Surface Coatings Research Articles

Internal Doping and Surface Coating: Mn/La-HCF @ Fe-HCF Composites as High-Performance Cathode Materials for Sodium-Ion Batteries

Manganese-based Prussian blue analogue (Mn-HCF) has outstanding advantages such as a high discharge platform, high discharge capacity and high energy density compared with other PB and PBAs, which is a very valuable cathode material for sodium-ion batteries. However, the rapid decrease in capacity in the cycle process by the Jahn–Teller effect caused by [Formula: see text] is the main obstacle to the commercialization of Mn-HCF. In this work, Mn/La-HCF @ Fe-HCF was synthesized by doping La element into the Mn-HCF phase to suppress the Jahn–Teller effect of Mn ions and coating the Fe-HCF phase outside to protect the Mn-HCF phase from electrolyte corrosion. Benefiting from the inhibition of the Jahn–Teller effect of [Formula: see text] by the abundant electronic energy level structure of La element and the protection of Fe-HCF phase relative to Mn-HCF phase, the initial discharge capacity of Mn/La-HCF @ Fe-HCF can reach 135.6 mAh [Formula: see text] at current density of 0.1 C, and it still has a high discharge capacity of 112.2[Formula: see text]mAh [Formula: see text] at current density of 5 C. After 300 cycles at a current density of 2 C, the reversible capacity of 117.6[Formula: see text]mAh [Formula: see text] is maintained (capacity retention rate is 86.1%). The results show that this method of internal doping and outsourcing can greatly improve the electrochemical performance of Mn-HCF, and provide feasible ideas for the commercialization of Mn-HCF.

Optimizing catalytic surface coatings in FDM-Printed sustainable materials: Innovations in chemical engineering

This research brings in the advancement of sustainable, high-performance engineering solutions where catalytic surface coatings are pursued to integrate with fused deposition modeling printed sustainable materials. The work is centered on optimization of catalytic coatings for higher efficiency and durability, which is innovatively linked with the advance chemical engineering. In probing the influence of different catalytic materials and deposition methods on FDM-printed substrates, we applied advanced surface functionalization, nano-engineering, and computational modeling techniques. Among other elements, this research approach utilized ANN with PSO algorithms in optimizing the parametric setting that best yielded high catalytic performance. The results obtained show considerable improvements in catalytic activity and the coating's lifetime, promising such applications in energy, environmental, and chemical industries. This study not only draws attention to the potential of FDM-printed sustainable materials but also demonstrates the potential of chemical engineering innovations for optimizing catalytic surface coatings toward the development of high-performance, sustainable technologies.

Preparation of Nano- and Microparticles Obtained from Polymerization Reaction and Their Application to Surface Coating of Woody Materials

A surface coating of polymer particles of different hydrophobicity and wide-ranged size is helpful for the surface modification of materials such as woody thin board (WTB) derived from biomass. A preparation method for polymer particles was, in this study, proposed using a capillary-type flow system. Under hydrothermal conditions, the refinement of dispersed oil droplets in water (O/W emulsions) and the polymerization reaction could be simultaneously advanced, and polymer particles of polystyrene (PS), polyvinyl alcohol (PVA), polymethyl methacrylate (PMMA), and poly-L-lactic acid (PLLA) with a particle size of about 100 nm could be synthesized. The coating of polymer particles gave an improved effect on the water repellency of WTBs due to the hydrophobicity of polymer particles and an alteration of surface roughness, and it also provided long-term stability (more than 6 years).

Influence of Molybdenum Addition on the Structure, Mechanical Properties, and Cutting Performance of AlTiN Coatings

Though AlTiN coating has been intensively studied, there is still a need to develop AlTiN coating to meet the growing demand of industrial machining. One effective way to improve the performance of AlTiN coating is by adding alloying elements. In this study, AlTiN and AlTiMo coatings were deposited using multi-arc ion plating to investigate the influence of molybdenum addition on the structure, mechanical properties, and cutting performance of AlTiN coatings. Spherical droplets formed on the surfaces of both coatings, with the AlTiMoN coating exhibiting more surface defects than the AlTiN coating. The grazing incidence X-ray diffraction results revealed the formation of an (Al,Ti)N phase formed in the AlTiN and AlTiMoN coatings. Molybdenum doping in the AlTiMoN coating slightly reduced the grain size. Both coatings exhibited excellent adhesion to the substrate. The hardness (H), elastic moduli (E), H/E, and H3/E2 ratios of the AlTiMoN coating were higher than those of the AlTiN coating. The improvement in the mechanical properties was attributed to grain refinement and solution strengthening. Molybdenum doping improved the tribological properties and cutting performance of the AlTiN coatings, which was ascribed to the formation of MoO3 as a solid lubricant. These results show a path to increase the performance of AlTiN coating through molybdenum addition and provide ideas for the application of AlTiMoN coatings for cutting tools.

