Alloy Surface Research Articles

Preparation and Corrosion Resistance of Superhydrophobic Composite Coatings on Shot-Peened AA 7075-T6 Aluminum Alloy

In order to further improve the corrosion resistance of 7075-T6 aluminum alloy after shot peening, corrosion-resistant superhydrophobic coatings (EP-HDTMS@SiO2) containing epoxy resin (EP), cetyltrimethoxysilane (HDTMS), and nano-silica (SiO2) were prepared by a simple spraying method on the surface of shot-peened AA 7075-T6 aluminum alloy. The effects of different EP/SiO2 mass ratios on the micro-morphology, surface wettability, and corrosion resistance of the superhydrophobic composite coatings were analyzed. Due to the combination of microstructure and the modification of low surface energy organics, the contact angle of EP-HDTMS@SiO2 coatings reached the superhydrophobic level (152.6°). The electrochemical tests showed that the corrosion current densities (Icorr) of the EP-HDTMS@SiO2 composite coatings were both significantly lower than those of the EP-HDTMS coatings and matrix aluminum alloys. The addition of SiO2 nanoparticles could improve the hydrophobicity and corrosion resistance of epoxy-based composite coatings. Due to the increase in surface roughness and epoxy resin, the shot-peened AA 7075-T6 alloy coating had high adhesion after the peel test. The prepared coatings also showed excellent corrosion resistance in the neutral salt spray test. This study provides a simple method for preparing stable superhydrophobic coatings on metal surfaces, which is expected to expand the application of 7075 aluminum alloy in harsh environments.

Titanium Implant Modified With Zinc-Doped Carbon Dot Layer as an Innovative Coating for the Development of Local Drug Delivery System for Ciprofloxacin.

This study presents a new innovative drug delivery system for ciprofloxacin, which is based on the formation of a zinc-doped carbon dots layer on the surface of a titanium alloy (TiAl4V6). In the study, the effectiveness of the synthesis method of a zinc-doped carbon dots layer was determined. The distribution of the layer of carbon dots on the surface of the titanium alloy was investigated using the FT-IR mapping technique, which confirmed the efficiency of the synthesis. The effective synthesis of carbon dots and the coordination of zinc ions on their surface opens the possibility of sorption of ciprofloxacin, which results in a high application potential of the obtained biomaterial. The introduction of zinc cations on the surface of the carbon dots layer resulted in high sorption results of the active substance (40 μg of drug per 1 cm2 of implant). The release profile of ciprofloxacin from the modified surface of the titanium alloy indicates that this active substance can be released for up to 4 h. The biomaterial obtained in this work is also hydrophilic (about 40°), which was shown by the contact angle tests. This is an important feature and indicates a high application potential of the performed modification. The resulting layer has antibacterial properties. Growth inhibition for microorganisms such as Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillus cereus, and Candida albicans ranged from 74% to 96%. The creation of such a layer on the titanium alloy may reduce the risk of infection during the implantation procedure.

Waterborne superhydrophobic bio-epoxy coating on Al alloy for corrosion-resistant and self-cleaning applications

Aluminum (Al) and its alloys are important engineering materials in modern industry due to their numerous advantages and have been widely used in various fields, including aerospace, marine, civilian industries and so on. However, they are prone to corrosion and contamination under harsh environmental conditions, particularly in marine environment when exposed to salty water or moisture for a long time, which can adversely affect their aesthetic appearance and desired functionalities or even cause economic losses and serious accidents. To prevent or delay the corrosion, the hydrophilic nature of Al and its alloy surfaces can be transformed to be hydrophobic or superhydrophobic. In this study, we reported an environment-friendly waterborne superhydrophobic bio-epoxy coating (WSBC) without using volatile solvents. The coating is composed of bio-epoxy resin, nano silica, silane coupling agent as well as hydrophobic curing agent, and applied by spin method on Al alloy substrates. The surface morphology and roughness were characterized by a field emission scanning electron microscope (FESEM) and an atomic force microscope (AFM). The WSBC with 22.2 wt% nano silica loading without considering the solvent of DI water displays a water contact angle (CA) as high as 165.8 ± 3.3° and a sliding angle (SA) as low as 5.3 ± 2.5°. Electrochemical measurement results showed that the as-prepared WSBC has a significant shift from −1.160 V to −0.708 V in the corrosion potential (Ecorr) and 3 orders of magnitude decrease in the corrosion current density (Jcorr), indicating excellent corrosion resistance. The WSBC was further proven to function well after immersion in deionized (DI) water and common organic solvents including ethanol and acetone for 48 h, and weathering resistance test. In addition, the as-prepared WSBC also showed good self-cleaning performance. The developed coating is green and no harm to human health and environment. The facile and eco-friendly process is of great importance for many industrial applications which can provide an attractive way towards anti-wetting surfaces for corrosion protection and self-cleaning effect on a variety of engineering substrates.

