Increasing Sintering Temperature Research Articles

Vacuum sintering of the self-developed Chang’E-5 lunar regolith simulant

The utilization of in-situ lunar resources through the additive manufacturing of lunar regolith (LR) has attracted considerable interest. Sintering of LR is considered a promising method for lunar construction due to its high utilization rate and excellent service stability. However, numerous studies have been carried out on Apollo series LRs with similar chemical compositions in air or inert gas atmospheres. The effects of the lunar ultra-high vacuum conditions and the complex chemical composition of LRs on the sintering process require extensive investigation. In this study, a self-developed Chang’E-5 lunar regolith simulant (LRS) with a high-Fe content was used as the only raw material to investigate its potential applicability for future lunar construction in vacuum environment. The effects of sintering temperature on the microstructure, linear shrinkage, bulk density, weight loss ratio, and mechanical and thermal expansion properties were investigated. The results show that the linear shrinkage and weight loss ratio increase with increasing sintering temperature. However, the bulk density and unconfined compressive strength (USC) initially increase and then decrease, with the sample sintered at 1075℃ giving the highest bulk density of 2.10 ± 0.03 g/cm3 and a USC of 31.19 ± 1.96 MPa. This is attributed to the transformation of the sample sintered at 1090℃ into a semi-porous material with many cracks. Furthermore, the mechanism of pore and crack formation was revealed. The coefficient of thermal expansion (CET) of the sintered samples is approximately 7×10–6°C−1, which maintains a good service stability after cyclic temperature stress from room temperature up to 200°C. Both the USC and CET of the sample sintered at 1075℃ are superior to those of common terrestrial concrete materials. This indicates that the vacuum sintering process appears feasible for the production of building materials with sufficient mechanical strength and thermal durability for lunar base construction.

Polarization at the compositional interface in Nb-doped metastable TiO2-SnO2 solid solutions

Abstract Polarization architecture was incorporated into metastable Nb-doped TiO2-SnO2 to deliver electron accumulation at the localized TiO2-SnO2 compositionally fluctuating interface. Specimens were quenched from various holding temperatures to ambient temperature in air to avoid bimodal decomposition into TiO2 and SnO2 endmembers. At the lowest sintering temperature of 1,400°C, the mixed phase containing TiO2- and SnO2-rich compositions existed as an intermediate state to the single-phase solid solution. The phase boundary became more ambiguous with increasing sintering temperature, and the compositional fluctuation size reduced to single nanometers at 1,500°C. The permittivity due to the interfacial polarization, ε interface, increased steadily with increasing sintering temperature. The larger ε interface values at higher temperatures are attributed to the greater density of the compositionally fluctuating phase interface, which leads to greater electron accumulation at the energy barrier between the two semiconducting layers.

The effect of pressure and temperature on the properties of 88 W-10Ni-2Mn tungsten heavy alloy produced by cold press method

This research explored the impact of pressure and temperature to determine the optimal conditions for producing an 88 W-10Ni-2Mn tungsten heavy alloy (WHA) suitable for industrial purposes. To achieve this objective, tungsten, nickel, and manganese powders with predetermined ratios underwent wet milling in a two-step process. Subsequently, the powder mixture underwent compression at two pressures, namely 200 MPa and 250 MPa, employing the cold press method. The compressed mixture was then subjected to sintering in a tubular furnace at temperatures of 1200 °C, 1250 °C, 1350 °C, and 1400 °C. Microstructural characterization was conducted using optical and scanning electron microscopes (SEM). The findings indicated that increasing both pressure and temperature resulted in an enhancement of the sintering density in the samples. The optimum value was achieved at 1400 °C and 250 MPa, reaching 90.11 g/cm3. Furthermore, in the quenching sintering process, the carburization of 88 W-10Ni-2Mn WHA contributed to an increase in the micro hardness of the samples, reaching a maximum of 529 HV. The hardness exhibited an increase from 355 HV to 529 HV with a temperature rise from 1200 °C to 1250 °C. However, it decreased from 377 HV to 352 HV when the temperature increased from 1350 °C to 1400 °C. The increase of sintering temperature also led to slightly increases the continuity of tungsten‑tungsten due to the growth of tungsten particles. By increasing the temperature from 1350 °C to 1400 °C, ductile fracture was observed in WHA.

