Abstract Semi‐rebonded periclase‐chromite refractories are commonly utilized in the working lining section of the molten pool in oxygen‐enriched top‐blowing furnaces for nickel production. Its resistance to nickel slag corrosion determines the safety and service life of the melting furnace. The composition of nickel slag influences the corrosion resistance of semi‐rebonded periclase‐chromite refractories. By comparing and analyzing specimens corroded by primary and modified nickel slag, the influence mechanism of w(CaO)/w(SiO2) variations on corrosion resistance of semi‐rebonded periclase‐chromite refractories was clarified. The results show that a spinel isolation layer is preferred to form at a lower w(CaO)/w(SiO2) ratio (< 0.576) and enhance the corrosion resistance of semi‐rebonded periclase‐chromite refractories. As the ratio increases, the slag viscosity falls and the corrosion products contain larger levels of Ca3Cr2Si3O12 and Ca3MgSi2O8, which prevent the creation of the isolation layer and establish a conduit for Ca2+ and Si4+ transport and reaction into the interior of the refractory.

Abstract In recent years, catalytic degradation driven by mechanical‐energy tribocatalysis has gained much attention. Point defects play very important on the catalytic activity of ferroelectric oxides. In this study, we focus on the influence of oxygen vacancies on the catalyst performance of ferroelectric oxide KSr 2 Nb 4 TaO 15 (KSNT) with a tetragonal tungsten bronze structure. The concentration of oxygen vacancies is modified by sintering atmosphere. The KSNT sintered in N 2 atmosphere exhibits the best tribocatalytic degradation efficiency of 96.7% within 2 h for degradation rhodamine B due to high concentration of oxygen vacancies. The excellent degradation efficiency is attributed to the defect energy level of KSNT and high electron–hole separation efficiency. This work reveals the relationship between oxygen vacancies and tribocatalysis efficiency, which is helpful to design and modify the new ferroelectric oxides for tribocatalysis.

Abstract Despite the favourable biomaterial properties of alumina ceramics in the last two decades, it revealed weak bioactivity in vitro and in vivo studies that limit the monolithic alumina ceramics for biomedical applications. CaTiO3 is a piezoelectric ceramic and has been reported as a high dielectric constant and a good substrate for apatite growth. This paper highlights the beneficial effect of adding CaTiO3 to alumina and encourages the development of electrically active biomaterial for bone replacement. In this regard, the alumina–calcium titanate (Al2O3–CaTiO3) composite was synthesized by sol–gel techniques. The densification of uniaxial pressed calcined sol–gel powders was sintered in a conventional furnace at a temperature of 1400°C for 2 hour. X‐ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were used to determine the phases and morphology of powders and sintered composite. The impedance analyzer was used to investigate the dielectric and electrical properties of the sintered composite. As a result, the phases of Al2O3 and CaTiO3 were retained and confirmed by XRD and SEM analysis. Impedance analysis indicates the decreasing trend of the dielectric constant and AC conductivity of the sintered sample with the function of frequency and temperatures. Finally, it can be concluded that the Al2O3–CaTiO3 composite could be potentially used as a functional biomaterial.

Abstract Silver ions possess inherent antioxidant properties, whereas hydroxyapatite (HAP) is a structural support within the body. The research methodology involves synthesizing HAP and 3% silver‐doped hydroxyapatite (Ag‐HAP) via the sol–gel method, followed by comprehensive characterization using X‐ray diffraction, Fourier transform infrared, Raman spectroscopy, and field emission scanning electron microscopy, antioxidant, thrombogenicity, and cell viability. The investigation reveals that Ag‐HAP exhibits superior antioxidant properties and thrombogenicity compared to other metals doped so far. Remarkably, Ag‐HAP demonstrates moderate clotting behavior compared to HAP. Additionally, the (3‐(4, 5‐dimethythiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide) MTT assay evaluates cellular viability, shedding light on the biocompatibility of the materials. The study uncovers the potential of silver doping to enhance the antioxidant capabilities of HAP significantly, offering promising prospects for orthopaedic implants. The antioxidant activity of the materials is evaluated through a 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging assay, whereas the thrombogenicity is assessed using a whole blood clotting method. The improvement indicates that incorporating silver ions influences HAP crystalline structure and increased grain size, contributing to enhanced antioxidant efficacy and favorable cellular responses, thus underlining the potential of Ag‐HAP for advanced implant materials in orthopaedic surgery. The results also discuss that how Ag‐HAP is better than Co‐HAP.

