Laser induced crystallization in lithium borate-bismuth tungstate glass-ceramic for photocatalytic dye degradation

This research presents the first study on laser-induced crystallization to prepare glass-ceramics for water-cleaning applications. In previous reports, glass crystallization was accomplished through heat treatment at a specific temperature determined by performing differential scanning calorimetry (DSC). The new method proposed in this study offers advantages in terms of speed, control, less damage, less contamination, and miniaturization for the crystallization of glass-ceramics. Lithium borate-bismuth tungstate glasses were prepared using the conventional melt-quench technique and then crystallized using a laser power source. The resulting glass-ceramic was analyzed using X-ray diffraction (XRD) and Raman spectroscopy to determine its structure and phase, while field-emission scanning electron microscopy (FE-SEM) was used to examine its morphology. The band gap of the glass-ceramic was determined to be 2.8 eV using UV–vis spectroscopy. The photocatalytic degradation of methylene blue dye (MB) was used as a model, achieving 65% degradation within 240 min of visible light irradiation.     

Absence of surface flaking in hierarchical glass-ceramic coating: High impact resistant ceramic tiles

The impact resistance method is a useful procedure to determine the tile resistance. While other works are focused on modifying the tile support to improve the impact resistance, in this work, a new glass-ceramic material was developed to used it as glaze coating in order to relax impact tensions. This material possesses a hierarchical nano-microstructure consisted of microcrystal surrounded by nanostructured regions having low glassy phase, which is considered responsible for tension relaxations. The resilience coefficient measured in conventional and glass-ceramic glazes presents little differences (0.85–0.88). However, impact damages on the surface is totally inhibited for glass-ceramic coating while the conventional one suffers great flaking. These damages were analyzed by Optical profilometry and FESEM to compare the impact resistance and to correlate it with its microstructure. The results confirm that the micro-nanostructured coating paves the way to improve impact resistance in ceramic materials where surface damage is a critical parameter.     

ZnS基发光陶瓷釉的研制及发光机理探讨

本文介绍了ZnS基发光粉及其发光陶瓷釉的制备工艺，并对其发光机理进行了分析探讨。     

Kinetics and in situ observation of nonisothermal crystallization in Bayan Obo tailing-based nanocrystalline glass-ceramic

In recent years, the preparation of CMAS nanocrystalline glass-ceramics has shown potential as an application of secondary resourcing technology in utilizing Bayan Obo iron ore tailings containing rare earth elements. The crystallization mechanism for nanodiopside-type glass-ceramics was studied via an investigation of the nonisothermal crystallization kinetics of the glass system, combined with the in situ observation of softening and crystallization of the basic glass using a high-temperature laser confocal microscope. The results show that the activation energy of nucleation in the glass system is higher than that of crystal growth by using the Ozawa model. The crystallization mechanism changes as the crystallization fraction increases, that is, from the three-dimensional growth in which the nucleation rate increases with time in an interface-controlled manner (a > 1, b = 1, m = 3) at the initial stage of crystallization to a decreased nucleation rate in a diffusion-controlled growth (a = 0.5, b = 0.5, m = 3) at the middle and later stages. This process involves both surface crystallization and volume crystallization. The crystallization was observed in situ, and it was further confirmed that there exists a critical nucleation temperature between T_g and T_x, which is related to the interface free energy and critical Gibbs free energy difference. When the temperature exceeds the critical value of T_g + 55 K, the system begins to exhibit visible crystallization. With an increase in temperature, the basic glass softened considerably, while the crystal grew significantly. In addition, the surface roughness can be used to characterize the crystallization process, providing a new research method for crystal growth.     

Rutile-perovskite multi-phase composite by mechano-chemical method together with calcination: Preparation and application in coatings and ceramic glaze

In this article, rutile-perovskite multi-phase composite was produced using mechano-chemical method followed by calcination with metatitanic acid and GCC as raw materials. The relative parameters in mechano-chemical method, such as slurry concentration, grinding time and ball to powder ratio, and the relative parameters in calcination, namely calcination temperature and calcination time, were researched systematically in order to get the optimum value. The structure and morphology of the final product were characterized and the reaction mechanism was investigated. The final product, namely the rutile-perovskite multi-phase composite, has excellent pigment properties comparable to titanium white. It also has excellent performances in coatings and ceramic glaze. All of these prove that the produced rutile-perovskite multi-phase composite can be used extensively in industry due to its excellent pigment properties together with simple reaction conditions.     

