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Surface & Coatings Technology
Elsevier Sequoia
Surface & Coatings Technology

Elsevier Sequoia

0257-8972

Surface & Coatings Technology/Journal Surface & Coatings TechnologySCIISTP
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    Microstructure and reaction mechanism of Ti-Al-C based MAX phase coatings synthesized by plasma spraying and post annealing

    Yu G.Ma H.He J.Yin F....
    11页
    查看更多>>摘要：? 2022 Elsevier B.V.This work explored the feasibility of fabricating thick Ti2AlC and Ti3AlC2 coatings by plasma spraying from Ti/Al/graphite agglomerates and post annealing. The phase transformation and microstructure evolution of the sprayed coatings annealed at 500–900 °C were proposed. The as-deposited coating exhibited a micro-laminated structure with mainly of (Ti, Al)Cx, Ti2AlC, residual Al and minor TixAly. The short reaction time of spraying process led to insufficient reaction in C@Ti-Al agglomerates, thus forming dominate (Ti,Al)Cx and limited amount of Ti2AlC. The phase in the coating changed little when annealing below 600 °C. As increasing temperature to 700 °C, both of Ti3AlC2 and Ti2AlC showed obvious growth but Ti3AlC2 was predominate. Under higher temperature (>700 °C), Ti3AlC2 in the coating decreased while Ti2AlC grew apparently. The residual Al, transition phase (Ti, Al)Cx and high temperature annealing were main factors to promote the formation of Ti2AlC phase in sprayed coatings. The as-annealed coating showed increasing hardness with elevated temperature because of the formation of Ti2AlC, reduced pores and homogenous structure. This study implied that element agglomerates would be an effective alternative of expensive MAX phase powders as feedstock for plasma spraying MAX phase coatings.
      原文链接:
    • NSTL

    Synthesis of ZrB2 strengthened Ni–W composite coating and study of its mechanical characters and anti-corrosion performance

    Li H.He Y.Luo P.Li Z....
    5页
    查看更多>>摘要：© 2022 Elsevier B.V.In this experiment, we prepared a series of Ni-W/ZrB2 composite coatings with different dosage gradients of dispersed phase granules by pulse electrodeposition. The suspension properties and agglomeration of particles in the bath were studied in detail by particle size analysis and Zeta potential testing. The XRD, EDS and XPS were adopted to explore the phase composition, element distribution and chemical state of the matrix, The SEM and AFM were used to characterize the apparent morphology and micro-roughness of the composite matrix. The wear resistance of the composite coating was evaluated by reciprocating friction. The results pointed out that the composite films had good wear resistance. The SEM, EDS and three-dimensional reconstruction were used to analyze the abrasion mark in detail. The results show that the wear behavior of the composite film is mainly adhesive wear and wear oxidation. The doping of ZrB2 particles can improve the wear of the matrix sample. The corrosion resistance of the composites was also estimated by electrochemical methods and the electrochemical parameters are analyzed in detail. The properties of the composite films can be significantly enhanced by the disperse phase strengthening effect brought by ZrB2.
      原文链接:
    • NSTL

    Electrostatic and tribological properties of hydrogenated diamond-like carbon on anodic aluminium oxide

    Yamamoto S.Nonaka T.
    5页
    查看更多>>摘要：© 2022 Elsevier B.V.The electrostatic and tribological properties of three types of anodic aluminium oxide (alumite) and hydrogenated Diamond-Like Carbon (DLC) on alumites were investigated. It was first proven that an ultrathin DLC at 5 nm on an insulative surface exhibits slow discharge. For alumites, clear electrostatic discharge behaviour was not observed in spite of the fact that surface resistance was in the dissipative region of 1010 Ω. Upon coating alumites with a hydrogenated DLC, slow charge and discharge were observed. DLC coatings on alumites significantly improved dielectric strength and hardness due to DLC's intrusion into the porous structure of the alumites. The coefficient of friction on alumites, which stood at 0.9 against Al2O3 and E52100 balls, was much improved to 0.1 with a DLC coating, and so was wear loss and life time.
      原文链接:
    • NSTL

    Theoretical and experimental study of spontaneous adsorption-induced superhydrophobic Cu coating with hierarchical structures and its anti-scaling property

