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Lightweight phenolic matrix composites are highly potential in ablative thermal protective materials for future aerospace vehicles, and hybrid modification is considered as one of effective ways to improve the oxidation and ablation resistance of phenolic matrix. Herein, the co-continuous silica zirconium hybrid phenolic resin (SZRx) was synthesized, which can be used to prepare lightweight ablation resistant aerogel composites by the sol-gel method. The SZRx aerogel showed stable porous structure and excellent hydrophobicity, and the silicon zirconium hybrid greatly improved the high temperature carbon residue and oxidation resistance of phenolic resin. The SZRx aerogel composites also possessed excellent integrated characteristics of heat protection and insulation, with a linear ablation rate as low as 0.032 mm/s and a back temperature below 200 °C. The synergistic effect of silicon and zirconium formed the multiphase ceramic layer (C, SiO 2 , SiC and ZrO 2) with the sea-island-like structure on the surface of the composite material, which can effectively resist high-temperature ablation and aerodynamic exfoliation. This can indicate that silicon zirconium dual element hybrid phenolic resin is the highly competitive matrix for lightweight and ablation resistant composite materials. [Display omitted] [ABSTRACT FROM AUTHOR]

The manuscript presents the synthesis and dry sliding wear performance of Al7075 alloy‐based composites. Five compositions namely Al7075 alloy, Al7075+3 vol % molybdenum disulfide, Al7075+3 vol % molybdenum disulfide+3 vol % zirconium diboride, Al7075+3 vol % molybdenum disulfide+6 vol % zirconium diboride and Al7075+3 vol % molybdenum disulfide+9 vol % zirconium diboride were stir cast and characterized for hardness, x‐ray diffraction, microstructure, and tribological properties. In‐situ formed zirconium diboride particles increase the hardness of Al7075 alloy whereas molybdenum disulfide shows the opposite trend due to its self‐lubricating nature. X‐ray diffraction analysis identifies subsequent phase particles in the matrix while microstructural images exhibit the dispersion and morphology of reinforcement particles. The wear tests and friction coefficient were analyzed with variations of sliding velocity, normal load, sliding distance, and compositions. Further, the obtained wear results were also correlated with microstructure and wear surface topography. Al7075+3 vol % molybdenum disulfide composite shows the lowest coefficient of friction because of its self‐lubricating nature. Al7075+3 vol % molybdenum disulfide+9 vol % zirconium diboride hybrid composite exhibits the lowest wear rate at high velocity as well as at high load and can be potentially used in manufacturing and tribological applications. Moreover, the use of this material may lead to the minimum requirement of external toxic lubricants that make it cost‐effective and environmentally sustainable. [ABSTRACT FROM AUTHOR]

Sulfuric acid corrosion is a non-negligible problem affecting the durability of concrete materials. To explore the mechanism of sulfuric acid corrosion on the fracture performance and microstructure of concrete, three-point bending test was utilized to analyze the evolutionary characteristics of the crack mouth opening displacement and the fracture toughness of concrete corroded by sulfuric acid. Scanning electron microscope and energy-dispersive spectrometer were utilized to analyze the characteristics of microscopic morphology and corrosion products of concrete corroded by sulfuric acid. The result shows that the fracture evolution of concrete can be divided into four stages: nonlinear development stage, linear development stage, deceleration expansion stage, and accelerated expansion stage. In purified water environment, the peak fracture load and fracture toughness of concrete is positively related to corrosion time. In sulfuric acid corrosion environment, the peak fracture load and fracture toughness of concrete are negatively related to corrosion time and concentrations of sulfuric acid solution. Microscopic experiments show that the interior of concrete is less affected by sulfuric acid corrosion, and the structure is relatively dense compared with the surface. The expansion crystal ettringite formed at the fracture surface of the concrete specimen during sulfuric acid corrosion was the main reason for the durability reduction of concrete. [ABSTRACT FROM AUTHOR]

A novel technique to simultaneously lower the synthesis temperature of highentropy carbides and maintain their high mechanical properties was proposed. Certain amount of carbon vacancies was first introduced to significantly lower the temperature down to 2000°C for uniform elemental distributions in highentropy carbides. Those carbon vacancies were then fully eliminated through the reaction between high-entropy carbides and certain amount of boron carbide. Concomitantly, the high-entropy boride phasewas formed. The elimination of carbon vacancies and the formation of high-entropy boride phase significantly improved the mechanical properties of the high-entropy carbides. A high mechanical strength over 500 MPa can be obtained by phase optimization. [ABSTRACT FROM AUTHOR]

In fiber-reinforced components, the fiber alignment and orientation have paramount influence on the thermo-mechanical properties of the resulting composite, for both short and continuous fiber. Here we present the case of an ultra-refractory matrix intended for extreme environment applications, ZrB 2 , reinforced with 20 vol% and 50 vol% short carbon fibers. In both cases, fibers tend to align perpendicular to the uniaxial pressure applied during shaping and sintering of a pellet, although the fiber tilt across the pellet thickness is difficult to determine. Moreover, for high volume fractions of reinforcement, the spatial distribution of the fibers is heterogeneous and tends to have domains of preferential orientations. We compare the information on the fiber distribution as collected by scanning electron microscopy images, X-ray computed tomography and synchrotron X-ray refraction radiography (SXRR). The three techniques prove to be complementary. Importantly, we demonstrate that SXRR yields the most statistically significant information due to the largest field of view, yet with a sensitivity down to the nanometer, and that can be successfully applied also to heavy matrix materials, such as zirconium boride. [ABSTRACT FROM AUTHOR]

With the vigorous development of the Internet of Things, 5G technology, and artificial intelligence, flexible wearable sensors have received great attention. As a simple and low-cost power supply in wearable sensors, the triboelectric nanogenerator (TENG) has a wide range of applications in the field of flexible electronics. However, most polymers are thermally poor conductors (less than 0.1 W/(m·K)), resulting in insufficient heat dissipation performance and limiting the development of TENG. In this study, a high-performance non-woven fabric TENG with strong thermal conductivity (0.26 W/m·K) was achieved by introducing ZrB2 into the polyurethane (PU) matrix. The excellent output performance with an open circuit voltage (Voc) of 347.6 V, a short circuit current (Isc) of 3.61 μA, and an accumulated charge of 142.4 nC endows it with good sensitivity. The electrospun PU/ZrB2 composites exhibit excellent sensing performance to detect body movements in situ, such as pressing, clapping, running, and walking. Moreover, the generated power can light up 224 LED bulbs as a demonstration of self-powering ability. [ABSTRACT FROM AUTHOR]

