15 August 2025, Volume 58 Issue 8

    

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  MXene-Modified Anti-Corrosion Coatings: Surface/Interface Regulation and Anti-Corrosion Mechanisms

  LI Guanting, YAN Minglong, ZHAO Wenjie

  Materials Protection. 2025, 58(8): 1-15. https://doi.org/10.16577/j.issn.1001-1560.2025.0128

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  In order to address the issue of metal corrosion in marine environments，applying organic coatings to the surfaces of marine equipment is a proven and effective strategy.However，organic coatings are inevitably eroded by corrosive media during service，leading to gradual degradation of their performance.MXene nanosheets have been widely used to enhance the corrosion resistance of organic coatings due to their large specific surface area，high impermeability and excellent interfacial compatibility.Currently，research on the corrosion protection of MXene-modified organic coatings primarily focuses on surface and interfacial design and their anti-corrosion mechanisms.Based on an overview of research progress in MXene-modified organic coatings，this paper discussed the key factors influencing the corrosion resistance of the composite coatings and their protection mechanisms.Finally，future development directions for MXene-modified organic composite coatings were proposed.
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  Research Progress on Quantum Dots and Their Reinforced Composite Coatings for Metal Corrosion Protection

  ZHANG Heng, YAN Minglong, WU Yangmin

  Materials Protection. 2025, 58(8): 16-30. https://doi.org/10.16577/j.issn.1001-1560.2025.0129

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  Quantum dots have attracted much attention due to their excellent biocompatibility，high specific surface area，ease of surface functionalization and diverse preparation methods.In recent years，significant progress has been made in the application of quantum dots in the field of corrosion protection.This paper first outlined various types of quantum dots，and conducted a comparative analysis of common synthesis technologies along with their respective advantages and disadvantages.Subsequently，the performance of quantum dots as corrosion inhibitors in various corrosive environments was summarized，along with the current research status of their application as nano-fillers to enhance the anti-corrosion properties of polymer coatings.Finally，this paper elucidated the corrosion protection mechanisms of quantum dots and their functionalized modified coatings.The current challenges and future development trends of quantum dots in the field of corrosion protection were discussed.
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  Study on the Corrosion Mechanism of Pseudomonas aeruginosa on TA2 Pure Titanium

  RAN Boyuan, QIANG Yujie, YANG Haoxuan, JIN Ying

  Materials Protection. 2025, 58(8): 31-43. https://doi.org/10.16577/j.issn.1001-1560.2025.0130

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  With the deepening of the strategy of marine resources development，the wide application of pure titanium with excellent corrosion resistance in marine engineering equipment is facing the severe challenge of microbiologically influenced corrosion (MIC).In this study，the microbial corrosion behavior of pure titanium was investigated through bacterial culture，electrochemical testing，surface morphology characterization and corrosion product analysis with the dominant marine bacterial species Pseudomonas aeruginosa (P.aeruginosa) as the research object.This study systematically revealed the corrosion failure mechanism of TA2 pure titanium under the action of biofilm.Results showed that P.aeruginosa accelerated the corrosion process of TA2 pure titanium.At the initial stage of immersion in a bacterial-containing environment，the biofilm temporarily protected the substrate through the physical barrier effect.With the prolongation of immersion time，the biofilm detached，and the depth of surface pitting increased compared with that in the sterile environment，with the decrease of charge transfer resistance and the increase of corrosion current density.On the one hand，the TiO2 content in the surface passivation film decreased in the bacterial environment，and the formation of metastable Ti2O3/TiO reduced the compactness of the film layer，formed local defects and induced pitting initiation.On the other hand， P.aeruginosa might mediate electron transfer between bacteria and metals by secreting electron carriers such as pyocyanin (PYO).Generally，the research results provide theoretical support for the corrosion prediction of marine equipment and the development of microbial protection technologies，which is of great significance to enhance the service safety and economic efficiency of marine engineering materials.
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  Tribocorrosion Behavior and Mechanisms of AlCoCr_1.8Fe_0.2Ni_2.1 Multi-Principal Element Alloy in Simulated Seawater Environment