Achieving superior compressive strength-ductility synergy in a novel ODS-CrFeNi/AlCrFeNi heterostructured high-entropy composite

A novel high-entropy heterostructured composite (ODS-CrFeNi/AlCrFeNi) was fabricated by powder metallurgy method. The microstructure and mechanical properties of the composites with various sintering temperatures (950 °C to 1100 °C) and various addition amounts (0% to 20%) of FCC-structured reinforcing phase (ODS-CrFeNi) were investigated. The results revealed a reduction in porosity and an increase in relative density, reaching up to 99% with increasing sintering temperature. The optimal sintering temperature is 1100 °C. In the composites with the addition of 5% and 10% ODS-CrFeNi reinforced phases, spinodal decomposition (SD), forming BCC and B2 phases, takes place both in the matrix and in the reinforcing phase. As the reinforcing phase content is increased to 15% and 20%, SD occurs exclusively in the matrix while is suppressed in the reinforcing phase. The reinforcing phase consists of hard BCC structured Cr rich phases and soft FCC-structured FeNi phases, forming a gradient network structure. The composite with 15% reinforcing phase exhibits high hardness of 841 HV and compressive yield strength, ultimate strength and strain of 6960 MPa, 7690 MPa and 15.5%, respectively, which are 2.5, 2.7 and 1.9 times higher than those of the reference alloys (without reinforcing phase). The excellent strength-ductility synergy originates from the unique gradient network structure formed in the reinforcing phase, i.e. complex heterogeneous structure, which results in hetero-deformation induced (HDI) strengthening for higher strength and HDI strain hardening for higher ductility.

Sustainable Valorization of Mining Waste: Phosphate Sludge Repurposing for Advanced Ceramic Production.

Managing the vast quantities of waste constantly generated by mining activities is one of the major environmental and economic problems facing mankind today. Fluorapatite is separated from the associated gangue minerals by a series of crushing and screening, washing, and flotation processes. These processes produce a significant amount of phosphate sludge, which is stored on the mine site in drift rock and large surface ponds. One possible environmental option is to reuse it as an alternative raw material in ceramics and building materials. Consequently, two phosphate sludges from two different Moroccan towns, Youssoufia and Khouribga, were studied. Due to the complexity of these raw materials resulting from long geological processes, in-depth physical, chemical, mineralogical, and thermal characterization is required. Dry compressed powder pellets were sintered at 900°C, 1000°C, and 1100°C for 2 hours. The study focuses on the effect of sintering temperature on mineralogical transformations and ceramic properties such as apparent porosity, water absorption, and mechanical strength. At 1100°C, a slight increase in density was observed for both phosphate sludges. Water absorption was reduced by 2.51% in both sludges for pellets sintered at 1100°C compared to those sintered at 900°C. Mechanical strength improved significantly, with an increase of about 60% for samples sintered at 1100°C, recording 227N for Youssoufia sludge and 247N for Khouribga sludge. This work has provided new data on the physical, chemical, mineralogical, and thermal changes in ceramics as the sintering temperature increases. These data will be useful for the manufacture of high-value ceramics.

Enhanced fracture toughness of high entropy boride by adding SiC

The effect of SiC content (10 vol%, 20 vol% and 30 vol%) and sintering temperature (1800 °C, 1900 °C and 2000 °C) on the microstructure and mechanical properties of high entropy boride-silicon carbide (HEB-SiC) composites were systematically investigated in this work. The densification was gradually increased with the increase of SiC content and sintering temperature. More specially, the densification of HEB-30 vol% SiC composite obtained at 2000 °C was as high as 99.1%. As for the mechanical properties, the dense HEB-30S-2000 composite possessed the highest fracture toughness (5.24 MPa·m1/2) and Vickers hardness (28.5 GPa). The above significantly enhanced fracture toughness was closely pertained to the fracture modes adjusting. In details, after the addition of SiC, the branching and bridging of crack, the rupture of large SiC grain, and the deflection of crack existing near the HBE matrix and SiC particles jointly promote the improvement of fracture toughness. Besides, the Vickers hardness increased linearly with the relative density increasing. A simplified equation was established, which could effectually reflect the linear connection between the Vicker hardness and relative density (SiC content) of HEB-SiC composites. It will certainly play an important guiding role in the further development of HEB-SiC composites.