This paper deals with the synthesis of a series of zirconoaluminosiloxane (ZAS) as monophasic liquid precursors in toluene for zirconia/mullite ceramics. Precursors are synthesized by the zirconium modification of aluminosiloxane. The effect of zirconium incorporation in the aluminosilicate network is studied by FTIR, NMR, and TG/DTA analysis. 29Si and 27Al clearly indicates that zirconium is chemically bonded to the aluminosilicate network and the network connectivity increases with increase in zirconium content. 27Al NMR also reveals the progressive distortion of octahedral symmetry of AlO 6 due to zirconium incorporation, validating the insertion of Zr through Al–O–Zr bonds where Al is four coordinated. These observations attest the monophasic nature and the chemical homogeneity of the synthesized precursors, which is the main factor contributing to the low temperature crystallization of ceramic phases. Ceramic conversion studies of the precursors confirmed the formation of crystalline zirconia/mullite ceramic phases at a low temperature of 900 °C. The XRD and microstructure analysis by SEM/EDX indicated that the mullite crystallization can be controlled by zirconia incorporation. This effect is discussed in terms of the occupancy of zirconia either as intra-granular or inter-granular particles. The zirconia concentration for maximum crystallization of mullite is optimized. [Display omitted] [ABSTRACT FROM AUTHOR]

There are many great uses for heavy elements that are expanding daily and generating enormous amounts of effluents. Therefore, tremendous scientific efforts in removing, recovering, and recycling them are carried out to prevent these harmful effects on the environment and human health. The polyacrylic-carboxymethyl cellulose-trioctyl amine/reduced graphene oxide adsorbent (AA-CMC-TOA/rGO) was synthesized as a promising sorbent for Zr4+ and Y3+ ions by gamma irradiation for a mixture of acrylic acid, carboxymethyl cellulose, and trioctyl amine as an organic solvent. A complete characterization of the manufactured composite was carried out to find out its chemical and physical properties several techniques such as XRD, EDX, SEM, FT-IR, TGA-DTA, and BET. Several factors affecting the Zr4+ and Y3+ adsorption processes were studied to set the best conditions that achieve the extreme loading capacity of Zr4+ and Y3+ ions. Loading capacities of 0.99 and 1.07 mmol g−1 were achieved for Zr4+ and Y3+, respectively. The results of the kinetic models indicated that the adsorption reactions of Zr4+ and Y3+ ions were carried out via a chemical reaction mechanism. Langmuir, Dubinin–Radushkevich, and Redlich–Peterson models accurately described the adsorption isotherm data by proving their chemical nature. The results of thermodynamics added evidence of the chemical nature, spontaneous, and endothermic nature of the adsorption processes. A complete retrieval for Zr4+ and Y3+ ions contents located in the effluent was efficiently achieved using AA-CMC-TOA/rGO sorbent which proved its uses as a promising sorbent. [ABSTRACT FROM AUTHOR]

Bioinert materials such as the zirconium dioxide and aluminum oxide are widely used in surgery and dentistry due to the absence of cytotoxicity of the materials in relation to the surrounding cells of the body. However, little attention has been paid to the study of metabolic processes occurring at the implant–cell interface. The metabolic activity of mouse 3T3 fibroblasts incubated on yttrium-stabilized zirconium ceramics cured with aluminum oxide (ATZ) and stabilized zirconium ceramics (Y-TZP) was analyzed based on the ratio of the free/bound forms of cofactors NAD(P)H and FAD obtained using two-photon microscopy. The results show that fibroblasts incubated on ceramics demonstrate a shift towards the free form of NAD(P)H, which is observed during the glycolysis process, which, according to our assumptions, is related to the porosity of the surface of ceramic structures. Consequently, despite the high viability and good proliferation of fibroblasts assessed using an MTT test and a scanning electron microscope, the cells are in a state of hypoxia during incubation on ceramic structures. The FLIM results obtained in this work can be used as additional information for scientists who are interested in manufacturing osteoimplants. [ABSTRACT FROM AUTHOR]

(LaO 1.5) x (ErO 1.5) x (YO 1.5) 0.03 - 0.5 x (ZrO 2) 0.97- x ceramics with high density (98.1 %), high strength (1533 MPa), high surface residual stress (1305 MPa) and fine grain (96 nm) were prepared by ultra-low temperature hot pressing sintering. The results indicate that high pressure significantly promotes densification in the contact area of (LaO 1.5) x (ErO 1.5) x (YO 1.5) 0.03 - 0.5 x (ZrO 2) 0.97- x ceramics particles and no effect on grain growth. Low temperature can effectively reduce the transition from tetragonal to cubic phase (T-C) and limit grain growth. In addition, 1305 MPa compressive stress on the surface of (LaO 1.5) x (ErO 1.5) x (YO 1.5) 0.03 - 0.5 x (ZrO 2) 0.97- x ceramics were the main reason for the improvement of bending strength. This process provides a design idea for obtaining fine-grained fully dense structural ceramics. [ABSTRACT FROM AUTHOR]

(LaO 1.5) x (ErO 1.5) x (YO 1.5) 0.03 - 0.5 x (ZrO 2) 0.97- x ceramics with high density (98.1 %), high strength (1533 MPa), high surface residual stress (1305 MPa) and fine grain (96 nm) were prepared by ultra-low temperature hot pressing sintering. The results indicate that high pressure significantly promotes densification in the contact area of (LaO 1.5) x (ErO 1.5) x (YO 1.5) 0.03 - 0.5 x (ZrO 2) 0.97- x ceramics particles and no effect on grain growth. Low temperature can effectively reduce the transition from tetragonal to cubic phase (T-C) and limit grain growth. In addition, 1305 MPa compressive stress on the surface of (LaO 1.5) x (ErO 1.5) x (YO 1.5) 0.03 - 0.5 x (ZrO 2) 0.97- x ceramics were the main reason for the improvement of bending strength. This process provides a design idea for obtaining fine-grained fully dense structural ceramics. [ABSTRACT FROM AUTHOR]

