High-temperature Ceramics Research Articles

CuO-based materials for thermochemical redox cycles: the influence of the formation of a CuO percolation network on oxygen release and oxidation kinetics

Thermochemical redox cycles such as chemical looping combustion (CLC) are an economically promising CO2 capture technology that rely on the combustion of a hydrocarbon fuel with lattice oxygen that is derived from a solid oxygen carrier. The oxygen carrier is typically regenerated with air. To increase the agglomeration resistance and redox stability of the oxygen carriers, the active phase is often stabilized with high Tammann temperature ceramics, resulting in the formation of so-called cermet structures. It has been hypothesized that the redox performance of the cermets depends critically on the conduction pathways for solid-state ionic diffusion and the activation energy for charge transport. Here, we investigate the influence of the formation of a percolation network on the electrical conductivity and the rate of oxidation for CeO2-stabilized Cu. We found that for oxygen carriers that contained 60 wt. % CuO, the charge transport occurred predominately via Cu/CuO conduction pathways. Below the percolation threshold of CuO, the conduction of charge carriers took place via CeO2 grains, which formed a continuous network. The measurements of charge transport and redox characteristics confirmed that the activation energy for charge transport through the cermet increased with decreasing Cu content. This indicates that the solid-state diffusion of charge carriers plays an important role during re-oxidation.

Realization of high piezoelectric performance in bismuth titanate niobate via B-site mixed-valance doping

Aurivillius-compound Bi3TiNbO9 (BTN) based high-temperature piezoelectric ceramics doped with mixed-valence cations (Mo1/3Cr2/3)4+ at the lattice B-sites, Bi3Ti1−x(Mo1/3Cr2/3)xNbO9 (BTN-MC100x, x = 0 −0.07), were prepared via the solid-state reaction method. The incorporation of the (Mo1/3Cr2/3)4+ ions into the BTN lattice promotes the preferential growth of grains along the a-axis, making it easier for polarization vector to flip. The optimized composition BTN-MC5 ceramic had a large d33 of 20.3 pC/N with a high TC of 901 °C. It was found that the donor doping effect of (Mo1/3Cr2/3)4+ and the formation of (CrTi′–VO⋅⋅–CrTi′)×defect dipoles contribute to reduce the concentration of oxygen vacancies, thus increasing the resistivity (2.2 ×105 Ω cm at 600 °C). In addition, the d33 of the BTN-MC5 ceramic exhibits an excellent thermal stability against depoling temperature Td. These findings indicate that the BTN-MC5 ceramic is promising candidate for the preparation of high-temperature piezoelectric sensors.

Welcome to International Journal of Materials, Manufacturing and Sustainable Technologies: A Journal Focussing on the advanced Materials, Manufacturing Processes and Sustainable Technologies

Materials are important in the development of human civilization. In present era materials are of the utmost importance for researcher, scientist and engineers because usage of the right materials is very important when designing different systems. In human history they have used stone, clay, skin and wood for making weapons, instruments and shelter etc. Need for better quality weapons brought Bronze Age followed by Iron Age. In continuation Iron and steel have advantage of stronger materials for different applications [1]. Iron was available in abundant and this commonness of the material affected human kind in every aspect. We are presently in space age marked by many stronger and light materials like high strength iron and steel materials [2], composites, electronic materials like semiconductors, smart materials for space voyage like high temperature ceramics, biomaterials, high strength coating materials etc. [3]. In conclusion, materials constitute foundation of modern technology era.

Synthesis of High-Temperature Ceramics Based on Hafnium Carbide Using an Oxidative Constructing Approach

Synthesis of High-Temperature Ceramics Based on Hafnium Carbide Using an Oxidative Constructing Approach

Low-temperature preparation and electrical properties of CaBi2Nb2O9 piezoelectric ceramic by addition of B2O3

CaBi2Nb2O9 ceramics were fabricated via the solid-state reaction method by the addition of B2O3 as a sintering aid at lower sintering temperatures than that prepared without B2O3. Ferroelectricity, piezoelectricity, and resistivity can be still greatly enhanced when the sintering temperature is decreased from 1075 °C for CaBi2Nb2O9 to 975 °C for CaBi2Nb2O9–0.25 wt. % B2O3. The high resistivity and weak c-axis texture ensure that the ceramics can be fully polarized in a high enough electric field. The increased spontaneous ferroelectric and remanent polarization result in a significant enhancement in the piezoelectric properties of CaBi2Nb2O9–0.25 wt. % B2O3. The sample sintered at 975 °C possesses a high piezoelectric coefficient d33 of ∼15.0 pC/N and resistivity of 1.4 × 106 Ω cm (at 600 °C) along with a high ferroelectric Curie temperature TC of ∼954 °C. This work is beneficial for the preparation of high-temperature piezoelectric ceramics with excellent electrical properties at a low sintering temperature.

