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Abstract: Porous silica ceramics were successfully prepared from silica spinning solution and introduced silica particles by electrospinning. After sintering, the sample was mainly composed of the introduced silica particles instead of the electrospun ceramic fibers. Therefore, the role of the introduced particles in this work was quite different from that of the introduced fillers in other electrospinning works. The porosity of the samples sintered at 1000°C and 1200°C were 62.4% and 55.6%, respectively. Furthermore, the porosity of the sintered sample can be adjusted by changing the content of the introduced silica particles. This method can be extended to prepare other porous ceramics just by changing the kinds of introduced particles. [Copyright &y& Elsevier]

Thermal protection has always been an important issue in the energy, environment and aerospace fields. Porous ceramics produced by the particle-stabilized foaming method have become a competitive material for thermal protection because of their low density and low thermal conductivity. However, the study of porous ceramics for composite systems using particle-stabilized foaming method was relatively rare. Here, silica-alumina composite porous ceramics were prepared by particle-stabilized foaming method, which was achieved by tailoring the surface charges of silica and alumina through adjustment of the pH. Porous ceramics exhibited porosity as high as 97.49% and thermal conductivity (25 °C) as low as 0.063 W m−1 K−1. The compressive strength of porous ceramics sintered at 1500 °C with a solid content of 30 wt% could reach 0.765 MPa. Based on the light weight and excellent thermal insulation properties, the composite porous ceramic could be used as a potential thermal insulation material in the spacecraft industry. [ABSTRACT FROM AUTHOR]

Abstract: Porous mullite ceramics was fabricated by a combination of electrospinning and pressure molding method. Different from the previous reports, the electrospinning in this experiment was just a method of arranging the whiskers into a non-woven structure and coating the whiskers with the TEOS; the pressure molding was used as the final forming method. The sample''s microstructure and phase compositions were investigated by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). In addition, their physical and mechanical properties were also measured. The prepared porous ceramics exhibited an interesting microstructure: The main body was built of layer-by-layer mullite whiskers with the silica as the high temperature binder, and the whiskers on each layer showed a non-woven structure. [Copyright &y& Elsevier]

Mullite fiber-based porous ceramics is one of the most commonly used high-temperature insulation materials. However, how to further reduce the thermal conductivity and improve the strength of such materials has been a challenge in the field of high-temperature insulation. In this paper, mullite micro/nano fiber-based porous ceramic was prepared by introducing mullite nanofibers into mullite microfiber-based porous ceramics and the effect of microfiber/nanofiber weight ratio on the samples properties were characterized and analyzed. Results showed that the compressive strength and high-temperature thermal insulation properties of the porous ceramics increased significantly with an increase in the nanofiber content. For the porous ceramics with similar density (about 0.50 g/cm3), the compressive strength of the sample with a microfibers/nanofibers weight ratio of 1:2 was 1.43 MPa, which was much higher than that of the porous ceramics prepared with only microfibers (0.26 MPa). Meanwhile, the backside thermal equilibrium temperature of the sample with a microfiber/nanofiber weight ratio of 1:2 at 900 °C environment was 355.8 °C, which was much lower than that of the porous ceramic prepared with only microfibers (476.5 °C). In addition, in order to investigate the temperature resistance of mullite micro/nano fiber-based porous ceramics, the sintering temperatures was increased from 1400 °C to 1500 °C. Results shows that the high-temperature thermal insulation performance of mullite micro/nano fiber-based porous ceramics with high mullite nanofiber content decays more seriously. The back-temperature test showed that the thermal equilibrium temperature of the samples with a mullite micron/nanofiber weight ratio of 1:1 in 900 °C environment increased rapidly from 386.3 °C to 454.2 °C when the sintering temperature was increased from 1400 °C to 1500 °C. The preparation of mullite micro/nanofiber-based porous ceramics provides a new strategy to improve the performance of fiber-based porous ceramics. [ABSTRACT FROM AUTHOR]