Zirconia (ZrO 2) aerogels have the potential to service at temperatures exceeding 1000 °C, exhibiting superior insulation performance over those of silica, alumina and carbon aerogels, etc., but the zirconium chloride based salts, such as zirconium oxychloride, with overfast phase separation rate and indelible chlorine impurities, impede the development of an economic and environmentally benign synthesis. Besides, the stabilities of ZrO 2 aerogels toward high temperature exposure need to be further improved. With these regards, in this work, zirconium hydroxyacetate was brought up for the first time to produce ZrO 2 aerogel with the aid of a tailor-made sol-gel chemistry. Polar solvents were found to be efficient in manipulating the phase separation. After depositing silica to the gel network, ZrO 2 aerogels with a maximum visible light transmittance of up to 90 %, compressive strength of 0.24 MPa (0.159 g‧cm−3) were successfully obtained. The thermal conductivity of the aerogel reached a recorded value of 9.67 mW‧m−1‧K−1 at room temperature. The resultant aerogels possess a uniform skeleton structure with pore distribution below 20 nm, and can retain their mesoporous structure at 1000 °C, keeping a specific surface area of 200 cm2‧g−1. This work presents a well-established procedure for synthesizing high-quality ZrO 2 aerogels and promotes their utilization in optics, thermal insulation, and other related fields. [ABSTRACT FROM AUTHOR]

The preparation of high-performance Al 2 O 3 -ZrO 2 fibers is a significant and challenging task. In this study, continuous Al 2 O 3 -ZrO 2 fibers were synthesized via the sol-gel method using aluminum powder and zirconium acetate as raw materials. It was observed that the amorphous state of Al 2 O 3 transformed into γ-Al 2 O 3 and then to α-Al 2 O 3 , while the amorphous ZrO 2 directly transformed into t-ZrO 2. The formation temperatures of t-ZrO 2 and α-Al 2 O 3 were both approximately 1100 °C. The optimal sintering temperature during the single-step sintering process for Al 2 O 3 -ZrO 2 fibers was 1400 °C. Based on the experiment results, fully dense Al 2 O 3 -ZrO 2 fibers with fine grains were successfully synthesized via a two-step sintering process. The average sizes of Al 2 O 3 and ZrO 2 grains were 153 nm and 62 nm, respectively. The Weibull strength of the Al 2 O 3 -ZrO 2 fibers reached 2.2 GPa with a peak value of 2.6 GPa, which exhibited an increase of approximately 30% compared to that formed by the single-step sintering process. Furthermore, the nucleation, growth, and densification behaviors of Al 2 O 3 -ZrO 2 fibers during the two-step sintering process were discussed. [ABSTRACT FROM AUTHOR]

Understanding the structural and thermoelectric (TE) properties of a pure material is essential for developing a practical approach to improve its TE performance. This study focuses on the high-temperature TE properties of ZnO ceramics synthesized by the spark plasma sintering (SPS) technique. The analyses of crystallinity and microstructure along with photoluminescence and Raman spectroscopy indicated an increase in oxygen vacancy in the ZnO ceramics with SPS temperature, which resulted in unit-cell shrinkage, lattice modification, grain densification, and TE modification. Specifically, oxygen vacancies were found to be a crucial factor affecting the TE performance of the spark-plasma-sintered ZnO ceramics at temperatures exceeding 773 K. Oxygen vacancies can act as carrier donors when they are ionized, contributing to an increase in electrical conductivity and a decrease in thermal conductivity. Additionally, this study proposes a potential way to engineer native defects in ZnO ceramics by controlling the SPS process. [ABSTRACT FROM AUTHOR]

In order to explore the influence of freeze-drying process parameters on the size of zirconium phosphate (α-ZrP) nanoparticles during freeze-drying, different process parameters were selected and orthogonal experiments were designed to prepare nano α-ZrP with different particle sizes. The structures of nano α-ZrP are characterized by the field emission scanning electron microscope (SEM), and the tribological properties of nano α-ZrP are studied on a tribometer. The orthogonal experimental results indicated that the order of process parameters affecting the size of nano α-ZrP is freezing method > material tray area > reaction temperature. The freezing method has the greatest influence on the size of nano α-ZrP. The particle size is around 20 nm under vacuum freezing, 40 nm under liquid nitrogen freezing, and 60 nm under refrigerator freezing. The reaction temperature of 98 °C, the material disk area of 80 mm2, and vacuum freezing were found to be the optimal process parameters for the preparation of small size nano α-ZrP by freeze-drying. Different amounts of granular nano α-ZrP were added to the base oil; when the addition amount was 2%, the friction coefficient was the smallest, which could be reduced by 34.6%. Friction experiments were conducted on three distinct morphologies of nano α-ZrP (granular, lamellar, and rod); the results show that the friction performance of nano α-ZrP with granular morphology is better than that of the other two crystal morphologies. [ABSTRACT FROM AUTHOR]

The preparation process for the composites CuO/ZnO/γ-Al2O3, which can be used as the main component of catalysts for large-tonnage methanol production and carbon monoxide conversion, was investigated by means of x-ray phase, x-ray crystalline, and synchronous thermal analysis as well as scanning electron microscopy, and low-temperature adsorption-desorption of nitrogen. The influence of the production method and the nature and intensity of processing on the phase composition of the resulting precursors and the physicochemical properties of the resulting composites was determined. The processes occurring at the stage of mechanochemical activation of a mixture of anhydrous oxides CuO/ZnO/γ-Al2O3 and a mixture of oxides with ammonium carbonate and ethanedioic [oxalic] acid were studied. The optimal parameters for obtaining CuO/ZnO/γ-Al2O3 composites with a developed specific surface and porous structure were determined. [ABSTRACT FROM AUTHOR]

This article investigates the effect of the time of aging of ZrO2 powders, obtained from zirconium butoxide sols, stabilized using complexating agents on the volume phase fractions tetragonal phase (T) and baddeleyite crystalographic phase (B), pore size distribution and pore volume. It was proved that the aging time period influences ratio between these two polymorphs of zirconia. The sample Zr3d possesses the largest content of baddeleyite phase having the greatest crystallites in comparison to another two powders. The increasing of aging period leads to a gradual increase in (101) peak intensity of T phase, while all the samples are microporous regardless of the aging time. The longest time aged sample possesses higher pore volume and higher average pore diameter than the other two powders. The physico-chemical features of the prepared ZrO2 nanosized powders could be beneficial as catalysts/photocatalysts in different catalytic reactions, corrosion inhibition particles, etc. [ABSTRACT FROM AUTHOR]

