Surface Of Steel Substrate Research Articles

Analysis of the Boronizing Process of High-vanadium Alloy Steel

The high-vanadium alloy steel substrate surface was carried out by solid powder boronizing. The results showed that a certain thickness and compact structure of the boronizing layers could be obtained after boronizing. The thickness of the boronizing layer was about –53 μm; the thickness of the transition zone was about –36 μm, and the boronizing layer was combined with the substrate firmly. The boronizing layers consist of FeB and embed into the substrate like a spider. The alloying elements have little effect on the formation of sawtooth morphology in the boride layers. The thickness of the boronizing layers increased with the boronizing time and temperature increase, and the thickness of the boronizing layer has a parabola relationship with the processing time.

An Armour Structure to Suppress the Brittle Failure of Ceramic Coatings.

The brittle failure of ceramic coatings limits their application in many fields. To address this issue, a novel armoured ceramic coating was developed to suppress brittle failure. First, an interconnected frame microstructure was micromachined onto the surface of a mild steel substrate using a nanosecond laser. Subsequently, a polymer-derived ceramic slurry was sprayed and sintered to obtain an armoured ceramic coating. The laser-micromachined burr-like microstructure of the substrate facilitated adhesion between the coating and the substrate. The results of the mechanical properties test showed that the armoured coating could withstand more than 20 cycles of water-cooled thermal shock at 600 °C, and the peeling area of the armoured coating was approximately three times less than that of the unarmoured coating under a normal load of 1471 N. The laboratory and field corrosion test results indicated that at high temperatures, the corrosion resistance of the armoured coating was comparable with that of the unarmoured coating and was approximately 10 times higher than that of the uncoated sample. The proposed method will aid in suppressing the brittle failure of ceramic coatings and broaden their scope of application in different fields.

Determination of wear resistance of nickel-carbide alloy coating by atmospheric plasma spray technique on 30MnB5 alloy steel used in cultivator blades

The wear that occurs during tillage in agricultural machinery shortens the material’s life and increases costs. This study investigated the microstructure and morphology of cultivator blades coated with atmospheric plasma spray (APS) process and tested under real field conditions using OM, SEM, EDX, and XRD techniques. Abrasion tests were conducted in an area of 110 hectares and under two different soil moisture conditions. Material properties were investigated using hardness and surface roughness tests. The coating process was successful both mechanically and metallurgically by applying Ni-WC ceramic-metal (cermet) powder on the surface of 30MnB5 steel substrate with APS. The oxide and carbide structures detected on the coating surface by XRD studies resulted in a 1.5 times higher coating hardness. Due to the hard carbide phases in the coating matrix, the grooves on the wear surfaces were shallow and narrow compared to the substrate sample. The surface roughness values of the coated sample were approximately two times higher than the substrate sample. Due to the microstructure and high hardness, the coated specimen experienced three times less abrasion in both humidity conditions. The APS method can be successfully applied to the machined parts of tillage machines. In the near future, the cost of agricultural production can be reduced, and the environment can benefit from this method. In conclusion, this study presents a feasible approach to improving the wear resistance of Ni-WC ceramic-metal alloy by plasma spray coating under real field conditions.

Study on diffusion kinetics of chromium and nickel electrochemical co-deposition in a NaCl–KCl–NaF–Cr2O3–NiO molten salt

Abstract The process of preparing surface composite by molten salt co-deposition is the result of the mass transfer of active particles in molten salt, electrochemical reduction, and solid diffusion. In this study, we prepared Cr–Ni alloy/low-carbon steel surface composites in NaCl, KCl, NaF, Cr2O3, and NiO melt salt system successfully, and analyzed the entire diffusion dynamics process, aiming to find out the limiting links and provide ideas for further improving the preparation efficiency. The results show that chromium and nickel ions are simultaneously reduced on the cathode surface through two and one steps, respectively. And an alloy layer with Fe content of 64.52 wt%, Ni content of 28.96 wt%, and Cr content of 6.52 wt% is formed on the surface of low-carbon steel substrate. The average diffusion coefficients of chromium and nickel atoms in the surface composites are 1.16 × 10−14 and 1.44 × 10−14 m2·s−1. The mass transfer process in molten salt is the limiting link in the whole preparation process.