Future insights on high temperature ceramics and composites for extreme environments

AbstractThis document summarizes key research directions as they emerged during the proceedings of the Inaugural Orton Workshop that aimed to define scientific areas of current interest to the ceramics community around the theme of: “High Temperature Ceramics and Composites for Extreme Environments.” The topic was selected due to the timely interest in such materials to meet the needs of hypersonic aviation and space exploration and habitation. Experts from funding agencies supporting ceramics research, thought‐leaders from academia with expertise spanning materials processing, characterization, and modeling, as well as research and development leaders from key (aviation‐related) industries, gathered to evaluate the state‐of‐the‐art in this field and to address key questions with the intent of accelerating research and development efforts on all fronts. Highlights of the work presented and of the discussion and brainstorming sessions are provided here. It was the purpose of the organizers (The Orton Ceramic Foundation and the Orton Chair in Ceramic Engineering at OSU) to establish this event as a service to the Ceramics community in the spirit the founder of the field of Ceramic Engineering, Dr. Edward Orton Jr.

Optimizing the stability and electrical transport properties of CeNbO4+δ-based oxide ceramics by regulating oxygen ion content

CeNbO4+δ ceramics have attracted extensive research interest because of their unique mixed ion-electron transport characteristics and interesting structure-functional characteristics caused by the difference in oxygen ion content. Although the change of oxygen ion content brings rich redox properties, it also causes serious crystal transformation and abnormal electrical transport properties. In order to obtain stable structure and excellent electrical transport properties, the directional regulation of the oxygen ion content has been realized through introducing Al2O3 and high temperature aging. After 600 h of aging at 1073 K, the prepared composite ceramics not only obtain a stable structure without crystal transformation, but also show good negative temperature coefficient (NTC) thermistor characteristics in the temperature range of 473 K–1273 K, in which the linear fitting maximum Pearson's r of the relationship between lnρ and 1000/T can reach 99.97%. The proposed method provides a new thought for the design and application of high-temperature electronic ceramics.

Electrical properties of Bi2.99(Li0.5Sm0.5)0.01Ti1-x(Mn1/3Ta2/3)xNbO9 high-temperature piezoelectric ceramics via oxygen vacancy defects tailoring

Tribismuth titanium niobium oxide (B3TiNbO9, BTNO) is one of the Aurivillius phases with the highest Curie temperature (Tc), but its piezoelectric coefficient (d33) is poor. When x = 0.045, high-temperature piezoelectric ceramics with d33 of 11.9 pC/N and Tc of 916.7 °C were prepared by (Mn1/3Ta2/3)(4+ω)+ modification of Ti4+ at B-site of Bi2.99(Li0.5Sm0.5)0.01Ti1-x(Mn1/3Ta2/3)xNbO9. The substitution will aggravate the distortion of BO6 octahedron due to the displacement of oxygen ions. The existence of Mn3+ in the dopant will act as an oxygen vacancy trap and then increase the resistivity. As a result, BTNO ceramics have enhanced piezoelectric properties as well as temperature and cycle stability. This work provides a theoretical basis for better high-temperature piezoelectric properties of A/B co-doped Aurivillius phase ceramics in the future.

Site-independent strong phonon-vacancy scattering in high-temperature ceramics ZrB2 and HfB2

Similar effects of metal and boron vacancies on phonon scattering and lattice thermal conductivity $({\ensuremath{\kappa}}_{l})$ of ${\mathrm{ZrB}}_{2}$ and ${\mathrm{HfB}}_{2}$ are reported. These defects challenge the conventional understanding that associates larger impacts to bigger defects. We find the underlying reason to be a strong local perturbation caused by boron vacancy that substantially changes the interatomic force constants. In contrast, a long ranged but weaker perturbation is seen in the case of metal vacancy. We show that these behaviors originate from a mixed metallic and covalent bonding nature in the metal diborides. The thermal transport calculations are performed in a complete ab initio framework based on Boltzmann transport equation and density functional theory. Phonon-vacancy scattering is calculated using ab initio Green's function approach. Effects of natural isotopes and grain boundaries on ${\ensuremath{\kappa}}_{l}$ are also systematically investigated, however we find an influential role of vacancies to explain large variations seen in the experiments. We further report a two-order of magnitude difference between the amorphous and pure-crystal limits. Our results outline significant material design aspects for these multifunctional high-temperature ceramics.