The rupture of a micro/nano container can trigger the release of repair agents and provides the coating with a self-healing and anti-corrosion effect. However, the defect and inhomogeneity of the coating, produced by the rupture of the micro/nano container, may weaken its anti-corrosion performance. This study reports a rare protection mechanism, which optimizes the space occupying of zirconium phosphate, and the de-doping peculiarity of polyaniline without the rupture of the micro/nano container. Polyaniline/α-zirconium phosphate composites were constructed through in situ oxidation polymerization. Repair agents were added in the form of doped acids. According to the different repair agents in polyaniline/α-zirconium phosphate composites (citric ion, tartaric ion and phytic ion), the performance and protection mechanism of the composites were researched. Polyaniline/α-zirconium phosphate coating (with phytic ion) shows an excellent self-healing anti-corrosive effect, due to the large spatial structure and abundant chelating groups of the precipitation inhibitor. Considering the anti-corrosive application, the developed polyaniline/α-zirconium phosphate composite has a far-reaching influence on marine development. [ABSTRACT FROM AUTHOR]

Zirconium-based MOFs, such as PCN-222 (MOF-545), have gained attention due to their regular porosity, tuneable pore size, versatile structure and exceptional thermal/chemical stability. However, the synthesis of PCN-222 using traditional batch processes suffers from limitations in productivity, scalability, and control over size and morphology. This study presents a paradigm shift from batch to continuous flow (c.f.) synthesis for the efficient production of PCN-222. The optimization of batch conditions and exploration of c.f. parameters enabled the synthesis of high-quality PCN-222 with Space–Time–Yield (STY) exceeding 950 kg m−3 day−1. The c.f. approach offered advantages including improved resource efficiency, safer chemical handling, and scalability. The integration of ultrasound-assisted technique into the c.f. facilitated the shaping of PCN-222 into prolate ellipsoids, making it suitable for applications in drug delivery and catalysis. The successful substitution of hazardous solvents with greener alternatives further enhanced the sustainability of the process. Finally, the loading of a thio-N-acetylgalactosamine-PEG-sulfate ligand on PCN-222 in tandem c.f., expanded the potentialities of the flow synthetic approach. This study not only advances the field of MOF synthesis but also paves the way for efficient and sustainable manufacturing processes in c.f. synthesis of nanoparticles and functionalized nanoparticles for active drug delivery. [ABSTRACT FROM AUTHOR]

A UiO-67-type Zr-based metal–organic framework (MOF) with dibenzothiophene linkers, UiO-67-S, was synthesized using a solvothermal method. The crystal structure of UiO-67-S exhibits the same topological structure as UiO-67 and its derivatives. UiO-67-S shows high thermal stability and excellent permanent porosity. Moreover, its excellent hydrogen storage indicates that the thiophene moiety is suitable for enhancing the hydrogen storage ability of MOFs. [ABSTRACT FROM AUTHOR]

Xerogels and powders of a solid solution based on zirconium dioxide are synthesized by the method of coprecipitation of hydroxides from aqueous solutions of salts of zirconium nitrate ZrO(NO3)2⋅2H2O, aluminum Al(NO3)3⋅9H2O, and cerium Ce(NO3)3⋅9H2O with an aqueous 1 M solution of ammonia NH4OH. A dense ceramic with low porosity and water absorption is obtained. The effect of the ultrasonic treatment of the precipitate and mechanical treatment of the xerogel on the physicochemical properties of the obtained materials is evaluated. [ABSTRACT FROM AUTHOR]

External sulphate attack (ESA) interferes with spatial changes in fracture toughness of cemented paste backfill (CPB) and affects its mechanical stability. Large-scale curing column models are developed to investigate the spatial evolution of mode-I and mode-II fracture toughness (i.e. KIC and KIIC) under seepage- and diffusion-induced ESA. It has been found that the seepage-induced ESA leads to spatial changes in KIC and KIIC of CPB at advanced ages and higher extent of degradation of fracture toughness is measured at a deeper position in CPB. Comparatively, KIc can be used as a reliable quantity to estimate KIIc under the diffusion-induced ESA. [ABSTRACT FROM AUTHOR]

Zirconia–silica monolithic catalysts with hierarchical micro/macroporous structure were obtained in a sol-gel process combined with phase separation using inorganic salts, i.e., oxychloride, oxynitrate and sulphate, as a zirconium source. It was found that the use of zirconium oxychloride and prehydrolysis of tetraethoxysilane (TEOS) resulted in materials characterized by a well-developed continuous structure of macropores with a diameter of ca. 10 μm. For zirconium oxynitrate and sulfate modified materials, the prehydrolysis hardly affected the macropore size. The micropores with a diameter of 1.5 nm in the skeleton of all materials provided a large surface area of 550–590 m2/g. A high dispersion of zirconia in the silica skeleton in all studied materials was shown. However, the largest surface concentration of Lewis and Brönsted acid sites was found in the monolith synthesized with zirconium oxychloride. The monoliths were used as a core for continuous-flow microreactors and high catalytic activity was confirmed in the deacetalization of benzylaldehyde dimethyl acetal. The process was characterized by a high efficiency at low temperature, i.e., 35 °C. [ABSTRACT FROM AUTHOR]

A new type of cermet coating, with potential use as low-cost solar thermal absorber has been developed using spray pyrolysis. It consists of crystalline silver nanoparticles embedded in amorphous zirconia and was obtained by spraying aqueous precursor solutions onto aluminized carbon steel sheets at 200 °C. It was found that simultaneous spraying of silver and zirconium solutions led to a considerable reduction, in the nanometer range, of silver particle size distribution. Hence, we comparatively studied the cermet coatings obtained by A) sequentially or B) simultaneously spraying silver and zirconium solutions. For the latter case, a zirconia anti-reflection layer was sprayed on top. Both coating systems were studied by SEM, AFM, HRTEM/EDS and UV-VIS-IR spectroscopy with respect to silver particle size distribution. Optical parameters like solar absorptance (AM 1.5) and thermal emittance (373 K) were determined from absolute hemispherical reflectance, and a performance coefficient was calculated in order to evaluate the solar selectivity of the coatings. The comparison showed that smaller silver particles lead to an increase in solar selectivity and that the size reduction is due to an effective encapsulation by zirconia of the silver particles when spraying silver and zirconium precursors simultaneously. Furthermore, HRTEM confirmed the metallic and crystalline state of the silver nanoparticles embedded in amorphous zirconia. [ABSTRACT FROM AUTHOR]

