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Low-cost amorphous nano-carbon (ANC) was employed as an absorbent to modify the microwave performance of AlN ceramics (AlN-4 wt% Y 2 O 3 - x wt% C, x = 0, 2.0, 3.8, 3.9, 4.0) via hot-pressing sintering, and the thermal and mechanical properties were also investigated. With the increase of ANC content from 0 to 4.0 wt%, the relative density of AlN composite decreases from 3.28 g cm−3 to 3.16 g cm−3 when sintered at 1800 °C for 2 h, and with the increase of sintering temperature from 1700 °C, the density of the 4.0 wt% ANC doped AlN composite presents trend of increase and reaches the maximum value of 3.16 g cm−3 at 1800 °C and then decreases. The XRD pattern shows that the composites are composed of AlN and Y–Al–O (YAG, YAP, YAM et al.) phases. SEM results indicate that average grain sizes for AlN and secondary phases gradually decrease with increasing carbon content, suggesting inhibited grain growth due to ANC addition. No obvious changes in phase constitution nor intensity changes were detected with the increase in carbon content and sintering temperature. As the carbon content increases from 0 to 4.0 wt%, the dielectric constant gradually increases from ∼9 to 13.89 at 10 GHz, the dielectric loss gradually increases from the vicinity of 10−3 to 0.38 at 10 GHz, and the reflective loss decreases from −27.92 dB to −49.40 dB, the thermal conductivity of the AlN-ANC composite decreases from 116.63 W m−1 K−1 to 50.13 W m−1 K−1. In addition, with 4.0 wt% ANC addition, the dielectric constant, dielectric loss, reflective loss, hardness, elastic modulus, bending strength, and fracture toughness are 13.89, 0.38, 49.40 dB, 6.4 ± 0.4 GPa, 262 GPa, 268.78 MPa, and 1.4 ± 0.1 MPa m1/2, respectively. Its ability to efficiently absorb microwave energy enhances the performance of devices including radar systems, communication equipment, and microwave heating systems, making it a promising candidate for microwave vacuum electronic applications. [ABSTRACT FROM AUTHOR]

Addressing the issue of carbon contamination during the smelting of specialty metals or alloys, utilizing graphite crucibles, has attracted considerable research attention, prompting the exploration of novel ceramic crucible materials. AlN ceramic, renowned for their exceptional high-temperature stability and resistance to corrosion, have emerged as promising candidates to mitigate this concern. Nonetheless, the limited mechanical properties and thermal shock resistance of AlN curtail its widespread application. In this study, Y 2 Zr 2 O 7 was introduced as an additive to enhance AlN's properties, and AlN-based composite ceramics were fabricated by employing pressureless sintering. The effects of Y 2 Zr 2 O 7 addition (3–10 wt%) on the mechanical properties and thermal shock resistance of the resulting composites were examined. The findings revealed that the incorporation of 5 wt% Y 2 Zr 2 O 7 (AlN-5YZO) led to the highest relative density and a refined grain structure, resulting in superior mechanical properties. Notably, the flexural strength, fracture toughness, and Vickers hardness of AlN-5YZO reached 322 MPa, 3.70 MPa m1/2, and 13.34 GPa, respectively. Furthermore, the presence of crack branching and crack deflection within the composite ceramics impeded crack propagation, effectively augmenting their thermal shock resistance. AlN-5YZO samples exhibited residual strength retention rates of 91.0 %, 84.2 %, and 76.7 % after 10, 20, and 50 thermal shocks between 1000 and 1600 °C, surpassing those of pure AlN. The findings of this study present promising avenues for advancing crucible materials tailored for high-temperature applications. [ABSTRACT FROM AUTHOR]

First-principles computations are used to investigate the structural, stability, mechanical, optical, thermal, and electronic characteristics of perovskite material. A novel RbBa 2 Ti 3 O 10 perovskite material is studied by using the generalized gradient approximation (GGA) suggested by Perdew, Burke, and Ernzerhof (PBE) approach in the CASTEP code. According to findings, the compound structure is tetragonal in nature with a space group of 123 (p4/mmm), a lattice parameter, and a volume. RbBa 2 Ti 3 O 10 exhibits indirect bandgap semiconductor behavior, according to its electronic characteristics. The Kramer-Kroning (KK) relations are used for determining optical properties to observe light-matter interaction. Perovskites' mechanical attributes, including their ductility, compressibility, elastic anisotropy, modulus, and mechanical index, were assessed and assigned. The thermal properties of the compound are examined, including its density, minimum thermal conductivity, melting temperature, and Debye temperature. Our investigation shows that RbBa 2 Ti 3 O 10 has potential use in photocatalytic applications. • The compound structure is tetragonal with a space group of 123 (p4/mmm). • RbBa 2 Ti 3 O 10 exhibits indirect bandgap (1.66 eV) semiconductor behavior. • Perovskites' mechanical attributes, like compressibility, anisotropy, modulus, and mechanical index, were assessed. • The thermal properties are examined, including its minimum thermal conductivity, melting temperature, and Debye temperature. • RbBa 2 Ti 3 O 10 has potential use in photocatalytic applications to separate water for H 2 and O 2 production. [ABSTRACT FROM AUTHOR]

TeO 2 single crystals have been widely used in military and civilian fields as an excellent acousto-optic (AO) material. However, due to its significant thermal expansion anisotropy and poor mechanical properties, there is a considerable risk of cracking, which hinders further applications in the AO field. Here we successfully grew a TeO 2 single crystal doped with 2 % Mn4+ ions (TeO 2 :0.02Mn4+). This single crystal demonstrates excellent characteristics, including lower acoustic attenuation (α) and larger refractive index values. In addition, it also possesses a higher AO figure of merit (M 2) of 832 × 10−15 s3/kg than TeO 2 single crystal (∼793 × 10−15 s3/kg). More importantly, the TeO 2 :0.02Mn4+ single crystal demonstrates low thermal expansion anisotropy within a temperature range of up to 450 °C, indicating a greater practical value. The high AO performance may be attributed to manganese ion doping. The doping of Mn increased the refractive indices by enhancing the electronic polarizability and achieved lower acoustic attenuation by improving mechanical properties. Combining the results of elastic modulus and Raman spectroscopy analysis, it is observed that manganese doping optimizes crystal structure disorder, thus improving the issue of thermal expansion anisotropy. These results indicate that this TeO 2 :0.02Mn4+ single crystal has significant potential in designing and manufacturing AO devices. [ABSTRACT FROM AUTHOR]

Ceramic fibers are an important thermal insulation material that are not only widely used in extreme conditions, but also play an important role in energy conservation and energy efficiency for sustainable development. However, the practical application of conventional ceramic fibers has a high thermal conductivity in high-temperature environments, which hinders their widespread application. Here, a novel lamellar structured porous SiTiOC/C composite ceramic materials was designed and prepared with excellent thermal insulating properties. The unique microstructure endowed the porous SiTiOC/C composite ceramic materials with a high IR refractive index (93.81%) and an ultra-low thermal conductivity (0.0562 W·m−1 K−1 at 600 ℃). In addition, the porous SiTiOC/C composite ceramic materials not only exhibited excellent mechanical properties (4.46 MPa at 800 ℃), but also demonstrated impressive oxidation resistance and thermal stability. In summary, the proposed porous SiTiOC/C composite ceramic materials provide a reference for the development of high-temperature insulation with good mechanical properties. [ABSTRACT FROM AUTHOR]

