Si3N4 Composites Research Articles

Effects of Diamond on the Mechanical Properties and Thermal Conductivity of Si3N4 Composites Fabricated Using Spark Plasma Sintering

Effects of Diamond on the Mechanical Properties and Thermal Conductivity of Si3N4 Composites Fabricated Using Spark Plasma Sintering

The effect of oxygen vacancies on the optical and thermophysical properties of (1-x)Si3N4 – xAl2O3 ceramics

Interest in composite ceramics based on silicon nitride (Si3N4) and aluminum oxide (Al2O3) is due to the possibility of using them as semiconductor applications associated with their operation under conditions of external influences, including heating. The paper presents the results of assessing the influence of variations in the phase composition of (1-x)Si3N4 – xAl2O3 ceramics on alterations in optical and thermophysical parameters, as well as their relationships. Analysis of the optical characteristics of the ceramics under study showed that changes in the phase composition associated with the dominance of the Al2O3 phase in the composition of the ceramics lead to a change in covalent bonds and an increase in the number of ionic bonds, which also affects the change in the semiconductor nature of the ceramics, and therefore, a change in the thermophysical properties. According to the assessment of changes in the thermal conductivity coefficient of the studied ceramics, with the dominance of the Al2O3 phase in the composition, the observed growth in the concentration of structural defects, as well as oxygen vacancies, results in the thermal conductivity coefficient decrease, as well as an elevation in the thermal expansion of ceramics during thermal heating. It has been determined that the presence of a combination of Al2(SiO4)O and Si3N4 phases in the ceramic composition leads to an increase in the thermal conductivity coefficient, as well as maintaining its stability over a wide temperature range.

Characterization of silane-treated wheat husk biomass Si3N4 and castor stem sheath fibre-epoxy composite

Characterization of silane-treated wheat husk biomass Si3N4 and castor stem sheath fibre-epoxy composite

Predicting hardness of graphene-added Si3N4 using machine learning: A data-driven approach

This study presents a data-driven framework based on machine learning (ML) using extreme gradient boosting (XGBoost) for predicting the hardness of silicon nitride (Si3N4) ceramics reinforced with graphene. The XGBoost model takes into account various factors such as graphene type and content, characteristics of the raw Si3N4 powder, the parameters of the sintering process (sintering technique, temperature, pressure, holding time), and the characteristics of the sintered samples, i.e., the density, αβ content and Vickers hardness. The parameters that influence the Si3N4 hardness most strongly are identified, with sintering pressure, sintering time and density being the most influential. The addition of graphene content up to a certain threshold (1 wt%) has a positive impact on hardness. However, beyond that it leads to a lower density and a lower mechanical performance. Sintering parameters, particularly the sintering pressure, temperature, holding time and technique, strongly affect the density, final grain size, αβ Si3N4 composition and subsequently the hardness. The study highlights the importance of density and the densification process in achieving high hardness in Si3N4 ceramics. The developed ML model provides a valuable tool for predicting the hardness of Si3N4+graphene ceramics composites and offers insights into selecting suitable graphene type, content, and processing parameters. While the study primarily focuses on Si3N4+graphene composites, this novel approach holds promise for the in-silico design and analysis of diverse ceramic materials.

Hot-pressing-oriented graphene in Si3N4 composites for enhanced electromagnetic wave absorption in X and Ku bands

In this study, the oriented graphene within graphene/Si3N4 composites was successfully achieved by two-step hot-press sintering. Microstructure analysis revealed that the graphene sheets were well dispersed in the Si3N4 matrix and oriented perpendicular to the applied stress. The composites exhibited effective electromagnetic wave (EMW) absorption capabilities and good mechanical properties. The effective absorption bandwidth (EAB) was 9.63 GHz, nearly covering the entire X and Ku bands (8.2–18 GHz), and the minimum reflect loss (RL) was −24.23 dB when the graphene content reached 7 wt% at a thickness of 2.02 mm. Meanwhile, the oriented graphene/Si3N4 composites demonstrated a bending strength of 576.66 MPa and a fracture toughness of 8.40 MPa·m1/2. The EMW absorption in these composites should be primarily due to polarization relaxation loss and conductivity loss, and the toughening mechanism should involve the graphene pull-out, crack bridging, and crack deflection. The graphene/Si3N4 composites have a promising application in structurally integrated functional materials.