Synthesis and Printing Features of a Hierarchical Nanocomposite Based on Nickel–Cobalt LDH and Carbonate Hydroxide Hydrate as a Supercapacitor Electrode

The hydrothermal synthesis of a hierarchically organized nanocomposite based on nickel–cobalt carbonate hydroxide hydrate of composition M(CO3)0.5(OH)·0.11H2O (where M is Ni2+ and Co2+) and nickel–cobalt layered double hydroxides (NiCo-LDH) was studied. Using synchronous thermal analysis (TGA/DSC), it was determined that the material retained thermal stability up to 200 °C. The crystal structure of the powder and the set of functional groups in its composition were determined by X-ray diffraction analysis (XRD) and Fourier transform infrared spectroscopy (FTIR). The resulting hierarchically organized nanopowder was employed as a functional ink component for microplotter printing of an electrode film, which is an array of miniature planar structures with a diameter of about 140 μm, on the surface of a nickel-plated steel substrate. Using scanning electron microscopy (SEM), it was established that the main area of the electrode “pixels” represents a thin film of individual nanorods with periodic inclusions of larger hierarchically organized spherical formations. According to atomic force microscopy (AFM) data, the mean square roughness of the material surface was 28 nm. The electrochemical properties of the printed composite film were examined; in particular, the areal specific capacitance at different current densities was calculated, and the electrochemical kinetics of the material was studied by impedance spectroscopy. It was found that the electrode material under study exhibited relatively low Rs and Rct resistance, which indicates active ion transfer at the electrode/electrolyte interface.

Electrocatalytic Performance of Micro–Nano-Nickel Electrodes via Magnetic Field-Assisted Jet Electrodeposition Method

Hydrogen production from water electrolysis using transition metal-based catalysts is a hot research topic at present, and the oxygen evolution reaction (OER) will directly affect the efficiency of water electrolysis. In this work, nickel metal electrodes with micro–nanostructures were rapidly prepared on the surface of a stainless steel substrate by magnetic field-assisted jet electrodeposition (MAJE) and the OER performance of the micro–nano-nickel electrode in electrolytic water was mainly studied. By adding magnetic nano-nickel particles to the electrolyte, the nano-nickel particles reached the electrode surface and were firmly adsorbed by the magnetic field with the flow of the electrolyte. The results showed that the surface morphologies and the preferred growth orientation of nickel electrodes changed in MAJE. In MAJE, when the amount of nano-nickel particles was 2 g/L, the micro–nano-nickel electrode exhibited excellent OER catalytic performance with an overpotential of 274 mV at a current density of 10 mA·cm–2 and a lower Tafel slope of 33.2 mV dec–1 under alkaline conditions. This study confirmed that MAJE had certain advantages in the preparation of metal-based catalytic electrodes, which provided an idea for the research of catalytic electrodes for hydrogen production by electrolysis of water.

Corrosion Protection and Heat Resistance of Paints for Outdoor Use.

Innovative heat- and corrosion-resistant coating approaches, applicable in indirect-food-contact outdoor environments, have been developed. Two systems, a direct-to-metal single-layer, polysiloxane-based, oven-dried system and a bilayer, zinc phosphate active pigment-containing, ambient-cured system were developed to overcome the shortcomings of the traditional bilayer, zinc-rich primer-based heat-resistant surface-protective solutions for outdoor cooking equipment, such as barbecue grills. This case study aims to optimize the application conditions, measure and evaluate the impact of surface preparation and compare thermo-resistant and anticorrosive properties of different coating systems focusing on eco-efficiency. The anticorrosion efficiency of the coatings was characterized using salt-spray chamber corrosion tests and electrochemical impedance spectroscopy. The thermo-resistant character of the coatings was tested by cyclic and constant heat treatment, after which the physical integrity of the coatings was evaluated by optical microscopy. In the overall performance of the coatings, the roughening of the steel substrate surface and the thickness of the coatings were also considered as influential parameters. The study revealed that the newly developed coatings have superior anticorrosion performance to the usually applied Zn-rich coating. The Single-layered Coating has excellent corrosion resistance under certain conditions and has the advantage of fast layer application. The Bilayered Coating showed excellent heat- and corrosion-resistance properties even on a surface without sand-blasting.

