Volume Shrinkage Research Articles

Study on the shrinkage mechanism and prediction model of high-strength specified density concrete based on the internal curing micro-pump effect of MSW incineration tailings

As an effective substitute for high-strength concrete, high-strength specified density concrete can prevent and reduce the autogenous shrinkage cracking of high-strength concrete caused by low water-binder ratio or dry environment. In this paper, the early-stage shrinkage law of high-strength specified density concrete prepared from the lightweight aggregate of municipal solid waste (MSW) incineration tailings was explored through autogenous shrinkage and non-contact dry environment shrinkage tests. Combined with the tests of relative humidity, capillary negative pressure, penetration resistance, mesoporous structure and hydration products, the shrinkage reduction mechanism of internal curing micro-pump effect of incineration tailings in high-strength specified density concrete was revealed systematically and comprehensively. What’s more, the shrinkage prediction model of high-strength specified density concrete was established accordingly. The results show that replacing high-strength concrete with high-strength specified density concrete can effectively reduce the autogenous-shrinkage value by more than 68.5%, and incineration tailings can be widely used as internal curing material in cement concrete. It deserves to be mentioned that incineration tailings have significant internal curing micro-pump effect in high-strength specified density concrete. More importantly, the micro-pump water releases effect before the critical humidity point (RH = 100%) ameliorates the hydration degree of high-strength specified density concrete (SDC-25, SDC-50 and SDC-75) by 34.9%, 69.9% and 103.4%, and the self-expansion effect produced compensates for the volume shrinkage resulted from chemical shrinkage. Nevertheless, after the critical humidity point (RH < 100%), the water release effect of micro-pump lessens the pore negative pressure. The difference between the critical point test results of SDC-25, SDC-50 and SDC-75 relative humidity and the modified predicted shrinkage values of Zhang Jun-Hou Dongwei is 2.4%, 1.8% and 1.3%, respectively. The deviation between the two is within 20%, and the correlation coefficient (R2) is 0.943, which suggests that the modified Zhang Jun-Hou Dongwei model is applicable to the shrinkage prediction of high-strength specified density concrete of the shrinkage reduction type of internal curing. By adjusting the aggregate composition structure of traditional high-strength concrete and introducing internal curing micro-pump effect, it is helpful to improve the shrinkage resistance of high-strength concrete and the technical progress of the resource utilization of bulk solid wastes (incineration tailings) in cement concrete.

Effects of main drying temperature on drying characteristics and quality of freeze-dried scallion (Allium fistulosum)

The main drying link is the longest time-consuming stage in vacuum freeze-drying (VFD) technology. This study evaluated the effects of main drying temperature (constant temperature, variable temperature (VT)) on the drying characteristics and quality of scallion in VFD. The results showed that there was no significant difference between the drying time of VT and 4 °C group. However, the drying time of VT group was 48.38% shorter than that of −20 °C group. After VT-VFD, the scallion sample was brighter, the volume shrinkage and degree of tissue structure damage was lower, and the bioactives content was higher. Also, after rehydration, the VT-VFD scallion better retained its flavor than the constant temperature-VFD scallion. Therefore, VT drying can significantly improve the drying characteristics and product quality of VFD scallion.

Peripheric and central smell regions in patients with chronic rhinosinusitis with nasal polyps: An MRI evaluation

Abstract OBJECTIVE. We evaluated the effect of olfactory deficiency caused by sinonasal polyposis using a magnetic resonance imaging (MRI) evaluation. MATERIAL AND METHODS. In this retrospective study, 33 adult patients with bilateral chronic rhinosinusitis with nasal polyps (CRSwNP) (Group 1) and 30 healthy subjects without nasal polyps (Control, Group 2) were included. On coronal T2 weighted SPIR images of the MRI, the olfactory bulb (OB) volume and the olfactory sulcus (OS) depth were measured; the same action was performed on the axial T1 weighted images, for the corpus amygdala and insular gyrus areas. RESULTS. OB volume, insular gyrus and corpus amygdala areas of the CRSwNP group were significantly lower than those in the control group (p&lt;0.05). In the CRSwNP group, there were positive correlations between OB volumes, OS depths, and insular gyrus areas and corpus amygdala areas bilaterally (p&lt;0.05). In females, bilateral insular gyrus areas decreased compared to the males (p&lt;0.05). When polyp duration got longer, the right corpus amygdala area decreased (p&lt;0.05). In older patients with a CRSwNP, the left corpus amygdala area decreased (p&lt;0.05). CONCLUSION. OB volume was found to be smaller in the CRSwNP group. We think that the OB volume has decreased primarily due to decreased transfer of odor particles (sensory input) related to nasal obstruction and inflammation in the presence of nasal polyps. After OB volume shrinkage, the insular gyrus and corpus amygdala areas shrink due to the decreased data transfer to the central odor system. In patients with nasal polyps, olfactory functions may improve after endoscopic sinus surgery.