Densification mechanism and microstructural evolution of Si3N4 composites with CeO2 as additives during spark plasma sintering

The densification mechanism of CeO2 doped Si3N4 ceramics during spark plasma sintering (SPS) was investigated. The sintering process was observed to undergo significant densification at the intermediate stage of sintering (1435 °C–1816 °C), and the density and grain size of CeO2 doped Si3N4 ceramic were found to be greater than those of pure Si3N4 ceramic under the same sintering conditions. To determine the densification mechanism, a creep model was utilized to determine the densification mechanism which could be interpreted based on the values of the stress exponent (n) and the apparent activation energy (Q d). The results revealed that the Q d of pure Si3N4 (381.15 kJ mol−1) is higher than that of Si3N4-CeO2 powder (265.61 kJ mol−1). Moreover, the stress exponent n of Si3N4-CeO2 powder (1.12–1.33) was higher than that of pure Si3N4 powder (1.00–1.18). This can be attributed to the fact that the addition of CeO2 resulted in the formation of a liquid phase at the grain boundary which leading to a shift in the controlling mechanism from grain boundary diffusion to grain boundary sliding.

Preparation of Si3N4 ceramic aerogel by foam-gelcasting combined concerted catalysis nitridation method

High-performance Si3N4 ceramic aerogel (CA) prepared by employing commercial Si powders containing impurity Fe as raw materials and Fe powders as catalyst through a simply Fe-concerted catalyzed nitridation technology, CS Si3N4 CAs, were synthesized at 1473 K for 5 h, and thoroughly characterized. It exhibited a porosity of 87.7 %, a compressive strength of 3.3 MPa and a specific strength of 8.7 MPa cm3 g−1, along with its outstanding low thermal conductivity (as low as 0.108 W m−1 K−1 at 373 K). Compared with the Si3N4 CA catalysis nitridation of concerted reactions by Fe(NO3)3·9H2O and in-situ catalytic nitridation by impurity Fe in commercial Si, and the specific strength of CS Si3N4 CA was about 14 % and 22 % higher than that of the former, respectively. This demonstrated that it may be more conducive to the preparation of Si3N4 CAs with high performance via catalysis nitridation of concerted reactions by Fe than Fe(NO3)3·9H2O. This work also provides an ideal method for the cost-effectiveness synthesis of high-performance Si3N4 and/or Si3N4 composites.

Microstructural evolution and investigation of mechanical properties of Al 7055 –Nano Si3N4 composites

In this paper an attempt has been made to develop the aluminium based metal matrix composites. Al7055 were chosen as base material and hard ceramic particulate nano silicon nitride as reinforcement. The composites were fabricated by using bottom pouring stir casting technique by varying weight percentage of Si3N4 in steps of (3 wt%, 6 wt% & 9 wt%) respectively and particle size of 30, 60 and 90nm. Morphological characterization of composites was conducted by using HRFESEM. The SEM result reveals that there is homogeneous distribution between the matrix and reinforcement. EDS mapping for prepared composites were done to identify the presence of alloying elements and phase distribution. XRD analysis is conducted for validation of the structural composition. Mechanical tests like tensile, micro Vickers hardness and impact test were performed on developed composites. The ultimate tensile strength of the composites at 9 wt% and particle size of 90 nm found to be diminishing due to severe agglomeration. The hardness value increases at 9 wt% and particle size of 30 nm. The toughness of the composites increased at 30 nm reinforcement size and 6 wt% as compared to higher weight percentage developed composites. Corrosion test were conducted as per ASTM G31 by weight loss method for different samples by dipping composite samples in 50 g Hcl solution for duration of 6 h and it was found that the corrosion resistance of the composites was higher while increasing the wt% of Si3N4 as compared to base matrix..

