughness of the sample increases first and then decreases. Similarly, after MHP treatment, the wear resistance of the samples increased, the friction coefficient decreased, and the wear amount and surface height difference showed a trend of first increasing and then decreasing. The wear mechanism mainly included adhesive wear, abrasive wear and fatigue wear.

Tribological performance of ZrO2 nanoparticles as friction and wear reduction additives in aviation lubricant

Abstract High-performance aircraft engines require superior aviation oils to enhance their lubricating performance and prolong service life. Addition of nano-sized ceramic particles has been considered as a useful way to improve the tribological performance of base fluids. Up to now, few previous studies focused on the tribological properties of ZrO2 nanoparticles in aviation oil. The current study dispersed ZrO2 nanoparticles into PAO20 aviation base oil as lubricant additives. A dual-step method comprised of physical blending and ultrasonic dispersing was applied in the preparation of ZrO2 nanofluids. Oleic acid was utilized as surfactant to enhance the stability of ZrO2 nanofluids. Ball-on-plate reciprocating sliding wear tests were conducted to obtain the coefficient of friction and wear volumes. It was found that the PAO20 base oil produced the highest coefficient of friction of 0.278 and wear volumes of 2.305╳10-2 mm3. 5wt% ZrO2 nanofluids with 5wt% oleic acid showed the best lubricating performance. The coefficient of friction was reduced by 31.29%, and wear volume was reduced by 42.95%. In the examination of wear tracks, a physically embedded tribo-layer of ZrO2 nanoparticles and an oleic acid tribo-film with low shearing resistance were formed, which lowered the friction, and protected the mating surfaces against abrasive and adhesive wear. The results obtained in this study have applicable values in the development of high-performance aviation lubricants.

Microstructure and wear property of (TiN + NbC) double ceramic phase-reinforced in FeCrNiCoAl high-entropy alloy coating fabricated by laser cladding

This study delves into the influence of TiN and NbC ceramic particles on the phase structure, grain organization, microhardness, and wear resistance of FeCoNiCrAl High-Entropy Alloy (HEA) composite coatings produced through laser cladding. The integration of ceramic particles induced a dual BCC solid-solution phase structure (B2+BCC), with the formation of a TiNb phase upon the melting and interaction of TiN and NbC in the melt pool. The ceramic particles significantly modified the grain structure of the HEA coatings, disrupting the Columnar-to-Equiaxed Transition (CET) and favoring the emergence of equiaxed grains. The TiN particles induced a substantial refinement of grain size, albeit unevenly, while NbC had a milder effect. The combined presence of TiN and NbC particles resulted in a more uniform grain refinement, enhancing the mechanical properties of the coatings. Notably, the (TiN + NbC)/HEAs composite coating demonstrated superior mechanical performance under the synergistic effect of both ceramic particles. The average microhardness value increased by 55.80 % compared to 17-4Ph stainless steel, and the wear rate was reduced by 88.38 %, with the wear mechanism primarily involving abrasive and oxidative wear.

Multi-layer formation by oxidation and solid-state crystallization of cold sprayed amorphous coatings during dry sliding wear

Amorphous alloy coatings, known for the exceptional wear resistance, have emerged as a key solution for enhancing the wear performance of magnesium alloys under harsh environments. In this study, Fe-based amorphous alloy coatings were deposited on magnesium alloy by cold spraying technology, and the influence of microstructural evolution on the wear performance of coatings under dry sliding wear conditions was discussed. The results showed that a dense adherent oxide layer with a thickness of ∼700 nm comprising nanograins of less than 8 nm was formed at the outmost surface, which played a role of self-lubricating. Underneath, a 1 μm thick nanocrystalline-amorphous layer with nanograins of ∼20 nm dispersed in the amorphous alloy matrix was formed through in-situ crystallization induced by flash temperature. This composite structure prevented the formation of shear bands in amorphous alloys and enhanced the durability. Therefore, the transition from abrasive wear to adhesive wear was a consequence of the microstructural evolution from a dual-phase composite layer to a self-lubricating oxide layer.