Microstructure Of Composite Materials Research Articles

Development of Aluminum Alloys 6061(AA6061) Silicon Carbide (SiC)-Graphite (GR) and Hybrid Composite for Automotive Applications

The microstructure and mechanical properties of composite materials made of Silicon carbide (SiC) and Graphite (GR) reinforcement, known as Aluminum Alloy 6061(AA6061) Matrix were developed. Using the stir casting method, the hybrid composites were prepared with 6 weight percent of the reinforcements in the ratio of 0:1,1:3,1:1,3:1,and 1:0. It was determined how the reinforcement particles affected the microstructures and mechanical characteristics of these materials. The microstructure displays a uniformly distributed fine particles of α-Al grains and Mg2Si phase with in the matrix alloy. The microstructure amply demonstrates the presence of the reinforcing particles (SiC and GR) and dendritic development was noted. There are very few indications of particles clusters, and the particles are very dispersed throughout the matrix. Sample A2 (AA6061 25% SiC/ 75% GR) had the highest recorded hardness value of 123.34 HRB4.8,9.33, while the base alloy had the lowest value of 70.36 HRB when compared to the base alloy, the developed hybrid composites showed improved tensile strength. In contrast to the base alloy, which displayed a strength of 115.67N/mm2, Sample A3 demonstrated a maximum strength of 143.88 N/mm2 as compared to the base alloy which showed strength of 115.67 N/mm2. The hard reinforcement particles sharp edges serve as a nucleation site, which is why the strength of samples A4 and A5 decreased when SiC reinforcement is added, the materials extension decreases when the developed hybrid composite materials with samples were compared with the base alloy. In comparison to the created hybrid composite materials, the base alloy displayed a maximum extension of 2.4mm, with sample A5 showing the lowest extension value of 1.23mm. Sample A2 displayed the highest structures rate of 0.060, while sample A5 displayed the lowest strain rate of 0.031. The impact strength values increases from 2.76 (Base alloy) to 4.77j (Sample A5) with the addition of the reinforcement particles. The obtained mechanical properties indicate that the reinforced alloy performed favorably well but not significantly better than the ones in the literature.

Study on mechanical properties of natural fiber (Jute)/synthetic fiber (Glass) reinforced polymer hybrid composite by representative volume element using finite element analysis: A numerical approach and validated by experiment

The excellent mechanical strength with low weight of polymer-based composites makes them superior over conventional materials like steel and aluminum in terms of mechanical properties. Nowadays, researchers are working to develop natural fiber-based sustainable composite. Glass fiber, when combined with jute fiber, could greatly enhance the mechanical characteristics of composites; the sequence of the layers mostly determines these properties. In this study, the hybrid laminate of jute and glass fiber with resin polyester is developed with The representative volume element utilized in ANSYS. In ANSYS material design module, the 3D microstructure of composite material is created with various fiber volume fractions of glass fiber and jute fiber. After that, the effective elastic properties of hybrid jute/glass fiber and polyester as matrix, glass fiber/polyester, and jute fiber/polyester are evaluated and the simulation-based effective elastic property is validated by existing experiment value which showed good agreement. For further study, in Ansys ACP PrepPost, the composite laminate such as hybrid jute + glass fiber/polyester, glass fiber/polyester, and jute fiber/polyester is created with desired lamina thickness, stacking sequence, and fiber orientation. Thereafter, it was transferred to a static structure module to perform tensile and bending test analysis. Ansys ACP post-processing is utilized to investigate stress induced at each lamina of the composite specimen. This study revealed that by adding glass fiber to natural fiber, the mechanical performance is enhanced significantly, whereas hybrid jute + glass fiber/polyester (S2) demonstrated the highest tensile strength 259 MPa compared to other hybrid laminate composites. Astonishingly, The hybrid composite jute + glass/polyester (S2) exhibited 10 % higher bending strength than glass fiber/polyester (S1) and 64 % more than net jute fiber/polyester (S5). Additionally, S2 demonstrated 9.5 % higher shear strength compared to S1 and 64 % more than S5. This study will give a great understanding of how adding glass fiber to jute fiber, could enhance the mechanical properties, which will contribute to the design of an efficient composite part for automotive such as car interiors, car doors, trim panels, lightweight applications, and packaging industries.

