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Effect of graphene on corrosion resistance of Micro-arc oxidation coatings on 6061/7075 dissimilar laser-MIG hybrid welded joint
摘要： Corrosion behavior of a laser-metal inert gas hybrid (Laser-MIG) welded joint with dissimilar aluminum alloys was investigated. Micro-arc oxidation (MAO) coatings with and without graphenes were prepared on the surface of the welded joint. The effects of graphenes on the structure and corrosion resistance of the MAO coatings were studied. The welded joint was divided into five zones to investigate corrosion inducements in different zones. The heat-affected zone of 7075Al (7-HAZ) was found to be most susceptible to corrosion. Although the substrates in different zones had heterogeneous microstructures and phase compositions, the MAO coatings in different zones displayed relatively uniform surface morphology, structure, and phase composition. The MAO treatment significantly improved the corrosion resistance of welded joints. In addition, ceramic-graphene composite coatings exhibited slightly better corrosion resistance than a simple coating without graphenes due to structural changes in the coating.
关键词： Corrosion resistance,Aluminum,Graphene,Laser-MIG hybrid welding,Micro-arc oxidation
更新于2025-11-21 11:18:25
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Preparation and properties of duplex NI-P-TIO <sub/>2</sub> /NI nanocomposite coatings
摘要： Duplex Ni-P-TiO2/Ni coatings were deposited on the brass substrate by using two baths. Ni-P-TiO2 nanocomposite coatings were electroplated as the outer layer on the Ni-plated brass substrate by adding transparent TiO2 sol (0–50 mL/L) into the Ni-P plating solution. The microstructure, mechanical property and corrosion resistance of the duplex Ni-P-TiO2/Ni nanocomposite coatings were systemically investigated. The results show that the interface of duplex coating was uniform and the adhesion between two layers was extremely good. The microhardness of duplex Ni-P-12.5 mL/L TiO2 /Ni coating was ～616 HV50 compared to ～539 HV50 of Ni-P /Ni coating and ～307 HV50 of single Ni coating. Meanwhile, the wear resistance and the corrosion resistance of the duplex nanocomposite coating have also been improved remarkably compared with single Ni coating. However, adding excessive TiO2 sol (more than 12.5 mL/L) caused the agglomeration of TiO2 nanoparticles and led to a porous structure in the outer layer, resulting in the deterioration of coating properties.
关键词： Nanocomposite coatings,mechanical property,corrosion resistance.
更新于2025-09-23 15:23:52
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A novel growth strategy of TiO<sub>2</sub> anodic films using surface residual stress as driving force
摘要： The relationship between residual stress and growth behavior of anodic titanium oxide films (TiO2) was investigated in terms of defect chemistry and the nanocrystalline materials thermodynamic. The results showed that the surface residual stress can be controlled by acting on the duration of the surface mechanical attrition treatment (SMAT). When samples are processed by grinding for 30 min, the residual stress value reaches a maximum of 73.13 MPa, approximately 7.2 times higher than the one obtained with untreated sample. Under these conditions, the thickness of the anodic film was about 1200 nm, three times that of the TA2 anodic film. Furthermore, the results of electrochemical tests showed that following the surface mechanical attrition treatment, the anodic film show lower density vacancies, higher resistance to the diffusion of Cl-, higher density, and an improved corrosion resistance when compared to TA2. Generally speaking, the growth behavior of the anodic film can be improved by identifying the suitable residual stress.
关键词： Surface mechanical attrition treatment,Anodic oxidation,Corrosion resistance,Growth mechanism
更新于2025-09-23 15:23:52
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Light Metals 2014 (Grandfield/Light) || N-SiC Side Lining - Variations of Materials Structure
摘要： The key process in fabrication of Nitride bonded silicon carbide side lining of reduction pots is the reaction between Nitrogen and Silicon. Silicon may react with Nitrogen in solid, liquid and gaseous phase. The reaction is strongly exothermal. Almost all N-SiC refractory materials of more or less big shapes have the gradients of porosity from middle to the edges. The reason for these gradients may be the overheating of the middle part of shapes, compared to near surface layers, due to the exothermal effect and consequent increased concentration of volatile Silicon. Volatile Silicon tends to move to areas of lower temperature and the gradients of porosity are 1-2 %, but sometimes it may reach 5-7%. The problems with side lining of reduction pots may be because of the design of the pots, due to the overheating of the bath, yet the structure of N-SiC materials might be also critical.
