Journal of Materials Engineering and Performance最新文献

Superhydrophobic surfaces show promising application potential in anti-condensation and anti-frosting fields, and their performance is closely related to the fabrication techniques employed. The objective is to investigate the droplet condensation characteristics on aluminum alloy surfaces treated by different processes under varying temperature and humidity conditions. This study adopts three processes to prepare superhydrophobic aluminum alloy surfaces, including laser engraving, chemical etching, and spray coating. The results demonstrate that the chemically etched superhydrophobic surface (CES) has superior hydrophobicity with a 156.1° contact angle. Its maximum droplet coverage is only 42%. The laser-engraved superhydrophobic surface (LES) also offers superior overall performance. It shows the slowest radius increase rate and exhibits minimal sensitivity to temperature and humidity. Although the spray-coated superhydrophobic surface (CSS) offers the lowest humidity sensitivity, simple operation, and low fabrication cost, its droplet coverage is significantly high. The research results provide an experimental basis for the surface processing methods used for heat exchangers operating under different temperature and humidity conditions.

The present study explores the effect of an electrodeposited nickel layer on Inconel-718 alloy produced using different additive manufacturing (AM) routes, like Laser Powder Bed Fusion (L-PBF), Electron Beam Powder Bed Fusion (EB-PBF), and Laser-Directed Energy Deposition (L-DED). Comparative analyses were conducted by characterizing the physical, mechanical, and surface properties of Ni-coated AM-built Inconel-718 alloy surfaces. Different microstructures of Ni coatings were observed for different AM-built surfaces of Inconel-718 alloy. Influence on the Ni-layer hardness was also noted, plausibly as a consequence of variations in the residual stress of coated specimens. The hardness of Ni-coated specimens was not correlated well with the scratch resistance due to the unique natures of the Ni layer interface with the substrate surface, depending upon the AM route adopted to produce the Inconel-718 alloy builds. A comprehensive analysis of the scratch failure in identically coated specimens built using different AM routes has also been discussed.

In order to enhance the corrosion resistance of AZ91D magnesium alloy in chloride media, a superhydrophobic composite coating was developed through a process involving zinc-based phosphating, hydrothermal treatment, and stearic acid modification. Initially, a zinc-based phosphating film was prepared in a phosphating solution comprising Na₃PO₄ 12H₂O, ZnSO₄ 7H₂O, NaNO₂, and NaF. Subsequently, micro-nanostructures were grown in an alkaline hydrothermal system composed of ZnSO4 7H2O and sodium citrate. The formation of a low-surface-energy layer was achieved through the process of stearic acid impregnation. SEM, XRD, XPS, and EDS analyses revealed a multilevel rough surface morphology composed of radial petal-like and plate-like structures, primarily consisting of ZnO, Mg(OH)₂, and zinc/magnesium stearate. Wetting tests demonstrate that the contact angle of the coating firstly increases and subsequently decreases in accordance with rising ZnSO₄ concentrations. At a concentration of 0.04 mol/L, the contact angle reaches 160.6°, with a rolling angle of approximately 7°, thereby achieving a typical superhydrophobic state. Electrochemical impedance spectroscopy indicates that the composite coating enhances charge transfer resistance by approximately seven orders of magnitude compared to the bare AZ91D sample, with low-frequency impedance |Z| reaching 109 Ω cm². Following a 168-h immersion in a 3.5 wt.% NaCl solution, the mass loss of the coated sample was found to be negligible, the solution pH remained essentially unchanged, and the surface Cl content after corrosion was only about 0.1%, a result that significantly outperforms that of the substrate. The system has been demonstrated to provide highly efficient and stable corrosion protection for magnesium alloys through the synergistic action of Mg(OH)₂ sealing and the hydrophobic stearate layer.

An extruded AZE311 Mg alloy has been developed and prepared to examine the effect of the precipitated phase on corrosion and hot deformation behavior. High-temperature compression experiments show that dynamic recrystallization (DRX) occurs at various experimental parameters (473 to 673 K and 1 × 10⁻⁴ s⁻¹ to 1 × 10⁻³ s⁻¹). The deformation mechanism is dominated by dislocation slip and/or twinning. Al₁₁Nd₃ precipitates with two different sizes could impede nucleation and the growth of DRXed grains. The serrated flow at low temperature and low strain rate is due to the interaction between dislocations and precipitates. The corrosion current density decreases with the addition of Nd elements. Moreover, the continuous precipitation of the Al₁₁Nd₃ phase at grain boundaries reduces the corrosion rate in 3.5 wt.% NaCl solution, thereby enhancing the corrosion resistance of AZE311 alloys.

Graphical Abstract

Q690 high-strength steel is widely used in marine engineering structures because of its excellent mechanical properties and corrosion resistance. However, the prestrain that is inevitably generated during manufacturing and forming processes significantly alters its in-service behavior. To address this issue, in this study, the corrosion behavior and postcorrosion mechanical property evolution of Q690 high-strength steel under simulated seawater conditions at various prestrain levels were systematically investigated. By applying prestretching deformations of 0, 4, 7, and 10%, combined with accelerated corrosion tests, microstructural characterization (by OM, SEM, EBSD, and XRD), and uniaxial tensile tests, the influence mechanisms of prestrain on the corrosion rate, microstructural evolution, and mechanical property degradation were analyzed. The results indicate that prestrain significantly increases the yield strength and tensile strength of Q690 high-strength steel while reducing its ductility. Concurrently, prestrain accelerates corrosion progression in seawater environments, with corrosion rates increasing with increasing prestrain magnitude. Notably, prestrain effectively delays the postcorrosion decreases in yield strength and tensile strength, although this delaying effect diminishes under higher prestrain conditions. Building upon these findings, a mechanical parameter degradation model and a stress–strain model that account for the combined effects of prestressing and corrosion duration were established, thereby enabling effective prediction of the postcorrosion mechanical behavior of Q690 high-strength steel. The results provide a valuable theoretical reference for the performance evaluation and engineering application of formed high-strength steel structures in marine environments.

