The current communication deals with elaboration of electrodeposited graphene oxide (GO)-reinforced copper composite coating with tribomechanical and electrical properties. Graphene oxide, chemically ...reduced graphene oxide (RGO) and thermally reduced graphene oxide (TRGO) with different concentrations (0.1, 0.5 and 1 g/L) were incorporated in the copper matrix. The surface-mechanical and electrical properties of the developed coatings were investigated for possible electrical contacts applications. The deposition process was carried out at a pH value of 1 ± 0.02, which was sufficiently below the isoelectric point of RGO and TRGO to avoid possible agglomeration during deposition. A structural change of the synthesized specimens and the presence of GO in the composite coating were demonstrated from Raman spectra characterization. X-ray photo electron spectroscopy of some specific specimens (RGO, TRGO and Cu-0.5 g/L TRGO) was carried out to study the elemental composition, chemical state and electronic state of the elements present. Improvement of mechanical and electrical properties was clearly evident due to dispersion hardening caused by uniform dispersion of second-phase GOs. Cu–TRGO composite coating shows excellent electrical conductivity as compared to GO- and RGO-reinforced composite coatings due to removal of oxygen-containing groups after thermal reduction process.
This work reports successful development of pure Ni and Ni-MoS2 bulk nano-crystalline electrodeposited coatings and it's mechanical and wear behavior. The crystallite size of the Ni in the Ni-MoS2 ...coatings varies from 31.6 to 146.8 nm at different loading levels of MoS2 (1, 2, 5, 10 and 20 g/l) in the deposition bath. The nanocrystalline Ni in the Ni-MoS2 coatings follow inverse Hall-Petch relation, as the hardness value is observed to decrease with decrease in crystallite size of the Ni below 62.2 nm. The wear mechanism of the electrodeposited pure Ni and Ni-MoS2 electrodeposits has been analyzed using micro-scratch technique with progressive load of 100 to 1000 mN. Moreover, all the Ni-MoS2 coatings display significantly improved wear resistance than the pure Ni electrodeposit due to the higher hardness of the Ni-MoS2 coatings caused by dispersion hardening. Moreover, the wear behavior of the Ni-MoS2 coatings has been correlated with crystal orientation, coating morphology and hardness to establish the possible abrasive wear mechanism.
•Electrodeposited pure Ni and nanocrystalline Ni-MoS2 coatings were synthesized.•The synthesized coatings are pore-free and compact.•Hall-Petch breakdown for the composite coatings was observed.•Ni-MoS2 coatings depict excellent hardness and wear resistance.
This study explores the hydrophobicity of micro and nano-hierarchical structured Cu–10 g/L ZrO2 pulse electrodeposits as a function of different concentrations (0.1, 0.5 and 1 g/L) of cetrimonium ...bromide (CTAB, a cationic surfactant) addition. Beyond 0.1 g/L CTAB loading, the composite coatings display duplex nano-cone morphology. Specifically, 0.5 g/L CTAB loaded coating shows free standing hemispherical morphologies consisting of vertically aligned nano-cone arrays, whereas 1 g/L CTAB loaded coating displays flowery like hierarchical nano-cone morphology. However, 0.1 g/L CTAB addition makes the coating morphology finer as compared to non-CTAB loaded coating with ordered nano-cone morphology. Among all the developed coatings, 0.5 and 1 g/L CTAB loaded coatings display superhydrophobic behavior by mimicking the ‘lotus leaf’ architecture. The entrapped air pockets formed beneath the liquid droplet due to the formation of micro and nanometer-scale topographic features mainly attribute to the transition from hydrophilic Cu substrate to superhydrophobic Cu–ZrO2 hierarchical coating structure. In addition, high surface roughness along with the high value of the ratio between mean profile spacing (Sm) to mean profile width (Wa) facilitates the air entrapment in between the protrusions of the coated structure. Moreover, formation of low surface energy (111) crystal plane with respect to the CTAB loadings can be considered as another reason for the excellent hydrophobic behavior of the obtained Cu–ZrO2 coatings.
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•Surfactant loaded Cu-ZrO2 coatings display excellent hydrophobicity.•The wettability is also strongly related to Ra, Rsk, Sm/Wa, RTC(111)/RTC(200).•Duplex structure of 0.5 and 1 g/L CTAB added coatings satisfied ‘lotus leaf effect’.
