Packing Behavior Research Articles

A high Z′ structure of an organic salt with unusually high phase stability, nanoindentation, and mechano and vapo-fluorochromism

Structure (1) with very unique crystal packing and multi-stimuli responsive behaviour is reported. The absence of polymorphism in 1 is supported by experimental studies. Hirshfeld and nanoindentation studies are also reported.

Sequence-controlled alternating block polychalcogenophenes: synthesis, structural characterization, molecular properties, and transistors for bromine detection.

Sequence-controlled polychalcogenophenes have attracted much interest in terms of synthesis, structure and function in polymer science. For the first time, we developed a new class of alternating block conjugated copolymers denoted as poly(alt-AB)x-b-(alt-AC)y where both blocks are constituted by an alternating copolymer. 3-Hexylthiophene (S), 3-hexylselenophene (Se) and 3-hexyltellurophene (Te) are used as A, B and C units to assemble three sequence-controlled polychalcogenophenes P(SSe)b(STe), P(SSe)b(SeTe) and P(STe)b(SeTe) which are prepared by adding two different Grignard monomers in sequence to carry out Ni(dppp)Cl2-catalyzed Kumada polymerization. The molecular weight, dispersity, and length of each block (x = y) and main-chain sequence can be synthetically controlled via the catalyst transfer polycondensation mechanism. The polymer structures, i.e. alternating block main chain with high side-chain regioregularity, are unambiguously confirmed by 1H-NMR and 13C-NMR. The optical and electrochemical properties of the polymers can be systematically fine-tuned by the composition and ratio of the chalcogenophenes. From GIWAXS measurements, all the polymers exhibited predominantly edge-on orientations, indicating that the packing behaviors of the alternating block polychalcogenophenes with high regioregularity are inherited from the highly crystalline P3HT. P(SSe)b(STe) exhibited a hole OFET mobility of 1.4 × 10-2 cm2 V-1 s-1, which represents one of the highest values among the tellurophene-containing polychalcogenophenes. The tellurophene units in the polymers can undergo Br2 addition to form the oxidized TeBr2 species which results in dramatically red-shifted absorption due to the alternating arrangement to induce strong charge transfer character. The OFET devices using the tellurophene-containing polychalcogenophenes can be applied for Br2 detection, showing high sensitivity, selectivity and reversibility.

Epitaxial growth of ultrathin two-dimensional pentacene film with standing-up molecular geometry on nano-size-curved graphene surface

Molecule packing behavior at organic and graphene interface is essential for graphene-based organic electronics since charge carriers are transported within the very few organic layers nearest to graphene substrate. Although organic molecules especially the ones with planar aromatic rings usually adopt recumbent geometry on graphene substrate owning to the maximized π-π interaction, the alignment of organic molecules may be influenced by modifying the interfacial nature between organic molecules and graphene. Here, epitaxy growth of two-dimensional ultra-thin pentacene film with standing-up molecular geometry was observed for the first time on graphene with periodic nano-sized buckling structure. The curvature and strain of graphene was found collectively responsible for the standing-up geometry of pentacene and its oriented growth on graphene surface. This study provides a feasible way for controlling molecular epitaxy on 2D materials interfaces toward functional heterostructures.

A first principles study of nonlinear optical properties of a quinoline derivative

AbstractA quinoline derivative, 4‐(quinolin‐2‐ylmethylene)aminophenol was synthesized and structurally characterized by single crystal X‐ray diffraction. The crystal packing behavior and intermolecular interactions were examined by Hirshfeld surface analyses, 2D fingerprint plots and QTAIM analysis. The second order nonlinear response of 4‐(quinolin‐2‐ylmethylene)aminophenol molecule immersed in DMSO was investigated at PCM/DFT/CAM‐B3LYP/6–311++G(d,p) level. Theoretical calculations of the Hyper‐Rayleigh scattering (HRS) first hyperpolarizability were performed using two different procedures, the Sum‐over‐states scheme and the energy derivative method from Gaussian16. The HRS first hyperpolarizability results were compared with obtained for other organic compounds and shown that the 4‐(quinolin‐2‐ylmethylene)aminophenol presents a good nonlinear optical response.

