Wen Liu

Zhengzhou University | zzu · School of Material Science and Engineering

In this work, multiwalled carbon nanotubes were introduced into polycarbosilane to fabricate carbon nanotubes reinforced nano-SiC composites (MWCNTs/ PCS-nano-SiC). Radiation effects on MWCNTs/ PCS-nano-SiC were studied by irradiation with 2 MeV Au²⁺ ions at room temperature and doses ranging from 2 × 10¹⁴ to 8 × 1014 ions/cm². The sample pyrolyzed...

CsPbX3 (X=Cl, Br, I) semiconductor nanocrystals (NCs) have excellent optical and photoelectric properties, and are potential core materials for various photoelectric devices. However, the toxicity of Pb and instability have been the key limitations to application of NCs. Herein, using MnBr2 and MnBr2·4H2O as manganese sources, heavy Mn-doped CsPbBr...

The dynamic transformations and damage behavior of free-standing multi-wall carbon nanotubes (MWCNTs), carbon nano-onions (CNOs), as well as nanodiamonds (NDs) are systematically studied by carrying out in-situ transmission electron microscope (TEM) measurements. Three key factors, including sp²-sp³ hybrid, inherent defects and morphology, are empl...

Flash sintering has been reported in various ceramics. Nevertheless, anion and cation conductors exhibit different flash-sintering behaviors, and the interaction mechanism between the conductive species and the sintering environment has remained unclear. Herein, we report the flash-sintering phenomena of a typical cation conductor, Na3Zr2(SiO4)2(PO...

The excellent physical and chemical properties of ultra-high temperature ceramics make them suitable for many high-temperature structural components, while their poor toughness and high sintering temperature become key limitations to their application. Laminated toughening has long been considered an effective toughening method to improve the mecha...

Electromagnetic absorption (EMA) materials with light weight and harsh environmental robustness are highly desired and crucially important in the stealth of high-speed vehicles. However, meeting these two requirements is always a great challenge, which excluded the most attractive lightweight candidates, such as carbon-based materials. In this stud...

Oxygen reduction reaction (ORR) occupies a pivotal position in fuel cell applications, and it is a challenge to obtain highly durable ORR catalysts. Herein, porous cobalt oxide microsphere growing at the surface of on nitrogen-doped graphitized-nano-diamond (CoO x /N-GND) was prepared using hydrothermal and subsequent heat treatment process. Porous...

Lithium titanium oxide (Li2TiO3) tritium breeder ceramic plates with nano- and coarse-grain size were fabricated. The preparation methods contained CTAB-modifying precursor, combining dry-pressing with isostatically cold-pressing, and calcinating at optimized sintering temperature in turn. Then their properties were characterized after radiation by...

In this paper, fully dense Si3N4/SiC nano-composites were fabricated through polymer-derived ceramics (PDCs) method and spark plasma sintering technique. Polymer-derived SiAlCN ceramic was synthesized by using polysilazane as preceramic precursor, aluminum tri-sec-butoxide as Al source. Then Si3N4/SiC composites with nanometer sized Si3N4 and SiC p...

CsPbX3 (X = Cl, Br, I) all-inorganic perovskite quantum dots have attracted extensive attention from researchers recently. However, the further development is confined by serious stability problems. In this work, the CsPbBr3 [email protected]2/EVA films were prepared by supersaturated recrystallization, and SEM, EDS, XRD, FT-IR and PL were used to...

The effects of high-energy ball milling (HEBM) on the sintering ability and microstructure of hafnium diboride (HfB2) ultrahigh-temperature ceramics (UHTCs) were investigated. After HEBM, the average particle size range of the HfB2 ceramics decreased to 10–20 nm with a slight alteration in the crystal structure. The microscopic grains of the sinter...

All-inorganic halide perovskite nanocrystals (NCs) are generally prepared by liquid phase method with the help of volatile organic solvents, inert gas protection and complex organometallic precursors. Herein, a simple, efficient and green method based on all-solid-state mechanochemical synthesis is proposed to prepare CsPbBr3 NCs. NCs with excellen...

Oxidation behavior of high-entropy carbide (Hf0.2Ta0.2Zr0.2Ti0.2Nb0.2)C (HTZTNC) was investigated over temperature range of 1400–1600 °C. Results showed improved oxidation resistance of high-entropy carbide compared with individual carbide ceramics. In oxide layer, Ta2O5 and Nb2O5 were found to be dominant phases at 1400 °C, whereas ZrTiO4 and HfTi...

Composites of g-C3N4 and vermiculite (gCNV–X, X = 10, 8, 6, 4, 2) with expanded vermiculite (VE) contents of 15.4%, 18.5%, 23.2%, 31.2%, and 47.6% were synthesized by a wet chemical method and provided confined space due to VE. Nanosheets or nanoparticles of g-C3N4 were homogeneously distributed in the gCNV–X composites. With increasing VE content,...

