Solid Powder Research Articles

CaFe2O4@SiO2-Cu as a novel and highly efficient nanocatalyst for direct conversion of epoxides to β-acetoxy esters

Direct conversion of structurally various epoxides to the related β-acetoxy esters was investigated using catalytic amounts of CaFe2O4@SiO2-Cu. The reactions were accomplished in the presence of acetic anhydride under solvent-free conditions within 0.5–2 h to give desired products in high yields. Initially, the CaFe2O4 nanoparticles were manufactured through a chemical coprecipitation reaction of calcium nitrate and hydrated iron (III) nitrate in the presence of ammonium hydroxide solution, and then calcined at 800 ºC. Next, to protect the prepared CaFe2O4 from oxidation and aggregation, its surface was covered with a silica layer to give CaFe2O4@SiO2. Eventually, by adding copper chloride solution followed by potassium borohydride solid powder, Cu nanoparticles were successfully immobilized on the silica surface and the new CaFe2O4@SiO2-Cu nanocomposite was obtained. FT-IR, SEM, EDX, VSM, ICP-OES, TGA, TEM and XRD techniques were employed to characterize the newly synthesized nanostructure. In addition, durability of the catalyst was considered for several sequential reaction cycles without the notable loss of catalytic activity. The absence of hazardous organic solvents, high product yields, short reaction times and recoverability of the magnetic catalyst are among the remarkable advantages of the introduced procedure.

Microsphere as a Novel Drug Delivery System : A Review

Microspheres play a very important role as particulate drug delivery system because of their small size and other efficient properties. Microspheres have been proved to be a suitable bridge to scale the distance over to formulate an effective dosage form, to simulate controlled drug release. Microspheres are characteristically free flowing solid powders, which consist of proteins or synthetic polymer, which are biodegradable in nature[1]. Microsphere size ranges Between 1 to 1000 um . It can be administered By oral, Parentral ,Transdermal, ophthalmic, nasal ,colonal routes etc. Microspheres received much attention not only for prolonged release, but also for targeting of anticancer drugs. In future by combining various other strategies, microspheres will find the central place in novel drug delivery, particularly in diseased cell sorting, diagnostics, gene & genetic materials, safe, targeted and effective in vivo delivery and supplements as miniature versions of diseased organ and tissues in the body[2]

Pengaruh Celebrity Endorser dan Brand Trust terhadap Minat Beli Ulang pada Produk Bedak Padat Wardah di Kota Cimahi

The purpose of the study was to test and determine the influence of Celebrity Endorser and Brand Trust on the interest to buy again for users of Wardah compact powder products. The approach applied is a quantitative method through the use of primary data obtained from questionnaires. The number of samples in this study there are 90 respondents through the use of technical purposive sampling, then the data were analyzed using SPSS data processing version 25. The specified population is consumers who have previously used solid powder products from Wardah domiciled in Cimahi. The resulting research shows that celebrity endorser can influence the repurchase interest positively, brand trust can affect the repurchase interest positively, simultaneously celebrity endorser and brand trust can affect the repurchase interest.

Sublimation rate of solid NaCl powders and evaporation rate of liquid NaCl upon heating in vacuum and air

The volatilization of sodium chloride (NaCl) is important for multiple applications, such as energy storage, manufacturing porous parts, and purification and recycling of composites. Until now, only limited information on this feature has been published. To expand the knowledge in this field, we investigated the sublimation and evaporation of two NaCl powders by thermal gravimetry in vacuum and air. The study has shown that the volatilization kinetics of powders with different shapes and sizes are identical. The volatilization of NaCl powders in vacuum occurs mainly by sublimation before melting. In contrast, the volatilization of NaCl in the air is preferentially caused by the evaporation of the melt. In a vacuum, the evaporation of NaCl powder after melting is significantly slower than the sublimation before melting, because of a drastic decrease in the volatilization area. The Hertz-Knudsen relation with an appropriate fitting coefficient satisfactorily describes the mass loss by volatilization in vacuum and air.