Film formation of hard‐core/soft‐shell latex particles

AbstractMultiphase latex particles can be used to overcome some of the limitations with regards to the mechanical properties of films cast from homogeneous latexes while maintaining a reasonably low minimum film formation temperature (MFFT). In this work, we focus on the synthesis and film formation behavior of a series of hard‐core/soft‐shell latexes with varying compositions. It is shown that below a hard‐core content of around 60 wt% the MFFT is almost exclusively dependent on the glass transition temperature of the polymer that forms the soft‐shell. Above hard‐core contents of 60 wt% there is an abrupt increase of the MFFT and film formation is significantly restricted. This behavior is ascribed to the packing behavior of the hard phase. It is shown that the MFFT can be decreased by the use of blends of core‐shell particles of different size such that the packing fraction of the hard domains is improved. This is demonstrated by the counterintuitive result that a blend of two latexes with high MFFT can result in a latex with significantly reduced MFFT. The mechanical properties of the resulting films are also explored in order to determine the limits of hard‐core/soft‐shell systems with regards to their use in coatings applications.

The Role of Balancing Carrier Transport in Realizing an Efficient Orange-Red Thermally Activated Delayed-Fluorescence Organic Light-Emitting Diode.

Simultaneously realizing improved carrier mobility and good photoluminescence (PL) efficiency in red thermally activated delayed-fluorescence (TADF) emitters remains challenging but important. Herein, two isomeric orange-red TADF emitters, oPDM and pPDM, with the same basic donor-acceptor backbone but a pyrimidine (Pm) attachment at different positions are designed and synthesized. The two emitters show similarly good PL properties, including narrow singlet-triplet energy offsets (0.11 and 0.15 eV) and high photoluminescence quantum yields (ca. 100 and 88%) in doped films. An orange-red organic light-emitting diode (OLED) employing oPDM as an emitter achieves an almost twice as high maximum external quantum efficiency (28.2%) compared with that of a pPDM-based OLED. More balanced carrier-transporting properties are responsible for their contrasting device performances, and the position effect of the Pm substituent leads to significantly distinct molecular packing behaviors in the aggregate states and different carrier mobilities.

X-ray computed tomography for advanced geometrical measurements of metal powders and enhanced surface topography analyses of additively manufactured parts

Metal powder has a significant influence on the quality and performance of laser powder bed fusion (LPBF) processes and products. A key requirement for metal powder is to have shape and size distribution designed to have adequate flowability, packing behavior and laser absorption, as well as to fabricate parts with acceptable density, surface finish and mechanical properties. Accurate three-dimensional (3D) characterizations of powder particles are fundamental to enable relevant research, for example on powder reuse and material waste reduction in LPBF. This work studies advanced measurement approaches, based on X-ray computed tomography (CT), for the 3D geometrical characterization of powder particles. The work includes comparisons with conventional powder characterization methods, considering different materials and powder morphologies. Results show the potential of the CT-based approaches to provide accurate and complete 3D powder geometrical measurements, and to exploit the obtained results for the enhancement of surface topography analyses and LPBF development. • Accurate 3D characterizations of metal powder are fundamental to improve the LPBF process. • Comparison of characterization methods for different materials and morphologies. • X-ray computed tomography enables a complete 3D geometrical characterization of powder. • CT powder characterization is exploited to enhance surface topography analyses and LPBF development.

A Comprehensive Numerical and Experimental Study for the Passive Thermal Management in Battery Modules and Packs

Cooling plates in battery packs of electric vehicles play critical roles in passive thermal management systems to reduce risks of catastrophic thermal runaway. In this work, a series of numerical simulations and experiments are carried out to unveil the role of cooling plates (both between cells and a bottom plate parallel to the cell stack) on the thermal behavior of battery modules and packs under nail penetrations. First, we investigated the role of side cooling plates on the thermal runaway propagation mitigation in battery modules (1S3P) and packs (3S3P) by varying the key parameters of the side cooling plates, such as plate thicknesses, thermal contact resistances, and materials. Then, three important factors for passive thermal management systems are identified: (i) thermal mass of side cooling plates, (ii) interfacial thermal contact resistances, and (iii) the effective heat transfer coefficients at exterior surfaces. The roles of bottom cooling plates on thermal runaway propagation mitigation in 1S3P and 1S5P battery modules are numerically investigated by comparing the thermal behavior of the modules with only side cooling plates and with both side and bottom cooling plates.