Microstructure and properties of composite coatings by laser cladding Inconel 625 and reinforced WC particles on non-magnetic steel

Due to the extremely complex and strict service conditions of non-magnetic drill collars, the friction, wear and corrosion will lead to their damage and failure. Therefore, the surface modification technology can be used to substantially improve the surface performance and effectively extend the service life of non-magnetic drill collars. Under this engineering background, the laser cladding technology was employed to fabricate pure Inconel 625 and Inconel 625/WC coatings on the surface of TWZ-2 non-magnetic steel substrate, and the influences of WC content on the microstructure, phase composition, element distribution, microhardness and wear and corrosion resistance of these coatings were analyzed. The experimental results show that the microstructures of pure Inconel 625 and Inconel 625/WC coatings are all composed of planar grain, cellular grain, columnar grain and equiaxed grain successively. The phases of pure Inconel 625 coating are composed of γ-Ni phase and Laves phase. With WC particles mixed into Inconel 625 powder, various carbide phases appear in the composite coatings. The higher the WC content, the more the precipitated carbides formed by the reaction, thus aggravating the segregation of the solid solution strengthening elements. Besides, W and C elements present severe local segregation due to the undissolved WC particles. In terms of the hardening and strengthening effects of WC particles, the microhardness of the coatings gradually increases with the rise of WC content. The wear mechanisms of substrate and coatings are all compound wears, and different wear forms have different priorities. Accordingly, the wear mechanisms would change with the WC content. The higher the WC content, the lower the wear loss of coating, and the better the wear and friction resistance. Moreover, the corrosion resistance of coatings is better than that of substrate. With the increase of WC content, the corrosion resistance of the composite coatings decreases gradually.

Antifouling Coatings Fabricated by Laser Cladding

Laser surface treatment is a very useful technology for the fabrication of functional surfaces. In this study, novel antifouling surfaces are fabricated by laser cladding of TC4 and Ni60 mixed materials in various mass ratios on the surfaces of 316L stainless steel substrates. Parametric studies are carried out to investigate the effects of the mixed powder mass ratios and laser cladding parameters on the antifouling performance of the laser clad coatings (LCCs). The antifouling mechanism of the LCCs is investigated by using the water contact angle/surface energy measurement, scanning electron microscope (SEM) surface observation, and phase composition analysis via XRD (X-ray diffractometer) testing. The experimental results show that the LCCs with Ni60/TC4 mass ratio of 3/7 has better antifouling performance in this study. The antifouling performance of the LCC decreases with the increase in laser scanning speed. Surface energy and surface topography have a significant effect on the antifouling performance of LCCs. In order to get the optimal antifouling performance of LCCs, the Ni60/TC4 mass ratio and laser cladding parameters should be optimized.

Design Rules of Bidirectional Smart Sensor Coating for Condition Monitoring of Bearings

This paper reports a novel monitoring technique of bearings' bidirectional load (axial and radial) based on a smart sensor coating, which is screen printed onto the surface of a cross-shaped steel substrate. To ensure the accuracy and stability of measurement as well as the durability of the printed coating, the developed prototype is built according to design rules commonly used in electronic circuits. The finite element model (FEM) is used to predict the mechanical property of the tested substrate under either unidirectional or bidirectional loads. Regarding the output voltage of the piezoelectric sensor, experimental results are revealed to be well-corelated to the numerical simulation. It is pointed out that the output signal generated from the sensor (electrode) could be particularly affected due to the capacitive parasite coming from the conductive tracks (CTs). Such a phenomenon might be reduced by printing them on the dielectric layer rather than on the piezocomposite layer. The study also investigates a highly anisotropic shape of electrodes (rectangular instead of circle), indicating that the orientation of such electrodes (axial or radial) does affect the output measurement. To sum up, the high performance of a sensor network coating depends not only on the ultimate characteristics of its own materials, but also on its structural design. Such an issue has been rarely reported on in the literature, but is nonetheless crucial to achieving reliable condition monitoring of bearings, especially for multidirectional loads-a key signature of early failure detection.

