Steel Coatings Research Articles

Effect of different overlap cladding transition layer – Austenitic stainless steel coating and defect degree on corrosion resistance

The effects of overlap rate and defects on the corrosion resistance of laser fusion clad austenitic stainless steel coatings were studied. In this paper, the Ni transition layer and Fe-based coating were sequentially prepared on grey cast iron, and the corrosion morphology and corrosion mechanism of the coating were comprehensively analyzed through physical phase, microstructure and electrochemical tests. The coating phase was mainly γ-Fe, which formed strong selective orientation and texture strength at the (100) crystal plane; overlap ratio and defects affected the recrystallization changes, and the stresses near the defects were high. Increased overlap rate (Fe-based alloy 50 % → 66.7 %) could result in microstructure refinement, reduced corrosion rate v (A8 6.22×10−4 g/m2·h→A9 3.12×10−5 g/m2·h), and improved corrosion resistance. Corrosion cracking extended the crack and embrittled the alloy at the tips of the cracks, so that its (|Z|max 0.67 ∼ 1.31×104 Ω cm2) influence on the corrosion resistance was much higher than that of the pore (|Z|max 5.85 ∼ 10.2×104 Ω cm2). The best corrosion resistance of the process was achieved with an overlap ratio of 66.7 % for both the Ni transition layer and the Fe-based coating.

Effect of overlap rate on the microstructure and properties of Cr-rich stainless steel coatings prepared by extreme high-speed laser cladding

In this work, Cr-rich stainless steel coatings at different overlap rates were prepared by extreme high-speed laser cladding (EHLA) technology, and microstructures, elemental distributions, phase compositions, electrochemical corrosion behaviors, and frictional wear properties were analyzed. The results indicated that increasing the overlap rate enhanced the coating's surface quality and microstructural density. The grain sizes of the coatings at overlap rates of 60 %, 70 %, and 80 % were 2.63 μm, 2.08 μm, and 1.14 μm, respectively. The coatings were predominantly composed of martensite and residual austenite, and residual austenite was extensively distributed within the coatings with a high overlap rate. Electrochemical corrosion results revealed that the coating with an 80 % overlap rate exhibited the best corrosion resistance, with a transfer resistance (Rt) of 981.05 kΩ·cm2 and a passive film resistance (Rc) of 227.31 kΩ·cm2, surpassing other coatings. Under the load of 5 N, the coating's wear rate at 80 % overlap rate was 3.91 × 10−6 mm3/N·m, demonstrating excellent wear resistance. The dense microstructure and refined grain structure assisted the coating in forming a stable passive film during the corrosion stage. The enhancement in coating hardness promoted the rapid development of the oxide film, thereby strengthening the coating's wear resistance properties.

Effect of Treatment with Microarc Oxidation Technology on Tribological Properties of Nonvalve Metal Low-Carbon Steel.

Steel is one of the most widely used alloys because of its excellent properties such as high toughness, good workability, and low cost. However, steel has weak wear resistance, which limits its range of applications and service life. We have used the microarc oxidation (MAO) technique to form an Al2O3 ceramic coating on the surface of nonvalve metal low-carbon steel, which is used to enhance the wear resistance of low-carbon steel. Tribological experiments have shown that the coefficient of friction is reduced by 26.9%, hardness is improved, and wear resistance is enhanced after MAO compared to the substrate. Through a series of characterizations, the wear mechanism of the MAO samples was found to be a complex friction mechanism including abrasive wear, adhesive wear, and friction oxidation. After MAO, the wear resistance of nonvalve metal low-carbon steel is improved. The use of steel can be extended and its service life can be prolonged. This innovative approach provides a viable solution for the development of low-carbon steel coatings.