In Part 1 of this study, we investigated the macrokinetic parameters and phase formation mechanism in the combustion front of Zr–Nb–B mixtures. In the second part, we produced consolidated samples of solid solutions NbB 2 -(0.100%)ZrB 2 by hot pressing the combustion-derived powders at 1900 °C. By measuring the crystallographic parameters, mechanical and thermophysical properties of the produced bulk samples, we obtained valuable insights into the behavior of the solid solutions. Our results pave the way for the application-specific fine-tuning of the mechanical properties and thermal conductivity of diboride solid solutions in the Zr–Nb–B system for ultra-high temperature applications. Our findings have significant implications for the development of advanced materials with outstanding performance in extreme environments. [ABSTRACT FROM AUTHOR]

The self-propagating high-temperature synthesis (SHS) in Zr–Nb–B system has been thoroughly investigated with a focus on its macrokinetics and phase formation mechanisms. The activation energies were determined by analyzing the relationship between the combustion rate and temperature. For compositions NbB 2 –40%ZrB 2 and NbB 2 –50%ZrB 2 , the increase in the initial temperature has resulted in a significant change in combustion rate's dependence on temperature, signifying a possible shift in the reaction mechanisms. The quenched combustion front technique (QCF) method in conjunction with thermodynamic and ab initio calculations were used to analyze the sequence of phase formation events, including the formation of niobium and zirconium borides through gas transport reactions involving volatile boron suboxide BO in the heating zone, followed by the emergence of a zirconium-boron melt in the combustion zone and formation of main fraction of niobium and zirconium borides. Interactions between the primary niobium and zirconium borides and the melt result in the formation of solid solutions; however, at sub-optimal combustion conditions multiple non-equilibrium solid solutions are retained in the products. To address this issue, a machine learning model was developed, attaining coefficients of determination (R2) of 89% for combustion temperature and rate predictions, thus enabling the fine-tuning of macrokinetic parameters of the SHS process in the system. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) is an attractive material for gas sensors, and various ZnO-based sensors have been developed to detect gas pollution. In this work, a series of SiC/ZnO composites were fabricated by incorporating silicon carbide nanocrystals (SiC NCs) into ZnO microspheres by a grinding method. The SiC/ZnO composite exhibited a significantly enhanced gas sensitivity response toward NO gas in comparison to ZnO. The test revealed that the response of the composite was 251.1 for 100 ppm of nitrogen monoxide (NO), and the detection limit was as low as 100 ppb. Through spectral and comparative analyses, it has been indicated that the active functional groups of the SiC NCs have a substantial impact on the detection of NO, and the corresponding mechanism is studied and discussed. This work offers a simple strategy for the fabrication of SiC/ZnO material with enhanced sensitivity in sensing applications. [ABSTRACT FROM AUTHOR]

The aim of this investigation was to research physical and mechanical properties a carbonitride zirconium ceramics with addition of nanoparticles zirconium dioxide which were sintered by hot pressing at a temperature of 2000°C, at a pressure of 30 MPa, with an exposure of 15 min. As a result of influence a zirconium dioxide has been achieved an increase a mechanical and physical properties of investigated ceramics. With this addition was achieved a maximum hardness among studied ceramics—2527 HV, observed a decrease in its density and porosity, as well as an increase in the elastic modulus to a value of 767 GPa. At the same time, the value of the critical stress intensity coefficient exceeded 6 MPa m1/2. [ABSTRACT FROM AUTHOR]

High-aspect-ratio ZrB 2 rod crystals were synthesized via a molten-salt-mediated boro/carbothermal reduction using ZrOCl 2 · 8H 2 O/B 4 C/C as the raw material and NaCl as the flux material. This synthesis may improve the poor fracture toughness of monolithic ZrB 2 ceramics. X-ray diffraction and scanning electron microscopy confirmed that the heat-treatment temperature of 1550 °C and the addition of 50 wt% NaCl were the most effective in the preparation of ZrB 2 grains with a high aspect ratio. Thermogravimetric and differential scanning calorimetry was used to study the influence of NaCl addition, which increased the liquid-phase content. Finally, the growth of ZrB 2 grains along the c-axis into rod-like morphology at elevated temperatures was investigated by transmission electron microscopy. This work revealed that the addition of NaCl has a positive effect on the reducing of synthesis temperature and increasing of products particle size. The ZrB 2 rod crystals synthesized have diameters and aspect ratios of approximately 1 μm and 30, respectively. [ABSTRACT FROM AUTHOR]

Novel composite comprising of Kulkual fibers and Titanium diboride (TiB2) filler reinforced epoxy composites is investigated in the current work. Kulkual also known as Opuntia ficus‐indica is a plant abundantly found throughout Ethiopia are utilized in the form fibers in combination with TiB2 as reinforcement to synthesize epoxy matrix composites. Six types of composites including neat epoxy are fabricated using varying content of Kulkual fibers (0, 2.5, 5, 7.5, and 10 vol%) and fixed TiB2 content of 5 vol%. The fibers were obtained by drying the leaf‐like stem of Kulkual and collecting the skeleton structure found in cladodes. Alkaline treatment of Kulkual fiber to study its physical properties was also investigated. All composites' tensile moduli rise with increasing fiber content and are between 21% and 162% higher than the pure epoxy. All the composites tensile strength increase in the range from 43% to 211% compared to neat epoxy with EK‐10 composite revealing the greatest improvement. Flexural properties of all the composites increase with increase in Kulkual fiber content in comparison with neat epoxy. Good bonding of constituents and alkaline treatment of fibers results in enhanced properties of composites. Finally, fractured surfaces are analyzed with scanning electron micrographs to recognize structure property correspondences. [ABSTRACT FROM AUTHOR]

In this study suitability of α-ZrP nanoparticles as a 223Ra and 225Ac carriers for TAT was investigated. The yields of radiolabelling were higher than 98% in both cases. Subsequently, in vitro stability studies were carried out in various biological matrices during 48 h period. Measurements of released radioactivity showed the highest stability in saline. Released activity of 223Ra, 225Ac and their daughter radionuclides was around 0.5%. On the other hand, the lowest stability was shown in plasma and serum. Released activity for 223Ra, 225Ac and their progeny atoms was from 15 to 32%. [ABSTRACT FROM AUTHOR]

