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Surface & Coatings Technology
Elsevier Sequoia
Surface & Coatings Technology

Elsevier Sequoia

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Surface & Coatings Technology/Journal Surface & Coatings TechnologySCIISTP
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    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

    Pre-treatment of Selective Laser Melting (SLM) surfaces for thermal spray coating

    Lusvarghi L.Sassatelli P.Franci R.Pulci G....
    5页
    查看更多>>摘要：© 2022 Elsevier B.V.In this work, we investigated the deposition of thermal spray coatings onto additively manufactured parts obtained by Selective Laser Melting (SLM). SLM is indeed replacing conventional subtractive machining to produce diverse industrial parts; hence, it will become increasingly frequent to apply thermal spray coatings onto SLM surfaces. Whilst grit-blasting is the most widely accepted process to prepare a conventionally machined part for a thermal spray coating, the unique surface texture of SLM surfaces might open new possibilities. As a case study, we chose High Velocity Oxygen-Fuel (HVOF) spraying of WC-10%Co4%Cr onto AISI 316 L SLM surfaces in three different conditions: “as built”, pickled, or grit-blasted. We also examined SLM surfaces grown along different directions: parallel, perpendicular, or inclined with respect to the build platform. The references were a machined and grit-blasted SLM part, and a grit-blasted stainless steel bulk. Dense coatings were obtained on every surface regardless of its roughness and pre-treatment. Electrochemical corrosion testing confirmed the low porosity of the layers. Tensile adhesion/cohesion strength was >70 MPa on both SLM and reference surfaces, but the presence of an oxide scale on as-built surfaces degraded the adhesion strength to some extent. Although TEM analysis showed occasional evidence of diffusion bonding between the coating and the oxide scale, cyclic impact tests revealed that the scale itself broke. Particularly strong adhesion was achieved with pickled surfaces; indeed, failure was only cohesive (i.e. within the coating) in both tensile and impact tests. In addition to mechanical interlocking to the rough surface profile, TEM showed widespread diffusion bonding to the clean metal. An SLM part might therefore need chemical activation but no subtractive machining before application of a thermal spray coating. The coating also exerts a levelling action toward the SLM surface, i.e. the coated surface is smoother than the as built one.
      原文链接:
    • NSTL

    Revealing the deformation mechanisms of the heterogeneous structured CrMnFeCoNi high entropy alloy with ameliorated mechanical and corrosion resistance properties

    Li S.Li Y.Zou Y.
    5页
    查看更多>>摘要：© 2022Developing high entropy alloy (HEA) with both high strength and ductility is a longstanding challenge as potential structural materials. The strength and ductility trade-off can achieve via tailoring heterogeneous structures. Herein, a gradient structure with grain size variation from surface to center was successfully introduced into the CrMnFeCoNi HEA by ultrasonic nanocrystal surface modification (UNSM) process. More importantly, the deformation mechanisms and strengthening mechanisms of the heterogeneous structured CrMnFeCoNi HEA during tension were also investigated. Experimental results demonstrated that the heterogeneous structured CrMnFeCoNi HEA shows excellent strength and ductility combination properties ascribed to the grain refinement strengthening, dislocation density strengthening, and twinning strengthening. Besides, the corrosion resistance properties are also simultaneously improved, resulting from the low surface roughness, small grain size, and large compressive residual stress value. During tensile deformation process, the deformation mode is the dislocation slip at low strain and the slip system of the alloy is mainly {111}〈110〉. With the increase of deformation amount, twin crossing occurs, and grain size gradually decreases. The deformation mode changes from dislocation slip to twinning at high strain. In conclusion, the UNSM process ameliorates the comprehensive mechanical and corrosion resistance properties of CrMnFeCoNi HEA.
      原文链接:
    • NSTL

    Preparation of Ni-P-Ti3C2Tx-Ce composite coating with enhanced wear resistance and electrochemical corrosion behavior on the surface of low manganese steel

