Good Thermal Insulation Performance Research Articles

Nickel-Fe3O4@Graphene coated lightweight carbonized wood for efficient electromagnetic interference shielding

The miniaturization and integration of electronic equipment promote electromagnetic effect radiation pollution more and more serious. The lightweight, renewable electromagnetic interference (EMI) shielding materials is urgently needed. This study developed a high temperature carbonization, Fe3O4@Graphene impregnation, and electroless Ni technique to construct a carbonized wood composite with strong EMI shielding performance using sustainable natural wood as the raw material. The Fe3O4@Graphene is distributed throughout the carbonized wood to provide the conductivity and magnetism of the reinforced composite material, and provide more interfaces to increase the dielectric loss and magnetic loss, thereby exhibiting excellent EMI shielding performance. The results show that at low thickness (2 mm) and ultra-low density (0.284 g/cm3), the CWN-7 composite exhibits excellent EMI shielding effectiveness of up to 84.2 dB in the whole X-band (8.2–12.4 GHz). At the same time, it has extraordinary compressive strength and good thermal insulation performance. This study offers a different method for creating composite multifunctional electromagnetic shields out of carbonized green wood.

Synthesis of lignin-based resin and fabrication of sustainable transparent wood based on bio-recycling concept

Transparent wood (TW) has attracted much attention in the field of energy saving building structural materials because of its high light transmittance, good thermal insulation performance and good toughness. However, the polymeric resins used in the present study to impregnate lignin-based wood templates are usually derived from petroleum-based chemical resources, which pose a fatal threat to human beings both in terms of consuming large amounts of resources and causing environmental pollution problems. It is therefore important to develop alternatives to petroleum-derived chemicals in renewable natural resources. Here, we report a green and sustainable TW production process based on the bio-recycling concept. Lignin-based sustainable resin (LSR) was prepared from waste lignin produced during delignification by polymerization of guaiacol. At the same time, according to FT-IR and NMR data analysis combined with previous studies, the synthesis mechanism of LSR was proposed, and this result provided a reference for bio-based resins made from biomass materials. The prepared lignin-based sustainable transparent wood (LSTW) has good light transmittance and good dimensional stability. In addition, the LSTW also shows good thermal insulation and indoor temperature regulation capabilities compared with the common glass.

Surface decoration of flexible Si3N4 nanowire membrane by hydroxyapatite micron-flake with excellent thermal insulation at 1300 °C

Flexible and excellent thermal insulation membranes are required as the thermal protection system materials of aerospace vehicles for next-generation space missions. Using ceramic membranes with ultralow thermal conductivity has been proved to be an effective way to protect the electronic components inside the fuselage. Herein, we decorate hydroxyapatite (HA) micron-flake onto Si3N4 nanowire membrane (SR), and investigate the thermal stability, fire-resistance and thermal insulating properties of the obtained SR decorated by HA micron-flake (SRHM). Surface decoration of HA micron-flake onto the SR results in the formation of well-interconnected junctions and the increase of interfacial thermal resistance. Due to the increased interfacial thermal resistance, the as-prepared SRHM exhibits good thermal insulation and outstanding fire-retardant performance. SRHM shows robust mechanical property with tensile strength value of 4.10 MPa, increased by 247.5% compared to the SR without the surface decoration by HA micron-flake. The thermal conductivity of SRHM is as low as 0.037 W m−1 K−1, reduced by 33.9% compared to the SR without the surface decoration by HA micron-flake. After SRHM is heated by a butane blow torch at 1300 °C for 30 min, no obvious change is observed in the macroscopic morphology. And the temperature of the backside for SRHM maintains at a stable temperature of ∼260 °C for 300 s, which is 1040 °C lower than that of the front side. Additionally, SRHM can protect the electronic components form being burnt under the heating of an alcohol lamp for 30 min. The successful preparation of such thermal insulating and fire-retardant SRHM will open up a new world for the widespread applications of ceramic membranes in the fields of aerospace vehicles.

