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In the present study, four fired clay bricks recipes with addition of recycled waste ceramics resulted from building demolition and waste paper pulp as pore-forming agent in different proportions are investigated. The purpose of the work is to analyse the impact of pore-forming agent and wastes on the physical, mechanical and thermal properties of the resulting products. The raw materials and the samples were analysed from chemical, mechanical and thermophysical point of view by XRD, SEM with EDX analysis, lock-in thermography and PPE calorimetry techniques, mercury porosimetry and image analysis. It was found that the compressive strength decreases from 53 MPa for a porosity of 3.5% until 7 MPa for a porosity of 35%, while the thermal conductivity varies from 0.75 to 0.58 W m−1 K−1. [ABSTRACT FROM AUTHOR]

A novel approach based on the preceramic paper method was used for the fabrication of Ti3SiC2-based material. Elemental powders of Ti, TiC, Si, C, and organic additives were used as starting materials. The Rapid Köthen process was used to fabricate the preceramic papers. The high-loaded green body of preceramic papers was heat-treated up to varying temperatures of 1300, 1400, 1500, and 1600 °C for 1 h in an Ar atmosphere. By using an excess amount of Si powder in the basic composition, the amount of Ti3SiC2 in the sintered specimen could be increased while the amount of TiC could be reduced. X-ray analysis showed that the paper-derived sample with the basic powder composition 3Ti/3TiC/3Si/C was a single phase within the resolution limit of the instrument used. The high purity of Ti3SiC2 can be explained by the partial formation of amorphous C which could not be detected by X-ray diffraction. Scanning electron microscopy analysis of fracture surfaces showed the characteristic lamellar structure of the paper-derived MAX phase. [ABSTRACT FROM AUTHOR]

Novel ceramics from waste material made of (x) paper ash-(80 - x) cullet-20 kaolin clay (10wt% ≤ x ≤ 30wt%) were successfully synthesized using a conventional solid-state reaction technique. Energy-dispersive X-ray analysis confirmed the presence of Si, Ca, Al, and Fe in the waste material for preparing these ceramics. The influence of the cullet content on the phase structures and the dielectric properties of these ceramics were systematically investigated. The impedance spectra were verified in the range from 1 Hz to 10 MHz at room temperature. The phase of the ceramics was found to primarily consist of wollastonite (CaSiO3), along with minor phases of γ-dicalcium silicate (Ca2SiO4) and quartz (SiO2). The sample with a cullet content of 55wt% possessed the optimum wollastonite structure and exhibited good dielectric properties. An increase of the cullet content beyond 55wt% resulted in a structural change from wollastonite to dicalcium silicate, a decrease in dielectric constant, and an increase in dielectric loss. All experimental results suggested that these novel ceramics from waste are applicable for electronic devices. [ABSTRACT FROM AUTHOR]

Three-dimensional digital technology has made breakthroughs and shown unique advantages in all walks of life. On the basis of practicality, the three-dimensional artistic design of ceramic products gradually adds some aesthetic, artistic design elements, which brings beautiful enjoyment to people's lives and makes people's lives colorful. This paper presents a three-dimensional artistic design method for ceramic products based on RNN (recurrent neural network) technology. With the establishment of the 3D YOLOv3 framework, the new model training is faster and more stable, the convergence speed of the loss function is faster, and the reconstructed 3D model is more accurate. After training for a certain number of times, the network gradually becomes stable, the accuracy rate is kept at 95%, and the loss function value is reduced below 0.2. The accuracy of the network model and the precision of semantic segmentation are improved. The semantic segmentation and object recognition under 3D scene reconstruction studied in this paper have certain theoretical value and high feasibility. [ABSTRACT FROM AUTHOR]

The article offers information about the Journal of Thermal Spray Technology Volume 24 Best Paper Award winners including "Plasma Spraying of Ceramics with Particular Difficulties in Processing," by Georg Mauer and colleagues, "Process-Property Relationship for Air Plasma-Sprayed Gadolinium Zirconate Coatings," by Gopal Dwivedi and colleagues and "Microstructural Analysis of Cold-Sprayed Ti-6Al-4V at the Micro- and Nano-Scale," by Aaron Birt and colleagues.

This comment on the above three papers argues that the crystals should be of sillenite type and the correct formula should be Bi25FeO39:MTi (M = Co or Ni) instead of BiFeO3. Due to the doping, a new type of unit cell, previously unknown, was proposed for such crystals. There is also about 15% of a secondary phase, BiFeO3, in the sample. This part of the sample should be responsible for the magnetic properties recorded. [ABSTRACT FROM AUTHOR]

The 1D moisture diffusivity of porous materials may strongly depend on the content of moisture in the materials, varying over an order of magnitude or more. In this paper we present a new model from which the diffusivity can be evaluated, using the pore size distribution and water absorption coefficient. We point out that this is a more efficient approach than the standard Boltzmann–Matano (BM) method, because measurements of pore curves and water absorption are much shorter and rather accurate compared to moisture profile experiments needed in the BM method. As an example, we apply our model to two samples of a ceramic brick for which experimental data on both pore curves and moisture profiles had been measured. A very good quantitative agreement in the diffusivity is obtained for early stage profiles. For later stages, however, the model predicts three to four times higher diffusivity than the BM method. The reasons for this discrepancy are discussed and further tasks to validate the effectiveness of the new model are proposed. We also compare our model with the pore models of Burdine and Mualem. [ABSTRACT FROM AUTHOR]

The valorization of phosphate mine waste (PMW) in different fields has recently become attractive to many researchers. This review paper examines the potential use of PMW as a raw material in different applications toward sustainable management strategies. Dewatering, recovery of phosphate and heavy metals, building materials and ceramics applications have been captured in this paper. Based on the origin of deposit and the treatment during ore beneficiation, the PMW shows different mineral compositions and various percentage of chemical elements which make it suitable for most of the studied applications. The objective of this paper is to show the potential of the phosphate mine waste valorization and to identify the knowledge gap. [ABSTRACT FROM AUTHOR]

This paper reports experimental investigations on cold plates made from Low-Temperature Co-fired Ceramic (LTCC) technology for liquid cooling of supercomputer microprocessors. LTCC, a ceramic substrate-based technology with lightweight and ease of fabrication for miniaturization of cooling devices, can be a potential alternative to the existing copper cold plates for future three-dimensional stacked chip architectures. LTCC cold plates were fabricated using ceramic substrates whose thermal conductivity was enhanced using thermal vias. They were embedded with microchannels for liquid with different flow configurations. Their thermal performance is compared against copper cold plates. Deionized (DI) water is used as a coolant. Pressure drop and thermal resistance across different cold plates are measured as per water-cooled data center standards (W3 and W4 class). Obtained experimental results show that the tested LTCC cold plates can be used to cool supercomputer processors. It is concluded that LTCC cold plates can be a potential alternative for existing copper cold plates. [ABSTRACT FROM AUTHOR]

