본 연구는 SCGPA(Spent Coffee Grounds Pellet Ash)를 활용하여 다양한 혼합비율로 시멘트 복합체를 제작함으로써 SCGPA 의 신규 건설 재료로서의 적용 가능성을 확인하는 것을 목적으로 한다. 강도 시험 결과, 28일 압축강도 36.31 MPa 및 휨강도 12 MPa 를 나타낸 혼합비가 최적 혼합비로 도출되었으며, SCGPA의 시멘트 치환율이 증가함에 따라 복합체의 전반적인 강도 특성이 감소하는 경향성을 발견하였다. SEM 및 XRD 분석 결과, SCGPA는 최대 10%의 적절한 치환율을 적용할 경우 큰 강도의 저하를 일으키지 않고 시멘트 대체재로 기능할 수 있음이 확인되었다. 본 연구 결과를 바탕으로, 고품질의 굵은 골재를 함께 사용하여 콘크리트를 생산할 경 우, 30 MPa 이상의 압축강도를 가진 구조용 콘크리트도 제조할 수 있을 것으로 기대된다.

Iron selenides with high capacity and excellent chemical properties have been considered as outstanding anodes for alkali metal-ion batteries. However, its further development is hindered by sluggish kinetics and fading capacity caused by volume expansion. Herein, a series of FeSe2 nanoparticles (NPs)-encapsulated carbon composites were successfully synthesized by tailoring the amount of Fe species through facile plasma engineering and followed by a simple selenization transformation process. Such a stable structure can effectively mitigate volume changes and accelerate kinetics, leading to excellent electrochemical performance. The optimized electrode ( FeSe2@C2) exhibits outstanding reversible capacity of 853.1 mAh g− 1 after 150 cycles and exceptional rate capacity of 444.9 mAh g− 1 at 5.0 A g− 1 for Li+ storage. In Na+ batteries, it possesses a relatively high capacity of 433.7 mAh g− 1 at 0.1 A g− 1 as well as good cycle stability. The plasma-engineered FeSe2@ C2 composite, which profits from synergistic effect of small FeSe2 NPs and carbon framework with large specific surface area, exhibits remarkable ions/electrons transportation abilities during various kinetic analyses and unveils the energy storage mechanism dominated by surface-mediated capacitive behavior. This novel cost-efficient synthesis strategy might offer valuable guidance for developing transition metal-based composites towards energy storage materials.

Diamond/SiC composites were prepared by vacuum silica vapor-phase infiltration of in situ silicon–carbon reaction, and the thermophysical properties of the composites were modulated by controlling diamond graphitizing. The effects of diamond surface state and vacuum silicon infiltration temperature on diamond graphitization were investigated, and the micromorphology, phase composition, and properties of the composites were observed and characterized. The results show that diamond pretreatment can reduce the probability of graphitizing; when the penetration temperature is greater than 1600 °C, the diamond undergoes a graphitizing phase transition and the micro-morphology presents a lamellar shape. The thermal conductivity, density, and flexural strength of the composites increased and then decreased with the increase of penetration temperature in the experimentally designed range of penetration temperature. The variation of thermal expansion coefficients of composites prepared with different penetration temperatures ranged from 0.8 to 3.0 ppm/K when the temperature was between 50 and 400 °C.

Aluminum-based composites are in high demand in industrial fields due to their light weight, high electrical conductivity, and corrosion resistance. Due to its unique advantages for composite fabrication, powder metallurgy is a crucial player in meeting this demand. However, the size and weight fraction of the reinforcement significantly influence the components' quality and performance. Understanding the correlation of these variables is crucial for building high-quality components. This study, therefore, investigated the correlations among various parameters—namely, milling time, reinforcement ratio, and size—that affect the composite’s physical and mechanical properties. An artificial neural network model was developed and showed the ability to correlate the processing parameters with the density, hardness, and tensile strength of Al2024-B4C composites. The predicted index of relative importance suggests that the milling time has the most substantial effect on fabricated components. This practical insight can be directly applied in the fabrication of high-quality Al2024-B4C composites.

