Search Results (215)

Aluminum matrix composites provide an ideal solution for lightweight brake disks, but conventional casting processes are prone to crack initiation due to inhomogeneous reinforcement dispersion, gas porosity, and inadequate toughness. To break the conventional trade-off between high wear resistance and low toughness of brake disks, this study fabricated a bimetallic structure of SiC_p/Al–Fe–V–Si aluminum matrix composite and cast ZL101 alloy using friction stir lap welding (FSLW). Then, the microstructural evolution, mechanical properties, and tribological behavior of the FSLW joints were studied by XRD, SEM, TEM, tensile testing, and tribological tests. The results showed that the FSLW process homogenized the distribution of SiC particle reinforcements in the SiC_p/Al–Fe–V–Si composites. The Al₁₂(Fe,V)₃Si heat-resistant phase was not decomposed or coarsened, and the mechanical properties were maintained. The FSLW process refined the grains of the ZL101 aluminum alloy through recrystallization and fragmented eutectic silicon, improving elongation to 22%. A metallurgical bond formed at the joint interface. Tensile fracture occurred within the ZL101 matrix, demonstrating that the interfacial bond strength exceeded the alloy’s load-bearing capacity. In addition, the composites exhibited significantly enhanced wear resistance after FSLW, with their wear rate reduced by approximately 40% compared to the as-received materials, which was attributed to the homogenized SiC particle distribution and the activation of an oxidative wear mechanism. Full article

4,4’-Methylenebis(N,N-diglycidylaniline) (AG80), as a high-performance thermosetting material, holds significant application value due to the enhancement of its strength, toughness, and thermal stability. However, conventional toughening methods often lead to a decrease in material strength, limiting their application. Modification of AG80 epoxy resin was performed using hydroxy-terminated polyphenylpropylsiloxane (Z-6018) and a self-synthesized epoxy compatibilizer (P/E30) to regulate the phase structure of the modified resin, achieving a synergistic enhancement in both strength and toughness. The modified resin was characterized by Fourier transform infrared analysis (FTIR), proton nuclear magnetic resonance (¹H NMR) spectroscopy, silicon-29 nuclear magnetic resonance (²⁹Si NMR) spectroscopy, and epoxy value titration. It was found that the phase structure of the modified resin significantly affects mechanical properties. Thus, P/E30 was introduced to regulate the phase structure, achieving enhanced toughness and strength. At 20 wt.% P/E30 addition, the tensile strength, impact strength, and fracture toughness increased by 50.89%, 454.79%, and 152.43%, respectively, compared to AG80. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses indicate that P/E30 regulates the silicon-rich spherical phase and interfacial compatibility, establishing a bicontinuous structure within the spherical phase, which is crucial for excellent mechanical properties. Additionally, the introduction of Z-6018 enhances the thermal stability of the resin. Full article

To develop solutions to the frequency instability and failure of silicon micromechanical resonant accelerometers, the state characteristics of micromechanical resonant accelerometers are investigated under temperature and vibration stresses. Through theoretical analysis and finite element simulation, the following is found: the Young’s modulus of silicon varies with temperature, causing a resonance frequency shift of −1.364 Hz/°C; the residual stress of temperature change affects the resonance frequency shift of the microstructure, causing it to be 5.43 Hz/MPa (tensile stress) and −5.25 Hz/MPa (compressive stress); thermal expansion triggers the failure of the bonding wire, and, in the range of 10 °C to 150 °C, the peak stress of the electrode/lead bond area increases from 83.2/85.6 MPa to 1.08/1.28 GPa. The failure mode under vibration stress is resonance structure fracture and interlayer peeling. An isolation frame design is proposed for the sensitive part of the microstructure, which reduces the frequency effects by 34% (tensile stress) and 15% (compressive stress) under temperature-variable residual stresses and the maximum value of the structural root mean square stresses by 69.7% (X-direction), 63.6% (Y-direction), and 71.3% (Z-direction) under vibrational stresses. Full article