In this study, a highly dense GdB 6 bulk ceramic material was fabricated using one-step in-situ reaction spark plasma sintering technology. The sample with a relative density of 96.7 % and a purity of 96.9 wt% was successfully obtained by sintering at 1800 °C for 30 min under a uniaxial pressure of 50 MPa. The Vickers hardness, elastic modulus and fracture toughness of the as-obtained GdB 6 bulk ceramics were 18.9 GPa, 209 GPa and 1.6 MPa·m1/2, respectively. The thermal conductivity of GdB 6 at room temperature was 28.68 W·m−1·K−1, 70 % of which was mainly attributed to phonon vibration, while the remaining 30 % to the electrical thermal conductivity. In addition, the as-obtained GdB 6 ceramics showed no phase transformation after heat treatment at a relatively high temperature of 2100 °C for 20 min in Ar atmosphere. The highly covalent octahedral boron framework played a critical role in maintaining the phase stability of the GdB 6 crystal lattice. This suggested that GdB 6 ceramics could be used as potential ultra-high temperature ceramics for aerospace applications and high-power vacuum electronic devices operated at high temperatures. [ABSTRACT FROM AUTHOR]

The 2.5D oxide/oxide composites become attractive for their excellent integrity and mechanical properties. The thermal shock resistance performance of the material is very important in the actual high temperature application. In this work, the evolution of microstructure and mechanical behavior of the 2.5D oxide/oxide composites from thermal shock at different temperatures and cycles was investigated experimentally mainly by optical microscope, X-ray computed tomography and macro-mechanical tests. The thermal shock resistance mechanism of oxide/oxide composites was qualitatively explored. The results showed that cracks propagation was the main manifestation of thermal shock damage in composites. Compared with 2D composites, 2.5D composites exhibited the finite domain effect on crack propagation due to its reinforcement had certain fibers in Z -direction. This directly caused the critical thermal shock temperature difference of the 2.5D composites (∼900 °C) was more than twice that of the 2D oxide/oxide composites (∼400 °C). In addition, the finite domain effect also significantly reduced the damage growth rate of the 2.5D composites from cyclic thermal shock, highlighting its excellent thermal shock damage resistance. [ABSTRACT FROM AUTHOR]

The rapid development of micro-electronics has a growing demand on the heat dissipation performance of devices, especially thermal management materials. However, recent researches focus on the improvement of single ability, such as thermal or mechanical properties. Herein, a strategy that simultaneously improves thermal and mechanical performance of thermal manager material was proposed, which was achieved by preparing Cu-SiC w composites via the co-electrodeposition technology. The influence of electroplating parameters, such as temperature, current density and reinforcement contents, on the microstructure evolution, mechanical and thermal conductivity were investigated systematically. The fabricated SiC w composite displayed excellent shear strength up to 420 MPa, which is resulted from the Orowan strengthening and load transferring. Additionally, the thermal conductivity of 340 W/(m·K) was obtained, owing to the uniform distribution of whiskers and good interface between the Cu matrix and whiskers. Therefore, the presented work provided an effective method for fabricating comprehensive thermal-mechanical properties and homogeneous heat dissipation capacity Cu-SiC w composites and paved the way for the practical application in the field of the connector between the power devices and heat sinks. [ABSTRACT FROM AUTHOR]

Al 2 O 3 /B 2 O 3 powder mixtures prepared at various ratios from 10.7 to 54.1 wt% B 2 O 3 were used to synthesize Al 18 B 4 O 33 powders by solid state calcination at 1300 °C for 1 h. Al 18 B 4 O 33 formation was completed at 44 wt% B 2 O 3 instead of stoichiometric ratio of 13.17 wt% B 2 O 3. In other words, B 2 O 3 -rich liquid phase accelerated Al 18 B 4 O 33 crystallization. Al 18 B 4 O 33 particles were not acicular in shape when first formed, but they were fully acicular for the 44 wt% and the 54.1 wt% B 2 O 3 mixtures. Anorthite-based glass and CaO were selected to induce liquid phase sintering. CaO considerably improved densification to 95.4 % relative density at 1350 °C. Both glass and mullite also enhanced densification to 94.8 %. Epitaxial nucleation of mullite on Al 18 B 4 O 33 particles resulted in a solid solution as well. Dielectric, mechanical and thermal properties of the samples were investigated and evaluated for possible applications. [ABSTRACT FROM AUTHOR]

The mechanical and thermal properties of ZrC x are strongly dependent on the composition and microstructure. In the present study, densified ZrC x (x = 0.5, 0.7 and 1.0) with relative density in the range of 99.2–99.7% have been prepared by a combination of spark plasma sintering (SPS) and vacuum arc melting (VAM). Both the Young's modulus and Vickers hardness monotonically increase with increasing C/Zr ratio. The maximum Young's modulus and Vickers hardness values of 488.1 ± 13.4 GPa and 28.8 ± 1.7 GPa, respectively, for dense ZrC have been obtained. With increasing the C/Zr ratio, the thermal conductivity of ZrC x increases. The thermal conductivity ZrC ranged from 25.17 W/m/K to 43.85 W/m/K from ambient to 1200 °C. Owing to the higher density of ZrC x , the present thermal conductivities and Young's modulus of ZrC x are higher than those of the previous studies. The present results are beneficial to design and preparation of ZrC x ceramics. [ABSTRACT FROM AUTHOR]

In this study, we designed four groups of A-substituted medium-entropy perovskites, synthesized (Ba 0.4 Sr 0.4 Ca 0.1 La 0.1)ZrO 3 , a non-equimolar medium-entropy perovskite, and studied its microstructural uniformity. The medium entropy of these perovskites imparts unique mechanical and thermal properties. Compared to pure BaZrO 3 , the cold moduli of rupture of the four samples improved by 164.29%, 121.22%, 91.49%, and 81.87%, respectively, and the relative density increased from 69.47% to over 90%. The thermal conductivities of these materials were lower than those of conventional low-thermal-conductivity perovskite materials, with a minimum value of 1.513 W/(m·K). The high strengths and low thermal conductivities of these novel perovskite materials could provide vast opportunities for various future applications. [ABSTRACT FROM AUTHOR]

Novel high-entropy (TiTaNbZrMo X)(CN) (x = 0, 5, 10, 15, and 20 at%) carbonitride ceramics were synthesised using the carbothermal reduction-nitridation and spark plasma sintering methods. The effects of Mo doping on the microstructure, mechanical properties, and thermal characteristics of these high-entropy ceramics were investigated. The increase in Mo contents caused increased grain size, uniform distribution of elements, improved Vickers hardness and fracture toughness, and reduced thermal conductivity at the same temperature. High-entropy (TiTaNbZrMo 0.2)(CN) ceramic displayed superior Vickers hardness of 21.41 GPa and fracture toughness of 4.34 MPa·m1/2, compared with 20.51 GPa and 3.94 MPa·m1/2 for (TiTaNbZr)(CN) ceramic, respectively. Density functional theory calculations indicated that adding Mo atoms promoted the hybridisation of metal and carbon elements, thereby preferentially enhancing electron filling in the bonding orbital due to high valence electrons. This, in turn, improved the mechanical properties of (TiTaNbZrMo x)(CN) ceramics. Additionally, the increased Mo contents strengthened covalent bonding and induced lattice distortion, reducing the thermal conductivity of high-entropy ceramics. [ABSTRACT FROM AUTHOR]

