Properties Of Ceramics Research Articles

Comparative study of the structural parameters of reaction-sintered ceramics based on silicon carbide using digital materials science methods

Reaction-sintered ceramic materials were synthesized: silicon carbide and diamond-silicon carbide composite. The microstructure was studied and the physical and mechanical properties of composite ceramics were determined. It has been experimentally shown that the numerical parameters of the structure ― lacunarity and Voronoi entropy, obtained using digital materials science methods, allow a comparative assessment of the homogeneity of the ceramic structure and substantiation of its strength advantages.

Influence of the mechanical activation process on the corrosion of Ti2⁠AlN MAX phase obtained by hot pressing

The Ti2AlN MAX phase is known for its unique blend of metallic and ceramic properties, including high electrical and thermal conductivity and excellent oxidation and corrosion resistance. This study focuses on the influence of the mechanical activation process on the electrochemical properties of Ti2AlN in a saline environment. High-purity powders of AlN and Ti were mechanically activated or mixed and sintered to synthesize the Ti2AlN MAX phase. The electrochemical behavior was assessed through potentiodynamic curves and electrochemical impedance spectroscopy, while surface characteristics were analyzed using SEM-EDS and XPS post-exposure to a 3.5% NaCl solution. Results reveal that Ti2AlN forms protective Al2O3 and TiO2 layers, enhancing its corrosion resistance. Mechanically activated samples (MAP) displayed different corrosion behavior than non-activated samples (NMAP), with MAP showing reduced corrosion resistance. This discrepancy is attributed to differences in oxide formation and microstructural changes due to mechanical activation. This research not only elucidates the corrosion mechanisms of MAX phases in chloride-rich environments but also analyzes the effect of mechanical processing on their properties, contributing to developing Ti2AlN applications where high durability and resistance are critical.

A comparative study of LiTa2PO8 ceramics prepared with different lithium sources

In advancing lithium-ion batteries, solid electrolytes like LiTa2PO8, a Li-ion conductor with high bulk conductivity (~10−3 S/cm), show promise for all-solid-state battery technology. Here, we investigate the impact of different Li sources and their excess on the structural, microstructural and electrical properties of LiTa2PO8 ceramics. Employing diverse characterization techniques, including XRD, MAS NMR, TMA, SEM/EDS, IS, DC potentiostatic polarization, and density measurements, we unveil significant impact of the source of lithium ions and its excess on electrical properties. The sample without excess LiNO3 source exhibited the highest σtot = 5.2×10−4 S/cm at 30°C. Notably, the grain conductivity remained constant at ca. 3 mS/cm, irrespective of the chosen lithium source and excess. The microstructural analysis uncovered correlations between variations in total ionic conductivity and changes in the nature and concentration of secondary phases. Additionally, it revealed the influence of the arrangement of grains affecting the grain boundaries and porosity regions.

Fabrication and toughening mechanisms of B4C-SiCf ceramics based on TiB2 interface regulation

The interphase is vital for optimizing the mechanical properties of fiber-reinforced B4C ceramics. In this study, the TiB2 interface composed of one or several layers of fine TiB2 grains was in-situ formed between B4C and SiC fibers by introducing Ti3SiC2-coated SiCf into B4C matrix. The TiB2 interface not only obviously reduced the densification temperature of the B4C ceramics, but also enhanced the mechanical properties. The micro-mechanics modeling was performed to investigate the weak interphase and thermal residual stress distribution induced by TiB2, where the stress tend to deflect or propagate at the fiber-matrix interface, compared to B₄C-SiCf ceramics. The particle toughening inside the TiB2 interface layer and stress transfer at the weak interface were identified as the major factors for the improvement of fracture toughness in this system. These results provide valuable guidance for improving the comprehensive performance of B4C-SiCf ceramic composites by interface regulation in future investigations.