Worldwide, coarse dispersed kaolins are produced as a major proportion of the processing of a primary product. The superfine structure of the Bulgarian kaolins, due to their sediment (secondary) origin, is a problem. The company Kaolin AD has produced coarse dispersed kaolin using high energy-intensive separating centrifuges. The aim of this investigation is to study the possibility of obtaining coarse dispersed kaolin through a lower-energy method -- hydrocycloning. This investigation shows that the lower hydrocycloned products, with regard to particle size and chemical composition, are analogues of the coarse centrifugal separated kaolin. The upper hydrocycloned product/second configuration, in terms of particle size and chemical content, is a complete analogue of the fine centrifugal separated kaolin. The hydrocycloned overflow in the first configuration is a new product, intended for paper coating. [ABSTRACT FROM AUTHOR]

Squeeze flow has been proven as an interesting technique for the rheological evaluation of many classes of materials, being relatable to common compressive phenomena from various processing and application procedures. Despite the simplicity of the experimental setup needed to run it, the results from the test are rather complex, involving multiple variables and factors that are not fully clarified by the bulk stress response. One additional piece of information that can be valuable is the pressure distribution over the sample area, since it is related to key aspects of the flow. The addition of a pressure mapping system to the traditional setup of the test has been recently proposed as a way to enrich the information obtained, in a method deemed pressure mapped squeeze flow (PMSF). This paper presents the evolution and state of the art of this technique, and analyzes a plastic clay with two different water contents in three displacement rates to demonstrate the potential and possibilities that PMSF offers. The experimental setup is presented in detail, along with the calibration procedure and data treatment suggested, as well as multiple types of analyses including bulk stress curves, raw pressure distribution plots, measured contact area, evolution of the mean profile, comparison to theoretical models supported by error analysis, and investigation of variation over the area. With the procedure established and presented in this work, it should be possible to apply PMSF as a valuable technique throughout the materials science and engineering community. [ABSTRACT FROM AUTHOR]

This paper studied Late Iron Age ceramic fragments from Nditam village (Centre Region, Cameroon), the technological features and deduced the type of the raw materials used to produce them by combining different analytical techniques based on X-ray fluorescence, powder X-ray diffraction, thermogravimetry, polarized optical microscopy, spectrophotometry and hydric tests. Macroscopic observations suggest the existence of three types of ceramics according to their colour, black, greyish and red, in the two opposite surfaces, outer (or external) and inner (internal). The chemistry indicates that non-calcareous clayey material was used for ceramic production. The correlation between mineralogy, petrography and the geology of the region suggests a local production of ceramics. Moreover, the chemistry of the samples confirms the existence of the three macroscopic groups and suggests the use of local raw materials for their production. From the mineralogical point of view, quartz, feldspar and mica (biotite and muscovite) were identified in all the samples, while kaolinite and amphibole were detected in some of them. The differences in the mineralogy may indicate some variations in the firing temperature, being lower in the ceramics containing kaolinite compared to the other samples. All the samples have similar water absorption behaviour. According to the colours of the ceramics, a prevalence of oxidising firing conditions was present in the kilns. However, partial reducing and short duration firing conditions were also possible. Comparative study with the mineralogy of ethnographic ceramics from southern Cameroon shows some similarities and suggests a continuity in the use of different local clay pits in this region over time. [ABSTRACT FROM AUTHOR]

Flexible energy harvesters have become a research hotspot in both academia and industry because of their great advantages in powering wearable electronic devices. The flexible energy harvesters based on piezoelectric materials are recognized as a competitive method because of their sensitivity to mechanical deformation, excellent energy conversion performance, mature production technology, and simple structure. This paper presents a comprehensive review to illustrate the research progress and future development of wearable flexible piezoelectric harvesters. In this work, the widely used piezoelectric materials for flexible energy harvesters, including inorganic piezoelectric materials, organic piezoelectric materials, and piezoelectric composites, are first summarized. The research progress on the influence of ceramic content, morphology, distribution, surface chemical modification, and the addition of conductive materials on the properties of piezoelectric composites are systematically discussed. Additionally, this paper also presents novel structures and fabrication methods of flexible piezoelectric energy harvesters. Finally, future trends in research, development, and innovation of flexible piezoelectric energy harvesters are outlined and prospected. [ABSTRACT FROM AUTHOR]

In the recoating process of the high-viscosity ceramic stereolithography, a large amount of ceramic paste is accumulated in front of the blade, and the fluidity of the high-viscosity ceramic paste is poor. The blade imposes forces on the solid part below, which deforms the fine structures of the part, affecting the accuracy of the part. In the actual printing process, slender rod parts appear T-shaped. This paper aims to investigate the causes of this phenomenon and to predict the deformation rate of a part. The understanding of the deformation phenomena can be used as theoretical guidance for dimensions or support sizes when modeling parts. A two-dimensional model has been developed to study high-viscosity materials with non-Newtonian fluid properties and slender rod parts, using the phase field method and a dynamic mesh to restore the recoating process. An experimental setup, which mimics the recoating process in the high-viscosity ceramic stereolithography process, has been used to verify the results of simulations. The results show the force exerted by the blade only affects the top portion of the slender rod part, and that the time of greatest impact on the deformation is the moment when the blade is reaching the top of the slender rod, generating a deformation rate that is cubic to the height of the slender rod. [ABSTRACT FROM AUTHOR]

Total hip arthroplasty is one of the most successful and cost-effective surgical interventions performed in orthopedics. The performance of hip prosthesis depends on factors such as type of material, dimensions, type of contact and stresses induced. The present paper addresses the influence of various material combinations on the contact stress. The metal and ceramic combinations are considered. Normal force due to walking is considered to estimate the contact stresses analytically, using Von Mises stress theory. The various radial clearances between head and liner, obtained by considering different geometrical configurations, are used to calculate contact stresses for all hard-on-hard material combination. The variation of contact stress during natural biological activities, such as walking, sitting, climbing and stumbling, is tabulated and represented graphically. A linear relationship is observed between contact stress and radial clearance. Highest contact stress is observed in ceramic-on-ceramic combination across all activities. [ABSTRACT FROM AUTHOR]

