Resistance Surface Research Articles

Wettability, droplet impact and anti-icing performance of micro-nano hierarchical structure on Ti6Al4V surface via integrating of chemical modification and laser-induced plasma micromachining

Superhydrophobic functional surfaces are widely used in medical treatment, pipeline transportation, and ship corrosion protection and have great potential in the field of anti-icing. Ultrafast laser-induced plasma micromachining (LIPMM) combined with a chemical modification of a fluoroalkyl low surface-energy substance (Novec) was used to fabricate superhydrophobic surfaces with periodic layered micro-nano arrays on Ti6Al4V. The wettability, droplet collision behavior and wear resistance of surfaces with different physical and chemical properties were analyzed. In terms of static anti-icing, based on the classical nucleation theory, the icing-delay performance of different surfaces was analyzed. Ice adhesion strength and frosting properties were also studied. It was found that the micro-nano structure surface fabricated by LIPMM had strong hydrophobicity (contact angle of 164°, roll-off angle of 1.0°), high icing delay time (3072 s, 4 μL of water droplet on the surface at −10 °C), low ice adhesion strength (38.2 kPa), and better durability. Additionally, the droplets bounced off this surface after colliding at different angles (0°, 5°, 10°, and 20°). This study provides a feasible solution for fabricating anti-icing surfaces on Ti6A14V.

Comparison of the Erosive Wear Resistance of Ductile Cast Iron Following Laser Surface Melting and Alloying

This article presents research results on the influence of the laser surface melting and alloying processes on the erosive wear resistance of ductile cast iron. For the research, an EN-GJS 350-22 ductile cast iron surface was laser-melted and laser-alloyed with titanium powder in an argon and nitrogen atmosphere. Solid-particle erosion tests were carried out on the laser-melted and -alloyed surface layers and the base material according to the ASTM G76-04 standard with 30° and 90° impingement angles. The erosive wear resistance results were correlated with Vickers hardness and microstructural test results with the use of SEM (scanning electron microscopy), TEM (transmission electron microscopy), EDS (energy dispersive spectroscopy), and XRD (X-ray diffraction). The mechanisms of erosive wear were also analyzed for the laser-treated surface layers and the base material. The research showed that the laser melting and alloying processes with titanium powder had a positive effect on the hardness and erosive wear resistance of the ductile cast iron surface due to microstructure modification. Moreover, despite the lower hardness of the laser-alloyed surface layers, their composite microstructure had a positive impact on the erosive wear resistance in comparison to the laser-melted surface layers.

Enhance the tribological performance of soft AISI 1045 steel through a CrN/W-DLC/DLC multilayer coating

Special equipment vehicles typically operate in complex environments, leading to wear and failure of the chassis's rotary seal shaft predominantly made of soft AISI 1045 steel. An effective approach to prolong the service life is to apply a hard coating on the working surface. Previous research have primarily concentrated on the coating for hard high-speed steel. However, the significant disparity in physical characteristics between soft AISI 1045 steel and the hard coating results in a weak interface adhesion. This study produces a CrN/W-DLC/DLC multilayer coating on the soft AISI 1045 steel with strong interfacial adhesion and superior friction and wear property through modulation of the CrN transition layer thickness. The multilayer coating consists of five layers, a CrN transition layer, a Cr layer, a Cr/WC alternating layer, a W-DLC/DLC alternating layer, and the topmost DLC layer. The thickest CrN interlayer coating achieves the Lc2 and Lc3 value of 13.9 ± 0.2 N and 20.4 ± 0.9 N. The optimized CrN/W-DLC/DLC coating reduces the internal stress of the DLC coating and enhances its adhesion. Importantly, the average friction coefficient and wear cross-sectional area of the CrN/W-DLC/DLC multilayer coatings decrease accordingly. The thickest CrN interlayer coating exhibits superior outstanding wear resistance evidenced by an average friction coefficient of 0.119, a steady-state friction coefficient of 0.097 and a wear volume of 1.508 × 106 μm3. The presence of a high proportion of sp2 bonds in the thickest CrN interlayer coating, which are susceptible to graphitization, along with a thicker transition layer that enhances the coating's support, leads to narrower wear traces. The primary wear mechanisms observed in the friction and wear test of CrN/W-DLC/DLC coatings are oxidative wear and tribo-abrasive wear. The work provides a significant promise for application in vehicle rotary seal components and a theoretical reference for enhancing the wear resistance of the seal surface.