Against the backdrop of global energy transition and strict environmental regulations, supercritical carbon dioxide (scCO₂) fracturing and oil displacement technologies have emerged as pivotal green approaches in shale gas exploitation, offering the dual advantages of zero water consumption and carbon sequestration. However, the inherent low viscosity of scCO₂ severely restricts its sand-carrying capacity, fracture propagation efficiency, and oil recovery rate, necessitating the urgent development of high-performance thickeners. The current research on scCO₂ thickeners faces a critical trade-off: traditional fluorinated polymers exhibit excellent philicity CO₂, but suffer from high costs and environmental hazards, while non-fluorinated systems often struggle to balance solubility and thickening performance. The development of new thickeners primarily involves two directions. On one hand, efforts focus on modifying non-fluorinated polymers, driven by environmental protection needs—traditional fluorinated thickeners may cause environmental pollution, and improving non-fluorinated polymers can maintain good thickening performance while reducing environmental impacts. On the other hand, there is a commitment to developing non-noble metal-catalyzed siloxane modification and synthesis processes, aiming to enhance the technical and economic feasibility of scCO₂ thickeners. Compared with noble metal catalysts like platinum, non-noble metal catalysts can reduce production costs, making the synthesis process more economically viable for large-scale industrial applications. These studies are crucial for promoting the practical application of scCO₂ technology in unconventional oil and gas development, including improving fracturing efficiency and oil displacement efficiency, and providing new technical support for the sustainable development of the energy industry. This study innovatively designed an amphiphilic modified amino silicone oil polymer (MA-co-MPEGA-AS) by combining maleic anhydride (MA), methoxy polyethylene glycol acrylate (MPEGA), and amino silicone oil (AS) through a molecular bridge strategy. The synthesis process involved three key steps: radical polymerization of MA and MPEGA, amidation with AS, and in situ network formation. Fourier transform infrared spectroscopy (FT-IR) confirmed the successful introduction of ether-based CO₂-philic groups. Rheological tests conducted under scCO₂ conditions demonstrated a 114-fold increase in viscosity for MA-co-MPEGA-AS. Mechanistic studies revealed that the ether oxygen atoms (Lewis base) in MPEGA formed dipole–quadrupole interactions with CO₂ (Lewis acid), enhancing solubility by 47%. Simultaneously, the self-assembly of siloxane chains into a three-dimensional network suppressed interlayer sliding in scCO₂ and maintained over 90% viscosity retention at 80 °C. This fluorine-free design eliminates the need for platinum-based catalysts and reduces production costs compared to fluorinated polymers. The hierarchical interactions (coordination bonds and hydrogen bonds) within the system provide a novel synthetic paradigm for scCO₂ thickeners. This research lays the foundation for green CO₂-based energy extraction technologies. Full article

To examine the impact of the strain rate on the anisotropic mechanical characteristics of single-crystal silicon, nanoindentation and micro-tensile–compression tests were performed. This study analyzed the effects of varying crystal orientations at different strain rates on load–displacement behavior, elastic modulus, hardness, fracture toughness, and true stress–strain responses. The nanoindentation results showed that at room temperature, single-crystal silicon exhibited an elastic recovery rate of approximately 42%. Notably, the elastic modulus remained unaffected by strain rate variations, whereas hardness increased with higher strain rates. Fracture toughness at room temperature displayed marked anisotropy, with the <100> orientation exhibiting the lowest value at 0.691 MPa·m^1/2 and the <110> orientation showing the highest one at 0.797 MPa·m^1/2. Additionally, tensile and compression experiments revealed that the fracture strength of <100>-oriented silicon increased from 117 MPa at a strain rate of 0.001 s⁻¹ to 550 MPa at a strain rate of 0.01 s⁻¹. Full article

