Insulation Performance Research Articles

Performance investigation of solution-processed semi-transparent perovskite solar cells in building sectors

Semi-transparent perovskite solar cell (PSC) windows have received much attention from scholars due to their remarkable power generation capacity and thermal insulation performance. However, considering the complexity of their fabrication process, and the significant decrease in power generation efficiency when scaling up to large-sized solar modules. To solve the above problems, this study developed a scalable production technological process to prepare translucent PSC modules, in which large-area chalcogenide thin films were prepared by a scratch-coating method. The prepared PSC module has an average visible light transmittance of 20.1 % and shows a maximum power conversion efficiency of 3.92 %. Experimental tests were conducted to investigate its photo-thermal regulation performance concerning the existing common window. The results show that the newly developed photovoltaic window reduces the indoor air temperature by 1.4 °C while the illuminance is reduced by about 59.2 % compared to the common window. A further simulation is performed by Energyplus, with a conclusion that PSC windows can decrease glare probability by 24.7 %–45.7 %, diminish building energy usage by 26.6 %–59.6 %, and achieve up to 469.9 kWh power generation in Harbin, China. The investigation of this paper paves the technical and foundational way for the large-scale application of PSC in building sectors.

Solar PV vacuum glazing (SVG) insulated building facades: Thermal and electrical performances

As fire emergencies and energy saving demand of buildings have grown around the globe, concerns have been raised about the flammability of conventional external insulation materials in cold weather areas. In this paper, solar PV vacuum glazing (SVG) was proposed as a promising alternative to traditional external insulation layers of buildings due to its incombustible nature and superior thermal insulation performance. To assess the thermal and electrical performances of SVG-insulated facades, a heat transfer model and an effective absorptance calculation model for SVG-insulated façades were developed and validated against experimental data. Results showed that SVG-insulated facades exhibited significantly lower U values, ranging from 44.1% to 47.5% less than those of traditional concrete walls (without insulation layer). Additionally, the application of Low-emissivity (Low-e) coatings on the glazing could further reduce the U value from 2.05 W/(m2·K) to 0.647 W/(m2·K), making SVG-insulated facades competitive with traditional insulation walls. The secondary heat transfer factor (SHTF), defined as the ratio of indoor heat gain from solar radiation absorbed by building facades to incident solar radiation, was also reported for SVG-insulated facades with different solar cells (C-si, A-si, and CdTe), along with their respective efficiencies. Parametric analyses of eight parameters subsequently highlighted that their influence on the thermal performance of SVG-insulated façades was much greater than on the solar cell efficiency. Furthermore, considering the combined effect of optimal value of key influencing parameters, the lowest U value of 0.153 W/(m2·K) could be achieved, which represents approximately 24.6% of the U value of traditional insulation walls. This study provides compelling evidence for the adoption of SVG-insulated facades as replacements for traditional insulation walls and offers insights into optimizing their thermal performance.

Bottom-up synthesis of novel cesium ferrate (Cs2FeO4) nanorods: Tailoring the structural and optical characteristics with room-temperature ferromagnetic and colossal dielectric performance

This paper presents a detailed protocol for the synthesis and characterization of cesium ferrate nanorods, a unique material that possesses a wide range of functionalities. These include the ability to demonstrate ferromagnetism at normal ambient temperature and the capacity to modify its structural, optical, and electrical properties. The XRD patterns specify the presence of an orthorhombic alkali ferrate phase (Cs2FeO4), with the size of the crystals increasing as the temperature rises. Furthermore, the XPS spectra of Cs 3d, Fe 2p, and O 1 s exhibit the formation of substances due to the peak positions fluctuate in reaction to temperature variations. The nanorod-like structure and size distribution of materials can be visualized using TEM and SEM. The UV spectra of the samples indicate broad absorption bands ranging from the visible to the near infrared (IR) region. Calcination of the as-prepared Cs2FeO4 at 400 and 600 ºC lowered the optical band gap from 2.15 to 2.04 and 2.06 eV, respectively. The temperature's synergistic effect is crucial in transforming materials from a paramagnetic to a ferromagnetic phase. The colossal sample's dielectric constant, which varies from around 107 at 600 ºC to 106 and 105 in the lower frequency band, and electrical conductivity show substantial fluctuations depending on the frequency. Nanorod systems have interesting optical, dielectric, and ferromagnetic properties at room temperature that could be used in many areas, such as photocatalysis, energy storage, and spintronics.