Combining thermodynamic modeling and experiments to characterize the effect of ceramic polishing powder in cement-based materials

Ceramic polishing powder (CPP), a by-product of ceramic tile production, has the potential to prepare building materials. While the hydration and thermodynamic properties of CPP remain largely unexplored, thereby limiting its widespread application. This study utilized R3 tests to demonstrate that CPP exhibits pozzolanic activity comparable to that of fly ash. Then it analyzed the effects of substituting 10–20 % of cement with CPP on the hydration products, microstructure, and mechanical properties of composite materials, utilizing a synergistic approach that combines thermodynamic simulations with experimental investigations. The findings showed that adding CPP does not generate new crystalline products but enhances the formation of C-S-H through the pozzolanic reaction, which consumes calcium hydroxide. However, adding over 25 % CPP significantly lowered the pH of the pore solution, altering hydration products and causing volume contraction. In addition, CPP improved the microstructure at later ages, particularly by increasing micropores, leading to enhanced mechanical properties at 28 and 90 days. For instance, at a w/b ratio of 0.5, the 90 days compressive strengths of composite mortars CPP10, CPP15, and CPP20 were recorded at 67.0 MPa, 63.3 MPa, and 65.1 MPa, respectively. These values represented increases of 17.3 %, 10.9 %, and 14.0 % over the control group (57.1 MPa). Conversely, this also resulted in increased autogenous shrinkage due to higher capillary pressure. Notably, the 6 days shrinkage of CPP15 and CPP20 was about 50 % higher compared to that of the pure cement mortar. These findings highlight the necessity of balancing CPP content for optimal performance.

A Low-Carbon Composite Cementitious Material Manufactured by a Combined Process of Red Mud

In present study, the effects of varying dosages of combined red mud on the microstructure and hydration process of low-carbon composite cementitious material. The findings indicated a gradual decrease in the reactivity of RM, following a linear trend. The non-evaporable water content of the composite binder exhibited an initial increase followed by a subsequent decrease, with the optimal content identified at 10%, for RM content ranging from 10% to 90%, non-evaporable water decreases linearly. Optimal bending strength and compressive strength were achieved in the mortar when incorporating 10% of RM, reaching 8.56 MPa and 51.2 MPa at 28 days, respectively. The porosity was at its lowest when the RM content was added at 10%, but further increasing RM dosage was reversed. The pore size distribution aligned with the experimental findings on porosity. X-ray diffraction (XRD) analysis revealed the involvement of RM in the secondary hydration reaction, thereby enhancing the mechanical properties of low-carbon composite cementitious material. The optimal content of RM is suggested to be 10%, with a maximum recommended limit of 30%. The analysis has shown that red mud particles serve a dual purpose in low-carbon composite cementitious material. They enhance compactness by acting as fillers and promote cement hydration through surface activity, thereby enhancing mechanical properties, durability, and pore size distribution.

Inconel 718 alloy reinforced with nano-sized WC particles and graphene nanoplatelets: Microstructure, wear resistance and electrochemical properties

