Low Wear Resistance Research Articles

Synergistic effect of V and Ag diffusion favored the temperature-adaptive tribological behavior of VAlN/Ag multi-layer coating

Surface coating technology offers several benefits (excellent wear resistance, low coefficient of friction-COF, better corrosion durability etc.) for key components used in harsh aero-engines. However, the development of temperature-adaptive lubricant coating is still the crucial issue. In this study, VAlN/Ag multi-layer coatings with various thickness ratios were fabricated by a hybrid deposition system composing of DCMS and HiPIMS techniques. Results showed that all coatings presented Ag layers with growth twins, and fcc-VAlN layers with columnar structure. Increasing the temperature from 25 to 650 ℃ led to a decrease of COF from 0.47 to 0.22 in coatings, where the lowest COF and wear rate was particularly achieved at 0.08 and 4.3 × 10−5 mm3N−1m−1 under higher rotation speed, respectively. Based on the microstructural characterizations on wear track of coating and wear scar of counter ball, the synergistic diffusion of V and Ag elements at elevating temperature stimulated the in-situ formation of distinctive Al2O3/AgVO3-Ag3VO4/Ag microstructure, which encompass lubricant phases for lower COF and high wear resistance. The reason behind of this phenomena could be attributed to the easily broken of Ag-O bonds in lamellar silver vanadium oxides at high temperature, accompanying the remarkable lubrication of Ag on top layer.

Temperature-adaptive lubrication of Ag doped Cr2AlC nanocomposite coatings

Self-lubricating nanocomposite carbides and nitrides coatings that enable to exhibit both low friction coefficient (CoF) and high wear resistance over a wide temperature range, are in high demand for mechanical components used in aerospace and marine systems. In this work, we developed high-purity Ag-doped Cr2AlC (Ag–Cr2AlC) nanocomposite coatings using a facile arc/sputter deposition technique followed by annealing. Compared to typical nanocrystalline Cr2AlC MAX phase coatings, the incorporation of Ag resulted in a unique nanocomposite structure, where Ag encapsulates elongated Cr2AlC nanograins. The dry sliding wear of this material was evaluated using the ball-on-disc method, with an Al2O3 ball as the counter body, at temperature ranging from 25 °C to 700 °C. Interestingly, Ag dopants contributed to a significant reduction in COF and wear rate at temperatures below 500 °C, while the synergistic effect of the Ag distributed at grain boundaries and the outermost oxides of Cr2O3 and Al2O3 generated during friction dominated the excellent self-lubrication at 500–700 °C. Notably, the Ag–Cr2AlC coatings promoted the in-situ formation of gradient bilayer oxides, consisting of a loosely coarse-grained inner layer and a densely refine-grained outmost layer. The combination of unique gradient oxides and a combined nanocomposite matrix allows the coating to accommodate plastic strains without extended cracks or localized brittle fracture.

A One-Step Novel Method to Fabricate Multigrade Ti6Al4V/TiN Composites Using Laser Powder Bed Fusion

Ti6Al4V is the most used alloy for implants because of its excellent biocompatibility; however, its low wear resistance limits its use in the biomedical industry. The additive manufacturing (AM) of Ti6Al4V is a well-established technique that is being used in many fields. However, the AM of Ti6Al4V composites is currently under investigation, and its manufacture using laser powder bed fusion (L-PBF) would result in a great benefit for many industries. The one-step novel concept proposed uses a gas-controlled L-PBF system that enables the AM of layers with different compositions. Six millimeter-edged cubes of Ti6Al4V were manufactured in an Ar atmosphere and coated with in situ Ti6Al4V/TiN layers by using an Ar–N2 mixture given the direct reaction between titanium and nitrogen. Unreinforced Ti6Al4V presented a martensitic microstructure, and TiN reinforcement dendrites and a minor Ti2N phase were gradually introduced into an α + β basketweave titanium matrix. The composites’ microhardness, nanohardness, and elastic modulus were 2, 3, and 1.5 times higher, respectively, than those of the Ti6Al4V. Porosity levels (caused by a lack of fusion, trapping gases, and interdendritic porosity), ranged from 7 to 12% (most measured 20–40 µm) and increased with the reinforcement content (15 to 25%). A scaled-up, proof-of-concept design of a hip implant stem was 3D printed using this nitriding method. Since the neck of the stem (top part) is more susceptible to the fracture and fretting corrosion process, the resulting graded material part consisted of unreinforced Ti6Al4V at the bottom and Ti6Al4V/TiN at the top. This change was controlled by gradually adding nitrogen to the atmosphere; moreover, it was found that the more nitrogen in the chamber, the more TiN reinforcement formed in the part. A microhardness of ~450 HV0.1 was measured at the bottom and gradually increased to ~900 HV0.1, with the increment corresponding to the in situ TiN reinforcement amount.