Near infrared persistent luminescence of transparent Zn-Ga-Ge-O:Cr3+ glass ceramic for optical information storage

Cr³⁺-doped near-infrared (NIR) afterglow phosphors have received wide recognition in the optical storage field because of the high signal-to-noise ratio and broad excitation spectra. In this article, the high-temperature TL intensity of ZnGa₂O₄:Cr³⁺ afterglow glass ceramic (ZGO:Cr³⁺ GC) was enhanced via partial hetero-valence substitution of Ge for Ga, demonstrating the tunability of the trapped electron levels in ZGO:Cr³⁺ GC. The persistent luminescence phosphor ZGO:Cr³⁺ GC exhibits a zero-phonon lines emission peaking at 698 nm, attributing to the ²E→⁴A_2g transition of Cr³⁺ ions. Moreover, the trap levels in Zn-Ga-Ge-O:Cr³⁺ glass ceramic (ZGGO:Cr³⁺ GC) are deeper than those of the Ge-free one and the captured electrons in deeper levels cannot be released only by the ambient thermal energy, thus the optical storage capacity of ZGGO:Cr³⁺ GC is much larger. By means of an additional 980 nm laser photostimulation, an intense NIR emission could be obtained. In consequence, ZGGO:Cr³⁺ GC has a promising application prospect in optical information storage field.     

Preparation and antibacterial activity of Ag/TiO2-functionalized ceramic tiles

An Ag/TiO₂ coating was deposited onto glazed ceramic tiles by a sol-gel and spraying method at high temperatures. The coating was characterized by X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The results showed that silver was present in rutile-TiO₂, and the temperature did not change the phase composition of the samples. The Ag/TiO₂ coating had a higher roughness than the TiO₂ coating. The tape test (D 3359–08) showed that the coatings prepared at 950 °C and 1000 °C had good adhesion to the ceramic tile substrate. The antibacterial activity of the coating was tested by photocatalytic sterilization experiments. The results showed that the Ag/TiO₂ coating had a higher antibacterial activity than the TiO₂ coating, and the sterilization efficiency of Escherichia coli, Staphylococcus aureus, Shigella, and Salmonella exceeded 99.655% under 2 h of visible light irradiation. This research provides a method to create Ag/TiO₂ coatings with good thermal resistance, adhesion, and antibacterial activity. This improves the low photocatalytic activity caused by the anatase-to-rutile transformation of TiO₂ at high temperatures and the poor adhesion at low temperatures.     

Effect of surface nucleation on isothermal crystallization kinetics: Theory, simulation and experiment

Surface nucleation of poly(l/d-lactide) at the interface with aluminum was studied by performing isothermal DSC analysis of amorphous samples of varying thickness between 100 °C and 130 °C. To ensure complete wetting of the aluminum surface, a hot melt laminating process was used to prepare the samples. Theoretical aspects of surface crystallization kinetics were explored and the resulting model was compared with the results of Monte-Carlo simulations. Three stages of surface crystallization were identified depending on the growth geometry: (1) impingement-free growth, (2) increasingly laterally-constrained transverse growth, and (3) interstitial growth. By fitting the Monte-Carlo simulation to the experimental half-times of crystallization the surface nucleation concentration and the bulk nucleation rate was estimated at 4 different temperatures. It was found that both surface nucleation concentration and the bulk nucleation concentration decrease with increasing crystallization temperature.     

High pressure and high temperature treatment of chemical vapor deposited polycrystalline diamond: From opaque to transparent

The enhanced optical properties of chemical vapor deposited (CVD) diamond have been pursued in academia and industry for many applications. However, the barrier of CVD technology limits the application field of diamond. Herein, the performance of CVD polycrystalline diamond thick films was improved by high-pressure and high-temperature (HPHT) treatment. The microstructures of CVD polycrystalline diamond films before and after HPHT treatments were thoroughly examined using optical microscope, UV–visible and infrared absorption, Raman spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM). It is found that the transparency of the CVD samples at 10 GPa increases dramatically with processing temperatures, from the original opacity to almost full optical transparency. Through spectroscopic and microstructural analyses, the modification mechanism of CVD polycrystalline diamond under HPHT conditions is proposed. The results show that the HPHT treatment can significantly enhance the optical properties of the starting CVD polycrystalline diamond films.     