The coarse columnar grain structure of additively manufactured metals diminishes material performance, hence the transition from columnar grains to equiaxed grains is extensively investigated. The microstructure of composite materials and the properties of Inconel 718 are positively influenced by both nano-sized tungsten carbide (nano-WC) and graphene nanoplatelets (GNPs), which act as reinforcing phases. The study employs directed energy deposition (DED) technology for the fabrication of Nano WC/GNPS-IN718 composite materials. Th emicrostructure, wear resistance, and corrosion resistance properties of both Inconel 718 and its composite materials were systemically investigated. The findings discover the microstructure of the composite material consists of γ/M7C3 phases with precipitation of carbides such as (Nb,Ti)C. Utilizing nano WC and graphene as lubricants, and carbides like (Nb,Ti)C as strengthening phases, the composite material exhibits a grain size refinement of approximately 3.36 % compared to IN718. The grain orientation in the XOY plane predominantly aligns along the <001> direction. The Nano WC/GNPS-IN718 composite material exhibited a 1.264-fold increase in average microhardness compared to the IN718 alloy. Notably, the friction coefficient and wear rate were only 77 % and 18.75 %, respectively, of those observed in the IN718 alloy. Furthermore, the corrosion current density of the Nano WC/GNPS-IN718 composite material was 30.8 % of that observed in IN718, with a polarization resistance 4.08 times higher than that of IN718.

Integrated surface microstructure and enhanced dielectric constant for constructing simple, low-cost, and high-performance flexible capacitive pressure sensor

Designing microstructure surface or enhancing the dielectric constant of functional layer is a common useful strategy to improve the pressure sensing performances of flexible capacitive pressure sensors, but it usually involves complex preparation processes (such as artificial microstructure and preparation of composite materials). Considering the limitations of a single strategy in improving the pressure sensing performance of capacitive pressure sensor, herein, we propose a simple strategy that integrates surface microstructure and enhanced dielectric constant of functional layer for constructing a high-performance flexible capacitive pressure sensor. Specifically, the polyester fiber conductive tape and filter paper with intrinsic rough surfaces are selected as microstructure electrodes and dielectric layer, respectively. Meanwhile, by introducing the daily carbon ink into filter paper, the moderate conductivity of the carbon ink is utilized to enhance the dielectric constant of the filter paper dielectric layer. The results show that the proposed the pressure sensor has wide pressure detection range of 0.1−100 kPa, high sensitivity (1.47 kPa−1, 0.1−10 kPa) and good durability (4000 cycles at 20 kPa). Taking the pressure range of 10−100 kPa as an example, the sensitivity of carbon ink paper-based sensor is 60 times higher than that of sensor without carbon ink. The enhanced working mechanism of the sensor is clarified by combining testing and characterization. In addition, the proposed pressure sensor has potential applications in wrist pulse, respiratory rate, walking record, morse code transmission，and stoma bag detection. This work provides a useful reference for constructing simple, low-cost and high-performance flexible capacitive pressure sensor.

Comparative Study of Microstructure and Phase Composition of Amorphous-Nanocrystalline Fe-Based Composite Material Produced by Laser Powder Bed Fusion in Argon and Helium Atmosphere.

Laser powder bed fusion (LPBF) is a prospective and promising technique of additive manufacturing of which there is a growing interest for the development and production of Fe-based bulk metallic glasses and amorphous-nanocrystalline composites. Many factors affect the quality and properties of the resulting material, and these factors are being actively investigated by many researchers, however, the factor of the inert gas atmosphere used in the process remains virtually unexplored for Fe-based metallic glasses and composites at this time. Here, we present the results of producing amorphous-nanocrystalline composites from amorphous Fe-based powder via LPBF using argon and helium atmospheres. The analysis of the microstructures and phase compositions demonstrated that using helium as an inert gas in the LPBF resulted in a nearly three-fold increase in the amorphization degree of the material. Additionally, it had a beneficial impact on phase composition and structure in a heat-affected zone. The received results may help to develop approaches to control and improve the structural-phase state of amorphous-nanocrystalline compositional materials obtained via LPBF.