The present study describes about both microstructure and crystallographic texture evolution of electrodeposited Nickel (Ni) and Ni-Al composite coatings synthesized at different current densities ...(1, 5, and 8 A/dm2) and its subsequent effect on mechanical and electrical properties. Nucleation and growth of the grains in the coatings are considerably affected by Al incorporation, stress generation, and specific crystal orientation development caused by applied current densities. CSL boundaries of type Ʃ3 are predominantly observed throughout the coatings and higher in case of Ni-Al coatings. Overall best mechanical properties (hardness and wear) of Ni-Al coating prepared at 1A/dm2 is attributed to lowest average grain size, 〈100〉 texture and higher average misorientation. Electrical conductivity of Ni-Al coating prepared with 8A/dm2 is observed as maximum among the composite coatings due to even distribution of grains. Overall, in terms of mechanical and electrical characteristics, Ni-Al coating prepared at 1A/dm2 current density shows optimum properties.
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•Coating substrate's nucleation-growth controlled by amount and distribution of Al.•Grain distribution: finer-inhomogeneous-equiaxed with increasing current density.•Grain size, misorientation, 〈100〉 texture affected mechanical, electrical properties.•Ni-Al coating shows optimum properties at lower current density (1 A/dm2).
The current work elaborates the oxidation behavior of pure Cu coating (copper coating on copper substrate) and reduced graphene oxide (RGO) reinforced copper coating on copper substrate prepared by ...direct current (DC) electro-codeposition. The isothermal oxidation of all the coated specimens was carried out at 0.5, 0.6 and 0.7 of the melting temperature of pure copper for 30 h. Isothermal oxidation plots at 406, 542, and 678 °C temperatures confirmed better oxidation resistance of the composite coatings than that of the pure copper coating. X-ray diffraction (XRD) results of the coatings after oxidation showed the presence of RGO, copper oxide (CuO) and cuprous oxide (Cu2O) along with small Cu peaks. Microstructural analysis revealed that not only the RGO content in the composite matrix but also the structure of the coating matrix greatly influenced the oxidation behavior of the coating. X-ray photo electron spectroscopy (XPS) results of the coatings after oxidation showed improved oxidation resistance of composite coatings as compared to the pure Cu coating.
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•Cu-reduced graphene oxide (RGO) coatings are developed by electro-deposition.•High temperature oxidation resistance of Cu improves with RGO codeposition.•RGO reduces the oxygen diffusion and gives very good oxidation protection.•Oxidation kinetics follows cubic rate law.
The main objective of the present work is to fabricate continuous regime of surface micro-texturing on flat surfaces of a dual phase steel (DPS) and a commercial pure Cu by laser micro-texturing only ...on the araldite mask laid on the specimen followed by electrochemical dissolution. The sharp and blunt conical grids with average base width (maximum distance between two consecutive micro-channels) of 174 and 214.3 μm as well as 42.2 and 54.3 μm of average depth of dissolution were achieved using two steps electrochemical dissolution process in the DPS and Cu specimens, respectively. Solution used for electrochemical dissolution of the DPS was freely aerated 3.5 wt% NaCl, whereas, etchant for Cu consisted of nitric acid, acetic acid and sulfuric acid with deionized water. Different aspects of creating micro-texturing, like masked coating thickness, micro-channel dimension, depth of dissolution and grid patterns were discussed. No change in hardness of the surface as well as absence of cracks before and after micro-texturing suggested negligible variation in the microstructure due to processing. In addition, the two-step preparation of micro-textured surfaces showed considerable hydrophobicity in addition to the considerable increase in surface area.
The present study discusses the formation of surface micro-texture on flat samples of Cu-based and Ni-based alloys by two-step electrochemical dissolution. Prior to the electrochemical dissolution, ...laser marking only on the araldite coating has been carried out for effective dissolution of the selectively exposed metal surfaces along the laser cut regions. After second stage dissolution, the circular truncated conical grids with average base diameter of 210.7 μm for the Cu-based alloy and truncated square pyramid like grids with base width of 203.2 μm for the Ni-based alloy have formed. Similarly, maximum dissolution depths of 61.8 and 39.3 μm for the Cu-based and Ni-based alloys, respectively, could be observed. Moreover, excellent hydrophobicity of the textured Cu-based as well as Ni-based alloys correlating to grid dimensions along with air entrapment beneath the water droplet has been analysed with the help of Wenzel and Cassie-Baxter models. Nano-hardness of the as-received alloys as well as the textured alloy surfaces shows minor variation. Similarly, the micrographs of the flat surfaces of the as-received alloys and cross-sectional microstructure of the textured alloys have also portrayed little difference suggesting negligible heat or stress affected zone after dissolution process. Moreover, the textured surfaces have showed significant increment in surface area: ∼62.7% for the Cu-based alloy and ∼71.4% for the Ni-based alloy as compared to the flat specimens.