    Huang S.Li J.Zhang X.Han P....
    5页
    查看更多>>摘要：© 2022 Elsevier B.V.Ti3C2Tx, as a promising material, has attracted extensive attention due to its excellent properties. At the same time, Ce3+ is also a very effective corrosion inhibitor, which can play huge roles in anticorrosion. In this study, Ti3C2Tx-Ce powders were synthesized successfully by doping Ce3+ into Ti3C2Tx powders through a simple reaction. In addition, the Ni-P-Ti3C2Tx-Ce composite coating was synthesized by adding Ti3C2Tx-Ce particles into the Ni-P coating via an electrodeposition technique. Meanwhile, wear resistance performance studies have shown the coefficient of friction (COF) of the Ni-P-Ti3C2Tx-Ce composite coating is about 0.10, which is much lower than that of the Ni-P coating. The wear amount of Ni-P-Ti3C2Tx-Ce composite coating is only about 0.60 mg after 5 min of dry grinding under a load of 5 N and a radius of 5 mm. The microhardness of this composite coating has also been greatly improved, up to 3200 kg·mm−2. Furthermore, electrochemical corrosion behavior studies have shown the corrosion resistance (Rp) of the Ni-P-Ti3C2Tx-Ce composite coating is 120 times higher than that of the Ni-P coating, and 19 times higher than that of the Ni-P-Ti3C2Tx composite coating. The corrosion current of Ni-P-Ti3C2Tx-Ce composite coating is 3 orders of magnitude lower than that of Ni-P coating. Therefore, Ni-P-Ti3C2Tx-Ce coating is a promising material for device surface protection.
      原文链接:
    • NSTL

    Effect of carbonaceous reinforcements on anticorrosive and magnetic properties of Ni-Cu based composite coatings prepared by pulsed electrodeposition

    Firdouz Z.Mondal K.Balani K.Tripathi P....
    5页
    查看更多>>摘要：© 2022 Elsevier B.V.Magnetic and anticorrosive properties of Ni-Cu alloy-based composite coatings prepared by pulsed electrodeposition reinforced with CNT (Ni-Cu-CNT), graphene (Ni-Cu-G), and diamond (Ni-Cu-D) have been assessed in the current work. The corrosion behavior of the composite coatings was evaluated in a 3.5% NaCl corrosive medium. Linear polarization test performed within ±10 mV with respect to open circuit potential (OCP) unveiled that graphene added coatings exhibited maximum polarization resistance (~13.1 kΩcm2) followed by the Ni-Cu-D (~9.1 kΩcm2), the Ni-Cu-CNT (~8.3 kΩcm2), and the Ni-Cu with a minimum resistance of ~4.2 kΩcm2. Electrochemical impedance spectroscopy tests performed with a signal perturbation of ±10 mV with respect to OCP and frequency sweep from 105 Hz to 10−2 Hz elicited maximum film resistance of ~32 kΩ cm2 for the Ni-Cu-G coating, which could be attributed to the high area to volume ratio, α ~134/m, of graphene nanoflakes inducing strong particle-matrix interaction and to the formation of micro galvanic cell between the graphene particles and the Ni-Cu matrix where the surface was covered predominantly with graphene, eventually lowering the corrosion rate to 5.91 MPY. For Ni-Cu-D coating, the uniform dispersion of diamond particles prohibits localized corrosion. In contrast, agglomeration of CNTs in Ni-Cu-CNT causes ~50% reduction in corrosion resistance compared to diamond reinforced coating. However, corrosion resistance of CNT grafted coating was around 2.5 times higher than Ni-Cu (~4.2 kΩcm2), which can be imputed to the filling of the pores, cracks, and crevices by CNT fibers. The hysteresis loops of Ni-Cu composite coatings traced by a vibrating sample magnetometer indicated that CNT incorporation enhanced the magnetic saturation to ~1.89 Am2/kg from ~0.84 Am2/kg (Ni-Cu) and maximum coercivity of ~110 Oe (~78.91 Oe for Ni-Cu). However, graphene and diamond addition has negligible effect on the magnetic properties of the coated systems. The enhanced anticorrosive and magnetic properties of proposed coating designs consisting of Ni-Cu matrix with carbonaceous reinforcements impart multifunctionality to the system. The marine industry can successfully adopt the proposed coating systems to protect propellers shafts, ship hulls, and specialty sensors.
      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