This paper presents an in-depth study on the combustion synthesis, solid-solution formation, processing, and characterization of NbB2–HfB2 ceramics, aiming to explore their potential applications, particularly in industries requiring high-performance materials. We conducted macrokinetic measurements and fitted regression models to predict combustion temperature and velocity for compositions ranging from 50 to 100% HfB2. A combined method of ball milling and hot pressing was developed for processing the combustion products into dense ceramics. These methods resulted in samples with relative densities reaching 97%, hardness of up to 34 GPa, and Young's modulus of up to 530 GPa, with NbB2–50% HfB2 solid solution exhibiting the best mechanical properties. The study revealed a linear increase in thermal properties and density with the rise in HfB2 content. The thermal conductivity of the solid solutions in the Nb–Hf–B system ranged from 34 to 40 W/mK and was found to increase with temperature, making these ceramics suitable for ultra-high-temperature applications. The findings have significant implications for aerospace and high-performance engineering sectors and provide a solid foundation for further investigation of Nb–Hf–B ceramics under real-world operational conditions. [ABSTRACT FROM AUTHOR]

Lithography-based additive manufacturing methods emerged as a powerful method for manufacturing of complex-shaped ceramic parts with excellent functional and structural properties. This paper summarizes the current state of the art in this field by articulating technological challenges associated with printing of functional parts. In addition, the paper addresses process requirements towards further enhancing component quality. A key aspect for obtaining high-quality parts is related to controlling chemical composition and uniformity of the photopolymerizable slurries. The latter requires in-depth understanding of the underlying photochemical processes. Changes in the formulation of the resin as well as changes in the exposure strategy distinctly influence bond conversion and gelling, which, in turn, influence the properties of the green part during thermal processing. Properly optimized processes and material composition allow to target a variety of challenging applications including patient specific parts for digital dentistry, and 3D-printed ceramics which can operate in harsh environments, as may be required in aerospace or chemical engineering applications. The paper will also provide an outlook into novel opportunities for 3D-printed ceramics. [ABSTRACT FROM AUTHOR]

Grinding force is the most important characteristic parameter in the study of grinding machining mechanism, and it has an important influence on the quality of the machined surface and the service life of the grinding wheel. Accurate prediction of grinding force is significant to process improvement, machine tool design, and condition diagnosis. This paper uses the ABAQUS software to simulate the end grinding process of Si3N4 ceramics. In the abrasive removal model, in order to express the complex grinding conditions of the fine-grained grinding wheel better, this paper adopts the truncated polyhedral abrasive grain model, and the abrasive grains are randomly rotated multiple times to verify the model, which reduces the simulation grinding force error caused by the randomness of irregular abrasive grain model and improves the prediction accuracy. This paper establishes an abrasive grain distribution model, the unit number of abrasive grains is calculated from the equivalent volume of abrasive grains, and the grinding force of a single abrasive grain extends to the end surface; in the process simulation model, considering the influence of the change of radial linear velocity on the grinding force, the final grinding force is obtained by partitioning and summing. The experimental comparison shows that the grinding force model has high prediction accuracy in the end grinding with the fine-grained grinding wheel. [ABSTRACT FROM AUTHOR]

Handcrafting ceramic pottery in the traditional method or virtual reality (VR) with intricate surface details is still challenging for the ceramic and graphic artist. Free-form pottery modeling can be efficiently geometrically modeled with the right tools with detailed 3D print outputs, yet challenging to be manufactured using traditional art. The new advanced pottery VR simulation is a promising method to recreate the traditional pottery simulation for a better experience with some barriers. The challenges that arise from surface detail in pottery are a tedious task accomplished by mesh blending and retopology. This paper focuses on refining the VP application's performance by adding unique sound resonance as a more likely infinite geometric phenomenon textures, blending it into the basic shapes. This paper combines creativity and visual computing technologies such as VR, mesh blending, fixing errors, and 3D printing to bring the ceramic artist's imagination to life. We have used sound resonance with virtual pottery (VP) systems refinements to demonstrate several standard pottery methods from free form deformed pottery, retopology, mesh blended for surface details, and 3D printed pottery with materials including polymer and ceramic resins. [ABSTRACT FROM AUTHOR]

The lunar base is not only an experimental station for extraterrestrial space exploration but also a dwelling for humans performing this exploration. Building a lunar base presents numerous obstacles and requires environmental perception, feedback design, and construction methods. An integrated fabrication process that incorporates design, 3D printing workflow, and construction details to build a bionic, reconfigurable and high-performance lunar base prototype is presented in this paper. The research comprises the study of the lunar regolith 3D printing mechanism, the real-time control of powder laying and compaction procedure, and the development of a 3D printing tool end system. In this paper, many scientific questions regarding in situ fabrication on the lunar surface are raised and addressed with the proposal of a progressive optimization design method, the molding principle, and gradation strategy of lunar soil-polyaryletherketone (PAEK) hybrid powder, and the principle of dual-light field 3D laser printing. The feasibility of the technical strategy proposed in this paper is verified by the presented empirical samples. [ABSTRACT FROM AUTHOR]

The paper studies ceramic samples prepared using traditional ceramic technology also knows as conventional sintering. Samples were prepared from Eu3+ activated fine powders of gadolinium niobate-tantalates GdNb1−yTayO4 (y = 0, 0.7, 1); Eu3+ concentration was x = 0.01, 0.2 and 0.4. Powders were synthesized using nitrate solutions Gd and Eu and niobium and tantalum hydroxides. The hydroxides were coprecipitated from hydrofluoric acid solutions. Full-profile analysis (Rietveld refinement) of XRD (X-ray diffraction) patterns of polycrystals determined the phase composition and refined the parameters of the structure of solid solution phases depending on the Eu concentration. Morphological features of the microstructure have been studied for gadolinium niobate-tantalate ceramics Gd1−xEuxNb1−yTayO4 where y = 0, 0.7, 1 and x = 0.01, 0.2, 0.4. Their mechanical properties have been studied; strength characteristics (Young's modulus, microhardness) and critical stress intensity factor for mode I KIC have been estimated. The compositions and modes for producing ceramics with optimal mechanical properties have been determined. The photoluminescence (PL) has been studied in ceramic solid solutions in the visible range upon excitation by near UV (376 nm). The features of energy transfer between the host of ceramic GdNb1−yTayO4:Eu solid solution (y = 0; 0.7; 1) and 4fn-4fn levels of Eu in concentrations x = 0.01, 0.2 and 0.4 have been established. We have established that concentration quenching of PL in single-phase ceramics Gd1−xEuxNbO4 occurs above Eu concentration x > 0.01 and in ceramics Gd1−xEuxTaO4—at Eu concentration x > 0.2. The sample with the composition Gd0.99Eu0.01NbO4 demonstrated the maximal PL intensity among all other studied samples. The least PL intensity is observed in Gd0.99Eu0.01Nb0.3Ta0.7O4 relative to individual compounds of gadolinium niobates and tantalates, activated with Eu in the same concentration x = 0.01. The significant difference in Stark splitting of levels has been shown for solid solutions based on niobium (Gd1−xEuxNbO4) and tantalum (Gd1−xEuxTaO4). The compositions of ceramic GdNb1−yTayO4:Eu solid solution have been established which have maximum luminance. We have determined that the luminance of some of the studied samples exceeded the luminance of an industrial phosphor based on Y2O3:Eu3+. [ABSTRACT FROM AUTHOR]