Maxillary sinus volume and mucosal thickening according to the septal deviation angle and age of the children.

We examined the relationship between nasal septal deviation (SD) angle and maxillary sinus volumes by examining the paranasal sinus computed tomography (PNSCT) images in children. In this retrospective study, PNSCT images of 106 children with one-sided nasal SD were included. According to the SD angle, two groups were identified: Group 1 (n = 54): SD angle ≤ 11°, Group 2 (n = 52): SD angle > 11°. There were 23 children between 9 and 14 years and 83 children between 15 and 17 years. Maxillary sinus volume and mucosal thickening were evaluated. In 15- to 17-year age group, maxillary sinus volumes of males were higher than females bilaterally. For each of the males and females, ipsilateral maxillary sinus volume was significantly lower than the contralateral side in all children and in 15- to 17-year age group. In each of the SD angle values (≤11 or >11) separately, ipsilateral maxillary sinus volume was lower; and in the SD angle > 11° group, maxillary sinus mucosal thickening values were higher than those of the contralateral side. In young children in 9- to 14-year age group, bilateral maxillary sinus volumes decreased, in this group maxillary sinus volume was not affected according to the SD. However, in 15- to 17-year age groups, maxillary sinus volume was lower on the ipsilateral SD side; and ipsilateral and contralateral maxillary sinus volumes of the males were significantly higher than those in the females. SD should be treated at an appropriate time to prevent SD-related maxillary sinus volume shrinkage and rhinosinusitis.

Preparation and characterization of carbon block with coal tar pitch and phenolic resin as mixed binder

Here we present a method to prepare carbon block with excellent mechanical strength by using coal tar pitch and thermoplastic phenolic resin as a mixed binder and hexamethylene tetramine as a crosslinker. The effect of phenolic resin content in the mixed binder on properties of carbon blocks was investigated. In addition, the viscosity and fluidity of the mixed binder before and after crosslinking, and the evolution of size and pore structure of the carbon block during carbonization were systematically explored. The results revealed that the mixed binder had both low viscosity in the mixing stage and low fluidity in the carbonization stage. The low viscosity was favorable for its mixing with the pitch coke. Compared to carbon blocks with coal tar pitch binder, those with mixed binder had higher volume shrinkage during carbonization, especially the strong shrinkage at 700 °C which led to the large pore closure. The density, flexural, and compressive strength of the carbon block obtained by the mixed binder reached 1.56 g·cm−3, 34.4 MPa, and 131.3 MPa, while those of carbon blocks with the single binder were only 1.35 g·cm−3, 17.2 MPa, and 33.7 MPa.

Performance evaluation for Ag and Au nanoparticle containing K 2 O‐MgO‐B 2 O 3 ‐Al 2 O 3 ‐SiO 2 ‐F glass sealants for SOFC application

Performance evaluation for Ag and Au nanoparticle containing K ₂ O‐MgO‐B ₂ O ₃ ‐Al ₂ O ₃ ‐SiO ₂ ‐F glass sealants for SOFC application

Eliminating cracking morphology of solution-processed CZTSSe absorbers by Sn-rich composition engineering

Sol-gel method has attracted widespread attention for fabricating highly efficient Cu2ZnSn(S, Se)4 (CZTSSe) solar cells. However, the volume shrinkage of the gel during the baking process will cause severe cracking of CZTSSe films, which results in shunt paths and significantly deteriorates device performance. Herein, an Sn-rich CZTS precursor is proposed to produce high-quality CZTSSe films, which could relieve the shrinkage forces in CZTS precursor film and compensate for Sn loss of CZTSSe absorbers during selenization process. The effects of Sn content on CZTS precursor compactness and the post-selenization process on the crystallization quality of CZTSSe films are thoroughly investigated. Furthermore, the formation of the MoSe2 interfacial layer and the SnSe2 secondary phase can be regulated efficiently. As a result, the separation and collection of carriers are greatly improved as the depletion region width (Wd) of the CZTSSe solar cell is broadened. And the difference between the activation energy (Ea) and band gap (Eg) has decreased, indicating that the carrier recombination loss caused by the deviated Sn content in CZTSSe films has been effectively reduced. Consequently, the efficiency of the CZTSSe device increased from 7.6% to 9.3% through Sn-rich composition engineering. This study elucidates the role of Sn content in the fabrication of high-quality CZTSSe films and advances the development of ambient air-processed CZTSSe solar cells.