Production of low-CO2 ternary binder using red sandstone, cement, and granulated blast furnace slag: A comprehensive performance analysis

Red sandstone is rich in reserves, and using it as a mineral admixture to partially replace cement can save cement consumption and reduce carbon dioxide emissions. This study uses spectral characterization, electron microscopy image analysis, mechanical property testing and other methods to study the fluidity, compressive strength, heat of hydration, carbonation degree, microstructure and thermal damage of composite cement-based materials containing red sandstone and slag. The experiment results showed that in ternary mixed cement, the composite cement mixed with 5% slag and 10% red sandstone shows similar flow properties to cement paste. Moreover, as the mineral content (red sandstone and slag) increases, the dissolution peak of the Al phase appears earlier, and the degree of carbonation increases. Furthermore, the CO2 emissions per unit strength gradually decrease. After 28 days of curing, thermal damage experiments demonstrated that the strength of the sample increases by more than 3.6% when the mineral content is greater than 15% at 200℃. Samples were subjected to 600 °C and 900 °C, and the strength of the red sandstone sample with a content of 15% decreased significantly. Moreover, as the temperature increases to (600 °C and 900 °C), the lattice of CnS becomes more and more ordered.

High fidelity FEM based on deep learning for arbitrary composite material structure

Due to the outstanding performance, composite materials are widely used and analyzing their properties and designing them based on performance has become a crucial task in the field of many manufacturing industries. Composite materials possess complex multiscale structures, and traditional fine-scale finite element modeling and analysis may lead to severe computational resource challenges. To overcome this difficulty, breakthroughs in key technologies of multiscale accelerated analysis algorithms are required. In this study, an innovative approach based on artificial intelligence and multiscale finite element method is presented. This approach involves partitioning the entire composite material structure into coarse grids that resemble homogenous structures of similar size, providing results consistent to fine-grid finite element analysis. By utilizing CNN for image feature recognition and employing the CGAN adversarial method, coarse-grid equivalent stiffness matrices and multiscale shape functions from completely random microstructures of composite materials can be obtained. Consequently, this enables a rapid response process from microstructure to low-resolution grid to high-resolution physical field, with remarkably accurate physical field results. Moreover, compared to traditional fine-grid finite element methods, this approach significantly reduces memory usage and computation time. This method is applicable to composite materials with varying shaped inclusions, different component properties, and diverse geometric distributions, allowing these materials to perform high-fidelity finite element calculations on coarse grids and predict their mechanical behavior. Furthermore, this breakthrough opens avenues for accelerating the optimization design of composite materials with diverse mechanical functionalities, by employing a bottom-up approach.

Preparation and Characterization of Bismaleimide-Resin-Based Composite Materials.

This study utilized bismaleimide (BMI) resin, reinforced with introduced ether bonds, as a binding matrix, in combination with silicon carbide (SiC), for the fabrication of composite materials. A thorough investigation was conducted to assess the influence of diverse processing parameters on the mechanical properties and high-temperature thermo-oxidative stability of these composites. Experimental results indicate a notable improvement in the mechanical properties of the composites upon the incorporation of ether bonds, in contrast to their unmodified counterparts. The variation in performance among composites with different ratios and molding densities is apparent. Within a certain range, an increase in resin content and molding density is correlated with improved bending strength in the composites. With a resin content of 27.5 vol% and a molding density of 2.31 g/cm3, the composite achieved a maximum flexural strength of 109.52 MPa, representing a 24% increase compared to its pre-modification state. Even after exposure to high-temperature heat treatment, the composites displayed commendable mechanical properties compared to their pre-ether bond modification counterparts, maintaining 74.5% of the strength of the untreated composites at 300 °C. The scanning electron microscopy (SEM) microstructures of composite materials correlate remarkably well with their mechanical properties.

A node graph using SEM images for material properties prediction with a case study of composite material

Establishing a mapping model between the microstructure and material properties of composite materials is crucial for material development. Scanning electron microscope (SEM) images are widely used for the prediction of material properties. However, the prediction from a single SEM image is independent and does not fully reflect the microstructure characteristics. To address this issue, this paper proposes a node graph construction strategy for SEM images and establishes a multi-graph-based graph attention network (GAT) material property prediction model to achieve the convergence of mutual complementation in microstructure features by using GAT. Firstly, multiple SEM images are constructed into node graphs by a microstructure feature encoder. Next, the microstructure features of multiple SEM images on the node graphs are mutually complemented and converged by using GAT. Finally, the prediction is carried out by using multiple SEM images. The experimental results show that the proposed method shows better performance than other methods.