Public surface disinfection every 2 hours can reduce the infection risk of norovirus in airports up to 83.

Norovirus, primarily transmitted via fomite route, poses a significant threat to global public health and the economy. Airports, as critical transportation hubs connecting people from around the world, has high potential risk of norovirus transmission due to large number of public surfaces. A total of 21.3 hours of video episodes were recorded across nine functional areas at the airport, capturing 25,925 touches. A surface transmission model based on a Markov chain was developed. Using the beta-Poisson dose-response model, the infection risk of norovirus and the effectiveness of various interventions in different airports' areas were quantified. Without any preventive measures, restaurants at airports exhibited the highest risk of norovirus transmission, with an infection probability of 8.8×10-3% (95% CI, 1.5×10-3% -2.1×10-2%). This means approximately 4.6 (95% CI, 0.8-10.9) out of 51,494 passengers who entered the restaurants would be infected by an infected passenger. Comparing with no surface disinfection, disinfecting public surfaces every 2 hours can reduce the risk of norovirus infection per visit to the airport by 83.2%. In contrast, comparing with no hand washing, handwashing every 2 hours can reduce the infection risk per visit to the airport by only 2.0%, making public surface disinfection significantly more effective than handwashing. If the mask-wearing rate increases from 0% to 50%, the infection risk of norovirus would be decreased by 48.0% (95% CI, 43.5-52.3%). Furthermore, using antimicrobial copper/copper-nickel alloy coatings for most public surfaces could reduce the infection risk by 15.9%-99.2%.

CMAS corrosion behavior of interface for EB-PVD Gd2Zr2O7/YSZ thermal barrier coatings

Thermal barrier coatings (TBCs) of aero-engine surfaces are facing complex working conditions such as high-temperature oxidation, hot-cold cycling, and CMAS corrosion. Gd2Zr2O7 (GZO)/YSZ bilayer ceramic TBCs are one of the coating systems that have been applied in aero-engine TBCs. One of the failure problems faced by the columnar crystalline bilayer GZO/YSZ TBCs prepared by electron beam-physical vapor deposition (EB-PVD) technology in high-temperature environments is the CMAS high-temperature corrosion problem. In this study, CMAS corrosion tests of GZO/YSZ bilayer structure TBCs were conducted at 1200 °C for 1h, 2h and 4h, respectively. The focus was on exploring the corrosion characteristics and mechanisms of the coating interface and surface after high-temperature corrosion. It was found that CMAS corrosion was dominated at the coating interface, accompanied by coating sintering, resulting in coating spalling at the interface. The coating interface was also analyzed by TEM after 4h corrosion, and it was found that an apatite phase was formed at the GZO/YSZ interface, which was embedded in the lattice of YSZ. Finally, the corrosion failure mechanism of the GZO/YSZ bilayer structure TBCs was proposed by the above CMAS high-temperature corrosion test.

Preparation of Waterborne Polyurethane Coatings with Enhanced Mechanical Properties and Superhydrophobic Surface

Waterborne polyurethane (WPU) coatings are recognized for their environmental friendliness and non-toxic nature. However, the presence of abundant hydrophilic groups within their polymer networks often restricts their hydrophobicity and mechanical performance. In this study, we utilized two distinct diols to design the molecular structure of WPU, aiming to enhance its mechanical properties by optimizing microphase separation and crystallinity, achieving a tensile strength of 24.13 MPa and a strain of 1350%. The resultant WPU exhibited high cohesion and abundant hydrogen bonding sites, which contributed to its strong adhesion of 8.31 MPa. Moreover, inspired by the self-cleaning function of lotus leaf-micro-nipples, we made the surface superhydrophobic by micro-nano structure. The irregularly embedded structure was formed between the WPU and SiO2@hbp. The surfaces of WPU coatings formed the peak-valley structure similar to the lotus leaf, achieving a water contact angle of 162° and a sliding angle near 1°. Additionally, the self-cleaning property of the coatings was preserved after 200 cycles of friction, each with a single friction distance of 40cm. The environmental friendliness and excellent self-cleaning capabilities of the coating highlight its potential for practical applications and provide a valuable reference for developing waterproof self-cleaning coatings.