Bio-inspired co-deposition of dopamine and N-oxide zwitterionic polyethyleneimine to fabricate anti-fouling loose nanofiltration membranes for dye desalination

Developing anti-fouling loose nanofiltration membranes (LNMs) that can achieve dye desalination of saline textile wastewater through dye retention and salt permeation for resource utilization remains an urgent challenge that needs to be addressed. Inspired by the biomimetic adhesion of mussels and the excellent fouling resistance of saltwater fish surfaces, novel LNMs were prepared through co-deposition strategy using dopamine (DA) and N-oxide zwitterionic polyethyleneimine (ZPEI) as biomimetic functional materials. There are multiple interactions between them, including Schiff base reaction, Michael addition reaction, cation-π interaction and covalent polymerization. Compared with PEI-LNM prepared under the similar method, the optimized ZPEI-LNM displays more uniform surface, smaller average roughness (6 nm vs 22 nm), and denser pore size (0.69 nm vs 0.79 nm), indicating the zwitterionic N-oxide moieties in ZPEI regulate the deposition process and the cross-linking structure of the selective layer. ZPEI-LNM exhibits a high pure water flux of 203.0 L m−2h−1 under 0.6 MPa. Importantly, ZPEI-LNM shows high retention towards different dyes, including Congo red (CR, negative, 696.8 g/mol) of 100.0 %, Acid fuchsin (AF, negative, 585.5 g/mol) of 99.5 %, Crystalline violet (CV, positive, 408.0 g/mol) of 98.2 %, and Indigo carmine (negative, 466.4 g/mol) of 96.0 %, while the rejection of NaCl (8.7 %) and Na2SO4 (12.7 %) are both lower. As expected, for the mixture solution of AF/NaCl, the dyes are efficiently rejected, while salts can pass through, indicating that ZPEI-LNM displays an excellent dye desalination capability. Furthermore, multiple-cycle antifouling tests for bovine serum albumin (BSA) and sodium alginate (SA) reveal that the flux recovery ratios are higher than those of PEI-LNM (BSA: 90.4 % vs 81.9 %; SA: 86.6 % vs 80.5 %), indicating ZPEI-LNM exhibits better anti-fouling performance towards different model foulants owing to the outstanding hydration layer caused by zwitterionic N-oxide moieties and lower surface roughness. Consequently, the work offers a new viewpoint for the fabrication of anti-fouling LNMs via biomimetic strategy for dye desalination.

Prediction of the Skid Resistance of Recycled Hot Mix Asphalt Mixture

Typically, the skid resistance of pavement surfaces is used to indicate road safety levels. The initial value and long-term behavior of skid resistance can be reportedly determined by modulating asphalt mixture properties during their mix design process. In this study, a skid-resistance prediction equation for recycled asphalt concrete was formulated based on ANOVA test results. An accelerated polishing device was used to replicate the abrasion encountered by road surfaces owing to vehicle–tire interactions for characterizing the skid resistance of recycled asphalt concrete. Notably, key parameters, including initial and terminal values and reduction rate of skid resistance induced by vehicle-related abrasion, were determined. These findings suggest that the initial values and reduction rate of skid resistance can be estimated from the mixed binder properties and initial MTD value. However, the final/terminal skid resistance predicted using aggregate gradations has a limited degree of confidence. To further improve the accuracy of the prediction equation, additional data collection and validation tests are required. In addition, field tests using recycled asphalt concrete are necessary to refine the accuracy and precision of the prediction equations for practical road construction scenarios. This study represents a significant step toward the development of safe and effective road infrastructure.