    Peng Y.Li P.Li H.Xin L....
    5页
    查看更多>>摘要：© 2022 Elsevier B.V.Some experimental studies have proven that micro/nano structured coatings achieve superhydrophobicity in air, without low-energy modification. However, it remains an issue how comprehensively explain the reason for changes in wettability. Herein, a hierarchically (nano-submicron-micro) structured Cu coating was fabricated on pipeline steel substrate by one-step electrodeposition. Notably, the superhydrophilic hierarchically structured Cu coating transforms to superhydrophobicity after stored in air for 15 days without chemical modification, with water contact angle of 151° and roll off angle of 3°. Both the microstructure and the chemical composition were characterized to understand the wettability transition mechanism. The fresh hierarchically structured Cu coating exists various defects, with high surface energy, which lead to superhydrophilicity. After the Cu coating stored in air, hydroxylation contributes to hydrocarbons adsorption, resulting in superhydrophobicity. The adsorption kinetic curve model shows that the hierarchical structure promotes hydrocarbon adsorption, which prominently reduces the transition time from superhydrophilicity to superhydrophobicity. The three-level wetting model is constructed to analyze the wetting state when water contacts the Cu coating, which verifies that it is the stable Wenzel-Cassie-Cassie wetting state. Moreover, the superhydrophobic Cu coating maintained anti-scaling property after immersing at 70 °C for 4 h. The anti-scaling behavior and mechanism of the superhydrophobic Cu coating were analyzed by both nucleation and wetting theories. The Cu coating also shows excellent self-cleaning property, water droplet impact resistance, and chemical stability. The superhydrophobicity of the Cu coating also maintained in weak acid and base solutions for 12 min. This study enriches and develops the theory and the technology in the field of wetting, and provides technical support and theoretical basis for the development of superhydrophobicity without low-energy modification.
      原文链接:
    • NSTL

    Synthesis of self-healing NiAl-Al2O3 composite coatings by electrochemical way

    Troncy R.Boccaccini L.Bonnet G.Pedraza F....
    5页
    查看更多>>摘要：© 2022Nickel aluminide diffusion coatings act like an aluminium reservoir to form protective alumina scales at high temperatures. However, interdiffusion phenomena play a critical role in the metallurgical integrity of these coatings. This work explores a new type of self-healing coating for high temperature oxidation applications. Micro-reservoirs consisting of an aluminium-rich intermetallic core (Al3Ni2) and an aluminium oxide shell are embedded in a nickel aluminide matrix (NiAl). This new type of coating has been synthesized by an electrochemical chemical route to trap the micro-reservoirs in an electrodeposited nickel matrix followed by aluminization via a slurry route. Under high temperature oxidation conditions, the micro-reservoirs allow to form a diffusion barrier and to release Al into the coating matrix. These two simultaneous phenomena make it possible to maintain a sufficient amount of aluminium and ensure the unique formation of α-alumina at the surface of the coatings, hence to possibly increase the lifespan of the aluminium diffusion coatings.
      原文链接:
    • NSTL

    Experimental and numerical studies of fatigue behavior of Ti6Al4V alloy treated by laser shock peening

    Zhang H.Cai Z.Guo W.Zhang Y....
    5页
    查看更多>>摘要：© 2022 Elsevier B.V.Laser shock peening (LSP) is applied as the laser surface treatment technology to improve the fatigue resistance of aircraft parts with complex geometric features. In this paper, the effects of laser energy inputs on residual stresses and fatigue properties for hole-structured specimens of Ti6Al4V alloy treated by LSP are studied. Changes of residual stress distributions, fatigue behaviors and fracture morphologies are analyzed with different laser-induced shock pressures. The results show the fatigue life is prolonged by 137% compared with the untreated specimens due to the introduction of compressive residual stresses. The sectional observations of fatigue fracture morphology show the inwards movement of fatigue crack initiation positions and the complexity of fracture cracks after LSP treatment. The simulation results confirm that the fatigue life with different laser energy inputs depends strongly on the three-dimensional stress distribution around the hole. Among them, high surface compressive stresses and deep stress affected layers play a decisive role in improving fatigue life. The results in this study broaden the knowledge of fatigue behavior and explore engineering potentials of improved fatigue life for complex industrial specimens.
      原文链接:
    • NSTL

    Temperature-dependent residual stress and thermal stability studies of multilayer HF-CVD diamond coatings on RB-SiC