Wear-Resistant Coatings Produced from TiN–TiB2 and TiN–Si3N4 Composites by Electrospark Deposition and Laser Processing

Wear-Resistant Coatings Produced from TiN–TiB2 and TiN–Si3N4 Composites by Electrospark Deposition and Laser Processing

Preparation and investigation of mechanical and electromagnetic wave absorption properties of TiC–TiB2/Si3N4 composites

AbstractThe aim of achieving integration of lightweight, high strength, high‐temperature resistant, and satisfactory electromagnetic (EM) wave absorption was successfully accomplished in the present study by synthesizing TiC–TiB2 fibers reinforced Si3N4 composites, which were pressureless sintered at 1650°C for 2 h. The preparation of TiC–TiB2 fibers was conducted through a chloride‐assisted carbothermic method. This work focused on investigating the effects of incorporating TiC–TiB2 fibers on the mechanical properties and EM wave absorption characteristics of the composites. The 30 wt% TiC–TiB2/Si3N4 composite displayed the bulk density of 1.89 g/cm3, bending strength of 93.11 ± 3.91 MPa, fracture toughness of 1.81 ± 0.10 MPa m1/2, minimum reflection loss of −38.87 dB, and effective absorption bandwidth of 1.43 GHz in the Ku‐band, respectively. The as‐synthesized TiC–TiB2/Si3N4 composites are promising candidates for EM wave absorbing load‐bearing materials due to their outstanding mechanical properties and microwave absorption properties.

Synthesis and characterization of onion-like carbon /TiN0.3 enhanced Si3N4 composites

Research on how to obtain Si3N4 composites with high hardness and toughness at lower temperatures is important. Si3N4 composites with onion-like carbon (OLC)-TiN0.3 were prepared using high pressure and high temperature techniques. The effects of TiN0.3 and OLC additives on the mechanical properties and microstructure of the silicon nitride ceramics were analyzed. During the sintering process, the vacancies in TiN0.3 promoted the formation of the TiC0·3N0.7 interface between the three compositions, whose particles were homogeneously dispersed in the silicon nitride matrix with strong bonding to the substrate. OLC (10 vol%)-TiN0.3 (10 vol%)-Si3N4 composites were prepared at 5 GPa, 1500 °C and held for 15 min. The Vickers hardness and fracture toughness were determined to be 18.6 GPa and 6.6 MPa m1/2, flexural strength of 531 MPa, and showed higher high-temperature hardness. This was higher than the typical values reported for Si3N4 ceramics (15–17 GPa). This work provides a new strategy for low-temperature of Si3N4 composites with both high hardness and high toughness.

Enhancing tribo-mechanical, microstructural morphology, and corrosion performance of AZ91D-magnesium composites through the synergistic reinforcements of silicon nitride and waste glass powder