Abstract In this study, the evolutions of kinetic parameters, such as hydration temperature, pH, and electrical conductivity, were observed to investigate the hydration mechanism of hydrated magnesium citrate (HMC). Additionally, the effects of MgCl2 on the hydration behavior of HMC and the working performance of its bonded castables were also investigated. The results show that the hydration mechanism of HMC is dissolution–precipitation, and its hydration product is magnesium citrate tetrahydrate [Mg(H2O)6] [MgC6H5O7(H2O)n]2∙(8‐2n)H2O. The hydration process of HMC is controlled by the concentration of the C6H6O72− ions. MgCl2 could inhibit the ionization of HMC, thereby delaying the hydration progress of HMC. The second exothermic peak was delayed from 1 to 4.8 h with increased MgCl2 content to 1.0 wt.%. The working performance of HMC‐bonded castables could be improved by adding MgCl2. After adding MgCl2, the setting time, flow value, and cold modulus of rupture of HMC‐bonded castables increased by 26.7%, 25.2%, and 8.8%, respectively, while the porosity decreased by 12%.

Abstract The strength of zirconium diboride ceramics was tested by three different methods, 3‐point flexure, 4‐point flexure, and compression. Nearly full‐density ceramics were obtained by hot pressing commercial ZrB 2 powder with the addition of .5 wt.% carbon as a sintering aid. The thermal properties and hardness were studied for ZrB 2 milled with ZrB 2 and WC media. Based on phase purity and higher thermal conductivity, ZrB 2 ceramics prepared from powders milled with ZrB 2 media were selected for mechanical property studies. The strength in 3‐point flexure was 546 ± 55 MPa. The flexure strength was 476 ± 41 MPa in 4‐point bending, which was ∼20% higher than the previously reported value of 398 MPa for ZrB 2 with similar grain sizes due to higher relative density and lower impurity contents. Compression testing was performed at room temperature, and the strength was 1110 ± 358 MPa. Finally, the fracture toughness of pure ZrB 2 ceramics was determined by the chevron‐notched beam method to be 3.6 ± .7 MPa m 1/2 . The strength and fracture toughness values are higher than those previously published for ZrB 2 ceramics and can be attributed to higher density and lower grain size. The strength‐limiting flaw sizes were comparable to the grain size, suggesting that porosity and impurity phases did not play a significant role in the strength of these ceramics.

Abstract In the present study, SrTiO3 was selected to enhance the multiferroic characteristics of Bi0.88Sm0.12FeO3 (BSF) ceramics. With increasing SrTiO3 content, the principal phase of BSF ceramic transitions from rhombohedral R3c to Pna21. Through DSC and dielectric analysis, it was observed that both the Curie temperature and Néel temperature decreased proportionally with the augmentation of SrTiO3 content. When x = .1, the optimal ferroelectric performance is achieved, and the highest remanent polarization value is 55.47 µC/cm2, significantly surpassing that of BSF ceramics. Moreover, the PFM test results showed that as the substitution content increased, the domains in the BSF ceramic gradually transformed from normal ferroelectric domains to polar nanomicro‐domains. Magnetic and magnetoelectric results show that when x = .1, the best magnetic properties are obtained, Mr = 59.7 emu/mol. The magnetoelectric coefficient αME initially increased and then decreased with the increasing SrTiO3 content, reaching its optimum magnetoelectric properties at x = .1, where αME = .47 mV cm–1 Oe–1. In summary, when the substitution amount of SrTiO3 reaches 10%, the ferroelectric, magnetic, and magnetoelectric properties of BSF ceramics are significantly improved.