EFFECT OF CHILLS ON SAND CASTING OF ALUMINIUM ALLOY

This study investigated the effect of chill in the sand casting of aluminum alloy. Eight cylindrical rods of dimension 7.5mm × 40mm and a four-disc shape sample were cast using a sand mould. Alumina Oxide, Iron filling, and Zinc chills were stirred into the melt of three sand molds and the last sample was left unchilled. The investigation involved testing of mechanical properties and metallographic analysis of cast samples. The results revealed that the sample chilled with zinc has the highest mechanical properties but the lowest wear resistance (Tensile strength of 155.23312MPa, hardness of 50.24559BHN). Also, the sample chilled with alumina oxide revealed an evenly distributed microstructure due to its unique properties and its highest wear resistance. The iron filling chill sample displayed very close mechanical properties with the sample without chill (Tensile strength of 133.56225MPa, hardness of 43.18315BHN) (Tensile strength 133.85680Mpa, hardness of 42.94031BHN).

Study on the performance difference of porous asphalt mixture based on different modification processes

In order to discuss the difference of porous asphalt mixture (PAC) under different modification processes, the high viscosity HVA modified SBS modified asphalt, dry and wet process to mix PAC mixture, and test the technical indexes and performance of Marshall stability, flow value, high temperature stability, low temperature performance and wear resistance. The test results indicate that:Except that the stability of the dry porous asphalt mixture is basically the same as that of the wet modification, the other properties are worse than that of the wet porous asphalt mixture. The dosage of the dry porous asphalt mixture should be increased by about 2% to reach the level of wet modification. For the dry modification process, increasing the mixing time can reduce the gap between it and the wet process performance. It is recommended to increase the stirring time and add 1% of the original HVA dosage to achieve the performance level using wet modification.

Effects of Rare Earth Oxides on the Mechanical and Tribological Properties of Phenolic-Based Hybrid Nanocomposites.

The incorporation of rare earth oxides and nano-silica has been found to significantly enhance the mechanical and tribological characteristics of phenolic-based hybrid nanocomposites. In this work, the impact of these additives was investigated through single-factor experiments. The study revealed that cerium oxide and yttrium oxide were the primary factors influencing changes in the impact strength, shear strength, coefficient of friction, and wear rate. Additionally, the content of nano-silica exerted the most substantial influence on the hardness and compressive strength of the specimens. Furthermore, the material ratios of the phenolic-based hybrid nanocomposites were optimized using an orthogonal experimental design and a fuzzy comprehensive evaluation method. The optimal material ratio for these nanocomposites was determined to be 2% cerium oxide, 2.5% yttrium oxide, and 3% nano-silica, based on their mechanical, frictional, and wear properties. This research provides valuable insights for the development of new brake friction materials with low friction and high wear resistance and contributes to meeting the demand for polymer composites with superior mechanical performance in diverse applications.