Evaluation on Preparation and Performance of a Low-Carbon Alkali-Activated Recycled Concrete under Different Cementitious Material Systems.

A green, low-carbon concrete is a top way to recycle waste in construction. This study uses industrial solid waste slag powder (S95) and fly ash (FA) as binders to completely replace cement. This study used recycled coarse aggregate (RCA) instead of natural coarse aggregate (NCA). This is to prepare alkali-activated recycled concrete (AARC) with different cementitious material systems. Alkali-activated concrete (AAC) mixtures are modified for strength and performance based on the mechanical qualities and durability of AARC. Also, the time-varying effects of the environment on AARC properties are explored. The results show that with the performance enhancement of RCA, the mechanical performance of AARC is significantly improved. As RCA's quality improves, so does AARC's compressive strength. At a cementitious material content of 550 kg/m3, AARC's 28d compressive strengths using I-, II-, and III-class RCA were reduced by 2.2%, 12.7%, and 21.8%, respectively. I-class AARC has characteristics similar to natural aggregate concrete (NAC) in terms of shrinkage, resistance to chloride penetration, carbonization, and frost resistance. AARC is a new type of green building material that uses industrial solid waste to prepare alkali-activated cementitious materials. It can effectively reduce the amount of cement and alleviate energy consumption. This is conducive to the reuse of resources, environmental protection, and sustainable development.

Study on thermoelectric properties and atomic-scale mechanism of B-site molybdenum-modified La0.1Sr0.9TiO3

Extensive studies on strontium titanate thermoelectric materials have shown that their poor conductivity results in a low ZT value. However, elemental doping can effectively improve the thermoelectric properties of these materials. In this study, a two-step sintering process was applied, using physical mixing to introduce 1 % molybdenum powder as a modification to the lanthanum-doped strontium titanate solid powder (La0.1Sr0.9TiO3). The obtained sample exhibited a maximum conductivity of 7830 S/m, with a maximum ZT of 0.12. Furthermore, this study combined experimental data with first-principles simulation calculations to elucidate the mechanism at the atomic scale. The incorporation of Mo6+ in place of Ti4+ at the B-site by molybdenum (Mo) adds two free electrons, leading to an elevated carrier concentration. This change concurrently reduces the Fermi level of the material and improves mobility, collectively resulting in a substantial increase in electrical conductivity. Phonon simulation indicated that Mo doping increased structural defects, thereby reducing lattice thermal conductivity. This significant enhancement in electrical conductivity and decrease in lattice thermal conductivity collectively increased the ZT value of the material.

Evaluation and comparison for higher temperature performance index of emulsified asphalt mastic using coal gangue powder

In order to investigate the rheological behavior and the influence of solid waste coal gangue powder on the high-temperature performance of cold recycled Emulsified Asphalt Mastics (EAM), Dynamic Shear Rheometer (DSR) and Multiple Stress Creep Recovery (MSCR) tests were conducted using three different fillers and four powder-to-binder ratios of EAM. Evaluation indexes such as rutting factor (G*/sinδ), improved rutting factor (G*/1−1/sinδ∙tanδ), Unrecoverable Creep Compliance (Jnr), Cumulative Strain (CS) and Creep Recovery Ratio (R) were used to analyze the influence of filler type and dosage on high temperature of EAM, and the effectiveness of these indexes to evaluate high temperature is considered. Moreover, atomic force microscopy experiments were carried out to study on interaction mechanism between the fillers and emulsified asphalt. Finally, grey relational analysis method was used for quantitative assessment of these indexes for EAM. The results indicate that all three fillers effectively improve the high-temperature performance, with a larger improvement observed as the filler dosage increases, among which the tunneling coal gangue powder is the most significant. Under a stress level of 0.1 KPa, the coal gangue filler mastic appears the best deformation recovery ability, whereas under a stress level of 3.2 KPa, the cement filler mastics appears the best deformation recovery ability. The additional fillers significantly influence the nano-scale surface morphology of the residues, and the tunneling coal gangue powder appears a stronger adsorption capacity for free polar components compared to the cement and limestone mineral powder. It is suggested that the Jnr and CS can be used as evaluation indexes of high temperature evaluation index of EAM, instead of G*/1−1/sinδ∙tanδ or G*/sinδ or R.