Polycyclic aromatic compounds surface modulation of TiO2@SiO2 nanoparticles enhances the insulation performance of polypropylene film

Polypropylene (PP) film is an important component of metallized film capacitors. However, the insulation issues of polypropylene film significantly affect the safe and stable operation of capacitors. In this study, polycyclic aromatic compounds (PAC) were introduced to the surface of TiO2@SiO2 nanoparticles via chemical grafting, preparing Ti@Si-PAC nanofillers, to achieve modulation of the nanoparticle/PP interface. The experimental and simulation results indicate that Ti@Si-PAC/PP exhibits excellent insulation performance. The study indicates that the surface modulation of nanoparticles by PAC introduces a ‘soft interface’ between the nanoparticles and the polypropylene matrix. The ‘soft interface’ enhances the interfacial interaction, reduces dielectric loss, and introduces deep traps, exhibiting a significant inhibitory effect on carrier migration. Additionally, the introduction of PAC enhances the electron trapping capability in the interface region, which plays a positive role in quenching free radical chain reactions and reducing the damage of high-energy electrons to polypropylene molecular segments. This study provides an effective method for enhancing the insulation performance of polypropylene.

Dual-phase zirconate/tantalate high-entropy ceramics boost thermal properties and fracture toughness for thermal barrier coating materials

Working temperatures, thermal insulation performance, and life span of thermal barrier coatings (TBCs) are primarily influenced by their high-temperature stability, thermal expansion coefficients (TECs), thermal conductivity, and fracture toughness. To address the limitations of current zirconate- and tantalate-based oxides, dual-phase zirconate/tantalate high-entropy ceramics (HECs) are designed and synthesized to improve their thermal and mechanical properties. The combined effects of high entropy, high concentrations of oxygen vacancies, and relatively low phonon velocity result in glass-like thermal conductivity, with a minimum value of 1.55 W m−1 K−1 at 1200 °C. The high TECs (10.6–10.9 × 10−6 K−1 at 1400 °C) and exceptional high-temperature stability demonstrate that these materials can withstand 1300 °C for more than 300 h, significantly surpassing the performance of traditional yttria-stabilized zirconia (YSZ). Compared with YSZ (3.6 MPa m1/2) and YTaO4 (2.5 MPa m1/2), the increments in fracture toughness (4.4 MPa m1/2) of dual-phase zirconate/tantalate HECs are as high as 22.2% and 76.0%, respectively. It is evident that the designed dual-phase zirconate/tantalate HECs can effectively promote thermal properties and fracture toughness, positioning them as the next-generation TBCs with high operating temperatures and outstanding thermal insulation performance.

Enhancing flame retardancy and heat insulation performances of polyamide 66 composite film by adding CNC/Al2O3 nanohybrids

Polyamide 66 (PA66) has garnered significant attention due to its exceptional properties; unfortunately, its flammability is challenging. Adding flame retardants (FRs) is a primary approach to enhance PA66 flame retardancy. This study developed a highly flame-retardant PA66 composite film by adding corn-like functional nanohybrids (CNC/Al2O3). Interestingly, CNC/Al2O3 nanohybrids not only formed hydrogen bond interactions with PA66 but also improved crystallization properties as heterogeneous nucleating agents, resulting in the excellent mechanical properties of PA66 composite film. Remarkably, the incorporation of 3 wt% CNC/Al2O3 nanohybrids into PA66 matrix contributed to increasing the LOI to 28.5 %. The pHRR, THR, and TSR were reduced obviously by 55.7 %, 15.3 %, and 65.2 %, respectively. The excellent flame retardancy of PA66 composite film was attributed to the forming of a compact carbon layer catalyzed by the CNC/Al2O3 nanohybrids. Besides, the homogeneous distribution of CNC/Al2O3 nanohybrids endowed the composite film with excellent heat insulation, and the heat insulation rate was up to 31.9 %. Thus, such PA66 composite films with excellent flame retardancy, heat insulation, and mechanical properties could meet the broader application requirements.