A novel sustainable wood-based negative air anion generator utilizing in-situ polymerization of polylactic acid to reinforce the cellulose framework

The generation of negative air ions (NAI) by furniture contributes to indoor air purification and enhances the living environment. However, commercially available furniture typically relies on surface coatings to release NAI. Over time, the degradation of these coatings leads to a significant decline in NAI release performance, presenting a persistent challenge for sustained effectiveness. Here, a novel sustainable wood-based negative air anion generator (SWNG) had been developed, utilizing a cellulose framework as the substrate. The in-situ synthesis of polylactic acid (PLA) within the wood incorporated titanium dioxide (TiO2), tourmaline (TL), and cellulose acetate, firmly anchoring these materials within the wood structure. Compared to the cellulose framework alone, the NAI production of the SWNG had increased by 406.67 %. The impregnation with PLA enhanced the enduring photocatalytic activity of TiO2 and TL in this innovative wooden NAI generator. After undergoing 200 cycles of testing between −40 °C and 50 °C, it continued to sustain NAI production, demonstrating exceptional antibacterial performance. Overall, this study introduced a novel sustainable wood-based negative air ion generator as a highly stable material with sustainable properties, offering significant potential for applications in improving indoor air quality and in the domain of home construction.

Evaluating the Integrity of Surface Coatings on a Pipe-shaped Aluminum Alloy through Environmental Testing

Evaluating the Integrity of Surface Coatings on a Pipe-shaped Aluminum Alloy through Environmental Testing

Enhanced Cycling Performance of the LiNiO2 Cathode in Li-Ion Batteries Enabled by Nb-Based Surface Coating.

Lithium nickel oxide (LNO) is a promising cathode candidate in various next-generation battery technologies. To increase its stability, doping and surface coating have become key strategies. Among various elements, niobium stands out for its dual role as an effective dopant and the advantages of its oxide phases as coatings. In this study, we explore Nb-based coating of LNO, utilizing methods that minimize or eliminate solvent use. Additionally, the coated samples were treated at two different temperatures to study their effect on properties and electrochemical performance. Our results demonstrate that the coating process strongly affects the cell cyclability and further highlight the potential of Nb-based protective coatings in enhancing LNO as a cathode active material for application in high-energy-density Li-ion batteries.

Salt-Responsive Switchable Block Copolymer Brushes with Antibacterial and Antifouling Properties.

A strategy for multifunctional biosurfaces exploiting multiblock copolymers and the antipolyelectrolyte effect is reported. Combining a polyzwitterionic/antifouling and a polycationic/antibacterial block with a central anchoring block for attachment to titanium oxide surfaces affords surface coatings that exhibit antifouling properties against proteins and allow for surface regeneration by clearing adhering proteins by employing a salt washing step. The surfaces also kill bacteria by contact killing, which is aided by a nonfouling block. The synthesis of block copolymers of 4-vinyl pyridine (VP), dimethyl 4-vinylbenzyl phosphonate (DMVBP), and 4-vinylbenzyltrimethyl ammonium chloride (TMA) is achieved on the multigram scale via RAFT polymerization with good end group retention and narrow dispersities. By polymer analogous reactions, poly(4-vinyl pyridinium propane sulfonate-block-4-vinylbenzyl phosphonic acid-block-4-vinylbenzyl trimethylammonium chloride) (P(VSP64-b-PA14-b-TMA64)) is obtained. The antifouling properties against the model protein pepsin and the salt-induced surface regeneration are shown in surface plasmon resonance (SPR) experiments, while independently the antibacterial and antifouling properties of coated titanium substrates are successfully tested in preliminary microbiological assays against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). This strategy may contribute to the development of long-term effective antibacterial implant surface coatings to suppress biomedical device-associated infections.

Hybrid poly(lactide-co-glycolide) membranes incorporated with Doxycycline-loaded copper-based metal–organic nanosheets as antibacterial platforms