Mullite fiber-based porous ceramics is one of the most commonly used high-temperature insulation materials. However, how to further reduce the thermal conductivity and improve the strength of such materials has been a challenge in the field of high-temperature insulation. In this paper, mullite micro/nano fiber-based porous ceramic was prepared by introducing mullite nanofibers into mullite microfiber-based porous ceramics and the effect of microfiber/nanofiber weight ratio on the samples properties were characterized and analyzed. Results showed that the compressive strength and high-temperature thermal insulation properties of the porous ceramics increased significantly with an increase in the nanofiber content. For the porous ceramics with similar density (about 0.50 g/cm3), the compressive strength of the sample with a microfibers/nanofibers weight ratio of 1:2 was 1.43 MPa, which was much higher than that of the porous ceramics prepared with only microfibers (0.26 MPa). Meanwhile, the backside thermal equilibrium temperature of the sample with a microfiber/nanofiber weight ratio of 1:2 at 900 °C environment was 355.8 °C, which was much lower than that of the porous ceramic prepared with only microfibers (476.5 °C). In addition, in order to investigate the temperature resistance of mullite micro/nano fiber-based porous ceramics, the sintering temperatures was increased from 1400 °C to 1500 °C. Results shows that the high-temperature thermal insulation performance of mullite micro/nano fiber-based porous ceramics with high mullite nanofiber content decays more seriously. The back-temperature test showed that the thermal equilibrium temperature of the samples with a mullite micron/nanofiber weight ratio of 1:1 in 900 °C environment increased rapidly from 386.3 °C to 454.2 °C when the sintering temperature was increased from 1400 °C to 1500 °C. The preparation of mullite micro/nanofiber-based porous ceramics provides a new strategy to improve the performance of fiber-based porous ceramics. [ABSTRACT FROM AUTHOR]

The mechanical behaviors of single mullite fiber and binder/mullite fiber interface were experimentally investigated. The growth of the mullite grains of the fiber with the increasing calcination temperature greatly affected the tensile and compression strengths of the mullite fibers. As the calcination temperature went up from 1000 °C to 1500 °C, the average tensile strength decreased from 0.954 GPa to 0.191 GPa, and the Weibull modulus decreased from 5.1 to 1.8. The compressive strength was 50–60% of the average tensile strength under the same calcination temperature. The bonding strength of the binder/fiber interface increased with the increase of the calcination temperature. The mechanical properties and fracture mechanism of the mullite fiber-based porous ceramics with different binder contents were comprehensively analyzed based on the mechanical behavior of the single mullite fiber and the binder/fiber interface. [ABSTRACT FROM AUTHOR]

Porous alumina ceramics with inter-locked plate-like structure were successfully fabricated by the tert -butyl alcohol-based gel-casting method. The effects of Al/Si mole ratio on the structure and properties of the obtained products were investigated. The formation process of the inter-locked structure was analyzed. The products fabricated with the one-step method, in which the growth of plate-like alumina and the formation of the inter-locked structure were combined together, exhibited a high porosity of 76.21%, a compressive strength of 0.525 MPa and a low thermal conductivity of 0.495 W/mK, while the products fabricated by the two-step method after sintered at 1500 °C using the grinded powders after 700 °C heat-treatment as the starting materials possessed a relatively high compressive strength of 4.80 MPa. The obtained porous alumina ceramics were promising flexible insulant materials for the application in high-temperature field. [ABSTRACT FROM AUTHOR]

How to improve the strength of fibrous porous ceramics dramatically under the premise of no sacrificing its low density and thermal conductivity has remained a challenge in the high-temperature thermal insulation field. In this paper, a new kind of high-strength mullite fiber-based ceramics composed of interlocked porous mullite fibers was prepared by nanoemulsion electrospinning and dry pressing method. Results show that as to the porous ceramics with the same density (∼ 0.8 g/cm3), the three-dimensional skeleton structure composed of porous mullite fibers was much denser than that composed of solid mullite fibers. Therefore, porous mullite fiber-based ceramics exhibited a higher compressive strength (5.53 MPa) than that of solid mullite fiber-based ceramics (3.21 MPa). In addition, porous mullite fiber-based ceramics exhibited a superior high-temperature heat insulation property because the porous structure in fibers could reduce the radiant heat conduction. This work provides new insight into the development of high-temperature thermal insulators. [ABSTRACT FROM AUTHOR]