Study on high-temperature friction and wear properties of Arc Ion plating Cr coating

In order to improve the high-temperature resistance and wear resistance of the D60 steel surface, arc ion plating technology is used to deposit Cr coating on the surface of D60 steel. A friction and wear testing machine is used to test the friction coefficient of D60 steel and Cr coating. Scanning electron microscope and Energy dispersive spectrometer are used to characterize the microstructure, composition, and phase composition of D60 steel and Cr coating. The research results indicate that when the temperature is 300°C and the load is 100 N, the friction coefficient of arc ion-plated Cr coating is higher than that of D60 steel. In addition, on the wear morphology, there are adherents and local peeling phenomena on the surface of the Cr coating.

Study on shallow configuration preparation and macroscopic and microscopic properties of cemented carbide surface

This study aimed to reduce surface configuration defects and improve the service performance of the configuration surface. The configuration was prepared using the principle of preset powder feeding laser cladding. Macroscopic and microscopic properties of the shallow configuration were tested to understand the mechanism behind the preset cladding material's ability to repair defects and improve surface hardness, and the preparation process of the shallow configuration was obtained. Finally, the method's potential for improving the wear resistance of the configuration surface was evaluated through friction and wear tests. The results indicate that the flow of molten preset powder can fill in pores, leading to the formation of a dense cladding layer on the configuration surface. This process also minimizes the generation of defects and holes. The incorporation of hard phases, such as TiN, Ti2N, and the solid solution (Ti, W)C1-X, positively influences the improvement of surface hardness and wear resistance of shallow configuration. When the average laser energy density ranges from 70 to 120 W·cm−2, the average microhardness of the shallow configuration surface is elevated by 13.4% compared to that of the conventional configuration surface. The friction force on the shallow configuration surface is 13.1% lower than that on the conventional configuration surface when the laser power is set to 80%, the scanning speed is maintained at 1500 mm/s, the scanning passes are 9, the spacing between configurations is 130 μm, and the configuration diameter is 50 μm. This technique presents a novel approach to producing configuration surfaces with enhanced quality.

Study on the Wettability and Abrasion Resistance of Ultrafast-Laser-Textured Ti Surface

Titanium (Ti) materials are highly valued in the medical field for their outstanding biocompatibility and corrosion resistance. However, challenges such as suboptimal wettability and wear resistance can impact the tribological properties of titanium implants, potentially leading to implant failure. This study explores the application of ultrafast pulsed laser processing to create two distinct structures, circular pits and grooves, on the surface of titanium materials. The samples underwent low-surface-energy treatment, after which the wettability and wear resistance of the textured surfaces were evaluated. The findings indicate that the textured surfaces exhibit improved hydrophobic properties and reduced surface wear. Specifically, the textured surfaces demonstrated a remarkable 73.68% reduction in wear compared to the untextured surfaces. These results underscore the potential of etching textured structures onto titanium surfaces to enhance their wear resistance, thereby offering promising implications for the improvement of titanium implant performance.

Corrosion behavior of HVOF sprayed 304 stainless steel coating on 6061 substrate in 3.5 wt% NaCl solution

This study aimed to improve the corrosion resistance of lightweight material surfaces by applying a 304 stainless steel coating (304SSC) onto 6061 aluminum alloy using high-velocity oxygen-fuel (HVOF) spraying. The phase composition, microhardness, microstructure, and long-term corrosion behavior of the HVOF-sprayed 304SSC in 3.5 wt% NaCl solutions were analyzed through scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and an automated micro-hardness testing system. The findings indicated that the corrosion resistance of the coatings improved as the number of deposited layers increased. Moreover, the coatings that displayed the highest resistance to chloride ion attack in long-term immersion experiments also effectively prevented galvanic coupling. The enhanced corrosion resistance was attributed to reduced porosity, increased densification, and enhanced mechanical stability of the coatings.