Effect of C/N incorporation on structural and crystallographic properties of TaNbZr coatings deposited by double-glow plasma surface alloying on Ti-alloy substrate

The relatively low corrosion and wear resistance of Ti-alloy hinders full application of its meritorious low density-to-strength ratio. Here, we studied TaNbZr coatings by double-glow plasma surface alloying (DGPSA), with and without C- or N-incorporation, on TA15 substrate to enhance its tribological properties. The C-incorporation was introduced by adding a graphite target, which decreased the glow discharge on the Ta/Nb/Zr targets and thus reduced the deposition rate by ∼55 %. In comparison, the N-incorporation was introduced by feeding N2, partly replacing the Ar working gas flow, which reduced the sputtering yield of the metal targets that in turn reduced the deposition rate by ∼60 %. Hole and hill-in-hole structures have been observed on TaNbZrC with the size and density much higher than those on TaNbZr and TaNbZrN, which was attributed to undesired graphite particles ejected from the target and deposited directly onto the growing surface of the substrate. The localized ejection induced by the graphite particles upon the substrate-associated glow plasma gave rise to the hole and hill-in-hole structures. The C- and N-incorporation modified the surface alloying reactions, leading to different microstructure and smoothness on the surface, compositional changes of the ‘buffer’ layer at the coating/substrate interface, and varied crystallographic texturing of the coatings. Nanoindentation measurements at the cross-section across the coating/substrate interface provide evidence for the enhanced hardness, not only at the coatings but also at the near-interface regions of the substrate. These observations, together with bonding strength and tribology tests at elevated temperatures, shed new light on developing protective coatings on Ti-alloy by DGPSA.

Microstructure and Wear Behavior of Ti-xFe-SiC In Situ Composite Ceramic Coatings on TC4 Substrate from Laser Cladding.

Titanium alloys are widely used in various structural materials due to their lightweight properties. However, the low wear resistance causes significant economic losses every year. Therefore, it is necessary to implement wear-resistant protection on the surface of titanium alloys. In this study, four types of in situ composite ceramic coatings with two-layer gradient structures were prepared on a Ti-6Al-4V (TC4) substrate using laser cladding. In order to reduce the dilution rate, a transition layer (Ti-40SiC (vol.%)) was first prepared on TC4 alloy. Then, a high-volume-fraction in situ composite ceramic working layer (Ti-xFe-80SiC (vol.%)) with different contents of Fe-based alloy powder (x = 0, 5, 10 and 15 vol.%) was prepared. The working surface of Ti-40SiC (TL) exhibited a typical XRD pattern of Ti, TiC, Ti5Si3, and Ti3SiC2. In comparison, both Ti-80SiC (WL-F0) and Ti-5Fe-80SiC (WL-F5) exhibited similar phase compositions to the TL coating, with no new phase identified in the coatings. However, the TiFeSi2 and SiC phases were presented in Ti-10Fe-80SiC (WL-F10) and Ti-15Fe-80SiC (WL-F15). It is proven that the addition of the Fe element could regulate the in situ reaction in the original Ti-Si-C ternary system to form the new phases with high hardness and good wear resistance. The hardness of the WL-F15 (1842.9 HV1) is five times higher than that of the matrix (350 HV1). Due to the existence of self-lubricating phases such as Ti5Si3 and Ti3SiC2, a lubricating film was presented in the WL-F0 and WL-F5 coatings, which could block the further damage of the friction pair and enhance the wear resistance. Furthermore, a wear-transition phenomenon was observed in the WL-F10 and WL-F15 coatings, which was similar to the friction behavior of structural ceramics. Under the load of 10 N and 20 N, the wear volume of WL-F15 coating is 5.2% and 63.7% of that in the substrate, and the depth of friction of WL-15 coating is only 14.4% and 80% of that in the substrate. The transition of wear volume and depth can be attributed to the wear mechanism changing from oxidation wear to adhesive wear.