  SU Yangyang, PANG Xuming, ZHOU Chengshuang, PU Jibin, CHEN Chen, QIN Xuezhi, YAO Hongwei

  Materials Protection. 2025, 58(8): 44-50. https://doi.org/10.16577/j.issn.1001-1560.2025.0131

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  To address the common issue of tribocorrosion coupling failure of metallic moving components in marine environments，this study designed and developed a wear/corrosion-resistant multi-principal element alloy (MPEA).The AlCoCr1.8Fe0.2Ni2.1 MPEA composition was optimized via CALPHAD phase diagram calculations，and the as-cast alloy was fabricated through vacuum melting.Results showed that the alloy had a FCC＋B2＋BCC three-phase structure，forming a microstructure consisting of FCC network skeleton and nanoscale BCC/B2 coherent structures.In comparison with the classical AlCoCrFeNi2.1 MPEA，the AlCoCr1.8 Fe0.2 Ni2.1 alloy exhibited a 100 MPa enhancement in yield strength，a 120 HV increase in hardness，a 30%reduction in tribocorrosion rate in 3.5%(mass fraction) NaCl solution，and an 84%decrease in corrosion current density，accompanied by significantly improved passive film stability.These improvements were attributed to the higher Cr content promoting coherent precipitation of Cr-rich nanophases within the B2 matrix.The abundant coherent phase boundaries effectively impeded dislocation motion，thereby enhancing the alloy strength.Meanwhile，the abundant coherent phase boundaries also accelerated the surface repassivation rate，thereby further enhancing the alloy tribocorrosion resistance.This study provides novel insights into the design of metallic structural materials for marine engineering applications.
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  Study on the Influence of Different Marine Zones on Corrosion Behaviors of S460 Marine Steel in the South China Sea

  ZHANG Yue, MA Heng, XUE Jialiang, LEI Li, CUI Zhongyu

  Materials Protection. 2025, 58(8): 51-62. https://doi.org/10.16577/j.issn.1001-1560.2025.0132

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  The S460 steel produced via the new-generation thermomechanical controlled process (TMCP) exhibits superior fatigue resistance and better corrosion resistance，and is expected to be widely used in the field of wind power equipment.In this work，a six-month real-sea exposure test was conducted on S460 steel across four marine zone environments (atmospheric zone，splash zone，tidal zone，and full immersion zone) in the Sanya sea area.The corrosion behavior of S460 steel in different zone environments was studied by measuring corrosion rate，observing morphology and analyzing the composition of corrosion products.Results showed that after six months of real-sea exposure testing，the specimens in the splash zone exhibited the highest corrosion rate.The distinct environmental conditions across different marine zones significantly influenced the formation of corrosion products on the specimens.In particular，the sufficient oxygen in the splash zone was conducive to the formation of Fe3O4 on the specimens.In contrast，due to the periodic immersion of seawater，the electrolyte layer on the specimens in the tidal zone persisted，which promoted the formation of γ-FeOOH.All specimens exhibited localized corrosion on their surfaces.Specifically，the localized corrosion pits on the specimens in the atmospheric zone were small in diameter and depth and densely distributed，while the specimens in the splash zone showed obvious localized corrosion pits with greater depth.
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  Study on the Corrosion Resistance of Graphene Oxide/Melamine Phosphate Waterborne Composite Coatings

  ZHAO Bo, FENG Hanyu, SHU Xina, ZAN Lujun, TAO Haihua, QIU Huidong

  Materials Protection. 2025, 58(8): 63-68. https://doi.org/10.16577/j.issn.1001-1560.2025.0133

