Journal of Materials Science最新文献

One of the key challenges in developing mullite–cordierite electronic substrates is achieving phase homogeneity and controlling porosity to optimize thermal conductivity while maintaining a controlled microstructure. We produced precursor powder for mullite/cordierite composites (Mu/C Com.) for use in multifunctional substrates and electronic components using the sol–gel technique at low temperatures. The precursor powders for the (Mu/C Com.) were made utilizing SiO₂ and Al₂O₃ oxides, respectively, from Si(C₂H₅O)₄ and Al (NO₃)₃.9H₂O, respectively. Structural phases were identified using XRD and refined using the Rietveld method. Microstructure, grain size, and elemental composition were examined by SEM/EDX. Density and porosity were measured via Archimedes’ method. XRD showed pure crystalline mullite for all compositions, while cordierite remained amorphous. Increasing cordierite content reduced grain size by 55%, lowered porosity, and increased bulk density (up to 2.643 g/cm³ for Mu-C30). The dielectric constant decreased with both frequency and cordierite content. A temperature-activated rise in ε′ and ε″ above 280 °C was observed. AC conductivity followed Jonscher’s power law, and activation energies decreased from 0.14 to 0.10 eV with increasing cordierite, indicating facilitated ionic transport. The variation in the maximum imaginary component of the modulus and impedance with frequency implies the presence of a non-Debye relaxation phenomenon. These results demonstrate that dense, sol–gel-derived Mu/C composites exhibit low dielectric loss and stable dielectric behavior at high frequency, making them promising candidates for electronic substrates, high-frequency circuit packaging, and ceramic capacitor applications.

This study presents a modular approach for the synthesis of multifunctional affinity sorbents, facilitating molecular separation via magnetic molecularly imprinted polymers. A magnetic propranolol-imprinted polymer (MIP) nanocomposite with superparamagnetic characteristics was synthesized through precipitation polymerization process coupled with coprecipitation methods. Initially, the propranolol-imprinted core–shell polymer was synthesized via a two-step precipitation polymerization. The obtained core–shell MIP particles (epo-MIP) were subsequently converted to MIPdiol through surface hydrolysis. Finally, the MIPdiol particles underwent an in situ coprecipitation process to incorporate Fe₃O₄ nanoparticles onto their shell surfaces, resulting in the formation of the magnetic nanocomposite (MIPmag). The synthesized magnetic nanocomposite was characterized using various analytical techniques. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of surface functional groups, while scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed uniform morphology and well-defined internal structures. Vibrating sample magnetometry (VSM) demonstrated the superparamagnetic behavior of MIPmag with a saturation magnetization (Ms) value of approximately 3.4 A m²/kg, with no coercivity and remanence. Thermogravimetric analysis (TGA) further assessed the thermal stability and decomposition profile of the nanocomposite. The binding capacity evaluation indicated that MIPmag exhibited a significantly higher binding capacity (Q_e = 21.07 mg g⁻¹⁾ compared to the non-imprinted polymer NIPmag (Q_e = 5.96 mg g⁻¹), confirming the presence of specific recognition sites for propranolol within the imprinted structure. Kinetic studies revealed that adsorption equilibrium was achieved within 10 min, indicating rapid and efficient binding of propranolol onto the magnetic MIP. These results demonstrated that magnetic sorbents with tailored molecular recognition sites hold great promise for the selective and efficient removal of propranolol from water systems.

Graphical abstract

The high-temperature performance of traditional Ti60 alloys is limited under extreme temperatures and harsh ocean environments, primarily due to the heterogeneity of the α/β dual-phase structure in the surface oxide film. The significant differences in composition, structure, and growth kinetics between the β phase and α phase oxide films lead to stress concentration, which accelerates cracking or spalling of the oxide layer. In this study, we innovatively employed laser powder bed fusion (LPBF) technology to successfully fabricate a single-phase α' Ti60 alloy, fundamentally eliminating two-phase heterogeneity. We conducted high-temperature oxidation and hot salt experiments on this alloy. The results indicate that under hot salt corrosion and high-temperature oxidation conditions at 600 and 700 °C, LPBF-processed (LPBF-ed) Ti60 alloys exhibit enhanced stability due to the elimination of defects associated with non-homogeneous oxide layer growth. Furthermore, by integrating studies on oxidation/corrosion kinetics with microstructural evolution, we elucidate the degradation mechanisms underlying corrosion in LPBF-ed Ti60 alloys.