The rise of antimicrobial resistance necessitates innovative strategies to combat persistent infections. Metal-organic frameworks (MOFs) have attracted significant attention as antibiotic carriers due to their high drug loading capacity and structural adaptability. In particular, 2D MOF nanosheets are emerging as a notable alternative to their traditional 3D relatives due to their remarkable advantages in enhanced surface area, flexibility and exposed active region properties. Herein, we synthesized 2D copper 1,4-benzendicarboxylate (CuBDC) nanosheets and utilized them as a carrier and controlled release system for Doxycycline (Doxy@CuBDC), for the first time. The Doxy@CuBDC nanosheets were subsequently incorporated into Poly(lactic-co-glycolic acid) (PLGA) electrospun membranes (Doxy@CuBDC/PLGA). The resultant bioactive fibrous membranes exhibited double-barrier controlled release properties, extending the Doxy release up to ∼9 d at pH 7.4 and 5.5. Significant inhibitory effects againstStaphylococcus aureusandEscherichia coliwere observed. The morphological analyses revealed the deformed bacterial cell structures on Doxy@CuBDC/PLGA membranes that indicates potent bactericidal activity. Furthermore, cytotoxicity assays demonstrated the non-toxic nature of the fabricated membranes, underscoring their potential use for biomedical applications. Overall, the hybrid antibacterial PLGA membranes present a promising strategy for combating microbial infections while maintaining biocompatibility and offer a versatile approach for biomedical material design and surface coatings (e.g. wound dressings, implants).

3D printing of biomimetic hierarchical surface textures using L-PBF for improving tribological performance of Ti6Al4V alloy

Energy and material losses due to friction and wear during the use of materials bring about very serious costs in every sector. In order to minimize friction and wear losses of materials, different surface engineering applications are used, especially surface coatings, thermal, mechanical and thermochemical processes. On the other hand, it has been shown in recent years that the tribological properties of materials can be controlled by creating different types of biomimetic hierarchical patterns on the surface of materials. Therefore, this study investigates both the individual and the synergetic effects of both biomimetic surface textures and thermal oxidation process on the tribological performance of Ti6Al4 V alloy. For this purpose, hierarchical models were produced using the laser powder bed fusion (L-PBF) technique, which is one of the additive manufacturing methods. Snake skin, shark skin and tree frog models were used as biomimetic hierarchical models. Additionally, flat and random snake skin models were used to examine the effect of texture orientation. Moreover, thermal oxidation was carried out at 700 ⁰C for 2 h and 4 h and the wear tests were carried out using a reciprocation-type tribo-tester under dry and simulated body fluid (SBF) conditions. As the oxidation time increased, the hardness and surface roughness of the material increased. A significant improvement in the wear rate of biomimetic models was observed compared to the non-textured sample. Lower tribological performance was observed in the tree frog model (hexagonal geometry) compared to other biomimetic models due to the presence of sharp corners. In particular, the snakeskin model provided the best wear rate because it trapped wear residue and provided additional hydrodynamic pressure. The highest tribological performances for all samples were observed in the samples oxidized at 700 ⁰C for 4h.

Thioether-Functionalized Cellulose for the Fabrication of Oxidation-Responsive Biomaterial Coatings and Films.

Biomaterial coatings and films can prevent premature failure and enhance the performance of chronically implanted medical devices. However, current hydrophilic polymer coatings and films have significant drawbacks, including swelling and delamination. To address these issues, hydroxyethyl cellulose is modified with thioether groups to generate an oxidation-responsive polymer, HECMTP. HECMTP readily dissolves in green solvents and can be fabricated as coatings or films with tunable thicknesses. HECMTP coatings effectively scavenge hydrogen peroxide, resulting in the conversion of thioether groups to sulfoxide groups on the polymer chain. Oxidation-driven, hydrophobic-to-hydrophilic transitions that are isolated to the surface of HECMTP coatings under physiologically relevant conditions increase wettability, decrease stiffness, and reduce protein adsorption to generate a non-fouling interface with minimal coating delamination or swelling. HECMTP can be used in diverse optical applications and permits oxidation-responsive, controlled drug release. HECMTP films are non-resorbable in vivo and evoke minimal foreign body responses. These results highlight the versatility of HECMTP and support its incorporation into chronically implanted medical devices.

Morphology and Properties of the Laser-Irradiated Composition “Chrome Coating — Copper Substrate”