Raw material design, sintering temperature optimization and development mechanism investigation of self-foaming porous bricks with high solid waste addition

In recent years, the contradiction between the huge production of municipal sludge and industrial residue and the shortage of landfill space has driven the exploration of novel effective methods to valorize these solid wastes. In this research, blast furnace slag (BFS), municipal sewage sludge (MSS) and kaolin are combined innovatively as precursor materials to manufacture self-foaming porous bricks, and the sintering behavior of bricks under different BFS doses and sintering temperatures is deeply studied to reveal the development mechanism. The results indicate that the formation of Fe2O3-hematite during sintering leads to a reddish-brown appearance of the bricks, while the generation of CaAl2Si2O8-anorthite with lower melting points helps to enhance the vitrification process. Besides, the increase in BFS dose or sintering temperature has significant impacts on the evolution of the brick physicochemical properties. This occurs because changing the dose of BFS or sintering temperature can obviously regulate the internal morphological characteristics of bricks, such as particle consolidation, pore size and structural compactness. Among them, large-sized pores are considered as the weak areas of mechanical strength, which is also the responsibility for the worst compressive strength of bricks sintered at 1300 °C. Finally, under the optimal sintering conditions of 15 % BFS dose and 1250 °C sintering temperature, the compressive strength, water absorption, apparent porosity, bulk density and linear shrinkage of the resulting brick are 65 MPa, 0.45 %, 2.50 %, 2.34 g/cm3 and 19.56 %, respectively. Overall results demonstrate that using recycled sludge and waste slag in brick manufacturing can produce products with desired performance, providing preferable solutions for solid waste valorization and sustainable brick production.

Novel Sol-Gel Synthesis Route for Ce- and V-Doped Ba0.85Ca0.15Ti0.9Zr0.1O3 Piezoceramics.

To meet the current demand for lead-free piezoelectric ceramics, a novel sol-gel synthesis route is presented for the preparation of Ba0.85Ca0.15Ti0.9Zr0.1O3 doped with cerium (Ce = 0, 0.01, and 0.02 mol%) and vanadium (V = 0, 0.3, and 0.4 mol%). X-ray diffraction patterns reveal the formation of a perovskite phase (space group P4mm) for all samples after calcination at 800 °C and sintering at 1250, 1350, and 1450 °C, where it is proposed that both dopants occupy the B site. Sintering studies show that V doping allows the sintering temperature to be reduced to at least 1250 °C. Undoped BCZT samples sintered at the same temperature show reduced functional properties compared to V-doped samples, i.e., d33 values increase by an order of magnitude with doping. The dissipation factor tan δ decreases with increasing sintering temperature for all doping concentrations, while the Curie temperature TC increases for all V-doped samples, reaching 120 °C for high-concentration co-doped samples. All results indicate that vanadium doping can facilitate the processing of BCZT at lower sintering temperatures without compromising performance while promoting thermal property stability.

Production of glass-ceramics from fluorinated sludge: Structure, properties and leaching risk

Fluorinated sludge (FS) is a solid waste with massive discharge. To mitigate environmental pollution and optimize resource utilization, FS was employed in the fabrication of glass-ceramics. The impacts of different FS additions (40–60 wt%) and sintering temperatures (1000–1150°C) on the crystalline phase, microstructure, properties and leaching performance of glass-ceramics were discussed. Crystallization kinetics were studied to analyze the crystallization mechanism of glass-ceramics. The results showed that the predominant crystalline phases of glass-ceramics were anorthite and fluorite. The increasing sintering temperature facilitated the growth of crystals and the polymerization of glass network, resulting in improved densification. When the FS addition was 50%, sample sintered at 1100°C with a flexural strength of 47 MPa exhibited the best comprehensive performance: a density of 2.29 g/cm3, Vickers hardness of 584 HV. FS addition has resulted in an increase in the activation energy of glass-ceramic. The main pattern of crystallization was volume crystallization in glass-ceramic. The F− leaching concentration of all glass-ceramics is lower than 1 mg/L, which will not cause environmental pollution. Only when the FS addition was above 55%, there was a leaching risk for Cu and Zn in the sample due to its poor acid resistance. It is a promising way for FS to manufacture glass ceramics as a high-value construction material.

Microstructural evolution in polycrystals with faceted boundaries

Various types of grain growth behavior have been observed in polycrystals with faceted boundaries. The grain growth behavior observed in many different ceramic as well as metallic systems has been well explained by the mixed mechanism principle of grain growth and microstructural evolution. However, relatively few studies have considered repetitive grain growth in materials. To examine the generality of the microstructural evolution principle, two cases of repetitive grain growth during solid-state sintering are considered, one metallic (Ni) and one ceramic system (BaTiO3). The observed repetitive grain growth behavior with an increased sintering temperature (in the case of Ni) and sintering time (in the case of BaTiO3) supports well the generality of the mixed mechanism principle.