    Fretting fatigue experiment and simulation of WC-12Co coating taking into account the wear effects

    Wang X.X.Ping X.C.Zeng X.Wang R.J....
    5页
    查看更多>>摘要：© 2022 Elsevier B.V.WC-12Co coating can be used to improve the wear resistance of mechanical connectors, but due to the fretting behavior between the contact interfaces during service, the problem of fretting fatigue cannot be ignored. Through the fretting fatigue experiment and simulation study of the WC-12Co coating, the fretting fatigue mechanism of the coating was investigated under the premise of considering the competitive or coupling relationship between fretting wear and fretting fatigue. Based on Smith-Watson-Topper (SWT) fatigue damage parameter and Miner-Palmgren (M-P) linear cumulative fatigue damage theory, a prediction model for fretting fatigue crack initiation life of WC-12Co coating was established, and the stress redistribution caused by fretting wear was analyzed by Archard wear theory. The analysis results show that the fretting fatigue cracks of the WC-12Co coating mainly initiate at the edge of the wear pits and gradually extend to the substrate; the increase of external load and friction coefficient will accelerate the fretting fatigue process of WC-12Co coating and reduce its fretting fatigue crack initiation life; the change of fretting fatigue crack initiation life and position of WC-12Co coatings caused by fretting wear depends on the change of contact state between contact interfaces.
      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

    Evaluation of the long-term anticorrosion behavior of (OCP + Ca-P)/MAO coated magnesium in simulated body fluids

    Zhang X.Zhou L.Cui S.-D.Lian J.-B....
    5页
    查看更多>>摘要：© 2022 Elsevier B.V.Magnesium has attracted wide interest as a biodegradable metal implant. However, the weak corrosion resistance restricts its practical applications. A Ca[sbnd]P sealing coating was prepared on the surface of microarc-oxidation coating (MAO)-coated Mg via a liquid-phase deposition. The liquid-phase deposition time affects not only the microstructure and phase composition of Ca[sbnd]P coating, but also the long-term anti-corrosion and biodegradability of the MAO coated Mg. The phase composition of the Ca[sbnd]P coating evolves from octacalcium phosphate (OCP) + Ca-P compound (Mg-containing) to Ca2.86Mg0.14(PO4)2 with increasing deposition temperature. Mg with (OCP + Ca-P compound)/MAO coating exhibits outstanding anti-corrosion property during 60 days of immersion in simulated body fluids. Meanwhile, the OCP + Ca-P compound coating can facilitate the deposition of osteoconductive minerals, i.e., the hydroxyapatite layer, on the OCP coating during immersion in SBF solution. A rational model for the anticorrosion procedure of the Mg with (OCP + Ca-P)/MAO coating in SBF solution for a long-time immersion is proposed.
      原文链接:
    • NSTL

    Very high cycle fretting fatigue of Nimonic 80A modified by laser cladding with Stellite X-40 and In625/20 % WC

    Wang J.Huang Z.Yu C.Han G....
    5页
    查看更多>>摘要：© 2022Nimonic 80A alloy is widely used in rotor blades, guide vane supports and other aeroengine components. It is exposed to harsh fretting wear and high temperature loads, which reduces the fatigue resistance of the components. Laser cladding (LC) technology is utilized to improve structural integrity and fatigue resistance. The aim of the research is to assess the resistance of Nimonic 80A in the very high cycle fretting fatigue (VHCFF) after cladding with Stellite X-40 and In625 + 20 wt% WC. The wear morphology and fracture mechanism of the specimens were studied using scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM). The results show that the crack initiation sites are mainly classified into three types, namely surface initiation, interior initiation, and LC interface initiation. The fretting wear introduces compressive residual stress along the wear depth, as well as the bulk stress, residual stress, and cladding defects all play dominant roles in crack initiation. Especially up to 108 cycles, the glaze oxide layer (GOL) helps to reduce friction coefficient and make the compaction of wear debris easier, inhibiting the crack nucleation. The different distribution of residual stress in on the LC layer and the stronger wear resistance of WC particles lead to the higher fatigue strength and life of the specimen with In625 + 20 wt% WC cladding material compared with the Stellite X-40 ones.
      原文链接:
    • NSTL