Evaluation of porosity, mechanical and thermal properties of self-ignition coal gangue-based foams via fast microwave foaming

Recently, the large-scale stock and pollution of solid waste has become a serious environmental and economic problem. Upcycling the solid waste to produce porous materials is a value-added waste management method. Self-ignition coal gangue-based alkali-activated foams were successfully produced via a fast microwave foaming method within a few minutes. The effect of alkali concentration on pore structure, porosity, mechanical and thermal properties of alkali-activated foams was explored. Alkali-activated foams with low bulk density (0.41–0.81 g/cm3), high total porosity (65.6–83.5 vol%), acceptable compressive strength (0.92–4.42 MPa), and low thermal conductivity (0.11–0.14 W/mK) were obtained by a fast microwave foaming method. The foams showed excellent high temperature performance. The compressive strength showed an increasing trend after heat treatment from 500 to 1100 °C. Simultaneously, a low high-temperature volume shrinkage (4.0–4.1%) was achieved. The obtained foams can be used as high-performance proppant materials, thermal insulation building materials, and in fire-resistant applications.

Superior tensile and recovery properties of hydride-dehydride elemental NiTi alloys homogenized using high-temperature sintering

Elemental powder (EP) sintering is attractive for use in fabricating the NiTi shape memory alloys due to its low cost and compositional flexibility. However, because of sintering challenges that are not adequately resolved, current EP NiTi alloys exhibit zero or trace tensile properties. In this study, a 10−4 Pa vacuum system was used to optimize the sintering of EP NiTi alloys. The unavoidable liquid phase and high-temperature sintering promoted elemental homogenization, which substantially improved the engineering properties of EP NiTi. Compared to previous studies, increasing the vacuum level caused deflagration reactions at a low temperature of 700 °C. It also rendered the materials more susceptible to macroscopic millimeter-scale defects at > 1050 °C due to the loss of the liquid phase. These problems could be avoided by optimizing the sintering process and completing high-temperature sintering at 1250 °C. High-temperature sintering promoted local elemental homogenization rather than extensive elemental migration. 3D–Computed Tomography reconstruction revealed that high-temperature sintering promoted shrinkage of the pore volumes and homogeneity of pore size distribution. This sintering process considerably improved the mechanical properties of the EP NiTi alloy. The tensile strength and related elongation were 701–763 MPa and 16.54–21.97%, respectively, and the alloy exhibited a shape memory of >90% in an 8% tensile evaluation. This optimization strategy, which integrates impurity control and the intermetallic phase sequence, promotes the practical applications of EP NiTi alloys.

Synthesis and Property of an Organosilicon Polyurethane Acrylate Prepolymer Containing Disulfide Bonds for Photopolymerization

AbstractPhotocurable organosilicon polyurethane acrylate materials combine the merits of both polyurethane and organosilicon and have become the most widely used class of photocurable resins due to the advantages of easy preparation and performance tunability, but they suffer from serious volume shrinkage and difficult degradation. In this article, an organosilicon polyurethane acrylate prepolymer (SSiPUA) containing disulfide bonds is designed and synthesized. The prepolymer exhibits good ability to photopolymerize and reduce the volume shrinkage. The final double bond conversion (DBC) of the system with SSiPUA reaches 92%, and the volume shrinkage is decreased to 4.9% that is much less than that (13.9%) without SSiPUA. Besides, with the increase of SSiPUA content within a certain range, the hydrophobicity, heat resistance, the tensile strength, and the elongation at break of the photocured films gradually increase. The water contact angle, initial decomposition temperature, the tensile strength, and the elongation at break reach up to 93°, 282 °C, 1.8 MPa, and 576.2%, respectively. However, the glass transition temperature is reduced with the increase of SSiPUA content owing to the excellent flexibility of polysiloxane chain segments. More significantly, the SSiPUA containing disulfide bonds endows the photocured film with good degradation properties.

Multiple overlapping MW ablation in benign thyroid nodule: single-center 24-month study.

