Nickel-based Alloy Coatings Research Articles

Microstructural analysis of flame-sprayed and PTA-deposited nickel-based self-fluxing alloy coatings

In this paper, the results of microstructural analyses, including optical microscopy, scanning electron microscopy with energy dispersive spectroscopy and X-ray diffraction analysis, of the Ni-based self-fluxing alloys NiCrBSi, NiCrBSi–WC, and NiBSi–WC deposited on a previously quenched and tempered (QT) steel substrate 42CrMo4 by flame spraying with simultaneous fusing and plasma transferred arc (PTA) process are presented. The aforementioned microstructural analysis was carried out to determine the microstructural characteristics of the investigated coatings, especially at the coating/substrate interface, and the influences of the spraying and welding technology on the steel substrate. The analysis revealed a change in the microstructure of the coating/substrate interface. Specifically, the diffusion characteristics of certain chemical elements (carbon and iron) from the coating to the substrate and from the substrate to the coating were observed. Additionally, the analysis established the existence of new phases within the coating that arose as a result of the aforementioned diffusion and reaction with chemical elements from the coating. The diffusion of chemical elements was most pronounced in the area of the coating/substrate interface, while it decreased away from this area.

Influence of W/Cu Ratio on the Dry Sliding Wear Characteristics of Annealed Nickel-Based Poly Alloy Coatings

Influence of W/Cu Ratio on the Dry Sliding Wear Characteristics of Annealed Nickel-Based Poly Alloy Coatings

Microstructure and performance optimization of laser cladding nano-TiC modified nickel-based alloy coatings

In this study, different alloy powders containing nano-sized TiC were prepared using a combination of mixed ball milling adsorption, electroless Ni-P-TiC, and Ni-B-TiC plating techniques. The effects of different nano-TiC addition methods on the microstructure, wear resistance, and corrosion resistance of laser-coated nickel-based self-fusing alloy coatings were comprehensively studied. The effects of the nano-TiC method on the microstructure, wear resistance, and corrosion resistance of laser-coated nickel-based self-fusing alloy coatings were comprehensively studied. The results show that agglomerated TiC particles appeared in the coatings prepared with ball-milled powder. In contrast, the coatings produced by introducing nano-sized TiC through the chemical plating methods exhibited a uniform distribution of the TiC phase. The coatings prepared with Ni-B-TiC plating powder showed a bimodal microstructure and most of the TiC particles are distributed at grain boundaries, which hinders grain growth and refines the microstructure of the coating. The corrosion resistance of the Ni2 coating prepared with ball milling adsorbed nano TiC powder shows the best corrosion resistance. The wear resistance of the Ni4 coating prepared with the Ni-B-TiC plating powder was significantly better than that of the other samples. This study provides an effective way to improve the wear or corrosion resistance of laser cladding nickel-based self-fluxable alloy coatings.

Optimization of SD-3 Nickel-Based Alloy Coating by Single Channel Laser Cladding Using Orthogonal Experimental Method

Optimization of SD-3 Nickel-Based Alloy Coating by Single Channel Laser Cladding Using Orthogonal Experimental Method

Investigation on the high-temperature oxidation behavior and mechanism of laser-cladded Inconel625 coating at various temperatures

This study examines the high-temperature oxidation behavior of laser-clad Inconel 625 coatings under different temperature and time conditions. The coating's microstructure, compositional elements, and oxidation products have been characterized through various analytical methods, including Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), and Laser Confocal Microscopy. The experimental results showed that as the temperature increased in the isothermal oxidation process, the mass of the coatings increased, and the mass gain followed a parabolic relationship with oxidation time. The rate constant exhibited an exponential relationship with temperature. Both oxidation time and temperature had significant effects on the composition and formation of the oxide layer. At lower temperatures, the oxidation process is slow, with an oxidation weight gain of approximately 0.00053 mg/cm2. However, above 600 °C, the oxidation films began to form rapidly, increasing by 0.0169 mg/cm2. Moreover, as the temperature rose, different types of oxides formed at various temperature regimes. At 800 °C, the oxidation film had a thickness of approximately 3.75 μm and a weight gain of 1.19921 mg/cm2. At this point, oxides such as Cr2O3, Nb2O5, NiO, and spinel NiCr2O4 appeared. When the temperature reached 1000 °C, the oxidation film expanded to approximately 63.88 μm in thickness, with a weight gain of 3.5326 mg/cm2. The oxidation products at this temperature were Cr3O4 and spinels NiCr2O4, CrNbO4, NiNb2O6. These findings contribute valuable insights for understanding the dynamic behavior and assessing the service life of laser-clad nickel-based alloy coatings subjected to high-temperature oxidation corrosion.