Porous Al 2 TiO 5 ceramics have drawn increasing attention in diverse applications owing to their low thermal expansion coefficient, and good resistance to thermal shock; however, Al 2 TiO 5 ceramics prepared in previous studies still exhibited a relatively high density, which limited their further application in the field of high-temperature thermal insulation. Herein, we reported the successful fabrication of hierarchically porous Al 2 TiO 5 ceramics with a unique three-dimensional skeleton structure formed by overlapped ceramic nanofibers. Results show that the introduction of SiO 2 into Al 2 TiO 5 nanofibers could significantly improve their thermal stability and meanwhile reduce their formation temperature. Al 2 TiO 5 nanofibers with 10 mol% SiO 2 exhibited a superior microstructure and excellent thermal stability, and were selected as the raw material in the subsequent preparation of corresponding porous ceramics. Porous Al 2 TiO 5 ceramics prepared by the freeze-gel casting exhibited a unique hierarchical pore structure with large pores originating from the sublimation of ice crystal and small pores formed by the overlapped of fibers. This unique microstructure endowed porous ceramics with an ultra-high porosity (97.59–95.59%), ultra-low thermal conductivity (0.0456–0.0754 W m−1 K−1) and excellent thermal stability. Owing to these outstanding characteristics, the resulting porous Al 2 TiO 5 ceramics are expected to be employed as the high-temperature thermal insulation material in a wide spectrum of advanced applications. [ABSTRACT FROM AUTHOR]

In recent years, the need for robust thermal protection for reusable spacecraft and vehicles has spurred strong demand for high-performance lightweight thermal insulation materials that exhibit high strength. Herein, we report silica porous ceramics prepared via the direct foaming technique with lightweight, ultra-low thermal conductivity and enhanced compressive strength. Silica particles (particle size: 500 nm and 2 μm) were used as the raw materials. The nano-sized silica particles were easily sintered, thereby improving the compressive strength of the ceramics, whereas the micro-sized silica particles maintained the pore structure integrity without deformation. The addition of nano-silica enhanced the compressive strength by 764% (from 0.039 to 0.337 MPa). In addition, the thermal conductivity of the ceramics was as low as 0.039 W m−1 K−1. Owing to these outstanding characteristics, these porous silica ceramics are expected to be employed as thermal insulation material in diverse fields, especially aerospace and space where weight is an important constraint. [ABSTRACT FROM AUTHOR]

Abstract: Porous silica ceramics with relatively high strength and novel bi-modal pore structure can be successfully fabricated via a facile tert-butyl alcohol-based gel-casting process by use of silica extracted from coal fly ash. Based on the evaporating of tert-butyl alcohol (TBA) during the drying process, the microstructure with bi-modal pores was obtained. By setting the solid loading (15wt.%) and changing the sintering temperature from 1050 to 1150°C, the porosity of the porous silica ceramics varied within the range of 70.1% and 72.4%, as the bulk density varied from 0.59 to 0.67g/cm3 and small pore sizes from 3.31 to 2.89nm. The compressive strength of sintered silica ceramics increased from 4.38MPa to 5.82MPa, which was attributed to the 3D-framework structure and the connection of silica particles. [Copyright &y& Elsevier]

Explorations in the stereolithography fabricated polymer-derived ceramics are still far from maturity. Herein, a novel preceramic slurry, which consists of a photocurable epoxy-acrylic siloxane and particle-size gradated ZrO 2 fillers, was digital light processing shaped into 3D preceramic precursors. By taking advantage of the high reactivity of in-situ formed silica from the polysiloxane, 3D-zircon product can be synthesized through the sintering reaction between the polysiloxane and ZrO 2 particles in the precursor at a low temperature. During the sintering process, ZrSiO 4 phase starts to appear at the temperature of 1200 °C. A proper particle-size distribution of the ZrO 2 filler, 20 wt% of micropartciles and 4 wt% of nanoparticles, not only endowed the ceramic slurry with a low viscosity but also increase the purity of the zircon products. Besides, the addition of sintering aid NaF can promote the sintering reaction between the polysiloxane and ZrO 2 particles while increase the crystalize degree of the 3D-zircon products. [ABSTRACT FROM AUTHOR]