HA and Fe-based alloy amorphous composite coating on the surface of degradable magnesium alloy

HA and Fe-based alloy amorphous composite coating on the surface of degradable magnesium alloy

Enhancing the Surface Mechanical Properties of AL2618 Alloy Turbochargers Using a PLD Device with AI2O3

Abstract Pulsed laser deposition (PLD) has become a widespread technology for the fabrication of multicomponent thin films Material. In this research, the Microstructure phase, composition and effect of paint made from A nanomaterial (Alfa- Al2O3) were study, A Pulsed laser deposition used in order to improving mechanical performance of aluminum alloy (AL-2618) of turbocharger blades, The main advantages of using it in the manufacture of turbocharger blades to reduce corrosion and erosion, and to ensure high hardness and long-life fatigue, The Pulsed laser deposition used for turbocharger blade, to deposit a layer of aluminum dioxide (10 m) on the surface of the aluminum alloy. The mechanical properties of the blade improved where the hardness of the samples examined and conducted an (EDX) test before and after the deposition process. It was found that after depositing a Nano-layer of aluminum dioxide (Al2O3), the hardness increased and the corrosion and erosion were reduced.

Phase-Field Approach to Formation of Aluminum Oxyhydroxide Nanofibrils on a Liquid Aluminum Alloy Surface in Water-Containing Atmospheres

Formation of peculiar nanofibril structures on the surface of liquid aluminum alloys as a result of chemical reaction of aluminum with water vapors was well studied experimentally for various alloy components starting from mercury. However, the mechanism of nanofibril formation remains unclear to date, and the lack of an appropriate theoretical model does not allow evaluation of the structure parameters depending on the process conditions. We assume that the interface layer between the liquid metal phase and the atmosphere, containing the water vapor, develops certain inhomogeneities respect to the content of hydroxyl groups. That provides areas of suppressed and enhanced diffusion of the aluminum from the liquid phase toward the atmosphere contact. Phase-field modeling, taking into account their elastic interaction, demonstrates formation of the array of nano-islands, enriched with hydroxyl groups, which can be precursors for formation and growth of nanofibrils with elements of pre-boehmite structure.

Effect of Nb content on the tribological properties of laser-cladded Ti-Al-C MAX phase composite coatings

Ti-Al-C-Nbx (x = 0, 2, 4, 6, and 8 at%) composite coatings are prepared on the surface of TC4 titanium alloy via laser cladding. The effect of Nb content on the microstructure, hardness and tribological properties of the Ti-Al-C-based coatings are investigated. The results show that the coatings are composed of Ti₃Al, TiC, Ti₂AlC, Ti₂AlNb, and Ti₃AlC₂ phases. In the coating with an Nb content of 2 at%, a large amount of flocculent Ti₃AlC₂ phase precipitated. This is attributed to the solid solution of a small amount of Nb into the Ti₃AlC₂ phase, promoting the heterogeneous nucleation of Ti₃AlC₂. With the increase of the Nb content, more Nb atoms are incorporated into the Ti₃AlC₂ phase through solid solution, causing the decomposition of Ti₃AlC₂ into Ti₂AlC and TiC. When the Nb content is 8 at%, the flocculent Ti₃AlC₂ phase almost completely disappeared. The Ti-Al-Nb matrix, hard TiC particles and Ti3AlC2 MAX phase form a composite structure with synergistic effects. This enhanced the friction and wear reduction properties of the coatings and reduced the hardness difference between the matrix and the reinforcing phases.