Preparation and Characterization of Tin-Nickel Coatings for Corrosion Protection of PEM Electrolyzer Components

Hydrogen production by electrolysis offers significant advantages over established and more common processes such as steam reforming with regard to carbon dioxide emissions, in particular through the use of electrical energy from renewable sources and the establishment of a decentralized supply structure. The advantages of PEM (proton exchange membrane) electrolysis include high power density, scalability, and the high purity of the produced hydrogen. However, so far the manufacturing of PEM electrolyzers is time consuming, which makes the widespread use difficult and is a significant cost driver for this technology.In the framework of the publically funded flagship project H2Giga, a series of manufacturing processes are developed for industrial scale-up production of PEM electrolyzer components, in particular the bipolar plates (BPP) and the porous transport layers (PTL). Base materials like stainless steel are used that can be processed at a low cost, but need protective coatings to withstand the highly corrosive conditions during electrolysis, especially at the anode side.A novel approach is focusing on nickel-based alloy coatings, in particular tin-nickel, which emerged as a promising alternative to precious metal coatings. These alloys show a wide stability range under strong anodic polarization in an acidic electrolyte due to the formation of a passive layer. However, the long-term stability does not yet meet the industrial requirements in preliminary tests. A post-treatment of the coating can improve the stability by the formation of a homogenous oxide film with several tens of nanometers in thickness. Physical, chemical and electrochemical methods for post-treatment were compared in terms of oxide morphology and corrosion behavior under anodic polarization. Eventually, both high corrosion resistance and low contact resistance have to be ensured for the application in PEM electrolyzers.

Effect of NbC Addition on the Microstructure and Wear Resistance of Laser Cladding Nickel-Based Alloy Coatings

Effect of NbC Addition on the Microstructure and Wear Resistance of Laser Cladding Nickel-Based Alloy Coatings

Numerical simulation and surface morphology of laser cladding of nickel-based C276 alloy coatings on AerMet100 steel surface

In order to rationally characterize the laser cladding process and effectively predict the processing results, the temperature field and convective heat transfer at the solid-liquid interface were simulated using ANSYS software. Under the selected process parameters, C276 nickel alloy powder was clad on the surface of AerMet100 steel by laser cladding technology, and the microstructure of the cladding layer was observed to investigate the effects of laser power and scanning speed on the laser results. The effect of laser power and scanning speed on the laser results was investigated. The results show that the best coating performance is obtained when the laser power is 1400 W and the scanning speed is 14 mm/s. When the laser power is 1400 W, the scanning speed is increased from 12 mm/s to 16 mm/s, the dilution rate of the coating is increased from 0.385 to 0.423, and the height of the coating is decreased from 0.706 mm to 0.428 mm. When the scanning speed is 14 mm/s, the laser power is increased from 1000 W to 1600 W, the dilution rate of the coating is increased from 0.375 to 0.511, and the height of the coating is increased from 0.393 mm to 0.662 mm. The laser power has a large effect on the height, width, depth and dilution of the coating, while the scanning speed has a large effect on the average particle size of the coating.

Effect of WC Content on the Wear and Corrosion Properties of Oscillating Laser-Cladding-Produced Nickel-Based Coating

Pneumatic conveying pipe is an important part of the coal industry. Its working environment is harsh, and it is mainly affected by serious wear and corrosion, which affects its operating life. Studying a method of strengthening the pipe wall of pneumatic conveying pipe is of great significance. In this paper, nickel-based alloy coatings with different WC (tungsten carbide) contents were prepared using an oscillating laser-cladding process, and the micro-characterization characteristics, wear resistance and corrosion resistance of the laser-cladded layer were discussed. The main conclusions are as follows: The microstructure of the laser-cladded layer gradually grows from the plane crystals and cellular crystals at the bottom to the relatively coarse columnar crystals in the middle, and finally to a large number of equiaxed crystals in the upper part. Moreover, with an increase in WC content, more fine equiaxed crystals are formed, mainly due to the decrease in temperature gradient with the increase in distance from the fusion line. Also, with an increase in WC content, the hardness and wear resistance of the nickel-based alloy are improved. When 20% WC is added, the laser-cladded layer shows the best corrosion resistance in 3.5 wt.% NaCl solution, and its polarization resistance is 16% lower than that when 10% WC is added. This study provides a technical reference for improving the operating life of pneumatic conveying pipelines.