The mechanical performance of SiC/SiC composites is significantly influenced by the architecture of fiber reinforcement. Among the various fabrication methods, the nano-powder infiltration transition/eutectic (NITE) process is a promising technique that is capable of achieving a dense and stoichiometric SiC matrix. The reinforcement architecture, such as cross-ply (CP) or woven prepreg (WP), is determined during the preform stage of the NITE process, which is crucial in determining the mechanical properties of SiC/SiC composites. In this study, the tensile test and double notch shear (DNS) test were conducted using NITE-SiC/SiC composites to investigate the effect of the fiber reinforcing architecture on the fracture mechanism of SiC/SiC composites. The tensile strength and maximum shear strength of both CP and WP specimens were nearly identical. However, other mechanical properties, particularly those of CP specimens, exhibited significant variability. A comparison of fracture surfaces and load-displacement curve analyses from the DNS tests revealed that the cross points of the longitudinal or transverse fibers act as obstacles to both deformation and crack propagation. These obstacles were found to be more densely distributed in WP specimens than in CP specimens. The variability observed in the mechanical properties of CP specimens is likely due to size effects caused by the sparser distribution of these obstacles compared to the WP specimens.

본 논문에서는 일치 추적 분해를 활용한 샌드위치 복합재의 결함 탐지 및 정량화 방법을 소개한다. 샌드위치 복합재 시편을 제작하 기 위해 핸드 레이-업 공법과 핫 프레스 공법을 활용하여 결함이 존재하는 시편과 없는 시편을 제작하였다. 결함의 위치와 정도를 파 악하기 위해 플래시 서모그래피를 활용하여 확인하였다. 각각의 시편에서 데이터를 확보하기 위해 pitch-catch법을 활용한 초음파 전 파 실험을 설정하였고, 샌드위치 복합재의 표면에 부착한 압전 센서를 통해 데이터를 확보하였다. 획득한 신호는 일치 추적 분해를 이 용하여 추정 및 분해하고, 고속 푸리에 변환과 웨이블릿 변환 기반 노이즈 제거 방법과의 성능을 비교하였다. 노이즈를 제거한 신호는 각각 동일한 구조의 1-D CNN 모델에 훈련하여 성능을 비교하였다. 제안한 일치 추적 분해 기반 신호 노이즈 제거는 기존의 방법보다 높은 정확도, 안정성, 훈련 속도를 보였으며, 시간-주파수 영역에서 보다 직관적인 모드 분리를 확인하여 특성 추출을 통한 일치 추적 분해 기반 신호 전처리 및 딥러닝 모델 훈련의 가능성을 확장할 수 있음을 확인하였다.

탄소중립을 달성하기 위해 이산화탄소를 포집, 활용, 저장하는 CCUS (carbon capture, utilization, and storage) 기 술이 주목받고 있다. 본 연구에서는 광물 탄산화 공정을 통해 이산화탄소를 탄산염으로 고정하고, 이를 전이금속 탄산염 기반 리튬이온배터리 (LIB) 음극재로 적용하였다. CO2를 탄산염으로 고정후, 이를 이용해 FeCO3를 제작하고, rGO와 PVP와 복합 화하여 음극활물질에 적용하였다. rGO는 전기전도도를 높이고 입자의 응집을 방지해 부피 팽창을 완화했으며, PVP는 계면 활성제로서 입자 표면을 안정화하여 구조적 안정성을 강화하였다. FeCO3-PVP-rGO 복합체 기반한 음극재에 대한 전기화학 테스트를 진행한 결과, FeCO3/rGO 복합체는 1,620 mA/g의 전류 밀도에서 50 사이클 이후에도 400 mAh/g의 용량을 유지하 였다. 본 연구는 CO2를 고부가가치 배터리 소재로 전환하여 차세대 에너지 저장 기술에 기여할 가능성을 시사한다.

Efforts have been extensively undertaken to tackle overheating problems in advanced electronic devices characterized by high performance and integration levels. Thermal interface materials (TIMs) play a crucial role in connecting heat sources to heat sinks, facilitating efficient heat dissipation and thermal management. On the other hand, increasing the content of TIMs for high thermal conductivity often poses challenges such as poor dispersion and undesired heat flow pathways. This study aims to enhance the through-plane heat dissipation via the magnetic alignment of a hybrid filler system consisting of exfoliated graphite (EG) and boron nitride (BN). The EG acts as a distributed scaffold in the polymer matrix, while the BN component of the hybrid offers high thermal conductivity. Moreover, the magnetic alignment technique promotes unidirectional heat transfer pathways. The hybrid exhibited an impressive thermal conductivity of 1.44 W m− 1 K− 1 at filler contents of 30 wt. %, offering improved thermal management for advanced electronic devices.