• A high solid loading polysiloxane (PSO)/SiO 2 slurry had been developed and DLP printed into 3D-PSO/SiO 2 precursor. • More ceramic content can be preserved in the PSO/SiO 2 precursor through a two-step argon-air sintering process. • Si-based composite ceramics can be obtained through the two-step argon-air sintering process. • Bulk 3D-silica ceramics can be DLP fabricated from the PSO/SiO 2 slurry. • The introduction of sintering aid NaF can promote the sintering between the PSO and SiO 2 powders. Nowadays, 3D polymer-derived silicon oxycarbide ceramics (SiOC) can be fabricated by the stereolithography method successfully. However, due to their intrinsically poor ceramic content and the large thermal shrinkage during the pyrolysis, it is difficult for the bulk 3D polysiloxane precursors to be pyrolyzed into dense 3D-ceramics. Herein, the ceramic content of the photocurable polysiloxane precursors was increased by adding a large amount of SiO 2 powders into the low solid content epoxy-acrylic siloxane. After being added with proper dispersant, the viscosity of the high solid loading polysiloxane/SiO 2 slurry can reach a proper level. Bulk 3D-silica ceramics with the wall-thickness around 8 mm can be conveniently fabricated from the polysiloxane/SiO 2 slurry by stereolithography and a two-step sintering process. The addition of a proper sintering aid NaF can promote the 3D-PSO/SiO 2 precursor to be converted into dense and crack-free 3D-silica ceramics with good mechanical proprieties. [ABSTRACT FROM AUTHOR]

• Complex-shaped mullite components were DLP printed based on a hydroxysiloxane/Al 2 O 3 preceramic precursor strategy. • The introduction of hydroxysiloxane can improve the homogeneity and rheological properties of mullite slurry. • The introduction of hydroxysiloxane can reduce the sintering temperature of 3D-mullite precursor. • A sintering aid AlF 3 was employed to promote the sintering reaction between the hydroxysiloxane and the Al 2 O 3 filler. By taking advantage of the low sintering temperatures of the preceramic polymers, stereolithography printed mullite components derived from preceramic polymer precursor containing alumina particles can be sintered at low temperatures. However, due to their high specific surface, nano alumina particles are difficult to be dispersed into the photocurable polysiloxane. Herein, to prepare mullite slurry, a photosensitive hydroxysiloxane was employed as the preceramic polymer matrix while γ-Al 2 O 3 nanoparticle was added as the active filler. The introduction of photocurable hydroxysiloxane not only improved the homogeneity and rheological properties of mullite slurry but also shorted the ionic diffusion distance of Si-ion and Al-ion during the sintering process. Therefore, 3D mullite preceramic precursor stereolithography printed from hydroxysiloxane-Al 2 O 3 slurry was endowed with a low sintering temperature around 1400 °C. During the sintering process of preceramic precursor, sintering aid AlF 3 can participate in the reaction and further promote the formulation of mullite grains. [ABSTRACT FROM AUTHOR]

Aluminum borate porous ceramics are excellent candidates for high-temperature insulation applications. Current research on aluminum borate-based porous ceramics mainly focuses on porous ceramics made up of aluminum borate whiskers, whose low aspect ratio leads to a relatively dense porous structure; this results in porous ceramics with low porosity and relatively high thermal conductivity. In this study, we report the manufacturing of aluminum borate nanofibrous porous ceramics by an agar-based gel casting method using electrospun nanofibers with a high aspect ratio as the three-dimensional skeleton structure. We explored the effect of the alumina/boron oxide molar ratio on the microscopic morphology and crystal phase composition of the aluminum borate nanofibers and that of the sintering temperature on the micro and macro properties of porous ceramics based on the nanofibers. The results showed that aluminum borate nanofibers with an alumina/boron oxide molar ratio of 7:2 had the densest microscopic morphology, and the corresponding porous ceramics exhibited a higher porosity (91%) and lower thermal conductivity (0.11 W m−1 K−1) after sintering at 1200 °C than aluminum borate porous ceramics with aluminum borate whiskers as the skeleton. The successful synthesis of aluminum borate nanofibrous porous ceramics provides new insights into the development of high-temperature insulators. [ABSTRACT FROM AUTHOR]

[Display omitted] • SiBCN/SiC nanowire aerogel was prepared by a simple process. • The enhanced electromagnetic absorbing performance is achieved. • Superior thermal insulation property with low thermal conductivity is obtained. • The resulted aerogel is highly promising for defense and high-speed vehicle. Electromagnetic wave (EMW) absorption materials with lightweight and thermal insulation properties are highly sought after in aircraft and military application, because they can simultaneously resist aerodynamic heating and display EMW stealth function. Herein, a polymer-derived SiBCN/SiC nanowire composite aerogel was prepared through in-situ synthesis of SiC nanowires in SiBCN ceramic aerogel by catalyst-assisted annealing. The phase composition, nanoscale architectures, and EMW absorbing property of the as-obtained aerogels could be regulated by tuning annealing temperature. The resulting composite ceramic aerogel annealed at 1400 °C, which is composed of amorphous SiBCN, SiC nanowires, and free carbon, exhibits excellent microwave absorbing performance (minimum reflection loss of −50.1 dB and effective bandwidth of 6.4 GHz) and low thermal conductivity of 0.052 W/mK with low density (0.142 g/cm3). The superior EMW absorption capability is primarily ascribed to the improved impedance matching, multi-reflection, as well as enhanced interfacial polarization caused by SiC nanowires. Owing to the integration of EMW absorption and thermal insulation properties, the SiBCN/SiC nanowire aerogels pave the way for the construction of thermal insulation material for EMW absorption in the application of military and daily life. [ABSTRACT FROM AUTHOR]