Osteogenesis promotion on MC3T3 by micro-area potential difference (MAPD) on titanium alloy.

The ability of osseointegration of implants is an important factor in ensuring the long-term stability of bone implants in their recipient sites. In this paper, Ti-M titanium alloys with different surface micro-area potential difference (MAPD) were prepared and the adhesion, proliferation, spreading, and differentiation behavior of osteoblasts (MC3T3) on the surface of Ti-M alloy were investigated in detail to reveal the effect of MAPD on cell compatibility and osteogenic differentiation. The results showed that the alloy with high MAPD exhibited facilitated bone differentiation, demonstrating that MAPD significantly enhanced the alkaline phosphatase activity and mineralization ability of osteoblasts, and upregulated the expression of osteogenic differentiation-related factors. It is suggested that it might be a strategy to promote the surface bioactivity of titanium alloy by adjusting the surface MAPD.&#xD.

Morphology and Properties of the Laser-Irradiated Composition “Chrome Coating — Copper Substrate”

Introduction. During pulsed laser processing and modification of the surface of non-ferrous alloys and coatings based on them, several still unresolved issues arise. In particular, the extreme thermal deformation conditions of laser processing are not linked to the peculiarities of structure formation and formation of properties in irradiated “coating — copper substrate” compositions. A metal physical analysis of the possibility and reasons for increasing the adhesion strength of coatings to a metal (copper) substrate during high-speed laser processing is insufficiently substantiated and evidence-based. To make a reasonable choice of technological parameters for the surface hardening mode of non-ferrous alloy products, as well as for obtaining high-quality workable composite layers on their surface, it is necessary to solve the above issues and tasks. The aim of this article is to determine the possibility and conditions for increasing the adhesion strength of a chrome coating to a copper substrate under laser irradiation of the composition.Materials and Methods. Metal physical studies in the work were carried out on samples of non-ferrous alloys of the Cu–Zn system with a chrome electrochemical coating with a thickness of 20 μm. The “copper substrate — chrome coating” composition was irradiated at a Kvant-16 installation with a radiation power density of 70–250 MW/m2. Metallographic structural analysis, scanning probe microscopy, and durometric studies were used in the work.Results. It has been calculated that the dynamic and thermal stresses arising in the laser-irradiated compositions “chrome coating — copper substrate” were about 320 MPa. Metal physical studies revealed that, in extreme thermal deformation conditions of laser treatment, the effect of contact melting was manifested at the boundary of the coating with the copper base. Dynamic recrystallization occurred in the surface layers of the irradiated L62 copper alloy, resulting in the formation of grains with a size of 4.5–5.0 μm on the surface of the alloy with an initial grain size of 25 μm.Discussion and Conclusion. It has been found that the adhesion strength of a chrome coating to a copper alloy substrate increased laser irradiation at a radiation power density of 150 MW/m2. This was due to the formation of a transition region 2–4 μm deep in the contact zone with a structure consisting of sections of mutually insoluble solid solutions based on chromium and copper. Based on the analysis of the copper —chromium state diagram and the model of the temperature field under laser irradiation of the chromium coating, it was suggested that contact melting occurred in the transition zone from the coating to the copper substrate. It was shown that thermostrictive stresses, the calculated quantitative values of which were about 320 MPa, had an initiating effect on the observed processes of structure formation in the laser irradiation zones. It was found that such a level of stresses arising in copper alloys under laser irradiation was sufficient for plastic deformation and dynamic recrystallization of the metal and contributed to the formation of a fine-grained structure (4.5–5.0 μm) with an initial grain size of 25 μm. An analysis of the results of studies of irradiated compositions "coating — copper substrate" allowed us to conclude that they expanded the technological capabilities of the laser method of hardening materials and ensure guaranteed high performance of irradiated products with coatings

Effect of ZrB2 on microstructure and wear properties of TC4 alloy coatings by laser direct energy deposition