Synthesis and oxidation behavior of Ti-Zr-Ta(Hf) high entropy carbide nanopowders by sol-gel method

Multi-component solid solution carbide is a promising material due to its excellent mechanical strength, thermal stability, and resistance to chemical corrosion. In this study, we intentionally designed and synthesized three types of solid solution carbide powders using the sol-gel method: (Ti1/3Zr1/3Ta1/3)C, (Ti1/3Zr1/3Hf1/3)C and (Ti1/4Zr1/4Ta1/4Hf1/4)C. The results show that the liquid-phase precursor undergoes pyrolysis at 800 °C and subsequently form homogeneous single face-centered cubic structure solid solutions upon thermal treatment at temperatures exceeding 1800 °C. The obtained powders exhibited ultra-fine and uniform particle sizes of 340 nm, 248 nm, and 401 nm, respectively. Furthermore, the oxidation behavior of the three types of carbide powders in air shows that Hf and Ta elements are of great significance in improving oxidation resistance. The solid solution of Hf increases the initial oxidation temperature, while Ta tends to form a complex oxide with Zr, which helps to improve the oxidation temperature resistance. This work therefore contributes filling the gap of employing the sol-gel method in the fabrication of multi-component solid solution carbide materials and provides novel insights into their synthesis mechanism and oxidation behaviours.

Studying the Effect of Composition on the Crystal Structure, Optical Properties, and Photogenerated Current Carriers Lifetimes in AgxCu1 – xGaSe2 (0 ≤ x ≤ 1) Solid Solutions

A set of AgxCu1 – xGaSe2 (0 ≤ x ≤ 1) solid solution powders has been prepared by solid-state synthesis. Using a combination of X-ray diffraction analysis and Raman spectroscopy, it has been found that the samples have a single-phase tetragonal structure (space group I-42d). It has been shown that their crystal lattice parameters do not follow Vegard’s law up to x ≈ 0.4. It has been revealed that the band gap of the samples also changes nonlinearly: initially it decreases and then increases. Studies of the low-temperature luminescence and microwave photoconductivity decay spectra have shown that a set of samples with x of 0 to ~0.4 and further in the region with x > 0.4 is characterized by an increase in the photogenerated current carrier lifetime in AgxCu1 – xGaSe2 powders. The observed effect is apparently attributed to the replacement of deep charge carrier traps, such as selenium vacancies, by shallower cation vacancies.

Sodium Triphosphate Effect on Encapsulation of Vitamin B<sub>6</sub> into Chitosan-Alginate Nanoparticles and Its <i>In Vitro</i> Drug Release Study

The in-vitro drug release study of vitamin B6 encapsulated into sodium tripolyphosphate crosslinked chitosan-alginate (B6-TCA) nanoparticles aims to determine the effect of sodium tripolyphosphate on the encapsulation efficiency of vitamin B6 and effectiveness of the nanoparticles to release vitamin B6. The focus of this research is synthesizing and characterizing TCA nanoparticles to encapsulate vitamin B6 as an effective delivery system by studying the kinetics release of vitamin B6. The research resulted in the formation of coarse solid powder nanoparticles in yellowish-white color with a nanoparticle size of 22.55 nm. Sodium tripolyphosphate decreased the percentage of encapsulation efficiency in the B6-TCA nanoparticles as its concentration increased. However, the increasing sodium tripolyphosphate causes a slower release of vitamin B6 from nanoparticles. The encapsulation efficiency of vitamin B6 is 82.04%. The optimum composition of B6-TCA nanoparticles ratio is 2:1:1.5:2, where Korsmeyer-Peppas kinetics model suited its better with the Fickian diffusion mechanism of 0.989 and has the smallest reaction rate constant of 0.039 occurred within 6 h.