Design of Fe2B-based ductile high temperature ceramics: First-principles calculations and experimental validation

Iron Boride (Fe2B) has significant potential to be used as a wear- and corrosion-resistant ceramic because of its high hardness, good corrosion resistance, and low cost. However, the toughness and elastic heat resistance of Fe2B can be further improved under high-temperature wear conditions. First-principles energetics and phonon calculations showed that Ti, Cr, Mn, Co, Ni, Nb, Mo, Ta, and W can dissolve in Fe2B. Among these, Cr, Mn, and Ni can form a continuous solid solution in (Fe, M)2B. Furthermore, Ti, Cr, Mn, Co, Ni, Cu, Y, Nb, Mo, Ta, and W improved the toughness of Fe2B. The results were validated by the experimental results. It was found that the experimental fracture toughness of Fe2B doped with Cr and Ni reached 4.16 and 4.27 MPa m1/2, respectively, which are higher than 3.64 MPa m1/2 of pure Fe2B. Chemical bond analyses showed that the toughness was improved owing to the stiffening of the B–B bond and the invariability of the Fe–B bond in Fe2B by doping Cr and Ni with increasing pressure. The elastic heat resistance of alloyed Fe2B was related to the degree to which the B–B and Fe–B bonds weakened with temperature. The less these bonds strength weakened with increasing temperature, the better the elastic heat resistance. The bond strength of Fe–B and B–B bonds in Fe2B doped with Cr showed a minimum decrease with increasing temperature, whereas the bond strength of Fe–B and B–B bonds in Fe2B doped with Ta showed a maximum decrease with increasing temperature. This indicates that the alloying element Cr can improve the elastic heat resistance of Fe2B, while Ta decreases the elastic heat resistance of Fe2B.

First-principles investigation of structural stability, electronic and optical properties of suboxide (Zr3O)

Zirconium oxides (Zr-O) has been widely used in energy storage system, catalyst, microelectronic, optoelectronics, and high-temperature ceramics etc. Unfortunately, the ground state structure, electronic and optical properties of Zr3O are unclear until now. Here, we apply the first-principles calculations to study the structure, electronic and optical properties of Zr3O. Three Zr3O oxides: rhombohedral (R32), rhombohedral (R-3c) and hexagonal (P6322) phase are studied. The results show that three Zr3O oxides are thermodynamic and dynamical stabilities. The calculated phonon density of state (PhDOS) further demonstrates the stable of Zr3O oxides. In particular, it is found that the rhombohedral (R-3c) Zr3O is slightly more stable than the other two Zr3O oxides. Unlike ZrO2, the Zr3O oxides exhibit better electronic properties due to the electronic jump between Zr- excitation band and Zr- conduction band near the Fermi level. Compared to the hexagonal Zr3O, the host peak of the rhombohedral Zr3O move into the low energy region, which leads to the red shift phenomenon occurs. In addition, it is found that the rhombohedral (R32, No.155) Zr3O oxide has better storage optical properties compared to the other two Zr3O oxides.

Single-source-precursor synthesis and characterization of SiAlC(O) ceramics from a hyperbranched polyaluminocarbosilane

Abstract Polyaluminocarbosilane (PACS) as a single-source-precursor of SiAlC(O) ceramic was prepared by reacting a hyperbranched allylhydridopolycarbosilane (AHPCS) and aluminum(iii) acetylacetonate (Al(acac)3), and the PACS was characterized using gel-permeation chromatography, Fourier-transform infrared spectroscopy, and nuclear magnetic-resonance spectroscopy. The polymer-to-ceramic transformation of the obtained PACSs was investigated by Fourier-transform infrared spectroscopy and thermogravimetric analysis. The ceramic yield of the PACS was approximately 15% higher than that of the original AHPCS at 1,200°C. The phase composition and microstructure of the final ceramics were studied by X-ray diffraction, energy-dispersive spectroscopy, and scanning electron microscopy. The introduction of aluminum to the SiC(O) ceramics suppressed the β-SiC crystal growth and improved the density of the ceramics that were annealed at 1,800°C, which is advantageous for high-temperature ceramics. The aluminum content of the SiAlC(O) ceramics can be readily controlled by the Al(acac)3 content in the PACS precursors.