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  In order to study the corrosion resistance of graphene oxide/melamine phosphate waterborne composite coatings in marine environments，melamine phosphate was used to covalently functionalize graphene oxide，and the modified graphene oxide was added to waterborne polyurethane to prepare waterborne composite coatings of functionalized graphene oxide.The structure and microstructure were comparatively analyzed via Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM).Corrosion resistance salt spray tests，polarization curve measurements and adhesion strength tests were conducted.Results showed that when the mass ratio of graphene oxide to melamine phosphate in the composite was 1 ∶3 and the addition amount of modified graphene oxide was 0.8 g，the corrosion protection efficiency of the composite coating reached 99.78%.Meanwhile，the coating exhibited an adhesion strength of 4.09 MPa，with a 49%adhesion loss rate after 168 h of salt spray test.The coating's hardness was 5H.Contact angle measurements revealed that the addition of modified graphene oxide increased the coating’s contact angle from 77.3°±1.0° to 99.8°±0.6°.Overall，the graphene oxide/melamine phosphate waterborne coating exhibited excellent corrosion resistance，which was better than both pure melamine phosphate coatings and graphene oxide coatings.
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  Current Status of Application of Fractal Theory and Methods in Thermal Spray Coating Research

  WANG Rui, WANG Hai, LI Jiaqi, WANG Haidou, SUN Xiaofeng, MA Guozheng, LIU Jian, GUO yongming

  Materials Protection. 2025, 58(8): 69-79. https://doi.org/10.16577/j.issn.1001-1560.2025.0134

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  Thermal spraying technology is one of the key supporting technologies of remanufacturing, and the heterogeneous interface between thermal spray coating and substrate has a significant impact on the coating performance. As an effective means to characterize the morphology of complex structures, fractal has been widely used in the field of materials science. The surface of thermal spray coatings and the interface between substrate and coating inherently exhibit self-similarity and fractal characteristics, so it is of great significance to study thermal spray coatings using fractal theory and methods. In this paper, the fractal dimension characterization of spray coatings, bonding interfaces, coating properties, and coating deposition growth mechanisms was systematically reviewed. The quantitative relationship between surface fractal dimension and coating morphology was analyzed, providing a new method for investigating coating surface morphology and related issues. Furthermore, future research could focus on applying fractal theory to investigate the microscopic growth characteristics and crack initiation during the spreading behavior of sprayed molten droplets, to achieve coating quality control and solve practical bonding strength problems.
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  Research Progress on Surface Modification Technologies for Titanium-Based Anode

  HUANG Qiuling, CHEN Wenlong, GUO Li

  Materials Protection. 2025, 58(8): 80-90. https://doi.org/10.16577/j.issn.1001-1560.2025.0135

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  Titanium-based anodes are widely used in the chlor-alkali industry，electrocatalytic degradation of pollutants and other fields，due to their excellent performance in electrocatalytic activity and chemical stability.However，problems such as coating peeling and reduced electrocatalytic activity during long-term operation have limited their further application.This study summarized the advantages and limitations of mainstream surface modification technologies (including thermal decomposition，sol-gel，electrodeposition，plasma electrolytic oxidation，and vapor deposition) in optimizing surface morphology，increasing anode surface area and improving corrosion resistance and stability，and reviewed the characteristics and applicability of different modification methods.Results showed that the performance of titanium-based anodes was significantly influenced by material composition，interfacial bonding strength between the substrate and coating，and structural uniformity of the coating.The application of surface modification technologies effectively enhanced the catalytic efficiency and durability of anodes.Process optimization and the introduction of novel coating materials played a crucial role in extending anode service life.Future research on titanium-based anodes should focus on the composite application of coating material design and surface modification technologies to achieve an optimal balance between performance and cost，so as to provide support for the large-scale promotion of titanium-based anodes.
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  Research Progress on High-Temperature Fatigue Behavior and Failure Mechanisms of Austenitic Metallic Materials

  FENG Xubo, WANG Neng

  Materials Protection. 2025, 58(8): 91-100. https://doi.org/10.16577/j.issn.1001-1560.2025.0136