Advanced ceramics are widely used in various industries like medical, automotive, and aerospace. Production of ceramic components has been constrained due to challenging machining procedures and the difficulty of forming complicated parts. Powder injection molding is one of the suitable methods to produce complex ceramics and overcome the difficulties of producing these parts. This paper investigates the effect of micro and nano powder addition on the rheological properties, segregation, and imbalance filling. For this purpose, different amounts of nano and micro SiC powder (5 wt%, 10 wt%, 15 wt%, and 20 wt% of micro SiC and 1-3 wt% of nano alumina) were added to alumina powder and the prepared feedstocks were injected at various flow rates. Rheological properties of feedstocks and segregation phenomenon in the green parts were investigated by rotational rheometer and thermogravimetric analyzer, respectively. As well as, mold filing, segregation and distribution of temperature during filling were simulated using Moldflow Synergy (Autodesk) 2019 software and compared to the experimental results. It was found that feedstocks containing 15 wt% micro SiC and 2 wt% nano SiC showed the best rheological behavior. The segregation phenomenon was observed in samples injected at flow rate of 15 cm3/s. No imbalance filling was observed in none of the samples, but by increasing the flow rate the segregation was intensified. [ABSTRACT FROM AUTHOR]

The paper presents the synthesis of the aluminum–zirconia titanate composite powder using a high-power fastelectron beam. It is shown that the electron-beam processing of the mixture of initial oxide powders leads to the formation of composite ceramics with a complex phase composition. It is found that the porosity of the powder mixture depends on the electron beam parameters, scanning, and beam-induced displacement rate of the cuvette. When selecting these parameters, it is possible to synthesize low-porosity ceramics, which shows the tendency of combining synthesis and sintering during the electron-beam processing. [ABSTRACT FROM AUTHOR]

Green and intelligent manufacturing has become the key direction of industrial production development. In-situ measuring and sintering simulation technologies play a key role in the modification of ceramic materials and the optimization of the sintering process. These two techniques can significantly alleviate the problems of wasted energy and resources in the ceramics production process, thus promoting the green development of the ceramics industry. Although both techniques have been widely used in the field of ceramic sintering, there is a lack of a comprehensive review of their applications. To better promote the application of these two technologies, this paper provides the first overview of the progress of the application of ceramic sintering in-situ measuring technology and systematically reviews the current research status of ceramic sintering simulation technology. Then it looks forward to the application prospect of these two technologies, synthesizes these two technologies, constructs the framework of digital twin ceramic sintering system for the first time, and analyzes the important role of these two technologies in the digital twin ceramic sintering system. [ABSTRACT FROM AUTHOR]

SiC-TiB2 composite ceramics of the solid-state has stable property in high temperature with wide application. In the paper, SiC-TiB2 composite ceramics was prepared by spark plasma sintering with 50 MPa pressure and heat preservation for 10 min at 1750 ℃, and the effect of TiB2 content (0 vo l%-20 vol%) on microstructure and mechanical properties of SiC composite ceramics by solid-state spark plasma sintering was investigated. The experimental results show that the grain growth of SiC is inhibited with the increase of TiB2 content. When TiB2 content is 20 vol%, TiB2 promotes the decomposition of SiC into Si, which is located in the grain boundaries of SiC and TiB2 to reduce mechanical properties of composite ceramics. SiC-15 vo l%TiB2 composite ceramics have the preferable comprehensive mechanical properties with relative density, Vickers hardness, bending strength and fracture toughness of 98.8%, 27.2 GPa, 431 MPa and 5.24 MPa • m1/2, respectively. [ABSTRACT FROM AUTHOR]

Ceramic cubic boron nitride (CBN) wheel is widely used in grinding field for its superior grinding performance. The random grain orientation of CBN grinding wheel with ceramic bond affects its grinding performance to a certain extent. In this paper, magnetically controlled ceramic CBN grinding wheel was prepared by magnetic field and sintering process. In order to improve the magnetic conductivity of the abrasive grains, nickel-plated CBN was used to replace the abrasive particles. It was found that the direction of the abrasive particles could be effectively controlled by adjusting the strength and properties of the magnetic field, so that the abrasive particles presented a chain distribution under the magnetic field. The experimental results showed that the nickel-plated CBN abrasive grains have good orientation and chain distribution in the bond power by using alternating magnetic field. Finally, experiments were carried out to study the grinding of GH4169 with magnetically controlled ceramic CBN grinding wheel, and the experimental results were compared with common ceramic CBN grinding wheel. It was confirmed that the grinding temperature and grinding force of GH4169 with magnetically controlled ceramic CBN grinding wheel were slightly lower than that of common grinding wheel, and the grinding surface quality is better than that of ordinary grinding wheel. In this paper, the method of preparing ceramic CBN grinding wheel with controllable grain orientation was established, and the system of evaluating the grinding wheel performance was constructed. It enriched the preparation process of ceramic bond CBN grinding wheel, and would have important significance for further expanding the application of ceramic CBN grinding wheel. [ABSTRACT FROM AUTHOR]

In this paper, the traditional solid-phase reaction sintering process was used to synthesize Ca1-xMgxV2O6 (x = 0.03, 0.06, 0.09, 0.12) ceramics under low-temperature conditions. The effects of partial replacement of Ca2+ by Mg2+ on the A-site on the crystalline type, sintering temperature, microstructure, densification, and microwave dielectric performances of Ca1-xMgxV2O6 ceramic were studied. The only crystalline phase of CaV2O6 was observed in the ceramics. The sintering densification and dielectric performances of the Ca1-xMgxV2O6 ceramic show a trend of first increasing and then decreasing with the increase of Mg2+ content. The addition of Mg ions can effectively increase the Q × f value of the Ca1-xMgxV2O6 ceramics but cannot improve the τf value. The Ca0.91Mg0.09V2O6 ceramic sintered at 725°C displayed good microwave dielectric performances: εr = 10.41, Q × f = 68524 GHz, and τf = − 36.8 ppm/°C. The good dielectric properties of this ceramic can meet the development needs of 5G communication technologies. [ABSTRACT FROM AUTHOR]

