International Journal of Applied Ceramic Technology最新文献

Antiferroelectric (AFE) Pb_0.96La_0.04Zr_0.90Ti_0.10O₃ (PLZT) and AgNbO₃ (AN) ceramics were fabricated codoped with 1 mol% Er and various contents of Yb³⁺ ions. The ceramics exhibit good energy storage performances and electric-field-controlled photoluminescence (E-PL) intensity modulations, both of which are attributed to the reversible AFE-ferroelectric phase transition that accompanies a structural evolution. Accordingly, a noncontact energy charge/discharge monitor is proposed based on the E-PL effect, which is convenient and safe for the high-energy density capacitors. Besides, the PLZT and AN ceramics exhibit opposite E-PL behaviors that are caused due to different crystal space group transitions.

Carbon-bonded carbon fiber composites (CBCF) are renowned for their lightweight and thermal insulation properties. However, the brittleness and susceptibility to oxidation hinder the widespread application of CBCF. In this work, the carbon-bonded carbon/quartz hybrid fiber composites (CBCQF) were prepared by pressure filtration and modified by Cr₂AlC ceramics. The microstructure, mechanical properties, thermal insulation, and ablation behaviors were investigated. Cr₂AlC ceramics notably enhanced the compressive strength of CBCQF in the XY direction and reduced the room-temperature thermal conductivity in the Z direction. Most importantly, Cr₂AlC ceramics significantly improved the ablation resistance of CBCQF. When 40% Cr₂AlC ceramics were added, the linear and mass ablation rates of CBCQF were reduced by 38.0% and 93.2%, respectively, compared to the reference sample. Moreover, the study of ablation mechanisms revealed that the improvement in ablation resistance was primarily derived from the formation of the surface protective oxides as well as the reinforcement of oxidation resistance. Overall, this study presents a promising avenue for the application of Cr₂AlC ceramics and the modification of fiber composites.

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.

Ceramic saggars of mullite-cordierite are currently used to produce cathode powders for lithium-ion batteries. Strong interactions occur between the LiNi_0.8Mn_0.1Co_0.1O₂ (NMC) precursor in the temperature range of calcination (750–1000°C) leading to corrosion and formation of cracks in the saggar. The frequent failure of saggar causes a lot of waste, which could be reduced by choosing corrosion-resistant materials. To understand the corrosion mechanism in the system MgO–Al₂O₃–SiO₂, the materials MgO, Al₂O₃, MgAl₂O₄, and SiC (instead of SiO₂) were embedded in premixed NMC precursor and calcined at T = 780°C for 50, 100, 150 and 200 h. The formed phases were determined by phase and microstructure analysis. Finally, the formation of LiAlO₂ and Li₅AlO₄ is associated with a lower growth rate of the corrosion layer compared with Li₄SiO₄, while MgO is inert. The reactivity with NMC can be ordered as follows: SiO₂ > Al₂O₃ > MgO.

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%.

The tribological performance of the tungsten carbide substrate (WC-Co), improved by ceramic coatings, is still being reported in new studies that have been carried out to date. It has become a hot research topic that are widely applied in hard material research, especially in the tools manufacturing fields. This study was conducted to investigate the wear characteristics of a commercial cemented carbide tool (WC-Co) coated with a physical vapor deposition chromium-vanadium nitride film (CrVN), followed by a boriding process as a final thermochemical treatment. Tested in dry sliding contact against an alumina ball as a static partner, the tribological responses of the specimen were analyzed and compared with an uncoated specimen. Friction coefficients, calculated from volume loss, were around .58 for all specimens except the uncoated specimen at 10 N of applied load. Wear scar analyses revealed the occurrence of several wear mechanisms that is polishing, oxidation, wear debris formation, surface binder removal, grain fragmenting, and grain pull-out.