In this study, according to the Dinger model, aqueous Si 3 N 4 slurries with a solid loading of 63 vol% and a viscosity lower than 1.0 Pa s were successfully prepared using two-grade Si 3 N 4 powders with D 50 = 7.2 μm and 9.4 μm as starting materials. These resulting slurries exhibited good rheological properties and suspension stability. Notably, the presence of β-Si 3 N 4 seeds existed in the starting materials effectively reduced the nucleation barrier by transforming homogeneous nucleation into heterogeneous nucleation. Consequently, it facilitated the reconstructive phase transformation of α-Si 3 N 4 to β-Si 3 N 4 , promoted the anisotropic growth of β-Si 3 N 4 nucleation, and resulted in the final formation of the bimodal microstructure. This unique microstructure significantly enhanced the mechanical properties of Si 3 N 4 ceramics, resulting in a high flexural strength of 1011.4 MPa and a fracture toughness of 14.8 MPa m1/2. These excellent properties were achieved through the combination of gelcasting and gas pressure sintering. Simultaneously, the Si 3 N 4 ceramics exhibited a low thermal conductivity of 47.7 W m−1 K−1, mainly owing to the low density of 95.3 %, the presence of low-thermal-conductivity silicate-based noncrystalline substances, and the possible existence of lattice oxygen in Si 3 N 4 crystals. [ABSTRACT FROM AUTHOR]

Polycrystalline diamond compact (PDC) with different grain sizes were fabricated and the multi-physical behaviors, including mechanical-, thermal-, and magnetic performances, and the microscopic features were examined to study the grain size dependence of wear behavior while cutting dense granite. The results showed that the coarse grade PDC had higher impact resistance and fracture toughness. However, the fine grade PDC had higher cobalt content, hardness and thermal resistance. Among these properties, the wear resistance changed the same way as thermal expansion properties proving the strong correlation. Moreover, the crack network caused by thermal mismatch, and the peeling/fracture of metallic phases and diamond promoted fracture wear and played the critical roles in the wear of coarse grade PDC. [ABSTRACT FROM AUTHOR]

To investigate the mechanism of the influence of the sintering additive ratio on the microstructure evolution of silicon nitride (Si 3 N 4) ceramics, Si 3 N 4 ceramics were prepared by gas pressure sintering using different ratios of Y 2 O 3 /MgSiN 2 as additives. Varying the ratio of Y 2 O 3 /MgSiN 2 changed the composition of the liquid phase, thereby affecting the densification process and phase transformation rate of Si 3 N 4 ceramics, and ultimately changing their microstructure. The reduction in the Y 2 O 3 /MgSiN 2 ratio raised the N/O and Si/O ratios in the system, which increased the liquid phase viscosity. The Si 3 N 4 grain distribution varied from "normal to bimodal". In the case of increasing the proportion of MgSiN 2 and prolonging the sintering time, more of the glass phase evaporated, which reduced the content of the low thermal conductivity phase and increased the continuity of Si 3 N 4 /Si 3 N 4. Therefore, Si 3 N 4 ceramics with 1 wt% Y 2 O 3 and 5 wt% MgSiN 2 exhibited excellent properties after sintering at 1900 °C for 12 h, with thermal conductivity, bending strength, and fracture toughness of 106.7 Wm−1K−1, 776 MPa, and 11.66 MPa m1/2, respectively. [ABSTRACT FROM AUTHOR]

Magnesium aluminate (MA) spinel has shown potential as a refractory material under harsh environments, such as high temperatures and frequent temperature variations. However, understanding the mechanical and thermal properties of MA spinel is a key step towards further improvement of MA spinel refractory materials in high-temperature fields. The formation of solid solution represents a prominent strategy to improve mechanical and thermal properties. The present study develops novel (1- x)MgAl 2 O 4 - x Mg 2 TiO 4 (0≤ x ≤ 0.1) solid solutions by single-step reaction sintering method using light-burned magnesia, reactive alumina, and as-prepared Mg 2 TiO 4 (M 2 T) powders. The effects of M 2 T content on the crystal structure, mechanical properties, and thermal properties of the MgAl 2 O 4 -Mg 2 TiO 4 solid solutions (MATss) were studied. Based on XRD, TEM, and HRTEM results, MATss were highly crystallized with a cubic spinel structure. Besides, the M 2 T addition facilitated the flexural strength, hardness, and elastic modulus in the MA spinel. Among these solid solutions, the x = 0.08 sample exhibited the highest flexural strength, hardness, and elastic modulus of 219.47 MPa, 19.99 GPa, and 270.2 GPa, respectively. M 2 T additive played a solid-solution strengthening role, which enhanced the inherent resistance to microstructural damage. Additionally, the x = 0.08 sample had the highest thermal conductivity and thermal diffusivity of 12.45 W/(m·K) and 7.98 mm2/s, respectively. In comparison with pure MA spinel, the x = 0.08 sample showed a lower thermal expansion coefficient (8.63 × 10-6 K-1 at 1550 °C). These excellent mechanical properties and exceptional thermal behavior enabled its widespread application in refractory materials. [ABSTRACT FROM AUTHOR]

High-performance ceramics with low thermal conductivity, high mechanical properties, and idea thermal expansion coefficients have important applications in fields such as turbine blades and automotive engines. Currently, the thermal conductivity of ceramics has been significantly reduced by local doping/substitution or further high-entropy reconfiguration of the composition, but the mechanical properties, especially the fracture toughness, are insufficient and still need to be improved. In this work, based on the high-entropy titanate pyrochlore, TiO 2 was introduced for composite toughening and the high-entropy (Ho 0.2 Y 0.2 Dy 0.2 Gd 0.2 Eu 0.2) 2 Ti 2 O 7 -xTiO 2 (x = 0, 0.2, 0.4, 1.0 and 2.0) composites with high hardness (16.17 GPa), Young's modulus (289.3 GPa) and fracture toughness (3.612 MPa·m0.5), low thermal conductivity (1.22 W·m−1·K−1), and thermal expansion coefficients close to the substrate material (9.5 ×10−6/K) were successfully prepared by the solidification method. The fracture toughness of the composite toughened sample is 2.25 times higher than that before toughening, which exceeds most of the current low-thermal conductivity ceramics. • Preparation of high-entropy pyrochlore/TiO 2 composites by rapid melt solidification. • The composite toughened samples have ultrahigh fracture toughness (3.612 MPa·m0.5). • The solidified composites exhibit excellent mechanical and thermal properties. [ABSTRACT FROM AUTHOR]

Carbon-metal carbide composites are a novel family of materials with potential application in heat dissipation due to the lightness and thermal-mechanical properties. Within these composites, those of graphite-chromium carbide have been still few studied. Therefore, this research focuses on both the influence of the powder preparation method (mechanical mixing (MM) and colloidal synthesis (CS)) and the spark plasma sintering (SPS) temperature (1600, 1700, 1800, 1900 and 2000 °C) in the properties of the composite graphite-7 vol. Cr. Results indicate that the composites sintered from powders processed by CS exhibit better properties, which can be explained by the better dispersion of the chromium carbide, formed during the sintering process, in the matrix of composite. Apart from the powder preparation method, sintering temperature has influence on the properties of the composite: 1900 °C is the best in the case of the route CS + SPS, while 2000 °C is the best option in the route MM + SPS. The thermal conductivity in-plane is 1.75 times greater in the CS than in the MM route, which suggests a better performance in the composite processed by colloidal route in heat dissipation applications. [ABSTRACT FROM AUTHOR]

The porous SiC-Mullite porous ceramics with different pore size were prepared by SiC particles, kaolin, Al(OH) 3 , and flake graphite, V 2 O 5 and AlF 3 were used as mineralizers, the pore size was controllable by adjusting the size of flake graphite. Then the improved empirical formula and grey theory were used to study the effect of the change in pore size on the material properties. The results showed that with the increase of mean pore size from 1.1 μm to 8.5 μm, the cold modulus of rupture and cold crushing strength decreased by 20.8 MPa and 13.7 MPa, respectively. And the thermal conductivity increased from 1.213 W⋅m−1⋅K−1 to 1.721 W⋅m−1⋅K−1 at 800 °C. The <5 μm pores were helped enhance the strength and decreased the thermal conductivity. [ABSTRACT FROM AUTHOR]