Ice-template freeze-casting synthesis of polysilsesquioxane aerogel long fibers for broadband sound absorption

Aerogel fibers inherit the merits of aerogel and fibrous materials, such as ultralow density, large specific surface area and high flexibility, demonstrating great potential as the next generation functional fibers. Herein, an ice-template freeze-casting strategy is developed to prepare polysilsesquioxane aerogel long fibers (PALFs) similar to natural fibers in structure. During the freeze-casting, the strong mutual interaction between solid and liquid phases in the hydrogel induces uniform nucleation and continuous growth of ice crystals in confined spaces. The three-dimensional monolithic hydrogel is gradually deconstructed into one-dimensional fibrous geometries by the growing columnar ice crystals. The obtained PALFs exhibit the polygonal cross-section with a uniform mesoporous structure. After simple physical assembly, the monolithic PALFs exhibit good thermal insulation performance (as low as 25.0 mW/(m·K) at 25 °C) and high-efficiency absorption of broadband sound waves (with a noise reduction coefficient up to 0.58).

Preparation and thermal insulation performance of Al2O3[sbnd]Y2O3[sbnd]SiO2 ternary composite aerogels with high specific surface area and low density

Against the background of global energy shortages and the need for long-term flight safety of aerospace vehicles, traditional silica aerogels have the problems of insufficient temperature resistance and poor thermal insulation at high-temperatures, and are no longer able to meet the demand. In this study, a series of monolithic Al2O3Y2O3SiO2 ternary aerogels were successfully synthesized via synchronous sol–gel and ethanol supercritical drying. Both the prepared aerogels and the calcined samples at 1000 °C exhibited a complete three-dimensional network structure and a high specific surface area (up to 675.7 m2/g and 214.4 m2/g), which was attributed to the supporting effect of the Al2O3 component on the overall skeleton and the inhibiting effect of the Y2O3 component on the crystal transformation. Mullite fiber reinforced Al2O3Y2O3SiO2 aerogel composites were synthesized by vacuum impregnation using mullite fiber felt as a matrix. The prepared sample exhibit very low thermal conductivity (as low as 0.079 W⋅m−1·K−1 at 1000 °C). In summary, the good structural stability and high temperature thermal insulation performance make Al2O3Y2O3SiO2 ternary aerogel have the potential of efficient service in more application scenarios. This study provides a product optimization reference idea for the thermal insulation material industry.

A comparative study of polyurethane foam by substituting LBA using green polyurethane foam CFA‐1

AbstractPolyurethane foams are well‐known optimal thermal‐insulating materials, which have good thermal insulation performance, high strength, and lightweight properties. Here, we describe a chlorine‐free and fluorine‐free polyurethane chemical foaming agent (CFA‐1) that can react with isocyanate to release CO2 gas and foam polyurethane. We systematically studied its application performance in the field of polyurethane spraying by substituting the current most advanced and environment‐friendly physical foaming agent 1‐chloro‐3,3,3‐trifluoroprop‐1‐ene in different proportions. The results show that highly competitive mechanical properties lead to economical, environment‐friendly, and efficient features. The lower thermal conductivity, more compact and smaller bubble structure, and excellent compression strength were achieved by tuning the proportion of CFA‐1 from 20% to 60%. Thus, a promising material system was established for the development of the rigid polyurethane foam industry.

Effective thermal conductivity of lightweight porous concrete:theoretical models and application

Lightweight porous concrete blocks have become one of the preferred energy-saving envelope materials for modern buildings due to their good thermal insulation performance. This paper reviews the extensive literature on different theoretical models for the effective thermal conductivity of porous concrete blocks. The advantages and limitations of different models, including the pore structure, fractal theory, and thermal conductivity models, are summarized. The applicability and challenges of each lightweight porous concrete model are discussed in detail. It can be concluded that more research on lightweight porous concrete blocks is necessary to improve the theoretical thermal conductivity model by incorporating parameters related to indoor thermal and humid environments.