Interface characteristics and properties of nickel-based alloy coatings on cast iron fabricated by plasma and cold metal transfer wire-arc deposition

Interface characteristics and properties of nickel-based alloy coatings on cast iron fabricated by plasma and cold metal transfer wire-arc deposition

Effect of Mechanical Vibration on Microstructure and Properties of Laser Cladding WC-Reinforced Nickel-Based Alloy Coatings

Ni-WC composite coatings on 35CrMoV alloy surface were successfully prepared by mechanical vibration field-assisted laser cladding technology. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to study the microstructure of the composite coatings without vibration and at different vibration frequencies; the phase composition of the cladding layer was studied by X-ray diffraction (XRD); and an energy dispersive spectrometer (EDS) was used for elemental plane scanning analysis. The grain growth trend under different convection directions was simulated. The wear resistance and mechanical properties of the composite coating were analyzed by friction and wear testing machine, three-dimensional surface profiler, and microhardness tester. The vibration field generated by the self-improved shaking table device is used to assist laser cladding. The effect of mechanical vibration on the quality of the cladding layer was studied. The results show that compared with the coating without mechanical vibration, an appropriate increase in vibration frequency contributes to the refinement of the grains. The original coarse dendrite structure becomes a fine needle-like structure, and the fine grain size gradually decreases. The application of vibration can improve the effect of grain refinement. The vibration makes the grain size distribution more uniform and the microhardness fluctuation of the cladding layer decreases. The experimental results show that mechanical vibration can improve the microstructure uniformity of the coating by selecting suitable vibration parameters. The average friction coefficient and wear width are reduced, and the microhardness is also increased.

Effects of Cr contents on tribological and corrosion behavior of HVOF sprayed Ni-based alloy coating

High-velocity oxygen fuel (HVOF) spray process was employed to fabricate nickel-based alloy coatings composed of different chromium contents (NC-A, 7.15 wt%; NC-B, 16.98 wt%). Based on the results of the tribocorrosion test, a mechanical plowing effect can be observed on the coatings at low applied potential (< +100 mVSCE), and the wear behavior of coatings was aggravated by intensified corrosion effect when a higher potential (>+300 mVSCE) was applied. Through the quantitative analyses, we have concluded that the total weight loss (Wtotal) of the coatings increased significantly as a function of the growing potential loading, and the synergic effects between corrosion and wear played a vital role in the overall weight loss.

Cavitation erosion/corrosion synergy and wear behaviors of nickel-based alloy coatings on 304 stainless steel prepared by cold metal transfer

Inconel 625 and Hastelloy C-276 nickel-based alloy coatings were prepared on 304 stainless steels by cold metal transfer (CMT), aiming at improving the resistance to corrosion, cavitation erosion and wear. The synergistic cavitation erosion-corrosion (SCE-C) effect of the coatings was also revealed in 3.5 wt% NaCl solution. Experimental results show that the Inconel 625 coating was composed of γ-phase matrix and MC-type carbide precipitates dominated by NbC, while the Hastelloy C-276 coating exhibited γ-phase matrix and Mo-rich p phase. Both corrosion resistance and cavitation erosion resistance of the Hastelloy C-276 coating and Inconel 625 coating were higher than that of 304 substrate, and the Hastelloy C-276 coating possessed higher corrosion resistance and cavitation erosion resistance than Inconel 625 coating as indicated by higher polarization resistance (152.95 kΩ cm2) and lower mean depth erosion rates (1.3 ± 0.15 μm/h). The carrier concentration ND of passivation film for Hastelloy C-276 coating (4.05 ± 0.01 × 1022 cm−3) was lower after 10h-cavitation erosion compared to Inconel 625 coating, indicating its passive film showing a stronger passivation behavior and protective ability. The Hastelloy C-276 coating also exhibited a higher wear resistance, and the wear mechanism was adhesive-abrasive comprehensive wear dominated by adhesive wear in the linear reciprocating wear test with Al2O3 as the friction pair. The wear resistance of Inconel 625 coating and Hastelloy C-276 coating was about 1.3 and 1.5 times that of 304 substrate, respectively. The Hastelloy C-276 coating fabricated in the present study exhibited a great potential as flow-passing parts in marine engineering fields due to the desirable resistance to corrosion, cavitation erosion and wear.