Thermophysical Properties of (Y1-xErx)TaO4 Ceramics

A series of (Y1-xErx)TaO4 ceramics (x=0/6, 1/6, 2/6, 3/6, 4/6, 5/6, 6/6) were prepared using powders synthesized by the reverse co-precipitation technique. Investigations were conducted into the phase compositions, microstructure, and thermophysical characteristics. In contrast to yttria-stabilized zirconia (YSZ) ceramics, (Y1-xErx)TaO4 ceramics demonstrate reduced thermal conductivity and Young's modulus, along with greater coefficient of thermal expansions (CTEs). The impact of Er and Y elements on separation interferes with the parabolic relationship between thermal conduction and the composition of (Y1-xErx)TaO4 ceramics, modifying their thermal diffusion and conductivity patterns. Furthermore, the performance of (Y1-xErx)TaO4 ceramics was optimized by adjusting the ratio of Er/Y, from which (Y1-xErx)TaO4 ceramics exhibited lower thermal conductivity (1.38∼1.72 W·m-1·K-1 @ 800 °C), higher CTEs (9.24×10-6∼10.9×10-6 K-1 @ 1000 °C) and more excellent mechanical properties comparable to YSZ. Herein, (Y1-xErx)TaO4 ceramics show great potential for thermal barrier coating applications.

High-strength and Low-Thermal-Conductivity Porous Multi-Principal Cation Mullite Ceramic

The secret of porous mullite as a thermal insulation material lies in its excellent mechanical properties and lower thermal conductivity. The optimization of performance often depends on the structure design. Herein, via NH4HCO3 as a sacrificial material to fabricate porous multi-principal cation mullite (MPCM) ceramics that have not been reported for 4 doping elements (Mg, Ti, Zr, and Cr) by a sacrificial template method. The novelties of the present work are: (1) The multiple components cause a serious lattice distortion at the microscopic scale, which increases the mechanical properties of porous MPCM ceramics. (2) Porous MPCM (total porosity ≈ 54%) exhibits superior compressive strength (≈ 93 MPa), and the compressive strength with porosity was well modeled based on the Balshin and Rice equations. (3) As a proof-of-concept, we predict the thermal conductivity of pure mullite (PM) with the same porosity as MPCM ceramics. Here it proved the superiority of MPCM (0.67 W∙m-1∙K-1, 1,000 °C) as a thermal insulation material over conventional PM. Porous MPCM prepared by NH4HCO3 will pave a new path for the design of advanced thermal-insulation materials.

Superb thermal stability achieved in Na0.25K0.25Bi2.5Nb2O9-based piezoelectric ceramics via Bi deficiency

Na0.25K0.25Bi2.5Nb2O9-based ceramics woule become one of the excellent candidate materials suitable for high-temperature applications, given that their piezoelectric properties can be effectively improved. In this work, a strategy of reducing the Bi content was used to improve the piezoelectric properties and thermal stability of Na0.25K0.25Bi2.5Nb2O9-based ceramics by means of designing the compositions of the Na0.25K0.25Bi2.5+xNb2O9+3x/2 (-100xBi-NKBN, x = 0, -0.01, -0.03, -0.05, -0.07, -0.10). The effect of the Bi deficiency on the crystal structure, microscopic morphology, and electrical properties of NKBN-based ceramics was systematically investigated. By comparison, the Na0.25K0.25Bi2.45Nb2O8.925 ceramic obtains a large d33 of 20 pC/N, a high Tc of 651 ℃, and a high resistivity ρdc of 3.3 × 105 Ω cm at 600 ℃. The results demonstrate that the good d33 mainly stems from the increased lattice distortion and reduced oxygen vacancy concentration. More importantly, the d33 value can maintain 97% of its initial value after it was annealed at 600 ℃, showing excellent thermal stability. This work provides a new idea for solving the problem of poor piezoelectricity of NKBN-based ceramics and lays the foundation for applying NKBN-based ceramics in the high-temperature field.