Graphical abstract

This study systematically investigates the interfacial diffusion behavior of sintered copper on various metallized substrates (bare Cu, Ni/Ag, and Ni/Au) and its influence on joint performance and reliability. Through microstructure characterization, interfacial diffusion analysis, and shear strength testing, we revealed evolution mechanisms at Cu-Cu, Cu-Ag, and Cu-Au interfaces during sintering and thermal aging. At the Cu-Ag interface, local interfacial strain was found to cause orientation changes and texture randomization within the Ag layer, while the Cu-Au interface exhibited uniform diffusion and the formation of ordered solid solution phases. Among all configurations, Cu-Cu joints achieved the highest strength of 93.3 MPa under optimized sintering conditions (300 °C, 5 MPa, 30 min). Both Cu–Ag and Cu–Au joints demonstrated further strength enhancement after high-temperature aging and maintained stable performance under thermal cycling, confirming the long-term reliability of the sintered copper bonds. These findings provide a scientific foundation for the interfacial design and reliability evaluation of copper-based interconnects in high-power electronic packaging.

Transparent wood composite (TWC) is an innovative material that combines the natural aesthetic of wood with desirable mechanical and optical properties, making it ideal for creative design applications and energy-efficient construction. This study compares three different delignification techniques for producing TWC from rubberwood veneers: lignin modification (Method-I), acid delignification (Method-II), and a novel hybrid approach (Method-III). Each method was evaluated based on treatment duration, structural integrity of the cellulose template, and the resulting TWC characteristics. The hybrid method (Method-III) adopts a combination of peroxide–acetic acid pretreatment, chosen for rapid lignin cleavage, followed by a lignin modification step (Method-I). This approach achieved extremely rapid and high delignification (~ 95%) within two hours, but resulted in notable structural weakness. On the other hand, Method-I, which involves only lignin modification rather than complete delignification, improved handling and mechanical strength of the cellulose substrate. Further, the conventional NaClO₂-based Method-II removed a substantial amount of lignin but compromised structural robustness, resulting in increased fragility. The excessive lignin removal significantly increases the incompatibility between the polymer matrix and the cellulose cell wall resulting in a reduction in both the mechanical properties and the optical transparency of the resulting composite. The quality of TWC depends on achieving an optimal balance between lignin removal and the preservation of the structural integrity of the cellulose template. Although Method-I yielded the best overall performance of the composite, the rapid and scalable hybrid method (Method-III) offers a practical route for the sustainable production of TWC.

Polypropylene (PP) dielectrics are core components of most film capacitors, and their insulating properties have a major impact on the storage density and safe and reliable operation of these capacitors. To further improve the insulating properties of PP films, we use a composite coating consisting of aluminum nitride particles and polyvinyl alcohol, providing a wide bandgap and high dielectric constant. The composite is applied to the surface of hot-pressed PP films to increase the bandgap width on the film surface. Experimental results show that when the AlN particle concentration is 3.5 wt% and the PVA concentration is 5 wt%, the composite film achieves its optimal breakdown field strength and flashover voltage, increasing by 5.21 and 20.15%, respectively, compared to the base film. Compared to the PP film, the coated film also reduces leakage current by approximately 61.62%, demonstrating a superior charge injection suppression effect. Tests including ultraviolet–visible absorption spectroscopy, leakage current measurement, and surface charge dissipation show that the developed composite coating helps increase the film surface bandgap and introduce shallow traps. Particles are assembled on the surface of hot-pressed isotropic PP films simply and easily, suggesting high production scalability for improving the insulating properties of PP dielectrics.