Effects of Current Density and Deposition Time on Corrosion Behaviour of Nickel-based Alloy Coatings

Corrosion of fasteners is an on-going issue and stainless steel 304 (SS304) is prone to this destructive process. One method to mitigate corrosion is electrodeposition of Co-Ni-Fe nanoparticles. This paper studied the effects of deposition time and current density on corrosion behaviour of Co-Ni-Fe coated SS304 bolt. Co-Ni-Fe ternary alloys were electrodeposited onto SS304 bolt in 15, 30, or 45 minutes by using current density of 28, 35, 42 mA/cm2. Combinations of these parameters produced 9 samples. These samples were electrochemically tested by a potentiostat using open circuit potential (OCP) and potentiodynamic polarization (PDP). The samples were also characterised in terms of surface roughness and thickness of the coatings by using 3D surface metrology system. The OCP value decreased when deposition time was increased. All sample synthesised in 30 minutes had a more stable OCP curve. PDP curves exhibited active behaviour without passivation region. The corrosion potential (Ecorr) of T15 samples was more anodic than T30 and T45 samples. The corrosion current density (Icorr) of all samples fluctuated. Sample synthesised in 30 minutes using 42 mA/cm2 had the lowest corrosion rate. It was found that the surface roughness influences the corrosion behaviour in which a lower surface roughness tends to produce coating with better corrosion performance. Current density had small effect on the thickness of coating, whereas the tendency of a thickness to increase was obvious for deposition time.

Study on microstructure and corrosion resistance of Ti-doped nickel-based alloy coatings

Study on microstructure and corrosion resistance of Ti-doped nickel-based alloy coatings

Cold Spray of Nickel-Based Alloy Coating on Cast Iron for Restoration and Surface Enhancement

Cold spray is an emerging additive manufacturing process that allows particles to be coated onto the surface of a base material without melting. It is suitable to repair components made from temperature-sensitive materials, such as grey cast iron, which cannot be easily restored using conventional methods like welding or thermal spray. In this study, the nickel-based alloy Inconel 625 was successfully coated onto a grey cast iron (GJL250) using a cold spray process, and extensive experiments were carried out to study the effects of diffusion between the coating and the substrate after heat treatment at 400, 600, 850 and 1050 °C for 3 and 6 hours durations. The coatings in all conditions were dense (0.25% to 3%) and had defect-free interfaces. Under heat treatment, the diffusion layer increased in thickness with increasing temperature and duration due to atomic diffusion. The Inconel 625 coating is also shown to be effective against oxide growth as compared to grey cast iron. The hardness of the coatings is also stable at high temperatures. The heat-treated coatings at 600 °C achieved a peak hardness of around 500 HV, which is 30% and 60% higher than the as-sprayed coating and grey cast iron substrate, respectively, because of the possible formation of recrystallized nanostructured grains and strengthening precipitates. These findings demonstrate the potential application of using cold spray on nickel-based alloy coatings for restoration and surface enhancement of grey cast iron components, such as engine blocks and pump housings.

Study of Cracking Mechanism and Wear Resistance in Laser Cladding Coating of Ni-based Alloy