    Bhattacharya S.S.Das R.Rao M.S.R.Prabhakaran G.S....
    5页
    查看更多>>摘要：© 2022Structurally graded multilayer (ML) diamond coatings were deposited on reaction bonded silicon carbide (RB-SiC) using a hot filament chemical vapour deposition (HF-CVD) system via two different routes: a continuous process (C-ML) and a three-step intermittent process (Ix-ML, x being the number of steps). In this study, the temperature-dependent residual stresses and thermal stabilities of the C-ML and Ix-ML coatings after annealing at 100° intervals from 100 °C–800 °C were investigated. Scanning electron microscopy, 2D/3D Raman mapping, cluster analysis, and sp2/sp3 ratio computations were carried out at all stages and the results were compared. The residual stresses of the as-deposited coatings, I1-ML, I2-ML, I3-ML, and C-ML, were compressive with values of −1.09 GPa, −0.90 GPa, −0.62 GPa and −1.35 GPa, respectively, which progressively shifted to the tensile regime on annealing and exhibited values of 0.50 GPa, 0.50 GPa, 0.61 GPa and 1.75 GPa respectively, after annealing at 700 °C. The sp2/sp3 ratios of the C-ML and I3-ML coatings dropped from 0.94% to 0.54% and 1.07% to 0.54%, respectively, as the annealing temperature increased from 100 °C to 700 °C. All coatings were completely oxidised at 800 °C except I3-ML, where patches of the original coating persisted even after annealing at 800 °C.
      原文链接:
    • NSTL

    Numerical simulation and parameter sensitivity analysis of multi-particle deposition behavior in HVAF spraying

    Gao X.Li C.Han X.Chen X....
    5页
    查看更多>>摘要：© 2022 Elsevier B.V.Particle deposition behavior is critical to improve coating quality. Based on the Coupled Eulerian and Lagrangian (CEL) method, a three-dimensional multi-particle random deposition model was established, and grain inhomogeneity was introduced into the TC18 substrate. A polycrystalline model of the microstructure for the sprayed substrate was established by the Voronoi method. The evolution of the temperature, strain and stress fields during particle deposition was revealed, and the formation mechanism of pore defects was also analyzed. The results show that the overall strain of small particles is large, the core strain of large particles is small, and the edge strain is significant. The stress value near the large particles in the coating is large, while the stress at the edge of the coating is relatively small. The stress distribution of the TC18 substrate is similar to the uneven random geometric distribution of grains. On this basis, the response surface model of coating characteristics was established, the influence of process parameters on coating characteristics was analyzed, and the sensitivity of process parameters is determined. This research can provide a basis and guidance for engineering applications in related fields.
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    • NSTL

    Mechanical and tribological properties of Ti-Al-Ta-N/TiAl and Ti-Al-Ta-N/Ta multilayer coatings deposited by DC magnetron sputtering

    Shugurov A.R.Kuzminov E.D.
    5页
    查看更多>>摘要：© 2022 Elsevier B.V.The mechanical properties, microstructure, adhesion and wear behavior of a Ti0.41Al0.48Ta0.11N monolithic coating and Ti0.41Al0.48Ta0.11N/Ti0.45Al0.55 and Ti0.41Al0.48Ta0.11N/Ta multilayers were investigated. The coatings were deposited on titanium substrates by reactive DC magnetron co-sputtering. The hardness and reduced elastic modulus of the coatings were determined by nanoindentation. The multilayer coatings were found to exhibit the lower mechanical characteristics than those of the monolithic coating due to the contribution of the softer metal interlayers to their measured values. Adhesion evaluation was performed by scratch testing. The Ti0.41Al0.48Ta0.11N/Ti0.45Al0.55 multilayer was characterized by stronger adhesion to the titanium substrate than the monolithic coating, whereas the Ti0.41Al0.48Ta0.11N/Ta multilayer exhibited poorer adhesion. In contrast, both the multilayers showed improved wear resistance compared with the monolithic coating. The best wear performance was demonstrated by the Ti0.41Al0.48Ta0.11N/Ti0.45Al0.55 multilayer that was attributed to stronger bonding between the layers as well as the lower hardness of the Ti0.45Al0.55 layers, which allowed for the accommodation of a larger amount of deformation via their plastic flow.
      原文链接:
    • NSTL

    In-situ formation, structural transformation and mechanical properties Cr–N coatings prepared by MPCVD

    Xia Y.Peng J.Shen Q.Wang C....
    9页
    查看更多>>摘要：© 2022 Elsevier B.V.This study innovatively employed the microwave plasma chemical vapor deposition (MPCVD) technique to fabricate Cr–N coatings. The influence of preparation temperature on chemical composition, crystalline phase, morphology, and mechanical properties of the coatings were analyzed systematically. The increase of preparation temperature resulted in the structural transformation of the Cr–N coatings from the duplex of Cr2N/CrN to the single-phased Cr2N. The coatings with dense and flat surface were obtained at ≤800 °C; however, the decomposition of CrN to Cr2N and N2 led to the formation of pores at ≥850 °C and consequently an increase in friction coefficient and wear. The hardness and elastic modulus increased with increasing temperature because of the structural evolution of the Cr–N coating and phase transformation. 800 °C was the optimal preparation temperature as the coating exhibited a dense surface and possessed the best overall mechanical properties.
      原文链接:
    • NSTL