Impact of strontium doping on the structural and NTCR properties of ZnO ceramics

Impact of strontium doping on the structural and NTCR properties of ZnO ceramics

Approximating Nucleation Rates of Glass Ceramics Using In-Situ X-ray Diffraction

Glass ceramics are ideal for applications ranging from the culinary to defense industries. The properties of glass ceramics are a strong function of their microstructure, which in turn is controlled by constitutive nucleation and growth treatments. Nucleation has been extensively studied but remains an experimental and theoretical challenge. Traditional isothermal methods for measuring nucleation rates require time-consuming measurements and careful statistics, leading to only a few material systems with nucleation data available, approximately one-hundred glass systems were studied in half a century. To overcome these challenges, we present a new non-isothermal technique utilizing in-situ X-Ray Diffraction (XRD) with data analyzed through a modified Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. Three homogenous nucleated glass systems were analyzed: Li2O•2SiO2 (lithium disilicate), Na2O•2CaO•3SiO2 (combeite), and Li2Oׅ•2B2O3 (lithium diborate). This method utilizes crystallized fractions through XRD, allowing resolution far beyond microscopy techniques. It was thus possible to compare the evolution of the crystallized volume fractions by X-ray diffraction with optical microscopy from literature. This method was successful in reproducing the experimental nucleation curve from the temporal development of the number density and crystal size within four orders of magnitude, while also achieving the correct peak position, leading to a new method to rapidly approximate the nucleation rate of complex glass-ceramics.

Effects of structural defects on dielectric properties of Nb-doped SrTiO3-based ceramics

In this study, the Nb-doped SrTiO3 (SNT) ceramics were prepared using the traditional solid-state reaction method. It was observed that the room temperature permittivity exhibited a significant increase from 102 to 104 as the partial pressure of oxygen in the sintering atmosphere gradually decreased. To elucidate the mechanism driving these observed changes in permittivity, the microstructure and dielectric properties of SNT ceramics were investigated. The results indicated that the presence of Ti3+/Ti4+ polar structure and the defect dipole [Ti4+∙e−Vo∙∙−Ti4+∙e] resulted in the increase of permittivity, but only [Ti4+∙e−Vo∙∙−Ti4+∙e] can reduced dielectric loss. The formation and concentration of these defects would be influenced by the oxygen partial pressure in the sintering atmosphere, consequently influencing the alteration in the permittivity.

Optimizing the mechanical properties of Al4SiC4 ceramics: A study on incorporating Y2O3 and spark plasma sintering

The present study focuses on optimizing the mechanical properties of Al4SiC4 ceramics by incorporating Y2O3 additives and utilizing spark plasma sintering. A native oxide layer, predominantly composed of Al2O3 with trace amounts of SiO2, was detected on the surface of the Al4SiC4 powder. Following sintering at 1823 K, Al4SiC4 was identified as the dominant phase, with Y3Al5O12 (YAG) recognized as the secondary phase. The effects of YAG on grain growth in Al4SiC4 is clarified based on experimental findings and molecular dynamics simulations. Additionally, the presence of SiO2 within the native oxide layer of Al4SiC4 is examined from both microstructural and thermodynamic perspectives. Precise optimization of the Y2O3 content is essential for enhancing mechanical properties, with an optimal content of 3 wt% yielding maximum values of flexural strength and fracture toughness at 436 MPa and 4.0 MPa·m1/2, respectively, along with Vickers hardness values of 12.0 GPa.

Study of the High-Temperature Sintering Characteristics of Boron Oxide Composite Silicon-Based Ceramics

This paper explores the application of boron oxide (B2O3) as a sintering additive in silicon-based (SiO2) ceramics, focusing on its impact on the sintering process and resulting ceramic properties. Composite silicon-based ceramic shells with boron oxide content ranging from 0 to 4 Wt% were prepared using digital light processing (DLP) technology. This study examines the effects of boron oxide on sintering temperature, apparent porosity, shrinkage rates, and mechanical properties during high-temperature sintering. Experimental results indicate that, as boron oxide content increases, the shrinkage rate of the ceramic samples rises progressively, with shrinkage in the XY direction increasing from 4.57% to 16.40% and in the Z direction from 6.25% to 17.03%. Concurrently, the apparent porosity decreases with higher boron oxide content, ranging from a maximum of 36.17% to a minimum of 23.27%. Bulk density also improves from 1.49 g/cm3 to 1.78 g/cm3. The bending strength trend first rises and then declines, peaking at 15.39 MPa at a boron oxide content of 3 Wt%. X-ray Diffraction and Energy Dispersive Spectroscopy analyses confirm that the addition of boron oxide promotes the formation of beta-quartz and that its liquid-phase behavior at high temperatures aids in enhancing ceramic densification. This study demonstrates that an appropriate amount of boron oxide can effectively lower the sintering temperature of silicon-based ceramics while improving their mechanical properties, providing a theoretical foundation and practical basis for broader industrial applications.