The present investigation has employed recycled waste glass powder (WGP) and silicon nitride (Si3N4) as reinforcing-agents within AZ91D-matrix composites. The composites were fabricated by employing the vacuum stir casting technique to mitigate the effects of oxidation and to ensure homogeneity, uniformity, and superior wettability among the AZ91D-matrix and reinforcements. A microscopic study provided confirmation of a uniform dispersion of WGP and Si3N4 particles throughout the AZ91D-matrix. The tensile strength of the AZ91D/WGP/Si3N4 composites rise with the inclusion of WGP particulates by up to 1.5 percent in AZ91D/7.5% Si3N4. However, the tensile strength of the AZ91D/9%Si3N4 composite have showed maximum value as compared to other chosen formulations/combinations in the current investigation. The tensile strength of AZ91D/1.5% WGP/7.5% Si3N4 composites has strengthened up to 12.13 percent with the comparison of base alloy AZ91D-matrix. In A1 formulated composite, the amount of WGP particulate has enhanced the hardness of the AZ91D-alloy by up to 1.5 percent. Findings, nevertheless has exhibited that the A6 formulated composite had superior outcomes in terms of hardness. The incorporation of “reinforcing-constituent particulates” with 1.5%WGP + 7.5%Si3N4 combination within the AZ91D-matrix, has further increased fatigue-strength by around 57.84 percent. A weight-loss of 0.312 mg was being unveiled for the A1 formulated fabricated composite. The weight-loss for the A6 formulated fabricated composite, however, was reported to be 0.294 mg. At 5 N loads, 2 m/s sliding speed, and 1000 m of sliding distance, the developed 1.5%WGP/7.5%Si3N4/AZ91D composites was reported to have a rate of wear, and frictional coefficient of 0.0025 mm3/m and 0.315, respectively. The investigation employing scanning electron microscopy (SEM) identified the presence of corrosion pits on the surfaces that had undergone corrosion. These pits were found to be a result of localised surface assaults occurring in corrosive environments. Additionally, SEM pictures of the worn surfaces indicated the emergence of microcracks, which may be associated to the conditions of cyclic loading. Moreover, the tensile-fractography examination for the developed 1.5%WGP/7.5%Si3N4/AZ91D composites has exhibited the brittle fracture failure, including cracks and debonding phenomena. In addition, the EDS spectra-analysis have revealed an apparent existence of the observed Mg-peak, Si-peak, Al-peak, Ca-peak, and O-peak for the 1.5%WGP/7.5%Si3N4/AZ91D composites. Furthermore, the utilisation of X-ray diffraction analysis effectively determined the existence of hard phases inside the AZ91D-matrix, which significantly contributed to the reported enhancement in wear resistance. The development of harder-phases has included, α-Mg, Al12Mg17, SiO2, Si3N4, MgO, and CaO phases within the composite has been accountable for the enhancement of the tribomechanical, and wear-resistance characteristics of the AZ91D/WGP/Si3N4 composites. The Si3N4 has been discovered to have a substantial impact on enhancing mechanical performance and raising the resistance to wear.

Assessment of mechanical and tribological behavior of Mg-4Zn-1RE-0.7Zr alloy: Novel mixture of Si3N4/TiC/MoS2 utilizing casting technique

In the modern era, manufacturers aim for their parts to possess a sleek finish and increased durability to ensure continued functionality. Both the automotive and aerospace industries are actively seeking new materials and methodologies to enhance the surface quality of components during the preparation process and make the most of available resources. Employing casting, advanced techniques, and new materials is crucial for achieving this goal. Industries commonly utilize alloys and composite materials in the production of their components. This study focuses on magnesium composite Mg-4Zn-1RE-0.7Zr alloy to find the influence of varying three different reinforcement particles on mechanical properties and wear rate. An attempt was made to choose a constant 5% Si3N4 as the primary reinforcement and 2.5% to 7.5% of TiC/MoS2 as the secondary reinforcement, respectively. The samples of magnesium hybrid composites are prepared using a centrifugal casting process. The ZE 41 alloy/5% (TiC-MoS2)/5%Si3N4 has a high tensile strength of 942 MPa. In addition, 5% TiC/5% MoS2 with 5% Si3N4 composite has enhanced hardness, which is beneficial for transmission in aircraft like Boeing 727 and die-casting fittings in automobile applications.

Exploring the morphologies and corrosion performances of AZ31 alloy composites reinforced with silicon nitride