Production and Characterization of Porous Anorthite Ceramics Using Sugar Process Solid Waste, Chamotte and Coal Powder Additives

Press filter cake is a solid waste produced during sugar production process and includes carbonates and organic components. In this study, coal powder in different percentages (from 10 wt.% to 50 wt.%) was mixed with 35 wt.% press filter cake and 65 wt.% chamotte composition to produce porous anorthite ceramic products with different apparent porosity percentages. The anorthite phase was observed as the dominant crystalline phase in all fired samples. The firing shrinkage values sharply increased after adding higher than 40 wt.% coal powder to composition. In addition, apparent porosity values were changed from 49% to 70%. Compressive strength values reduced from 18 MPa to 1.73 MPa while percentages of ground coal were increasing. Microstructural analysis also showed that the porosity values of the sintered samples showed important changes depending on the amount of coal additive. The thermal conductivity values showed a reduction from 0.113 W/mK to 0.064 W/mK while increasing the percentage of ground coal. Micro-computed tomography (Micro CT) analysis was performed for 40wt. % coal powder added composition and the total porosity value was found as 60.2%.

Hydrophobic cement: Concept, preparation and application

Integral hydrophobic cement-based materials (CBMs) have traditionally been built by adding hydrophobic liquid solvents, hydrophobic solid powders, or admixtures modified by hydrophobic agents. In this work, we propose a new strategy to construct an integral hydrophobic CBMs based on direct hydrophobic cement. By ball milling, the 1.0 wt% stearic acid (SA) is adopted as modifier to prepare hydrophobic cement (SA1.0). SA1.0 process provides better dispersity in making CBMs. Hence, by using SA1.0 process, the CMB mechanical properties and durability can be improved. The mechanical and working performance of SA1.0 meet P·O 42.5 grade. Freeze-thaw resistance, sulfate resistance and electrochemical tests have demonstrated that CBMs prepared via SA1.0 process own excellent durability. Our findings provide new strategies for the formation of integral hydrophobic CBMs and a novel hydrophobic cementitious material for long-life CBMs.

Effect of Pr6O11 addition on the electrical properties of Sm0.2Ce0.8O1.9 electrolyte materials for solid oxide fuel cells

Sm[Formula: see text]Ce[Formula: see text]O[Formula: see text] (SDC) solid electrolyte powder for solid oxide fuel cells was prepared by sol-gel method, and Pr6O[Formula: see text] was added to improve the electrochemical performance. The effect of Pr6O[Formula: see text] addition on the electrical properties was studied. X-ray diffraction (XRD) analyses confirmed that the structure of SDC and Pr6O[Formula: see text] does not change, the two materials still maintain their original structure in Pr6O[Formula: see text]-Sm[Formula: see text]Ce[Formula: see text]O[Formula: see text] composite. Scanning electron microscopy (SEM) results showed that the Pr6O[Formula: see text]-Sm[Formula: see text]Ce[Formula: see text]O[Formula: see text] composite exhibits superior sintering activity and can form a dense ceramic structure after sintering at 1250∘C. The electrochemical performance of the electrolyte was tested in air using AC impedance technique in the temperature range of 500–650∘C. The results showed that the conductivity of Sm[Formula: see text]Ce[Formula: see text]O[Formula: see text] can significantly increase by adding the right amount of Pr6O[Formula: see text], and the highest conductivity of 0.053 S/cm can be seen in the 15% Pr-SDC sample at 650∘C. In conclusion, the Pr6O[Formula: see text]/Sm[Formula: see text]Ce[Formula: see text]O[Formula: see text] composite electrolyte shows a promising prospect as an electrolyte material for medium or low-temperature solid oxide fuel cells due to its excellent electrical properties.