Development of a hoop-strength test for model sphero-cylindrical dental ceramic crowns: FEA and fractography

Here we describe the development of a mechanical test that simulates a circumferential “hoop-stress” at the margins of model dental ceramic crowns. A simplified sphero-cylindrical geometry was modelled in two thicknesses and machined out of two glass-ceramic materials. The specimens were loaded by a conical metallic piston to induce circumferential hoop-stresses at the margins until fracture. Broken specimens were fractographically analyzed to determine the location of the fracture origin and to measure the dimensions of the critical defect, allowing the calculation of the stress at failure from fracture mechanics relations. For thick specimens, machining defects at the outer margins barely played a role in fracture initiation. For thin specimens, outer defects started to dominate the failure mode. CAD/CAM machining showed to predispose thinner margins to early fracture. Crowns should be designed with increased thickness in order to minimize the effect of marginal damage in the circumferential stress field inducing fracture.     

Eu3+ doped ferroelectric CaBi2Ta2O9 based glass-ceramic nanocomposites: Crystallization kinetics,optical and dielectric properties

We report Eu³⁺ doped transparent glass-ceramics (GCs) containing bismuth layer-structured ferroelectric (BLSF) CaBi₂Ta₂O₉ (CBT) as the major crystal phase. The CBT crystal phase was generated in a silica rich glass matrix of SiO₂-K₂O-CaO-Bi₂O₃-Ta₂O₅ glass system synthesized by melt quenching technique followed by controlled crystallization through ceramming heat-treatment. Non-isothermal DSC study was conducted to analyze crystallization kinetics of the glass in order to understand the crystallization mechanism. The optimum heat-treatment protocol for ceramization of precursor glass that has been determined through crystallization kinetics analysis was employed to fabricate transparent GCs containing CBT nanocrystals, which was otherwise difficult. Structural analysis of the GCs was carried out using XRD, TEM, FESEM and Raman spectroscopy and results confirmed the existence of CBT nanocrystals. The transmittance and optical band gap energies of the GCs were found to be less when compared to the precursor glass. The refractive indices of the GCs were increased monotonically with increase in heat-treatment time, signaling densification of samples upon heat-treatment. The dielectric constants (ε_r) of the GCs were progressively increased with increase in heat-treatment duration indicating evolution of ferroelectric CBT crystals phase upon heat-treatment.     

Ultrasound assisted crystallization of cephalexin monohydrate:Nucleation mechanism and crystal habit control

With the high-quality requirements for cephalexin monohydrate,developing a robust and practical crys-tallization process to produce cephalexin monohydrate with good crystal habit,appropriate aspect ratio and high bulk density as well as suitable flowability is urgently needed.This research has explored the influence of ultrasound on crystallization of cephalexin monohydrate in terms of nucleation mechanism and crystal habit control.The results of metastable zone width and induction time measurement showed the presence of ultrasound irradiation can narrow the metastable zone and shorten induction time.Cavitation phenomena generated by ultrasound were used to qualitatively explain the mechanism of ultrasound promoting nucleation of cephalexin monohydrate.Furthermore,on the basis of classical nucleation theory and induction time data,a series of nucleation-related parameters (such as crystal-liquid interfacial tension,radius of the critical nucleus and etc.) were calculated and showed a decreasing trend under ultrasound irradiation.The diffusion coefficient of the studied system was also determined to increase by 72.73％ under ultrasound.The changes in these parameters have quantitatively confirmed the mechanism of ultrasound influence on the nucleation process.In further,the calculated surface entropy factor has confirmed that the growth of cephalexin monohydrate follows continuous growth mechanism under the research conditions of this work.Through the exploration of crystallization conditions,it is found that suitable ultrasonic treatment,seeding,supersaturation control and removal of fine crystals are conducive to improving the quality of cephalexin monohydrate product.Optimizing the crystalliza-tion process coupled continuous ultrasound irradiation with fine-crystal dissolution policy has achieved the controllable production of monodisperse cephalexin monohydrate crystal with good performance.     

Simulation and analysis of industrial crystallization processes through multidimensional population balance equations. Part 1: a resolution algorithm based on the method of classes

In order to obtain constant solid properties with particles exhibiting a low order of symmetry, it is necessary to monitor and to control several distributed parameters characterising the crystal shape and size. A bi-dimensional population balance model was developed to simulate the time variations of two characteristic sizes of crystals. The nonlinear population balance equations were solved numerically over the bi-dimensional size domain using the so-called method of classes. An effort was made to improve usual simulation studies through the introduction of physical knowledge in the kinetic laws involved during nucleation and growth phenomena of complex organic products. The performances of the simulation algorithm were successfully assessed through the reproduction of two well-known theoretical and experimental features of ideal continuous crystallization processes: the computation of size-independent growth rates from the plot of the steady-state crystal size distribution and the possibility for MSMPR crystallizers to exhibit low-frequency oscillatory behaviours in the case of insufficient secondary nucleation.     