Highly pure and dense high entropy (Zr0.2Ta0.2Nb0.2Hf0.2Mo0.2)B2 ceramics have been obtained via oscillatory pressure sintering (OPS) at 1800 °C–1900 °C for 1 h under 30 ± 5 MPa. The formation of a single-phase solid solution was confirmed through XRD and TEM. The relative density and hardness of (Zr0.2Ta0.2Nb0.2Hf0.2Mo0.2)B2 sintered at 1900 °C ar...

Photocatalytic degradation of pollutants has been proved to be an effective strategy for wastewater treatment. Herein, TiO2 nanoparticles were synthesized on a Ti3C2 matrix by in situ growth, forming Z-scheme TiO2@Ti3C2/Cd0.5Zn0.5S (TO/CZS) multilevel structured nanocomposites via one-step hydrothermal route. The effects of hydrothermal temperature...

Two important performance parameters for lithium ion battery applications are capacity and cycle life, especially on fast charging. In this study, nano-crystalline graphite (NCG) uniformly dispersed in SiOC ([email protected]) was prepared via hydroboration of polysiloxane and acrylonitrile followed by heat treatment. The thermal annealing process...

A novel entropy-stabilized (ES) (Ca,Sr,Ba)ZrO3 ceramic has been designed and synthesized by pressureless sintering of CaZrO3, SrZrO3 and BaZrO3 powders mixtures at 1450 °C, 1500 °C and 1550 °C for 3 h. X-ray diffraction, scanning electron microscopy and transmission electron microscopy analyses collectively indicate that a single solid solution is...

In this work, high-entropy ceramics (Hf0.25 Zr0.25Ta0.25Nb0.25)C (HZTNC) and HZTNC doped with 20 vol% SiC (HZTNC-SiC) were fabricated by spark plasma sintering. Their oxidation behavior was investigated over the temperature range of 1300–1500 °C for up to 60 min. Both HZTNC and HZTNC-SiC exhibited good oxidation resistance, and their weight change...

A new high-entropy monoboride (Mo0.2Ta0.2Ni0.2Cr0.2W0.2)B ceramic with a WB-type orthogonal structure was designed and synthesised by in-situ reactive hot pressing at 2000 °C and 30 MPa for 1.5 h under an argon atmosphere. The microstructure of the sintered samples was comprehensively characterised, and the formation of a high-entropy monoboride (M...

In this work, high-entropy carbide (Hf0.2Ta0.2Zr0.2Ti0.2Nb0.2)C (HEC) ceramics doped with different concentrations of SiC were prepared by spark plasma sintering at 2000 °C in vacuum. Oxidation behavior of HEC ceramics was studied in 1300–1500 °C temperature range. The addition of SiC enhances oxidation resistance of HEC ceramics through the format...

Pressure measurement with excellent stability and long time durability is highly desired, especially at high temperature and harsh environments. A polymer-derived silicoboron carbonitride (SiBCN) ceramic pressure sensor with excellent stability, accuracy, and repeatability is designed based on the giant piezoresistivity of SiBCN ceramics. The SiBCN...

Among the various concepts of SiC-based accident-tolerant fuel cladding, duplex SiC cladding, consisting of an inner composite layer and an outer monolithic SiC layer, is considered an optimal design due to its low load failure probability. In this study, SiC nanowires (SiCnw) were introduced on the substrate graphite rod to decrease the diameter o...

The electric conductivity of zirconia in the steady stage of flash sintering is measured under various current densities. We find that the steady stage conductivity (σs) is higher than the normal conductivity (σn) measured at non-flashing conditions, even Joule heat is considered. The higher conductivity is ascribed to the increase in charge carrie...

Compared to densification process for SiC matrix to obtain nuclear-grade SiC fiber-reinforced SiC matrix (SiCf/SiC) composites, it would be time-saving and less expensive to employ spark plasma sintering (SPS) process for the densification of nuclear-grade SiC fiber-reinforced Ti3SiC2 matrix (SiCf/Ti3SiC2) composites. In this work, Ti3SiC2 matrix w...

In this study, Mo–W–Mo multi-interlayers were used to develop a diffusion bond with SiC-coated three-dimensional (3D) C/SiC composites by spark plasma sintering (SPS). The interfacial microstructure and the phase composition of the joints were investigated. Appropriate interfacial reaction resulted in higher interfacial bonding strengths (shear str...

SiC-coated three-dimensional (3D) C/SiC composites were successfully joined with a Ni-Ti-Nb multi-interlayer by spark plasma sintering (SPS). The interfacial microstructure, phase evolution, and mechanical properties of the as-prepared joints were investigated. A sawtooth-like interfacial structure was generated as a result of the non-uniform disso...