CATHODIC PLASMA ELECTROLYTIC DEPOSITION (CPED) TECHNIQUE FOR SURFACE STRENGTHENING OF TITANIUM AND TITANIUM ALLOYS: A MINI REVIEW

Due to the unique properties of titanium (Ti) and its alloys, it has a particularly wide range of applications in aerospace, automotive, medical and other fields. However, the problems of low surface hardness, high friction coefficient and low wear resistance of Ti alloys limit its development to a certain extent. The destruction of Ti and its alloys often occurs on the surface of materials such as wear damage, corrosion, and oxidation resistance. Therefore, the exploration and application of surface strengthening technology is particularly important. The cathodic plasma electrolytic deposition (CPED) technology, as a surface modification technology, can achieve better adhesion and facilitate the material to achieve better comprehensive performance. This paper briefly introduces the basic concepts, principles and development progress of CPED. Starting from the preparation of ceramic coatings, metal coatings, diamond-like carbon films and composite coatings, it summarizes the application of CPED in Ti and its alloys. Applications in alloys to improve thermal oxidation resistance, wear resistance, corrosion resistance, and film-based adhesion. At the end, its development in the new era environment is prospected.

To the question of improving the wear resistance of high manganese steel castings

Nowadays, one of the most significant tasks in production of equipment for mining industry is import substitution. In this regard, investigations aimed at improving the technologies of manufacturing high quality castings from wear resistance manganese austenitic steels seems to be relevant. The results of metallographic research of high manganese steel samples from foundries producing crushing plates and crushing cones, track links, hammers, shovel teeth, tooth caps etc. are given. Analysis of the microstructure of the presented castings showed that they are characterized by a coarse-grained structure with an austenite grain size of 1–2 points. In most cases, a thickened grain boundary, presence of manganese carbides along the grain boundaries and non-metallic inclusions are observed. The revealed mi-crostructure features of castings are one of the main indicators of low wear resistance of high manganese steel parts. The operational and technological factors affecting the wear resistance of castings are listed. Recommendations for improving the quality of steel products made from manganese steels are proposed, and the results of using original complex modifiers developed at NPP Technology Company in real manufacturing conditions are presented.

Experimental investigation on triglycidyl isocyanurate‐based tribologically functional composites

AbstractThe aim of this study is to prepare epoxy/polytetrafluoroethylene (PTFE)/glass fiber (GF) composites (EPGs) with the unique characteristics of low friction and high wear resistance based on triglycidyl isocyanurate (TGIC). The tribological properties of composites with different filler ratios under different working conditions were systematically studied. At the maximum filler content of 40 wt% PTFE, the minimum coefficient of friction (COF) and wear rate reached 0.079 and 0.45 × 10−6 mm3/N·m. The hardness decreased by 44.2% and the density increased by 18.3%. The worn surfaces and transfer films were observed and analyzed by scanning electron microscopy (SEM) and x‐ray photoelectron spectroscopy (XPS). The increasing tendency of velocity and amplitude is beneficial to reduce the carbon‐rich region and further enhance the formation of transfer films. It is proved that the tribological properties of TGIC‐based epoxy composites are higher than those of other types of epoxy composites. This study offers great insight into the tribological applications of TGIC‐based epoxy composites.Highlights Epoxy/PTFE/GF composites (EPGs) were prepared using TGIC as the base material. EPGs have good mechanical and tribological properties. The COF of EPG3 reaches 0.079 and the wear rate becomes 0.45 × 10−6 mm3/(N·m). The increasing tendency of velocity and amplitude is beneficial to reduce the carbon‐rich region and further enhance the formation of transfer films.

Corrosion and friction behaviours of MoSi2/MoS2 nanoparticles incorporated tinted coating on Ti6Al4V alloy

A blue tinted coating was fabricated on TC4 alloy employing anodizing treatment with the aim of improving corrosion and wear resistance. Various concentrations of MoS2 or MoSi2 nanoparticles were incorporated into the coatings. The addition of the particles affected the surface roughness, hardness and thickness of the coatings, thus had a comprehensive influence on the wear and corrosion property. The introduction of MoSi2 particles remarkably improved the hardness of the coatings, and improved the wear resistance consequently. The nonconductive MoS2 impeded the penetration of corrosive medium, while conductive MoSi2 introduced additional galvanic couples at the interface which deteriorated the corrosion resistance. Excess concentration of the added particles impeded the growth of oxide layer, resulting in lower corrosion and wear resistance of the coatings.