Recovery Of Zinc from Scrap Steel Using Zinc-Bromine Battery Technology.

Secondary production of steel is known to significantly decrease the CO2 emissions of steelmaking, but only 40 % of steel is produced through recycling, which is made difficult by contamination of scrap resources with nonferrous metals and nonmetal debris. These contaminants include zinc, towards which blast furnace and electric arc systems have a low tolerance (<0.02 wt %). In this work, clean and efficient recovery of zinc from the surface of steel substrates was investigated using a custom-made low-cost membrane-free non-flow zinc-bromine battery (ZBB) that enabled rapid and straightforward integration and removal of steel substrates. The electrical performance of the cell was characterized by charge-discharge profiles, and zinc removal and recovery onto electrodes was characterized by using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). Upon discharging, the cell efficiently removed >99.9 wt % zinc from steel surfaces. On recharging the cell, zinc was re-electroplated onto a carbon foam electrode in an easily recoverable form and with high purity. The process was repeated over 30 cycles to demonstrate robustness. The work shows the importance of the cutoff voltage upon discharging: if less than 0.5 V, the cell co-extracted iron into the electrolyte solution, affecting cell durability and zinc purity. A two-stage process for recovering zinc from scrap steel is proposed, illustrating how ZBB technology could enable efficient and clean recovery of zinc from complex scrap steel resources in the steel industry.

Biocompatible quaternary pullulan functionalized 2D MoS2 glycosheet-based non-leaching and infection-resistant coatings for indwelling medical implants.

Medical implants are frequently used in medicine and reconstructive surgery to treat various pathological and anatomical conditions. However, over time, biofilm formation on the surface of these implants can cause recurrent infections and subsequent inflammatory responses in the host, resulting in tissue damage, necrosis, and re-hospitalization. To address these implant-associated infections, the best approach is to create antimicrobial coatings. Here, we report the fabrication of a biocompatible, non-leaching, and contact-based antibacterial coating for implants using quaternary pullulan functionalized MoS2 (MCP) glycosheets. The cationic MCP glycosheets were coated on the surfaces of polydopamine-modified stainless steel and polyvinyl fluoride substrates through a simple process of electrostatic interaction. The developed coating showed excellent antibacterial activity (>99.5%) against E. coli and S. aureus that remained stable over 30 days without leaching out of the substrates and retained its antibacterial activity. MCP-coated implants did not induce any acute or sub-chronic toxicity to mammalian cells, both in vitro and in vivo. Furthermore, MCP coating prevented S. aureus colonization on stainless steel implants in a mouse model of implant-associated infection. The MCP coating developed in this study represents a simple, safe, and effective antibacterial coating for preventing implant-associated infections.

Effects of Ultrasound on Distribution of Laser Melt Injected WC Reinforced Particles on Stainless Steel Substrate Surface

Effects of Ultrasound on Distribution of Laser Melt Injected WC Reinforced Particles on Stainless Steel Substrate Surface

Effect of Pre-Oxidation on a Ti PVD Coated Ferritic Steel Substrate during High-Temperature Aging

A PVD coating is often applied on the surface of metallic alloys to improve their high-temperature resistance. In the present work, a thin titanium layer (1.2 µm) was deposited by PVD on the surface of a stainless steel substrate before high-temperature exposure (800 °C in ambient air). The underlying idea is that metallic Ti converts into Ti oxide (TiO2) during high-temperature aging at 800 °C, thereby slowing down the substrate oxidation. The stability of the coating with and without substrate pre-oxidation was investigated. Morphological, structural, and chemical characterizations were performed and completed by simulation of the film growth and measurement of the mechanical state of the film and the substrate. In the case of the sample that was not pre-oxidized, the oxidation of the steel was slowed down by the TiO2 scale but spallation was observed. On the other hand, when the steel was pre-oxidized, TiO2 provided more significant protection against high-temperature oxidation, and spalling or cracking did not occur. A combination of different kinds of stress could explain the two different behaviors, namely, the mechanical state of the film and the substrate before oxidation, the growing stress, and the thermal stress occurring during cooling down.