PVD hard coatings on ceramic tiles for aesthetic applications: surface characterisation and corrosion properties

The development of innovative ceramic tiles looks for materials with improved mechanical and tribological properties as well as a higher corrosion resistance (high relative humidity, daily watering, household chemical cleaners). In addition, a greater durability leads to lower environmental impact. Along with their improved functionality and recyclability, ceramic tiles should also provide aesthetic properties. Ceramic tiles can be treated to modify the physico-chemical properties of the surface by metal coatings or metallic compounds, also providing an attractive metallic sheen appearance. In the present paper, titanium nitride (TiN) and zirconium nitride (ZrN) coatings were deposited on glazed porcelain stoneware by an industrial PVD multicathode arc deposition system under a reactive nitrogen atmosphere. After the process, the tiles showed a gold-like colour, a smooth surface and a coating thickness between 0.7 and 1.6 μm. The coating composition, scratch resistance and corrosion behaviour have been evaluated. It can be concluded that both coatings are suitable for use in domestic environments due to their stability and resistance to aggressive conditions. Few references have been found regarding these coatings on ceramic tiles for domestic and industrial applications, but it has been proved that they bring added value to traditional ceramics, giving new functional properties of ceramics both decorative and highly corrosion and mechanical resistance.     

Preparation of transparent nanocomposites from UV‐ and thermo‐curable epoxyacrylate and graphene oxide for the application of corrosion protection coatings

In this study, we report UV‐ and thermo‐curable epoxyacrylate/graphene oxide (EA/GO) nanocomposites that present good transparency, excellent pencil hardness and promising improvement in corrosion protection. A dual‐curable EA oligomer with one terminal epoxide and one double bond at the other end was synthesized by reaction of diglycidyl ether of bisphenol‐A and acrylic acid. After mixing EA and GO with the curing agents and reactive diluent followed by UV cure and thermo‐cure, the resulting EA/GO films on a glass slide with GO loading up to 3 phr exhibited over 86% light transmittance. Furthermore, the pencil hardness was enhanced from 3H for EA to 6H for the EA/GO composite at 2 phr GO loading. The corrosion protection of the EA/GO coatings was evaluated by a potentiodynamic polarization technique and electrochemical impedance spectra. The corrosion potential (E_corr) of the EA/GO‐coated steel increased with increasing GO loading. Meanwhile, Nyquist and Bode plots indicated that the higher the GO content in the EA/GO coating was, the higher was the coating resistance and also the charge transfer resistance after immersion in salt solution. All these results proved that the GO had positive effects on enhancement of the corrosion resistance. The improved corrosion protection by the EA/GO coatings was mainly due to the enhanced hydrophobicity, the deviation of electron transfer and the increased tortuosity of the diffusion path. The improved corrosion protection and hardness together with the useful dual‐curability make the EA/GO nanocomposite a competitive candidate for corrosion protection coatings. © 2019 Society of Chemical Industry     

Dynamic modeling of a batch crystallization process: A stochastic approach for agglomeration and attrition process

This paper deals with the dynamic modeling of a batch crystallizer. A complete model taking into account primary and secondary nucleations, crystal growth, agglomeration and attrition mechanisms is established. The proposed model is not restricted to binary agglomeration and breakage phenomena. From markovian considerations, continuous kernel functions are built and the basic balance equations are then presented. The complete model is solved using a finite difference method for the discretization of the size variable. As to distinguish agglomeration and breakage parameters from the others, on line measurement of the Crystal Size Distribution is necessary, a new on line measurement strategy is proposed. Finally, simulations of the crystal size distribution are compared with experimental results at different times. It appears that simulated curves are in good agreement with the experimental data.     

