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Quasi-continuous-wave laser surface melting of aluminium alloy: Precipitate morphology, solute segregation and corrosion resistance
摘要： A quasi-continuous wave laser surface melting is performed on 2219 aluminium alloy to improve the corrosion resistance. The fast cooling rate and the multi-directional solidification behavior of the process transform large and long-chained constituent particles into fine and isolated circular precipitates with alleviated solute segregation. The improved corrosion resistance is due to formation of low-flaw-density passive film, reduction of the driving force for corrosion and improvement of the re-passivation capability of the modified surface. The large and long-chained constituent particles are the preferred sites for corrosion initiation and propagation.
关键词： C: Segregation,B: Polarization,C: Pitting corrosion,A: Aluminium,B: EPMA
更新于2025-11-28 14:24:20
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Wear and Corrosion Resistance of Al0.5CoCrCuFeNi High-Entropy Alloy Coating Deposited on AZ91D Magnesium Alloy by Laser Cladding
摘要： In order to improve the wear and corrosion resistance of an AZ91D magnesium alloy substrate, an Al0.5CoCrCuFeNi high-entropy alloy coating was successfully prepared on an AZ91D magnesium alloy surface by laser cladding using mixed elemental powders. Optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction were used to characterize the microstructure of the coating. The wear resistance and corrosion resistance of the coating were evaluated by dry sliding wear and potentiodynamic polarization curve test methods, respectively. The results show that the coating was composed of a simple FCC solid solution phase with a microhardness about 3.7 times higher than that of the AZ91D matrix and even higher than that of the same high-entropy alloy prepared by an arc melting method. The coating had better wear resistance than the AZ91D matrix, and the wear rate was about 2.5 times lower than that of the AZ91D matrix. Moreover, the main wear mechanisms of the coating and the AZ91D matrix were different. The former was abrasive wear and the latter was adhesive wear. The corrosion resistance of the coating was also better than that of the AZ91D matrix because the corrosion potential of the former was more positive and the corrosion current was smaller.
关键词： laser cladding,wear,AZ91D magnesium alloy,high-entropy alloy coating,corrosion
更新于2025-11-21 11:24:58
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Laser Welding of Dissimilar Metal Joint of 6061 Al Alloy and Al Matrix Composite
摘要： In this paper, dissimilar metal joints of 6061 aluminum alloy and aluminum matrix composite material are investigated by laser welding. TiB2 particles were added into the lap joint. The welding process, microstructure, and the corrosion properties of welding joints are examined. The results demonstrate that the selected optimization process parameters are laser power 6 kW, welding speed 0.6 mm/s, pulse width 11.5 ms, and laser frequency 4.5 Hz. There are a few obvious pores in the molten pool. Al2Ti, Fe2Si, and Al0.5Fe3Si0.5 are present in the microstructure. During the welding process, some TiB2 particles are decomposed and reacted with molten Al. Other TiB2 particles are nucleated and solidi?ed, and the excess TiB2 particles are pushed to the grain boundaries by molten Al. TiB2 particles are wetted well by molten matrix metal. The corrosion resistance of alloys in di?erent conditions decreased in the following order: the weld beam >6061 Al > AMC.
关键词： aluminum matrix composite,laser welding,TiB2 particles,microstructure,6061 aluminum alloy,dissimilar metal joints,corrosion properties
更新于2025-11-21 11:18:25
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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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Excellent corrosion resistance of graphene coating on copper due to the low defect overlapping structure
摘要： Nowadays, ultra-thin graphene coating can provide considerable resistance against corrosion for various metals, however, there is great variability and contradictory in corrosion resistance mechanism of graphene coating reported in different studies. In this work, the anti-corrosion behaviors of graphene coatings with different defect values on the copper surface were investigated systematically. The results indicated that all graphene coated Cu exhibited superior corrosion resistance than heat treated Cu, regardless of the layer number of graphene. Particularly, anti-corrosion performance of bi-layer graphene coating was the most effective, the corrosive medium transferred a long way to reach the interface between Cu and graphene. The corrosion resistance for mono-layer graphene was inferior to bi-layer graphene, and poor corrosion resistance for multi-layer graphene was due to the high value of defects increasing the corrosion pathways, which leads to easier transfer for the chloride ions among defects. Consequently, the corrosion resistance ability of graphene coatings was mainly determined by the defect density other than the layer number, multi-layer graphene coating may not behave better anti-corrosion performance if it contained a high value of defect.