Green based composite polyurethane coatings for steel

Green based composite polyurethane coatings for steel

Dispersed CeO2 Nanorods with Low-Speed Mixing for Mechanical Properties Promotion of PTA Steel Coatings

The plasma-transferred arc technology has been observed to induce preferential grain orientation in multiple directions, leading to nonuniform grain growth within the alloy coating material. The addition of nano-oxides can act as heterogeneous nucleation sites, reducing the preferred orientation of grains. In this study, a low-speed mixing method was employed to coat highly dispersed CeO2 nanorods (CNRs) onto the surface of 14Cr2NiSiVMn alloy powder particles. The aim was to analyze the influence of dispersed CNRs on grain growth orientation in different directions and the refinement and heterogeneous nucleation effect of CNR additives. The addition of 0.5 wt.% CNRs resulted in the refinement of dendritic grains along both the perpendicular and parallel directions to the coating cladding direction, leading to the formation of more uniform equiaxed crystals. The combination of Ce with Si and V elements formed submicron particles, which promoted grain nucleation and reduced defects in the coating. Consequently, the mechanical performance of the sample significantly improved. In the deposition direction, there was a notable improvement in microhardness (20.4%), tensile strength (97.6%), and elongation (59.0%). In the perpendicular deposition direction, the tensile strength increased by 88.1%, and the elongation increased by 33.9%. Additionally, the weight loss due to wear decreased by 44.2%, and the relative wear resistance improved by 79.3%.

Corrosion Protection Performance of PACC and PACC-Metal Oxides Nanocomposites Electropolymerized Coating of Low Carbon Steel

In the current study, a novel conductive polymer poly 6-((4 acetylphenyl) carbamoyl) cyclohex-3-ene-1-carboxylic acid (PACC) was created by polymerized 6-((4 acetylphenyl) carbamoyl) cyclohex-3-ene-1-carboxylic acid (ACC) monomer using the electropolymerization process. The resulting polymer was characterized using Fourier Transform Infrared Spectroscopy (FTIR). The ability of this polymer to protect the alloy from corrosion was studied at temperatures ranging between 298 and 328 K. The ability of these coatings to stop corrosion on the surface was assessed by measuring the corrosion potential (Ecorr) and the corrosion current (icorr) using a potentiostat. Adding nanoscale metal oxides (zirconium dioxide (ZrO2) and magnesium oxides (MgO)) enhanced the efficiency of this polymeric coating. The protection efficiency of the polymer alone was 77.5%; this efficiency increased to 85.0% and 99.7% in the presence of nano ZrO2 and MgO, respectively. Kinetic and thermodynamic parameters (Ea, H, and S) were calculated for uncoated and coated LCS. An atomic force microscope (AFM) studied the coating surface morphology. Electrochemical impedance spectroscopy (EIS) was used to evaluate the coating resistance.

Effect of Samarium Content on Microstructure and Quality of P92 Steel Coating

Effect of Samarium Content on Microstructure and Quality of P92 Steel Coating

Analysis of Blackening Reaction of Zn–Mg–Al Alloy Coated Steel Prepared by Anodizing Process

The rising demand for black-treated steel faces challenges with conventional black painting due to issues like scratching and peeling, impacting corrosion resistance and aesthetics. This study explores an alternative method, anodic oxidation, to blacken the surfaces of galvanized or coated steel plates. Parameters like temperature, duration, current density, and gas type were varied during the blackening process. The investigation aimed to identify key factors influencing the blackening. Scanning electron microscopy observed the morphology, while energy-dispersive X-ray spectroscopy and glow discharge mass spectrometry analyzed the chemical composition distribution. X-ray diffraction and X-ray photoelectron spectroscopy conducted compound crystal structure analysis. Results indicate higher temperatures, longer durations, and higher current densities improve blackening through anodic oxidation. Increased magnesium proportion on the surface leads to roughness and porous magnesium oxide formation, enhancing light absorption and explaining the observed blackening effect.

Effects of Process Parameters on Microstructure and Wear Resistance of Laser Cladding A-100 Ultra-High-Strength Steel Coatings

To improve the hardness and wear resistance of mild steel, A-100 ultra-high-strength steel cladding coatings were prepared on the surface of mild steel by laser cladding. In this study, the effects of laser cladding process parameters on the forming quality, phase composition, microstructure, microhardness and wear resistance of the A-100 ultra-high-strength steel cladding coatings were researched. The results show that the main phase of the coating is martensite and a small amount of austenite. The microstructures of the upper part of the cladding coatings are mainly equiaxed grains, while those of the lower part are mainly columnar grains. With an increase in laser specific energy, the microstructures of the cladding coatings become coarse. When the laser specific energy is 70.8 J/mm2, the microhardness of the cladding coating is the highest, and the maximum average microhardness of the cladding coatings is 548.3 HV. When the laser specific energy is low, the wear of the cladding coatings is mainly pitting, while when the laser specific energy is high, the wear type of the cladding coatings is mainly adhesive wear. Moreover, the microhardness and wear resistance of the cladding coatings are reduced if the laser specific energy is too high.