Non-isothermal crystallization kinetics of Nylon 10T and Nylon 10T/1010 copolymers: Effect of sebacic acid as a third comonomer

Nylon 10T and Nylon 10T/1010 samples were synthesized by direct melt polymerization.The non-isothermal crystallization kinetics of Nylon 10T and Nylon 10T/1010 was investigated by means of differential scanning calorimetry (DSC).Jeziomy equation and Mo equation were applied to describe the non-isothermal crystallization kinetics of the Nylon 10T and the Nylon 10T/1010.The activation energies for non-isothermal crystallization were obtained by Vyazovkin's method and Friedman's method,respectively.These results showed that Jeziorny equation and Mo equation well described the non-isothermal crystallization kinetics of the Nylon 10T and the Nylon 10T/1010.It was found that the values of the activation energy for non-isothermal crystallization of the Nylon 10T/1010 were lower than those of the Nylon 10T at a given temperature or relative crystallinity degree,which revealed that crystallization ability of the Nylon 10T/1010 was higher.The crystal morphology was observed by means of a polarized optical microscope (POM) and X-ray diffraction (XRD).It was found that the addition of sebacic acid comonomer not only did not change the crystal form of the Nylon 10T,but also significantly increased the number and decreased the size of spherulites.Comparing with the Nylon 10T,the crystallization rate was increased with the addition of the sebacic acid comonomer.     

高温熔烧法制备金属基陶瓷涂层的研究

以玻璃熔块、氧化铬粉、粘土粉和硅酸锆微粉为原料制成的涂料,用滚涂法将其均匀涂覆在不锈钢管上,经高温(1000~1050℃保温20min)熔烧制备出了耐磨、抗高温氧化的陶瓷涂层。对陶瓷涂层的耐磨性、抗高温氧化性、抗热震性等性能进行了测试,并对影响涂层性能的因素进行了研究。结果表明:引入具有较大热膨胀系数的玻璃熔块料有利于提高涂层结合性;加涂层的试样均能明显改善基体的耐磨性和抗高温氧化性。涂层的耐磨性随硅酸锆微粉加入量的增加而提高,加入量为15%时耐磨性和抗热震性最好,其热震循环(1000℃空冷)可达22次。     

Preparation of CuMn2O4/Ti3C2 MXene composite electrodes for supercapacitors with high energy density and study on their charge transfer kinetics

In this study, we present a novel electrode material that combines Ti₃C₂ MXene and high-capacity CuMn₂O₄ to increase the energy density of supercapacitors, which are a popular choice for energy storage due to their high-performance potential. The electrode material was synthesized using the hydrothermal method with varying deposition times (3 h, 6 h and 9 h), and the resulting composite materials were characterized using advanced analytical techniques. The CuMn₂O₄/MXene composite electrode synthesized at 3h exhibited exceptional performance, with a specific capacitance of 628 mF/cm² at 4 mA/cm², due to the enhanced electrical conductivity and charge storage properties of CuMn₂O₄ and MXene sheets. We also uncovered an intricate charge transfer mechanism and storage kinetics of CuMn₂O₄/MXene composite on a nickel foam electrode, revealing a diffusion-controlled energy storage mechanism with fast mass transportation. To demonstrate practicality, we constructed an asymmetric coin cell supercapacitor device using CuMn₂O₄/MXene composite synthesized at 3h and activated carbon as the positive and negative electrodes, respectively. The device showed a specific capacitance of 496 mF/cm² at 6 mA/cm² with cyclic stability of 80% for up to 10,000 cycles, and a power density of 1.5 mW/cm² at a higher energy density of 0.073 mWh/cm². Our results demonstrate the potential to significantly advance the development of high-performance supercapacitors by combining Ti₃C₂ MXene and high-capacity oxides, refining the synthesis process, and exploring innovative electrode architectures.     

Preparation of transparent Mn-doped CaF2 glass-ceramics from silicon-manganese slag: Dependence of colour-controllable change on slag addition and crystallization behavior

Silicon-manganese slag was firstly used to prepare the transparent colour-controlled glass-ceramics containing Mn-doped CaF₂ nanocrystals. The maximum utilization ratio of slag reaches to 27.04 wt%, and the colour of the samples trended red-brown to red light as the added slag content increased. The transparent glass-ceramics could be prepared when crystallized between 650 and 710 °C for 2 h, and had a minimum transmittance of 67.95 % at a wavelength of 780 nm. Increasing the content of added slag caused the emission spectrum to shift, demonstrating the ability to control the colour of the transparent glass-ceramics, and also enhanced the fluorescence intensity. The crystallization behaviour conversely has little effect on the colour change, but can increase the fluorescence intensity. In general, this work provides a new approach for the comprehensive utilization of silicon-manganese slag for applications in optical engineering.