Phase development in metal-dropped silicon oxycarbides under water vapor and argon hybrid atmosphere

In this study, metal-modified silicon oxycarbides ceramics (SiOC/M, M = Fe, Al, and Zr) were fabricated, and the thermal stability of the SiOC/M (M = Fe, Al, and Zr) ceramics was investigated under the water-vapor- argon hybrid atmosphere. The phase and microstructural analysis showed that the thermal stability was in the order of SiOC/Zr ＞ SiOC/Al > SiOC/Fe. The SiOC/Zr and SiOC/Al ceramics possessed better thermal stability than SiOC/Fe ceramics, because they formed metallic oxides (ZrO2, mullite, or sillimanite). Additionally, the water-vapor-argon hybrid atmosphere increases the defects within the carbon clusters of SiOC/M ceramics and refines the lateral size of the nanocrystalline carbon. Understanding thermal stability and microstructural evolutions of metal-dropped polymer derived ceramics provided a new method for achieving high-temperature ceramics for application in an extreme environment.

First-principles investigation of equilibrium phase, mechanical and thermodynamic properties of the Nowotny TM5Si3C ternary phase

Although the TM-Si-C ternary compounds are potential high-temperature ceramics, the equilibrium phase, mechanical and thermodynamic properties of Nowotny phase (NP) are still unclear. Here, the structural stability, mechanical and thermodynamic properties of the TM5Si3C Nowotny phase (NP) are studied by the first-principles calcualtions. Four TM5Si3C ternary phases (TM = Mo, Nb, W and Ta) are considered. It is found that the equilibrium structure of the Nowotny phase (NP) is a TM5Si3C. In particular, the Mo5Si3C, Nb5Si3C, W5Si3C and Ta5Si3C are firstly predicted. Nb5Si3C has better thermodynamic stability in comparison to the other TM5Si3C. Furthermore, the calculated elastic properties show that four TM5Si3C not only exhibit similar strength in comparison to the corresponding TM5Si3 and TMSi2, but also show better ductility compared to the corresponding TM-Si binary silicides. The nature of mechanical properties of TM5Si3C is revealed by the electronic structure and difference charge density. In addition, it is further found that four TM5Si3C have high melting points and excellent thermodynamic stability. Naturally, the better thermodynamic properties of TM5Si3C is related to the vibration of C atom in a system.

Reactively sintered TiB2-based heteromodulus UHT ceramics with in-situ formed graphene for machinable concentrated solar light absorbers

The paper encompasses deeper understanding of sintering, properties and applications of nanostructured refractory ceramics with “hard”/”soft” ceramic phase combinations. TiB2–SiC–C Ultra High Temperature Ceramics in heteromodulus form with the in-situ formed nanostructured carbon were sintered via reactive route. It is shown that the green body compositions should account for zirconia contamination introduced during green body milling process. SEM and Raman spectroscopy showed that the in-situ segregating carbon forms platelets with structure of highly defected graphene multilayers and amorphous inclusions. Silicon carbide in the ceramics is present in 2H polytype form. The crack resistance of the ceramics is maximised at 8.4 MPa∙m1/2 for the material with 16 vol% of carbon. Ceramic drilling rate theory is developed and it is shown that the material removal for heteromodulus composite should account for soft phase shapes and distribution and hard phase removal in cascade pull-out events. The model explains significant machinability increase as the soft phase content rises above 20 vol%. The model also demonstrates how hard hetero-modulus material can be drilled with softer than the ceramic drills. Light absorption of the TiB2–SiC–C ceramics was analyzed and it is shown that the presence of high carbon content only reduces light absorption by approximately 10%. Final light absorption remains at above value for the most of concentrated solar energy absorbers. It is concluded that TiB2–SiC–C ceramic can be used as an effective concentrated solar light receiver.

Thermal response, oxidation and ablation of ultra–high temperature ceramics, C/SiC, C/C, graphite and graphite–ceramics

• Thermal responses, oxidation, and ablation of ultrahigh temperature ceramics, C/SiC, C/C, graphite, and graphite ceramics were systematically investigated. • These thermal protection materials exhibited remarkably different thermal responses and subsequent oxidation and ablation behaviors under the test conditions. • The comparisons and relationships of the oxidation and ablation behaviors for these thermal protection materials under extreme environments were illustrated. • The mechanisms for thermal responses, oxidation and ablation of these thermal protection materials were provided. Various thermal protection materials exhibit obviously different and complicated thermal response, oxidation and ablation behavior, which are very important for the appropriate design and selection. However, the relative researches are very few currently. In this work, the thermal response, oxidation and ablation behavior of representative thermal protection materials including ultra–high temperature ceramics, C/SiC, C/C, graphite and graphite–ceramic were investigated systematically in strong heat flux, high enthalpy and low-pressure environments. Thermal response of these materials was analyzed based on experimental results and thermal energy balance that accounts for all of the heat transfer processes transporting energy into and out of the surface. Many factors were playing important roles in the thermal response including thermal conductivity, volumetric heat capacity, catalytic efficiency, emissivity and oxidation characteristics of the materials. The importance of each factor not only depends on the material characteristics such as material composition and phase content but also environment parameters including heat flux, enthalpy, pressure and testing time. The comparisons and relationships of oxidation and ablation behaviors for these materials under extreme environments were also illustrated in detail. Furthermore, thermal response and ablation behaviors of pre–oxidized material or repeated tests were also performed to evaluate the effect of pre–treatment on the performance and reusability of thermal protection materials. This work offers guiding significance for the appropriate design and selection of thermal protection materials.