This study aimed to evaluate the safety and long-term efficacy using the multiple overlapping ablation technique with a novel non-cooled microwave system in benign symptomatic thyroid nodules. This prospective cohort single-center study collected complication data from the start of the procedure to 30 days postoperatively and evaluated the safety and effectiveness with a follow-up of 24 months. Ultrasound examinations were performed to determine the volume shrinkage during follow-up. Thyroid function, cosmetic and symptoms scores, and satisfaction degree were evaluated. A total of 30 symptomatic benign thyroid nodules were treated by microwave ablation using a power between 15 and 30 watts depending on the size of the nodule to be treated. The volume reduction rates in months 1, 3, 6, 9, 12, and 24 after ablation were 32%, 59%, 67%, 69%, 73%, and 81%, respectively. The mean symptom score and mean cosmetic score before treatment were 4 and 3 respectively, while after treatment they dropped to 3 and 1 respectively. Thyroid function indicators fluctuated in the normal range, and those with hyperthyroidism recovered to normal parameters. One case of temporary laryngeal paralysis occurred postoperatively and fully recovered in less than 3 months. The novel microwave ablation system presented herein can help achieve good clinical success rate in benign thyroid nodules, with a satisfying safety profile. The microwave ablation performed with the multiple overlapping ablation technique could be a good alternative to surgery and radiofrequency ablation in the management of benign thyroid nodules.

Conversion surgery for advanced hepatocellular carcinoma after combination treatment of lenvatinib and camrelizumab: a case report

BackgroundHepatocellular carcinoma (HCC) is an aggressive malignancy with high morbidity and mortality. Conversion therapy can improve surgical resection rate and prolong survival time for patients with advanced HCC. We show that combination therapy with lenvatinib and camrelizumab is a novel approach to downstage unresectable HCC.Case presentationA 49-year-old man was diagnosed with massive HCC with hilar lymph node and lung metastases. Since radical resection was not feasible, lenvatinib and camrelizumab were administered as first-line therapy. After 10 cycles of camrelizumab and continuous oral administration of lenvatinib, the tumor exhibited striking shrinkage in volume indicating a partial radiological response, accompanied by a reduction in the alpha-fetoprotein levels, followed by salvage resection. Intriguingly, an improvement in predictive biomarkers, like lactate dehydrogenase (LDH) and neutrophil-to-lymphocyte ratio (NLR), was observed. Notably, the pathological examination found high levels of necrosis in the resected tumor, and flow cytometry analysis indicated a significant increase in the ratio of CD5+ and CD5− B lymphocytes in the peripheral blood. After the treatment, the overall survival period was over 24 months, and no recurrence was observed 17-month post-surgery.ConclusionsA combination of lenvatinib and camrelizumab may be a new conversion therapy for initially unresectable HCC to resectable HCC, thus contributing to improve the disease prognosis. In addition, the combination regimen could cause an activated immune response, and LDH, NLR, and CD5+ B-cell levels might be predictors for immunotherapy efficacy.

Preparation of alumina/silica/exfoliated graphite nanoplatelets composite aerogels and its application as supporting material for erythritol based form-stable phase change materials

Alumina-silica (Al-Si) and Al-Si/exfoliated graphite nanoplatelets (xGnPs) composite aerogels were prepared via a novel epoxide method followed by ambient pressure drying (APD) and heat treatment. Epichlorohydrin (ECH) was applied as proton scavenger to control the hydrolysis of AlCl3·6H2O to obtain the composite gel. Then the ring-opening products of ECH acted as drying control chemical additives to prevent the gel from high volume shrinkage during APD and was then removed by heat treatment at 800 °C to obtain composite aerogels. Doping the Al-Si aerogel with xGnPs was in favor of obtaining composite aerogels with high specific area and low volume shrinkage. The specific surface area of the prepared Al-Si/xGnP aerogels could attain 350 m2/g with a pore volume of 1.156 cm3/g. The synthesized aerogels were then vacuum infiltrated with erythritol (ET) to obtain form-stable phase change materials (FSPCMs). The loading of ET in the prepared FSPCMs attained 90 wt%, and the latent heat storage capacity attained 279 J/g. In addition, the thermal conductivity of the FSPCMs could be enhanced to 49.8 % higher than pristine ET with the help of 0.6 wt% xGnPs, and the supercooling of ET in the FSPCMs could be suppressed to 59 °C. Moreover, the FSPCMs supported by Al-Si/xGnP aerogels possessed greatly enhanced light-to-thermal conversion efficiency than the pristine ET and the Al-Si aerogel supported FSPCM. More importantly, the FSPCMs possessed very good long-term thermal reliability.