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  Austenitic metallic materials are widely used in the construction of ultra-supercritical thermal power and nuclear power units，due to their excellent mechanical and corrosion resistance properties.The temperature fluctuations caused by the start-stop and rapid load changes of thermal power units，as well as the flow-induced vibration and thermal stratification in the nuclear power units，can generate alternating stresses，leading to fatigue failure of materials.This article introduced the research progress on the high-temperature fatigue behavior of typical austenitic metallic materials used in power stations in recent years.The influence of temperature，load，microstructure，and specimen shape on the fatigue performance of austenitic metallic materials was systematically reviewed under both high-temperature air and high-temperature and high-pressure water environments.Besides，the high-temperature fatigue behavior and failure mechanisms of austenitic metallic materials under different environments were systematically elucidated，and the specific factors affecting the fatigue life of austenitic metallic materials were comprehensively summarized，which established a theoretical basis and methods for analyzing fatigue failure behavior in high-temperature metallic materials used in advanced power generation units.
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  Study on the Preparation and Performance of Photo-Curing Hydrophobic and Oleophobic Coatings Based on Micro-Nano Silicon-Based Composite Fillers

  CHENG Qian, SUN Mingzhu, LIANG Bin, HU Haodong, WANG Huaiyuan

  Materials Protection. 2025, 58(8): 101-107. https://doi.org/10.16577/j.issn.1001-1560.2025.0137

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  Hydrophobic and oleophobic surfaces exhibit outstanding liquid-repellent properties，making them highly promising for applications in corrosion resistance，self-cleaning and pipeline transportation and other fields.In this study，glass flakes (GF) were used as the substrate，GFSiO2 composite filler was obtained by hydrolysis of nano-SiO2 and GF through sol-gel method.The composite filler GF-SiO2-F with low surface energy and micro-nano structure was prepared by grafting perfluorodecyl groups onto the composite filler through chemical modification.Photocuring monomers were used as the binder，and GF-SiO2-F as the filler to prepare the photo-curing coating UV-GF-SiO2-F.The CH2I2 contact angle of this coating was 153°，and the H2O contact angle was 158°，demonstrating hydrophobic，oleophobic properties and self-cleaning properties.Moreover，the coating demonstrated outstanding durability and corrosion resistance，providing effective protection for materials in harsh environments.Mechanism research showed that by constructing composite filler to form micro nano rough structures and chemical modifications，the migrating perfluorodecyl groups on the surface of composit filler worked synergistically with the micro nano structures to trap air and form a stable air cushion，which significantly reduced direct contact between water/oil and the coating surface.As a result，the UV-GF-SiO2-F coating is hydrophobic and oleophobic.
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  Study on Tribological Properties of Solid-Liquid Composite Ball-Lubricated Surfaces

  TANG Weidong, YU Aibing, QIN Tuo, GUO Xufeng, YE Jiawang, ZHANG Jiawei

  Materials Protection. 2025, 58(8): 108-115. https://doi.org/10.16577/j.issn.1001-1560.2025.0138

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  To achieve solid-liquid composite lubrication on textured surfaces under oil-deprived conditions and improve the tribological performance of material surfaces，a solid-liquid composite ball-lubricated surface was designed and fabricated on a 45 steel substrate.Ball-ondisk friction and wear tests were conducted under oil-deprived conditions to compare the tribological performance of three types of textured surfaces: oil-containing pit surfaces，ball-lubricated surfaces，and solid-liquid composite ball-lubricated surfaces.The wear track cross-sections and worn surfaces were observed using a laser scanning confocal microscope and a thermal field scanning electron microscope.The lubrication process of the solid-liquid composite ball-lubricated surface was observed with a high-speed camera，and the lubrication mechanism was analyzed using an energy dispersive spectrometer (EDS).Results showed that the solid-liquid composite ball-lubricated surface could effectively reduce wear on the friction pair surface and improve the tribological performance of the material surface.Compared to the oil-containing pit surface and the ball-lubricated surface，the friction coefficient of the solid-liquid composite ball-lubricated surface reduced by 46.3%and 27.2%，respectively，and the wear amount decreased by 78.3%and 73.7%，showing a significantly lower friction coefficient and wear amount.The sintered lock ring in the pit could reduce wear at the pit opening，locking the ball in the pit and preventing it from rolling off during friction.The solid-liquid composite ball-lubricated surface combines the advantages of both liquid and solid lubrication，effectively reducing material surface wear and enhancing the tribological performance of the textured surface.
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  Study on the Superhydrophobicity and Wear Resistance of Modified SiO₂/Epoxy Resin/PDMS Coatings