Assessing the tribo-corrosion resistance of surface nanostructured stainless-steel

In this work, surface mechanical rolling treatment (SMRT) was applied as a post-process nanostructuring technique to improve the tribo-corrosion degradation resistance of coarse grain (CG) 316L stainless steel (SS). The experimental findings reveal that when tribo-corrosion wear took place, the CG specimen experienced severe surface de-passivation, which increased wear-corrosion synergy and the rate of material loss. On the other hand, the SMRT specimen experienced enhanced re-passivation kinetics, which reduced wear-corrosion synergy and the rate of material loss. The wear mechanism for both the CG and SMRT specimens was abrasion-dominant, with the CG specimen having the presence of micro-pits within the wear track. In addition to these findings, the reduced surface roughness, improved hardness, formed compressive stresses, microstructural refinement, and martensite phase transformation induced by the SMRT process contributed to the enhanced tribo-corrosion resistance of the SMRT specimen. In total, SMRT was found to be a feasible technique to improve the tribo-corrosion resistance of CG 316L SS.

The Coal Quality CICS that Increases the Wear Resistance of Heat Exchanger Tubes

The paper discusses the threat of decommissioning of the thermal power plant (TPP) heat exchanger tubes because of erosion and develops a computer-integrated control system (COAL QUALITY CICS THAT INCREASES THE WEAR RESISTANCE OF HEAT EXCHANGER TUBES) for the process of distribution of steam coal flows with different indicators of abrasive materials content, which is based on fuzzy logic. The problem of rapid decommissioning of TPP heat exchanger, particularly abrasive damage to furnace screen tubes, economizer, superheater, etc. This may indicate a discrepancy between the expected fuel ash content and the actual one, as well as a high content of abrasive impurities in steam coal. The work aims to develop a CICS of the wear resistance of the heat exchange surface of a steam boiler of a coal-fired power plant by measuring and fuzzy control of the content of abrasive impurities in steam coal. The problems of damage to the equipment of the TPP boiler are investigated and a system for controlling the wear resistance of the surface by automatic fuzzy control of the quality of coal is developed. In order to investigate the effectiveness of the proposed fuzzy controller, the results were investigated in a specific example, in particular, during coal preparation and combustion in the furnace of a thermal power plant. The model results confirm the feasibility of the fuzzy control method for the system with different coal quality parameters.

Analysis of electrochemical corrosion performance of 316L stainless steel fabricated and textured by selective laser melting

Textured surfaces were used to increase the electrochemical corrosion resistance of the laser powder bed fusion, corrosion performance, DC corrosion and electrochemical impedance spectroscopy techniques were examined. Corrosion resistance could be optimized as a result of changing the surface energy on modified surfaces and eliminating selective laser melting (SLM)-induced morphological discontinuities. The corrosion resistance of optimum textured surfaces is higher than that of forged samples. Results close to texture-free surface performance were obtained on surfaces where texture density reached maximum. Increasing texture weakened the corrosion resistance. Thus the best corrosion resistance; icorr = 156 nA/cm2 with Ecorr = −327 mV observed at 5CR. Material losses are 49.40 mpy × 10−3 for 5CR, 63.48 mpy × 10−3 for 5SQ, 382.60 mpy × 10−3 for 15CR, 63.33 mpy × 10−3 for 15SQ, 394.6 mpy × 10−3 for 25CR and 174.80 mpy × 10−3 for 25SQ, respectively. The highest performance in terms of material losses was found to be 5CR. No significant change in the context of texture geometry was observed in the SEM images. According to quantitative evaluation in electrochemical corrosion tests, the differences are quite close to each other.