The influence of bioturbation on reservoir quality: Insights from the Columbus Basin, offshore Trinidad

Nine facies are recognised in two mid-Pliocene cores from the Columbus Basin, offshore east coast Trinidad. Facies successions are consistent with deposition within a deltaic-shoreface continuum. Lower shoreface deposits are heavily bioturbated by Scolicia, Asterosoma, Thalassinoides, Teichichnus, Palaeophycus and other elements of the Cruziana Ichnofacies whereas middle shoreface sandstone beds contain sand-filled burrows of the Skolithos Ichnofacies. Deltaic deposits record coarsening-upward successions with evidence of freshwater influx such as synaeresis cracks, fluid muds, and dispersed organic detritus. Prodelta and distal delta front deposits comprise heterolithic beds and contain sporadically distributed and diminutive structures belonging to the Phycosiphon Ichnofacies. Hummocky cross-stratification is prominent in storm-dominated proximal delta front sandstone deposits that are sparsely bioturbated by Ophiomorpha, Skolithos and other elements of the Rosselia Ichnofacies. Cryptic bioturbation is common at the top of these beds. Thin section examination, core plug analysis, and numerical modelling of the facies were undertaken to better understand fluid flow in bioturbated strata of the Columbus Basin. Whereas lithology and texture remain the primary control on reservoir quality, examples of biogenically enhanced permeability are present in the P3 and P7 cores. The highest permeability values are associated with highly bioturbated middle shoreface deposits that comprise clean, sand-filled burrows. Favourable permeability measurements are also attributed to cryptically bioturbated delta front sandstone beds. The latter display higher permeabilities when compared to unbioturbated and sparsely sandstone beds. Biogenic activity contributed to reduced permeabilities in lower shoreface and distal delta front deposits owing to extensive sediment packing and sediment mixing behaviours. Relationships between permeability and bioturbation intensity indicate that effective permeability in bioturbated intervals of the P3 and P7 cores are best characterised by the arithmetic mean of permeabilities and that simple statistical calculations can aid in the analysis of highly bioturbated facies (BI = 5–6).

Chemically reduced graphene oxide/chitosan hybrid; a nanoscale “Fabric Starch”

This work reports on the formation of reduced graphene oxide/chitosan, RGO/CS, (0.1–10 wt%) hybrids via L-ascorbic acid reduction of GO-CS aqueous suspensions. Hybrids at different synthesis steps and the constituent modifications are characterized by microstructural, spectroscopic and physical methods. CS undergoes chemical-structural changes, both by interaction with GO and in the course of the chemical reduction, so that eventually, whilst there is no evidence of CS presence in the final product, we find convincing proof of its transformation to a starch-like phase via a critical examination of XRD and ATR-FTIR analysis. Hybrids show significant modifications of morphology, pore texture, apparent surface area, conductivity, and packing density vs. the pristine RGO. We elucidate more subtle effects, affecting stacking and packing behavior, by examining the capacitive storage behavior of hybrid electrodes. The electrochemical study highlights, at the best composition, a remarkable enhancement of specific/volumetric capacitance (up to 30% and 90% increase, respectively) and of rate behavior, compared to pure RGO. Overall, we show that the functioning of CS in hybrid formation can be explained through the reactive attachment of CS molecules onto RGO sheets, forming a starch-like phase, which stiffens graphene layers mitigating crumpling, and allowing a denser packing without re-stacking.

Optimization of Densification Behavior of a Soft Magnetic Powder by Discrete Element Method and Machine Learning

Densification of amorphous powder is crucial for preventing magnetic dilution in energy-conversion parts owing to its low coercivity, high permeability, and low core loss. As it cannot be plastically deformed, its packing fraction is controlled by optimizing the particle size and morphology. This study proposes a method for enhancing the densification of an amorphous powder after compaction, achieved by mixing three types of powders of different sizes. Powder packing behavior for various powder mixing combinations is predicted by an analytical model (i.e., Desmond’s model) and a computational simulation based on the discrete element method (DEM). The DEM simulation predicts the powder packing behavior more accurately than the Desmond model because it incorporates the cohesive and van der Waals forces. Finally, a machine learning model is created based on the data collected from the DEM simulation, which achieves a packing fraction of 94.14% and an R-squared value for the fit of 0.96.