The interest for ZrP this material is based on its physicochemical properties which makes this material a perspective candidate for applications in nuclear medicine. In this study ZrP was prepared and completely characterized using various analytical methods. Finally, the study of radiometals sorption mechanism on a surface of ZrP and the surface characterization of ZrP were done. In conclusion, ZrP appears as promising for next studies with various purposes like drug delivery system or ion-exchanger for separations of medical radionuclides such as 225Ac and 213Bi. [ABSTRACT FROM AUTHOR]

A novel adsorbent was prepared through a facile layer-by-layer method and was utilized for the removal of heavy metal ions. Firstly, highly crystalline a-ZrP nanoparticles were synthesized and then exfoliated into single-layer nanosheets. The extremely thin nanosheets were uniformly depos- ited on the surface of cotton through a simple layer-by-layer method with various layers. The resultant adsorbents were applied for the adsorption of Cu2+, Ni2+ and Cd2+ in different conditions and the results showed that the adsorbent performed the best at pH 5 when one layer was deposited. The O-ZrP1@C mixture exhibited the highest adsorption capacities of all, with 83.75mg/g for Cu2+, 29.16mg/g for Ni2+ and 55.66mg/g for Cd2+. The results showed that the experimental data were fitted in pseudo-second-order kinetic model and Langmuir isotherm model. The results indicated that the ZrP-cotton mixture would be a promising candidate for practical application in the treatment of wastewater contaminated with heavy metal ions. [ABSTRACT FROM AUTHOR]

The ferroelectric, ferroelastic, and dielectric properties as well as the crystal structure were investigated for polycrystalline donor doped lead zirconate titanate (PZT) with grain sizes ranging from 0.25 to 5 μm, which were prepared using a novel zirconium titanium hydrate precursor (ZTH) with a specific surface area of 310 m2/g. Piezoforce microscopy was used to investigate the change in the domain structure, revealing a change in the domain configuration from a complex 3D structure to a simple lamellar domain formation at a 1 μm grain size that corresponded to a rapidly increasing internal mechanical stress observed with in situ synchrotron x-ray experiments. The correlation between the change in domain configuration, increasing internal stresses, effects of poling on the crystal structure, and the macroscopic ferroelectric and ferroelastic properties are discussed in detail, allowing a deeper understanding of size effects in polycrystalline donor doped PZT ceramics. [ABSTRACT FROM AUTHOR]

The pressure-induced phase transition and mechanical properties of rhenium diboride (ReB2) have been investigated by using the particle swarm optimization algorithm in combination with density functional theory calculations. It was found that the P63/mmc structure of ReB2 (hP6-ReB2) is the most stable phase at ambient conditions, and it will transform to P6/mmm structure (hP3-ReB2) at about 300.7 GPa. Phonon dispersion curve calculations suggest that hP6-ReB2 and hP3-ReB2 possess dynamical stabilities in a wide range of 0–400 and 120–400 GPa, respectively. Moreover, the calculated hardness of hP6-ReB2 is 38.1 GPa at ambient conditions, suggesting it is a potential hard material. However, hP3-ReB2 just possesses the hardness value of 18.9 GPa at the pressure of 120 GPa. Finally, by means of the quasiharmonic approximation method, the high-pressure and finite-temperature phase diagram of ReB2 is proposed. It is found that the transition pressure of hP6-ReB2 to hP3-ReB2 decreases with increasing temperatures. [ABSTRACT FROM AUTHOR]

Different amounts of sodium-alendronate (ALN) were loaded into layered zirconium phosphates of alpha and gamma type (αZP and γZP) by means of topotactic exchange reactions of phosphate with ALN. In order to extend the exchange process to the less accessible interlayer regions, ALN solutions were contacted with colloidal dispersions of the layered solids previously exfoliated in single sheets by means of intercalation reaction of propylamine (for αZP) or acetone (for γZP). The ALN loading degree was determined by liquid P-nuclear magnetic resonance (NMR) and inductively coupled plasma (ICP), and it was reported as ALN/Zr molar ratios (Rs). The maximum R obtained for γZP was 0.34, while αZP was able to load a higher amount of ALN, reaching Rs equal to 1. The synthesized compounds were characterized by X-ray powder diffractometry, scanning electron microscopy (SEM), solid-state NMR, and infrared spectroscopy. The way the grafted organo-phosphonate groups were bonded to the layers of the host structure was suggested. The effect of ZP derivatives was assessed on cell proliferation, and the results showed that after 7 days of incubation, none of the samples showed a decrease in cell proliferation. [ABSTRACT FROM AUTHOR]

Zr–B–Si–C–Ti and Zr–B–Si–C–Ti–N coatings have been produced for the first time by an arc physical vapor deposition process in a residual argon + nitrogen atmosphere. The Zr–B–Si–C–Ti coating had an amorphous–nanocrystalline structure. Nanocrystallites were formed in the Ti–B–C system, and the amorphous component of the material was formed by Zr–B–C and Si–C phases. The coating of the latter system had a predominantly amorphous structure (amorphous content of ~85–93%) based on titanium nitride with Ti–B and Ti–C bonds, zirconium carboboronitride (Zrx(C,N,B)y), zirconium boride, and silicon carbonitride. [ABSTRACT FROM AUTHOR]

Zirconium phosphate (α‐ZrP) was modified by o‐phenylenediamine (OPD) grafting to its surface, named ZPD, and used to improve thermal‐oxidative stability of nitrile butadiene rubber (NBR) by direct blending method. The results of Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), X‐ray diffraction, and contact angle test, demonstrated that OPD was grafted to the surface of α‐ZrP successfully. Scanning electron microscopy results showed that OPD could effectively improve the interaction between α‐ZrP and NBR and a better the dispersion of α‐ZrP in the rubber matrix. The fracture strength of the NBR composites was increased by 3.3 Mpa with the addition of 3 phr ZPD fillers, respectively, compared with unmodified NBR/α‐ZrP composites. In addition, TGA, DMA, and FWO analysis showed ZPD fillers, combined lamellar barrier of α‐ZrP with radical trapping ability of OPD, could retard oxidative cross‐linking and fracture reaction of rubber chains, and improve the thermal‐oxidative aging resistance of the NBR composites. This work provides a practical and effective methodology for surface modification of α‐ZrP and preparation of high‐performance NBR composites. [ABSTRACT FROM AUTHOR]