  GU Xueyang, HU Ya, LIU Ying, LI Jingwang, YUAN Zefeng, SUN Jiageng, WANG Yu’an, RUAN Shicheng, TAO Zhijie, WU Lin

  Materials Protection. 2025, 58(8): 116-127. https://doi.org/10.16577/j.issn.1001-1560.2025.0139

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  In order to improve the hydrophobicity and wear resistance of polydimethylsiloxane (PDMS) coatings，KH-570 was used to modify amorphous SiO2 particles，which were used as fillers in the composite coatings to enhance the hydrophobicity of the coating.Epoxy resin E-51 was used to improve the wear resistance of the coating.The effects of filler content and preparation process on the hydrophobicity and wear resistance of the composite coatings were investigated.Results showed that KH-570 successfully modified the SiO2 particles，and the addition of KH-570-modified SiO2 particles enabled the PDMS coating to achieve superhydrophobicity with self-cleaning properties.It was determined that a filler content of 5%(mass fraction) KH-570-modified SiO2 particles，a mixing and stirring time of 20 min，and a curing time of 2 h resulted in a wear-resistant superhydrophobic coating with a static water contact angle of 154° and a water rolling angle of 2°.The addition of 0.4 g of E-51 improved the adhesion of the composite coating to grade 0 and reduced the wear percentage to 2.49%，with a static contact angle of 152.7°and a water rolling angle of 9°.The corrosion potential was－0.364 V，and the corrosion current was 1.331×10－7 A/cm2.The research results are expected to have important application prospects in fields such as marine anti-corrosion engineering，microfluidic devices，and smart surfaces.
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  Study on the Preparation of Diamond-Doped Micro-Arc Oxidation Coatings on Magnesium Alloys

  QI Huarong, FENG Jun, YUAN Shaohua, DENG Shengyong, CHENG Junjie, DAN Min

  Materials Protection. 2025, 58(8): 128-139. https://doi.org/10.16577/j.issn.1001-1560.2025.0140

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  In order to address the poor corrosion and wear resistance of magnesium alloys，diamond-doped micro-arc oxidation coatings were successfully prepared on the surface of magnesium alloys by doping different concentrations of nanodiamond particles into silicate-based electrolyte.The surface morphology，elemental distribution，phase composition，thickness，wear resistance，and corrosion resistance of the micro-arc oxidation coatings were characterized by scanning electron microscopy (SEM)，X-ray diffractometer (XRD)，eddy current thickness gauge，friction-wear tester and electrochemical workstation.Results showed that when the doping concentration of nanodiamonds was from 0 to 2 g/L，the pores on the surface of the coating were reduced，the surface porosity of the coating decreased，and the coating thickness increased.The porosity of the coating was reduced from 17.89%to 9.84%，and the thickness increased from 22.40 μm to 28.60 μm.The friction coefficient of the coating increased from 0.70 without doping to approximately 1.00，and the depth of the wear track was smaller，with fewer occurrences of surface coating delamination，showing improved wear resistance.The coating exhibited lower corrosion tendency，and its corrosion resistance was enhanced.
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  Effect of Grain Boundary Character Distribution Optimization on the Molten Salt Hot Corrosion Behavior of Nickel-Based Alloy N6 Welds

  CHAI Tingxi, LI Yinghui, YU Youjun, XU Hongtong

  Materials Protection. 2025, 58(8): 140-146. https://doi.org/10.16577/j.issn.1001-1560.2025.0141