Research on the thermal shock simulation of the super high speed aircraft

Ultra high temperature ceramics (UHTC) with good mechanical properties and thermal physical properties, including high melting point (>30000C), high conductivity, high thermal conductivity, high thermal shock resistance rate, provides a sharp leading edge and smooth surface of a new generation of aerospace vehicle design to the aerospace industry; Due to ultra-high temperature ceramic materials with high strength, oxidation resistance and thermal shock resistance, it can be applied to extreme environments such as hypersonic flight, atmospheric reentry and rocket propulsion system, and have been widely used in key components of aircraft front cone, engine, wing and engine hot end. Based on the application of ultra-high temperature superconducting materials in practical application, the solid modeling of ultra-high temperature superconducting front-end components of ultra-high speed aircraft wing is carried out by using ABAQUS software, the ultra-high temperature thermal field of loaded aircraft flying at ultra-high speed is simulated, the stress-strain field at the flange is obtained, and the thermal mechanical coupling analysis is carried out.

Boronation reaction between molybdenum or tungsten powder and boron carbide in aluminium melt

Molybdenum or tungsten borides are excellent high-temperature ceramics or electrocatalysis materials. In this paper, Mo or W borides were prepared by boronizing Mo or W powder in Al melt with B4C as boron source. By thermodynamic calculation, the feasibility of preparing various borides and the stability of borides in Al melt were evaluated. Through high temperature reaction at 1523 K and the following acidic leaching, single phase MoAlB, W2B5, WB, and W2B5 powders were successfully synthesized. Owing to the decarburizing function of Al melt, C contents of various boride products were below 1 wt%. In addition, the phase transition processes of various products in the synthesis stage were revealed.

Spark plasma joining of HfB2-ZrB2 based Ultra High Temperature Ceramics using Ni interlayer

Real-life applications of ultra-high temperature ceramics (UHTCs) mandates the joining processes to realize the final complex shapes, often resulting in the compromised performance of metallic interlayer. In the present work, two pre-sintered HfB2-ZrB2 (HZ) and HfB2-ZrB2-SiC (HZS) composites were joined using interlayer of Ni powders via spark plasma sintering (1100 °C, 18 MPa). Solid-state diffusion of Ni into UHTCs has resulted in the formation of continuous and crack free interface in both HZ/Ni/HZ and HZS/Ni/HZS joints. Microstructure and phase analysis revealed the presence of nearly equal Ni-rich joint seam (∼100 μm) and diffusion zone width (∼150 μm) in HZ/Ni/HZ joint. However, prominent reaction of Ni with SiC in HZS composite has formed Ni2Si, while exhibiting wider diffusion zone (∼200 μm) and thinner Ni-rich joint seam (∼30 μm). Thus, microstructural inhomogeneity in HZ/Ni/HZ joint resulted in an overall reduction of ∼38% in hardness from parent HZ region (15.6 GPa) to Ni-rich joint (∼10 GPa), whereas for HZS, a uniform micro-hardness of ∼16 GPa was obtained in all the three regions owing to microstructural homogeneity across the interface. Damage tolerance of the joints has also been investigated by micro-scratch testing, revealing dominant abrasive wear in the parent UHTC region, whereas plastic deformation along with the tensile cracks is observed in the Ni-rich joint seam of HZ/Ni/HZ joint. In contrast, microstructural homogeneity in HZS/Ni/HZS joint has resulted in similar abrasive wear along with limited tensile cracks in all the regions, including that of Ni-joint seam, making it suitable for attaining superior structural integrity in joining complex shapes.

Research Status of Titanium Diboride High Temperature Ceramics

Titanium diboride has a series of excellent physical and chemical properties, high melting point and hardness, good thermal stability and oxidation resistance. As an excellent hard phase, titanium diboride is used in new materials such as composite materials and cermet. It has a wide prospect in the application of high-temperature ceramics. In this paper, the research status, performance structure, preparation method and application of titanium boride high-temperature ceramics are analyzed and summarized from the overall point of view, and the main problems faced by titanium boride at present are also discussed. Finally, the future research direction of titanium boride high temperature ceramics is discussed.