In this paper, ZrB2/TC4 alloy coatings with different contents of ZrB2 were prepared on the surface of TC4 titanium alloy using laser direct energy deposition technology. The effects of ZrB2 content on the microstructure, phase, microhardness and friction and wear behaviors of the TC4 coating were investigated, and the enhancement mechanism of ZrB2 on the coating properties was analyzed. The results show that with the increase of ZrB2 content, the coating successively produces the white ring-like structure of the first and the last, the parallel structure of the fishbone and the staggered structure of the TiB compounds, and the microstructure of the coating is transformed from the elongated grains to the fine grains. The microhardness and wear rate of the 15 wt% ZrB2/TC4 coating reached up to 352.1HV and 5.9 × 10−6 g/N•m, respectively. Compared with the 100%TC4 coating, the microhardness is increased by 14.6 % and the wear rate is decreased by 52.0 %, indicating that the addition of ZrB2 was beneficial to improve the friction and wear properties of coating. Interestingly, when the content of ZrB2 reached 20 %, the brittleness of the coating was too high, leading to the phenomenon of grooves on the wear surface of the coating, and the wear rate was reduced by only 45.5 %.

Carob fruit extract as naturally products corrosion inhibitor for copper-nickel alloys in brine solutions

Copper-nickel alloys are the preferred material for desalination facilities and condensers and heat exchangers that use saltwater as a coolant. The eco-friendly compounds especially Carob fruit extract (CFE) has emerged as excessive green corrosion inhibitor for alloys. Cu-Ni alloys are widely used in various industries due to their excellent corrosion resistance. However, their performance can be compromised in aggressive environments like seawater (which is approximately 3.5% NaCl). To evaluate the corrosion behavior of these alloys and the effectiveness of corrosion inhibitors, researchers often employ weight loss, potentiodynamic polarization, and impedance spectroscopy techniques. The results showed that CFE exhibited a good ability to decrease the CR of alloys in 3.5% NaCl solution. The inhibition efficacy (IE) was reached to 92.6% and ̴ 83.2% at 300 ppm dose of CFE for Cu-10Ni alloy and Cu-30Ni alloy, respectively. The CR increases with temperature rising, but the addition of CFE reduces the CR, and the reduction depends on the dose of the extract. Adsorption of the extract gives a good fit to Langmuir, Temkin, and Freundlich isotherms model. The free adsorption energies of CFE on Cu-10Ni and Cu-30Ni alloys were 17.61 and 15.86 kJ mol−1, respectively, suggesting that CFE was weakly held to both alloys. The presence of a protective film on the alloys surface is confirmed by using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy and atomic force microscope (AFM). The study suggests that utilizing affordable, natural substances as green corrosion inhibitors presents a new strategy for promoting both resource efficiency and environmental sustainability.

Atomic mechanisms of oxidative behavior of ferrochromium alloys by water-oxygen environment

The formation of chromium-rich oxide layers on the surface of Fe-Cr alloys significantly impacts their performance at elevated temperatures. Understanding the formation process of these oxide layers at the atomic scale is crucial for further elucidating oxidation behavior, though it presents substantial challenges. In this study, ReaxFF molecular dynamics simulations were used to investigate the oxidation behavior of Fe-Cr alloys in high temperature water vapor and oxygen environments. The results demonstrate that chromium atoms are the primary contributors to the oxidation process, with Cr atoms diffusing to the surface more readily than iron atoms, leading to uneven stress distribution and creating high-stress regions near the Cr atoms. Additionally, hydrogen atoms generated from the breakdown of water molecules infiltrate the alloy matrix, promoting the creation, movement, and clustering of cation and anion vacancies, thereby enhancing oxidation reactions in high-temperature, humid conditions. The study further analyzes electron transfer during single-atom chemical reactions and explores the linear relationship between varying Cr content (10 %–30 %) and oxidation behavior under identical environmental conditions. These findings provide an important theoretical basis for optimizing the performance of Fe-Cr alloys for applications in high temperature environments.

Electrochemical corrosion behavior of α-titanium alloys in simulated biological environments (comparative study).