The paper analyzes the influence of hard and soft admixture on the functional properties of multiferroic ceramic composites. Two composite materials via solid-state reaction route were obtained. PZT-type materials (with hard or soft admixture) were selected as the ferroelectric component (90%), and nickel–zinc ferrite as the magnetic component (10%). The influence of the doping type (soft and hard admixture of the ferroelectric composite component) on multiferroic composites' dielectric, ferroelectric, electromechanical, magnetic, and magnetoelectric properties were analyzed. Microstructural studies revealed the microstructure of composites with the correct distribution of the magnetic component in the ferroelectric matrix, suitable for maintaining both the ferroelectric and magnetic properties of composite materials. Research has shown that using a ferroelectric component as the PZT (from the morphotropic region and doped with the ferroelectrically soft niobium admixture) shows many advantages, positively influencing the functional properties of the multiferroic composite. It ensures effective polarization of the composite sample, obtaining a high magnetoelectric effect, which is required in sensors or magnetoelectric converters. PZT with a hard admixture shows higher stability of physical parameters, but its characteristic property also hinders the effective polarization of the composite sample. [ABSTRACT FROM AUTHOR]

This paper reports the mechanical properties of graded macroporous β-Ca3(PO4)2-based ceramic materials produced by stereolithographic 3D printing. We demonstrate the feasibility of using photocurable emulsions for the preparation of ceramic materials with porosity above 80% and controlling the pore size distribution. Graded-porosity ceramic materials with tailored pore size are produced using 3D printing of photocurable tricalcium phosphate-based emulsions. We examine the effect of emulsifier content on the average pore size in ceramic scaffolds with tailored architecture and the effects of porosity, average pore size, and 3D architecture on the strength characteristics of the macroporous ceramic materials. [ABSTRACT FROM AUTHOR]

This research evaluates the potentials of argillite quarry waste (AQW) as raw material in ceramics and other industrial applications based on traditional firing techniques. In this context, the AQW samples were first characterized by mineralogical (X-ray diffraction, XRD), chemical (X-ray fluorescence) and physical (grain size distribution and Atterberg limits) analysis. From the results, AQWs composed predominately of clayey-silt with medium to high plasticity. The XRD revealed predominance of clay minerals (illite-chlorite-vermiculite) with high contents of quartz and variable percentages of carbonate and feldspar. The oxides were dominated by SiO2 and Al2O3, low contents of ferromagnesian elements with considerable amounts of alkali and alkali earth elements. The CaO concentrations are high and relate to carbonate contents. The feldspar contents and proportions of alkali and alkali earth elements revealed their potential as stating materials for earthenware production. Empirical assessments using compositional ternary and Winkler diagrams revealed their acceptable level in ceramic applications. To evaluate firing behaviors, the AQW samples were prepared and fired in the range of 800 to 1000°C and technological properties (linear shrinkage LS, weight loss WL, water absorption WA, bulk density and flexural strength FS) were determined. Statistical approach was employed with focus on accuracy and reliability of the data. At 800°C and above, results revealed an increase in LS, WL and FS with decrease in WA. The levels of performance of technological properties of the AQW are considered marginal except with SiO2 contents reduction by 5–10% and with the addition of degreasers. The AQW met the most requirements for grade I, II and III ceramic raw material and other industrial applications such as filler for paper, rubber, plastic and paint industries as described in Indian standard specification. To achieve excellent performance in ceramics and other industrial applications, AQW requires beneficiations. [ABSTRACT FROM AUTHOR]

The cost of manufacturing a structural ceramic component is a direct function of production quantity. Small-quantity production, such as prototypes manufactured by conventional methods, leads to long production times and high unit costs. The advent of fused filament fabrication of ceramic (FFFC) technology has created an opportunity to reduce lead time and cost and produce complex-shaped bodies with tailored sized and controlled porosity in small-quantity production runs, which is an advantage over traditional methods of fabrication of ceramic products. In this work, we propose to study the feasibility of manufacturing a low-cost composite filament, for FFFC processing, based on micrometric alumina (Al2O3) powder and polylactic acid (PLA) polymer as a binder system without any additive. Three compositions with the ceramic-to-polymer ratios (by volume) were considered: 70% Al2O3/30% PLA, 60% Al2O3/40% PLA, and 50% Al2O3/50% PLA. For that, the customized technological chain is adapted. It consists of four principal steps: (i) grinding in a ball mill and drying the raw powders; (ii) extrusion into ceramic-polymer filament; (iii) printing of ceramic-polymer samples; and (iv) thermal debinding and sintering samples to obtain the ceramic product. The physical, microstructural, and mechanical properties of raw materials, composite filament, and green and sintering samples are investigated and the optimal composition is chosen dependent on both homogeneous repartition of the Al2O3 powder and the printability of filament. The 3D sintered material obtained by 60% Al2O3/40% PLA composite filament shows the best flexural strength value of 332 ± 21 MPa with a relative density of ~ 91%, which may be sufficient for several technical applications. Note that the 60% Al2O3/40% PLA filament composite can easily be used to print a complex geometry using a standard nozzle of 0.4 up to 0.8 and does not show signs of brittleness during the printing process allowing it to become a promising material for the FFFC process. Based on the results of this paper and previous studies, FFFC technology can be a technically feasible and economically viable process for manufacturing ceramic components under certain conditions. [ABSTRACT FROM AUTHOR]

Low-permittivity microwave dielectric ceramics could improve the transmission rate of devices. It is important to explore low-permittivity materials with excellent performances. In this paper, a low-permittivity microwave dielectric ceramic Na2Ba6Si4O15 (NBSO) was prepared by a solid-state reaction method. NBSO ceramics belong to a monoclinic system (space group: P21/c). With the increase of sintering temperature, the bulk density and relative density of ceramics also increases. The Q × f is explained by analysis of the packing fraction of NBSO ceramics. When the sintering temperature was 975°C, the packing fraction of the NBSO ceramic reached the maximum values of 57.38%. At the same time, the Q × f value of NBSO reaches its maximum. In addition, the τƒ value is affected by bond valence. The NBSO ceramic has good microwave dielectric performances of εr = 8.81, Q × f = 26,346 GHz, τƒ = − 9.21 ppm/°C) and a low sintering temperature, indicating that it is a strong candidate in the field of low-temperature co-firing technology and has good application prospects in the field of mobile communication base stations. [ABSTRACT FROM AUTHOR]