Temperature and strain characteristics of ceramic-reinforced polyurethane insulation decorative board under artificial accelerated aging conditions

As a new type of thermal insulation material, ceramic-reinforced polyurethane insulation decorative board (IDB) has been applied to a certain extent, but changes in the temperature and strain between this material and the substrate wall during the aging process remain unclear. In this study, an external insulation composite system with ceramic-reinforced polyurethane IDB was subjected to 60 heat-rain cycles, and the temperature and strain at the interface between the IDB and the substrate wall were measured. The results show that the temperature of the substrate wall is about 35 °C lower than the highest temperature of the environmental box, and the temperature fluctuation of the substrate wall during 60 heat-rain cycles always maintains at about 5 °C, which indicates that the ceramic reinforced polyurethane IDB has good thermal insulation performance and durability. During the heat-rain cycles, the vertical strain varies from −750 με to + 2750 με, while the horizontal strain varies from −250 με to + 500 με, indicating that the horizontal and vertical strains have serious inhomogeneity. This local inhomogeneity may be an important reason for the aging and cracking of the IDB. The characteristics of temperature and strain could provide a reference for analyzing the synergistic effect and disbonding mechanism of the interface between the IDB and the substrate wall, and give some guidance for the design and construction of external insulation composite systems.

Sound absorption and thermal insulation performance of sustainable fruit stone panels

The sound absorption and thermal insulation behavior of panels made of different fruit stones, including peach, apricot, plum, date, and black cherry, were investigated. To this end, samples in the crushed and uncrushed forms were fabricated with thicknesses of 30 and 50 mm. The FE-SEM (Field Emission Scanning Electron Microscopy) and Atomic Force Microscopy (AFM) images showed that the studied stones have different morphological and topological surfaces, which in turn lead to different sound absorption coefficients (SACs) and effective thermal conductivities (Keff). It was found that smaller fruit stones with higher surface roughness generally have higher noise reduction coefficients, and this was more pronounced for samples of 50 mm thickness. In addition, samples in the crushed form enjoyed superior sound absorption performance compared with their uncrushed counterparts. The SAC peak in the crushed form appeared at lower frequencies and its value was higher than that of the uncrushed stones. Moreover, when the air gap was introduced, all samples showed excellent sound absorption at frequencies of 400–600 Hz. It was found that, while an increase in sample thickness led to an enhancement in SAC at low and middle frequencies, the Keff values did not significantly change. Uncrushed samples demonstrated enhanced thermal insulation properties compared to their crushed counterparts. The Keff values of the specimens were found to be in the range of 0.087–0.204 W.m−1 K−1, indicating the good thermal insulation performance of the panels. The frequency-dependent SACs of fruit stone panels were predicted using the Johnson-Champox-Allard and Attenborough models, and acceptable consistency was observed.

Near-net-size porous mullite ceramics with tuneable sintering shrinkage for thermal insulation applications

The microstructure and properties of porous ceramics are severely affected by volume shrinkage during the sintering process. Therefore, reducing sintering shrinkage while maintaining the properties of porous ceramics is a serious challenge. Herein, near-net-size porous mullite ceramics with tuneable sintering shrinkage were prepared by the foam-gelcasting method using kyanite as raw material and aluminum fluoride and aluminum powders as additives through the volume expansion generated by the sintering reaction. The effects of Al powder content on the sintering shrinkage, porosity, compressive strength and thermal conductivity of porous mullite ceramics were investigated. The results show that the sintering shrinkage gradually decreases with increasing Al powder content, and expansion is even produced. When the Al powder content was 5 wt%, the sintering shrinkage of porous mullite ceramics was −0.21 %, with porosity of 84.2 %, compressive strength of 2.45 ± 0.15 MPa, and thermal conductivity of 0.19 W/(m·K) at room temperature. The results of the high-temperature fire resistance test showed that the temperature difference between the front and back sides of the sample under the flame gun reached 800 °C, indicating good thermal insulation performance. The near-net-size sintering process of porous ceramics can effectively reduce the subsequent processing cost, open new paths for their production, and broaden the application fields of porous mullite ceramics.