In Part 1 of this study, we investigated the macrokinetic parameters and phase formation mechanism in the combustion front of Zr–Nb–B mixtures. In the second part, we produced consolidated samples of solid solutions NbB 2 -(0.100%)ZrB 2 by hot pressing the combustion-derived powders at 1900 °C. By measuring the crystallographic parameters, mechanical and thermophysical properties of the produced bulk samples, we obtained valuable insights into the behavior of the solid solutions. Our results pave the way for the application-specific fine-tuning of the mechanical properties and thermal conductivity of diboride solid solutions in the Zr–Nb–B system for ultra-high temperature applications. Our findings have significant implications for the development of advanced materials with outstanding performance in extreme environments. [ABSTRACT FROM AUTHOR]

Reactive Structural Materials (RSMs) are a new class of materials composed of two or more metallic materials with oxide-ceramic particles that are unable to ignite or explode under various types of loadings, such as thermal, mechanical, and electrical. This study aims to investigate the microstructure, thermal, physical and mechanical properties of the Al-Ni composites, as a type of RSMs, produced by mechanical alloying and subsequent hot pressing. In this research, the Al-Ni composites with various molar mass ratios of Al to Ni of 2:1, 1:1, and 1:3 were first produced. After determining the optimum molar mass ratio of Al to Ni concerning mechanical and thermal properties, Al-Ni composites were made by adding different amounts of CuO particles (2, 4, and 6 wt%), and their mechanical and thermal properties were determined. The thermal and mechanical results proved that the 1:1 molar mass ratio of Al to Ni in the Al-Ni composite exhibited optimal properties. The thermal properties of the Al-Ni-CuO composites showed that the general addition of CuO particles had a negative impact on the energy release of the Al-Ni composites. However, the combustion test showed that the presence of a low level of CuO particles (2 wt%) increased the reaction temperature from 1180 °C to 1368 °C. However, the higher content of CuO particles (4 and 6 wt%) reduced the reaction temperature of Al-Ni composites. Similar to the thermal properties, the mechanical tests proved the detrimental influence of CuO particles on the compressive strength and hardness values of Al-Ni composites. In-depth discussions on the affecting factors on the mechanical and thermal properties of the Al-Ni-CuO composites have been provided in this work. [ABSTRACT FROM AUTHOR]

Vanadium carbides (VC 1-x) exhibit stoichiometric flexibility due to the presence of various carbon vacancies, which significantly influence their fundamental physical properties. Despite this, a comprehensive understanding of how carbon vacancies affect the mechanical and thermal properties of vanadium carbides remains elusive. Previous research has primarily focused on stoichiometric VC and has yet to fully explore the impact of carbon vacancies. This study reveals that stoichiometric VC is less stable when compared to ordered substoichiometric VC 1-x and employs first-principles calculations to obtain thermodynamic, mechanical, and transport properties of VC 1-x. The ordered carbon vacancy leads to an increase in the V–V bond density and volume. Due to the anharmonic effect, the ordered carbon vacancy impairs heat capacity and thermal expansion. The hardness and toughness decrease with increasing carbon vacancy concentrations. The Boltzmann transport equation is used to calculate electrical and thermal transport properties, which shows that growing scattering effects reduce thermal transport capacity. The results provide accurate data support for vanadium carbide research and theoretical support for designing ultra-high temperature ceramic materials. [ABSTRACT FROM AUTHOR]

Rare-earth (RE) oxide-doped La 2 (Zr 0.7 Ce 0.3) 2 O 7 (LZC) has attracted great interest in thermal barrier coatings (TBCs) because of its lower thermal conductivity. However, studies on the laws governing the effect of different types of RE oxide doping on the performance of LZC ceramics are limited. Therefore, in this study, different types of RE (Sc, Y, Gd and Eu) doped LZC ceramic bulks have been prepared using solid phase reaction method. The effects of RE doping on the crystal structure, mechanical properties and thermal properties of the LZC ceramics were investigated. The results indicated that all five ceramics exhibited a single pyrochlore phase structure, whereas their lattice constants were reduced after doping, with (La 0.85 Sc 0.15) 2 (Zr 0.7 Ce 0.3) 2 O 7 having the lowest lattice constant. The effect of rare earth doping on the grain growth of LZC was not evident; however, it could significantly improve the hardness of LZC. In addition, doping with all four RE ions significantly reduced the thermal conductivity of the LZC ceramics, and the most significant reduction was observed for Gd3+ doping. [ABSTRACT FROM AUTHOR]

Dy 2 TiO 5 ceramics with small grain size range of 1.5–3 μm were successfully prepared by microwave sintering method. The phase composition, microstructure, thermal expansion, stability, corrosion resistance and neutron absorption properties of Dy 2 TiO 5 ceramics were investigated. The results show that Dy 2 TiO 5 ceramics possess high mechanical properties due to the small grain size, with a microhardness of 12.26 GPa. The addition of Mo significantly reduces the thermal expansion phenomenon of the sample. The oxide film formed on the surface of the Dy 2 TiO 5 ceramic enhances its excellent corrosion resistance. In addition, the Dy 2 TiO 5 ceramic shows excellent neutron absorption with 87.34% neutron absorption and over 94% thermal neutron absorption in 8 cm thick particles. [ABSTRACT FROM AUTHOR]

First principles calculations were conducted on (HfTiWZr)B 2 high entropy diboride (HEB) composition, which indicated a low formation energy and promising mechanical properties. The (HfTiWZr)B 2 HEBs were synthesized from the constituent borides and elemental boron powders via high energy ball milling and spark plasma sintering. X-ray diffraction analyses revealed two main phases for the sintered samples: AlB 2 structured HEB phase and W-rich secondary phase. To investigate the performance of multi-phase microstructures containing a significant percentage of the HEB phase was focused in this study. The highest microhardness, nanohardness, and lowest wear volume loss were obtained for the 10 h milled and 2050 °C sintered sample as 24.34 ± 1.99 GPa, 32.8 ± 1.9 GPa and 1.41 ± 0.07 × 10−4 mm3, respectively. Thermal conductivity measurements revealed that these multi-phase HEBs have low values varied between 15 and 23 W/mK. Thermal gravimetry measurements showed their mass gains below 2% at 1200 °C. [Display omitted] [ABSTRACT FROM AUTHOR]

The porous silicon carbide ceramics with multilevel directional pores were prepared by chemical vapor infiltration (CVI) combined with sacrificial template method. Carbon fiber preform with specific structure was used as template, and silicon carbide was deposited by CVI process. Then, the carbon fiber template was oxidized and removed, so that the porous silicon carbide ceramics were obtained. The influence of deposition time on pore structure, mechanical properties and thermal properties was studied. Compared with the traditional pore-making process, the pores formed by sacrificial template method are more regular, which brings excellent mechanical properties and thermal insulation properties. The porosity and flexural strength of the sample deposited for 72 h can reach 66.00% and 67.52 MPa, respectively, the thermal conductivity can be kept below 1 W/(m·K) from room temperature to 1200 °C. [ABSTRACT FROM AUTHOR]

Good fracture toughness can prolong the service life of thermal barrier coatings under thermomechanical loading. Yttria-stabilised zirconia (YSZ) and other novel thermal barrier coatings have low fracture toughness and are thus prone to spalling failure. High-entropy ceramics can provide coatings with excellent mechanical properties. In this study, (ZrYTaErTi)O composites were prepared via a solid-state reaction method based on the concept of high-entropy ceramics. The high-temperature phase stability and mechanical properties of the material were characterised and analysed by X-ray diffraction (XRD) and microindentation tests. The results showed that (Zr 0.544 Y 0.114 Ta 0.114 Er 0.114 Ti 0.114)O had the best fracture toughness, which is 1.5 times higher than that of YSZ, of the ceramics prepared with different composition ratios. At the same time, the effects of grain size and the introduction of a second phase on the fracture toughness of the composites were analysed. This study provides guidance for future research on improving the mechanical properties of novel thermal barrier coating materials. [ABSTRACT FROM AUTHOR]