Ultra-wide absorption bandwidth is one of the goals of ideal absorbing materials. In this article, three-dimensional porous microstructure Co/SiCN ceramic aerogel composites (CACs) were synthesized through a reverse microemulsion method, which is aimed to avoid the aggregation of cobalt nanoparticles, and makes better impedance matching between CAC...

Immobilization of radionuclides by more feasible and efficient methods is crucial for dealing with ever-increasing quantities of radioactive nuclear waste. Immobilization of simulated radionuclide Nd through formation of zirconium-based ceramics by flash sintering has been investigated for the first time in this report. A mixture of zirconia, neody...

This work describes an electric-field assisted joining technique that is capable of joining 3 mol.% yttria stabilized zirconia (3YSZ) ceramics within 1 min at furnace temperature of 400 °C. The joint with 94–99% of the parent material's three-point bending strength (638 ± 21 MPa) was achieved at furnace temperature of 600–900 °C by optimizing the k...

Rod-like ZrB 2 crystals were synthesized at 1600 °C in Ar atmosphere by boro/carbothermal reduction using ZrOCl 2 ⋅8H 2 O, B 4 C and carbon powders as raw materials. The optimum molar ratio of raw materials required to form pure ZrB 2 grains was found to be 2: 1.2: 3. With increase in temperature and subsequent heat preservation stage, ZrB 2 powder...

Dense ZrB2‐SiC‐Al3BC3 ultra‐high temperature ceramic composite was fabricated by hot pressing sintering at 1900°C for 1 hour under a pressure of 20 MPa using Zirconium diboride (ZrB2) as the raw material and a powder mixture of SiC, B4C, Al, and carbon as the sintering additive. Al and B4C underwent in situ reaction with carbon powder to produce Al...

Dense Boron-doped diamond (BDD) composites were fabricated by high pressure and high-temperature sintering (HPHT) at 5 GPa and 1450 °C for 300 s in presence of Al, B and C as sintering additives. Phase compositions, microstructures, and electrochemical performances of sintered specimens were investigated by X-ray diffraction (XRD), scanning electro...

A significant decrease in the thermal conductivity of SiC after irradiation has hindered its practical applications. To solve this problem, polymer-derived pure SiC and C-SiC composites were irradiated under 4 MeV Au²⁺ ions, and their thermal conductivity was evaluated. The time-domain thermoreflectance method was found to be effective and sensitiv...

Polymer-derived SiC ceramics have been increasingly used in the field of nuclear energy. Herein, we synthetized polymer-derived SiCs with varying SiC/C heterogeneous interfacial properties by pyrolyzing the ceramics at different temperatures. Subsequently, we studied the effect of these interfacial properties on the irradiation behavior (i.e., volu...

The development of reaction-bonded SiC (RB-SiC) for an application in nuclear reactor environments has been suspended for many years because of the possible swelling mismatch between SiC and Si under irradiation. Therefore, we studied the residual stresses in RB-SiC due to the irradiation-induced swelling mismatch and the mismatch between the coeff...

The microstructural effects of SiC swelling, mechanisms of He diffusion and aggregation in C-rich SiC are studied using an in situ helium ion microscope. The additive carbon interface provides improved swelling resistance in SiC to ∼270 nm, and defect formation is not observed until very high He implantation doses.

Magnetic CoFe2O4-containing silica with an ordered mesoporous structure was prepared by the self-assembly associated with triblock copolymer, tetraethyl orthosilicate, ferric nitrate and cobalt nitrate. Ammonia water was added to adjust the pH value for collecting the mixture, and then the products were obtained at various temperatures in air. The...

Luminescence of europium-doped yttrium phosphate (YPO4:Eu) environmental barrier coatings (EBCs) has been developed as a means of self-monitoring. The corrosion behavior of YPO4:Eu in water vapor and molten salt is investigated as well as the effect of these corrosion environments on the intensity of luminescence. By comparison of these results, th...

A non-silicate material, yttrium phosphate (YPO4), is developed for the application as environmental barrier coatings. The key issues of environmental durability, phase stability, chemical compatibility, and coefficient of thermal expansion (CTE) are considered for the selection of YPO4. The water corrosion behaviors for the sol–gel prepared YPO4 w...

Two-dimensional C/ZrB2-SiC composites were fabricated by chemical vapor infiltration (CVI) process combined with slurry paste (SP) method. ZrB2 was introduced in the matrix by stacking the pasted carbon cloth with ZrB2-polycarbosilane slurry. After heat-treated at 900 °C, the stacked carbon cloth preform was infiltrated SiC by CVI process to obtain...