Preparation of uranium-plutonium oxide solid solution powder from ammonium uranyl-plutonyl carbonate in a laboratory microwave unit

The method of obtaining a solid solution powder of uranium-plutonium oxides (with 38% plutonium content) from the AUPuC pulp of the process (ammonium uranyl-plutonyl carbonate) using microwave radiation in reducing and atmospheric environments was proposed and tested at the laboratory level. For research purposes, the pulp obtained by coprecipitation of uranium and plutonium from nitrate solution (stripping product simulator) was prepared in advance. The process consists of three main stages: oxidation of Pu(IV) to Pu(VI), precipitation, and conversion in a laboratory microwave unit. According to the X-ray phase analysis, the powder obtained in a reducing atmosphere is a solid cubic solution (UxPu1–x)O2. The powder obtained in an atmospheric environment is a mixture of two oxides, PuO2 and U3O8. Scanning electron microscopy and electron probe microanalysis of the powder obtained in an atmospheric environment showed a fairly uniform distribution of U, Pu, and O in the solid phase.

Star-shaped multifunctional organic emitters based on N-(2-cyanophenyl) carbazole frameworks: Effects of steric hindrance fluorene and heavy-atom bromine

To investigate the effects of steric hindrance fluorene and heavy-atom bromine on the general optoelectronic properties of star-shaped organic emitters based on 9-(2-cyanophenyl) carbazole (OCzPhCN) frameworks, heavy element of bromine and steric hindrance fluorene were introduced into OCzPhCN to produce four derivatives of 2-(3-bromo-9H-carbazol-9-yl)benzonitrile (BrCzPhCN), 2-(3-bromo-6-(9-(4-ethoxyphenyl)-9H-fluoren-9-yl)-9H-carbazol-9-yl)benzonitrile (BrFCzPhCN), 2-(3-(9-(4-ethoxyphenyl)-9H-fluoren-9-yl)-9H-carbazol-9-yl)benzonitrile (FCzPhCN) and 2-(3,6-bis(9-(4-ethoxyphenyl)-9H-fluoren-9-yl)-9H-carbazol-9-yl)benzonitrile (2FCzPhCN). The fluorene units obviously improve the thermal stability of the obtained compounds, and 2FCzPhCN has the highest thermal stability with 5 % mass heat loss temperature reaching 447 °C. In different polar solvents, the absorption peaks wavelength of OCzPhCN, FCzPhCN and 2FCzPhCN are basically unchanged, and the redshifted emission peaks are positively correlated with solvent polarity. The photoluminescence quantum yields (PLQYs) of OCzPhCN, BrCzPhCN, FCzPhCN, BrFCzPhCN and 2FCzPhCN powders were 20.17 %, 5.43 %, 30.75 %, 3.27 % and 23.56 %. The fluorescence and phosphorescent quantum efficiencies of OCzPhCN, BrCzPhCN, FCzPhCN, BrFCzPhCN and 2FCzPhCN powders are 9.76 % and 10.41 %, 1.2 % and 3.23 %, 28.45 % and 2.3 %, 3.27 % and 0 %, 23.56 % and 0 %. OCzPhCN, BrCzPhCN and FCzPhCN powders show obvious room temperature phosphorescent emission, and the phosphorescent emission lifetime of OCzPhCN, BrCzPhCN and FCzPhCN powders at 561 nm, 576 nm and 568 nm are 193.17 ms, 18.65 ms and 7.25 ms. Compared with OCzPhCN, the introduction of bromine decreases the PLQY and the phosphorescent lifetime of BrCzPhCN powder, while the fluorescence quantum efficiency of the compound FCzPhCN powder has been improved. The corresponding single-triplet energy splitting (ΔEST) of OCzPhCN, FCzPhCN and 2FCzPhCN in solutions are 0.49 eV, 0.63 eV and 0.63 eV, and the corresponding ΔEST values of OCzPhCN, BrCzPhCN FCzPhCN powders are 1.19 eV, 0.74 eV and 0.55 eV. The steric hindrance fluorene units result in smaller and stabilized ΔEST in the solid powder states, and the same situation is opposite in the unimolecular solutions. The maximum external quantum efficiency of organic light-emitting diode based on 10,10′-(4,4′-sulfonylbis (4,1-phenylene)) bis (9,9-dimethyl-9,10-dihydroacridine) hosted by OCzPhCN reaches 12.7 %, and the external quantum efficiency at 100 cd/m2 rolls down to 11 %. OCzPhCN is the best emitters in terms of room temperature phosphorescent emission and host applications.