Electrification of a Class 8 Heavy-Duty Truck Considering Battery Pack Sizing and Cargo Capacity

The design and performance optimization of fully electric trucks constitute an integral goal of the transport sector to meet climate emergency measures and local air quality requirements. Most studies in the literature have determined the optimum pack size based on economic factors, without accounting for the details of pack behavior when varying the size. In this paper, the effect of battery pack sizing and cargo capacity of a class 8, 41-ton truck on its overall energy performance and technical parameters of its powertrain is investigated. For this purpose, the proposed electric truck is designed and mathematically modelled using AVL CRUISE M software. The second-order equivalent circuit model is developed to predict the battery packs’ parameters. The proposed battery pack model is extracted from experimental analysis on SONY VTC6 lithium-ion batteries performed in the lab. The weight changes due to adding the battery packs to the truck are also estimated and have been taken into account. The mathematical model of the powertrain is simulated in the long-haul driving cycle considering different cargo capacities and battery pack sizes. The results of this study revealed that the battery pack voltage reached its minimum value when the maximum cargo capacity was applied for the 399 kWh battery pack. In addition, increasing the occupied cargo capacity from 10% to 100% resulted in an increase in the regenerative brake energy of up to 9.87 kWh, while changing the battery size imposed minimal impacts on regenerative brake energy recovery as well as energy consumption.

Drone-based ground-penetrating radar (GPR) application to snow hydrology

Abstract. Seasonal snowpack deeply influences the distribution of meltwater among watercourses and groundwater. During rain-on-snow (ROS) events, the structure and properties of the different snow and ice layers dictate the quantity and timing of water flowing out of the snowpack, increasing the risk of flooding and ice jams. With ongoing climate change, a better understanding of the processes and internal properties influencing snowpack outflows is needed to predict the hydrological consequences of winter melting episodes and increases in the frequency of ROS events. This study develops a multi-method approach to monitor the key snowpack properties in a non-mountainous environment in a repeated and non-destructive way. Snowpack evolution during the winter of 2020–2021 was evaluated using a drone-based, ground-penetrating radar (GPR) coupled with photogrammetry surveys conducted at the Ste-Marthe experimental watershed in Quebec, Canada. Drone-based surveys were performed over a 200 m2 area with a flat and a sloped section. In addition, time domain reflectometry (TDR) measurements were used to follow water flow through the snowpack and identify drivers of the changes in snowpack conditions, as observed in the drone-based surveys. The experimental watershed is equipped with state-of-the-art automatic weather stations that, together with weekly snow pit measurements over the ablation period, served as a reference for the multi-method monitoring approach. Drone surveys conducted on a weekly basis were used to generate georeferenced snow depth, density, snow water equivalent and bulk liquid water content maps. Despite some limitations, the results show that the combination of drone-based GPR, photogrammetric surveys and TDR is very promising for assessing the spatiotemporal evolution of the key hydrological characteristics of the snowpack. For instance, the tested method allowed for measuring marked differences in snow pack behaviour between the first and second weeks of the ablation period. A ROS event that occurred during the first week did not generate significant changes in snow pack density, liquid water content and water equivalent, while another one that happened in the second week of ablation generated changes in all three variables. After the second week of ablation, differences in density, liquid water content (LWC) and snow water equivalent (SWE) between the flat and the sloped sections of the study area were detected by the drone-based GPR measurements. Comparison between different events was made possible by the contact-free nature of the drone-based measurements.

Pseudopolymorphism of a luminescent anthracene‐pentiptycene π‐system: The persistent alkyl‐pentiptycene threading mode

AbstractUnderstanding the crystal packing behavior of a luminescent π‐conjugated system would facilitate the design of crystals of the desired luminescence properties. Crystal pseudopolymorphism provides a great opportunity for such a purpose and meanwhile for tuning the solid‐state luminescence properties of a molecular system via crystallization in different solvents. Herein, we report an example of structural modification that converts a polymorphic anthracene‐pentiptycene π‐system (1) into a pseudopolymorphic counterpart (2), which displays polymorph‐dependent fluorescence color and [4 + 4] photodimerization activity. The five pseudopolymorphs of 2 (crystal notation 2/Solvent, and Solvent = THF, Hex, CHCl3, DCM, and MeOH) have a common feature of forming one‐dimensional (1D) columnar alkyl‐pentiptycene threading mode. The subsequent packing of the 1D columns depends on the size of the included solvents, leading to two major types of pentiptycene‐based framework. One of the frameworks possesses 1D solvent channels that account for 14–18% of the unit cell volume, and the other type has small solvent cavities. A crystal with partial hexane inclusion (i.e., 2/Hex') is also obtained, which provides insights into the stability of the apohost structure. Intriguing solvent guest effects on the fluorescence properties of 2/Solvent are also noted.