关键词： corrosion resistance,side lining,N-SiC refractory
更新于2025-09-23 15:22:29
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Synergistic effect of Ag and ZnO nanoparticles on polyaniline incorporated epoxy/2pack coatings for splash zone applications
摘要： In this work, epoxy/2pack coatings containing polyaniline (PANI) in combination with Ag and ZnO nanoparticles have been synthesized. The nanoparticles were incorporated with bisphenol-A diglycidyl ether epoxy resin and polyamino-amide. The mechanical properties of the fabricated coatings, such as the pendulum hardness, scratch resistance, and impact strength, were studied. The composition of the fabricated coatings was confirmed by attenuated total reflectance infrared spectroscopy measurements. The thermal degradation and indentations were characterized through the use of differential scanning calorimetry and nano-indentation techniques, respectively. The surface morphology of the fabricated coatings was characterized using field-emission scanning electron microscopy. The synergistic effects of the Ag and ZnO nanoparticles on the corrosion resistance of the coatings after different exposure periods in 3.5% NaCl solutions were determined by electrochemical impedance spectroscopy. All the results were consistent with one another and confirmed that the addition of Ag and ZnO nanoparticles improved the mechanical properties of the coatings. This effect also led to a notable increase in the corrosion resistance of the PANI coatings.
关键词： Nanoparticles,Polyaniline,Nano-indentation,Corrosion resistance,Epoxy coatings,Surface morphology
更新于2025-09-23 15:22:29
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A highly efficient reduced graphene oxide/SnO2/TiO2 composite as photoanode for photocathodic protection of 304 stainless steel
摘要： A new photoanode RGO/SnO2/TiO2 nanocomposite material with a heterojunction structure was fabricated via hydrothermal method. The RGO/SnO2/TiO2 composite with different graphene content were prepared to explore optimal photoelectrochemical properties compared with pure TiO2. The morphology, structure and optical property of the obtained composite were characterized by TEM, FTIR, XRD and UV–vis. The photocathodic protection effect and anticorrosion properties of the nanocomposite for 304 stainless steel (304SS) were investigated by photocurrent density, open circuit potential, Tafel polarization curves and electrochemical impedance spectroscopy. The results show that compared with pure TiO2, the composite can provide an effective protection for 304SS not only under white light irradiation but also in the dark, and the optimal sample electrode potentials negatively shifted to ?590 mV under illumination. The possible photocathodic protection mechanism of the composite was also proposed.
关键词： Photocathodic protection,Corrosion resistance,Electrochemical properties,Graphene,Heterojunction
更新于2025-09-23 15:22:29
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Hybrid Laser Ablation and Chemical Modification for Fast Fabrication of Bio-inspired Super-hydrophobic Surface with Excellent Self-cleaning, Stability and Corrosion Resistance
摘要： Although laser ablation is considered as a facile technique to fabricate bio-inspired super-hydrophobic surfaces, the issue is that the initial laser treated metallic surfaces show super-hydrophilic property. It will take a long period to reach super-hydrophobic state under ambient air. It is reported that these super-hydrophobic surfaces could be easily damaged by thermal heating effect or interaction with other liquids, causing uncontrolled loss of super-hydrophobicity. In this study, a stable super-hydrophobic aluminum surface was rapidly fabricated via the hybrid laser ablation and surface chemical modification of (heptadecafluoro-1, 1, 2, 2-tetradecyl) triethoxysilane (AC-FAS). Surface morphology and chemistry were systematically investigated to explore the generation mechanism of super-hydrophobicity. The water contact angle of the treated surfaces can reach up to 160.6? ± 1.5? with rolling angle of 3.0? ± 1.0?, exhibiting perfect self-cleaning capability, long-term stability, and excellent chemical stability in acidic as well as alkaline solutions. The potentiodynamic polarization tests implied that the super-hydrophobic surfaces showed better anti-corrosion performance. This hybrid laser ablation and surface chemical modification are very time-saving and low-cost, which offers a rapid way for quantity production of super-hydrophobic surface on aluminum material.
