Ni-based Coatings Research Articles

Effect of a pulsed magnetic field on the tribological properties of amorphous/nanocrystalline composite coatings by supersonic plasma spraying

Pulsed magnetic fields can enhance ferromagnetic and paramagnetic materials by enhancing their stress structure, domain variation, phase structure distribution and grain size of both solid and molten metals. Thus, Ni-based coatings were prepared by pulsed magnetic field-assisted supersonic plasma spraying under a strong magnetic field of 5 T, based on the characteristics of a pulsed magnetic field and combined with the advantages of supersonic plasma spraying technology. According to the results, the porosity of the coatings prepared using this approach decreased, the magnetic domains appeared as sheet domains and showed a sinusoidal distribution, numerous amorphous/nanocrystalline structures appeared, enhanced grain orientation and the coatings had good tribological properties. This study offers a new perspective on the design of high strength metal base coatings for various applications.

ELECTRODEPOSITION BASED DEVELOPMENT OF Ni–TiN–AlN AND Ni–SiC–Cr COMPOSITE COATINGS FOR TUNGSTEN CARBIDE CUTTING TOOLS

Metal-based functionally graded coatings have proven effectiveness in improving anti-wear properties and surface integrity of the substrates. The use of electrodeposition coating technique, considering the economics and versatility associated with this method, is a preferred technique of depositing metal-based composite coatings. Further, Ni-based composite coatings are proven for anti-wear applications, and addition of various reinforcement for developing functional coatings need to be evaluated for different applications. This study describes the development, analysis, and performance evaluation of Ni–TiN–AlN and Ni–SiC–Cr electrodeposited composite coatings on tungsten carbide (WC) tool substrates, to impart improved anti-wear properties during machining. The composite coatings were deposited and optimized for current density values of the electrodeposition process, which was identified as the most significant parameter in both the cases. The coatings were characterized using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) for microstructural analysis. The results were further analyzed for tribological behavior through microhardness and adhesion strength tests of the deposited coatings, which are significant properties imitating anti-wear characteristics of the substrate. A significant increase of 47% and 36% in microhardness was obtained for Ni–SiC–Cr coated specimen and Ni–TiN–AlN coated specimen, respectively, compared to the uncoated WC substrates, accompanied with a good adhesion strength in both the cases. The microstructural analysis in both the cases revealed an increase in the deposited coating constituents with increasing current density, leading to a denser coating deposition up to the saturation point, and then beginning of coating delamination due to over-saturation with further increase in current density.

Study on coating morphology, property, and characteristics of in situ synthesis VC-reinforced Ni-based coatings by laser cladding

Study on coating morphology, property, and characteristics of in situ synthesis VC-reinforced Ni-based coatings by laser cladding

Effect of Ni/MoS2 Addition on Microstructure and Properties of Supersonic Plasma-Sprayed Ni-Based Composite Coatings

Abnormal tool wear is a significant problem encountered in machining. MoS2 has the function of friction reduction; thus, to mitigate friction, two Ni-based coatings, Ni60 and Ni60 + 15 wt.% Ni/MoS2, were obtained on tungsten steel using supersonic plasma technology. The microstructure, phase structure, microhardness, fatigue properties, and friction and wear properties of the two coatings were characterized. The results show that the two plasma-sprayed Ni-based coatings have desirable structures. The addition of Ni-coated MoS2 can effectively improve the hardness of the coatings, with values reaching as high as 735 HV. The speed of rotation of the friction ball was set as 200 r/min, and the cutting force was 201.6 N. The fatigue performance as well as the friction and wear performance of the coating are simulated using ANSYS. The fatigue performance is improved by 12.6 % after adding 15 wt.% Ni/MoS2, and the friction system of the coating becomes stable after 25 min of contact. The addition of 15 wt.% Ni/MoS2 can effectively improve the performance of the tool material.

Preparation of high wear resistance nickel based WC coating by carefully adjusting interface structure

In recent years, many scholars have paid attention to wear-resistant coatings for shield machine cutterheads due to their very high consumption rates. Among these coatings, nickel-based tungsten carbide (Ni-based WC) is one of the best, showing both corrosion resistance and wear resistance. However, to further improve the wear resistance of such coatings, there are still numerous issues that need to be resolved. Herein, a new method, distinct from conventional methods, is presented. Specifically, the brittle phase W2C is not widely regarded as the main wear-resistant phase, but we were surprised to find that careful adjustment of its rigid structure can yield satisfactory results. Experimental results and first-principles simulations have indicated that the friction coefficient and weight loss of a coating with a suitable distribution of W2C are only half of those of a traditional Ni-based WC coating (about five times higher than those of the substrate), which can mainly be attributed to the excellent thermal expansion coefficient and hardness of the W2C phase. As we expected, the surface morphology of the material after wear revealed that the suitable W2C layer has a well-defined friction morphology. We hope to provide new ideas for the study of Ni-based WC coatings in shield machine cutterheads.