Laser metal deposition characterization study of metal additive manufacturing repair of rail steel specimens

ABSTRACT Research on rail steel repair with Stellite 6 powder using a laser metal deposition process was investigated and reported in this study. Rail failures due to excessive wear and other rail head defects can increase the risk of operation and reliability problems in service life. This study examines the deposited material compatibility of a cobalt-based alloy, Stellite 6 with the head-hardened R350HT grade rail steel substrate. Materials characterization work includes metallurgical, wear, and shear properties testing and analysis. Microstructural analysis and hardness measurements of the cross-section from raster scan pattern deposition strategy of Stellite 6 on rail steel substrate surface showed minimal dilution and high hardness of the deposited layer with no presence of defects. Experimental testing of rail wear was conducted using a laboratory ball-on-disc tribometer setup and the wear coefficients for Stellite 6 and rail steel were derived from the wear volume analysis using Archard’s wear model. The material interface bond strength was evaluated from shear testing and analysis to measure the shear interface strength of the metallurgical bond between deposited material on a rail steel substrate.

Corrosion protection mechanisms of graphene oxide-reinforced polypropylene coating for mild carbon steel by advanced molecular dynamics simulations with emphasis on resistance to water and chloride ion penetration

Polypropylene can be used as a raw material for manufacturing corrosion-resistant coatings to protect the surface of the mild carbon steel substrate. To improve the properties of polypropylene (PP), graphene oxide (GO) can be added to the coating. In this research, molecular dynamics (MD) simulations were employed to evaluate the effect of GO additives on the PP coating using COMPASS Force-Filed of the Forcite module. The results of molecular modeling, such as mean square displacement (MSD), diffusion coefficient, concentration profile, and gyration radius (Rg), revealed that the permeability of corrosive agents, including water molecules and chloride ions in the composite coating (PP/GO), is much lower than pure one (PP). In addition, by reducing the surface energy from 77 to 68 mJ/m2, the water contact angle (WCA) is improved from 150◦ for the pure PP coating to 170◦ for the composite one. It can also be due to an 18% increase in system compaction in the presence of GO. In the other hand, the free fraction volume (FFV) in the presence of GO is reduced by about 4%. The adhesion of the coating to the mild carbon steel substrate has also been ameliorated by 38% for the PP/GO coating compared to the pure PP. Therefore, most of the simulated parameters reported the positive effects of compositing PP with GO.

Thermal insulation and anti-vibration properties evaluation of modified epoxy resin-based thermal protection coatings in arc-jet

Thermal protection system (TPS) is crucial for hypersonic flight vehicles to effectively protect them against the aerothermal effect imposed on them during flying with high Mach number. A novel hybrid ablation thermal protection coatings (FHMP-ATPCs) on the surface of stainless steel substrate were prepared by doping iron trioxide (Fe2O3) powder, hollow glass microspheres (HGM) and mica powder (MP) into hydroxyl-terminated silicone oligomer-bridged epoxy resins (PSG) copolymer. The thermal insulation and structural reliability of the FHMP-ATPCs were investigated by a novel aerothermal-vibration coupling test system. During the test, the heat flux of the surface of coatings ranged from 400 kW/m2 to 700 kW/m2. Meanwhile, the vibration load was a random vibration with frequency range of 20–2000 Hz and root mean square of total acceleration (Grms) of 10.8 g. The maximum surface and back-face temperature reached 714.9 °C and 141.3 °C, respectively. Compared with epoxy resin based coatings，the PSG-based coatings showed excellent structural reliability during the test. This study demonstrates the robust effect of strategy of modifying epoxy resin with organosilicon in improving thermal insulation performance yet maintaining the structural reliability of the ablation thermal protection coatings, providing a promising route to achieve high-performance coatings.