As the demand for electric vehicles increases, the stability of batteries has become one of the most significant issues. The battery housing, which protects the battery from external stimuli such as vibration, shock, and heat, is the crucial element in resolving safety problems. Conventional metal battery housings are being converted into polymer composites due to their lightweight and improved corrosion resistance to moisture. The transition to polymer composites requires high mechanical strength, electrical insulation, and thermal stability. In this paper, we proposes a high-strength nanocomposite made by infiltrating epoxy into a 3D aligned h-BN structure. The developed 3D aligned h-BN/epoxy composite not only exhibits a high compressive strength (108 MPa) but also demonstrates excellent electrical insulation and thermal stability, with a stable electrical resistivity at 200 °C and a low thermal expansion coefficient (11.46×ppm/°C), respectively.

Carbon foam composites containing hollow microspheres, reinforced by carbon nanotubes (CNTs) and montmorillonite (MMT), have been developed as the thermal insulation and EMI shielding layer. The effects of additive amounts of CNTs/ MMT on microstructure and properties of the carbon foam composites were investigated. Results showed that carbon foam composites had hierarchical porous structure, with CNTs and MMT being relatively uniformly dispersed in the composites. The addition of multiscale additives improved the mechanical, electromagnetic shielding effectiveness and thermal insulation properties of carbon foam composites. The composites containing 0.2 wt.% CNTs and 5 wt.% MMT, showed outstanding compressive strength, up to 8.54 MPa, increased by 116% to pure carbon foam. Their electromagnetic shielding effectiveness was as high as 65 dB, increased by 75%. Due to the hierarchical porous structure and MMT’s heat barrier effect, carbon foam composites presented remarkable thermal insulation properties. The minimum thermal conductivity was 0.45 W·m−1·K−1 at 800 °C. Their exceptional thermal protection can also be evidenced by ablation resistance under flame at 1000 °C. Therefore, such multifunctional carbon-based composites are ideal for use in thermal protection.

The interface area of the face sheet and core of the sandwich composite is seen as a weakness due to its low de-bonding toughness. To overcome this concern, it is critical to develop a suitable modification strategy to enhance the de-bonding toughness of the face sheet/core interface. In the present study, the corrugated core reinforced sandwich composite was prepared through co-curing and secondary bonding approaches. The MWCNTs reinforced adhesive was induced in the face sheet/core interface in different weight concentrations. The MWCNT-reinforced adhesive was prepared using the sonication technique, and its dispersion was examined using atomic force microscopy (AFM). The three-point bending test revealed that sandwich composite prepared using the co-cure method has higher flexural strength than secondary bonded samples due to better bonding face sheet and corrugated core. Compared with MWCNT-free corrugated core reinforced co-cured sandwich composites (CCSC), the flexural strength of 1 wt.% MWWCNT-induced sandwich composite was increased by 101.28%. The microstructural study showed that secondary bonded samples had extensive fibre breakage at the face plate due to early de-bonding of the face sheet and corrugated core. Furthermore, the free vibrational analysis was performed to evaluate the natural frequency and damping values of the corrugated core reinforced sandwich composite. The modal test results indicated that inducing 1wt.% MWCNTs in the face sheet/core interface had enhanced the natural frequencies of co-cured sandwich composites. The present study provides a suitable method to address the weaker de-bonding toughness concerns of face sheet/core interface region of sandwich structures.