Bilayer nested porous microcapsules inspired by honeycomb structures achieving efficient self-healing and intrinsic property enhancement of insulating materials

Self-healing microcapsules represent a highly promising strategy for enhancing the long-term durability of materials under prolonged service conditions. Nevertheless, the industrial application of microcapsules encounters significant challenges. This is primarily due to the dilemmas involved in guaranteeing effective repair without significantly undermining the intrinsic properties of the substrate materials. Inspired by the structure of honeycombs, this paper introduces a bilayer, nested, porous self-healing microcapsule featuring an ultra-thin, rigid shell that effectively addresses the above challenges. An ultra-thin rigid shell is first constructed to enhance mechanical strength while significantly increasing the load capacity of the healing agent. Subsequently, the subcritical water treatment method is employed to etch nanoscale through-holes on the shell surface for encapsulating the healing agent. Finally, via a cross-linking reaction, a film is formed on the surface of the porous shell to seal the holes. The test results show that the loading efficiency of the microcapsules achieves 94.4 %. Moreover, while the repair efficiency is substantially enhanced, the intrinsic properties of the matrix material are maintained, and there is additionally a measurable improvement in tensile strength and insulation performance. To our knowledge, the microcapsules that significantly enhance repair efficiency while concurrently improving the properties of the matrix have not yet been reported in previous studies.

Ultrahigh Electrostrictive Effect in Lead-Free Sodium Bismuth Titanate-Based Relaxor Ferroelectric Thick Film.

In recent years, the development of environmentally friendly, lead-free ferroelectric films with prominent electrostrictive effects have been a key area of focus due to their potential applications in micro-actuators, sensors, and transducers for advanced microelectromechanical systems (MEMS). This work investigated the enhanced electrostrictive effect in lead-free sodium bismuth titanate-based relaxor ferroelectric films. The films, composed of (Bi0.5Na0.5)0.8-xBaxSr0.2TiO3 (BNBST, x = 0.02, 0.06, and 0.11), with thickness around 1 μm, were prepared using a sol-gel method on Pt/TiO2/SiO2/Si substrates. By varying the Ba2+ content, the crystal structure, morphology, and electrical properties, including dielectric, ferroelectric, strain, and electromechanical performance, were investigated. The films exhibited a single pseudocubic structure without preferred orientation. A remarkable strain response (S > 0.24%) was obtained in the films (x = 0.02, 0.06) with the coexistence of nonergodic and ergodic relaxor phases. Further, in the x = 0.11 thick films with an ergodic relaxor state, an ultrahigh electrostrictive coefficient Q of 0.32 m4/C2 was achieved. These findings highlight the potential of BNBST films as high-performance, environmentally friendly electrostrictive films for advanced microelectromechanical systems (MEMS) and electronic devices.

Double envelope vacuum insulation panel to contribute to the long-term thermal insulation performance

Vacuum insulation panels (VIPs) have a potential to be used for retrofitting thermal insulation to existing buildings from the viewpoint of low thermal conductivity, small thickness, and light weight. However, in order to realize vacuum insulation panels applicable to building thermal insulation, it is necessary to overcome the challenge of maintaining the low pressure at which high thermal insulation performance can be achieved for several decades. The authors propose double envelope VIPs to maintain this long-term high thermal insulation performance. The double envelope VIP is fabricated by creating a single envelope VIP, wrapping the VIP with core materials, and then inserting it into the envelope for vacuum sealing. By applying the double envelope VIPs, the pressure difference and the permeation of gas in the inner VIP can be drastically reduced, resulting in a longer VIP lifetime. In this paper, the gas permeabilities of the gas barrier envelopes are experimentally estimated. Then, the pressure ageing in the double envelope VIP is calculated. The inner pressure of double envelope VIP after 50 years is 5.4 Pa for the envelope of aluminium composite film, indicating that low pressure can be maintained long-term. Next, the authors carry out accelerated test, in which the double envelope VIPs are placed in a chamber at 80oC and removed every two weeks to measure the effective thermal conductivity. Even after 141 weeks, one sample with a getter agent on the inside and a desiccant agent on the outside indicates only 10.5 % decrease in the thermal resistance. From this result, the long-term high thermal insulation performance can be obtained by fabricating double envelope VIPs.

Microstructure and corrosion resistance of novel rare-earth-zirconia doped Y2O3 plasma-sprayed coating

Y2O3 coatings are widely applied in semiconductor etching machines to protect the inner walls of aluminum alloys. This study reports the preparation of yttria-based coatings on aluminum alloy substrates using atmospheric laminar plasma spraying (ALPS) methods. In this study, four yttria-based coatings were designed and tested for their thermal performance, plasma etching resistance, and resistance to laser ablation. The rare-earth-zirconia (RE-ZrO2) doped Y2O3 coating exhibited the best thermal insulation performance, with a thermal conductivity of approximately 0.6 W m−1 k−1 at 600 °C. Plasma etching experiments demonstrated that more rare-earth fluorides were generated on the surface of the RE-ZrO2 doped Y2O3 coating, which weakened the plasma energy. Finally, the lowest etching rate was achieved. Laser ablation experiments demonstrated that the depth of the ablation pit on the surface of the RE-ZrO2 doped Y2O3 coating was shallow, indicating good laser ablation resistance. These results indicate that rare-earth-doped yttria-based coatings provide excellent corrosion protection against plasma etching and laser ablation.

