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The evolution of various intermetallic layers and the formation of voids at the substrate/coating interface of hot-dip-aluminized (Al-9 wt% Si) hot-press-forming steel were systematically investigated using a field-emission scanning electron microscope and glow discharge optical emission spectrometer. Following austenitization at 900°C for 10 min, the substrate/coating interface of the air-cooled and quenched Al-Si coatings was characterized by the presence of Fe2SiAl2, Fe2 Al5, and a-Fe(Al) layers. The results revealed that rapid cooling/quenching effectively restricts the diffusion of Al, Si, and Fe atoms, leading to the formation of fewer Kirkendall voids within the intermetallic and a-Fe(Al) layers, with a decreased thickness of the latter. Consequently, the quenched Al-Si coating exhibited increased Vickers hardness, indicating enhanced mechanical properties due to the higher cooling rate. [ABSTRACT FROM AUTHOR]

In foil has excellent heat dissipation performance as a commercially available thermal interface material for high power devices. In order to improve the heat transfer performance of In-based thermal interface materials, a composite thermal interface material with In as the matrix and Cu as the reinforcement was prepared in this research by hot press sintering. The Cu–In composite material's characteristic interfacial structure was examined through the use of transmission electron microscopy. Theoretical models were employed to determine the thermal conduction patterns across various CuIn phase interfaces. By fine-tuning the parameters of the hot press sintering process, we were able to regulate the CuIn phase interface layer's morphology. Results indicate that the Cu–In interface is bonded through a reactive interface, leading to the formation of the CuIn phase that is tightly atomically bonded with both In and Cu. The CuIn phase, when continuous, exhibits higher interfacial thermal conductivity as its thickness decreases. Practical fabrication considerations show that the CuIn phase interface transitions from discontinuous to continuous at a thickness of ∼0.91 μm. Therefore, a continuous CuIn phase interface layer of about 0.91 μm thick yields the highest thermal conductivity, reaching 122.25 Wm−1K−1, which is 1.4 times greater than that of pure In. This research presents innovative choices and strategic directions for advancing the field of high-thermal-conductivity interfacial materials.

Copper and its alloys are widely used in the preparation of metal matrix composites due to their thermal and electrical conductivity. This study aims to improve the mechanical, tribological and electrical conductivity properties of copper (Cu) matrix powders by adding certain amounts (10 wt%) of reduced graphene oxide (rGO) nanopowder, boron (B), nitrogen (N) and silicon (Si) reinforced rGO nanopowder. Hybrid composites were produced by powder metallurgy production methods. The samples were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDX) and Fourier‐transform infrared spectroscopy (FT‐IR) analysis for reinforcement, homogeneity and phase identification. The mechanical and tribological properties of the hybrid composites were investigated by hardness, wear tests and temperature dependent electrical conductivity tests to determine the effect of the reinforcement materials on the Cu matrix structure. The maximum hardness value was obtained from the (Cu–rGO–Si–B–N) hybrid composite with an increase of 193% compared to the pure Cu sample. When the coefficient of friction values of RGO and reinforced rGO hybrid composites were examined, a 219.12% lower coefficient of friction value was observed in the (Cu–rGO–Si–B–N) sample compared to the pure Cu sample. The highest value was observed in the temperature dependent electrical resistance analysis in the rGO reinforced sample. [ABSTRACT FROM AUTHOR]

[Display omitted] • Quaternary Ag 2 SbBiSe 4 NCs are synthesized by a colloidal synthesis route. • Ag 2 SbBiSe 4 has a cubic crystal structure and a wide band gap. • Ag 2 SbBiSe 4 maintains low lattice thermal conductivity of ca. 0.34 W m−1K−1. • Modulation doping through Sn NCs is used to tune the TE performance of Ag 2 SbBiSe 4. • A maximum ZT value of 0.64 at 760 K and a high Vickers Hardness of ~185 Hv are obtained. Materials with low intrinsic thermal conductivity are essential for the development of high-performance thermoelectric devices. At the same time, the solution processing of these materials may enable the cost-effective production of the devices. Herein, we detail a high-yield and scalable colloidal synthesis route to produce Ag 2 SbBiSe 4 nanocrystals (NCs) using amine-thiol-Se chemistry. The quaternary chalcogenide material is consolidated by a rapid hot-press maintaining the cubic crystalline structure. Transport measurements confirm that n -type Ag 2 SbBiSe 4 exhibits an inherently ultralow lattice thermal conductivity of ca. 0.34 W m−1K−1 at 760 K. Moreover, a modulation doping strategy based on the blending of semiconductor Ag 2 SbBiSe 4 and metallic Sn NCs is demonstrated to control the charge carrier concentration in the final composite material. The introduction of Sn nanodomains additionally blocks phonon propagation thus contributing to reducing the thermal conductivity of the final material. Ultimately, a peak thermoelectric figure of merit value of 0.64 at 760 K is achieved for n -type Ag 2 SbBiSe 4 -Sn nanocomposites that also demonstrate a notable Vickers hardness of 185 HV. [ABSTRACT FROM AUTHOR]