Utilization of fused deposition modeling in the fabrication of lattice structural Al2O3 ceramics

This study focuses on fabricating lattice structural Al2O3 ceramics with lattice infill densities ranging from 25 % to 70 % using filament-based fused deposition modeling (FDM) technology. A specialized filament for FDM printing was developed, comprising 53 vol% Al2O3 powder and ethylene vinyl acetate (EVA) as the primary binder component. The filament demonstrated excellent flexibility as assessed by a self-designed three-point bending test. The impact of lattice infill density and sintering temperature on dimensional changes, microstructure evolution, compressive strength, and strength-to-density ratio was explored. It was found that with increasing sintering temperature, the samples became more compact, resulting in higher levels of shrinkage, bulk density, and compressive strength. At a sintering temperature of 1600 °C, the sintered parts reached their maximum density through the solid-state sintering process. The sample sintered at 1600 °C with 70 % infill density exhibited the maximum compressive strength of 31.47 MPa, with a corresponding strength-to-density ratio of 20.84 MPa/g·cm−3. These findings highlight the successful fabrication of lattice structural Al2O3 with low density and high compressive strength by FDM technology.

Composition, microstructure and mechanical properties of PcBN composites with Al- Zr binder

Composition, microstructure and mechanical properties of PcBN composites with Al- Zr binder

Microstructure and properties of tungsten‐40 wt.–% copper composites fabricated by binder jet 3D printing

AbstractIn this work, the tungsten‐copper composites were fabricated by binder jet 3D printing technology. The effects of different printing layer thicknesses (50 μm to 100 μm) on the green density and green strength were investigated. Then, under the optimal layer thickness, the effects of different sintering temperatures (1300 °C to 1600 °C) on the microstructure and densification of tungsten‐40 wt.–% copper composites were studied. The experimental results showed that when the printing layer thickness was set as a lower value (50 μm), the tungsten‐40 wt.–% copper green part had the best strength and its density reached a maximum value of 60.73 %. After sintering for green parts printed with 50 μm layer thickness, the relative density, thermal conductivity and electrical conductivity of sintered parts first increased and then decreased with increasing sintering temperature. In our experiments, the tungsten‐40 wt.–% copper sample fabricated by binder jet 3D printing with a printing layer thickness of 50 μm under a sintering temperature of 1500 °C displayed the best properties, in which the relative density, thermal conductivity and electrical conductivity were 97.04 %, 228 W⋅m−1⋅K−1 and 46.5 % IACS, respectively.

Preparation, mechanical properties and strengthening mechanisms of T15 particles reinforced Cu matrix composites

High speed steel T15 particle reinforced copper matrix composites were prepared using powder metallurgy. A systematic investigation was conducted into the effects on the microstructure and mechanical properties of the composites of the sintering temperature, T15 hard particle content, and particle size. The results indicate that the grain size is efficiently refined by the addition of T15 hard particles. The decrease in grain size of 10 wt.% T15/Cu composite is from 6.87 μm to 1.34 μm at the same sintering temperature, and the grain size is proportional to both the sintering temperature and the size of hard particles. As the sintering temperature increases, the relative density and hardness of the composite gradually increase, while the yield strength initially increases and then declines. When sintered at 790 °C, the 10 wt.% T15/Cu composite achieved a maximum yield strength of 160.1 MPa, which is 178.9% and 30.6% higher than that of pure copper and 10 wt.% TiC/Cu composites, respectively. There are no visible cracks after compression, and a good balance of strength and toughness is achieved. Meanwhile, the primary contributions of strengthening mechanisms such as grain refinement, thermal expansion mismatch and load transfer to the mechanical properties of T15/Cu composites were analyzed. It is anticipated that this will establish a foundation for the preparation and application of high-performance copper matrix composites reinforced with metal particles.

Elucidating the mechanical-electrochemical interactions in single crystalline LiNi0.7Co0.1Mn0.2O2 cathode material during solid-state calcination

In recent years, the shift towards single-crystalline Ni-rich LiNixCoyMn1-x-yO2 (NCM) cathode materials has intensified the focus on temperature regulation via the solid-state method, aiming to enhance electrochemical capacity and control crystal size. This study investigates how variations in crystal size, indicative of distinct lattice structures, affect lithium ion transport during the electrochemical charging/discharging cycle. Our findings reveal mechanical degradation in NCM samples correlating with increased sintering temperatures of LiOH·H2O and NCMOH precursors, as evidenced by nanoindentation tests measuring elastic modulus and hardness. Elevated sintering temperatures were observed to facilitate nucleation and crystal growth, albeit introducing oxygen vacancies potentially detrimental to the initial Coulombic Efficiency within the NCM lattice. This degradation in both mechanical and electrochemical properties underscores the critical impact of sintering temperature on structural integrity. Our systematic analysis provides essential insights into the interplay between structural characteristics and electrochemical performance, offering compelling evidence for the optimization of sintering temperatures in the preparation of NCM cathode materials.