Glucose-Responsive Microneedle Patch with High Insulin Loading Capacity for Prolonged Glycemic Control in Mice and Minipigs.

Transdermal microneedle-mediated glucose-responsive insulin delivery systems can modulate insulin release based on fluctuations in blood glucose levels, thus maintaining normoglycemia effectively in a continuous, convenient, and minimally invasive manner. However, conventional microneedles are limited by the low drug loading capacity, making it challenging to be applied on human skin at a reasonable size for a lasting glucose-controlling effect, thus hindering their clinical translation. Here, we design a microneedle patch with a solid insulin powder core to achieve a high loading capacity of insulin (>70 wt %) as well as a glucose-sensitive polymeric shell to realize glucose-responsive insulin release. Once exposed to hyperglycemia, the formation of negatively charged glucose-boronate complexes increases the charge density of the shell matrix, leading to swelling of the shell and accelerating insulin release from the core. We have demonstrated that this glucose-responsive microneedle patch could achieve long-term regulation of blood glucose levels in both type 1 diabetic mice and minipigs (up to 48 h with patches of ∼3.5 cm2 for minipigs >25 kg).

3D inkjet printing of hybrid electroactive ink based on molecularly imprinted polymers for lipopolysaccharides detection

A hybrid electroactive ink based on molecularly imprinted polymer (MIP) hollow microparticles, zinc oxide nanoparticles (ZnO NPs) and conductive carbon paste (CP) is reported herein for the first time. The MIP/ZnO NPs/CP and corresponding non-imprinted NIP/ZnONPs/CP modified inks were screen-printed on plastic substrates via 3D inkjet technology to cover around 40 working screen-printed carbon electrodes (SPCE) pieces in a single batch. The custom-made electrochemical MIP/ZnONPs/CP@SPCE sensor was designed for the detection of bacterial endotoxins, i.e., lipopolysaccharides (LPS), derived from Pseudomonas aeruginosa. Hollow MIP silica microparticles with specific properties for 3D printing application, in terms of granulation and morphology, were synthesized via sol-gel method using tetraethyl orthosilicate and (3-aminopropyl) triethoxysilane as monomers. Following the structural and morphological characterization of microparticles, the evaluation of template rebinding indicated a clear specificity of MIPs for LPS compared to the NIPs. Hybrid MIP/ZnONPs/CP and NIP/ZnONPs/CP inks were characterized using morphological and structural methods, which confirmed a viscosity of 25.000 mPa.s, a granulation of <20 µm, and a solid powder content of <27 %, as well as a homogenous incorporation of MIP particles and ZnONPs in the conductive CP. Finally, the electrochemical evaluation of the modified MIP/ZnONPs/CP@SPCE sensor revealed a good sensitivity to LPS molecules in PBS at pH 7.4, in the linear working range 1 - 100 µM, where a 0.058 µM limit of detection (LOD) and a response time less than or equal to 1 min were determined. The selectivity of the MIP/ZnONPs/CP@SPCE sensor towards LPS from Salmonella enterica and Escherichia coli was also assessed, highlighting a clear difference between these structural resembling species.

A robust aerogel incorporated with phthalocyanine-based porous organic polymers for highly efficient gold extraction