Effect of Cu addition on the tribological properties and oxidation behavior of nanomultilayered AlTiN/Cu coatings

As a soft metal, the addition of Cu has an important influence on the high-temperature tribological properties and oxidation behavior of nanomultilayered AlTiN/Cu coatings. At room temperature (RT), due to abrasive wear, the AlTiN coating exhibited a high friction coefficient of 0.97 and low wear resistance. After adding Cu layer, the friction coefficient gradually decreased to 0.59 at 18.4 at.% Cu due to the lubricating effect of soft metal Cu and CuO, and the best wear resistance was achieved at 2.9 at.% Cu. At 800 °C, the oxidation resistance sharply reduced after adding Cu layer, and exhibited oxidation delamination. At low Cu contents (≤4.5 at.%), by the inward diffusion of O, a mixed oxide layer of Al2O3, TiO2, and CuO formed. At 18.4 at.% Cu, by the outward diffusion and oxidation of Cu, double-layer oxides formed, and the top layer of CuO contributed to a low friction coefficient of 0.53, but also caused a reduce in the wear resistance.

To elucidate the effect of alloying elements for enhanced nitriding of aluminum: A multiscale computational study

The limitations of aluminum (Al) are discussed in certain industrial applications, owing to its low hardness and wear resistance. To overcome these limitations, surface modification techniques, such as the formation of aluminum nitride (AlN) layers on the Al surface, have been explored. However, conventional surface-nitriding processes have low productivity, and it is essential to develop a cost-effective method to ensure higher nitriding rates. This paper presents the results of a multiscale computational study on the atomic-scale mechanisms involved in gas nitriding processes and the effects of alloying elements on reaction kinetics using density functional theory calculations. This study also provides insights into the thermodynamic stability and kinetics of the process, contributing to the design and optimization of the nitriding process for the formation of AlN on Al surfaces using Thermo-Calc. and microkinetic analyses. This study demonstrates the potential of multiscale computational methods for advancing the understanding of surface modification techniques and their applications for nitriding on the surface of Al and suggests the best alloying element to enhance the nitriding rate.

Effect of thermal oxidation on the dry sliding friction and wear behaviour of CP-Ti on CP-Ti tribopairs

Thermal oxidation (TO) has proven to be a cost-effective and efficient technique to engineer the surfaces of titanium and its alloys to achieve enhanced surface properties. The benefits of TO treatment in enhancing the tribological properties of titanium have been demonstrated by many investigators. However, most of the reported tribological studies have been based on the contact between a TO treated titanium specimen and a counter-body made of other materials, mainly ceramics, steels and polymers. Very few studies have been reported on the friction and wear behaviour of TO treated titanium sliding against TO treated titanium. In this work, the effect of thermal oxidation on the dry sliding friction and wear behaviour of commercially pure Ti (CP-Ti) on CP-Ti tribopairs was investigated under loading conditions ranging from elastic contact to plastic contact. Comparisons were made among three contact pairs: (1) untreated Ti on untreated Ti (Ti–Ti), (2) untreated Ti on TO treated Ti (Ti-TO) and (3) TO treated Ti on TO treated Ti (TO-TO). The results show that the TO-TO contact pair presents an ideal material combination to achieve the best tribological performance in terms of low friction and superior wear resistance. On the other hand, the Ti–Ti pair presents the worst combination in terms of tribological performance. While the Ti-TO pair performs better than the Ti–Ti pair tribologically, it is not as good as the TO-TO pair. It is essential to thermally oxidize both specimens in order to achieve optimal tribological performance. It is the oxide layer-on-oxide layer contact that imparts the excellent tribological performance. Failure of the oxide layer in one of the contact bodies can lead to high and unstable friction and increased wear from both contacting bodies. The tribological performance of the three contact pairs and the failure mechanism of the oxide layer are discussed in the paper. The results of this work suggest that the TO treated Ti on TO treated Ti contact pair would have potential tribological applications in engineering.