Micro-reinforced polymer composite materials studied by correlative X-ray imaging

Three-dimensional insights into the microstructure of composite materials are vital for enhancing their performance under operational conditions. Phase-sensitive methods can offer supplementary data, especially for materials with low absorption, compared to standard absorption-based techniques. This work presents the correlative X-ray imaging and computed tomography results of polymer composites reinforced with glass fibers using an inverted Hartmann mask. This method identified areas with enhanced refraction and scattering due to glass fibers and discriminated signals based on their orientation, offering an advantage in evaluating anisotropic materials. The simplicity of the setup, adding the inverted Hartmann mask, makes integration feasible in commercial CT scanners and existing radiography laboratories, enabling simultaneous phase, scattering, and absorption information extraction. Our approach, which combines refraction and scattering with absorption signals, exposes intricate structures beyond the usual spatial resolution threshold. Despite the distinct absorption coefficients of air, polymer-based, and glass fibers, the inverted Hartmann mask is crucial for examining similar absorption composites and low-absorbing materials. This research offers profound insights into the microstructures of fiber-reinforced polymer composites, laying the groundwork for studies of nanostructured functional composite materials.

Production and assessment of UV-cured resin coated stearyl alcohol/expanded graphite as novel shape-stable composite phase change material for thermal energy storage

Expanded graphite-phase change materials (PCM) structures are reinforced to polymers with various methods to fabricate advanced thermal energy storage materials. However, these methods still suffer from processing time and product efficiency challenges. In this study, the UV-curing method was used to produce shape-stable EG-PCM-reinforced resin composites with fast curing and low process temperature of the resin. The composite material, comprising UV-curable resin (30 %), stearyl alcohol (65 %), and Expanded graphite (5 %), was synthesized. This synthesis aimed to address the limitations of traditional PCMs, such as low thermal conductivity and leakage. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to characterize the materials' phase change behavior and thermal stability. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) analyses were conducted to elucidate the microstructure and crystallinity of composite materials. The composites, exhibiting near-perfect impermeability with leakage as minimal as 0.89 %, not only enable the attainment of cooler environments by 2–3 °C under hot air conditions but also demonstrate exceptional thermal stability up to 207 °C, as evidenced by TGA results. Additionally, they offer a remarkable melting enthalpy value of 153.1 J/g. These composites, with their shape-retention ability during phase transitions and high thermal energy storage capacity, are a versatile and efficient option for sustainable energy management. This research contributes to the development of innovative materials for renewable energy integration and reducing carbon emissions.

Dual-modified LiNi0.8Co0.1Mn0.1O2 cathode materials with lithium conducting hybrid oligomer and single-walled carbon nanotube for improving electrochemical performance and thermal stability of lithium-ion batteries: A novel approach for high-power and high-safety applications