A microbial fuel cell (MFC) is a sustainable and an environmental eco-friendly system which is utilized for treatment of waste and bioelectricity generation simultaneously, using bio-catalytic activity of microorganisms. Its reliability has been tested using fruit biomass as substrate. The MFC consists of two compartments: anolyte contains fruit biomass for biofilm formation, while catholyte contains one of electron acceptors O₂ or K₃Fe(CN)₆. Owing to its electrochemical catalytic activity, a layered double hydroxide (LDH) was used to modify the matrix of carbon felt (CF), resulting in conductive cathode with enhanced power generation capacity. The electrode performances of LDH-based electrodes were investigated by cyclic voltammetry and impedance spectroscopy. The MFC with K₃Fe(CN)₆ as catholyte and CF–LDH as modified cathode yielded the power density 132.31 mW.m⁻² much greater than that obtained previously with HCl and pristine CF (i.e., 25.0 mWm⁻²). Furthermore, the toxic K₃Fe(CN)₆ was substituted by less toxic electrolytes MgCl₂ and AlCl₃. The MFCs displayed power densities 9.84 and 12.0 mWm⁻² for MgCl₂ and AlCl₃, respectively. Within experimental error, the power density obtained in this study by AlCl₃ and MgAl-CF–LDH (i.e., 12.0 mWm⁻²) was twofold higher than that found previously using NiAl-CF–LDH (6.0 mWm⁻²). The substitution of the transition metal nickel by the alkaline earth metal magnesium increased greatly the power generation. The results confirmed the reliability of MFC technology for treatment of fruit wastes by using the superior catalytic LDH-based composite as cathode for the O₂ reduction reaction.

Cu–Ti alloys were prepared by accumulative roll bonding-deformation aging (ARB-DA) process. The electrochemical corrosion behavior was compared with accumulative roll bonding-diffusion heat treatment and aging (ARB-DHTA) alloys, and the corrosion resistance mechanism was revealed. The results show that deeper pits exist on ARB-DHTAed Cu–Ti alloy surfaces with the corrosion time prolongation. ARB-DAed Cu–Ti alloys have relatively flat surfaces, higher film resistance and lower dimensional passivation current density. Length of the passivation interval is about twice longer than that of ARB-DHTAed alloys. Precipitates and special grain boundaries (SGBs) affect corrosion resistance. High-density dispersive nano-precipitates detach from the matrix and attach to the ARB-DAed alloy surface in the initial corrosion stage. Precipitates increase as the corrosion process proceeds, and wrap around the surface to form a dense protective film. As a result, an “enveloping effect” reduces the corrosion rate of Cl⁻ and improves the passivation effect effectively with SGBs.

Flexible capacitive pressure sensors are increasingly important for applications in wearable electronics, healthcare monitoring, and human–machine interfaces. Despite significant progress, many flexible capacitive pressure sensors rely on complex fabrication or exhibit poor mechanical durability, limiting their practicality in real-world applications. In this work, a simple capacitive pressure sensor is developed using an array of potassium chloride (KCl)-modified polydimethylsiloxane (PDMS) microcylinders as the dielectric layer. The effects of microcylinder geometry and membrane thickness on sensing performance are systematically investigated. Numerical studies were performed to evaluate varying extents of deflection caused by different microcylinder geometries. Based on these results, a design of experiments (DoE) approach was employed to guide the fabrication of moulds with optimized parameters using high-precision computer numerical control (CNC) milling. Among the tested dielectric configurations, the KCl-modified PDMS microcylinder array exhibited the best performance, achieving a high sensitivity of 0.1047 kPa⁻¹ over a range of 0.1–10 kPa, a detection limit of 0.244 Pa, and excellent durability over 10000 loading–unloading cycles. The practical utility of the sensor was demonstrated through reliable detection of sign language gestures, touch inputs, and human motion, highlighting its potential for next-generation wearable and interactive devices.

Graphical Abstract