Mechanical Reinforcement of AISI1018 Steel by a Ni-based Self-fluxing Alloy Coating Applied by Plasma Transferred Arc (PTA)

Mechanical Reinforcement of AISI1018 Steel by a Ni-based Self-fluxing Alloy Coating Applied by Plasma Transferred Arc (PTA)

Microstructure and Wear Property of Graphene Nanoplatelets Reinforced Nickel-Based Composite Coating by Laser Cladding

Nickel-based composite coatings containing graphene nanoplatelets (GNPs) were prepared on Q235 steel using laser cladding. In order to retain the multilayer GNPs in the composite coatings after laser cladding, NiGNPs were prepared by electroless nickel plating on GNPs as the additive phase. All the coatings contain γ-(Ni, Fe), Cr23C6, Cr7C3, Fe3C and WC phases, and multilayer GNPs were retained successfully in the composite coatings. With the addition of GNPs, the microstructure of the coatings was obviously refined and the content of Cr-C compounds were increased along with its changed morphology. The mean microhardness of the Ni-based composite coatings containing GNPs was significantly improved compared to that of Ni45 coating, and the maximum microhardness was 745.06 when 20% NiGNPs was added. The results indicated that, due to the refinement and lubricating effects of GNPs, the friction coefficients of composite coatings were reduced and the wear resistance was improved compared to Ni45 coating.

Evaluation of residual stress in thick metallic coatings using the combination of hole drilling and micro-indentation methods

Plasma spraying is commonly used to deposit thick metallic coatings. The high deposition temperature and complex interaction of the process parameters result in tensile residual stresses in thick metallic layers. Tensile residual stresses are widely known to affect the integrity of metallic coatings. The present study uses a combination of hole drilling and micro-indentation techniques to evaluate the residual stress developed in Ni-based metallic coatings deposited on stainless steel substrate using a direct current plasma spray torch. The metallic coating samples are first characterized by microscopy, surface roughness measurement, micro-indentation, and scratch tests before through-thickness residual strain measurement via the incremental hole-drilling method. The residual stress in the metallic coating layers is evaluated from the incremental strain measurements and micro-indentation curves. The studies show that the residual stress can be reliably predicted using the combination of hole drilling and micro-indentation measurements. It is found that tensile residual stresses are developed across the depth of both NiCrAl and Ni–20Al coatings. The variation of the tensile residual stresses across the depth is nonlinear and almost equibiaxial. The residual stress strongly influences the adhesion strength of the thick metallic coating layers.

Corrosion Performance of HVOF-deposited Ni-based Coatings in Simulated Biomass Fired Boiler Environment at 700 °C

Corrosion Performance of HVOF-deposited Ni-based Coatings in Simulated Biomass Fired Boiler Environment at 700 °C

Birleşik PV-alkali elektroliz hidrojen üretim sisteminin enerji depolama performansı ve kullanım potansiyelinin araştırılması

Hydrogen fuel has the potential to reduce CO2 emissions significantly. In this study, PV-alkaline electrolysis cell was combined and during day time it was harvested energy. Some of the deposited energy was used on-grid alkaline electrolysis cell and hydrogen was produced also was stored. In the electrolysis system, Ni-based coatings were operated on steel mesh with the help of the electrodeposition method. It was used re-cycled steel mesh substrates in order to decrease operational costs and also in order to encourage metal-cycling in our country. The relevancy of cathodes was investigated using bulk electrolysis. The characterization was achieved via scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX). Results define both effects of "lab-made cathodes performance comparison" and "the trend of PV panel under different climate and weather conditions". This system reflects the real-time measurements for Adana, Sarıcam region of Turkey.

Failure Analysis of a Chromium Plating Layer on a Piston Rod Surface and the Study of Ni-Based Composite Coating with Nb Addition by Laser Cladding