In this study, we investigated the synergetic effect of a novel lithium-ion conducting hybrid oligomer [N, N′-bismaleimide-4, 4′-diphenylmethane (BMI), lithiated trithiocyanuric acid (Li-TCA) and Jeffamine®-M1000 (JA®); Li-BTJ] coating layer on a nickel-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material wrapped with highly electron-conductive single-walled carbon nanotubes (SWCNTs) to enhance electrochemical performance and thermal stability for high-power and high-safety lithium-ion batteries (LIBs). Morphological analyses using scanning electron microscopy/energy dispersive spectroscopy and transmission electron microscopy showed that the NCM811 active material surface was uniformly coated with a hybrid oligomer to form NCM811@Li-BTJ, which was subsequently wrapped with SWCNTs (NCM@Li-BTJ/SWCNT composite cathode). CR2032 coin-type cells with optimized NCM811@1 wt% Li-BTJ/0.2 wt% SWCNT composite electrodes delivered a significantly enhanced capacity retention (CR) of 90.1 % relative to that of bare NCM811 electrodes (CR: 82.1 %) at 1C for 200 cycles from 2.8 to 4.3 V (vs. Li/Li+). Electrochemical impedance spectroscopy and cyclic voltammetry revealed that this superior cycling performance resulted from a lower charge transfer resistance (Rct: 96.2 vs. 324.3 Ω) and a lower polarization voltage (∆V: 0.243 vs. 0.411 V vs. Li/Li+). The in-situ micro-calorimetric results presented the total heat generation (Qt) values of the coin cells with the delithiated NCM811@Li-BTJ and NCM@Li-BTJ/SWCNT electrodes at 5C and 35 °C were substantially lower by ~9.3 % and ~ 14.6 %, respectively, compared to the bare NCM811 counterpart, indicating that the surface modifications on the NCM811 active materials could prevent the LIBs' thermal instability. Furthermore, X-ray photoelectron spectroscopy studies revealed that the Li-BTJ hybrid oligomer coating layer effectively suppressed the formation of residual Li side products such as Li2CO3 evidently on the surface of the NCM811 active material particles, thereby inhibiting undesirable side reactions. Post-mortem analyses of the dual-modified NCM811 electrode after cycling revealed that the microstructure and particle morphology of the NCM composite cathode material were extensively maintained through the synergistic effects of the Li-BTJ ion-conductive and SWCNTs electron-conductive agents.

Investigation of Microstructures and Mechanical Properties of Al2024/6061/7075-Graphene Composites

This study aimed to compare the mechanical properties and microstructures of Al2024-graphene, Al6061-graphene, and Al7075-graphene composites produced by the powder metallurgy and induction heat treatment method. The effects of graphene content (0.15, 0.30, and 0.45wt.%), heat treatment (sintering and induction heat treatment), and matrix material (Al2024, Al6061, and Al7075) on the microstructure and mechanical properties of composites were investigated. Compared to Al2024, Al6061 and Al7075 alloys, the compressive strength of Al2024-0.15graphene, Al6061-0.15graphene and Al7075-0.15graphene composites increased by 33.74%, 24.9% and 32%, respectively. The highest hardness (164±1.5 HV), compressive strength (506±5 MPa), and apparent density (2.65 g/cm3) were achieved in sintered and induction heat-treated Al7075-0.15%graphene composite. As a result, it was determined that graphene is an effective reinforcement element. It has been determined that induction heat treatment improves the microstructure and mechanical properties of composite materials. Therefore, it has been stated that induction heat treatment significantly affects the mechanical properties of composites.

Construction of microstructurally controllable B/BaCrO4 particles based on droplet microfluidic technology for enhanced usability and delay precision

Tuning the microstructure of composite energetic materials is an effective way to improve charging, safety, and combustion performance. In this paper, boron (B)/barium chromate (BaCrO4) composite particles with controllable microstructure were prepared using droplet microfluidic technology (DMT). Based on the theory of droplet template self-assembly, composite particles with controllable morphology, size, and composition were prepared, revealing the regulation mechanism of the particle microstructure. The composite particles prepared using DMT exhibit a uniform distribution of characteristic elements, high circularity, smooth surface, enhanced bulk density, and excellent flow properties. The thermal decomposition characteristics, safety, and combustion properties of the samples were investigated by thermal weight loss, mechanical sensitivity, and combustion tests. Thermal weight loss and mechanical sensitivity tests showed that the samples had stable thermal decomposition properties and significantly increased mechanical stability compared to the control. The combustion test results showed that the DMT-prepared samples had a short ignition response time and significantly improved delay precision. This paper presents a straightforward method for preparing B/BaCrO4 particles with high delay accuracy, which can serve as a reference for preparing other composites.