It is an established paradigm in the emerging fields of nanoscience, nanotechnology and molecular engineering that a very important domain of fundamental research is associated with carbon-based materials. Ever since the discovery of the first member of the fullerene family (C 60) in 1985, and the subsequent discovery of the other members, fullerenes as a nanoscopic allotrope of carbon with anticipated extensive applications in all areas of nanoscience and nanotechnology (both industrial and medical), materials science and engineering, condensed matter physics and chemistry have occupied a central position in research activities across the globe. Detailed investigations, both experimental and theoretical/computational, into their morphology, mechanical, thermal, chemical, biological, electronic, optical and structural properties have led to the emergence of a well-established and independent science of fullerenes, providing very valuable information both in basic and applied sciences. A comprehensive review of these properties of fullerenes, particularly their applications in the above fields will provide valuable up-to-date and essential background information for engaging in new research in this field and also be able to develop new concepts and applications of these exotic carbon structures. For instance, a recent development is their applications in the emerging field of nanoneuroscience, a field interfacing nanoscience and neuroscience. In this extensive, albeit selective survey, related mainly to the C 60 fullerenes, the processes involving their experimental synthesis, theoretical formulation of their geometrical structures, their mechanical and thermal properties and nanomedical applications have been reviewed and summarized both within the experimental and theoretical/computational domains. Essential theoretical concepts, ranging from discrete atomistic molecular dynamics and molecular mechanics methods to continuum-based methods have been expounded in order to facilitate the pursuance of the reviewed literature and also to aid in the development of further research in this field. [ABSTRACT FROM AUTHOR]

In this study, La 1- x Nd x MgAl 11- x Sc x O 19 (x = 0.1, 0.2, 0.3; abbreviated as LNMAS-1, 2, 3) coatings which are supposed to possess better properties than LaMgAl 11 O 19 (LMA) were plasma-sprayed and their high-temperature performance were comparatively investigated. Results show that addition of Nd3+ and Sc3+ as dopants to LMA endows corresponding coatings with reduced thermal conductivity and enhanced thermal expansion coefficient, while maintaining advantageous phase stability, although still being subjected to amorphization in plasma flame and following crystallization upon high-temperature service. Furthermore, the doping could cause adherence increasing between topcoat/bondcoat, benefiting from improved melting condition, especially in LNMAS-2 and LNMAS-3 coatings, which is related to the specific powder morphology and lowered melting point. During exposure to 1350°C, mechanical performance and structure integrity of doped free-standing LNMAS coatings can be well preserved even after 400 h aging. In thermal cyclic fatigue test, LNMAS-2 and LNMAS-3 coatings undertake thermal cycling lifetime of ∼181 and 191 cycles at 1100°C, respectively, 40% durable than that of LMA coating. These preliminary results suggest that LNMAS-2, 3 might be promising candidates for advanced thermal barrier coating applications. [ABSTRACT FROM AUTHOR]

Nanocrystalline ZrC coated graphite was synthesized in mixed molten salt system, and the effect of different zirconium sources and reaction temperature on its synthesis was studied. The effects of nanocrystalline ZrC coated graphite on the microstructure, thermal shock resistance and cold mechanical properties of low-carbon Al 2 O 3 –C refractories in different atmospheres were studied. The results indicated that nanocrystalline ZrC coated graphite synthesized by Zr powder had a more uniform coating structure than ZrO 2 as a zirconium source, and increasing the reaction temperature was beneficial for the synthesis of ZrC. The sample with nanocrystalline ZrC coated graphite fired in nitrogen atmosphere had better mechanical properties, the cold modulus of rupture was 15.67% and 50.67% higher than that of the samples fired under argon atmosphere and carbon-embedded atmosphere, respectively. Meanwhile, Sialon played a significant role in improving the mechanical properties of the samples after thermal shock. In addition, the treatment in argon or carbon-embedded atmosphere was beneficial in improving the thermal shock resistance of the samples. [ABSTRACT FROM AUTHOR]

Recently, 3D-printed metamaterials have undergone rapid development; however, the preparation of most metamaterials requires the use of resin-based materials. Thus, multifunctional ceramic metamaterials, especially the introduction of other materials to optimize thermal metamaterials, must be investigated. Here, lattice structures with different units were prepared via stereolithography appearance (SLA) process. The SiC-reinforced phase was obtained by applying chemical vapor infiltration (CVI). The effects of the SiC content and unit type on the mechanical and thermal properties were studied. The results showed that the thermal expansion coefficient (CTE) of the structures decreased by 50% after one CVI cycle. Among the structures, the wave-shaped torsion flexible design reduced the instantaneous CTE to 3.67 × 10−6 K−1 at 150 °C, lower than that for the other structures. More importantly, the lattice structures strengthened with SiC whiskers exhibited outstanding mechanical performance. The compressive strengths of the triangular structure after sintering, one cycle of CVI, two cycles of CVI, and the introduction of SiC whiskers after one cycle of CVI were 3.23, 10.51, 27.38, and 39.4 MPa, respectively. The introduction of SiC increased the compressive strength of the structure by nearly 10 times, satisfying the requirements of high strength and low CTE. Thus, this method can considerably improve the thermal and mechanical properties of 3D-printed ceramic metamaterials, laying the foundation for an in-depth study on the design and preparation of thermal metamaterials. [ABSTRACT FROM AUTHOR]

Of large length-to-diameter ratio and specific area, inorganic whiskers were widely applied for polymer reinforcement. As a well-known nanofiller, titanium dioxide (TiO 2) has been welcome by polymer engineering, mostly for whitening with spherical shapes favored. To date, there have been no TiO 2 whiskers reported for polymer reinforcement. In this work, a rutile type TiO 2 whisker was compounded with polyamide 66 (PA66) to prepare nanocomposites with surficial modification being conducted to further improve the compatibility between them. It was found that the rutile-type TiO 2 whisker significantly improves the mechanical properties of PA66 at high loadings and the performance went better when surficial modification for it was applied. Under 50 wt% addition of TiO 2 whisker either modified or not, the tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength and heat deformation temperature of prepared PA66 composites were respectively increased by 52 %, 279 %, 44 %, 313 %, 20 %, 199 % and 84 %, 279 %, 88 %, 303 %, 114 %, 207 %, comparing with the pristine PA66. The mechanism regarding the overall reinforcement was analyzed, which was attributed to the shape-relevant multiple interactions between TiO 2 and PA66. Besides, the improved adhesion due to strong stable chemical bonding by surficial modification of fillers, is also accountable. [Display omitted] [ABSTRACT FROM AUTHOR]