The failure of a chromium plating layer on the surface of a piston rod was analyzed, and an Ni-based alloy mixed with a niobium (Nb) composite coating was investigated by means of stereomicroscopy, metallographic microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Vickers hardness testing, and wear testing. The results show that penetrating cracks were present in the chromium layer. Subsequently, the corrosion intensified, resulting in the bubbling, cracking, and peeling of the chromium layer. The cladding layer presented a structure morphology of planar crystalline at the bottom, dendritic at the middle, and equiaxial crystalline at the top. The solidification parameters, which were derived from simulation results, confirmed that the ratios between temperature gradient (G) and solidification speed (S) decreased, and the values of the cooling speeds increased from the bottom to the top of the cladding layer. With an increase in Nb content, the structure became gradually refined and uniformly dense. The cladding layer of the Ni-based alloy mixed with Nb was mainly composed of γ-Ni, Cr23C6, Cr7C3, NbC, and Ni3Nb. NbC could be formed in situ and presented itself in four forms: particles, dendrites, polyhedrals, and networks. The microhardness of the coating with 15% added Nb was enhanced to 400 HV0.2, and the wear resistance thereof was 11.14 times higher than the substrate. After the 15% Nb coating had aged for 16 h, the diffraction peak intensities of Cr23C6 and Cr7C3 significantly increased, and the volume fraction of granular NbC increased from 1.67% to 2.54%. The microhardness was enhanced to 580 HV0.2, and the wear resistance thereof was better than that of the chromium plating layer.

Effect of TiC content on the microstructure and wear performance of in situ synthesized Ni-based composite coatings by laser direct energy deposition

To reveal the effect of content and size of in situ synthesized TiC on phase compositions, microstructure, defects, and mechanical properties of matrix composites in detail, a series of Ni-based composite coatings were fabricated by direct energy deposition. The titanium (Ti) + Ni-coated graphite (C) contents in composite powder are 5, 10, 20, 30, 40, and 50 wt%, respectively. With the increase of Ti and C elements, the phases firstly change from γ–Ni, [Fe–Ni] solid solution, CrB, Cr7C3 to [Fe–Ni] solid solution, CrB, Cr7C3, TiNi2 TiC, TiB2, and finally to TiNi, Cr3C2, Fe2Ti, TiC, TiB2 under the competitive interaction between solute concentration and Gibbs free energy. The volume fraction and relative diameter of the TiC reinforcements are increased gradually to 28.06 % and 2.866 μm, respectively. The dispersed TiC particles are found at the grain boundary and refine the grains. The microhardness is increased from 608.41 ± 6.25 HV0.3 to 1075.11 ± 27.94 HV0.3 due to the combined effect of fine-grain strengthening, solid solution strengthening, and the second phase strengthening. The volume loss was significantly reduced when the relative diameter of TiC is larger than 2.2 μm. Moreover, the wear mechanism was transformed from adhesive wear to abrasive wear and ultimately to fatigue wear. In addition, the transverse and longitudinal cracks were also observed, limiting the application of the fabricated coatings.

Microsrtructural and Mechanical Characterization of HVOF-Sprayed Ni-Based Alloy Coating

The various engineering components works under aggressive environments include the furnace parts, sliding parts in lathe machine and exhaust manifolds. Cast iron is used in these applications and important intention of this research work is to study on enhance the useful period of life.HVOF (High Velocity Oxy-fuel) sprayed Alloy-718coatings on cast iron were analysed. Coatings were characterised by field emission scanning electron microscopy (FE-SEM), Optical microscope (OM) and X-ray diffraction for its microstructural analysis. Energy dispersive spectroscopy (EDS) of the bare and coated samples was used to confirm the elemental details of the powder and the coating. Porosity measurements were taken and showed the 1.6% for Alloy-718 coating. Microhardness investigation was conducted for the Alloy-718 coating, and it was resulted as 560±20 HV. The bare material has hardness of 225±10, and there is a substantial difference of hardness found as 2.5 times higher. The fracture toughness was found to be 4.0 MPa.m1/2.

Parameter-dependent tribological properties of sinusoidal-textured plasma-sprayed coatings

Texture parameter was an important factor affecting tribological property. In this work, the friction experiments and orthogonal analysis method were combined to investigate the effects of texture parameters on the tribological properties of sinusoidal-textured Ni-based MoS2 coatings under dry conditions. Results showed that only the texture area ratio, width–depth ratio, and angular velocity have significant effects on the tribological properties, and the influence order was as follows: area ratio > angular velocity > width–depth ratio. Good tribological properties could be obtained when the texture area ratio was 9–10%, the angular velocity was 6 rad/s, the width–depth ratio was 0.67–1.36, the amplitude was 0.1 mm, and the relative motion angle was 90°.

Influence of the Cu content on the electrochemical corrosion performances of Ni60 coating

The effect of element Cu on microstructures and corrosion behavior of the directional structure Ni-based coatings were investigated experimentally. The element Cu enhanced the orientation growth of the coating microstructures, and the coating of Ni60/5 %Cu exhibited the highest corrosion potential (−0.236 V) and the smallest current density (1.238 ×10-6A/cm2). The corrosion resistance of the coating declined with increased Cu content, when the content of Cu reached 20 %, the corrosion potential and current density of the coating dropped to − 0.380 V and 2.100 × 10-6A/cm2, respectively, but they were still better than that of the coating without Cu element, which were − 0.395 V and 2.858 × 10-5A/cm2, respectively.