Lightweight polyethylene terephthalate bead foams with good interfacial adhesion and thermal insulation performance fabricated by supercritical carbon dioxide secondary foaming strategy

AbstractThis paper reported the novel supercritical carbon dioxide (scCO2) secondary foaming and molding strategy to prepare the thermal‐insulation polyethylene terephthalate (PET) bead foam part with good interfacial adhesion and high expansion ratio. The incorporation of porous structure could effectively enhance the blowing agent solubility and fabricate the system viscosity difference, which contributed to the expansion and further welding of the expanded PET beads. Under the optimum foaming conditions, PET bead foam parts with excellent comprehensive performance were successfully prepared by molding method in the confined space via scCO2 secondary foaming, and the corresponding welding mechanism of PET beads was further investigated. The obtained foam parts possessed good tensile and compressive properties, reaching 1.03 and 1.27 MPa (at 20% strain) respectively. Besides, the foam part exhibited the low thermal conductivity of 0.060 Wm−1 K−1, which confirmed the improvement of thermal insulation performance owing to the high expansion ratio.

Lightweight, Flexible, and Covalent-Bonding Phenolic Fabric Reinforced Phenolic Ablator for Thermal Insulation and Conformal Infrared Stealth.

Fiber-reinforced phenolic resin aerogel (FRPRA) composite materials are seductive candidates for high-temperature thermal protection owing to their low density, excellent thermostability, and thermal insulation. However, the intrinsic stiffness restricts their further application for high efficiency. We report a homogeneous and chemical bonding strategy for fabricating lightweight and flexible FRPRA with good ablative thermal insulation performance. The compressible (cyclic strain of 60%) and bendable (cyclic strain of 30%) abilities as well as the structural stability during ablation all benefit from the compatibility between the phenolic resin aerogel matrix and the phenolic fiber reinforcement. Additionally, low bulk density and thermal conductivity of 0.20 g cm-3 and 0.043 W m-1 K-1, respectively, endow the composite with efficient thermal insulation capability. With an 8 mm-thick coupon, the temperature of 200 °C can be decreased to 70.6 °C and the temperature around 1200 °C can be camouflaged to 78 °C through combining with the Al panel. The material also enables a conformal stealth of 600 °C based on its bendability. Hence, the composite has potential in applications of both static and dynamic thermal insulation.

A Stackelberg Game Based Optimization Method for Heterogeneous Building Aggregations in Local Energy Markets

This paper proposes an optimal operational method and a customized pricing strategy for a Microgrid (MG) incorporating heterogeneous buildings from different communities in a local energy market (LEM). A customized pricing strategy in the LEM for the heterogeneous building aggregations (BAs) is proposed considering their heterogeneous insulation performances. In this regard, a hierarchical framework with two levels for optimal decision-making of the MG as the price maker and BAs as the price takers in the LEM are presented. At the upper level, the MG aims to maximize its profit by optimizing the customized prices and its energy schedules. At the lower level, a detailed physical model of the building with adjustable heating, ventilation, and air conditioning (HVAC) systems is developed while considering the building's thermal dynamics. The objective of each BA in each community is to minimize its operating cost while ensuring the users' thermal comfort according to MG's prices. The Stackelberg game is used to model the interactions between the MG (leader) as the price maker and multiple heterogeneous BAs (followers) as the price takers in the LEM. Then, the proposed optimization model is converted into a mixed integer linear programming using the Karush-Kuhn-Tucker conditions and strong duality theorem. Numerical results show that the hierarchical method benefits both the MG and heterogeneous BAs with customized pricing schemes. The HVAC of the building with good thermal insulation performance can make more adjustments to indoor temperature to reduce its operating costs. Moreover, it has a more significant impact on MG's electricity prices.