With the increasing demand for highly integrated circuits to optimize energy efficiency, reduce weight, and improve mechanical properties, finding a Magnesium (Mg) matrix material with excellent mechanical strength and high thermal conductivity poses a significant challenge. In this work, titanium (Ti) particles were introduced into AZ91 (Mg-9Al-1Zn) alloy to fabricate Ti/AZ91 composites, employing a combination of stir casting, extrusion and rolling processes. This strategy simultaneously enhances the mechanical properties and thermal conductivity of the Ti/AZ91 composites compared with AZ91 alloy. The incorporation of Ti particles serves to refine grains, expediting the formation of Mg 17 Al 12 phase within the Mg matrix. Optimal comprehensive mechanical properties are attained in 10 wt% Ti/AZ91 composite, exhibiting an ultimate tensile strength of 365 MPa, an elongation of 11.9 %, and a significantly low wear rate of 4.548×10−3 mm3/m. Notably, the 10 wt% Ti/AZ91 composite shows a 41.1 % reduction in wear rate relative to the AZ91 alloy, attributed to the incorporation of hard Ti particles. Furthermore, the thermal conductivity of the 2.5 wt% Ti/AZ91 composite exhibits a significant enhancement over that of the AZ91 alloy. Detailed discussions are provided on the fundamental mechanisms responsible for strengthening, wear resistance, and thermally conductive in Ti/AZ91 composites. These results highlight the substantial potential of Ti/AZ91 composites for lightweight structural applications, such as highly integrated circuits requiring excellent mechanical properties and high thermal conductivity. [Display omitted] • The 10Ti/AZ91 composite demonstrates a remarkable improvement in UTS, EL and wear resistance. • Enhanced mechanical properties results from the deformable Ti particles, refined grains, and weakening of texture. • The Ti/AZ91 composites possess exceptional thermal conductivity while maintaining high strength. [ABSTRACT FROM AUTHOR]

SiC is a promising structural material for future advanced nuclear energy systems. However, the inherent brittleness and difficulty of densification of SiC limits its practical application. In this study, medium entropy alloy (CrCoNi) reinforced silicon carbide composites (CCN/SiC) were sintered at 1950–2200°C by spark plasma sintering (SPS). The influence of CCN addition on the CCN/SiC composites was investigated in terms of microstructure, mechanical and thermal properties. The results show that SiC sintered at 2200℃ has the highest density, and the addition of 7.5 wt% CCN can significantly improve the fracture toughness of SiC. Transgranular fracture, crack deflection, and premature crack termination due to interfacial passivation are considered as potential toughening mechanisms. Although the addition of CCN can degrade the thermal conductivity of SiC ceramics, it has little effect on the structural stability of the SiC matrix at high temperatures. • A dimpled fracture feature was found in the CCN/SiC composites. • The composite exhibits very good structural stability at 1200 °C. • The addition of CrCoNi doubled the fracture toughness of SiC ceramics. [ABSTRACT FROM AUTHOR]

Anionic polyamide 6 (aPA6), synthesized via the ring-opening polymerization of ε-caprolactam, has emerged as a promising matrix for high-performance thermoplastic composites, offering advantages over conventional thermoplastics and thermosets. However, optimizing the microstructure and mechanical properties of aPA6 requires a comprehensive understanding of how processing conditions influence polymerization kinetics and resulting material characteristics. This work systematically investigates the interplay between two critical processing parameters, i.e., the mold temperature and catalysts concentration, on the microstructural and thermomechanical properties of aPA6, via a combined experimental and statistical approach. Increasing the mold temperature from 145 °C to 175 °C and the catalysts concentration led to a reduction in crystallinity, due to the promotion of polymerization over crystallization. Higher temperatures and concentrations also slightly anticipated thermal degradation onset from 388 °C to 327 °C. The elastic modulus decreased from 3.4 GPa to 2.7 GPa as temperature increased, primarily governed by the diminishing crystallinity. Similarly, the ultimate tensile strength declined from 80 MPa to 68 MPa with rising temperature. Interestingly, the strain at break exhibited a complex dependence, peaking at 48 % for an intermediate temperature of 165 °C and lower catalysts concentration, suggesting an optimal balance of crystallinity, branching, and high molecular weight. Statistical empirical models captured these relationships, enabling prediction and tailoring of aPA6 properties by tuning processing conditions. These insights pave the way for optimized manufacturing of high-performance aPA6 composites via techniques like thermoplastic resin transfer molding and expand potential applications to thermally sensitive reinforcements like natural fibers. [Display omitted] • Crystallinity reduced by increasing mold temperature and catalysts. • Elastic modulus peaked at 3.4 GPa with low mold temperatures. • Ultimate tensile strength rised from 68 MPa to 80 MPa with decreasing mold temperature. • Strain at break peaked at 48 % for 165 °C mold temperature and low catalysts concentration. • Statistical models captured property-processing relationships, enabling property tailoring. [ABSTRACT FROM AUTHOR]

Polydimethylsiloxane (PDMS) exhibits exceptional thermal stability and processability, however, limited adhesion and carbonization performance hinders its applications as flexible thermal protection materials. Herein, a phenolic epoxy modified silicone rubber (KFAP@PDMS) was synthesized, and the microscopic morphology, macroscopic mechanical properties, adhesive properties, thermal properties and ablative properties were systematically investigated. Compared to pure PDMS, the modified material exhibits a maximum tensile strength increase of 170 %, maximum elongation at break increases of 141 %, maximum adhesion strength increases of 209 %, and linear ablation rate decrease 84.9 %, respectively. Thermal degradation analysis indicates that the introducing of KFAP increases crosslink density while the degradation products mainly consist of D 3 , D 4 , and toluene compounds. Ablation analysis reveals that the inclusion of KFAP promotes an in-situ carbon-silicon multiphase ceramization reaction, resulting in densification of the carbon layer and significant improvement of the ablation performance. [Display omitted] • A carbon silicon composite hybrid network of phenolic epoxy silicone rubber was constructed. • The adhesion, mechanical and ablation properties of silicone rubber have been simultaneously improved. • Thermal degradation mechanism of hybrid material was discussed in detail. [ABSTRACT FROM AUTHOR]

The inferior mechanical strength and thermal resistance of foam concrete limited its application in thermal insulation engineering. This study focused on enhancing the mechanical strength and thermal resistance of foam concrete by incorporating glass lightweight microspheres (GLM) to partially replace foam. The roles of GLM in foam concrete were investigated through physical, mechanical, and thermal properties tests. The improvement mechanism behind the mechanical strength and thermal resistance was further revealed. Results indicated that the addition of GLM enhanced mechanical strength of foam concrete by promoting hydration reaction, optimizing pore structure, and improving GLM-paste interfaces. The mechanical strength of foam concrete with 20 % GLM increased by about 40 %. Moreover, GLM improved the residual compressive strength after exposure to 800°C, with an enhancement of 39.8 %. The inclusion of GLM reduced the risks of crack formation, densified the paste, and strengthened the foam wall due to its hollow structure, pozzolanic reactivity, melting and filling effects, and the phase transformation of additional C-S-H into well-packed wollastonite. Additionally, GLM with closed and isolated pores reduced the drying shrinkage and water absorption rate of foam concrete. The finding suggests that incorporating an appropriate amount of GLM can produce high-strength, low-density, and thermal-resistant foam concrete. • Using GLM to partially replace foam improved the performance of foam concrete. • Foam concrete with GLM had high strength of 23.6 MPa and density of 1100 kg/m3. • The introduction of GLM contributed to superior high-temperature resistance. • GLM improved pore structure, foam distribution, and pore wall of foam concrete. [ABSTRACT FROM AUTHOR]