The anisotropy of compression response and energy absorption of fiber enforced porous ceramics by directional freeze-casting have been investigated to infer the failure mechanism. An enhanced porous ceramic structured with fiber-bridging-lamellar walls was synthesized by directionally freezing nano spherical alumina suspension with different fiction of alumina microfibers. Due to the anisotropic microstructure, the mechanical properties of the freeze-casting ceramics are closely related to the orientation of the applied stress. Different orientations of loads correspond to the different deformation mechanisms under the load. The compression experiments under different orientations were carried out, and the failure mechanism was judged by the energy absorption characteristics and compression response. In contrast to traditional freeze-casting ceramics, the scaffolds supported with fiber bridges have higher mechanical properties (up to 15 MPa in compressive strength and density up to 0.76 g/cm3), and their failure behavior tends to plastic fracture, which increases toughness and availability without decreasing porosity and pore size. [ABSTRACT FROM AUTHOR]

Abstract In this study, alumina hollow sphere-based ceramics were successfully prepared using the dimethyl silicone rubber, a kind of preceramic polymer, as the forming binder. A mixture of inorganic fillers, including SnO-SiO 2 -P 2 O 5 (SSP) glass powder, boron carbide (B 4 C) powder, silicon (Si) powder and aluminum (Al) powder, were introduced into the silicone rubber to compensate for the weight loss caused by the ceramization of the silicone rubber. The green body exhibited an excellent flexibility and machinability due to the formation of the Si-O-Si polymeric network in the green sample. During the sintering process, the silicone rubber decomposed and transformed into the amorphous silica, occurring a large weight loss, while the oxidization reaction of the introduced inorganic fillers (B 4 C, Al and Si powders) could effectively compensate for this large weight loss to some content. The addition of SSP and B 4 C powders could decrease the melting point of the binder, and therefore improve the strength of the sample sintered at low temperatures (lower than 1300 °C); the addition of Si and Al powders could promote the formation of mullite phased, consequently introducing a high bonding strength between the alumina spheres. The sample with the addition of the mixed inorganic filler after sintered at 1500 °C exhibited a low density of 1.18 g/cm3, low thermal conductive of 0.83 W/mK and high compressive strength of 23.32 MPa and could be used as the high temperature thermal insulation materials in various thermal protection systems. [ABSTRACT FROM AUTHOR]

Abstract Silica sol, one of the most commonly used binders in the fabrication of fibrous porous ceramics, can diffuse as the solvent evaporates during the drying stage, leading to an uneven structure of ceramics. To prevent the diffusion of silica particles and prepare homogeneous mullite fibrous porous ceramics, propylene oxide (PO) was introduced into the fabricating procedures. The effects of solid content of silica sol and the molar ratio of PO /silica phase (PO/SiO 2) on the microstructure and physical properties of mullite fibrous porous ceramics were also investigated. The results demonstrated that PO addition strongly consolidated the mullite fibrous skeleton and helped to obtain a homogenous property, because silica phase had been consolidated in situ around the fibers during the gelation stage. Furthermore, the mullite fibrous ceramics prepared with PO addition showed an even microstructure and a much better compressive strength (1.489 MPa), compared with the ones prepared without PO addition (0.868 MPa). Finally, the solid content of silica sol showed a very strong relevance to the properties of the ceramics: the compressive strength raised from 0.731 MPa to 1.715 MPa with the solid content of silica sols increasing from 9 wt% to 18 wt%; while the molar ratio of PO/SiO 2 had little: the compressive strength was around 1.480 MPa, with the corresponding molar ratios of PO/SiO 2 ranging from 0.43 to 1.72. [ABSTRACT FROM AUTHOR]