Titanium (Ti) and its alloys are widely utilized in orthopedic and dental applications due to their favorable mechanical properties and biocompatibility. Notably, titanium exhibits excellent corrosion resistance and can form a stable oxide layer, ensuring the longevity and functionality of implants in challenging physiological environments. This study investigates the corrosion behavior of α-Ti alloy in physiological saline solutions, emphasizing the role of key biomolecules found in the human body, including albumin, glycine, and glucose, as well as additional substances such as hydrogen peroxide (H2O2) and hydroxyapatite (Hap). A comprehensive suite of techniques-namely, open-circuit potential measurements, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and atomic force microscopy (AFM)-was employed to assess the effects of these biomolecules on corrosion behavior. The findings indicate that, unlike H2O2 and Hap, the biomolecules studied significantly enhance the corrosion resistance of the α-Ti alloy in simulated physiological environments. H2O2, due to its strong oxidative properties, accelerates corrosion, while Hap induces ion release that adversely affects the alloy's stability. The observed improvement in corrosion resistance is attributed to the formation of a stable passive layer on the alloy's surface. Notably, this study presents the first long-term electrochemical and immersion tests conducted at 310 K, elucidating the effects of bovine serum albumin (BSA), H2O2, glycine, glucose, and Hap on the corrosion performance of the α-Ti alloy.

Microstructural and tribological properties of multilayered coatings developed through heat treatment on the surface of CP-Ti

It is well known that applying NiTi intermetallic coatings on the surface of different alloys can improve their tribological behavior. In this paper, various intermetallic phases of Ni3Ti, NiTi, and NiTi2 and a Ti-rich pearlite-like eutectoid structure were in situ synthesized on the surface of commercially pure (CP) titanium grade 2. Nickel electroplating was performed on titanium samples followed by heat treatment at a temperature of 800 °C for various times up to 8 h. The formation of various phases and structures along the depth were studied using SEM, EDS and XRD. Heat treatment at a temperature of 800 °C for 4 h resulted in the formation of a multi-layered composite of Ni3Ti, NiTi, and NiTi2 intermetallic films with a thickness of 5, 9, and 2 μm, respectively. A nickel diffusion layer (NDL) with a pearlitic structure containing nanolayers of αTi-NiTi2 was also formed beneath the NiTi2 layer even after 30 min of heating. Among the different layers formed on the surface of CP-Ti, the titanium-rich NiTi (51–52 at.% Ti) showed the highest hardness of more than 400 HV. Sliding wear tests were performed under a normal load of 10 N and the surfaces of wear tracks were studied using SEM. The results showed higher wear resistance of all intermetallic layers and NDL than the titanium substrate, with the highest wear resistance for Ni3Ti top layer.

Investigating the Tribological Properties of the High-Hardness, Low-Young's-Modulus 60NiTi Alloy: A Combined FEM Simulation and Experimental Study

ABSTRACT This study investigates the tribological properties of the 60NiTi alloy, known for its high hardness and low Young's modulus, using a combination of finite element method (FEM) simulations and experimental analysis. A discrete modified Archard model was employed to establish a FEM of a 60NiTi plate paired with a Si3N4 ball, with CSS-42L bearing steel serving as the comparison material. The analysis focused on stress distribution, wear depth, and wear rate to assess the suitability of 60NiTi as a bearing material. The FEM results indicated that, under a 30N load, the peak stress in 60NiTi was reduced by 22.7% compared to CSS-42L, demonstrating the alloy's superior load-bearing capacity. Post-experimentation, both surface and subsurface hardness of the 60NiTi alloy increased, aligning with the stress distribution predicted by FEM, thereby confirming the model's accuracy and reliability. This study highlights the potential of 60NiTi alloy for applications requiring robust wear resistance and stress management under varying load conditions.