Study on the post-fire axial compressive performance of the lightweight ceramsite foamed concrete sandwich composite shear wall

This study is carried out to develop a new lightweight ceramsite foamed concrete sandwich composite shear wall, which is a new and affordable building system. The shear wall consists of two ordinary concrete wythes and a ceramsite foamed concrete intermediate sandwich layer between the wythes. Experimental investigation on five shear wall specimens is conducted by varying the parameters such as thickness of the ordinary concrete wythes and the insulation layer, reinforcement pattern and constrained component. Besides, by conducting fire test and axial compressive load test, the results are obtained, including the apparent phenomenon after fire, crack pattern and failure modes, load capacity, load-out of plane curve, strain distribution of the composite sandwich shear wall. The results show that sandwich ceramsite foamed concrete has good thermal insulation performance, and the compositeness of wythes and sandwich layer has reached in a certain degree. However, the compositeness of specimen using truss bars is weaken in the late loading stage and truss bars are advised to be used with the horizontal tie bars in practical engineering application. Compared with other specimens, the experiment ultimate strength has been increased by approximately 75 % by arranging the constrained component on the wall. Finite Element (FE) analysis is also conducted by ABAQUS and the results shows good agreement with experiment results, indicating that the FE model can be used to predict the behavior of the sandwich composite shear wall. Based on the existing methods, a modified method to calculate ultimate compressive bearing capacity after fire is proposed, with the maximum calculation error of 19 %, which shows that all methods can be applied to the practical engineering design.

Study on post-fire resistance of ceramsite foamed concrete sandwich composite slabs

The ceramsite foamed concrete sandwich composite slab has the characteristics of light weight and good heat insulation performance. At present, there are few research on the fire resistance of ceramsite foamed concrete sandwich composite slab at home and abroad, and the damage mechanism of ceramsite foamed concrete sandwich composite slab under fire is not clear. To fill this gap, constant load-temperature rise fire test and static loading test on five slab specimens are conducted by varying the parameters such as sandwich layer thickness, reinforcement pattern, shear span ratio and construction method. Based on the test, the results are studied, including the temperature distribution and deformation characteristics under fire, load–displacement curves, crack pattern and damage mode, residual bearing capacity of the slab after fire. The results show that ceramsite foamed concrete sandwich composite slab has good thermal insulation performance, the overall working performance, flexural bearing capacity and deformation ability of the slab is mainly affected by the slip at the composite surface. The integrity of the slab and the residual bearing capacity and ductility after fire could be significantly improved by the configuration of truss rebar. It is suggested to decrease the time difference of concrete placement at the composite surface or set shear keys and truss rebar to improve the cooperative working ability between the surface layer and the sandwich layer. Moreover, Finite Element analysis is carried out by ABAQUS software and the results show good agreement with experiment results. A new compositeness degree analysis (CDA) method for calculating the residual bearing capacity of ceramsite foamed concrete sandwich composite slab after fire considering different compositeness degree is proposed, which could be used for the practical engineering design.

Preparation of Melamine Formaldehyde Foam and a Melamine-Formaldehyde-Organo-Clay Nanocomposite and Hybrid Composites