Cultural heritage identity management is the most basic and important work in the process of cultural heritage protection. It is of great significance to provide a unique and identifiable digital identity for ancient ceramics. At present, the identification information of ancient ceramics is mainly composed of external visual characteristics, and there is no report on feature identification method that can reflect the properties of ancient ceramics. Audible sound signals not only have advantages in non-destructive testing, but also can be used as voiceprint information to identify, monitor and analyze ancient ceramics. In this paper, seven ancient ceramics and 12 similar modern ceramic cups are taken as research objects, and an acoustic identifier (AID) is constructed. We put forward a reliable acoustic identification method for ancient ceramics, and established a digital code of acoustic characteristics of ancient ceramics. The results show that audible sound waves can reflect the attribute information of ancient ceramics. Sufficient acoustic data combined with deep learning can not only accurately match the identity of ancient ceramics, but also detect the real-time identity information of ancient ceramics, and make a comparative analysis of its cracks and whether it has caused damage. This method can provide a variety of practical applications for audible signal feature recognition technology in the exhibition, protection, trading, recognition and safety management of ancient ceramics and other cultural relics. [ABSTRACT FROM AUTHOR]

This paper reports enhanced high-temperature piezoelectric properties of Bi(Zn0.5Ti0.5)O3-modified BiFeO3-BaTiO3 (BF–BT-xBZT) ceramics prepared by two-step sintering method. The resultant ceramics show a symmetrical transition from a rhombohedral–pseudo-cubic (R-PC) phase coexistence to main PC phase with the increase of x, whose R-PC fraction (CR/CPC) is 53.3/46.7, 52.9/47.1, 50.2/49.8, 27.4/72.6, 15.3/84.7 when x = 0, 0.005, 0.01, 0.03, 0.05, respectively. The modification of BZT inhibits the grain growth, reduces the leakage current and gradually drives ferroelectric to relaxor transition. Optimal piezoelectric properties: d33 = 193 pC N−1, Pr = 20.6 μC cm−2, TC = 503 °C and kp = 36% achieved at x = 0.01 composition, which is due to the synergistic effect of an appropriate CR/CPC ratio, improved insulation and good polarization performance. In addition, the depolarization temperature Td is close 280–312 °C, and the high-temperature d33 further increases to 286–347 pC N−1, which shows a good application prospect of lead-free piezoceramics at high temperature. Our work also confirms that the addition of (Zn0.5Ti0.5)3+ and two-step sintering method are an effective and convenient strategy to improve the high-temperature electrical performance of BiFeO3–BaTiO3 based lead-free ceramics. [ABSTRACT FROM AUTHOR]

This paper reports on the structural, optical and luminescence studies of Dy3+–Eu3+ co-doped glass ceramics that are obtained via thermal treatment method. The initial confirmation on glass ceramics with the formation of NaBSiO4 crystalline phase was made through XRD study. The FTIR study showed the vibrations of network formers (B2O3, SiO2) and other functional groups. The quantity of non-bridging oxygens (NBOs) are increased in the glass ceramics with increase in annealing temperature. The absorption spectra (UV–visible-NIR) showed the possible transitions of Dy3+ and Eu3+ ions in the glass ceramics. A red-shift in the absorption band-edge and reduction in the optical band gap values were obtained for glass ceramics owing to their heating temperatures. Photoluminescence studies showed the excitations of Dy3+ and Eu3+ ions under 575 nm and 613 nm emission wavelengths. The obtained NaBSiO4 crystalline phase in the glass ceramics has enhanced the luminescence intensity, and lifetimes of Dy3+ and Eu3+ ions compared to unheated precursor glass when excited under 350 nm and 393 nm. Color chromaticity diagram and correlated color temperature (CCT) values showed a shift in the color of light from warm white of precursor glass to neutral white of glass ceramics. The overall results justify the possibility of considering the Dy3+-Eu3+ co-doped glass ceramics as efficient materials for solid-state lighting applications like W-LEDs. [ABSTRACT FROM AUTHOR]

The use of refrigeration technology is widespread in national security, industrial and agricultural production, biomedicine, and everyday life. High efficiency, environmental friendliness, and low cost make solid-state refrigeration based on electrocaloric effect (ECE) a promising refrigeration technology. Lead-free ferroelectric ceramics (1–x)Ba(Zr0.2Ti0.8)O3–x(Ba0.7Ca0.3)TiO3 (BZT–BCT) are promising materials for electrocaloric refrigeration in the field. In this paper, Sm-doped 0.5BZT–0.5BCT ceramic was fabricated by the conventional solid-state reaction method. The effect of Sm-doping contents (0, 1.0, 2.0, 2.5, and 3.0 mol.%) on the phase structures, dielectric properties, ferroelectricity, and electrocaloric properties of 0.5BZT–0.5BCT ceramics was systematically examined. The results indicate that all ceramics have a pure perovskite structure with no other secondary phase available. High relative densities are observed in all lead-free ferroelectric ceramics and all of the samples show transgranular fracture with no clear grain boundaries seen. The ceramics' ferroelectric hysteresis loops become thinner as the Sm doping content increases. At that, remanent polarization Pr decreases, indicating that more polar nanoregions (PNRs) are formed in BZT–BCT lead-free ceramics through Sm doping. The increase in Sm doping content resulted in a change in the dielectric permittivity and electrocaloric temperature that first increased and then decreased. The maximum dielectric permittivity is 5,518 when the doping content of Sm is 2.5 mol.% and the maximum electrocaloric temperature change ΔTmax of 0.109 K at 4 kV/mm was obtained when Sm doping content was 2 mol.%. The results show that an appropriate Sm doping is favorable for improving the dielectric, ferroelectric, and electrothermal properties of lead-free ceramics 0.5BZT–0.5BCT. [ABSTRACT FROM AUTHOR]

The corrosion resistance of float glass has been investigated in the course of climatic tests. It is shown that the main surface defects of tempered glass are leaching and “burnt-on paper and sulfurous film.” The properties of various interleaving materials used in the domestic industry are studied. The corrosion resistance of tempered glass depends on the surface of the initial glass and the properties of the interleaving material used for packing the initial as well as the tempered glass. [ABSTRACT FROM AUTHOR]

Through the second millennium BC, Bronze Age communities of Southern Italy have shown a remarkable degree of resilience in coping with changes in both macro-trends of cultural interaction and the landscape. In this paper, we will examine long-term processes of adaptation to shifting historical and environmental conditions from the vantage point of the impasto ware production at the site of Roca Vecchia (Melendugno-Lecce, IT), one of the main hubs of interaction for the Bronze Age of the Central Mediterranean. Sixty-eight ceramic individuals coming from the Middle to the Final Bronze Age levels and seven soil deposits from the site surroundings were analysed by petrography and fifteen were selected for SEM–EDX examination. We explore how changes in the complex history of the settlement and the surrounding landscape are matched in technological choices operated by the community of practice responsible for producing impasto pottery at Roca, in a moment when the long-range connection with the Aegean world was at its historical peak. [ABSTRACT FROM AUTHOR]