Nickel-based alloy coatings were widely used for the remanufacturing of dies and moulds by laser cladding, but the crack sensitivity would be increase due to the higher strength and hardness, which reduced the wear resistance of Ni-based alloys. In this paper, Ni-based coatings with the addition of a plastic phase (an austenitic stainless net) were prepared using laser cladding technology, and the CeO2 was added in cladding layers. The cracking mechanism, microhardness, microstructure, phase composition, and wear properties were investigated. The relationship between thermal stress and the elastic and plastic fracture had been developed from the standpoint of fracture mechanics and thermal elastic fracture mechanics. The fracture criterion of the nickel-based coating was obtained, and the study has shown that the crack sensitivity could be reduced by decreasing the thermal expansion coefficient Δα. Thus, a new method was proposed, which the stainless steel nets were prefabricated on the substrate. It was found that the number of cracks reduced significantly with the addition of stainless steel net. When the stainless steel net with 14 mesh was added in Ni-based coatings, the average microhardness of nickel composite coating was 565 HV0.2, which was 2.6 times higher than that of the 45 steel substrate. Although the rare earth oxide 4 wt.% CeO2 and stainless steel net were added in the Ni-based coating reducing the microhardness (the average microhardness is 425 HV0.2), the wear resistance of it improved substantially. The wear volume of Ni-based composite coating was 0.56×10−5 mm3·N−1·m−1, which was 85.1% lower than that of 45 steel. The experiment results have shown that the Nickel-based composite coating is equipped with low crack sensitivity and high abrasive resistance with austenitic stainless net and the rare earth oxide 4 wt.% CeO2. This research offers an efficient solution to produce components with low crack susceptibility and high wear-resistance coatings fabricated by laser cladding.

Effect of Vacuum Annealing on the Nickel-Based Coatings Deposited on a CGI Cast Iron through Atmospheric Plasma Spraying

Plasma-sprayed nickel-based self-fusion alloy coatings were annealed in a vacuum at 990, 1020 and 1050 °C for 20 min to increase the bonding between the compacted graphite cast iron substrate and coating, as well as the inner cohesion of the coatings. It was found that nickel and chromium diffused between nickel-based alloy coatings and compacted graphite cast iron substrate. A metallurgical translation zone with a thickness up to 1145 μm formed during the vacuum annealing, which resulted in an enhancement of the adhesion between the coating and substrate. The adhesion strength at room temperature was increased from the as-sprayed coating of 33.4 MPa to the annealed one of 163 MPa. Meanwhile, the adhesion strength at 500 °C reached 146 MPa. Conversely, the inner cohesion of the coating was improved with the particles’ interfaces healed after vacuum annealing. The micro-hardness of the annealed coatings was increased to 902 HV from the as-sprayed one of 578 HV.

Pulse electrodeposition and corrosion properties of nanocrystalline nickel-chromium alloy coatings on copper substrate

Co-electrodeposition of nickel-chromium (Ni–Cr) alloy coating was performed on a copper substrate from a sulfate-chloride bath. The effect of electrodeposition techniques namely direct (DC) and pulse-current (PC) techniques on cathodic efficiency, alloy composition, crystallite size, microhardness, morphology, and corrosion properties of Ni–Cr alloy coatings was investigated. Results show that PC electrodeposition generally produces coatings with desirable properties with respect to DC electrodeposition. Chemical composition measured by energy dispersive X-ray spectroscopy (EDS) and consequently other properties depend on PC parameters including peak current density and duty cycle whose increase rises Cr content of nickel-base alloy coatings. In contrast, PC frequency decreases the Cr content of Ni–Cr alloy coatings. When Cr content increases up to 24 wt% the crystallite size falls down to 66 nm. However, a phase segregation takes place by any further increase of Cr content than 24 wt% and therefore a new phase γˊ appears in the coatings. The surface morphology of the Ni–Cr coatings also changes from large spherical granules with a diameter ranging 27–114 nm to smaller size grain by increasing the Cr content. Above 24%wt. cracks appear on the coating surface. Based on potentiodynamic polarization method, Ni-11.2 wt % Cr alloy coating exhibits the highest corrosion resistance in 3.5 wt % NaCl compared to the other compositions. The corrosion resistance of the alloy coatings is mainly due to the formation of a passive film which in turn is enhanced by increasing the chromium content in the alloy. However, the corrosion resistance drops for high chromium Ni–Cr coatings (>24 wt %) owing to the microcracks developed in the coatings.

Improving the microstructure and mechanical properties of laser cladded Ni-based alloy coatings by changing their composition: A review

AbstractNi-based alloy coatings prepared by laser cladding has high bonding strength, excellent wear resistance and corrosion resistance. The mechanical properties of coatings can be further improved by changing the composition of alloy powders. This paper reviewed the improved microstructure and mechanical properties of Ni-based composite coatings by hard particles, single element and rare earth elements. The problems that need to be solved for the particle-reinforced nickel-based alloy coatings are pointed out. The prospects of the research are also discussed.