Effect of cigarette smoking on the optical properties of contemporary dental ceramics: an in-vitro analysis.

Cigarette smoking is the most common form of tobacco use worldwide. With the frequent introduction of new dental materials, the effect of smoking on their optical properties such as long term color stability, should to be thoroughly investigated. This in-vitro study aims to investigate the effect of smoking on the optical properties of contemporary dental ceramics used currently for restoration of teeth. Five different materials in two shades (B1 and C1) were used with 15 samples from each pressable lithium disilicate (Emax), layered lithium disilicate (Lmax), porcelain fused to metal (PFM), monolithic zirconia (MZr) and layered zirconia (LZr) were used (n=75). The samples were exposed to conventional cigarette smoke and color stability was assessed at four different time intervals i.e., baseline, 1 week, 1 month and 6 months. CIELAB color space (CIE L*a*b*) values were used to evaluate the color difference (ΔE). A one-way analysis of variance (Anova) was used for statistical analysis of ΔE. Significant P-value was kept as <0.05, followed by Tukey post-hoc test. All test materials demonstrated significant color differences (ΔE) after exposure to cigarette smoke (p<0.05). For shade B1, the highest change in shade ΔE 17.02 was exhibited by Lmax, whereas the least change in shade was exhibited by Emax followed by PFM at values of ΔE 10.11 and 11.2 respectively. For shade C1, the highest change (11.47) in shade at 6 months was demonstrated by MZr, whereas lowest values of ΔE were exhibited by Emax (7.52). Traditional smoking causes significant change in shade of dental ceramics which can affect the esthetics of the patients. All material samples tested showed the values of ΔE > 3.3 which is higher than the acceptable range. Lowest color change was observed in Emax and PFM.

Impact of Sintering Aid Type and Content on the Mechanical Properties of Digital Light Processing 3D-Printed Si3N4 Ceramics

Impact of Sintering Aid Type and Content on the Mechanical Properties of Digital Light Processing 3D-Printed Si3N4 Ceramics

Microstructure, Mechanical, and Tribological Properties of SiC-AlN-TiB2 Multiphase Ceramics

SiC multiphase ceramics were prepared via spark plasma sintering using AlN and TiB2 as the second phase and Y2O3 as a sintering additive. The effects of TiB2 content (10 vol.% and 20 vol.%) and sintering temperature (1900 °C to 2100 °C) on the phase composition, microstructure, and mechanical and tribological properties of SiC multiphase ceramics were investigated. The results showed that Y2O3 reacts with Al2O3 on the surface of AlN to form the intercrystalline phase Y4Al2O9 (YAM), which promotes the densification of the multiphase ceramics. The highest density of SiC multiphase ceramics was achieved at 10 vol.% TiB2 content. Moreover, TiB2 and SiC exhibited good interfacial compatibility. In turn, a thin solid-solution layer (~50 nm) was formed by SiC and AlN at the interface. The periodic structure of SiC prevented the dislocation movement and inhibited the base plane slip. The most optimal mechanic characteristics (a density of 98.3%, hardness of 28 GPa, fracture toughness of 5.7 MPa·m1/2, and bending strength of 553 MPa) were attained at the TiB2 content of 10 vol.%. The specific wear rates of SiC multiphase ceramics were (4–8) × 10−5 mm3/N·m at 25 °C and 2.5 × 10−5 mm3/N·m at 600 °C. The wear mechanism changed from abrasion at 25 °C to a tribo-chemical reaction at 600 °C. Therefore, adding lubricious oxides of TiB2 is beneficial for the improvement in wear resistance of SiC ceramics at 600 °C.