Facile preparation of graphene aerogel as a thermal insulation material

A simple low temperature and cost-effective hydrothermal method via reduction self-assembly and freeze-drying was fabricated to prepare graphene aerogel (rGO). After the reduction process, most of the oxygen-containing groups in graphene oxide have been removed by ascorbic acid. The surface C/O atomic ratio detected in rGO is about 7.26. The aerogel presents a nanoporous structure. This porous structure could act as a barrier to heat conduction. By heating the graphene aerogel and using infrared thermal imager to detect the temperature, the temperature difference between the top and the bottom of the aerogel reached 80 °C, which showed excellent thermal insulation performance. In addition, by testing the thermal imaging image of graphene aerogel placed on the skin surface, it exhibited an infrared stealth effect. This carbon aerogel may offer potential for the fabrication and application for thermal insulation and infrared stealth material systems.

A comparative study on the electrical properties of Ba0.6Sr0.4TiO3 film capacitors with different top electrodes

Au/Ba0.6Sr0.4TiO3 (BST)/La0.5Sr0.5CoO3 (LSCO) and Pt/BST/LSCO ferroelectric capacitors were successfully constructed on (001) LaAlO3 substrates via off-axis magnetron sputtering. X-ray diffraction (XRD) and Phi scan patterns confirmed that the BST film was epitaxial with an out-of-plane tetragonal phase. The ferroelectric and dielectric measurements reveal that, compared with the Pt/BST/LSCO capacitor, the Au/BST/LSCO capacitor exhibits a larger coercive field (∼139.7 kV/cm), smaller permanent polarization (∼2.94 μC/cm2), and lower tunability (∼65.22 %), which may be attributed to the higher difference in work function and weaker depolarization field screen effect of the top electrode, as well as smaller interfacial capacitance of the Au/BST interface than those of the Pt/BST interface. Therefore, based on series capacitor model and leakage behavior analysis, the thickness and dielectric constant of interfacial layer are quantitatively determined to be 3.52 nm and 12.13 for Pt/BST, and 4.42 nm and 5.82 for Au/BST, respectively. Our results pave a way for improving the dielectric performance in electrically tunable microwave devices.

Insulating Material with Scale Components for High-Temperature and High-Pressure Water Applications.

Accurately measuring water holdup in horizontal wells is crucial for effectively using heavy oil reservoirs. The capacitance method is among the most widely used and accurate techniques. However, the absence of suitable insulating materials at high temperatures and pressures limits the effectiveness of capacitive water holdup measurement in heavy oil thermal recovery. This study introduces a new composite material based on an aviation-grade, special glass glaze as the insulating medium doped with inorganic components (CaSO4, MgSO4, Ca(OH)2, and SiO2). This new composite material demonstrates outstanding insulating performance under high-temperature and high-pressure conditions in water. A water environment with a high temperature of 350 °C and a pressure of 12 MPa considerably enhances the composite material's insulation. After 72 h of continuous use, the insulation performance remains 0.3 MΩ. The layers exhibit improved insulation and stability, maintaining integrity through five consecutive temperature shocks in 500 °C air and 20 °C water. XRD, IR, SEM, and TEM analyses reveal that the new composite material is amorphous after firing and that the addition of inorganic components improves the bonding between the glass glaze components and contributes to a denser structure. Simultaneously, SEM and TEM analyses indicate that adding inorganic components results in a smoother, crack-free, and more compact surface of the special glass glaze. This enhancement is crucial for the material's long-term stability in high-temperature and high-pressure water environments.

Analysis of hysteresis loops and dielectric performance in the ovalene-like system: Monte Carlo study

This Monte Carlo study offers a comprehensive analysis of the ovalene-like system, emphasizing its dielectric behavior, thermal performance and hysteresis loops. The investigation reveals intricate dynamics influenced by diverse parameters, contributing to a nuanced understanding of the system’s response. Additionally, the study scrutinizes the impact of various physical parameters on the thermal behavior of polarizations and susceptibilities. The examination thoroughly explores the influence of these parameters on loop characteristics, coercive field, and saturation behavior, unveiling the formation of multiple loops and polarization plateaus on the electric hysteresis. In summary, this study advances our understanding of the ovalene-like system’s dielectric response, thermal characteristics and hysteresis dynamics, providing valuable insights for future research and applications, particularly in advanced electronic devices.