Modified Supporting Materials to Fabricate Form Stable Phase Change Material with High Thermal Energy Storage.

Thermal energy storage (TES) is vital to the absorption and release of plenty of external heat for various applications. For such storage, phase change material (PCM) has been considered as a sustainable energy material that can be integrated into a power generator. However, pure PCM has a leakage problem during the phase transition process, and we should fabricate a form stable PCM composite using some supporting materials. To prevent the leakage problem during the phase transition process, two different methods, microencapsulation and 3D porous infiltration, were used to fabricate PCM composites in this work. It was found that both microsphere and 3D porous aerogel supported PCM composites maintained their initial solid state without any leakage during the melting process. Compared with the microencapsulated PCM composite, the 3D porous aerogel supported PCM exhibited a relatively high weight fraction of working material due to its high porosity. In addition, the cross-linked graphene aerogel (GCA) could reduce volume shrinkage effectively during the infiltration process, and the GCA supported PCM composite kept a high latent heat (∆H) and form stability.

In Situ Growth of ZIF-8 onto Aramid Nanofiber Composite Aerogel for Efficient Removal of Pollutants in Water

The public health and water ecosystems are affected by industrial wastewater, resulting in water pollution including heavy metal ions and organic matter, so that adsorbents with multiple adsorption effects are developed to achieve efficient adsorption. In this work, the porous zeolitic imidazolate framework-8 (ZIF-8) was assembled onto cellulose nanofiber (CNF)/poly(vinyl alcohol) (PVA)/aramid nanofiber (ANF) composites and the ZIF-8@CNF/PVA/ANF (ZIF-8@CPA) composite aerogel was designed and fabricated. The composite aerogel has good physical properties and optimal adsorption performance assembled with 20% ZIF-8 content. The ZIF8-20@CPA composite aerogel has high porosity of about 99.62%; the specific surface area is 120.53 m2/g, and pore size is as low as 11.82 μm with a lower volume shrinkage of 1.31%. The adsorption capacity of Cr6+ and rhodamine B about lightweight ZIF8-20@CPA composite aerogels reached 231 mg/g and 201 mg/g, respectively. Due to the 3D porous structure, electrostatic interaction, and ion synergism generated by its assembly with ZIF-8, the composite aerogels have good adsorption performance for heavy metal ions and conform to the relationship of a pseudo-second-order kinetic model. Thus, this study suggests a route to fulfill the multiple adsorbents.

Phase-Changing Polymer Film for Smart Windows with Highly Adaptive Solar Modulation.

Adjusting sunlight and thermal radiation from windows is important in efficient energy-saving applications. A high solar modulation (ΔTsol) capability as well as a high luminous transmittance (Tlum) are the ultimate aim of smart windows. In this study, hydroxypropyl cellulose (HPC), W-doped VO2, and poly-N-iso-propylacrylamide (PNIPAm) composite hydrogel films were produced. The sample was prepared between two glasses to constitute a smart window with a sandwich construction structure, which exhibits a high Tlum of 87.16%, a ΔTsol of 65.71%, and a lower critical solution temperature (LCST) of 29 °C. The practical applications of conventional PNIPAm hydrogels are limited by the volume contraction of phase transition. Here, this challenge is addressed by the simple method of combining with HPC. The PNIPAm-2.5 wt % HPC hydrogels possess thermo-responsive contractility with a volume shrinkage rate of 8.5%. Even after 100 high- and low-temperature cyclic durability tests, the smart windows still exhibit a high solar modulation capability.

ZnTe/rGO Composite as the Fully Zinced Conversion-Type Cathodes for Aqueous Zinc Ion Batteries.

Conversion-type cathodes for aqueous zinc ion batteries (ZIBs) can provide flat plateau slop and stable output potential, compared to general intercalation-type cathodes. The high volumetric capacity and stable output potential of Te make it a promising cathode for ZIBs, but sluggish kinetics and large volume change hinder its further application. To address these issues, we revisit fully zinced ZnTe and construct ZnTe/rGO composites as the new conversion-type cathode. The electrode undergoes a solid-to-solid conversion reaction and shows a stable output potential with ultra-flat discharge plateau slop of 0.09 V (Ah g-1 )-1 . When ZnTe is de-zinced and transformed to Te during charge process, it has a volume shrinkage which generates empty space in graphene matrix for latter volume expansion of Te. The graphene matrix also improves conductivity and reaction kinetics of the cathode. Due to the combination of pre-zincation of ZnTe, graphene matrix and the elimination of "shuttle effects" process, ZnTe/rGO electrode exhibits a high and stable capacity of 186 mAh g-1 at 500 mA g-1 after 300 cycling, with almost no decay after initial 10 cycles.