Effect of sub‐coercive degradation on the local piezoelectric properties in lead zirconate titanate ceramics

AbstractLead zirconate titanate (PZT) is a widely recognized piezoelectric ceramic exhibiting excellent dielectric and ferroelectric properties over a wide range of temperature and frequency, making it desirable for applications such as capacitors, piezoelectric transducers, and actuators. Being subjected to repeated electrical loading in various applications, a progressive decrease in the functionality can happen, leading to device failure over time. Therefore, understanding degradation phenomena in all aspects is of importance to expand the lifespan of electronic devices. Despite of many studies focusing on the macroscopic properties of ferroelectrics related to degradation, such as switchable polarization, little is known about the change on local ferroelectric and piezoelectric properties and the domain structure induced by degradation. This paper reports the effect of sub‐coercive electrical cycling on local static and dynamic piezoelectric properties for PZT ceramic using piezoresponse force microscopy (PFM). The piezoelectric properties are probed along the three sample directions (x, y, z) to gain comprehensive insights into the local domain orientation throughout the bulk PZT sample which is then compared with microscopically measured piezoelectric coefficients. The PFM results are analyzed with respect to changes in domain orientation (depolarization) as well as to reduction on piezoelectric material response (degradation) to identify the origin of the degradation behavior. Our results directly show a strong depolarization effect in the direction of the applied electric field because of sub‐coercive cycling although it leads to small or even no degradation in directions perpendicular to the applied electric field. However, the latter is associated with a notable change in dynamic polarization switching properties which are strongly tied to the local domain structure. Our study shows that the origin of the degradation can be identified by analyzing the statistical change of local piezoelectric properties.

Exploring the effect of Ba2+ ions doping on the dielectric properties of SrSnO3 ceramics

Exploring the effect of Ba2+ ions doping on the dielectric properties of SrSnO3 ceramics

Achieving ultra-high resistivity and outstanding piezoelectric properties by co-substitution in CaBi2Nb2O9 ceramics

CaBi2Nb2O9 (CBNO) ceramics exhibit significant potential in the development of piezoelectric sensors suitable for extreme environments such as aerospace, metallurgy, and nuclear power plants. While previous studies have enhanced the piezoelectric response of CBNO ceramics, their insulating properties at high temperatures still require improvement. In this work, co-substitution of (Li0.5Bi0.5) at A site and Mn at B site was designed to improve the electrical properties of CBNO ceramics. Defect dipoles induced by the bound between Mn and oxygen vacancies restrict the movement of oxygen vacancies at high temperatures. Meanwhile, co-substitution of Ca by (Li0.5Bi0.5) reduces both the sintering temperature and volatilization of Bi2O3 during the sintering process. This modification results in an ultra-high TC of 928 °C and an exceptional resistivity of 2.85 MΩ cm at 600 °C for Ca0.96(Li0.5Bi0.5)0.04Bi2Nb1.98Mn0.02O9 ceramics. Furthermore, the ceramic exhibits excellent piezoelectric properties (d33 of 15.2 pC/N and kp of 6.9 %), ferroelectric properties (Pr of 9.42 μC/cm2), and thermal stability (degeneration of d33 only 6 % after annealing at 900 °C for 2 h). This work offers a practical strategy for simultaneously achieving both a high piezoelectric response and outstanding insulating properties in the CBNO system.

Investigation of Luminescent Properties of Optical Ceramics Based on YAG and Luag Co-Activated by Yb3+ and Er3+

Investigation of Luminescent Properties of Optical Ceramics Based on YAG and Luag Co-Activated by Yb3+ and Er3+

N-induced antibacterial capability of ZrO2-SiO2 glass ceramics by ion implantation

Periodontal disease caused by bacterial accumulation is a critical issue affecting the longevity of related materials and implants. Enhancing the antibacterial properties of glass ceramics remains a significant challenge. Due to their excellent mechanical properties, ZrO2-SiO2 glass ceramics have shown great potential in dental restoration. Here, to endow ZrO2-SiO2 glass ceramics with antibacterial properties, nitrogen ion implantation was performed to modify their surfaces. The effects of nitrogen fluence on the microstructural, mechanical and antibacterial properties were investigated. The results showed that phase transformation from tetragonal to monoclinic phase occurred after ion implantation. Surface hardening was observed in the sample under the low fluence ion implantation. Partial amorphization and blistering were observed at the highest fluence of 6.0 × 1017 ions/cm2. XPS analysis revealed that the implanted nitrogen ions mainly form O-Zr-N, N-Si-O and Si-N bonds. Staphylococcus aureus testing showed that the antibacterial properties of ZrO2-SiO2 glass ceramics can be enhanced after implantation, which may be attributed to the formation of reactive nitrogen species. The results show that nitrogen implantation can enhance the antibacterial properties of ZrO2-SiO2 glass ceramics without compromising their mechanical properties.