Self‐Supported Metallic Alkaline Hydrogen Evolution Electrocatalysts Tolerant for Ampere‐Level Current Densities

AbstractElectrocatalytic water splitting is an attractive approach for large‐scale hydrogen generation, critical for global carbon neutrality. However, the prevalent commercialized alkaline water electrolysis is generally conducted at low current densities due to sluggish kinetics and high overpotential, severely hampering high‐efficiency hydrogen production. Exploration of hydrogen evolution reaction (HER) electrocatalysts that can reliably operate at ampere‐level current densities under low overpotentials is thus a primary challenge. In contrast to extensive studies using powdery electrocatalysts, the self‐supported metallic catalytic cathode has become a burgeoning direction toward ampere‐level current densities, owing to their integrated design with intensive interfacial binding, high conductivity and mechanical stability with industrial tolerance/adaption. Recent years have witnessed tremendous research advances in designing self‐supported metallic electrocatalysts. Therefore, this flourishing area is specially summarized. Beginning with the introduction to the theory and mechanism of alkaline HER, the engineering strategies on self‐supported metallic electrodes are systematically summarized, including metal and alloy construction, heterostructure engineering, doping manipulation, and surface design. Meanwhile, particular emphasis is focused on the relationship between structure, activity, and stability under ampere‐level HER. Finally, the existing challenges, requirements of industrial‐scale application, and future direction for designing electrocatalysts are summarized, aiming to provide a better solution for industrial alkaline water electrolysis.

Effect of Surface Melting and Chromium Surface Alloying on Wear Behavior of Ductile Iron

Effect of Surface Melting and Chromium Surface Alloying on Wear Behavior of Ductile Iron

In Situ Rapid Preparation of the Cu-MOF Film on Titanium Alloys at Low Temperature.

Titanium alloys are widely used in marine environments and medical fields due to their excellent corrosion resistance and high specific strength. However, their good biocompatibility can lead to severe biofouling, thereby limiting their effectiveness. To inhibit biofouling on the surface of titanium alloys, this study proposes an antifouling solution, which involves the in situ preparation of Cu-MOF film on titanium alloys by leveraging the antibacterial properties of Cu ions. Here, the dense and stable TiO2 film on the surface of Ti-6Al-4V titanium alloy was removed by alkali-heat treatment; meanwhile, a porous surface structure was simultaneously obtained where OH- ions were retained. In the subsequent step, the retained OH- ions in the pores attracted Cu2+ ions in solution to form Cu(OH)2 in the pores, providing active sites for the formation of Cu-MOFs. Subsequently, Cu(OH)2 reacted with organic ligand (1,3,5-benzenetricarboxylic acid, BTC) at room temperature to form Cu-MOFs in the pores, which then grew quickly to cover the alkali-heat-treated surface within 1 h. The formation mechanism of Cu-MOF film on Ti-6Al-4V was elucidated, which provides a reference for designing and preparing multifunctional MOF film in situ on titanium alloys. The stability of in situ-grown Cu-MOF samples and their inhibitory effects on bacteria and microalgae have also been verified. The results indicate that although the stability of Cu-MOFs is relatively poor, their bactericidal and algicidal effects are extremely significant, suggesting that this material has significant potential for short-term applications that require high antibacterial performance.

Recent Advances in Aluminum Alloy Surface Treatment Technology and Bonding Properties

Aluminum alloys are widely used in lightweight automotive structures due to their excellent properties. To deeply explore the development of surface bonding technology, aluminum alloy is selected as the object, and current research status of aluminum alloy surface treatment methods is reviewed. The adhesion mechanism during joint preparation, the method of adhesive selection, and the bonding process are summarized. This overview discusses the impact of different surface treatment processes on aluminum alloy joints from two perspectives: substrate characteristics and joint failure modes. It examines how these processes affect surface roughness, surface morphology, surface contact angle, surface free energy, surface chemical composition, and bonding performance. Additionally, it looks ahead to key directions for future research on adhesive joint performance. The results indicate that surface treatment increases the surface roughness of aluminum alloys, reduces the contact angle, and improves surface wettability. Moreover, chemical elements or functional groups that enhance adhesion are introduced on the surface, improving the bonding capability between the adhesive and the substrate. Compared to single‐surface treatment methods, hybrid treatment methods significantly enhance the surface characteristics of aluminum alloys and are expected to become a primary focus for future research on bonded joint performance.

The effect of laser texturing of the surface of a titanium alloy on the adhesive strength of adhesive joints

The effect of laser texturing of the surface of a titanium alloy on the adhesive strength of adhesive joints