The gold recovery from electronic waste liquid is of great significance to the recycling of precious metals and environmental restoration. Adsorption method is the preferred technique for gold recovery, but its expansion and application prospects were often limited by the workability and recyclability of common solid powder adsorbents. Herein, a solid absorbent powder (phthalocyanine-based POP, TD-POP) was integrated into chitosan/polyethyleneimine aerogel (TD-POP@CS/PEI-2) via a facile cross-linking and lyophilization strategy. As expected, TD-POP@CS/PEI-2 possessed outstanding mechanical toughness and stability, demonstrating efficient and specific adsorption for Au (III). The maximum adsorption capacity was 2169 mg g−1, higher than most of the absorbents. TD-POP@CS/PEI-2 aerogel also exhibited fast kinetics (recovery efficiency of 81.3 % within 3 h), good selectivity (recovery efficiency of 98.35 % at 10 times concentration of Al3+, Zn2+, Cu2+ Cd2+, Co2+, Ni2+, Mn2+, and Cr6+ than Au ions) and reusability (eight times). Multiple characterizations revealed the adsorption mechanism, which implied that the excellent adsorption properties of the aerogel were ascribed to the electrostatic attraction between cationic aerogel and AuCl4− anion, coordination interaction between nitrogen-containing active sites and Au (III), and reduction of Au (III) by TD-POP@CS/PEI-2 aerogel. This work provides a valuable and promising strategy to design scalable and sustainable adsorbents for capture precious metals, also promotes the development of integral adsorbent for environmental remediation.

Establishment and evaluation of dynamic viscoelasticity constitutive model for asphalt mixtures based on PCA model: Utilizing coal-based synthetic natural gas slag and phosphogypsum whisker as substitute fillers

To promote the secondary utilization of solid waste in asphalt pavement and reduce resource waste and environmental damage, the fine solid waste powder from the secondary treatment of solid waste was used as a substitute filler to prepare asphalt mixtures. To more precisely characterize the effects of filler type and substitution ratio on the dynamic viscoelastic mechanical characteristics of asphalt mixtures, the dynamic modulus test was conducted on asphalt mixtures, while the dynamic modulus master curve of asphalt mixtures was established based on the time-temperature equivalent principle and the Sigmoidal function. The improved generalized Sigmoidal (IGS) model, five-parameter fractional Zener (FFZ) model, six-parameter fractional Zener (SFZ) model and ten-parameter fractional Zener (TFZ) model were used to construct the shrinkage frequency curves of different asphalt mixtures under different constitutive relationships, whereas the applicability of the constitutive models was further evaluated by the principal component analysis (PCA) model. The research results showed that the dynamic modulus and phase angle of the mixture exhibited a similar change rule with the variation of temperature and frequency, and the use of solid waste-based fillers could effectively reduce the effect of frequency variation on the viscoelasticity of the mixture. The dynamic modulus master curve constructed by Sigmoidal function could accurately describe the functional relationship between the dynamic modulus with loading frequency and temperature, and the variation trend of dynamic modulus in a wider frequency range was flattened with the increase in frequency, and this change rule was not affected by the substitution ratio of the filler, while the use of solid waste-based filler could reduce the dependence of the mixture on the temperature. Compared to several fractional constitutive models, the IGS model exhibited a higher fitting accuracy for the dynamic viscoelasticity of several mixtures, and with the use of solid waste-based fillers, the deviation of fitting curves gradually decreased. A comparative study showed that the fractional constitutive model was difficult to accurately describe the dynamic viscoelasticity of the mixture, and the IGS model was preferred to be recommended as a calculation model to investigate the constitutive relationship on the dynamic viscoelasticity of the mixture.

Ablation resistance of (Hf⅓Zr⅓Ta⅓)C solid solution ceramic coating for carbon/carbon composites at 2100 °C

Multicomponent solid solution ceramics have attracted extensive attention for their superior ablation resistance and high-temperature resistance, which are expected to extend the service life of carbon/carbon (C/C) composites under an ablation environment above 2000 °C. Herein, we synthesized (Hf⅓Zr⅓Ta⅓)C solid solution ceramic powders via carbothermal reduction. Then a dense (Hf⅓Zr⅓Ta⅓)C solid solution ceramic coating was deposited on SiC-coated C/C composites by supersonic atmospheric plasma spraying. The coated samples exhibited a low linear ablation rate of −0.61 μm/s after ablation for 120 s, mainly associated with the formation of a compact oxide scale consisting of (Hf, Zr)6Ta2O17 and (Hf, Zr)O2. The refractory (Hf, Zr)O2 skeleton structure possessed good thermal endurance, and the Ta-rich oxide melt filled the defects of the skeleton.