Introduction. During pulsed laser processing and modification of the surface of non-ferrous alloys and coatings based on them, several still unresolved issues arise. In particular, the extreme thermal deformation conditions of laser processing are not linked to the peculiarities of structure formation and formation of properties in irradiated “coating — copper substrate” compositions. A metal physical analysis of the possibility and reasons for increasing the adhesion strength of coatings to a metal (copper) substrate during high-speed laser processing is insufficiently substantiated and evidence-based. To make a reasonable choice of technological parameters for the surface hardening mode of non-ferrous alloy products, as well as for obtaining high-quality workable composite layers on their surface, it is necessary to solve the above issues and tasks. The aim of this article is to determine the possibility and conditions for increasing the adhesion strength of a chrome coating to a copper substrate under laser irradiation of the composition.Materials and Methods. Metal physical studies in the work were carried out on samples of non-ferrous alloys of the Cu–Zn system with a chrome electrochemical coating with a thickness of 20 μm. The “copper substrate — chrome coating” composition was irradiated at a Kvant-16 installation with a radiation power density of 70–250 MW/m2. Metallographic structural analysis, scanning probe microscopy, and durometric studies were used in the work.Results. It has been calculated that the dynamic and thermal stresses arising in the laser-irradiated compositions “chrome coating — copper substrate” were about 320 MPa. Metal physical studies revealed that, in extreme thermal deformation conditions of laser treatment, the effect of contact melting was manifested at the boundary of the coating with the copper base. Dynamic recrystallization occurred in the surface layers of the irradiated L62 copper alloy, resulting in the formation of grains with a size of 4.5–5.0 μm on the surface of the alloy with an initial grain size of 25 μm.Discussion and Conclusion. It has been found that the adhesion strength of a chrome coating to a copper alloy substrate increased laser irradiation at a radiation power density of 150 MW/m2. This was due to the formation of a transition region 2–4 μm deep in the contact zone with a structure consisting of sections of mutually insoluble solid solutions based on chromium and copper. Based on the analysis of the copper —chromium state diagram and the model of the temperature field under laser irradiation of the chromium coating, it was suggested that contact melting occurred in the transition zone from the coating to the copper substrate. It was shown that thermostrictive stresses, the calculated quantitative values of which were about 320 MPa, had an initiating effect on the observed processes of structure formation in the laser irradiation zones. It was found that such a level of stresses arising in copper alloys under laser irradiation was sufficient for plastic deformation and dynamic recrystallization of the metal and contributed to the formation of a fine-grained structure (4.5–5.0 μm) with an initial grain size of 25 μm. An analysis of the results of studies of irradiated compositions "coating — copper substrate" allowed us to conclude that they expanded the technological capabilities of the laser method of hardening materials and ensure guaranteed high performance of irradiated products with coatings

Multi‐Functional Self‐Sensing Electronic Gasket for Structural Health Monitoring of Transportation Pipelines

AbstractIn advancing “smart city” initiatives, multi‐functional sensing devices are crucial for the structural health monitoring (SHM) of key infrastructures. This study presents a self‐sensing sealing electronic gasket (e‐gasket) featuring multi‐modal interdigitated‐electrode‐based sensors for underground pipeline damage assessments, via simultaneously detected distribution information of contact pressure and relative humidity (RH). Detecting performance is enhanced through functional surface coatings and optimized pore size of the porous foam layer. An equivalent decoupling model for precise detection is established by analyzing the electrical responses of capacitance and impedance, and a rough estimation method relying on relative response is investigated to reduce the energy consumption and enhance monitoring efficiency. It demonstrates excellent multi‐modal sensing capabilities, repeatability, and stability over the long term. Experimental results verify the effectiveness in condition detection, fault classification, damage severity assessment, and early warning functions of the e‐gasket, enabling comprehensive SHM.

A sulfobetaine containing-polymethylmethacrylate surface coating as an excellent antifouling agent against Chlorella sp

Biofouling represents one of the major issues in Photobioreactors (PBRs) for microalgae cultivation. At this aim, a series of zwitterionic-containing polymethylmethacrylate (PMMA) co-ter-polymers, differing in the molar percentage of sulfobetaine (SBMA)- and 2-hydroxyethylmethacrylate (HEMA) components were designed as antifouling (AF) potential coatings for inner PMMA surface of photobioreactors (PBRs). Among these, the sample named PSBM, P(HEMA-co-MMA-co-SBMA), showing the best film capabilities on PMMA slides, was selected, characterized and its AF activity investigated. High transparent and thin PSBM films, as confirmed by AFM and optical transparency investigations, were obtained by a simple drop-casting procedure using a basic isopropylalcohol/water mixture. AFM images of raw PSBM and PSBM films clearly indicate that a conformational change occurred upon treatment with electrolytes. PSBM was further characterized by ATR-FTIR Spectroscopy, Dynamic Light Scattering, X-Ray Photoelectron Spectroscopy, Thermogravimetric analysis, Differential Scanning Calorimetry and Static Water Contact Angle (WCA) investigations. Consistent with hydrophilic behavior, the PSBM surface provided a WCA of 60.9 ± 0.8° which, interestingly, decreased to 27.7 ± 1.2° after immersion in electrolyte culture media. PSBM films displayed a high satisfactory AF behavior in that a rare or no cell adhesion was observed when placed for 7 days in a suspension of the green microalga Chlorella sp. For comparison, the experiments were carried out with untreated and rough PMMA surfaces.