Reuse and remanufacturing of insulated glass units

AbstractMany office and residential buildings in Europe need to be renovated in the near future to meet current energy efficiency requirements. This often comes down to updating the insulation performance of the building envelope including the windows. Most “old” windows consist of a frame and a double insulated glass unit (IGU) or even monolithic glass panes – typically without any low-e coating. These non-coated double glazings have a Ug-value of 2.7 W/m2K (single glazing even 5.2 W/m2K). Modern coated triple glazed IGUs provide Ug-values of up to 0.5 W/m2K.This paper deals with the question of how old insulating glass units can be re manufactured to match the state of the art in terms of the energy efficiency. For this purpose, dismounted IGUs from the 1980s are used. After analyzing the remaining functionality, the double IGUs are disassembled. The single glass pane is cleaned, and the old edge sealing is removed. The old glass pane is combined with a new coated low-e glass and a spacer system to form a new upgraded IGU with warm edge technology. This study demonstrates that remanufactured IGUs can achieve the performance of IGUs made from new glass.

Unification of thermal conductivity, electrical insulation, and electromagnetic shielding: A bulk thermal conductive polymer from solid waste

In the context of the ongoing advancements in high-performance chips, heat dissipation, and electromagnetic shielding within electrical and electronic equipment are becoming increasingly intricate. Plastics have garnered widespread usage in electrical and electronic equipment as prevalent framework materials. However, the challenge persists in achieving a unification of electromagnetic interference (EMI) shielding, thermal conductivity (TC), and electrical insulation performance for plastics. Herein, we capitalize on the styrene–butadiene–styrene (SBS) copolymer to integrate the merits of polymers and magnetic minerals. Utilizing pyrrhotite (Pyr) tailings and waste polystyrene (PS) as raw materials, a formable block material denoted as PS-S@SBS/Pyr has been formulated. This material exhibits commendable performance in terms of TC, electrical insulation, and EMI shielding performance concurrently. The bidirectional bridging effect of SBS effectively reduces the interfacial thermal resistance between PS and Pyr. The TC of PS-S@SBS/Pyr can reach a maximum of 1.36 W/m‧K with a resistivity greater than 108 Ω‧m. Moreover, PS-S@SBS/Pyr consistently demonstrates a stable EMI shielding effectiveness of 33.1 dB within the 8–12 GHz frequency range, with absorption shielding predominating as the underlying mechanism. This green preparation method makes efficient utilization of two main solid wastes while increasing the added value of the material.

Study on preparation and thermal insulation properties of curing foam

The thermal insulation performance of curing foam is a critical factor affecting fire extinguishing efficiency. In this study, sodium dodecyl sulfate was used as the foaming agent, and then combined with foam stabilizers, foam thickeners and inorganic powders to prepare the curing foam extinguishing agents. The result demonstrated that the addition of PEG and Xanthan gum could prolonge the 50 % drainage time of foam solution to 1.98 times compared with the foam solution without foam additives. The composite powders imparts an excellent thermal insulation and high-temperature stability to curing foam, especially the mass fractionratio of loess to cement equals to 4:6 and the water cement ratio is 0.7. Moreover, the thermal insulation tests showed that when the test temperature equalled 500 °C, the curing foam could reduce the temperature of the covered surface by 234.2 °C. Compared with the water-based foam, the thermal insulation performance was improved by 58.1 %. Finally, fire extinguishing test showed that the fire extinguishing time of curing foam is 0.47 s and 33.99 s shorter than that of water-based foam and water, respectively. The consumption of water-based foam and water fire extinguishing consumption is 1.46 times and 4.37 times that of curing foam, respectively. The excellent structural stability is due to the addition of Xanthan gum and PEG additives, which provide a more uniform distribution of bubbles and denser pores. At the same time, the mixture of loess and cement acts as a skeleton in curing foam thereby improving the stability of the integral structure and further preventing the heat transfer.

A Study on the Motion Behavior of Metallic Contaminant Particles in Transformer Insulation Oil under Multiphysical Fields.