This study investigates the anisotropic fracture behavior of boron-doped p-type single-crystal silicon on the (001) plane, under varying temperatures and crystallographic orientations, utilizing Vickers’ indentation experiments. Measurements performed at 25 °C, 50 °C, and 90 °C, reveal a strong dependence of mechanical properties—such as hardness, fracture toughness (K_1c), and fracture energy—on both temperature and crystallographic orientation. At room temperature, the fracture energy peaks at 7.52 J/m² along the [100] direction, with a minimum of 4.42 J/m² along the [110] direction. As the temperature rises to 90 °C, the fracture energy decreases across all orientations, where values drop to 5.13 J/m² and 3.65 J/m² for the [100] and [110] directions, respectively. In contrast to pure, undoped silicon, the unexpected reduction in fracture energy with increasing temperature is likely due to dislocations pinned by the substitutional boron dopant at elevated temperatures, as well as the weakening of atomic bonds from thermal expansion. This valuable insight is critical for designing silicon-based devices, where understanding the fracture properties at elevated operating temperatures is important for ensuring reliability and performance. Full article

Modern SiC-based materials are of paramount importance in that they serve as wear-resistant and thermal protectors and as next-generation single-photon sources for photonic and quantum solutions. Efforts are underway to identify more efficient methods of manufacturing SiC-based ceramic materials. The objective of this paper is to provide a description of the optimization of sintering SiC–TiC composites by the electroconsolidation method. The influence of titanium carbide content on the physical and mechanical properties of SiC–TiC composites obtained by spark plasma sintering (SPS) at a pressure of 45 MPa was studied. It was found that compared to sintered silicon carbide, the porosity of composites with 40 mol% TiC decreased from ~30% to 0%, the crack resistance increased from 2.9 to 6.1 MPa × m^0.5, and the hardness increased from 2.9 to 21.5 GPa. The influence of sintering temperature and holding time on SiC–TiC composites’ physical and mechanical properties during sintering at a pressure of 45 MP was also investigated. An increase in temperature from 1900 °C to 2000 °C resulted in an approximately 30% rise in the composite hardness. An extension of the time allotted for the sintering process from 30 to 45 min resulted in a decrease in both the fracture toughness and hardness of the material. The utilization of two- and three-dimensional vector spaces of material features was proposed as a novel methodology for the description of manufacturing process optimization. Full article

This review provides the latest insight (2020 to 2025) for composite-based physical activity monitoring sensors. These composite materials are based on carbon-reinforced silicone rubber. These composites feature the use of composite materials, thereby allowing the creation of new generation non-invasive sensors for monitoring of sports activity. These physical sports activities include running, cycling, or swimming. The review describes a brief overview of carbon nanomaterials and silicone rubber-based composites. Then, the prospects of such sensors in terms of mechanical and electrical properties are described. Here, a special focus on electrical properties like resistance change, response time, and gauge factor are reported. Finally, the review reports a brief overview of the industrial uses of these sensors. Some aspects are sports activities like boxing or physical activities like walking, squatting, or running. Lastly, the main aspect of fracture toughness for obtaining high sensor durability is reviewed. Finally, the key challenges in material stability, scalability, and integration of multifunctional aspects of these composite sensors are addressed. Moreover, the future research prospects are described for these composite-based sensors, along with their advantages and limitations. Full article

High-entropy ceramics (HECs) have garnered considerable interest due to their exceptional mechanical properties and high-temperature stability. Nevertheless, their inherent brittleness significantly restricts industrial applications, posing a challenge to improving toughness without compromising hardness. This study investigates the role of SiC whiskers (SiCw) in simultaneously suppressing grain growth and enhancing the toughness of high-entropy (Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)C (HEC) composites, while maintaining high hardness during high-pressure high-temperature (HPHT) sintering. HEC-SiCw composites were fabricated via HPHT (P = 5 GPa, T = 2000 °C), with SiCw contents ranging from 0 to 40 mol%. As the SiCw content increased, the growth of HEC grains was inhibited, and the fracture toughness progressively rose to a peak value (K_IC = 9.4 ± 1.2 MPa·m^1/2), representing an increase of approximately 184% compared to that of pure HEC, while Vickers hardness remained stable at 26 GPa. The enhancement in fracture toughness is attributed to the heterogeneous grain distribution and robust grain boundary strength, which facilitated a synergistic combination of transgranular and intergranular fracture mechanisms. These mechanisms induced crack deflection and whisker pull-out, effectively dissipating fracture energy and impeding crack propagation, thereby enhancing toughness. This study presents a novel approach to simultaneously refine grain size and improve toughness in HECs through HPHT processing, providing valuable insights for the development of next-generation ceramic composites. Full article