Revealing the Surface and In-Depth Operational Performances of Oxygen-Evolving Anode Coatings: A Guideline for the Synthesis of Inert Durable Anodes in Metal Electrowinning from Acid Solutions

The electrochemical performances of an oxygen-evolving anode produced by the reactivation of waste Ti substrate by a typical IrO2-Ta2O5 coating are correlated to the textural (non)uniformities of the coating and its exhaustion state. Coating degradation is considered operational loss of the activity in a metal electrowinning process. It was found that (pseudo)capacitive performances can vary over the coating surface by 20–30% and depend on the type of dynamics of the input perturbation: constant through cyclic voltammetry (CV) or discontinuous time-dependent through electrochemical impedance spectroscopy (EIS). CV-EIS data correlation enabled profiling of the capacitive properties through the depth of a coating and over its surface. The correlation was confirmed by the findings for the analysis of coating activity for an oxygen evolution reaction, finally resulting in the reliable proposition of a mechanism for the operational loss of the anode. It was found that the less compact and thicker coating parts performed better and operated more efficiently, especially at lower operational current densities.

Highly reflective ZrC-Cu-based metal matrix composite coatings deposited via cold-spray for laser protection applications

Lasers are very powerful and can produce high temperatures, capable of melting materials when projected with an appropriate power, exposure time, distance, and beam width. High energy lasers are used for attacking enemy aircraft and missiles; however, the same threat is inevitable to the allied aircraft and missiles. Surface coatings have proven to be a viable solution to reduce damage from such laser attacks. In the present work, ZrC-Cu-based highly reflective coatings were deposited on Al-6061 alloy using the cold spray to develop laser damage resistance. Microstructural characterization, XRD, micro-hardness, reflectivity measurements, and laser ablation tests were conducted on the developed materials. The results showed improved ceramic retention and mechanical properties along with minimal porosity in the coating with increasing ZrC content in the feedstock. Additionally, the XRD analysis revealed that Cu-ZrC composite coatings could be produced by cold spray, without decarburisation of ZrC or oxidation of Cu. Owing to the exceptional purity in coatings, highly reflective coatings were obtained. At the target wavelength of 1080 nm, Cu-30 %ZrC composition achieved a remarkable reflectivity of 75 % (85 % of bulk copper). The coatings with compositions of Cu-30 %ZrC, Cu-50 %ZrC and Cu-70 %ZrC remained undamaged under laser irradiation, whereas Cu-85 %ZrC exhibited a laser ablation pit. These findings provide valuable insights into developing optimized ZrC-Cu coatings against laser irradiation.

Preparation and tribological properties study of a novel self-lubricating Alumina-based composite coating

A self-lubricating composite coating Al2O3/C was designed and sprayed via atmospheric plasma spraying (APS), in order to endow the alumina coating with certain lubricating properties under room temperature conditions. The raw feeding powders of boehmite-alumina-graphite (AlO(OH)/Al2O3/C) with particle sizes of 30–50 µm were prepared through hydroxylation treatment, physical stirring, and spray granulation process. The tribological properties of the Al2O3/C composite coating were systematically studied using a CSM friction tester. The prepared Al2O3/C composite coating exhibited fewer defects, lower coefficient of friction (COF), and slighter adhesion wear degree compared to single-component Al2O3 coating. The graphite lubrication film was discovered on both the worn surface of the composite coatings and the friction pair after friction. The existence of the graphite lubrication film decreased the COF, and the reduction extent depended on the load, with a maximum reduction of 55 %. The composite coatings presented the best tribological properties when sliding against Si3N4 balls at a higher load (5 N) because of the diverse wear mechanisms and the influence of graphite lubrication film, resulting in a reduction in the COF and wear rate by approximately 48 % and 11 times respectively. In addition, part of γ-Al2O3 in the Al2O3/C composite coating transformed into α-Al2O3 after the friction test. But the Al2O3 coating remained phase stable, with no phase change occurring before and after the friction. The transformation from the γ-Al2O3 to the α-Al2O3 phase was positive as for the tribological performance. It could reduce the COF as well as improving the thermal conductivity and mechanical properties of the coating.