Improvement in Fretting Wear Properties of AISI 4135 Steel by Laser-Cladded Martensitic Stainless Steel Coatings

Improvement in Fretting Wear Properties of AISI 4135 Steel by Laser-Cladded Martensitic Stainless Steel Coatings

Comparative Study on the Microstructure and Properties of 304 Stainless Steel Coatings Prepared by High-Velocity Oxygen Fuel Spraying and Air Plasma Spraying

Comparative Study on the Microstructure and Properties of 304 Stainless Steel Coatings Prepared by High-Velocity Oxygen Fuel Spraying and Air Plasma Spraying

Microstructural Characterization, Mechanical Performance, and Anti-Corrosive Response of Zinc Multifaceted Coating on Mild Steel

Zinc has attracted significant attention in research due to its cost-effective use as an electrodeposited material, effectively protecting various types of steel from corrosion and wear. However, despite its advantages, zinc has limitations in fully guarding steel against corrosion. Recent studies propose that blending zinc with other metals during the coating process can proficiently shield mild steel from deterioration. The motivation for this study stems from recognizing the restrictions of zinc electrodeposition and the limited exploration of zinc multi-facet composite coatings for mild steel. In this study, the electrodeposition technique was employed to apply a coating to mild steel using zinc and nanoparticles of calcium oxide (CaO) and manganese oxide (MnO2). The coating bath's chemical composition included mass variations of 0-12 g/L for CaO and MnO2, along with 10 g/L each of boric acid, thiourea, and Na2SO4, and 15 g/L of K2SO4 and ZnSO4. The coating process occurred over a twenty-minute period, with a pH of 4.8, voltage set at 3.2V, current density at 1 A/cm2, temperature at 47°C, and stirring rate at 200 rpm. Results obtained from the coated mild steel demonstrated that Zn-6CaO-6MnO2 exhibited the greatest coating thickness at 0.2308 mm, and it showcased impressive corrosion resistance at 2.0618 mm/year. The Zn-CaO-MnO2 coating displayed a substantial deposit of crystallites in its microstructure, assisted by the presence of manganese, contributing to a smoother surface texture.

Effect of Inter-Splat Bonding Quality on the Dependence of Wear Behavior of Plasma-Sprayed Stainless Steel Coating on Applied Load

Effect of Inter-Splat Bonding Quality on the Dependence of Wear Behavior of Plasma-Sprayed Stainless Steel Coating on Applied Load

Benzotriazole loaded polypyrrole/cerium oxide synthesized composite blend within epoxy resin designed as superior coatings against mild steel oxidative corrosion in sodium chloride medium

In the present research work, benzotriazole or BTA-loaded polypyrrole/CeO2 (PCeB) coatings with different weight fractions as 0.5 %, 1.0 %, and 1.5 % blended with epoxy resin (EPR) were prepared and used to inspect the self-healing and corrosion protection behavior of the composite polypyrrole/CeO2 or PCe prior and after the loading of BTA. The synthesized composites were characterized structurally by XRD and FTIR studies and morphologically by SEM analysis. The surface topology of the coatings over mild steel was analyzed through SEM and AFM studies, furthered with the wettability/water resistance of coated surfaces through contact angle measurements, wherein BTA as inhibitor release rate was studied by the ultra-violet spectroscopy to assess the release amount of BTA within 220–400 nm. The corrosion protection of coated samples was evaluated by the potentiodynamic polarization method and electrochemical impedance spectroscopy or EIS, immersing the steel samples in 3.5 % NaCl solutions. There is a positive shift in Ecorr values and the composite PCeB/EPR (1 %) showed a stupendous protection efficiency of 99.95 % after 3 h immersion obtained through the EIS studies. These findings indicate that Polypyrrole/CeO2@BTA could be a potential substitute for persistent anticorrosive coatings for mild steel against aggressive chloride ions.