A methodology to model and validate electro-thermal-aging dynamics of electric vehicle battery packs

It is becoming increasingly important for power system engineers to have accurate yet simple-to-realize models that simulate electric vehicle (EV) battery pack behaviour. This paper proposes a methodology to model and validate the main dynamics – electrical, thermal and aging – that characterize Li-ion batteries without disassembling them from the vehicle. The methodology consists of three steps. The first is the model implementation of the battery pack, considering the mentioned dynamics and their interdependencies. Next, the electrical and thermal parameters are experimentally derived from a Nissan LEAF 40 kWh battery pack. Third, the overall model is validated through real tests. Only electrical power and ambient temperature are provided as model inputs, and the output is compared with the collected measurements from the battery pack. Results show that the model predicts the electro-thermal battery pack behaviour with errors below 5%. The estimated capacity decrease deviates from the measurements and battery management system (BMS) readings up to one percentage point. We conclude our paper by discussing the uncertainty regarding this estimation and the limitations introduced by working with EV battery packs, both on model implementation and field validation.

Temperature-mediated construction of a plantar pressure-relieving, thermally insulating, and biodegradable thick-walled cellulose sponge insole

Plantar pressure can be reduced and wearing comfort can be improved by using cushioning materials such as insoles. However, the biodegradation of most commercial insoles is difficult, incurring high disposal costs both economically and environmentally. Herein, we present a temperature-mediated approach for constructing a plantar pressure reducing, thermally insulating, and biodegradable thick-walled cellulose sponge (TWCS) insole from cotton linters. 3D Raman imaging and crystallographic test results demonstrated that freezing temperature affected the packing behavior of the dispersed cellulose at the ice crystal boundary, resulting in a marked distinction between wall thicknesses and crystallinity of sponges, from 0.36 μm and 0.39 to 7.74 μm and 0.46, at distinguishing temperatures (−25 ˚C, −78 ˚C, and − 198 ˚C). Benefiting from the thick-walled structure generated during the temperature-mediated interfacial assembly, the mechanical strength of the TWCS was significantly increased by 5.6 times to 569 kPa, accompanied by significantly enhanced structural stability, pressure-relieving, and thermal insulating characteristics. Subsequently, we designed TWCS as a biomass insole, and its performance was thoroughly examined using plantar pressure testing, thermal performance assessment, finite element simulation, and degradability investigations. The results demonstrate that TWCS can effectively decompress (1-fold pressure reduction), disperse external stresses, prevent heat loss and complete degradation within 50 days under biological conditions, and can potentially replace traditional petroleum-based sponge insoles.

Pacing and packing behaviour in elite and world record performances at Berlin marathon

ABSTRACT The aim of this study was to compare pacing and packing behaviours between sex and performance level at elite Berlin marathon races. Official electronic split and finishing times from 279 (149 male and 130 female) marathon performances, including 5 male world records, were obtained from 11 Berlin marathon races held from 2008 to 2018, and from two previous world records and the second world all-time fastest performance also achieved at that same Berlin course. Male performances displaying an even pacing behaviour were significantly faster than those adopting a positive behaviour (p < 0.001; d = 0.75). Male world records were characterized by even profiles with fast endspurts, being especially remarkable at world all-time two fastest performances which were assisted by the use of a new shoe technology. Female marathon runners decreased their speed less than men during the second half marathon and especially from the 35th km onwards (p < 0.001; 0.51 ≤ d ≤ 0.55). The latest race stages were usually run individually in both sexes. Significant pace differences between performance groups at every race segment were found in women (p < 0.01; 1.0 ≤ d ≤ 2.0), who also covered an important part of the race alone. Prior to participation in meet marathon races such as Berlin marathon, elite runners should select the group that they will join during the race according to their current performance level as a preassigned pace set by a pacemaker will be adopted. Therefore, they could follow an even rather than positive pacing behaviour which will allow them to achieve a more optimal performance. Highlights Prior to participation in meet marathon races such as Berlin marathon, elite runners should select the group that they will join during the race according to their current performance level as a preassigned pace set by a pacemaker will be adopted. Athletes could follow an even rather than positive pacing behaviour which will allow them to achieve a more optimal performance. Female runners should consider being paced by a male runner of greater performance level as runners of both sexes are allowed to run the race altogether during this type of races.