关键词： graphene,galvanic corrosion,layer number,SVET,CVD,defect
更新于2025-11-21 11:08:12
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Silicon Corrosion in Neutral Media: The Influence of Confined Geometries and Crevice Corrosion in Simulated Physiological Solutions
摘要： Silicon (Si) based implantable components are widely used to restore functionalities in the human body. However, there have been reported instances of Si corroding after only a few years of implantation. A key parameter often overlooked when assessing Si stability in-vitro, is the added constricting geometries introduced through in-vivo implantation. The influence of crevices and confined solutions on the stability of Si is presented in this study, considering two simulated physiological solutions: 0.01 M phosphate buffered saline (PBS) and HyClone Wear Test Fluid (WTF). It was found that Si is highly vulnerable to corrosion in confined/crevice conditions. High pitting corrosion susceptibility is found in a crevice, whereas a dissolution rate of ca. 3.6 nm/h at body temperature occurred due to local alkalization within a confined cathodic area. The corrosion rates could be increased by elevating the temperature and yielded linear Arrhenius relations, with activation energies of 106 KJ/mol in 0.01 M PBS and 109 KJ/mol in HyClone WTF, corresponding to a phosphorous-silicon interaction mechanism. Phosphorous species favored corrosion and contributed to enhanced Si dissolution, while chlorides were not so influential, and applied anodic potential induced pseudo-passivation. These results highlight the importance geometrical configurations can have on a material’s surface stability.
关键词： Silicon,Confined geometries,Corrosion,Physiological solutions,Implantable devices,Phosphorous-silicon interaction,Crevice
更新于2025-11-14 15:19:41
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Preliminary analysis on thermodynamic and thermo-economic performance of a solar CPC-KCS hybrid system
摘要： Using solar collectors to actuate Kalina cycle system (KCS) for electricity generation has been an attractive way to take advantage of solar energy. Most of the existing research is about KCS integrated with flat plate collector, evacuated tube collector, or concentrating collectors; however, little research focuses on the KCS powered by compound parabolic concentrator (CPC). Considering the merits of CPC, a Kalina 11 cycle system which is directly powered by CPC, named as solar CPC–KCS hybrid system is studied as the research object. Energy, exergy and thermo-economic models are established to estimate the system performance by varying the solar radiation, evaporating temperature and concentration of working fluid. Results show that higher evaporating temperature improves thermal and exergy efficiency. There are optimal values of Te for maximum wnet, is, Te,opt = 422.15, 434.15, and 446.15 K, respectively, at Xr = 0.95, 0.93, and 0.91; while Te,opt = 443.15, 437.15, and 425.15 K at Xb = 0.8, 0.7, and 0.6. Higher Xr and lower Xb is generally favorable for system performance. But when Te ≥ 422.15 K, lower Xb is not beneficial to ηex improvement anymore. Additionally, once evaporating temperature exceeds 439.15 K, it is cost-effective to install a superheater to avoid erosion potential risk.
关键词： Kalina cycle,corrosion potential,thermo-economic analysis,compound parabolic concentrator
更新于2025-09-23 15:23:52
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A Review on Recent Trends in Surface Coatings
摘要： Corrosion of the components is a predominant factor which controls the life of metallic parts. Metals parts of various structures are often subjected to damage due to corrosion driven failures causing loss of functionality and dimensions. In order to reduce corrosion, there are two ways one is introducing new materials and the other is improving the existing materials by adding alloying materials or by surface coating techniques. Surface coatings are a feasible way to enhance the corrosion resistance of metallic materials, thus expanding the life span of the metal components. Aim of this paper is to draw comparison between various coating techniques and analyze which surface coating technique and coating materials improves the corrosion resistance of the materials. Further, in this review paper coat materials on the base material by mostly cold spray and plasma spray techniques. So, these two surface coating modification techniques are discussed in detail.
关键词： coatings,Corrosion,wear
更新于2025-09-23 15:23:52
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Corrosion fatigue properties of narrow gap laser welded 301L stainless steel
摘要： In this paper, the corrosion-fatigue behavior of 301L stainless steel (SS) welded joints using narrow gap laser wire welding under the different stress ratio and concentrations of Cl? has been investigated. Corrosion fatigue life curve (S-N) under different conditions was tested and fitted to obtain the fatigue limit. The microstructures and fracture surfaces of specimens were examined by optical microscopy (OM) and scanning electron microscopy (SEM). EBSD results have shown that chromium depletion in the weld heat-affected zone (HAZ) contributes to the decrease of corrosion fatigue properties in the HAZ.
关键词： 301L,chromium depletion,corrosion fatigue
更新于2025-09-23 15:23:52
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Effects of coverage layer on the electrochemical corrosion behaviour of Mg-Al-Mn alloy subjected to massive laser shock peening treatment
摘要： Effects of coverage layer on electrochemical corrosion behaviour and pitting morphologies of Mg-Al-Mn alloy subjected to massive laser shock peening (LSP) treatment were investigated by potentiodynamic polarisation test, electrochemical impedance spectroscopy (EIS), and scanning electron microscope (SEM) observations. Microstructures of Mg-Al-Mn alloy subjected to massive LSP treatment were also characterized. Results showed that LSP induced an obvious improvement in electrochemical corrosion resistance with increasing coverage layer. Even in a higher corrosive solution concentration, LSP could still prevent corrosion to some extent. The improvement in electrochemical corrosion resistance was due to the grain refinement and compressive residual stress induced by massive LSP treatment. Finally, the influence mechanism of the coverage layer on electrochemical corrosion behavior of Mg-Al-Mn alloy was revealed.
关键词： Microstructure.,Electrochemical corrosion,Mg-Al-Mn alloy,Coverage layer,Laser shock peening
更新于2025-09-23 15:23:52