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  In order to improve the molten salt corrosion resistance of the plasma arc welds of the nickel-based alloy N6，the welds were subjected to tensile deformation and heat treatment (referred to as GBE samples).The grain boundary character distribution (GBCD) was analyzed using Electron Backscatter Diffraction (EBSD) and Orientation Imaging Microscopy (OIM).A constant-temperature corrosion test at 900°C was conducted to study the effect of the grain boundary character distribution on the welds’resistance to molten salt corrosion.Results showed that after the weld samples underwent 6%tensile deformation，annealing at 1 000 °C，and an annealing time of 15 min，recrystallization occurred，resulting in grain refinement.The heat treatment process generated a large number of annealing twins，and the proportion of low ΣCSL grain boundaries in the welds increased to 57.3%.The welds underwent oxidation and sulfidation reactions in a high-temperature 75%Na2SO4-25%NaCl molten salt mixture.The surface corrosion characteristics of the weld samples were predominantly intergranular corrosion.The hot corrosion rate of the untreated samples (Non - GBE) was faster [0.848 4 mg/(cm2·h)] than that of the GBE samples [0.339 7 mg/(cm2·h)].The molten salt corrosion resistance of the nickel-based alloy N6 welds was significantly enhanced through tensile deformation and heat treatment.
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  Study on the Preparation and Tribological Properties of TiC Thin Films on Si₃N₄ Substrates

  WANG He, CHU Jianxiang, YAN Guangyu, WU Yuhou, CHEN Sibo, DAI Guangyuan

  Materials Protection. 2025, 58(8): 147-154. https://doi.org/10.16577/j.issn.1001-1560.2025.0142

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  In order to address the heating issue caused by the high friction coefficient in Si3N4 ceramic bearings during use，TiC thin films with carbon contents (atomic fraction) of 38.84%，63.90%，69.23%，and 78.04%were prepared on the surface of Si3N4 ceramic bearings using magnetron sputtering.The effect of carbon content on the microstructure and properties of the films was studied.The surface and cross-sectional morphology，as well as the composition of the films，were analyzed using scanning electron microscopy (SEM) and X-ray diffractometer(XRD).The film-substrate adhesion strength and tribological properties were evaluated through nano-scratch and friction-wear tests.Results showed that the TiC films exhibited a structure where amorphous carbon encapsulated the grains.As the carbon content increased，the TiC films displayed a preferred (111) orientation and gradually transformed into a structure without obvious preferred orientation.When the carbon content was 63.90%(atomic fraction)，the TiC film exhibited the highest film-substrate adhesion strength of 26.22 N.Compared to the friction coefficient of Si3N4(0.419)，the TiC film with a carbon content of 78.04%(atomic fraction) demonstrated a significantly lower friction coefficient of 0.047.The preparation of TiC films on the surface of Si3N4 ceramic bearings can effectively enhance the adhesion strength and reduce the friction coefficient.
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  Tribological Performance of HVOF-Sprayed YSZ-Modified NiCrBSi Coatings

  CHEN Chuanlong, YANG Rentao, DU Pengcheng

  Materials Protection. 2025, 58(8): 155-161. https://doi.org/10.16577/j.issn.1001-1560.2025.0143

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  NiCrBSi coatings prepared by high-velocity oxygen-fuel (HVOF) spraying are widely used in tribological and corrosive environments.To investigate the effect of the ceramic modification phase YSZ on the friction and wear behavior of NiCrBSi coatings，this study employed HVOF technology to fabricate modified NiCrBSi coatings with YSZ doping mass fractions of 5%，10%，15%and 20%.The microstructure，porosity and hardness of the coatings were characterized using scanning electron microscopy (SEM)，white light confocal microscopy and micro-Vickers hardness testing.The tribological properties of coatings with different YSZ contents were evaluated using a multi-functional wear tester.Results showed that after YSZ doping，the coating porosity significantly decreased from 2.4%(without YSZ) to approximately 0.1%.Since the microhardness of YSZ was lower than that of NiCrBSi，the microhardness of the coatings did not change significantly when the YSZ content was below 10%due to the reduction in porosity.However，when the YSZ content exceeded 10%，the microhardness decreased markedly.The wear mechanism of the NiCrBSi coating was characterized by a combination of fatigue wear and abrasive wear resulting from fatigue spalling.With the addition of YSZ，the fatigue wear characteristics of the NiCrBSi coatings were significantly reduced，leading to an improvement in wear resistance.Among the modified coatings，the one with 10%YSZ content exhibited the optimal wear resistance，which was 2.5 times that of the unmodified NiCrBSi coating.
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  Study on the Microstructure and Wear Resistance of WC10Co4Cr Coatings Sprayed by Miniaturized HVOF Equipment for Narrow Spaces of Hydroturbine