Research on the microstructure and properties of antimicrobial stainless steel coatings on Q345R alloy steel by electron beam surface coating

In this study, 304 antimicrobial stainless steel coatings were prepared by the electron beam melting of antimicrobial stainless steel powder, in an attempt to enhance the surface properties of Q345R steel. Besides, the effect of Cu-containing 304 powder coatings on the microstructure, mechanical properties, and electrochemical properties of the Q345R surface was investigated. The results indicated that the coating grain was refined, the dislocation density was increased, and both the plasticity and toughness were enhanced after the electron beam surface coating (EBSC) treatment. Additionally, the hardness of coatings was also enhanced under the three beam currents due to grain refinement and dislocation strengthening. At a beam current of 28 mA, the coating hardness reached a maximum of 384.078 HV, representing a two-fold increase compared with the base material (BM) hardness of 131.048 HV. Moreover, the abrasion resistance of the coating was superior to that of the BM. At a beam current of 28 mA, the wear volume and wear rate were minimized to only 10 % of the wear volume of substrates. In galvanic corrosion measurements, the coatings displayed better corrosion resistance than the substrates, and these samples at a beam current of 28 mA exhibited the best corrosion resistance. Overall, the E-beam surface melting 304 stainless steel coating can effectively improve the properties of Q345R carbon steel.

Erosion behaviour of cold sprayed stainless-steel coatings for civil infrastructures: An energetic approach

Along with corrosion, erosion is one of the main causes of damage to civil infrastructures. The continuous impact of fine particles carried by the air produces a deterioration in the elements of these structures. When this damage is significant, these elements are replaced by new ones. In this work, the possibility of extending the useful life of these components by spraying coatings on the damaged areas is proposed. In this sense, repair techniques such as cold spray deposition are possibilities for this purpose. Therefore, this study focuses on evaluating the erosion behaviour of stainless-steel coatings deposited on structural steel. In addition, the erosion results have been correlated with the model proposed by Hutchings, and an energetic interpretation of the erosion process through this model has been proposed. To carry out this study, stainless steel coatings have been deposited on carbon steel substrates to improve their resistance to corrosion. Different spraying temperatures, from 800 °C to 1100 °C, combined with different pressures of the carrier gas, from 40 to 70 bar, have been analysed. The elastic moduli of the coatings, and their stress-strain curve, have been determined by depth sensing indentation tests with Berkovich and spherical tips, respectively. Erosion tests with normal incidence have been programmed to obtain the corresponding erosion rates. From the results of this work, the optimal projection conditions of stainless steel on carbon steel substrates for the repair of civil infrastructures subjected to erosion processes could be identified.

Particle size-dependent anti-corrosion and mechanical behavior of green-graphene composite

In this study, Green graphene (GG) was synthesized from residual agricultural biomass through pyrolysis and prepared various sizes (2D, 37 μm, 45 μm, 53 μm, and 100 μm) via mechanical and liquid phase exfoliation. These GG samples were incorporated into an EP matrix, forming GG/EP composite coatings for carbon steel. Corrosion resistance was assessed via PDP and EIS techniques. The 37 μm-GG/EP composite coating also showed uniform distribution and compact surfaces. The 37 μm-GG/EP composite coating displayed higher corrosion inhibition (99 %) owing to the even distribution of GG within the EP matrix than the uncoated, along with enhanced hydrophobicity, tensile strength (61.3 %), fracture strain (77.2 %), and toughness (90.5 %) than pure EP coating. Improved corrosion resistance, which was found related to three main factors: first, GGs enhance the coating integrity by obstructing pores and flaws, to stop corrosive media from penetrating. Second, the well-dispersed GG sheet lengthens the diffusion pathways for corrosive agents to the carbon steel substrate, consequently lenghtening the corrosion process. Third, at 37 μm size the resititve forcefields of the GG/EP structure become the most effecitve agaisnt the corrosive media. The study also establishes GG as an eco-friendly sustainable alternative of non-renewable resource based mined compounds of Zn, etc. that are universally and traditionally used, for protective coatings.