The paper focuses on the synthesis of MgAl2O4:Eu3+ and MgAlGaO4:Eu3+ spinel ceramics using radiation synthesis. It is shown how the average particle size and the particle size distribution in the initial synthetic oxide powders affect the synthesis process. Luminescence properties of the synthesized spinel ceramics are studied and analyzed herein. Luminescent properties of Eu3+ ions are clearly observed in the synthesized spinel ceramics. [ABSTRACT FROM AUTHOR]

Increasing porosity is one of the most direct ways to improve the thermal insulation and dielectric properties of materials. Until now, many wet methods for preparing Si3N4 ceramic foams usually face the problems of complex rheology, long period, and expensive cost, and the reported pore sizes of Si3N4 ceramic foams are typically micron-grade, resulting in a lack of competitiveness in thermal insulation and wave-transparent applications. In this paper, the Si3N4@SiO2 ceramic foams were prepared using an efficient dry-method, which combined three processes of low temperature chemical vapor deposition (LTCVD), template, and isostatic pressing. The method has the advantages of simple operation and short preparation period, and can realize near-net size molding and mass production. In addition, the evolution mechanisms of honeycomb microstructure and composition of Si3N4@SiO2 ceramic foam during sintering were studied by chemical reaction thermodynamics. The as-prepared Si3N4@SiO2 ceramic foam possesses low density (0.377 g·cm−3), high compressive strength (7.5 MPa), low thermal conductivity (0.0808 W·m−1·K−1), and excellent dielectric properties (ε < 1.32, tan δ < 0.009) in the frequency range of 8–18 GHz, and its maximum working temperature in air can reach up to 1100 °C. It will be recommended to be applied in the interlayer of Si3N4 ceramic radome to improve its thermal insulation and electromagnetic wave transparency performances. [ABSTRACT FROM AUTHOR]

This paper deals with the evolution of thermal residual stress (TRS) in Ceramic Matrix Composites (CMC) with environmental barrier coating (EBC) for aeroengine applications. In particular, in hot section component applications, where the durability requirement is of primary concern, CMC/EBC materials seem to be the most fascinating solution for effective and performant design. In this work, a numerical analysis has been conducted to study the effect of TRS on the damage mechanism in the 2.5D woven CMC coated with EBC. To figure out the heterogeneous and stochastic evolution of TRS in the coatings and substrate, a micromechanical finite element model of the composites containing the coatings was established based on the concept of representative volume elements. Especially, the variation of microstructure characteristics and constituents properties were taken into account in the micromechanical model. A series of simulations were performed to investigate the evolution of TRS during the cooling process after preparation and the thermo-mechanical loading process. Then, the thermal stress in coatings and substrate was calculated, and the influence mechanism of TRS on the failure was analyzed by comparison. The driven mechanism of the delamination crack and vertical crack was discussed based on the TRS results with uncertain characteristics. Based on this, uncertainty quantification can be performed to predict the durability life of the CMC/EBC system. [ABSTRACT FROM AUTHOR]

This paper offers an analysis of a group of glazed ceramics that comes from El Tolmo de Minateda site and have been dated in the second half of the ninth century and beginning of the tenth century, before the proclamation of the Umayyad Caliphate by Abderraman III (929 CE). Three technological groups have been distinguished: transparent glazes of one or two colours, transparent polychrome glazes (represented by two pieces) and opaque polychrome glazes (represented by two ceramics) studied by SEM-EDS analysis. After the study, different al-Andalus glaze workshops have been identified as providers of glazed ware to El Tolmo de Minateda site. The initial hypothesis was that the ware consumed in El Tolmo was manufactured in Pechina, the closest early production centre. However, after the archaeometric analysis, it has been discarded, and all the indications of this study seem to point to Córdoba as a significant supplier. The data of this study provides a new perspective on how the internal regional distribution and marketing of goods took place in Al-Andalus during the late Emiral period (c. 875–929 CE), a subject that has yet to be explored. [ABSTRACT FROM AUTHOR]

Abrasive water jet (AWJ) machining technology as a cold processing technology has the advantages of no thermal deformation, no thermal damage, and high processing flexibility. There are many researches in the field of ceramic plate processing, but little research has been done on the processing of irregular parts such as ceramic tubes. This paper presented the first proposal of using AWJ cutting zirconia ceramic tubes. The flow field characteristics of AWJ eroding tubes were analyzed by simulation, and the cutting characteristics of AWJ in two modes of radial cutting and axial cutting were studied. On this basis, the effects of jet pressure and traverse speed on kerf depth and morphology were analyzed, and the cutting mechanism of ceramic tubes by AWJ was given. The results show that the kerf depth increases with the increase of jet pressure and the decrease of traverse speed. In radial cutting mode, there is a difference in the kerf morphology between the entry and exit zone. Due to the real standoff distance and the change of processing conditions, the taper of the upper and lower kerf varied considerably in axial cutting mode. In addition, due to the influence of the vortex, a clear smooth transition zone appeared at the top of the lower kerf. In axial cutting mode, when the standoff distance is 2 mm, the jet pressure is 220 MPa, and the traverse speed is lower than 80 mm/min, both the upper and lower layers of the workpiece can be removed. [ABSTRACT FROM AUTHOR]

The focus of this paper is on fabrication of ceramic materials consisting of the anorthite phase synthesized from secondary materials, such as blast furnace sludge. It is found that the formation of the anorthite phase occurs when the CaO content is 6.29 wt.%. Physicochemical investigations show that major phases of ceramic materials are anorthite, wollastonite, and quartz. The synthesized ceramic materials containing the anorthite phase based on 10 to 30 wt.% of blast furnace sludge quantity, possess the following physical and mechanical properties: 38.2 to 33.4 MPa compressive strength, 2030 to 1990 kg/m3 density, and 9.4 to 10.2% water absorption. The structure of the ceramic material with the anorthite phase represents octahedral crystals of anorthite ranging in size from 3 to 10 μm, which agglomerate with wollastonite and quartz crystals and create the frame structure in the ceramic matrix improving the performance of products produced therefrom. [ABSTRACT FROM AUTHOR]