The impact of wear factors on composite materials is examined in this article. Stir casting was used to produce AA7075 alloys with varied nano-zirconium boride weight ratios. The dry sliding wear test was done utilizing pin-on-disc test equipment. The L27 orthogonal array was built by Taguchi's experiments for optimization. We calculated the proportion of responses that could be attributed to the input parameters using SNR and ANOVA. The rate of wear and the frictional coefficient raised with the highest loading level. Load concentration had an extreme impact on wear rate, coefficient of friction, sliding distance, and speed. Nano-zirconium boride particles placed in the matrix alloy prohibited any material loss. Zirconium boride nanoparticles were applied to AA7075 to increase its wear resistance. [ABSTRACT FROM AUTHOR]

[Display omitted] To improve the selectivity of cation-exchange membranes to the transfer of lithium with respect to magnesium during the electrodialysis desalination of lithium and magnesium sulfates solutions, the surface of a commercial cation-exchange membrane based on sulfated polystyrene was modified with cerium(III, IV) and zirconium phosphates. Upon incorporation of phosphate particles, the Li/Mg selectivity coefficients of the membranes increased up to 113%. [ABSTRACT FROM AUTHOR]

ZrB 2 -MeC and ZrB 2 -19 vol% SiC-Me x C y where Me=Cr, Mo, W were obtained by pressureless sintering. The capability to promote densification of ZrB 2 and ZrB 2 -SiC matrices is the highest for WC and lowest for Cr 3 C 2. The interaction between the components results in the formation of new phases, such as MeB (MoB, CrB, WB), a solid solution based on ZrC, and a solid solution based on ZrB 2. The addition of Cr 3 C 2 decreases the mechanical properties. On the other hand, the addition of Mo 2 C or WC to ZrB 2 -19 vol% SiC composite ceramics leads increased mechanical properties. Long-term oxidation of ceramics at 1500 °C for 50 h showed that, in binary ZrB 2 -Me x C y , a protective oxide scale does not form on the surface thus leading to the destruction of the composite. On the contrary, triple composites showed high oxidation resistance, due to the formation of dense oxide scale on the surface, with ZrB 2 -SiC-Mo 2 C displaying the best performance. • The capability to promote the densification of zirconium boride increases in the order WC>Mo2C>Cr3C2. • The hardness, and strength of ceramics based on zirconium diboride varying in the ~14 – ~19 GPa, and ~196 – 375 MPa range. • The ZrB 2 -SiC-Mo 2 C (WC) ceramics obtained by pressureless sintering have excellent long-term oxidation resistance at 1500 °C. [ABSTRACT FROM AUTHOR]

In order to obtain a steam-stable hydrogen permselectivity membrane, with tetraethylorthosilicate (TEOS) as the silicon source, zirconium nitrate pentahydrate (Zr(NO3)4·5H2O) as the zirconium source, and methyltriethoxysilane (MTES) as the hydrophobic modifier, the methyl-modified ZrO2-SiO2 (ZrO2-MSiO2) membranes were prepared via the sol-gel method. The microstructure and gas permeance of the ZrO2-MSiO2 membranes were studied. The physical-chemical properties of the membranes were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), and N2 adsorption–desorption analysis. The hydrogen permselectivity of ZrO2-MSiO2 membranes was evaluated with Zr content, temperature, pressure difference, drying control chemical additive (glycerol) content, and hydrothermal stability as the inferred factors. XRD and pore structure analysis revealed that, as nZr increased, the MSiO2 peak gradually shifted to a higher 2θ value, and the intensity gradually decreased. The study found that the permeation mechanism of H2 and other gases is mainly based on the activation–diffusion mechanism. The separation of H2 is facilitated by an increase in temperature. The ZrO2-MSiO2 membrane with nZr = 0.15 has a better pore structure and a suitable ratio of micropores to mesopores, which improved the gas permselectivities. At 200 °C, the H2 permeance of MSiO2 and ZrO2-MSiO2 membranes was 3.66 × 10−6 and 6.46 × 10−6 mol·m−2·s−1·Pa−1, respectively. Compared with the MSiO2 membrane, the H2/CO2 and H2/N2 permselectivities of the ZrO2-MSiO2 membrane were improved by 79.18% and 26.75%, respectively. The added amount of glycerol as the drying control chemical additive increased from 20% to 30%, the permeance of H2 decreased by 11.55%, and the permselectivities of H2/CO2 and H2/N2 rose by 2.14% and 0.28%, respectively. The final results demonstrate that the ZrO2-MSiO2 membrane possesses excellent hydrothermal stability and regeneration capability. [ABSTRACT FROM AUTHOR]

Zirconium diboride (ZrB2) is a typical ultra-high temperature ceramic material (UHTC). In this work, the preparation of ZrB2 by reducing zirconia (ZrO2) with calcium hexaboride (CaB6) was studied in detail. With the assistance of molten salt, the reduction rate was dramatically enhanced. Additionally, the results showed that ZrB2 products with different particle shapes were prepared by changing the type of molten salt (NaCl, KCl, MgCl2, and CaCl2). However, the particle size of products could not be properly refined when nano-ZrO2 was used as the raw material. During the process of reducing ZrO2 by CaB6, B2O3 could be formed, which would cause the loss of B source. To decrease the consumption of CaB6, Ca-assisted reduction was performed, and monophase ZrB2 was obtained. The varied morphologies of ZrB2 particles obtained by Ca-assisted reduction were the result of complex reaction mechanisms. [ABSTRACT FROM AUTHOR]