Microstructures and strengths of microporous MgO–Al2O3 ceramics from Al(OH)3 and calcined magnesite

AbstractSeven microporous MgO–Al2O3 ceramics with an Al2O3 content of 15–90 wt% were prepared using Al(OH)3 and calcined magnesite as raw materials. A wet mixing process was employed during sample preparation to transform the calcined magnesite with a larger particle size to smaller Mg(OH)2 particles. The in situ decomposition synthesis method and the Kirkendall effect were utilized to produce and control the pore structure of the microporous MgO–Al2O3 ceramics. There were two kinds of pores in the microporous MgO–Al2O3 ceramics. The first one resulted from the in situ decomposition of Al(OH)3 and Mg(OH)2 particles, which were small and equally distributed. Another one originated from the position of the Mg(OH)2 particles due to the Kirkendall effect caused by MgO diffusion. They were similar in size to the Mg(OH)2 pseudomorph particles. Simultaneously, the Al2O3 content affected the packing behavior and the spinel formation, which changed the characteristics of the pores and necks among the particles. These mechanisms also affected the strengths of the microporous MgO–Al2O3 ceramics. Thus, when the Al2O3 content was 45–90 wt%, the microporous MgO–Al2O3 ceramics had a high compressive strength (10.0–18.3 MPa) and apparent porosity (52.2%–58.4%).

Percolation threshold and excluded volume of overlapping spherotetrahedral particle systems: Shape evolution from tetrahedron to sphere

Understanding the excluded volume of particle is of great importance in the evaluation of continuum percolation and random packing behaviors of particle systems in disordered media. Particle shape plays a crucial role in determining its excluded volume and the percolation threshold of particle systems. Real particles in nature usually have rounded corners. In this work, the rounded corner effect on the excluded volumes of spherotetrahedral particles and the percolation thresholds of continuum percolation systems of randomly orientated congruent overlapping spherotetrahedral particles, is systematically investigated. We characterize the shape evolution of spherotetrahedron from an ideal tetrahedron (Trr = 0) to a perfect sphere (Trr = 1) via a rate of roundness Trr as its shape descriptor. The excluded volume of spherotetrahedron is theoretically formulated by the second virial coefficient and the geometrical properties of spherotetrahedron. In addition, the excluded volume is also simulated in order to verify the correctness of the theoretical model. On the other hand, the percolation threshold of congruent overlapping spherotetrahedron systems is analyzed by using a Monte Carlo finite-size scaling analysis. The critical volume fraction ϕc representing the percolation threshold as the particle shape evolution from Trr = 0 to Trr = 1 is determined with a high degree of accuracy. Moreover, a linear fitting function on Trr for the percolation threshold is proposed and shown to yield accurate predictions of ϕc. We find that ϕc is a universal monotonic increasing function of Trr, as well as the dimensionless excluded volume is a universal monotonic decreasing function of Trr. This work has practical applications in predicting effective transport and mechanical properties of disordered media.

Microstructures and properties of microporous mullite‐corundum aggregates for lightweight refractories

AbstractFive microporous mullite‐corundum refractory aggregates were prepared from Al(OH)3 and kaolinite gangue through in situ decomposition synthesis technique. The effects of the sintering temperature (1400–1600°C) and the particle sizes of raw materials (20.6–94.5 μm) on the microstructures and strengths of the aggregates were investigated through X‐ray diffractometer, scanning electron microscopy, and energy‐dispersive spectrometer etc., to find out the technological conditions to be controlled in industrial production. The higher sintering temperature promoted the reaction between Al(OH)3 and kaolinite gangue, leading to the development of primary‐mullite as well as the generation of secondary‐mullite, which promoted the formation of the neck and improved the strength. Meanwhile, the dense mullite layers were formed continuously on the surface of Al(OH)3 pseudomorphs, making the micropores inside the pseudomorphs become closed pores, which increased the closed porosity of the aggregates. The reduction of the particle sizes of raw materials changed the particle packing behavior, accelerated the rearrangement of the Al(OH)3 pseudomorph particles during the process of reactive sintering, and then reduced the closed porosity. To realize the industrial production of microporous mullite‐corundum refractory aggregate with high strength (103 MPa) and high closed porosity (16.1%), the sintering temperature should be at about 1600°C, and the median diameter of raw materials should be at 94.5 μm.