Mixing in extrusion is a vital part of achieving consistent and high-quality extrudates, with residence time being an elucidative measure of the mixing performance. Recent studies around numerical modeling of residence time distributions in single-screw extruders appear to consider flooded extruders mainly. This paper introduces a new and general CFD model to characterize the extruder fill length and residence time distribution for a viscoplastic ceramic material in a starve-fed extruder, including free surface tracking. The CFD model simulates a pulse-injection test, where a fluid parcel is injected at the inlet, with subsequent outlet concentration measured over time. The study includes material characterization and model validation based on laboratory tests. Results quantify the impact of accounting for the partially filled extruder instead of assuming it to be flooded, addressing the potential error when only considering simple analytical approximations to calculate system average residence times. Results further show the ability to fit simulation results to more simple analytical models. This underlines the importance of including the entire extrusion system and forming the basis for further work toward enabling real-time model predictions in starve-fed extrusion systems. [ABSTRACT FROM AUTHOR]

The effects of sintering temperature on the structural, dielectric, and ferroelectric properties of lead-free Ba0.96Nd0.02Na0.02TiO3 ceramics fabricated via a conventional solid-state reaction process are discussed in this paper. Sintered temperatures for the ceramics were 1200 °C, 1250 °C, 1300 °C, and 1350 °C. All samples comprise a single-phase tetragonal structure, according to XRD, Rietveld refinement, and Raman spectra. The density of electrons Equivalence maps was visible on Fourier maps. As the sintering temperature increases from 1200 to 1300 °C, the grain size increases from 4.64 to 9.84 µm. The correlation between structural, morphological, dielectric, and ferroelectric properties is detailed. The temperature dependency of the dielectric constant has been studied at three different frequencies in temperatures ranging from 30 to 200 °C. At 1300 °C, the Ba0.96Nd0.02Na0.02TiO3 ceramic achieves an optimum dielectric constant of 1054 and a dielectric loss of 0.012. Furthermore, at 1300 °C, this sintered material performs excellent ferroelectric remnant polarization of 8.05 µC.cm−2 and a coercive field of 20.87 kV.cm−1. Interestingly, the loss tangent at different frequencies for 1300 °C sintered samples was less than 0.1 over the entire temperature range, indicating that this sample is suitable for Multilayer Ceramic Capacitors (MLCCs) used in high-temperature applications. [ABSTRACT FROM AUTHOR]

The paper studies the structure kinetics of porous zirconia ceramics sintered at 1600°C with an isothermal holding from 10 to 600 minutes. The key research method is the assessment of the fractal dimension value of the fracture surface as an integral morphological characteristics. It is shown that an introduction of the organic pore-forming particles into the initial ceramic powder leads to the formation of bimodal porosity. The changes in the size of macro- and micropores during sintering are determined from the bulk and grain-boundary diffusion. The fractal dimension evolution reflects the entire complex of changes in the microstructure, including grains and pores, which determines the strength of the studied ceramics and makes it possible to estimate the stages of solid-state sintering. [ABSTRACT FROM AUTHOR]

Industrial alumina ceramics require high surface accuracy when assembled to critical components of devices, for which high-quality milling has become an integral process. To achieve high-quality milling of alumina ceramics efficiently, this paper introduced a composite strategy based on the sequence of roughing and finishing via the femtosecond laser burst-mode. Firstly, the effects of laser parameters in the single-pulse mode such as energy fluence, spot overlap ratio, and scanning spacing on the milling quality and efficiency of alumina ceramics were investigated to provide a basis of the parameter selection for the subsequent composite strategy study. Then, the influence of the burst-mode on the optimization of the milling results was discussed, and the advantages of this mode over the single-pulse mode were revealed. Finally, a comparative investigation on the processing performance between the composite strategy and the single strategy was carried out. The results showed that milling the same structure, the roughness of the groove was reduced by 10.69% compared to the optimal processing results in a single process. At the same time, the processing efficiency was maximized with an increase of 49.91%. [ABSTRACT FROM AUTHOR]

Silicon carbide fiber-reinforced silicon carbide matrix composites have attracted attention due to superior properties, such as low density, high strength, and high-temperature resistance. However, it often faces severe tool wear during cutting, with the fibers and matrix material being of high hardness and brittleness, which has an inevitable effect on the engineering application of this kind of material. In this paper, wear volume VW is used to evaluate the tool wear through solid modeling and parameter measurement based on the tool wear topography in turning of SiCf/SiC ceramic matrix composites. Conventional turning (CT), ultrasonic vibration-assisted turning (UVAT), and ultrasonic vibration-assisted turning with water cooling (W-UVAT) experiments are carried out using CBN, PCD, and PDC tools to investigate and analyze the cutting performance. In the meantime, the tool wear mechanism and form are studied based on the analysis of ultrasonic vibration on tool wear, the geometric position of wear, accumulation of cutting workpiece powders, and tool wear curve. Experimental results found that the PDC tool obtains the best cutting performance, which is more suitable for turning silicon carbide fiber-reinforced silicon carbide matrix composites. Within the experimental parameters, with the increased ultrasonic amplitude A, VW decreases first and then increases, reaching a minimum at A which is 3 µm. The main wear mechanism of the PDC tool is abrasive wear, and the primary wear form is the spalling of polycrystalline diamond abrasive grains. [ABSTRACT FROM AUTHOR]

MO-ZrO2-Ta2O5 (M = Zn, Co) ceramics were prepared by solid-phase reaction method. Thermo-gravimetric-differential thermal behavior, crystal structure, and microwave dielectric properties of ZnO-ZrO2-Ta2O5 and CoO-ZrO2-Ta2O5 ceramics were compared in this paper. Both of them exhibited monoclinic wolframite structure. Densest microstructures with uniform grains were obtained at 1400°C and 1425°C in the cases of M = Zn and Co, respectively. ZnO-ZrO2-Ta2O5 and CoO-ZrO2-Ta2O5 exhibited comparable εr ~ 20.26 and 24.30, while the former had Q × f ~ 60, 983 GHz and the latter had Q × f ~ 95,300 GHz. The grain growth exponent and activation energy obtained from the phenomenological kinetic equation indicated the growth process of ceramics. The grain growth of Zn-based ceramic was dominated by interfacial reactions and lattice diffusion. For the other one, the grain growth mechanisms were grain boundary diffusion and lattice diffusion at high temperatures. The grain growth progress of them both affected by lattice diffusion. The growth process of ZnO-ZrO2-Ta2O5 ceramics was faster than that of CoO-ZrO2-Ta2O5 ceramic. However, the grains were overgrown and grew slowly at 1425°C and 1450°C, which was caused by the excessive high temperature. [ABSTRACT FROM AUTHOR]