Polar–Nonpolar Transition-Type Negative Thermal Expansion with 11.1% Volume Shrinkage by Design

Chemical substitution for the tuning of the working temperature of phase-transition-type negative thermal expansion (NTE) materials generally reduces the volume shrinkage during the transition. We have investigated the effects of electron doping and reduction of 6s2 lone-pair activity in PbVO3 with a large polar distortion (c/a = 1.23) and found that the combination of Bi and Sr substitutions for Pb enables a temperature-induced polar to non-polar transition with 11% volume shrinkage, even larger than the pressure-induced volume collapse of PbVO3 (∼10.6%), and is the largest value among the NTE materials reported so far. The domain structure of the coexisting cubic and tetragonal phases with such a huge volume difference was successfully observed by high-angle annular dark-field scanning transmission electron microscopy and the spatial distribution of domains by Bragg coherent X-ray diffraction imaging. The temperature hysteresis is reduced by repeated heating/cooling cycles, suggesting that the changes in the domain structure dominate the NTE properties.

Multi-Objective Optimization of Liquid Silica Array Lenses Based on Latin Hypercube Sampling and Constrained Generative Inverse Design Networks.

Injection molding process parameters have a great impact on plastic production quality, manufacturing cost, and molding efficiency. This study proposes to apply the method of Latin hypercube sampling, and to combine the response surface model and "Constraint Generation Inverse Design Network (CGIDN)" to achieve multi-objective optimization of the injection process, shorten the time to find the optimal process parameters, and improve the production efficiency of plastic parts. Taking the LSR lens array of automotive LED lights as the research object, the residual stress and volume shrinkage were taken as the optimization objectives, and the filling time, melt temperature, maturation time, and maturation pressure were taken as the influencing factors to obtain the optimization target values, and the response surface models between the volume shrinkage rate and the influencing factors were established. Based on the "Constraint-Generated Inverse Design Network", the optimization was independently sought within the set parameters to obtain the optimal combination of process parameters to meet the injection molding quality of plastic parts. The results showed that the optimal residual stress value and volume shrinkage rate were 11.96 MPa and 4.88%, respectively, in the data set of 20 Latin test samples obtained based on Latin hypercube sampling, and the optimal residual stress value and volume shrinkage rate were 8.47 MPa and 2.83%, respectively, after optimization by the CGIDN method. The optimal process parameters obtained by CGIDN optimization were a melt temperature of 30 °C, filling time of 2.5 s, maturation pressure of 40 MPa, and maturation time of 15 s. The optimization results were obvious and showed the feasibility of the data-driven injection molding process optimization method based on the combination of Latin hypercube sampling and CGIDN.

Microstructure, mechanical, wave-transparent and heat insulation properties of Si3N4 foam ceramic by organic foam impregnation combined with CVI

An ultralight and high-strength Silicon nitride (Si3N4) foam ceramic with highly efficient wave-transparent and heat insulation properties was successfully prepared using the organic foam impregnation technique combined with chemical vapor infiltration (CVI) process. The microstructure of Si3N4 foam ceramic inherits the pore structure characteristics of the template, and the ceramic skeleton is formed by coupling the Si3N4 whiskers with the CVI Si3N4 matrix. The use of CVI process avoids the volume shrinkage problem during the ceramic formation process by traditional sintering method at high temperature, and ensures the near-net-shape preparation of ceramic. Meanwhile, CVI Si3N4 matrix has pure components without impurities like low melting point metal oxides by sintering method or free carbon by polymer-derived ceramic method, which is beneficial to the improvement of wave-transparent ability and thermal stability. The addition of whisker reinforcement greatly increases the compressive strength of ceramic through whisker pulling out, crack deflection and other strengthening and toughening mechanisms. Moreover, we discuss in detail the relationship between the structural parameters of Si3N4 foam ceramic, such as whiskers-matrix solid content ratio, open-closed porosity ratio, pore size and mechanical, wave-transparent as well as heat insulation properties. In this study, the compressive strength of 40PPI Si3N4 foam ceramic with total porosity of 91.97% is 1.06 MPa, the thermal conductivity is only 0.624 W/(m·K) at 25 °C and the dielectric constant and loss tangent are 1.40 (10 GHz) and 6.35 × 10−3 (10 GHz), respectively.