Study of the influence of alphoning on the structure and properties of the alloy BT6

The paper considers the influence of two technologies of alfing (oxidation) on the structure and properties of the deformable titanium alloy BT6, which is used, in particular, in the aviation and space industries. The application of oxide coating by methods of chemical-thermal treatment (CTO) allows to compensate for the main drawback of the alloy – low wear resistance of the surface. The initial set of properties increases. The objects of research are titanium alloy BT6 and its oxide coatings. Two samples of the part with oxide coatings obtained by different technologies were compared. The first technology is alfing in fine-grained graphite, the second is alfafing in a vacuum. The aim of the work is to find out the influence of two technologies of alfing on the structure and properties of the BT6 alloy. Alfalfing was carried out: 1) in fine-grained graphite at a temperature of 800 ± 10 ° C with exposure for 8 hours; 2) in an electric furnace at a temperature of 760–780 ° C in a vacuum of 10-1 – 10-3 mm Hg. art. for 1.5–2 hours. A study of the microstructure (light and electron microscopy) was performed. We used a microscope type Carl Zeiss Axio Observer A1m using a digital camera, adapter devices for converting an optical signal, a computer. Statistical processing was carried out according to the SIAMS700 program. Electron microscopic studies were performed using a scanning electron microscope (SEM) EVO 50 with an energy-dispersive microanalyzer INCA Energ 350. X-ray phase analysis was carried out using an X-ray diffractometer Shimadzu XRD7000, Japan (CuKa radiation, monochromator), in the following mode: range from 5 to 70 ° on a scale of 2θ, increments of 0.03°, scanning speed of 1.5 ° / min. Powders obtained from two types of coatings were investigated. The microhardness of the samples was measured on the DM8 microhardometer according to GOST 9450–76. The wear resistance of the alloy was assessed at a special laboratory installation. The phase composition and structure of the BT6 alloy after alphoning were clarified. In the diffusion layer, the following were detected: after alphonation in graphite – TiO2 phases; Ti3O; TiN. After carbonation in vacuum – TiO2; Ti6O11. In the alphad layer, after processing in graphite, grains of α – solid solution, intermetallics Ti–Al-V, Ti–V and Ti–Al were detected; the alphied layer contains more titanium after treatment in vacuum, and areas with 100% (at.) titanium have also been identified; the region of solid solution (α) and the intermetallics Ti–Al-V, Ti–V and Ti–Al are visible. The thickness of the oxidized layer is on average 103.6 μm (graphite), and in a vacuum - 66.8 μm. The average grain size in the layer is 17.2 μm (graphite); 6.0 μm (vacuum). It has been established that chemical-thermal treatment (alfing) contributes to a significant increase in microhardness in the diffusion layer. The hardness of HV580 (vacuum) and HV724 (graphite) was obtained on the surface. Alfalfing in graphite and in vacuum ensures the wear resistance of the product, but the best result is obtained after alfafing in a vacuum. Both technologies improve the properties, but it is more profitable to carry out alfing in a vacuum, since in this case the process is carried out within 2 hours instead of 8 hours in graphite. Alfing (oxidation) provides wear resistance of the BT6 alloy, which contributes to the reliable operation of the product during operation.

Structure, mechanical and tribological properties of Ta-xN coatings deposited by reactive HiTUS

This work investigates the structure, mechanical, and tribological properties of Ta-xN coatings deposited using reactive High Target Utilization Sputtering (HiTUS) with a focus on the role of tribological layers formed in the sliding contacts. The scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Raman spectroscopy observations revealed that the gradual increase of nitrogen flow results in the transition from textured fcc Ta structure (without nitrogen) toward mixed sub-stoichiometric Ta-Ny/Ta2N/amorphous structures up to near-stoichiometric fcc TaN coatings. The highest hardness HIT ∼37 GPa and indentation modulus EIT ∼375 GPa as well as the lowest coefficients of friction (COF) in the range 0.16–0.36 and wear rates around 3 × 10−7 mm2/N·m were obtained in the layer with Ta2N structure. The unique combination of low COF and high wear resistance combined with high hardness and stiffness were attributed to the shear sliding between Ta2O5-based transfer film in the wear track and pure alumina ball.