The objective of this study was to measure and compare the mechanical properties of conventional and three additively manufactured soft tissue silicone materials, while evaluating the precision of additively manufactured (AMed) materials through different printing angles. Three additively manufactured soft tissue silicone materials were used, in addition to one conventional self-curing injectable silicone material as a control. AMed materials were divided into three groups with three build angles. Mechanical testing was conducted for tensile and compressive strength by a universal testing machine and Shore A hardness by a durometer. Accuracy analysis of additively manufactured materials (n = 20/group) was performed following superimposition and root mean square (RMS) calculation. Statistical differences between the groups were assessed with a one-way analysis of variance (ANOVA) and Tukey’s post hoc test at a significance level of p < 0.05. Scanning Electron Microscopy (SEM) analysis was performed for fracture surface analyses. The tensile strength of all additively manufactured silicone soft tissue materials was significantly lower (p < 0.0001) than that of the control material. All additively manufactured soft tissue material groups had significantly higher compressive strengths (p < 0.0001) and Shore A hardness values. Accuracy analysis showed no significant difference between the groups when compared at the same printing angle (0°, 45°, and 90°); however, within each material group, printing at 45° had higher RMS values than specimens printed at an angle of 0° and 90°. The conventional soft tissue material (control) had a significantly higher tensile strength than all the AMed soft tissue materials, whereas the opposite trend was found for flexural strength and shore hardness. When selecting an AMed material for soft tissue casts used during implant restoration fabrication, it is recommended to print the soft tissues at either 0° or 90°. Full article

This research investigates the dynamic mechanical properties of silicon carbide-modified concrete using a ∅ 100 mm large-diameter split Hopkinson pressure bar (SHPB). The effects of silicon carbide content, particle size, and strain rate on dynamic compressive strength, deformation, and energy dissipation characteristics were examined. The results indicate that both ordinary concrete and silicon carbide-modified concrete exhibit significant strain rate effects, with peak stress, impact toughness, and fracture degree progressively increasing as strain rate rises. The peak strain and ultimate strain of ordinary concrete decreased with increasing strain rate, while those of silicon carbide-modified concrete decreased initially before increasing again. At a strain rate of 180 s⁻¹, the concrete fracture morphology showed almost no occurrence of cement paste connecting adjacent aggregates. The addition of silicon carbide directly increased the strength of aggregates at the micron scale, thereby enhancing the concrete’s load-bearing ability under high-velocity impact loads. Therefore, the modifying effect of coarse-fineness high-strength silicon carbide particles on the strength and deformation characteristics of concrete was more evident under high strain rate conditions. Full article

Aluminum matrix composites reinforced with silicon carbide particles (SiCp/Al) are widely used in aerospace fields with excellent properties, such as high specific strength, high specific stiffness, and high thermal conductivity. Due to the heterogeneous structure, its microstructure is one of the determinants of workpiece life, and ultrasonic vibration can improve the surface quality after grinding. Therefore, in this study, ultrasonic vibration-assisted grinding (UVAG) orthogonal tests were designed to study the surface morphology of SiCp/Al and the form of SiC particle removal under different machining parameters based on the SEM observation of the material surface, and to analyze the percentage of different kinds of grinding forces. The results show that the existence of particle fracture force depends on the relative sizes of the maximum undeformed chip thickness and the critical chip thickness. Through surface roughness testing and analysis, the influence of processing parameters on the surface roughness of the material is explored, and it is found that the application of ultrasound reduces the surface roughness of the material, which can be used as a guideline for the surface quality of the grinding process and the optimization of the process parameters. Full article