  XIE Changning, ZHANG Lu, LIU Gang, LI Yi, QIN Yuze, XIE Weiwei

  Materials Protection. 2025, 58(8): 162-171. https://doi.org/10.16577/j.issn.1001-1560.2025.0144

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  In order to address the issue of small angle spraying and low efficiency in the preparation of hard metal coatings in narrow spaces such as hydroturbine blades due to the large size of the gun head of commercial high velocity oxygen fuel (HVOF) equipment，a miniaturized HVOF system was developed.WC10Co4Cr hard metal coatings were prepared under different spraying angles using this miniaturized system.The effects of spraying angle on the coating’s microstructure，surface roughness，microhardness，bonding strength and abrasive wear resistance were investigated using scanning electron microscopy (SEM)，laser confocal microscopy，digital microhardness tester，universal material testing machine，and rubber wheel abrasive wear tester.These results were compared with coatings prepared using commercial HVOF equipment.Results showed that the phase composition of WC10Co4Cr coatings produced by both equipment types was similar，with WC as the primary phase，along with W2C and W phases produced due to the decomposition of WC.The porosity and surface roughness of the coatings decreased with an increase in spraying angle.At the same spraying angle，the coatings produced by the self-developed miniaturized equipment exhibited higher porosity and roughness compared to those produced by the commercial equipment.The deposition efficiency of the coatings decreased with a reduction in spraying angle，and the deposition rate of the commercial equipment significantly decreased when the spraying angle was below 30°.The microhardness，bonding strength，and abrasive wear mass loss of the coating sprayed at a 90° angle using the miniaturized equipment were 1 100.3 HV，52.5 MPa and 0.011 3 g，respectively，outperforming the coatings prepared by the commercial equipment at a 30° angle in terms of coating performance and powder deposition efficiency.Because the miniaturized equipment can spray vertically in narrow spaces，it is more suitable for spraying operations in narrow spaces compared to commercial equipment.
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  Influence Law of Film Formation Conditions on the Properties of Different Types of Raw Lacquers

  WEN Juanjuan, LIU Langlang, LI Yan, SUN Lei, LI Dongxu, CHEN Dawei

  Materials Protection. 2025, 58(8): 172-181. https://doi.org/10.16577/j.issn.1001-1560.2025.0145

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  As a natural coating，raw lacquer was once known as the "king of coatings".In this study，representative types of raw lacquer，including refined raw lacquer，transparent raw lacquer，black raw lacquer，and red raw lacquer，were selected as research objects.The films were formed using both drying and shade-drying methods，and the surface drying time，adhesion，and hardness of the films were investigated.The raw lacquer coatings were characterized by infrared spectroscopy and scanning electron microscopy to provide insights for the application and development of raw lacquer.Results showed that the dried films achieved surface drying within 2.5 h，with raw lacquer and black raw lacquer reaching surface reaching surface dryness in 1.5 h.The shade-dried films had a longer surface drying time，ranging from 8 to 12 h.The adhesion of the dried films ranged from grade 2 to 3，which was superior to that of the shade-dried films.The adhesion of the polished films was improved by 1 to 2 grades.The hardness of the shade-dried films ranged from HB to 2H，while the hardness of the dried films ranged from 2B to H.After drying treatment，the urushiol side chains underwent crosslinking，and the characteristic peak of the urushiol in the shade-dried raw lacquer weakened.The surface of the dried raw lacquer coatings was smoother and flatter compared to the shade-dried coatings，while the cross-section of the shade-dried raw lacquer coatings was more uniform.Heating treatment can improve the dryness and adhesion of raw lacquer coatings，while shade-drying treatment can enhance the hardness of the coatings.