Lubrication, wear resistance and corrosion protection on aluminum alloy toward multifunctional coatings with nano-CeO2 inhibition effect

The coupling effect of wear and corrosion aggravates the damage and failure of key moving parts of high-end equipment, leading to a significant reduction in their service life. In present work, a functional integrated composite coating with exceptional corrosion resistance and tribological properties was developed by utilizing the responsive corrosion inhibition of nano‑cerium oxide (nano-CeO2) and the low surface energy and low shear characteristics of polytetrafluoroethylene (PTFE). The tribological behaviors and corrosion protection performance of coatings on aluminum alloy 2024 were evaluated and the corrosion inhibition mechanism was further discussed. The results revealed that Ce3+ on the surface of nano-CeO2 reacts with OH− generated by the REDOX reaction of the cathode to produce a uniform and stable passivation film, which can effectively improve the corrosion resistance of the metal matrix. Notably, the most obvious passivation effect is presented when the 2 % addition of nano-CeO2 as the larger low-frequency impedance modulus of 4.49 × 1010 Ω·cm2 and higher phase angle of 88°. The introduction of PTFE not only changes the coating from hydrophilic to hydrophobic, but also further improves the shielding properties of the coating. The low-frequency impedance modulus of the coating further increases by an order of magnitude to 2.38 × 1011 Ω·cm2, and its neutral salt spray resistance exceeds 210 days. Besides, the friction coefficient is reduced by 77.43 % and the wear resistance improved by 6.8 times compared with phenolic epoxy coating. Due to the enhancement and corrosion inhibition effect of nano-CeO2, the lower friction coefficient (0.044) and good wear resistance are further presented under the corrosive medium condition of 3.5 % NaCl solution.

A Review of the Laser Cladding of Metal-Based Alloys, Ceramic-Reinforced Composites, Amorphous Alloys, and High-Entropy Alloys on Aluminum Alloys

As one of the lightest structural metals, the application breadth of aluminum alloys is, to some extent, constrained by their relatively low wear resistance and hardness. However, laser cladding technology, with its low dilution rate, compact structure, excellent coating-to-substrate bonding, and environmental advantages, can significantly enhance the surface hardness and wear resistance of aluminum alloys, thus proving to be an effective surface modification strategy. This review focuses on the topic of surface laser cladding materials for aluminum alloys, detailing the application background, process, microstructure, hardness, wear resistance, and corrosion resistance of six types of coatings, namely Al-based, Ni-based, Fe-based, ceramic-based, amorphous glass, and high-entropy alloys. Each coating type’s characteristics are summarized, providing theoretical references for designing and selecting laser cladding coatings for aluminum alloy surfaces. Furthermore, a prediction and outlook for the future development of laser cladding on the surface of aluminum alloys is also presented.

Tribological properties of laser-cladded Fe-based amorphous composite coatings under dry and lubricated sliding

Fe-based amorphous composite coatings are promising surface coating materials, because of their low cost, high hardness, and superior wear resistance. In the present study, Fe-based composite coatings with various amorphous contents (35.9–59.3%) were deposited onto 1045 steel via laser cladding, and the influence of laser-cladding parameters on the amorphous content was analysed. The cross sections of the coating layer and ground coating surface were then characterised in terms of the microstructure, phase composition, amorphous content, grain size, and microhardness. Importantly, the tribological properties of coatings with various amorphous contents under both dry and lubricated sliding conditions with light and heavy loads were systematically investigated. The microstructure of the crystalline/amorphous mixture was found to be a function of the temperature gradient, cooling rate, and chemical composition. The high microhardness was related to the amorphous content and grain size. The tribological properties were found to be insensitive to the amorphous content under both dry and lubricated conditions under light and heavy loads. The manifold morphologies of the wear tracks and the transition of the wear mechanism were the result of the combined effects of the amorphous content, phase composition, and size and distribution of the crystalline phase.