Electroless Ni-based ternary alloy coatings provide a cost-effective route to enhance the mechanical and electrochemical performance of aluminum alloys. In this work, a cerium salt-based conversion coating (CeCC) was applied to electroless Ni-Cu-P coatings deposited on squeeze-cast Al-Cu-Mg alloy, with treatment times of 15-60 min. The effect of post-treatment heat exposure at 120 °C was also evaluated. Structural, morphological, and surface characteristics were analyzed using x-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, and atomic force microscopy, revealing a dense Ni-Cu-P layer uniformly decorated with spherical CeO₂/Ce(OH)₂ nanoparticles. Electrochemical measurements demonstrated a marked improvement in corrosion resistance, with the Ni-Cu-P/Ce30-HT coating exhibiting the lowest corrosion current density (~ 0.09 μA cm⁻²) and highest polarization resistance (~ 4.16 × 10⁵ Ω cm²). Mott–Schottky analysis indicated the formation of a bipolar (p–n) passive film with reduced donor density, which effectively suppressed chloride ingress and metal ion dissolution. This synergistic electroless coating and sealing strategy significantly enhanced corrosion protection of Al-Cu-Mg alloys in saline environments.

With the growing demand for lightweight, high-performance titanium alloy components in the aerospace industry, it is critical to develop surface treatment technologies that provide effective protection in extreme environments. The Ti6Al4V SLM component indicates the cross section comprises martensite, columnar crystals, and small defects. The main crystal phases of the coatings are anatase-TiO₂, rutile-TiO₂, and Al₂TiO₅. Additives W and Mo are effectively incorporated into the coatings, generating MoO₂, MoO₃, WO₃, and WO_x. The porosity decreased from 24.7 ± 0.03 to 14.7 ± 0.04%. The microhardness increased from 402 ± 30 HV (the substrate) to 1108 ± 30 HV (Mo-containing coating), an increase of 2 times. Mo has the best high-temperature oxidation resistance, with a weight gain decreasing from 1.817 × 10⁻⁵ mg cm⁻² s⁻¹ to 1.749 × 10⁻⁵ mg cm⁻² s⁻¹. The high-temperature process reduces the weak XRD peak.

Additively manufactured Inconel/GRCop-84 is a candidate material for rocket nozzles. In this study, we explored the effects of space radiation on the stability and integrity of representative Inconel/Cu interfaces using atomistic simulations with previously validated interatomic potentials to assess their viability for extraterrestrial applications. We examined the mechanochemistry of the constituent elements and their effects on radiation resistance across two Inconel variants: Inconel 625 (Ni₇₂Cr₂₃Fe₅) and Inconel 718 (Ni₅₅Cr₂₁Fe₂₄). Our findings reveal three distinct stages—i.e., linear, exponential, and plateau—in the relationship between Frenkel Pair (FP) defect density and radiation damage. FP defect clustering planes were identified on both the Inconel and Cu sides, with Stacking Faults (SF) and Lomer-Cottrell (LC) locks forming on the Inconel side. Moreover, we determined that the orientation of the FP defect clustering planes was influenced by shear stress. We also found that a higher Fe concentration reduces diffusivity between metallic layers, while a higher Cr concentration, owing to its low migration energy barrier, enhances diffusivity.

Using rice husk-derived crystalline nanosilica as a sustainable precursor, a multifunctional PVDF–potassium-doped magnesium ferrite magnetic nanocomposite was successfully fabricated through an injection-molding technique. The novelty of the present work lies in the synergistic integration of agricultural waste-derived nanosilica with alkali-metal-doped ferrite within a PVDF matrix to achieve enhanced multifunctional properties suitable for advanced electronic and energy-related applications. Structural investigations confirmed the formation of a phase-pure and structurally stable composite, while FTIR analysis revealed characteristic Si-O, Fe-O, M-O, and α/β-PVDF bonding. SEM observations demonstrated uniformly distributed spherical nanoparticles with minimal agglomeration due to improved interfacial interaction and surface energy effects. Thermal studies showed a significant enhancement in thermal stability, with Tmax increasing from 479.1 to 565 °C owing to strong interfacial contacts and homogeneous nanoparticle dispersion. Magnetic measurements indicated a transition from diamagnetic to ferromagnetic behavior, with coercivity increasing from 184 to 224 Oe, whereas the diamagnetic contribution of nanosilica resulted in controlled saturation magnetization. The incorporation of ferrite also enhanced the dielectric polarization response, demonstrating the composite’s suitability for dielectric applications. Optical studies revealed semiconducting band gap values of 1.75 and 2.16 eV, while negative zeta potential values confirmed excellent colloidal stability. The coexistence of magnetic hysteresis and dielectric polarization within a sustainable polymer matrix highlights the multifunctional nature of the developed nanocomposite and its potential applications in EMI shielding, flexible electronics, magnetic polymers, semiconductors, and energy devices.