• Flexible and ultralight block-copolymerized PIAs were prepared by copolymerization modification. • PIA exhibits outstanding mechanical properties and excellent thermal protection ability. • The tensile strengths of P 1 B 3 –PIA and P 0 B 1 –PIA are as high as 17.633 MPa and 12.852 MPa, respectively. • PIA has an ultra-low thermal conductivity of 15.1 mW·m−1 K−1 and a low drying shrinkage of 4.323 %. Polyimide aerogels (PIAs) have garnered considerable attention for thermal protection owing to their outstanding high-temperature resistance, wide operational-temperature range, and flexibility. However, their flexibility improvement, drying-shrinkage reduction, and thermal-insulation and mechanical-property enhancements still remain research hotspots. Herein, flexible copolymer PIAs were synthesized via copolymerization modification–chemical imidization, which exhibited outstanding mechanical properties, ultralow dry shrinkage, and highly efficient thermal insulation. By taking full advantage of the comonomer 3,3′,4,4′-biphenyltetracarboxylic dianhydride has a rotatable single bond and increases a high free volume of the involved chain, the PIAs achieves a notable transition from brittleness to high flexibility. Results demonstrate that the 5 %-weight-loss temperature of the PIAs is up to 512.6 °C in air and that their thermal conductivity is as low as 15.1 mW·m−1 K−1. Concurrently, the interactions among the involved nanochain segments contribute to the formation of a three-dimensional network structure with high nodal connectivity and robust crosslinking, enhancing the PIA mechanical strength, with the tensile strength and modulus being 17.633 and 468.41 MPa, respectively. Further, the synthesized PIAs exhibit a low density of 0.079 g/cm3 and low drying shrinkage of 4.323 %. Overall, this research introduces a novel method for developing flexible, low-shrinkage polymer materials with excellent thermal insulation and mechanical properties, exhibiting vast potential for application in aerospace exploration efforts. [ABSTRACT FROM AUTHOR]

2,5-furandicarboxylic acid is an extremely appealing renewable chemical building block because of its potential to replace the petrochemical and industrially widespread terephthalic acid via the synthesis of poly(alkylene 2,5-furanoate)s (2,5-PAF). The recent interest in its structural isomer, 2,4-furandicarboxylic acid (2,4-FDCA), opened the study of poly(alkylene 2,4-furanoate)s (2,4-PAF). In this work, 2,4-FDCA was polymerized with linear glycols of increasing chain length, via a solvent-free polycondensation reaction, obtaining high molecular weight 2,4-PAF. Namely, poly(trimethylene 2,4-furanoate) (2,4-PTF), poly(pentamethylene 2,4-furanoate) (2,4-PPeF) and poly(hexamethylene 2,4-furanoate) (2,4-PHF). These polyesters were compression molded into films and subjected to NMR, GPC, WAXS, PLOM, TGA and DSC analyses. The functional properties for food packaging applications were evaluated by mechanical and gas permeability tests. 2,4-PAF had tunable mechanical properties, depending on the glycol used, and in some cases, the mechanical behavior of a thermoplastic elastomer and shape recovery after break. In particular, 2,4-PPeF had outstanding gas barrier properties, while DSC analyses on 2,4-PHF showed an endothermic phenomenon attributed to the isotropization of a partially-ordered phase: it was possible to demonstrate that this phase was disrupted during tensile tests and slowly recovered over time, at room temperature. Overall, the results offer new insights into the structure-property relationships of poly(alkylene 2,4-furanoate)s and display their great potential for the production of biobased, monomaterial, easily recyclable and sustainable food packaging. [Display omitted] • Green synthesis of high molecular weight 2,4-FDCA-based polyesters. • Functional properties suitable for sustainable food packaging. • Isomerism-properties relationship. [ABSTRACT FROM AUTHOR]

Vanadium carbide coated diamonds were successfully fabricated by molten salt method. The effect of temperature (from 700 °C to 1000 °C) and molar ratio (carbon:vanadium, from 7:1 to 1:1) on the mechanical and thermal performance of vanadium carbide coatings and coated diamond particles were systematically investigated by SEM, EDS, XRD and XPS. The results showed that, compared with uncoated diamonds, the static compressive strength and oxidation resistance of the coated diamonds increased by 42.27 % and 158.82 °C, respectively. The vanadium carbide coatings were mainly composed of V 2 C and VC. As the temperature rose, the thickness of the coatings increased and cracks and holes appeared on the surface of the coating under thermal stress. With the increasing of the relative content of vanadium in raw materials, the crystal structure of vanadium carbide coatings changed from microcrystalline structure to reticular structure and the microcrystalline structure vanadium carbide coatings showed better performance. [Display omitted] • Successfully prepared vanadium carbide coated diamonds by molten salt method. • Systematically studied the effect of multiple preparation parameters on the properties of coated diamonds. • The strength and oxidation resistance of vanadium carbide coated diamonds increased by 42.7 % and 158.82 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] In this review paper, different nanocomposites are introduced and their performances considering thermal, mechanical, electrical, and optical properties are evaluated. Nanocomposites are prepared using various techniques with different fillers or reinforcing materials. They are classified into metal-based, polymer-based, carbon-based, and epoxy-based nanocomposites. The optimized concentration of nanofillers or nanoparticles in nanocomposite structure and choosing the proper base material strengthens the performance of nanocomposites. The results show that integrating multi-walled carbon nanotubes (2 wt%) to Cu with thermal conductivity of 390 W/m.K, Polyaniline-photoadduct with an electrical conductivity of 3 × 102 S/cm, Polyaniline-NiFe 2 O 4 with an energy band gap of 1 eV, and nitrogen-alloyed Cr with a maximum hardness of 37 GPa and Young's modulus of 340 GPa can be introduced as best nanocomposites considering their thermal, electrical, optical, and mechanical properties, respectively. The results assist in selecting the appropriate nanocomposite considering their fundamental features for various applications (i.e., fuel cells, photovoltaic-thermal modules, sensors, photocatalysis, aerospace, marine, gas, and oil industries), contributing to a more sustainable and technologically advanced future. [ABSTRACT FROM AUTHOR]

• A novel polymerization-regulated strategy was proposed to realize the preparation of PI aerogel films. • The PI aerogel films exhibited high tensile strength and modulus of 11.7 MPa and 410 MPa, respectively. • The tensile failure process of the aerogel film was simulated by an improved finite element model. • The PI aerogel films possessed highly efficient thermal insulation at −130 to 300 °C. • The PI aerogel films exhibited high strength, high toughness, heat insulation, and high hydrophobicity. The development of flexible and foldable aerogels for thermal protection in harsh environments has been a long-term challenge as high porosity and weak interface connection can result in typical brittleness. Herein, a remarkable polymerization-regulated strategy was proposed to prepare polyimide (PI) aerogel films with high flexibility and efficient thermal insulation in extreme temperatures by using a facile phase-separation (PS-PI films) method. The polymerization degree of monomers was innovatively used to regulate the flexibility and mechanical properties of PS-PI films by slightly regulating the proportion of monomers. The results showed that the PI aerogel film realized the transition from brittleness to high flexibility, and the tensile strength and fracture strain of PS-PI films were increased by 3 times (11.7 MPa) and 4 times (18.7 %), respectively. Besides, a finite element model was established to analyze the tensile deformation process, revealing the destruction mechanism of aerogel film. The prepared PS-PI film also exhibited robust mechanical properties and efficient thermal insulation properties at extreme temperatures (−130 to 300 °C). The developed PS-PI film possessed high flexibility and efficient thermal-insulated performance at extreme temperatures, which could be a potential candidate for thermal protection in aerospace, energy, and buildings. [ABSTRACT FROM AUTHOR]

• Al 2 O 3 modified epoxy-glass fiber composites were successfully prepared and tested. • The composite material with 2 %Al 2 O 3 filler has the best comprehensive mechanical properties. • Thermal conductivity increased by 20%; the specific heat capacity is increased by 30%. • Burning time increased by 10 s. • The mechanical properties of the samples prepared by vacuum diversion process are better. The present study intends to use Al 2 O 3 as thermal conductivity filler, epoxy resin as matrix, and glass fiber as reinforcement material, and prepare Al 2 O 3 modified epoxy-glass fiber composite materials through vacuum diversion flow and hand paste molding. By changing the amount of Al 2 O 3 , performance tests and comparison are conducted. The results show that when the content of Al 2 O 3 filler is 2 %, the comprehensive mechanical properties are the best, the thermal conductivity is increased by about 20 %, the specific heat capacity is increased by about 30 %, and the combustion time is also increased by 10 s. [ABSTRACT FROM AUTHOR]