In this study, the effects of silicon nitride (Si3N4) particles on the microstructure and corrosion characteristics of AZ31 matrix composites in a 3.5% NaCl solution are examined with the help of an electrochemical test. Varying wt.% of Si3N4 particles (2, 4, 6, 8, 10, and 12 %) is used to fabricate matrix composites via a vacuum-assisted stir-casting approach. The developed composites and base alloys are characterized by energy dispersive X-ray analysis (EDAX) and scanning electron microscopy (SEM). Microscopic images demonstrate that the addition of reinforcement enhances the microstructural interfacial integrity between the Si3N4 and AZ31 matrix. EDAX results confirm the presence of Si3N4 particles in composites. The findings of electrochemical studies confirmed that AZ31's corrosion resistance substantially improved as its Si3N4 content increased. AZ31-10%Si3N4 exhibits a more tremendous corrosion potential (Ecorr) and a two-order-of-magnitude lower corrosion current density (icorr). Compared to the other samples, AZ31-10%Si3N4 exhibits superior polarization resistance. Compared to AZ31-2%Si3N4, AZ31-10%Si3N4 exhibits a 3.5-fold increase in polarization resistance. The results show that the AZ31 alloy with 10% Si3N4 exhibits superior corrosion resistance, followed by the AZ31-12%Si3N4, AZ31-8%Si3N4, AZ31-6%Si3N4, AZ31-4%Si3N4, and AZ31-2%Si3N4. The collective outcomes of the investigation indicate that the AZ31-10%Si3N4 composite may have the potential to enhance the corrosion behavior of AZ31 alloys.

A TEM study of nanostructures and interfaces in the hot-press sintered ZrB2–SiC–Si3N4 composites

A fully dense ZrB2–30 vol% SiC composite containing 5 wt% Si3N4 and 4 wt% phenolic resin (1.6 wt% carbon) was sintered using the hot-pressing route under the external pressure of 10 MPa at 1900 ºC for 2 h. The microstructural evolution and interfacial phenomena were scrutinized using advanced microscopy facilities such as high-resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM). The FESEM images showed the ZrB2 and SiC grains without any evidence of Si3N4. The formation of the hexagonal BN (hBN) phase was proven in the sintered composite. The hBN nanosheets had a graphite-like morphology with an average thickness of 20 nm. This phase has a perpendicular orientation to the pressure direction and prevents abnormal ZrB2 grain growth. Two types of ZrB2/SiC interfaces were detected, which exhibited an amorphous phase along with the grain boundary and a clean/smooth interface, resulting from the Si3N4 addition. HRTEM and inverse fast Fourier transform (IFFT) observations disclosed that the d-spacing value in the ZrB2 grain (0.335 nm) is higher than those reported in the literature. Furthermore, it was found that the exerted pressure during the sintering distorted atomic planes. The presence of numerous dislocations within the ZrB2 grains confirmed dislocation creep as the main densification mechanism.

Preparation and Water Lubrication Behaviors of Al-Cu Alloy-Based Si3N4 Composites

Preparation and Water Lubrication Behaviors of Al-Cu Alloy-Based Si3N4 Composites

Influence of N-doped aluminosilicate as an electrolyte on the properties of all-solid-state electrochromic devices

As an optical property with excellent dielectric properties combined with antireflection, AlSiON is not currently being investigated as electrochromic devices. Based on the optimized Al3+ solid-state electrolyte Al2SiO5, which is doped with different levels of N elements, the opto-electrical properties of the formed AlSiON in electrochromic devices have been systematically examined. AlSiON with an N-doping ratio of 3.4% achieves outstanding optical modulation (58.17%) and switching speed (22.2 s for coloring and 3.5 s for bleaching), as well as an effective reduction of leakage currents (68.39 μA/cm2) in electrochromic devices. By XPS analysis, the N content of 3.4% AlSiON is internally bonded with a proportion of Si–N to Al–N bonds, which generates a dielectric high Si3N4 composition effectively blocking electron breakdown.

Tribo-mechanical, physical and thermal behaviour of Al/Si3N4 composite with and without the addition of Cu, Ni and Cr entropy elements