Digital light processing (DLP) three-dimensional printing has the advantages of both high printing resolution and efficiency and has been used to manufacture high-precision, small, and complex shaped ceramic parts. One of the challenges of DLP is to develop photosensitive ceramic slurries with high solid content and low viscosity, especially for non-oxide ceramics such as silicon nitride due to the dispersion and light absorption problem. This study mainly explores the dispersibility of silicon nitride in ultraviolet (UV)-cured resins and the photocured properties of the slurry. Rheological measurements were utilized to characterize and screen different dispersants in the resin. It was found that DISPERMP is an effective dispersant. In order to improve the curing depth of Si₃N₄ photosensitive paste, the surface of silicon nitride powder was treated by oxidation, and organic compounds with different refractive indices were also introduced to increase the light penetration depth. It was found that glycerol with a refractive index of 1.474 resulted in the greatest improvement in the curing depth of Si₃N₄ photosensitive paste. Finally, a proposed slurry composition was developed to successfully print silicon nitride ceramics through UV-curing molding technology.

Ceramic cores are the key components of precision casting hollow turbine blades, and 3D-printed silica-based ceramic cores are crucial to the development of the aerospace industry. However, silica-based ceramic cores have problems in terms of mechanical properties and friction properties. In this paper, silica ceramics were prepared by stereolithography-based 3D printing technology and processed at different sintering temperatures. The effect of sintering temperature on the microstructure, physical–mechanical properties, and friction and wear properties of the silica ceramics was investigated. The results show that, with the increase of sintering temperature, the average particle size and bulk density of the samples increased, while the open porosity and layer thickness decreased. The surface of ceramics became more and more flat with the increase in temperature. The flexural strength first increased with increasing temperature, and then suddenly decreased at 1350°C. The average surface roughness decreased with increasing temperature. The wear of the material decreased with increasing sintering temperature and increased at 1350°C. The optimum sintering temperatures were 1250°C and 1300°C, giving a flexural strength of 23.18 and 23.25 MPa, bulk density of 1.72 and 1.78 g/cm³, and open porosity of 24.49% and 23.66%, respectively.

The mechanical, thermophysical, and ablation properties of 2.5D C/HfC–SiC composites with various SiC/HfC ratios are studied. The S7-C/HfC–SiC composite with a high SiC/HfC volume ratio of 30.4/15.2 has the highest flexural strength of 203.4 ± 26.8 MPa and fracture toughness of 10.0 ± .5 MPa·m^1/2. All C/HfC–SiC composites have a similar low thermal conductivity of ∼2 W·m⁻¹·K⁻¹ and their CTEs are in the range of  .45–4.0 × 10⁻⁶/K from 30°C to 1400°C. S5-C/HfC–SiC with medium SiC/HfC ratio possesses the lowest mass ablation rate of  .29 ± .02 mg·cm⁻²·s⁻¹ and linear ablation rate of  .003 ± .0002 mm/s. The C/HfC–SiC composites are endowed with a pitting corrosion feature according to the morphology and composition evolution of the ablated surface, which results from both high temperature and stagnation pressure gradients in the radial direction of the oxyacetylene torch.

Oxidation resistance is crucial to the potential applications of high-entropy carbides (HECs) at elevated temperatures. Here, we realize the exploration of (Hf, Ta, Zr, Cr)C high-entropy carbides (HEC-TM, TM = Hf, Zr, Ta, and Cr) with good oxidation resistance by optimizing their compositions. To be specific, 21 kinds of HEC-xTM (x = 0–25 mol%) samples are fabricated by a high-throughput ultrafast high-temperature sintering technique, followed by oxidation testing at 1673 K for 30 min. Among all the HEC samples, the as-fabricated HEC-0Zr samples are proved to possess the best oxidation resistance with an oxidation depth of only 53 µm. Further study on isothermal oxidation kinetics demonstrates that the as-fabricated HEC-0Zr samples follow a linear oxidation law. The good oxidation resistance of the as-fabricated HEC-0Zr samples is believed to result from the (Ta, Me)₂O₅ phase with a low melting point, which can promote the densification of the oxide layer. This research opens up a new way for efficiently discovering new HECs for extreme applications.