关键词： nanosecond laser,bioinspiration,corrosion resistance,chemical stability,self-cleaning,super-hydrophobic,long-term stability
更新于2025-09-23 15:22:29
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Manufacturing profile-free copper foil using laser shock flattening
摘要： Copper foil is a key material of printed circuit boards and plays an important role in the conductance of electric circuits and interconnection of electronic components. When high-frequency signals were transmitted in rough copper foil wires, the conductor resistance, wire loss, and signal loss increased because of the skin effect. To reduce the negative influence of the skin effect and improve the quality of the copper foil, a laser shock flattening (LSF) method was proposed to manufacture profile-free copper foil with high performance. It was concluded that the better flattening effect for large-area profile-free copper foil could be achieved at a pulse energy of 0.25 J and an overlap rate of 25%, and its surface roughness decreased by 67.0% from 52.1 nm to 17.2 nm. Subsequently, to determine the mechanism for the flattened deformation of copper foil induced by LSF, the microstructures of the copper foil before and after flattening were characterised using transmission electron microscopy. A higher dislocation density and a few deformation twins were found in the profile-free copper foil. Ultimately, nano-indentation, micro-tensile, and electrochemical corrosion tests indicated that the mechanical properties and corrosion resistance of the copper foil were significantly improved by LSF. This technique would enable the successful fabrication of large-area profile-free copper foil with high performance for the emerging applications of ultra-high-frequency signal communication and printed circuit board manufacture.
关键词： Corrosion resistance,Mechanical properties,Flattened deformation mechanism,Microstructures,Laser shock flattening,Profile-free copper foil
更新于2025-09-23 15:21:01
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Effect of laser surface melting on surface integrity of Ala??4.5Cu composites reinforced with SiC and MoS2
摘要： Two types of composites were prepared with Al?4.5Cu alloy as a matrix using stir casting method. One was reinforced with 10 wt.% of SiC and 2 wt.% of MoS2. The other was reinforced with 10 wt.% of SiC and 4 wt.% of MoS2. Their surfaces were remelted using a CO2 laser beam with an objective to study the influence of laser surface melting (LSM). The topography, microhardness, corrosion resistance and wear resistance of the laser melted surfaces were studied. Overall surface integrity after LSM was compared with as-cast surface. LSM enhanced the microhardness and wear resistance of the surface in each case. Porosity of the laser melted surface was low and corrosion resistance was high. Thus, LSM can be conveniently applied to enhancing the surface integrity of the aluminium composites. However, there is an optimum laser specific energy, around 38 J/m2 in this study, for obtaining the best surface integrity.
关键词： microhardness,aluminium composites,laser surface melting,corrosion resistance,molybdenum disulfide,silicon carbide
更新于2025-09-23 15:21:01
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Enhancement of the surface properties of selective laser melted maraging steel by large pulsed electron-beam irradiation
摘要： The present work aimed to decrease the surface roughness of maraging steel (MS) by selective laser melting (SLM) using large pulsed electron-beam (LPEB) irradiation as a post-treatment. The MS samples were fabricated using different combinations of laser power, scanning speed, hatch distance, and build angle. The morphological features, surface roughness, phase content, and corrosion resistance of the MS samples in their as-fabricated (ASF) state were compared after LPEB irradiation. The ASF SLM-MS samples exhibit the presence of partially melted particles that spread over the entire surface and many cracks in both the longitudinal and transverse directions. A higher arithmetical mean height (Sa: 2-17 μm), large variations in Sa measured at various locations, and a strong dependence of Sa on build angle were also observed. Post-treatment by LPEB irradiation removed the partially melted particles, while reflow of the molten mass filled the cracks and voids and facilitated the formation of a uniform surface with a bright metallic finish. This has resulted in a significant decrease in Sa (0.50-4.50 μm) and a smaller variation in Sa measured at different locations. Body-centered cubic α-martensite was the predominant phase for the ASF SLM-MS samples, along with a small fraction face-centered cubic γ-austenite phase. After LPEB irradiation, the martensite was reverted to the austenite phase. The corrosion resistance of the LPEB-irradiated samples was moderately better than that of the ASF SLM-MS samples. The uniform surface morphology, removal of partially melted particles, absence of pores and cracks, decrease in Sa, and moderate improvement in corrosion resistance suggests that LPEB irradiation can be used as a post-treatment for SLM-MS samples.
关键词： corrosion resistance,large pulse electron beam irradiation,maraging steel,Selective laser melting,surface roughness
更新于2025-09-23 15:19:57