The mechanical properties of WC-Ni coatings by HVOF thermal spraying were comprehensively evaluated by indentation tests at a wide load range of 10−1-103 N, i.e. nano-, micro- and macro-indentations. The correlation between process parameters and coating microstructure and mechanical properties was characterized via particle deposition temperature. The coating microstructure changes in reduced porosity, enhanced WC phase decomposition and better splats flattening were correlated to the particle deposition temperature rising. A porosity divergence between coating surface and cross-section was found as a quantitative anisotropy indicator to coating intrinsic lamellar microstructure formed by the splats flattening and piling up. Considering the lamellar microstructure, indentation responses on coating surface and cross-section were compared for hardness and elastic modulus evaluation below 3 N. The surface hardness is higher than that of cross-section, and both increased correlatively to the particle deposition temperature rising except for the almost constant surface hardness below 1 N. An analogous particle temperature-dependent behavior was also manifested for the elastic modulus by nano-indentation below 1 N. Interestingly, the elastic modulus by coating surface micro-indentation at 30 N presented identical particle temperature dependence to that by coating cross-section nano-indentation, both consistently representing the overall coating elastic modulus change trend verified by non-destructive ultrasonic test. Indentation fracture toughness on coating surface under 1.96 kN and on coating cross-section under 49 N was comparatively evaluated, and the values had a reverse trend of dependence on the particle deposition temperature. The particle-deposition-temperature dependent mechanical properties were interpreted by the coating intra-splats and inter-splats defects reduction with enhanced carbide-metal bonding essentially determined by the melting state of the metal binder phase, providing an insight to utilize indentation tests for characterizing thermal spray coatings. • WC-12Ni coatings with laminate microstructure are indented in a wide load range. • Surface and cross-section porosity divergence is a quantitative laminate indicator. • Metal binder phase melting state controls intra-splats/inter-splats defects reduction. • Indentation depth effect of hardness and elastic modulus is clarified with laminate. • Microstructure and mechanical properties correlate to particle deposition temperature. [ABSTRACT FROM AUTHOR]

BaAl 2 Si 2 O 8 /BN (BAS/BN) ceramic composites were prepared using hot press sintering. The amorphous state of BAS ceramics exhibits a low melting point, high liquid-phase mobility, and good infiltration with BN grains, facilitating the sintering process. Conversely, the crystalline state of BAS has a high melting point and strength, contributing to the strengthening and toughening of the composite. The mechanical properties, thermal properties and thermal shock resistance of BAS/BN ceramic composite was investigated. Ceramic composites containing 40 vol% BAS have the best overall mechanical properties with bending strength, elastic modulus, fracture toughness, and hardness of 175 ± 3 MPa, 114.0 ± 1.2 GPa, 2.02 ± 0.10 MPa · m1/2, and 1.08 ± 0.01 GPa, respectively. The BAS/BN ceramic composite has excellent thermal shock resistance, and the residual bending strength shows a pattern of increasing and then decreasing with increasing thermal shock temperature difference. Finite element calculation results show that the cooling process is basically completed after 20 s of water quenching, the maximum thermal stress generated is about 22 MPa. [Display omitted] • The mechanical properties and thermal shock resistance of h -BN ceramics are enhanced by the introduction of BAS. • The main phases of BAS/BN ceramic composites are h -BN and h -BaAl 2 Si 2 O 8. • The thermal shock damage mechanism of BAS/BN ceramic composites is elucidated. [ABSTRACT FROM AUTHOR]

In this study, a novel bio-based composite of starch/plant fiber foaming tableware material was prepared by the hot-pressing foaming method. The influence of the content of carboxymethyl cellulos (CMC) as a new type of film-forming agent filler on the properties of foam materials was systematically investigated. The results showed that the foam material with 10 wt% CMC had excellent cell morphology and uniform cell size (the average cell size reached the minimum value of 465.7 μm), relatively high porosity (57.01%), and excellent thermal insulation properties (thermal conductivity: 0.0541 W/m·K). The tensile strength of foam increased from 4.289 MPa for 0 wt% CMC to 5.714 MPa for 10 wt% CMC loading. Similarly, the flexural strength also increased from 11.609 MPa to 15.719 MPa for the foam material with 10 wt% CMC. The thermal stability and viscoelastic properties of the foam material reached the highest after adding 10 wt% CMC. In addition, the increase of CMC content is beneficial to improve the oil resistance and biodegradability of the material. The research shows that CMC is an effective filler to improve the properties of starch/plant fiber foaming tableware materials, which can greatly promote the development of bio-based polymer foam materials. [Display omitted] • Starch/plant fiber foaming tableware material was prepared via a simple hot-pressing foaming method. • CMC was used as film-forming agent to optimize the properties of foam materials. • The addition of an appropriate amount of CMC (10 wt%) makes the cell size smaller and the cell structure more uniform. • CMC can improve the mechanical properties, thermal stability, viscoelasticity and thermal insulation of foam materials. • This new type of foam tableware material can be completely biodegradable under natural conditions within 21 days. [ABSTRACT FROM AUTHOR]

This paper examined the impact of graphene's different scales on carbon fibre-reinforced thermoplastic composites' thermal and mechanical properties (CFRTPs). Experiments using a mixing design method with graphene content of large, medium, and small scales as variables, thermal conductivity (λ) and mechanical properties (flexural (F), compression (C), and tensile strength (T)) as response values. The thermal-mechanical properties of multi-component composites were analyzed and modelled to improve them. Graphene with different scales could effectively bridge and enhance heat flow transfer along the graphene thermal conductivity network, significantly improving the composite's thermal conductivity. It was verified that the optimized composites exhibited excellent thermal conductivity (λ = 1.329 W/m·K), 140.3 % higher than that pure composite. Furthermore, the mechanical properties of the optimized composites saw significant enhancements, with flexural strength, compressive strength, and tensile strength increasing by 18.9 %, 22.8 %, and 13.2 %, respectively. Moreover, the optimized composite's thermal properties and energy storage modulus were also notably improved. [Display omitted] • Synergistic modification of CF/PPBESK composites using graphene at different scales. • Modelling of thermal conductivity and mechanical properties of composites was established. • Theoretical model fits well and predicts accurately. • Thermal conductivity and mechanical properties of composites improved significantly. [ABSTRACT FROM AUTHOR]

With the development of high-density electronics, polymer-based thermal conductive composites with excellent thermal and mechanical performance are receiving great attention. For the development of polymer-based thermal conductive composites with superior properties, it is essential to reduce the agglomeration of fillers and enhance the interfacial interactions between thermal conductive fillers and the polymer matrix. Among the several thermal conductive materials, graphene nanoplatelets (GNPs) and cellulose nanofiber (CNFs) are attracting attention. However, poor interfacial interaction between GNP and CNF leads to interfacial separation, which in turn, deteriorates its properties. Herein, we synthesized a pyranine-functionalized polyether dispersant (PyPE), which can significantly improve the interfacial interactions between GNPs and CNFs. The effect of PyPE on the dispersion behavior of GNPs and the thermomechanical properties of GNP-CNF composite were monitored. Furthermore, we also performed molecular dynamics (MD) simulations to investigate the impact of applying PyPE dispersant on the interfacial interactions between the GNPs and CNF matrix. The application of PyPE significantly enhanced the dispersibility of GNPs within the CNF matrix, resulting in a 15.5 % increase in-plane thermal diffusivity and a 24.5 % enhancement in tensile strength of the composite, demonstrating their potential applications in high power density electrical equipment and electronic devices. [Display omitted] [ABSTRACT FROM AUTHOR]