Study of the Effectiveness of Corrosion Resistance Growth by Application of Layered AlN–TiO2 Coatings

The work is devoted to the study of the use of AlN–TiO2 coatings as protective materials against corrosion and natural aging, as well as a rise in wear resistance of the steel surface under long-term mechanical influences. The choice of oxy-nitride coatings obtained by magnetron sputtering by layer-by-layer deposition of layers of aluminum nitride and titanium oxide with layer thicknesses of the order of 50 nm and 100 nm as objects of study is due to their high resistance to external influences, which can have a significant impact on growth in the resistance to degradation processes associated with hydrogenation during the operation of steel structures. During determination of the hydrophobicity/hydrophilicity of AlN–TiO2 coatings, it was found that the applied coatings, regardless of the conditions for their preparation, have hydrophobic properties (the contact angle is ~125–130°), which are preserved both during corrosion tests (except for TiO2 coatings, for which the change in the contact angle after corrosion tests is ∆ ~ 10°) and when modeling natural aging processes. During the tribological tests of coating samples, it was found that a growth in the number of spray layers (when alternating them) leads to a rise in wear resistance, both in the case of the initial samples and for samples subjected to corrosion in a model solution of 0.1 M NaCl and when simulating natural aging processes.

Structural and corrosion analysis of copper/chitosan coating on nanotubular TiO2/Ti6Al4V implant surface

In this research, we focused on the investigation of the structural, surface, and corrosion behavior properties of copper-loaded TiO2 nanotubular array surfaces that were further deposited with a chitosan biopolymer. This composite material was fabricated on Ti6Al4V alloy substrates using a combination of anodic oxidation (AO), electro-cathodic deposition (ECD), and electrophoretic deposition (EPD) techniques, primarily to apply it in medical implant contexts. Initially, the TiO2 nanotubes were prepared via anodization (AO). Subsequently, copper was introduced into the TiO2 nanotubes through electro-cathodic deposition (ECD), followed by the coating of chitosan over the copper-loaded TiO2 nanotubes using electrophoretic deposition (EPD). To comprehensively assess the characteristics of these surfaces, a series of analytical techniques were employed, including SEM, EDX mapping, XRD, and wettability measurements. Furthermore, the electrochemical properties of these surfaces, namely the OCP, PDP, and EIS, were extensively scrutinized.The outcomes of this investigation directed a notable development in the electrochemical corrosion resistance of the chitosan-deposited copper-loaded TiO2 nanotubular array surfaces in comparison to uncoated Ti6Al4V alloy, particularly under conditions simulating a physiological environment (simulated body fluid, SBF). Corrosion rates, assessed through PDP (Potentiodynamic Polarization) curves, were determined to be 0.3023 mm/y for polished Ti6Al4V, 0.1476 mm/y for TiO2 30 V 4 h, 0.1235 mm/y for TNT-Cu2/30/Ch, 0.0733 mm/y for TNT-Cu2/60/Ch, and 0.0611 mm/y for TNT-Cu2/90/Ch. Additionally, corrosion protection efficiencies were calculated as 51.16 % for TiO2 30 V 4 h, 59.15 % for TNT-Cu2/30/Ch, 75.76 % for TNT-Cu2/60/Ch, and 79.81 % for TNT-Cu2/90/Ch. Notably, the TNT-Cu2/90/Ch sample demonstrated a significantly low corrosion rate of 0.0611 mm/year and a high corrosion protection efficiency of 79.81 %. This enhancement can happen due to the chitosan coating, which acts as a protective layer, hindering the ingress of the physical solution into the original metal surfaces. Notably, TNT-Cu2/90/Ch coated sample exhibited a corrosion rate (icorr) approximately 5 times lower than that of the uncoated alloy. In conclusion, this study presents a novel chitosan-coated composite material consisting of copper-loaded TiO2 nanotubular surfaces that effectively enhances corrosion resistance compared to polished Ti6Al4V substrates.