In the present investigation, a comparative study has been presented between Al/Si3N4 and entropy elements (Cu, Ni and Cr) mixed Al/Si3N4 composite material. The investigation revealed that the tensile strength and hardness of base material were enhanced by 23.65% and 56.66% respectively with an increase of 10 wt. % of Si3N4. The tensile strength of Al and Al/10 wt. % Si3N4 composite was enhanced by 46% and 18% respectively after the addition of entropy elements 1.5 wt. % Cu, 1.5 wt. % Ni and 1 wt. % Cr. Further, the same wt.% of entropy elements enhanced the hardness of Al and Al/10 wt. % Si3N4 composite by 83.66% and 27%, respectively. The ductility and toughness of the composite were further improved by adding the 1.5 wt. % Cu, 1.5 wt.% Ni and 1 wt.% Cr in Al/10 wt. % Si3N4 composite. However, corrosion weight loss, volume thermal expansion and wear of the composite are reduced by adding the entropy elements. The number of grains per square inch for Al/10 wt% Si3N4 composite with and without adding the 1.5 wt. % Cu, 1.5 wt.% Ni and 1 wt.% Cr was found to be 3590.57 and 2385.37, respectively. The addition of entropy elements results in a finer grain structure of the composite which shows grain refinement.

Comparative Study on Mechanical Property and Fracture Behavior of Age-Hardened LM4 Monolithic Composites Reinforced with TiB2 and Si3N4.

The study aimed to compare and analyze the mechanical property and fracture behavior of LM4 composites reinforced with TiB2 (1-3 wt.%) and Si3N4 (1-3 wt.%) ceramic powders. A two-stage stir casting process was employed for the effective preparation of monolithic composites. To further enhance the mechanical properties of composites, a precipitation hardening treatment (both single (SSHT) and multistage (MSHT), followed by artificial aging at 100 and 200 °C) was conducted. From mechanical property tests, it was understood that in both the monolithic composites, the properties improved with an increase in wt.% of reinforcements, and composite samples subjected to MSHT + 100 °C aging treatment bested other treatments in terms of hardness and UTS values. Compared to as-cast LM4, there was a 32 and 150% increase in hardness and a 42 and 68% increase in UTS for as-cast and peak-aged (MSHT + 100 °C aging) LM4 + 3 wt.% TiB2 composites, respectively. Similarly, there was a 28 and 124% increase in hardness and a 34 and 54% increase in UTS for as-cast and peak-aged (MSHT + 100 °C aging) LM4 + 3 wt.% Si3N4 composites, respectively. Fracture analysis of the peak-aged composite samples confirmed the mixed mode of fracture in which brittle mode was dominating.

Effect of microwave sintering on the microstructure and mechanical properties of Al-Al2O3-Si3N4 hybrid composite fabricated by powder metallurgy techniques

In the present investigation, Si3N4 has been used in the partial replacement of SiC with Al/Al2O3 composite for the application in the automobile industries parts. A microwave sintering technique was employed for the processing of the composite. The aluminum-based composite was developed with the constant 5 wt.% of Al2O3. The weight percent of Si3N4 increased from 2.5% to 7.5%. Uniform distribution of the reinforcement particles was observed for the composition Al-5 wt.% Al2O3 − 2.5 wt.% Si3N4 composite and Al-5 wt.% Al2O3 − 5 wt.% Si3N4 composite. Optical microscope images Al-5 wt.% Al2O3 − 5 wt.% Si3N4 composite showed that the dispersion of the reinforcement (Al2O3 and Si3N4) has been done in a very fine and dense manner. Dispersion of reinforcement in a very dense manner helped in enhancing the mechanical properties of the composite. EDX pattern of Al-5 wt.% Al2O3 − 5 wt.% Si3N4 composite showed the maximum weight percentage of an element of Al, followed by Si, O, and N. Minimum porosity was found to be 0.045% for the composition Al-5 wt.% Al2O3 − 2.5 wt.% Si3N4. However, the percent porosity of the Al-5 wt.% Al2O3 − 5 wt.% Si3N4 was 0.072%. The hardness, compressive strength, and tensile strength of aluminum were improved by about 82.85%, 18.94%, and 62.60% respectively with respect to aluminum after adding 5 wt.% Al2O3 and 5 wt.% Si3N4. XRD of the Al/Al2O3/Si3N4 composite showed the presence of Al, Al2O3, Si3N4, MgAl2O4, and Al2Cu phases. Thermal expansion and corrosion behavior were also observed to identify the Al2O3 and Si3N4 addition effect in the aluminum alloy.