•Ordered surface micro-texturing on Cu and Ni-alloys has been developed.•Nano-hardness result confirms no stress/heat affected zones on textured alloys.•WCA of 141.4° (Cu alloy) and 133.4° (Ni alloy) suggest excellent hydrophobicity.•Maximum surface area increment of 62.7% (Cu-alloy) and 71.4% (Ni-alloy) is observed.
In this work, hydrophobic and corrosion behavior of multi-walled carbon nanotube (MWCNT) reinforced Ni-5 g/l MoSe2 composite coatings on Ni substrate, synthesized by versatile single pot ...electro-codeposition process from a solution containing 0.1, 0.5 and 1 g/l of CNT, were compared with pure Ni coating as well as Ni-5 g/l MoSe2 coating without CNT. All the composite coatings showed excellent hydrophobicity as compared to the pure Ni coating due to the rough surface along with codeposition of low surface energy materials, such as MoSe2 and MWCNT, in the coating matrix. All the coatings showed improved anti-corrosion behavior as compared to the Ni substrate, and the coating with MoSe2 and MWCNT further improved the corrosion resistance. Maximum corrosion resistance of the 0.1 g/l MWCNT reinforced Ni-5 g/l MoSe2 coating among all the coatings could be attributed to the preferred atomically dense (111) plane, lowest lattice strain value, super-hydrophobic surface and higher amount of MWCNT codeposition.
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•Codeposition of MoSe2 and MWCNT facilitates compactness of the coating.•Excellent hydrophobicity for the Ni-MoSe2-MWCNTcoatings is observed.•Electrochemical activity influenced by crystal planes, strain, and hydrophobicity.•0.1 g/l MWCNT added Ni-5 g/l MoSe2 coating shows best corrosion efficiency.
The present work investigates correlation between the structural and tribological behavior of pure Ni coating and Ni-WSe2 composite coatings at different WSe2 loading level (0, 0.1, 0.2, 0.5, 1 and ...2 g/l). The developed coatings were characterized by X-ray diffraction technique (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS) for phase, structure and compositional verifications, respectively. Structural and phase evolution of the coatings were correlated with roughness, microhardness and wear behavior. Characterization confirmed that beyond 0.5 g/l WSe2 content in the electrolyte, the composite coatings turned brittle and non-uniform with high surface roughness. The maximum hardness of 665 HV was observed in case of Ni-0.5 g/l WSe2 coating, whereas, the lowest average coefficient of friction of 0.068 was found in Ni-1 g/l WSe2 followed by 0.07 for Ni-0.5 g/l WSe2 coating. It was observed that Ni-0.5 g/l WSe2 coating possessed optimum mechanical properties and wear resistance.
•Electrodeposited Ni-WSe2 coating with varying WSe2 contents has been developed.•WSe2 content and RTC(111)/RTC(200) greatly affected hardness and wear result.•Ni-0.5 g/l WSe2 composite coating showed optimum properties.•WSe2 can be an excellent reinforcement for improving wear property.
Cu-ZrO2 composite coatings were prepared by pulsed electro-codeposition process with 5kHz pulse frequency from ZrO2 dispersed cetyl trimethyl ammonium bromide (CTAB) added copper sulfate bath on a ...copper substrate to study the influences of CTAB concentration (0.1, 0.5 and 1.0g/l) on structural, mechanical and electrical characteristics of the deposits. Coatings exhibit uniformly dispersed ZrO2 in Cu matrix which becomes finer at intermediate CTAB content. 0.5g/l CTAB assisted coating shows duplex structure having very high hardness (3.23GPa) followed by 0.1g/l CTAB assisted coating (2.91GPa) due to presence of ZrO2, nano-cone structured matrix with favorable crystallographic texture. Surface profile result confirmed high surface roughness of 5.6μm for 0.5g/l CTAB assisted coating due to duplex matrix formation and least roughness was observed as 0.31μm for Cu-ZrO2 composite coating without CTAB addition. Tribological behavior was found similar to hardness results. It was also observed that CTAB addition marginally decreases electrical conductivity of the coatings.
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•Electrodeposited CTAB assisted Cu-ZrO2 composite coatings show nano-cone arrays.•CTAB addition enhances surface mechanical properties.•Improved hardness/wear due to ZrO2, nano-cone matrix with specific orientation•Minor decrease in electrical conductivity for ZrO2 and fine structure