MoSi 2 -borosilicate glass coating with MoSi 2 as emittance agent was prepared on mullite fibrous ceramics for enhanced superficial infrared radiation via an in-situ reaction method. The phase and structure evolutions during sintering were studied in detail. The infrared radiating property, impact resistance, thermal shock resistance and thermal endurance of the coating were investigated comprehensively. The results show that the coating was dense and flat, and it tightly adhered to the substrate by mechanical interlocking. During the sintering process, the low-temperature oxidation of MoSi 2 was restrained due to the package of binder phase formed below 500 °C, and the coating was fully densified via the viscous flow of molten Si. The total emissivity of the as-prepared coating was higher than 0.85 and the emissivity at low wavelength was higher than 0.9. The impact resistance was preferable attributed to the reinforced transition layer at the interface. The coating went through 30 thermal cycles between 1500 °C and 25 °C without cracking and spalling. The total emissivity declined merely by 4% after oxidation at 1500 °C for 50 h, which was influenced by the MoSi 2 content and the surface roughness of the coating. [ABSTRACT FROM AUTHOR]

A modified polymer adhesive characterized by “one-time connection at low-temperature without post-treatment” was developed for joining mullite ceramic. Without pre-calcination, the bonding strength of cured adhesive maintained above 6.5 MPa during the whole heating process and even reached 24.8 MPa at 1300 °C. After pre-calcination at 1300 °C, the adhesive obtained the optimum bonding performance as much more heat-resistant ceramics and high-temperature melting glass generated in adhesive. Its bonding strength kept about 45 MPa during test from RT to 700 °C, while the value decreased to 28.5 MPa at 1300 °C because of the melting of newly-formed glass. With increasing thermal-cycling times at 1300 °C, the value could maintain at about 35.2 MPa. [ABSTRACT FROM AUTHOR]

A modified heat-resistant polymer adhesive, which can be applied under both aerobic and anaerobic environments, was developed to bond various ceramics and composites. After curing process, as-received joints do not need subsequent processing and can keep appropriate strength within the whole heat-treatment processes. With increasing temperature, a series of reactions occurred at bonding area, thus influencing the adhesive’s performance and successively dividing the bonding mechanism into four modes: resin physical bonding, glass physical bonding, ceramic physical bonding and chemical bonding. The maximum strength of mullite joints could reach 33 MPa after heating at 1300 °C in air, while those of SiC and C/C joints were just 26 MPa and 13 MPa at 1100 °C in Ar, respectively. The finite-element and fracture analysis of these joints indicated that the failure of mullite and SiC joints only occurred at bonding layer, while that of C/C joints occurred at both bonding layer and interface. [ABSTRACT FROM AUTHOR]

A rectangular cross-section ceramic helical spring of yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) was prepared by the gel-casting process. Both the compressive curves and comprehension rebound curves were tested at room temperature and high temperature. The results showed that springs obeyed Hooke׳s Law at room temperature, as the compression resilience ratio of the samples was nearly 100% under the condition of spring׳s security and no damping loss occurred during the process. Besides, mechanical failures of springs occurred under loads around 128 N with the deformation of 10%. With increasing test temperature the maximum load-carrying capacity of the spring decreased, while the maximum deformation increased. Besides, the load–compression curve showed a yield step when the test temperature was above 800 °C. At elastic stage of spring under high temperature, the compression resilience ratio was also nearly 100%; however, the anelastic effect took place and energy loss increased with the increase in test temperature. [ABSTRACT FROM AUTHOR]

Abstract: Porous Si2N2O ceramics was synthesized by the tert-butyl alcohol-based gel-casting method at a relatively low temperature using Si3N4 and SiO2 powders as the starting materials and spodumene (LiAl(SiO3)2) as the sintering additive. Porous Si2N2O ceramics with relative high compressive strength (10.80MPa) and high porosity (65.5%) were successfully fabricated. The microstructure of porous Si2N2O after sintering at different sintering regimes was studied. The fibers observed in the pores can increase the compressive strength and the specific surface area of the sample. [Copyright &y& Elsevier]

A new practical phosphate adhesive was prepared based on aluminum and phosphate as matrix and SiO 2 and B 4 C as additives, which can be applied to join oxide and non-oxide ceramics under air and argon atmospheres. After being cured at room temperature, the as-received joints do not need subsequent processing and can keep stable shear strength within the whole heat treatment process. Its bonding effect for mullite under air was better than that for SiC under argon. The shear strength of mullite joints could be up to 14.5 MPa after treatment at 1300 °C, while that of SiC joints was about 9 MPa. [ABSTRACT FROM AUTHOR]