As the trend towards the densification of integrated circuit (IC) devices continues, the complexity of interfaces involving dissimilar materials and thermo-mechanical interactions has increased. Highly integrated systems in packages now comprise numerous thin layers made from various materials. The interfaces between these different materials represent a vulnerable point in ICs due to imperfect adhesion and stress concentrations caused by mismatches in thermo-mechanical properties such as Young’s modulus, coefficients of thermal expansion (CTE), and hygro-swelling-induced expansion. This study investigates the impact of thermal variations on the fracture behavior of three bi-material interfaces used in semiconductor packaging: epoxy molding compound–silicon (EMC–Si), silicon oxide–polyimide (SiO₂–PI), and PI–EMC. Using double cantilever beam (DCB) tests, we analyzed these interfaces under mode I loading at three temperatures: −20 °C, 23 °C, and 100 °C, under both quasi-static and cyclic loading conditions. This provided a comprehensive analysis of the thermal effects across all temperature ranges in microelectronics. The results show that temperature significantly alters the failure mechanism. For SiO₂–PI, the weakest point shifts from silicon at low temperatures to the interface at higher temperatures due to thermal stress redistribution. Additionally, the fracture energy of the EMC–Si interface was found to be highly temperature-dependent, with values ranging from 0.136 N/mm at low temperatures to 0.38 N/mm at high temperatures. SiO₂–PI’s fracture energy at high temperature was 42% less than that of EMC–Si. The PI–EMC interface exhibited nearly double the crack growth rate compared to EMC–Si. The findings of this study provide valuable insights into the fracture behavior of bi-material interfaces, offering practical applications for improving the reliability and design of semiconductor devices, especially in chip packaging. Full article

Silicon nitride (Si₃N₄) is used for high-speed rotating bearings in machine tools, aircraft, and turbo pumps due to its excellent material properties such as high-temperature strength, hardness, and fracture toughness. Grinding with fixed abrasives enables high shape accuracy and high efficiency in machining brittle materials. However, it is difficult to completely remove surface damage, which limits its use in products requiring a nano surface. These defects also result in reduced reliability and shortened lifespan. Magnetic-assisted polishing (MAP) is a technology that can achieve a fine surface by using a mixture of iron powder and abrasives, but it requires a lot of time due to the low material removal rate (MRR). Therefore, this study developed a hybrid processing technology using a metal-bonded grinding wheel and a slurry with hard abrasives for the high precision of silicon nitride ceramic ball bearings. Experiments were conducted in order to compare and analyze the surface roughness and material removal rate. Through MAP, using a grinding wheel with low grit (#325), high-efficiency machining performance was confirmed with a maximum material removal rate of 1.193 mg/min. In MAP, using a grinding wheel with high grit (#2000), a nano-level surface roughness of 6.5 nm Ra was achieved. Full article

Despite the fact that temperature is an important condition that affects the behavior of material interfaces used in integrated circuits (ICs), such as the case for epoxy molding compound (EMC) and silicon (Si), this has not been thoroughly studied. To fill this gap, the present work aims to examine the fracture of the bi-material interfaces in multilayered semiconductor components and, more specifically, the EMC-Si, through the experimental quasi-static mode I fracture experiments conducted at different temperatures. The experiments were followed by numerical simulations using cohesive zone modeling (CZM) implemented using Abaqus. Simulation results were aimed at matching experimental data using an inverse CZM approach to determine cohesive properties such as initial stiffness and maximum traction. Experimental results revealed temperature-dependent variations in fracture behavior, with low temperature (−20 °C) showing a decrease in stiffness with values around 650 MPa/mm and a maximum tensile strength of 48 MPa; high temperature (100 °C) revealed a maximum traction and stiffness of 120 MPa and 1200 MPa/mm, respectively. A possible explanation for the results obtained at high temperatures is that temperature changes cause a significant redistribution of residual stresses in the sample and at the interfaces, reducing the stiffness at lower temperatures. Full article