A novel device for investigating the anti-melting loss performance of Ni60A coating on coppery tuyere

Coppery tuyere is a core component in iron-making blast furnace, mainly used for supplying hot air and injecting pulverized coal. Due to the harsh service environment, tuyeres are prone to failure by wear and melting loss. Surface coatings can significantly improve the wear resistance of copper surface, but their anti-melting loss performance is still a research blank. This paper designed a novel device for testing the anti-melting loss performance of coatings. The device included plasma melting-drop, induction preheating and infrared temperature control systems, which can simulate the process of coating being corroded by molten iron under service conditions. Anti-melting loss test results of Ni60A coating indicated that the molten iron and the γ-(Cu, Fe, Ni) solid solution in the coating can form metallurgical bonding by element diffusion, thus adhering on the coating surface. The continuous accumulation of iron will worsen the heat-transfer capability of tuyere, making it more likely to cause melting loss. Adding ceramics in the Ni60A alloy or developing coating materials with higher melting points are expected to improve the anti-melting loss performance of coatings on coppery tuyere.

Study on wear protection performance of HVAF WC–Cr3C2–Ni coatings deposited on crystallizer surface

A crystallizer is the most crucial component of the continuous casting and rolling process, and it is required to operate effectively at high temperatures and loads for an extended period. In this study, WC–Cr3C2–Ni cermet coatings with high strength and wear resistance were deposited on the surface of a copper alloy crystallizer using high-velocity air-fuel spraying. The microstructure of the coating and its protective effect on the substrate at different temperatures were analyzed. The coating on the copper substrate was uniform and dense, with a porosity of 0.34 % and stable phases. Wear test results at room temperature showed that copper substrate underwent oxidative peeling failure when subjected to wear, and exhibited severe abrasive and adhesive wear, while WC–Cr3C2–Ni coating had no peeling damage on the surface when subjected to wear. In addition, the friction coefficient of the substrate was reduced from 0.624 to 0.489, thus significantly improving the wear resistance of the crystallizer surface. At high temperature (300 °C), the friction coefficient of coating increased to 0.676. Although the degree of oxidation and fatigue wear of the coating increased, the surface of the coating remained intact without any failure area. WC–Cr3C2–Ni coating protected the crystallizer continuously under high-temperature loading conditions for a prolonged time, indicating enhanced service life of the crystallizer. This study provides significant findings for developing new crystallizer coatings.

Enhancing the surface finish and corrosion resistance of laser powder bed fusion NiTi surfaces through chemical polishing

NiTi alloys exhibit significant potential for biological applications, and the fabrication of customized NiTi geometries is greatly facilitated by the use of laser powder bed fusion (LPBF) processing. However, there are several challenges with post-processing NiTi specimens processed via LPBF, such as uneven, loosely packed, weakly corrosive surfaces, and low dimensional precision. Therefore, solving the surface problem of metals prepared by LPBF has become the key to the application. In this paper, the influence of the solution and parameters on surface roughness, surface shape and size, composition, and corrosion resistance was studied by adjusting the composition of the polishing solution and polishing parameters. The results show that polishing for 2 h in S2 solution (HNO3: HF: H2O = 40:10:50) produces the smoothest surface with the roughness characteristics Sa is 10.41 ± 0.63 μm and Ra is 0.39 ± 0.30 μm. At the same time, the corrosion resistance of polished samples has been significantly improved in simulated body fluids (SBF), and the corrosion current density (Icorr) reduced by up to one order of magnitude, reaching 5.38 ± 0.24 × 10−8. By altering the polishing process duration, it is possible to achieve a micron-level roughness surface while maintaining dimensional accuracy, making LPBF-NiTi more suitable for implant applications. Ultimately, we conclude with a brief discussion of how chemical polishing affects the handling of materials with complex structures. Between 30 and 1 h, LPBF-NiTi scaffolds were polished in S2 solution to provide porosities and dimensional accuracy that best matched the design parameters.