Microstructure evolution and property of high manganese steel coatings by laser shock assisted laser wire cladding

Field-assisted laser cladding (FALC) overcomes the limitations of laser cladding through the inherent advantages brought about by the use of various auxiliary energy fields (AEFs). Laser wire cladding (LWC) is limited by the common problems of laser cladding but has a promising future due to the extremely high material utilization rate. In this study, a laser shock assisted laser wire cladding (LSALWC) manufacturing process was proposed. In situ laser shock was introduced into the LWC to obtain finer grains structure and improve product performance. LSALWC does not change the composition of the coating, does not require the use of pretreatment and post-treatment, and does not reduce the efficiency of production. Using high manganese steel (HMS) as the model alloy, LSALWC was employed to achieve the expectation of reducing the proportion of columnar grains, refine the microstructure of columnar grains, and transform columnar grains into equiaxed grains. Compared with the sample (LC) manufactured by LWC, the performance of the sample (LSA) manufactured by LSALWC has been improved, the hardness increased from 285 ± 5 HV0.5 to 303 ± 6 HV0.5, the volume wear rate decreased from 2.1 × 10−4 mm3/N·m to 1.7 × 10−4 mm3/N·m, the primary dendrite spacing of the coating was reduced by 11.5%, and the heterogeneity of coating was more obvious. The cladding process under laser shock was studied using a high-speed camera, and the influence of laser shock on the coating was explained. The mechanism of the performance improvement of the LSA sample was explained. This study showed the disturbance of the molten pool was enhanced by laser shock, and the dendrites at the bottom were deflected or even broken. The broken dendrites were dispersed with the liquid flow and became new nucleation sites. Laser shock increased the supercooling during solidification by reducing the temperature gradient in the molten pool, and created an environment conducive to grain nucleation and growth. This process mitigates various issues in the casting process of HMS and provides a novel method for regulating the grain and microstructure of laser cladding. This research delves into the coupling between the AEF and the dynamic behavior of the molten pool, culminating in a model depicting the evolution of laser cladding solidification under the influence of the AEF, which will provide a new perspective for the research of FALC.

Corrosion Resistance and Mechanical Properties of Cr-Rich 316 Stainless Steel Coatings Fabricated by the TIG Process Using Flux-Cored Wires.

Arc welded 316 stainless steel coatings with flux-cored wires are very promising for marine service environments due to their low cost, high efficiency, and satisfactory performance, while they suffers from Cr dilution during the preparation process. Herein, based on the consideration of increasing the Cr content and ensuring the same value of the Cr/Ni equivalence ratio (Creq/Nieq), 316-modified flux-cored wires, 316F (19Cr-12Ni-3Mo) and 316G (22Cr-14Ni-3Mo), were designed under the guidance of a Schaeffler diagram for the improvement of the electrochemical and mechanical properties of 316 stainless steel coatings. The designed flux-cored wires were welded into a three-layer cladding by the tungsten inert gas welding (TIG) process, and the microstructure, corrosion resistance, and mechanical properties of the claddings were investigated. The results showed that 316F and 316G consist of γ-Fe (austenite) and a small portion of δ-Fe (ferrite) as the Creq/Nieq is approximately 1.5. However, due to the higher value of the equivalent Cr content (ECC), 316G has an additional intermetallic phase (σ), which precipitates as a strengthening phase at grain boundaries, significantly increasing the tensile and yield strength of 316G but reducing its plasticity. In addition, the corrosion current density (icorr) and pitting potential (Eb) for 316G are 0.20447 μA·cm-2 and 0.634 V, respectively, while the values for 316F are 0.32117 μA·cm-2 and 0.603 V, respectively, indicating that 316G has better anti-corrosion performance.

Effect of Post-weld Heat Treatment on Microstructure and Mechanical Properties of P91 Heat-Resistant Steel Coating on Mild Steel

Effect of Post-weld Heat Treatment on Microstructure and Mechanical Properties of P91 Heat-Resistant Steel Coating on Mild Steel