[Display omitted] • Branched diluents have a good inhibition effect on Zr-DBP precipitation formation. • The P–OH and P=O on one HDBP can bridge two Zr-DBP complexes into a stable dimer. • Interactions between diluent-diluent molecules play a crucial role for precipitation. • Straight-chain n-dodecanes have a strong intermolecular force than branched diluents. • There is larger diluent-complex interaction in branched alkanes than in n-dodecanes. In solvent extraction processes, there are challenges caused by the formation of the third phase or interfacial precipitation. The branched alkanes have been used as diluents to disrupt the third-phase formation, while there is little study about the effect of diluents on the appearance of precipitation. Here, we report the inhibiting effect of the novel hyperbranched alkane diluent (HAD) on the formation of zirconium-dibutyl phosphate (Zr-DBP) precipitation and investigate the formation mechanism by the density functional theory (DFT) theory. The extraction experiments show that HAD as the diluent has a remarkable inhibiting ability to form Zr-DBP precipitation, compared with n-dodecane and kerosene. The spectra show no noticeable difference in the composition and structures of the precipitations formed in the three diluents. The energetics from the DFT calculations suggest the P-OH and P=O ligands on one HDBP molecule can bridge two Zr-DBP complexes into a dimer and then aggregate into the precipitation. Besides, the interactions between diluent-diluent molecules play a significant role in precipitation formation. The straight-chain n-dodecanes have a strong intermolecular dispersion force and tend to attract each other but not the Zr-DBP complex. However, the branched alkanes with weak intermolecular interactions have a better dispersive capacity for Zr-DBP complexes, due to the much higher dispersion force of diluent-complex interaction than that of the diluent-diluent interaction. This work provides a new insight into the formation of interfacial crud from the interactions between solutes and diluents of the organic phase in solvent extraction. [ABSTRACT FROM AUTHOR]

[Display omitted] • The lattice parameters of ZnO are modified through introduction Mn2+. • Mn2+ doped ZnO promotes the formation of V O • and inhibits the growth of Zn i. • Mn2+ doped ZnO enhances electrical conductivity by narrowing the band gap. • Regulation of intrinsic point defects can improve the electrical characteristic. Transition metal doping is considered one of the most effective approaches for enhancing the electrical properties of ZnO. The performance of ZnO is primarily influenced by intrinsic point defects present in the depletion layer. In this study, we employ first principles calculations to investigate the variation of intrinsic point defects impact of ZnO and Mn2+ substitution doped ZnO. Our findings reveal that Mn2+ substitution significantly improves the conductivity of ZnO by narrowing the band gap. Mn2+ substitution lattice Zn inhibits zinc interstitial formation and promotes oxygen vacancy growth via increasing zinc interstitial formation energy and decreasing oxygen vacancy formation energy. Simultaneously, Mn2+ can cause changes in ZnO crystal lattice. [ABSTRACT FROM AUTHOR]

The present paper focusses on the effect of cationic migration in the sintered CoFe 2 O 4 /ZnO composite. The increase in lattice parameter of the CoFe 2 O 4 after sintering indicates substitution of Zn. Mӧssbauer analysis of the samples indicates the transformation of composites to paramagnet in the sample sintered at 600 and 750 °C. At 900 °C, a low hyperfine field sextet was evolved complimented by MH loop which is due to redistribution of cations and formation of ferromagnetic phase. Maxwell-Wagner dispersion was identified by the frequency-dependent fluctuation of dielectric constants (ε׳) and dielectric loss (tan δ). Dielectric constant values of 8.66, 7.90, 9.31 and dielectric loss value of 0.11, 0.03, 0.05 were found for CZ6, CZ7 and CZ9 respectively at 1 MHz frequencies. The composite are suitable for high frequency applications due to its low loss, high resistance, low sintering temperature. The mechanisms behind these observations are discussed in this paper. [ABSTRACT FROM AUTHOR]

TG/FT-IR techniques, UV-spectroscopy, microwave extraction, XRD and SEM were used to study how densification of the three types of agricultural biomass wastes (wheat straw, soft wood, and sunflower husk) changes the composition and structure of their pyrolysis products. It was determined that densification changes the composition of volatile products of pyrolysis at the temperature of 420 °C: sunflower husk emits 4.9 times less saturated and unsaturated hydrocarbons and 1.9 times less compounds with carbonyl group; soft wood emits 1.8 times more saturated and unsaturated hydrocarbons and compounds with carbonyl groups and 1.3 times more alcohols and phenols; and wheat straw emits 2 times more compounds with carbonyl groups. These changes are probably caused by the differences in interaction of formed volatiles with the surface of chars. These differences can be caused by distinct places of cumulation of inorganic components in the densified samples. In the densified char, the inorganics cumulate on the surface of sunflower husk whereas for wheat straw they cumulate inside the sample. In the case of soft wood, the inorganics cumulate both inside and on the surface. The decreased contribution of hydrocarbons in volatiles can be connected with the morphology of nano-particles formed in inorganics. [ABSTRACT FROM AUTHOR]

The residual strength of composite ceramic materials based on zirconium boride constitutes more than 50% of their initial strength after oxidation at a temperature of 1500°C with holding for 50 h or at a temperature of 1600°C with holding for 2 h. It is shown that the process of softening of the ceramics is caused by heterogeneities formed in the scale in the form of delaminations of individual zirconium-dioxide grains or groups of these grains from the base, especially in the ZrB2–15% SiC system. As a result of the addition of Mo2C, WC, and W2B5, the residual strength increases due to the formation of denser and thinner oxidized layers. However, due to the presence of pores and cracks, this level of strength cannot be preserved. At the same time, the initial level of strength can be preserved in the ZrB2–15% MoSi2 system characterized by the formation of a dense scale and fine zirconium-oxide grains in the process of oxidation. The residual strength is affected by the structure of the scale, the thickness and size of inclusions inside it, and internal stresses. [ABSTRACT FROM AUTHOR]

In this study, the effects of heat transfer and heat flux on cutting tools with materials of Al2O3, ZrB2, TiB2, TiN are investigated numerically by ANSYS fluent software. The numerical model was validated with the previous study. The influence of the machining parameters such as cutting speed and feed rate on the temperature and tool life has been investigated to indicate the optimum cutting tool and situation. The results show that Zirconium diboride (ZrB2) and Titanium diboride (TiB2) have a temperature less than the aluminum oxide (Al2O3) so that the productivity will increase with the diboride materials utilizing as cutting tool. The maximum temperature for aluminum oxide is 1300 K while the Titanium Nitrite achieved 1100 K. The lowest and maximum temperature was measured at a cutting speed of 180 m/min and 220 m/min, respectively. The optimum cutting condition has been obtained with TiN cutting tool material at 180 m/min cutting speed and 0.138 mm/rev feed rate. Titanium diboride (TiB2) materials achieved the maximum cutting tool life comparing to other materials. [ABSTRACT FROM AUTHOR]