Mineral fillers can be added to thermoset polymers to improve thermal conductivity and deformation behavior, shrinkage, impact strength, dimensional stability and molding cycle time. This study aims to prepare various hybrid composites (MFHCs) using melamine formaldehyde foam (MF), a melamine formaldehyde organo-clay nanocomposite (MFNC) and also pumice as primary filler, and gypsum, kaolinite and a hollow glass sphere as secondary filler. It also focuses on the study of some mechanical properties and thermal conductivities, as well as their microscopic and spectroscopic characterization. For this, firstly, organo-clay was prepared with the solution intercalation method using montmorillonite, a cationic surfactant and long-chain hydrocarbon material, and then was produced using a melamine formaldehyde nanocomposite with in situ synthesis using a melamine formaldehyde pre-polymer and organo-clay. Finally, hybrid composites were prepared by blending various minerals and the produced nanocomposite. For morphological and textural characterization, both FTIR spectroscopy and XRD spectra, as well as SEM and HRTEM images of the raw montmorillonite (MMT), organo-montmorillonite (OMMT), pure polymer (MF) and prepared hybrid composites, were used. Spectroscopic and microscopic analyses have shown that materials with different textural arrangements and properties are obtained depending on effective adhesion interactions between polymer–clay nanocomposite particles and filler grains. Mechanical and thermal conductivity test results showed that melamine-formaldehyde-organo-clay nanocomposite foam (MFCNC) exhibited a very good thermal insulation performance despite its weak mechanical strength (λ: 0.0640 W/m K). On the other hand, among hybrid composites, it has been determined that the hybrid composite containing hollow glass beads (MFCPHHC) is a material with superior properties in terms of thermal insulation and mechanical strength (λ: 0.642 W/m K, bulk density: 0.36 g/cm3, bending strength: 228.41 Mpa, modulus of elasticity: 2.22 Mpa and screw holding resistance: 3.59 N/mm2).

Development of eco-friendly wall insulation layer utilising the wastes of the packing industry

Efficient thermal insulation materials considerably lower power consumption for heating and cooling of buildings, which in turn minimises CO2 emissions and improves indoor comfort conditions. However, the selection of suitable insulation materials is governed by several factors, such as the environmental impact, health impact, cost and durability. Additionally, the disposal of used insulation materials is a major factor that affects the selection of materials because some materials could be very toxic for humans and the environment, such as asbestos-containing materials. Therefore, there is a continuous research effort, in both industry and academia, to develop sustainable and affordable insulation materials. In this context, this work aims at utilising the packing industry wastes (cardboard) to develop an eco-friendly insulation layer, which is a biodegradable material that can be disposed of safely after use. Experimentally, wasted cardboard was collected, cleaned, and soaked in water for 24 h. Then, the wet cardboard was minced and converted into past papers, then cast in square moulds and left in a ventilated oven at 75 °C to dry before de-moulding them. The produced layers were subjected to a wide range of tests, including thermal conductivity, acoustic insulation, infrared imaging and bending resistance. The obtained results showed the developed material has a good thermal and acoustic insulation performance. Thermally, the developed material had the lowest thermal conductivity (λ) (0.039 W/m.K) compared to the studied traditional materials. Additionally, it successfully decreased the noise level from 80 to about 58 dB, which was better than the efficiency of the commercial polyisocyanurate layer. However, the bending strength of the developed material was a major drawback because the material did not resist more than 0.6 MPa compared to 2.0 MPa for the commercial polyisocyanurate and 70.0 MPa for the wood boards. Therefore, it is recommended to investigate the possibility of strengthening the new material by adding fibres or cementitious materials.

Fire-resistant polyimide-silica aerogel composite aerogels with low shrinkage, low density and high hydrophobicity for aerospace applications

Polyimide (PI)-silica aerogel composite aerogels with low shrinkage (3.7%), low density (0.061 g/cm3), low thermal conductivity (0.0216 W m−1 K−1), high hydrophobicity (146°) and good fire resistance were prepared by incorporating silica aerogel powders into PI matrix. The properties of the aerogels are affected by the type and content of silica aerogel powders. The samples show high compressibility, and the stress at 80% strain increases with the increase of silica aerogel powder content. The addition of inorganic silica aerogel powders (ISAp) can improve the thermal stability of the aerogel and the fire resistance and structural integrity of the sample under flame, but has adverse effect on moisture resistance. While the addition of polyvinylpolymethylsiloxane aerogel powders (PAp) improves the moisture resistance of the aerogel but weakens the thermal stability and fire resistance. The introduction of both ISAp and PAp can reduce the thermal conductivity of the aerogel, and the samples exhibit good thermal insulation performance. Furthermore, ground equivalent simulation tests were carried out to verify the adaptability of these aerogels in the space environment. The sample meets the standard requirements and shows stable structure and performance during the tests, which proves its potential application in the aerospace field.