The Microstructure, Mechanical, and Friction-Wear Properties of Boron Carbide-Based Composites with TiB2 and SiC Formed In Situ by Reactive Spark Plasma Sintering.

The paper presents the influence of the temperature of the sintering process on the microstructure and selected properties of boron carbide/TiB2/SiC composites obtained in situ by spark plasma sintering (SPS). The homogeneous mixture of boron carbide and 5% vol. Ti5Si3 micropowders were used as the initial material. Spark plasma sintering was conducted at 1700 °C, 1800 °C, and 1900 °C for 10 min after the initial pressing at 35 MPa. The heating and cooling rate was 200 °C/min. The obtained boron carbide composites were subjected to density measurement, an analysis of the chemical and phase composition, microstructure examination, and dry friction-wear tests in ball-on-disc geometry using WC as a counterpart material. The phase compositions of the produced composites differed from the composition of the initial powder mixture. Instead of titanium silicide, two new phases appeared: TiB2 and SiC. The complete disappearance of Ti5Si3 was accompanied by a decrease in the boron carbide content of the stoichiometry formula B13C2 and an increase in the content of TiB2, while the SiC content was almost constant. The relative density of the obtained boron carbide composites, as well as their hardness and resistance to wear, increased with the sintering temperature and TiB2 content. Unfortunately, the reactions occurring during sintering did not allow us to obtain composites with high density and hardness. The relative density was 76-85.2% of the theoretical one, while the Vickers hardness was in the range of 4-12 GPa. The mechanism wear of boron carbide composites tested in friction contact with WC was abrasive. The volumetric wear rate (Wv) of composites decreased with increasing sintering temperature and TiB2 content. The average value of coefficient of friction (CoF) was in the range of 0.54-0.61, i.e., it did not differ significantly from the value for B4C sinters.

Effect of nitrogen addition on sintering behavior of high-entropy alloy CrMnFeCoNi powder

The effect of nitrogen addition on sintering behavior of high-entropy alloy CrMnFeCoNi powder has been investigated. CrMnFeCoNi alloy powders were nitrided to add nitrogen and then consolidated at three different temperatures. The microstructure of the nitrided CrMnFeCoNi alloy powders and sintered compacts was characterized using electron probe microanalysis (EPMA) system. In the compact sintered at 800 °C, a high-nitrogen-content region formed a continuous network structure around the low-nitrogen-content substrate. The hardness of the sintered compacts with nitrogen was higher than that of the compacts without nitrogen. The high-nitrogen-content region expanded into the substrate region. The Vickers hardness of the sintered compacts increased with an increase of sintering temperature up to 950 °C. Sintering at 1100 °C did not completely finish; the vacuum pressure in the sintering chamber rapidly increased because chromium nitride (CrN) decomposed. The results indicate that high-temperature sintering is ineffective for nitrogen-added CrMnFeCoNi alloy powder.

Microwave absorption, thermal and mechanical properties of amorphous nano carbon doped aluminium nitride composite ceramics