When using transformer insulation oil as a liquid dielectric, the oil is easily polluted by the solid particles generated in the operation of the transformer, and these metallic impurity particles have a significant impact on the insulation performance inside the power transformer. The force of the metal particles suspended in the flow insulation oil is multidimensional, which will lead to a change in the movement characteristics of the metal particles. Based on this, this study explored the motion rules of suspended metallic impurity particles in mobile insulating oil in different electric field environments and the influencing factors. A multiphysical field model of the solid-liquid two-phase flow of single-particle metallic impurity particles in mobile insulating oil was constructed using the dynamic analysis method, and the particles' motion characteristics in the oil in different electric field environments were simulated. The motion characteristics of metallic impurity particles under conditions of different particle sizes, oil flow velocities, and insulation oil qualities and influencing factors were analyzed to provide theoretical support for the detection of impurity particles in transformer insulation oil and enable accurate estimations of the location of equipment faults. Our results show that there are obvious differences in the trajectory of metallic impurity particles under different electric field distributions. The particles will move towards the region of high field intensity under an electric field, and the metallic impurity particles will not collide with the electrode under an AC field. When the electric field intensity and particle size increase, the trajectory of the metallic impurity particles between electrodes becomes denser, and the number of collisions between particles and electrodes and the motion speed both increase. Under the condition of a higher oil flow velocity, the number of collisions between metal particles and electrodes is reduced, which reduces the possibility of particle agglomeration. When the temperature of the insulation oil changes and the quality deteriorates, its dynamic viscosity changes. With a decrease in the dynamic viscosity of the insulation oil, the movement of the metallic impurity particles between the electrodes becomes denser, the collision times between the particles and electrodes increase, and the maximum motion speed of the particles increases.

Rutile (In0.5Ta0.5)0.1Ti0.87O1.88F0.12 ceramics with excellent dielectric performance and thermal stability sintered at 1220 °C

TiO2-based colossal dielectric ceramics have emerged as a prominent research focus in recent years. However, their further applications have been constrained by several key limitations, including the requirement of high sintering temperature (>1400 °C), relatively high dielectric loss (>0.05, 1 kHz), and temperature stability (<200 °C). This study reports rutile (In0.5Ta0.5)0.1Ti0.87O1.88F0.12 ceramics at 1220 °C sintering using 12 % InF3 as the acceptor In3+ source, which exhibits a colossal dielectric constant (1.1 × 105) and an ultra-low dielectric loss (0.0071) at 1 kHz and room temperature, even loss values below 0.04 (20 Hz - 100 kHz). Notably, the thermal stabilities (10 kHz, 100 kHz) simultaneously satisfy X9E (Δεr/ε25 °C ≤ ±4.7 %) above 300 °C. F− not only supplies electrons to enhance the semiconductivity of grains, but also decreases the oxygen vacancy and average grain size (270 ± 12.53 nm) to improve grain boundaries resistances, which reduces dielectric loss and enhances frequency and temperature stabilities. As a result, the dielectric mechanism is mainly related to internal barrier layer capacitor (IBLC) and high grain boundary resistance. Therefore, this strategy provides a creative design for developing TiO2-based ceramics.

Fabrication of low conductivity and high strength MgO-MgAl2O4 aggregates with sub-micron pore structure

Lightweight MgO-MgAl2O4 refractory aggregates were fabricated by using fine MgO and spherical Al(OH)3 powders as starting materials. The evolutions of microstructure and pores and their effects on the properties of the specimens were investigated. During heating process, MgO crystallites diffused into the formed Al2O3 pseudomorph, producing sub-micron intra-particle pores in both MgAl2O4 cores and MgO matrix. Besides, larger inter-particle pores between the MgAl2O4 cores and MgO matrix were occurred, attributing to the Kirkendall effect resulting from in-situ spinalization. As MgO content increased from 50 wt% to 80 wt%, due to reduction of the number of the porous MgAl2O4 cores, the inter-particle pores caused by Kirkendall effect decreased sharply in both number and size, while no obvious changes occurred in the intra-particle pores as the porous MgO matrix amount increased simultaneously. The decrease of large inter-particle pores caused obvious improvement in strength but slight increase in thermal conductivity. With a further increase of MgO to 90 wt%, as the number of the porous MgAl2O4 cores reduced further and the MgO matrix densification improved obviously, intra-particle pores and thermal insulation performance reduced significantly. The specimen with 80 wt% MgO showed the best performance, with a median pore diameter of 0.26 μm, apparent porosity of 36.0 %, flexural strength of 23.9 MPa, and thermal conductivity of 2.1 W/(m·K) at 500 °C.