Carbon nanomaterials (CNMs) have been the subject of extensive research for their potential applications in various fields, including photovoltaics and medicine. In recent years, researchers have focused their attention on CNMs as their high electrical conductivity, low cost, and large surface area are promising in replacing traditional platinum-based counter electrodes in dye-sensitized solar cells (DSSC). In addition to their electrical properties, CNMs have also displayed antibacterial activity, making them an attractive option for medical applications. The combination of CNMs with metal oxides to form composite materials represents a promising approach with significant potential in various fields, including energy and biology. Here, we introduce porous carbon nanospheres (PCNS) derived from Cocos nucifera L. and its ZnO composite (PCNS/ZnO) as an alternative material, which opens up new research insights for platinum-free counter electrodes. Bifacial DSSCs produced using PCNS-based counter electrodes achieved power conversion efficiencies (PCE) of 3.98% and 2.02% for front and rear illumination, respectively. However, with PCNS/ZnO composite-based counter electrodes, the efficiency of the device increased significantly, producing approximately 5.18% and 4.26% for front and rear illumination, respectively. Moreover, these CNMs have shown potential as antibacterial agents. Compared to PCNS, PCNS/ZnO composites exhibited slightly superior antibacterial activity against tested bacterial strains, including gram-positive Bacillus cereus (B. cereus) and Staphylococcus aureus (S. aureus), and gram-negative Vibrio harveyi (V. harveyi) and Escherichia coli (E. coli) with MIC values of 125, 250, 125, and 62.5 μg/ml, respectively. It is plausible that the outcomes observed were influenced by the synergistic effects of the composite material.

To reduce production cost and inhibit the aggregation of graphene, graphene oxide and copper nitrate solution were used as raw materials in the paper. Cu particles were introduced to the graphene nanosheets by in-situ chemical reduction method in the hydrazine hydrate and sodium hydroxide solution, and the copper matrix composite reinforced with Cu-doped graphene nanosheets were fabricated by powder metallurgy. The synthesized Cu-doped graphene was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The relative density, hardness, electrical conductivity and tensile strength of the copper matrix composite reinforced with Cudoped graphene were measured as well. The results show that copper ions and graphene oxide can be effectively reduced by hydrazine hydrate simultaneously. Most of oxygen functional groups on the Cu-doped graphene sheets can be removed dramatically, and Cu-doped graphene inhibit the graphene aggregation effectively. Within the experimental range, the copper matrix composites have good comprehensive properties with 0.5 wt% Cu-doped graphene. The tensile strength and hardness are 221 MPa and 81.6 HV, respectively, corresponding to an increase of 23% and 59% compared to that of pure Cu, and the electrical conductivity reaches up to 93.96% IACS. However, excessive addition of Cu-doped graphene is not beneficial for the improvement on the hardness and electrical conductivity of copper matrix composite.

CO2 photocatalytic reduction is a carbon–neutral renewable energy technology. However, this technology is restricted by the low utilization of photocatalytic electrons. Therefore, to improve the separation efficiency of photogenerated carriers and enhance the performance of CO2 photocatalytic reduction. In this paper, g-C3N4/Pd composite with Schottky junction was synthesized by using g-C3N4, a two-dimensional material with unique interfacial effect, as the substrate material in combination with the co-catalyst Pd. The composite of Pd and g-C3N4 was tested to have a strong localized surface plasmon resonance effect (LSPR), which decreased the reaction barriers and improved the electron utilization. The combination of reduced graphene oxide (rGO) created a π–π conjugation effect at the g-C3N4 interface, which shortened the electron migration path and further improved the thermal electron transfer and utilization efficiency. The results show that the g-C3N4/ rGO/Pd (CRP) exhibits the best performance for photocatalytic reduction of CO2, with the yields of 13.57 μmol g− 1 and 2.73 μmol g− 1 for CO and CH4, respectively. Using the in situ infrared test to elucidate the intermediates and the mechanism of g-C3N4/rGO/Pd (CRP) photocatalytic CO2 reduction. This paper provides a new insight into the interface design of photocatalytic materials and the application of co-catalysts.

The pursuit of sustainable and durable cementitious composites has led to a growing interest in alternative materials that can improve mechanical performance while reducing CO2 emissions. Nanomaterials, in particular, offer promising avenues due to their unique properties, including high surface area to volume ratio and increased reactivity. This study investigates the efficacy of Cellulose Nanofibers (CNF) in enhancing the durability of mortar exposed to sulfate attacks and alkali-silica reactions (ASR). Both MgSO4 and Na2SO4 solutions were employed to simulate sulfate attacks, while the role of CNF in mitigating ASR was also evaluated. Results indicate that CNF incorporation positively impacts the resistance of mortar against sulfate attacks and ASR, paving the way for eco-friendly and durable cement-based structures with extended service life.