Polyimide aerogels with low thermal conductivity and high-temperature stable properties prepared by lyophilization for flexible thermal protection

Polyimide aerogel, presenting an outstanding new material for lightweight protective thermal insulation, has garnered significant attention in the aerospace field. Despite its potential, due to the high production cost of the supercritical drying method used for its preparation, its widespread application is limited. In this research, a series of lightweight polyimide aerogels (F-PIAs, 3,3',4,4'-biphenyl tetracarboxylic dianhydride (s-BPDA) and 4,4'-diaminodiphenyl ether (ODA)) with excellent thermal protection properties were prepared by lyophilization. The findings indicated that F-PIAs (Freeze-dried polyimide aerogels) exhibited comparable physical characteristics to S-PIAs (Supercritical-dried polyimide aerogels), while their preparation cost was even more economical. F-PIAs exhibits excellent flexible and compression behavior (compression strength up to 1.16 MPa, modulus up to 12.8 MPa), which provide a great structural basis for the production of molded thermal insulation protective materials. The average pore diameter of F-PIAs is in the range of 7∼11 nm. The nanoporous structure leads to the gas within the pores of the aerogel producing the Knudsen effect, thereby significantly enhancing the thermal insulation performance of the aerogel. The thermal conductivity of F-PIA-4 (Freeze-dried polyimide aerogels with a solid content of 4%) at room temperature is as low as 0.023 W·m−1·K−1, which is superior to the PIAs (0.043 W·m−1·K−1) prepared by lyophilization in literature. Its thermal diffusion coefficient changes from 0.108 mm2·s−1 to 0.18 mm2·s−1 in the temperature range of 27°C to 200°C, demonstrating good thermal insulation performance at high temperatures. Meanwhile, after heating on a 150°C flat plate for 11 min and 41 s, the surface temperature of F-PIA-4 was only 36.2°C, further verifying its excellent thermal insulation performance. The results of the TGA experiment on F-PIA-4 demonstrated the high-temperature stability of aerogel (Td5% is higher than 523°C, Td10% is higher than 566°C). The exceptional properties of F-PIAs hold significant practical reference value in helping to reduce the manufacturing cost of high-performance aerogel thermal insulation materials, thereby enabling their widespread application in aerospace, military, and civil field.

Preparation of calcium silicate board from tobermorite-rich residue for energy conservation in buildings

The tobermorite-rich residue was derived from coal fly ash after alumina extraction via a hydrothermal process, which was used to prepare calcium silicate board for energy conservation in buildings. By employing a formulation comprising 94 wt% tobermorite-rich residue and 6 wt% pulp, the resultant calcium silicate board exhibited notable characteristics when subjected to a compression pressure of 20 MPa, including a bending strength of 6.75 MPa, a bulk density of 0.63 g/cm3, and a thermal conductivity of 0.14 W/(m·K). Tobermorite within the residue predominantly exhibited a fibrous morphology and formed porous aggregations, which proved advantageous in preparing calcium silicate board of high bending strength and good thermal insulation performance. Furthermore, the tobermorite retained its fibrous morphology even at elevated temperatures exceeding 650 °C, this thermal stability conferred excellent fire resistance performance upon the resulting calcium silicate board. Conclusively, the calcium silicate board prepared from tobermorite-rich residue demonstrated superior performances like good thermal insulation, exceptional fire resistance, light weight and high strength, etc., which would show great potential for use in buildings.