Effect of CeO2 on Microstructure and Wear Property of Laser Cladding Ni-Based Coatings Fabricated on 35CrMoV Steel

Effect of CeO2 on Microstructure and Wear Property of Laser Cladding Ni-Based Coatings Fabricated on 35CrMoV Steel

An Investigation of the Surface Quality and Corrosion Resistance of Laser Remelted and Extreme High-Speed Laser Cladded Ni-based Alloy Coating

An Investigation of the Surface Quality and Corrosion Resistance of Laser Remelted and Extreme High-Speed Laser Cladded Ni-based Alloy Coating

Effect of Heat-Treatment Temperature on the Tribological Properties of WC-12Co-Reinforced Ni-Based Coating

WC-12Co-reinforced Ni-based coatings were fabricated on Inconel 718 substrates using a high-velocity air-fuel (HVAF) technique. The as-fabricated coatings were heat-treated at a temperature of 970 °C, 1000 °C, 1030 °C, or 1070 °C. The microstructure, mechanical properties, and tribological behaviors of the heat-treated coatings were investigated systematically. The results showed that the heat treatment could reduce the porosity of the coating and promote the metallurgical bonding of the interface between the coating and the substrate. As the heat treatment temperature increased from 970 °C to 1000 °C, the hardness and toughness of the coating increased gradually. After being heat-treated at 1000 °C, the coating possessed the best comprehensive mechanical properties and the best tribological properties at both room temperature and 580 °C. The wear rates of the as-fabricated coatings were 2.63 × 10−6 mm3 N−1 m−1 at room temperature and 3.96 × 10−5 mm3 N−1 m−1 at 580 °C, respectively. Also, the wear mechanisms were fatigue wear as well as abrasive wear accompanied by mild adhesive wear, respectively. However, the wear rates of the coating heat-treated at 1000 °C were 1.04 × 10−6 mm3 N−1 m−1 at room temperature and 3.87 × 10−5 mm3 N−1 m−1 at 580 °C, respectively. The wear mechanisms of the heat-treated coatings at room temperature were mainly fatigue wear and abrasive wear, while the wear mechanisms at 580 °C were mainly abrasive wear accompanied by mild adhesive wear. With the increase of heat treatment temperature above 1000 °C, the mechanical properties and tribological properties of the coating deteriorated gradually.

Process optimization, microstructure and microhardness of coaxial laser cladding TiC reinforced Ni-based composite coatings

Since the precursors for coaxial laser cladding (LC) can be easily customized, less waste, and flexibly applied to the surface of complex parts, LC is a practical and promising approach to fabricate metal matrix composite (MMC) coatings for surface modification or repair compared with selective laser melting, preset powder cladding, gas tungsten arc welding. The precursors for LC MMC coatings are composed of an optimized single alloy powder, hard particles or related elements. However, the process for LC MMC coatings is the same as that for single alloy powder. Since the added materials usually affect the quality of the laser beam, the flow characteristics and the solidification process of the melt pool, the process parameters for LC MMC coatings are often not optimal. Therefore, the coarse TiC particles were firstly added to the commercial Ni45 powder, and the Taguchi method and empirical statistical model are employed to optimize process parameters for LC MMC coatings. A reliable processing map for customized precursors was obtained. Finally, the single-layer multi-track TiC-reinforced MMC coatings were fabricated to verify the correctness of mathematical models. The suitable process parameters combination for LC Ni-based MMC coatings are laser powder of 380 W, scanning speed of 5 mm/s, and powder feed rate of 243.7 mg/s. Moreover, the microhardness of the optimized MMC coating is about 520 HV0.3, which is about 2.5 times that of the substrate.

Interface improvement of plasma cladded Ni-based coating on copper induced by substrate preheating

To further clarify the characteristics of plasma cladding on copper surface, the effect mechanism of preheating temperature on the interfacial connection of Ni-based coatings was investigated. Results showed that metallurgical bonding can be achieved between coating and copper substrate only when the preheating temperature reached at least 500°C. Without preheating, the heat of the plasma arc was conducted away by the copper with high thermal conductivity, making it difficult to form a molten pool. At low temperatures (300°C and 400°C), the copper oxides formed on copper surface during preheating had poor wettability with the liquid Ni-based alloy, resulting in unreliable interfacial connection. Properly increasing (above 500°C) the preheating temperature can promote the removal of copper oxides, thereby improving the interfacial wettability. Moreover, to avoid performance degradation caused by excessive dilution ratio, controlling the preheating temperature at about 600°C is more appropriate.