Abstract This study examines the effect of sintering mean residence time (MRT) on the engineering properties and morphological structure of lightweight aggregates (LWA) manufactured from waste coal combustion ash (W‐CCA). A thermodynamics‐based framework was used to tune LWA manufacturing processes. A minimum 35% liquid phase (by mass) and a lower bound viscosity of 100 Pa·s of molten material were found necessary to successfully produce LWA. Using W‐CCA's chemical composition and FactSage thermodynamic modeling, the sintering temperature for LWA was set to 1075°C. Green spherical pellets made using a pelletizer were sintered at MRT of 5.1, 14.8, and 25.9 min to test LWA physical‐mechanical properties including, unit weight, specific gravity, water absorption, and compressive strength. Results indicated that unit weight ranged from 752 to 800 kg/m3, providing desirable lightweight properties. Oven dry specific gravity ranged from 1.24 to 1.43, complying with ENI13055 specification for LWA. Water absorption capacity decreased as MRT extended from 5.1 to 14.8 min and then increased as MRT proceeded from 14.8 to 25.9 min, achieving an average absorption capacity of 26% ± 1.5%. The inverse effect was noticed for compressive strength as LWA sintered with an MRT of 14.8 min demonstrated the highest compressive strength of 14.7 ± 1.8 MPa. The initial decrease in water absorption and increase in compressive strength are attributed to the efficient sintering of the LWA's internal structure. The inverse effect observed as MRT proceeded from 14.8 to 25.9 min was believed to be a result of thermal cracking due to extensive heat exposure. MRT of 14.8 min is recommended for LWA production using the coal ash utilized in this study for its buoyancy characteristics, sufficient absorption capability, and higher compressive strength.

Abstract This paper aims to improve the density and thermal shock resistance of Y 2 O 3 ceramics for the preparation of ultra‐pure high‐temperature alloy crucible materials. The doping effect of MgF 2 content on the densification behavior, physical properties, and thermal shock resistance of Y 2 O 3 ceramics was systematically investigated in this paper. The results suggested that the presence of MgF 2 greatly promoted the growth of Y 2 O 3 grains and the transformation of the pore structure by liquid‐phase sintering. And the mechanical properties of the MgF 2 ‐doped Y 2 O 3 ceramics were significantly improved. Besides, the marked improvement in the thermal shock resistance of MgF 2 ‐doped Y 2 O 3 ceramics was attributed to the synergistic action resulting from the growth of grain size and the enhancement of the crack deflection effect. In particular, the relative density of Y 2 O 3 ceramics doped with 1.5 wt% MgF 2 reached 96.4% and the residual flexural strength ratio after thermal shock achieved 45.0%, showing an excellent application prospect.

Abstract This paper brings out an innovation in fabricating porous magnesia‐stabilized zirconia components by infiltrating free‐flowing suspension into polyurethane foam. The process enables the production of samples with different levels of porosity and pore structure by easily controlling the amount of slurry infiltrated into the foam. The process uses Isobam, a nontoxic binder, which makes the fabrication simple and environment‐friendly. Samples with five different levels of total porosity ranging from 41.7% to 62.4% were fabricated. Microstructural studies revealed multimodal pore structure comprising both open and closed porosities. Measurements on thermal properties and compressive strength of the samples showed that the sample with the lowest porosity exhibited a thermal conductivity of 0.495 W/mK and a compressive strength of 45.7 MPa. The measured values of thermal conductivity of the samples with different porosity levels could be described by modified effective medium theory. Present work opens up enormous possibilities for economical industrial production of porous magnesia‐stabilized zirconia components for biomedical and thermal insulation applications.