Low-cost amorphous nano-carbon (ANC) was employed as an absorbent to modify the microwave performance of AlN ceramics (AlN-4 wt% Y2O3-x wt% C, x = 0, 2.0, 3.8, 3.9, 4.0) via hot-pressing sintering, and the thermal and mechanical properties were also investigated. With the increase of ANC content from 0 to 4.0 wt%, the relative density of AlN composite decreases from 3.28 g cm−3 to 3.16 g cm−3 when sintered at 1800 °C for 2 h, and with the increase of sintering temperature from 1700 °C, the density of the 4.0 wt% ANC doped AlN composite presents trend of increase and reaches the maximum value of 3.16 g cm−3 at 1800 °C and then decreases. The XRD pattern shows that the composites are composed of AlN and Y–Al–O (YAG, YAP, YAM et al.) phases. SEM results indicate that average grain sizes for AlN and secondary phases gradually decrease with increasing carbon content, suggesting inhibited grain growth due to ANC addition. No obvious changes in phase constitution nor intensity changes were detected with the increase in carbon content and sintering temperature. As the carbon content increases from 0 to 4.0 wt%, the dielectric constant gradually increases from ∼9 to 13.89 at 10 GHz, the dielectric loss gradually increases from the vicinity of 10−3 to 0.38 at 10 GHz, and the reflective loss decreases from −27.92 dB to −49.40 dB, the thermal conductivity of the AlN-ANC composite decreases from 116.63 W m−1 K−1 to 50.13 W m−1 K−1. In addition, with 4.0 wt% ANC addition, the dielectric constant, dielectric loss, reflective loss, hardness, elastic modulus, bending strength, and fracture toughness are 13.89, 0.38, 49.40 dB, 6.4 ± 0.4 GPa, 262 GPa, 268.78 MPa, and 1.4 ± 0.1 MPa m1/2, respectively. Its ability to efficiently absorb microwave energy enhances the performance of devices including radar systems, communication equipment, and microwave heating systems, making it a promising candidate for microwave vacuum electronic applications.

Effect of sintering temperature on microstructure and electrical properties of Na0.5Bi0.47Sr0.02TiO3-δ ceramics

In this investigation, a series of Na0.5Bi0.47Sr0.02TiO3-δ samples, sintered from 1000 to 1100 °C, were synthesized utilizing the solid-state method. The XRD results indicate that all samples exhibit a perovskite phase, with the exception of those sintered at 1100 °C, which display no discernible impurity peaks. The SEM results indicate that the average grain size exhibits an increase proportionate to the sintering temperature, which attributes to the variations in the actual Na/Bi ratio. From the study of grain conductivity we can obtain that the dominant factor affecting grain conductivity is the activation energy. At 1100 °C, the oxygen vacancy concentration emerges as the primary determinant of grain conductivity. It should be noticed that the phase transition temperature of the sample increases (350 °C→400 °C) with the increase of sintering temperature, which is due to the local A-site disorder aggravated by high temperature sintering. Therefore, reducing the sintering temperature is beneficial to improve the grain conductivity. The grain boundary conductivity initially rises, then diminishes with increasing sintering temperature. It is evident that the enhanced macroscopic grain boundary conductivity stems from a marked reduction in space charge potential within the 1000–1025 °C temperature range. Within the 1050 °C−1100 °C temperature range, the space charge potential barely changed, the significant decrease of intrinsic grain boundary conductivity can be attributed to the surge in the coverage ratio of grain boundary impurities and the number of grain boundary impurities increased caused by the rapid reduction of grain boundary area and thermal evaporation. The research on electrical performance of NBT-based oxygen-ion conductors will promote the application of NBT-based oxygen ion conductors in solid oxide fuel cells, oxygen sensors and other fields.

The effect of degree of sintering on the structural and mechanical properties of Si3N4–SiO2 glass ceramics

Silica-based glass ceramics have been extensively used in biomedical applications due to their superior biocompatibility and controllable properties. However, their low mechanical strength limits their application. This could be addressed by optimizing the crystalline phase which determines their final properties. Silicon nitride has attracted attention due to its combination of good mechanical and biological properties. Therefore, to combine the advantage of silica-based glass and silicon nitride ceramic, this study developed a silicon nitride-silicon dioxide (Si3N4–SiO2) glass ceramics. The effects of spark plasma sintering parameters on the structural and mechanical properties of Si3N4–SiO2 glass ceramics were investigated. Full densification was reached at a sintering temperature of 1300 °C, a holding time of 10 min and an applied pressure of 80 MPa (relative density = 99.19 %). No silicon oxynitride (Si2N2O) crystalline phase was formed in the sintered glass ceramics, as confirmed by XRD. The interface between the β-Si3N4 crystalline and amorphous SiO2 was investigated by HRTEM, and the results indicated that an amorphous interfacial oxide was formed at the interface. The mechanical properties increased with increasing sintering temperature, as a result of the increased density. The Si3N4–SiO2 glass ceramics sintered at 1500 °C exhibited the highest value of toughness and flexural strength, at 4.6 ± 0.28 MPa m1/2 and 360 ± 27 MPa. The indentation cracks observed by SEM showed that the large β-Si3N4 grains promoted crack deflection, while the equiaxed Si3N4 grains with a lower aspect ratio led to transgranular fracture. The mechanical properties of these Si3N4–SiO2 glass ceramics are comparable to commercial glass ceramics, indicating their promising aspects in biomedical applications.