Construction of wear resistant superhydrophobic structure without degrading the surface mechanical properties of alloy layer

The vulnerability of superhydrophobic surface structures frequently leads to a loss of their superhydrophobicity under friction, significantly restricting their broad-scale applicability. The preparation of alloy layers emerges as an effective strategy to enhance the mechanical properties of metal surfaces. The construction of superhydrophobic structures without loss of mechanical properties of alloy layer is expected to lead to the preparation of superhydrophobic surface with excellent wear resistance. In this study, a superhydrophobic surface with excellent hardness and wear resistance was successfully prepared by a two-step process of electrospark deposition and anodization. The superhydrophobic surface maintained superhydrophobicity under long distance friction. Firstly, alloy layer with micron bulges and excellent mechanical properties was constructed on the metal surface by electrospark deposition, which was then slightly anodized to create hierarchical micro-nano bulges rather favourable to superhydrophobicity, and anodization did not degrade mechanical properties of the surface. The surface is provided with excellent superhydrophobicity after modification with fluorosilane. SEM, 3D profilometer and roughness tester were adopted to explore microscopic morphology of the sample surfaces. XPS and FTIR were used to explore chemical components of the sample surfaces. The element distribution of the sample surfaces was analysed through EDS, and wettability of the sample surfaces was explored through the contact angle test. The hardness test and wear test were applied to explore mechanical properties of the sample surfaces. It was proved through linear friction, droplet impact, hammering and knife scratch that the superhydrophobic surface could maintain good superhydrophobicity under multiple forms of mechanical destruction, while the neutral salt spray test, electrochemical tests and acid and alkali soaking test proved the excellent property of corrosion resistance of the superhydrophobic surface. In addition, the prepared superhydrophobic surface also features an excellent self-cleaning property.

The Effect of La on the Surface Properties of Plasma Nitrided CoCrCuFeNi High-Entropy Alloys at 440 Degrees Celsius

This paper investigates the effect of the element La on plasma nitriding of the CoCrCuFeNi high-entropy alloy (HEA) at 440 °C for 8, 16, and 24 h. The phase composition, morphology, and hardness distribution of the nitrided layer are characterized using XRD, optical microscopy, and a microhardness tester. Furthermore, the corrosion resistance is tested using an electrochemical workstation. The study evaluated the friction and wear performance using a testing machine and scanning electron microscope. The thickness of the effective hardening layer after 16 h of treatment with La was similar to that after 24 h of treatment without La. The addition of La significantly increased the growth rate constant of the effective hardening layer from 0.53 × 10−14 m2/s to 0.72 × 10−14 m2/s. In addition, an expanded FCC phase with greater interplanar spacing can be formed on the surface of the sample by introducing La into the plasma nitriding process. This indicates that the expanded FCC phase, with a higher concentration of interstitial nitrogen atoms, can effectively improve the corrosion resistance of the specimen surface. The corrosion rate of the specimen surface was reduced by 27.5% and the wear rate was reduced by 41.7% after 16 h of treatment with the addition of La compared to 24 h of nitriding without the addition of La. It has been shown that the addition of La to the plasma nitriding process results in a higher quality nitrided layer in a shorter time and also demonstrates that La has the potential to optimize the surface properties of plasma nitrided HEAs.

High corrosion resistance of a novel armored super-hydrophobic Fe-Mn-Si-Cr-Ni coating

In this work, ultrasonic-assisted laser cladding technology was employed to fabricate shape memory alloy (SMA) coatings composed of Fe-Mn-Si-Cr-Ni on the surface of 304 stainless steel. Both experimental and simulated results unequivocally demonstrate a substantial improvement in both microhardness and wear resistance of the metal surface. Subsequently, a superhydrophobic coating with an “armor-like” structure was comprehensively prepared by integrating femtosecond laser (FSL) and nano SiO2 spray-coating techniques. The creation of this microstructure on the coating surface efficiently facilitated the high-efficiency embedding of nano SiO2 particles. Notably, the modified SMA coating exhibited stable superhydrophobic properties and exceptional corrosion resistance. This research not only provides novel approaches and methods for the preparation and modification of Fe-based memory alloy coatings but also highlights potential applications in the corrosion-resistant field. The work offers valuable insights for researchers in the field of materials science, emphasizing the synergistic effects of ultrasound-assisted laser cladding technology, femtosecond laser, and nano SiO2 spraying techniques. It provides robust support for the development of new functional coatings.