Evaluation of Biocompatibility of 316 L Stainless Steels Coated with TiN, TiCN, and Ti-DLC Films

In this study, TiN, TiCN, and Ti-diamond-like carbon (Ti-DLC) films were coated on 316 L stainless steel (AISI 316 L) substrate surface by physical vapor deposition. The biocompatibility of the three films (TiN, TiCN, and Ti-DLC) and three metals (AISI 316 L, Ti, and Cu) was compared on the basis of the differences in the surface morphology, water contact angle measurements, CCK-8 experiment results, and flow cytometry test findings. The biocompatibility of the TiN and TiCN films is similar to that of AISI 316 L, which has good biocompatibility. However, the biocompatibility of the Ti-DLC films is relatively poor, which is mainly due to the inferior hydrophobicity and large amount of sp2 phases. The presence of TiC nanoclusters on the surface of the Ti-DLC film aggravates the inferior biocompatibility. Compared to the positive Cu control group, the Ti-DLC film had a higher cell proliferation rate and lower cell apoptosis rate. Although the Ti-DLC film inhibited cell survival to a certain extent, it did not show obvious cytotoxicity. TiN and TiCN displayed excellent performance in promoting cell proliferation and reducing cytotoxicity; thus, TiN and TiCN can be considered good orthodontic materials, whereas Ti-DLC films require further improvement.

Wear-resistant Fe68Cr8Mo4Nb4B16 glass former coatings – From powder production by gas atomization to coating build-up by Laser Powder Bed Fusion

Fe-based glassy/crystalline alloys are promising cost-effective protective coatings to increase the service life of engineering components operating in a wide array of aggressive environments. In this work, gas-atomized 53–106 μm Fe68Cr8Mo4Nb4B16 (at.%) powders, produced from commercial-grade precursors, were deposited onto an AISI 1020 steel substrate by Laser Powder Bed Fusion (L-PBF). The coatings were thick (500–700 μm), dense (2–3%vol. porosity), hard (> 1000 HV0.5), metallurgically bonded to the substrate with reduced dilution, and their microstructures were composed of M2B-tetragonal and ferrite within the remaining glassy phase. Nevertheless, some cracks were observed. Good wear resistance characterizes the L-PBF coatings, with a specific wear rate of ~8.40 × 10−5 mm3/N·m, much lower than the value obtained from the soft (~114 HV0.5) AISI 1020 substrate, 1.91 × 10−4 mm3/N·m. The wear mechanism observed on the coating surfaces was predominantly abrasive and by fracture originated from preexisting cracks. In addition to abrasive wear, the occurrence of oxidative wear was also observed on the worn surface of the substrate. The protective coatings produced by L-PBF proved to be an interesting approach to protect and to repair the surface of steel substrates from wear, besides highlighting the use of L-PBF for coating production.

Enhanced corrosion and wear properties of H13 steel with Co‐based alloy coating prepared by laser cladding

AbstractIn this study, Stellite 21 Co‐based alloy coating was prepared on the surface of the H13 steel substrate by laser cladding. The phase composition, microstructure, chemical constitution, microhardness, and wear property of the coating were studied, respectively. The corrosion resistance of the coating was evaluated by electrochemical test and salt spray test. The results show that the coating is mainly composed of γ‐Co, CoCx, and Cr7C3 phases. γ‐Co solid solution matrix separates within the dendrites, while Mo‐rich intermetallic phases and carbides separate in the interdendritic regions. The average microhardness of the coating is twice that of the H13 substrate. The wear loss of the coating is 74.3% lower than that of the substrate, exhibiting better wear resistance. The main strengthening mechanisms of the coating are solid solution strengthening and second phase strengthening. The self‐corrosion potential of the coating is more positive than that of the H13 steel and the corrosion current density is only 1/160 of the H13 steel. The salt spray test after 168 h reveals that the coating exhibits much better corrosion resistance than that of the substrate.