The development of bio-based adhesives, to the extent possible without harmful chemicals derived from fossil resources, is very important for the sustainable use of wood-based materials. In this study, we investigated the possibility of glycerol as a bio-based adhesive by manufacturing wood-based moldings. The raw materials used were glycerol and wood powder of Japanese cedar (Cryptomeria japonica). The moldings were manufactured under hot-pressed at 160–220 °C and 4 MPa for 10 min. The glycerol content varied from 0 to 30 wt%. Color differences in the resulting molding increased with increasing glycerol content and hot-press temperature, suggesting that chemical changes occur during hot pressing in the presence of glycerol. The best bending properties of the moldings were obtained under manufacturing conditions of 15 wt% glycerol and 220 °C. In the water resistance test using boiling water, weight gain and thickness swelling of moldings were inhibited with increasing glycerol content. The moldings manufactured at hot-press temperatures above 200 °C developed water resistance. Ether linkages were detected by Fourier transform infrared spectroscopy and heteronuclear single quantum coherence nuclear magnetic resonance spectroscopy. Our results demonstrated that good adhesiveness is achieved by ether linkages resulting from the chemical reaction between glycerol and wood powder. [ABSTRACT FROM AUTHOR]

Voids are a common defect in the manufacturing process of composite materials, which can reduce the mechanical properties of components. As an out-of-autoclave (OoA) technology, double-vacuum-bag (DVB) process can achieve low-cost manufacturing of composite materials with low void content. This paper investigated the effect of DVB process on void evolution and laminate properties during the curing process of composites. Different dwelling temperatures were applied, and a single-vacuum-bag (SVB) process was designed as the experimental control group. The curing cycles were completed and the laminates were rapidly cooled at selected time points. This work used a microscope to take cross-sectional images of samples, for statistical analysis of void morphology and void growth behavior. Besides, the density and fiber volume fraction of composite materials were measured by Archimedes method and combustion method. The experimental results show that as the curing cycle progressed, the void content of laminate produced by DVB process continued to decrease. Compared with the SVB process, the dual vacuum environment of the DVB process can timely discharge the stagnant air in the prepregs, thereby reducing the void content, which is at the same level of the composite materials manufactured by hot press with 0.6 MPa. [ABSTRACT FROM AUTHOR]

The high extractives content in rice straw inhibits the reactivity of castor oil-based polyurethane (CPUR) resin and hinders its bonding. This study employed steam treatment to pretreat rice straw to decrease the extractives content before using it for particleboard production. The effects of steam pressure and time on the chemical composition of the rice straw were investigated. Variable parameters tested were steam pretreatment time (5, 10 min) and steam temperature (110, 120, 130, and 140 °C). In addition, the mechanical properties and water resistance of particleboard manufactured from rice straw bonded with CPUR resin were evaluated. A three-phase hot press schedule at 110 °C was adopted. Other production parameters, such as resin content (20 wt%), hot press time (5 mm/s), and board density (800 kg/m3) were held constant. The resulting particleboards were tested for their mechanical properties in terms of modulus of rupture (MOR), modulus of elasticity (MOE), and internal bond (IB). Further, the physical properties including water absorption (WA) and thickness swelling (TS) were analyzed. The results showed that steam pretreatment significantly decreased the hemicellulose and extractives contents of the rice straws. Furthermore, steam pretreatment improved the mechanical properties and water resistance of the rice straw particleboards. [ABSTRACT FROM AUTHOR]