Microstructure reconstruction of 2D/3D random materials via diffusion-based deep generative models

Microstructure reconstruction serves as a crucial foundation for establishing process–structure–property (PSP) relationship in material design. Confronting the limitations of variational autoencoder and generative adversarial network within generative models, this study adopted the denoising diffusion probabilistic model (DDPM) to learn the probability distribution of high-dimensional raw data and successfully reconstructed the microstructures of various composite materials, such as inclusion materials, spinodal decomposition materials, chessboard materials, fractal noise materials, and so on. The quality of generated microstructure was evaluated using quantitative measures like spatial correlation functions and Fourier descriptor. On this basis, this study also achieved the regulation of microstructure randomness and the generation of gradient materials through continuous interpolation in latent space using denoising diffusion implicit model (DDIM). Furthermore, the two-dimensional microstructure reconstruction was extended to three-dimensional framework and integrated permeability as a feature encoding embedding. This enables the conditional generation of three-dimensional microstructures for random porous materials within a defined permeability range. The permeabilities of these generated microstructures were further validated through the application of the lattice Boltzmann method. The above methods provide new ideas and references for material reverse design.

Effects of external influencing factors on the microstructure and physico-mechanical characteristics of glass-reinforced polymer composite material based on polyimide binder

The article presents the results of experimental studies of the effects of external influencing factors (natural exposure in climatic zones, such as a temperate climate and a climate with an industrial atmosphere, during accelerated climatic tests in a thermal humidity chamber, during thermal aging, exposure in technical environments) on the microstructure and physical and mechanical characteristics of a glass-reinforced polymer composite material grade VPS-72 based on polyimide binder grade VS-51. The state of the surface of fiberglass samples after exposure was studied for one year.

Investigation of the inner microstructure of composite materials during their densification by scanning electron microscopy – LSM:YSZ electrode case study

An understanding of the high-temperature processes, such as sintering, remains a challenge despite its paramount importance, and has yet to be achieved by the scientific community. Scanning electron microscopy is a valuable technique for investigating morphological changes, including elemental composition, by means of an energy-dispersive X-ray detector associated with these processes, with high resolution in-situ. Historically, this technique has been limited to experiments conducted at ambient temperature. However, by integrating scanning electron microscopy with a MEMS® heating chip, this limitation can be overcome, enabling the study of solid-state processes at temperatures of up to 1 200 °C. This study demonstrates one potential application of in-situ scanning electron microscopy – the densification of La1-xSrxMnO3-δ : (ZrO2:Y2O3) composite. This material, employed as an oxygen electrode in solid oxide cells, exhibits a complex microstructure. Achieving a balance between effective particle interconnection, ensuring high electric conductivity, and efficient mass transport through its porous structure is crucial. A comprehensive understanding of microstructure and surface composition evolution during the sintering process is vital to addressing trade off when optimizing densification conditions. It was shown that the densification of La1-xSrxMnO3-δ : (ZrO2:Y2O3) composite occurs in two steps. At 900 °C a significant additional porosity emerged due to the La1-xSrxMnO3-δ phase shrinkage (densification). The main densification process at 1 150 °C then acts as a self-healing mechanism, leading to the formation of a well-interconnected microstructure. Interparticle ligament formation is exclusively induced by the La1-xSrxMnO3-δ phase. Notably, no common degradation processes, such as La2Zr2O7 formation, were observed under the experimental conditions employed. This study underscores the promise of scanning electron microscopy with a heating chip extension for in-situ investigations pertinent to various high-temperature technologies.

Synergistic effects of steel slag and metakaolin in cementitious systems: Packing properties, strength, and microstructure

This study investigates the synergistic effect of steel slag (SS) and metakaolin (MK) on cementitious systems. The compressive strength, flowability, packing properties, hydration products, and microstructure of composite cementitious materials containing SS and MK are investigated using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope with energy-dispersive X-ray spectroscopy, mercury intrusion porosimetry, and surface fractal analysis. The results show that the incorporation of MK into the SS-cement system increases the wet packing density and generates calcium silicate hydrate with low Ca/Si and high Al/Ca ratios, thus increasing the compressive strength. In addition, the pore structure is refined. This study facilitates the sustainable and high-value utilization of SS and MK.