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The desirable characteristics of Ba_6-3xNd_8+2xTi₁₈O₅₄ include high dielectric constant, low loss tangent, and high quality factor developed a new field for electronic applications. The microwave dielectric properties of Ba_6-3xNd_8+2xTi₁₈O₅₄, with x = 0.15 ceramics at different sintering temperatures (600–1300°C) were investigated. The phenomenon of polarization produced by the applied electric field was studied. The dielectric properties with respect to frequency from 1 MHz to 1.5 GHz were measured using Impedance Analyzer, and the results were compared and analyzed. The highest dielectric permittivity and lowest loss factor were defined among the samples. The complex dielectric modulus was evaluated from the measured parameters of dielectric measurement in the same frequency range, and used to differentiate the contribution of grain and grain boundary.

Lead–free Sr${}_{1-x}$Ca_xTiO₃ ($x=0,0.4$) ceramics were synthesized via a solid state reaction technique at room temperature. The effects of ionic substitutions in A-sites between strontium and calcium on the structural and dielectric properties were investigated. XRD technique was used to identify the crystal structure and to demonstrate the phase purity. SEM observations have shown homogeneous morphologies for all samples. Dielectric measurements were investigated for a wide range of frequency (100Hz–1GHz) and temperature (25${}^{\circ }$C–250${}^{\circ }$C). Strontium substitution by calcium has not only led to a decrease in the dielectric permittivity value, but also to the loss tangent value by a considerable factor. Interesting values of the quality factor and the quite constant value ${\epsilon }^{\prime }\sim 200$ in extended frequency and temperature ranges show that SCT ceramic could be a real candidate for the development of monolithic ceramic capacitors dedicated to high-frequency lead-free components and/or to extremely high-temperature environments.

In the present work, comparative study of the dielectric behavior of Mn_0.4Zn_0.6Fe₂O₄ ferrite synthesized with and without H₂O₂ (hydrogen peroxide) has been presented. The dc resistivity has been improved by the citrate precursor method as compared to the ceramic method, and it is further improved by the addition of H₂O₂, which acts as a strong oxidizing agent. We have shown by means of X-ray diffraction that the resulting ferrite is made up of nanocrystallites and the average size of these nanocrystallites–calculated by Scherrer's formula–depends on the polarizer. The average particle size was found to be ~70 nm with H₂O₂ and ~88 nm without H₂O₂. The particle size is further confirmed by scanning electron microscopy. Both the results are found to be in good agreement. The decrease in dielectric constant and dielectric loss factor by addition of oxidizing agent is justified by inverse proportionality between the resistivity and dielectric constant. Possible mechanisms contributing to these processes have been discussed.

The friction and wear of silicon nitride (Si₃N₄) against silicon nitride (Si₃N₄) and zirconia (Y–TZP) and chilled cast iron and Alumina sliding under dry friction at room temperature conditions were investigated with pin-on-disk tribometer at sliding speed of 0.56ms^-1 and normal load of 50N, 80N, respectively. Based on the variety regulation of the wear maps, the wear mechanisms of the two couples were analyzed. Get the result of friction coefficient and maps of wear Rate of the Pin and the Disk. The results of comparing this couple is Si₃N₄/ chilled cast iron < Si₃N₄/ ZrO₂< Si₃N₄/ Si₃N₄< Si₃N₄/ Al₂O₃.

The use of silicon-based ceramics and composites as combustor liners and turbine vanes provides the potential of improving next-generation turbine engine performance, through lower emissions and higher cycle efficiency, relative to today's use of super alloy hot-section components. As a series of research for FOD resistant, a particle erosion wear test was carried out for continuous Pre-SiC fiber-reinforced SiC matrix composites with a new concept of lab. scale fabrication by LPS process. The result shows that aperture (some form of porosity) between fiber and interface has a deleterious effect on erosion resistance. Aperture along the fiber interfaces consequently causes a severe wear in the form of fiber detachment. Wear rate increase proportional as contents of open porosity increases. For nearly full dense composite materials of about 0.5 % porosity, are about 200 % more wear-resistant than about 5 % porous composites. Grain growth and consolidate condition of matrix which directly affects to FOD resistant are also discussed.

The drilling of film cooling holes on gas turbine blades made out of ceramic-coated superalloy improves the efficiency of the gas turbine and prolongs the life of the turbine blade. The purpose of this study was to investigate the effects of different stand-off distances (SODs) on abrasive water jet (AWJ)-pierced holes, in which the machining time, entry and exit hole diameters, overcut, hole taper, and surface morphology were studied. In this study, the water jet pressure (WJP) of 275MPa, piercing angle of $90^{\circ }$, dwell time of 0.2s, and abrasive flow rates (AFRs) of 350g/min and 400g/min were considered for the AWJ piercing operations. The entry and exit hole diameters and overcut linearly increased with an increase of SOD with different abrasive flow rates. And hole taper was observed at the coating and substrate sections in which it decreased with an increase of SOD up to 2mm, and a further increase of SOD increased the hole taper. Besides, the drilled holes were found to have an absence of delamination, cracks, and thermal defects. It was also noted that there is a transformation from a brittle to a ductile mode of erosion that may occur in the high-erosion kinetic energy impact region in the YSZ material section. Based on the experimental results, it is confirmed that SOD of 2mm became an influencing factor in AWJ for piercing quality holes in the YSZ-coated superalloy.

CaCu₃Ti₄O₁₂ (CCTO) ceramics which has perovskite structure gained considerable attention due to its giant permittivity. But it has high tan δ (0.1 at 1 kHz) at room temperature, which needs to be minimized to the level of practical applications. Hence, TeO₂ which is a good glass former has been deliberately added to CCTO nanoceramic (derived from the oxalate precursor route) to explore the possibility of reducing the dielectric loss while maintaining the high permittivity. The structural, morphological and dielectric properties of the pure CCTO and TeO₂ added ceramics were studied using X-ray diffraction, Scanning Electron Microscope along with Energy Dispersive X-ray Analysis (EDX), spectroscopy and Impedance analyzer. For the 2.0 wt.% TeO₂ added ceramics, there is a remarkable difference in the microstructural features as compared to that of pure CCTO ceramics. This sample exhibited permittivity values as high as 7387 at 10 KHz and low dielectric loss value of 0.037 at 10 kHz, which can be exploited for the high frequency capacitors application.

The polycrystalline ceramic Pb${}_{0.5}$Ba${}_{1.5}$BiVO₆ manifesting the complex double perovskite structure was tailored by the conventional solid state route at a moderate temperature. Qualitative phase analysis and formation of the ceramic were affirmed by XRD analysis. The X-ray powder diffraction pattern of the compound explored at room temperature affirms the single phase formation with double perovskite structure exhibiting rhombohedral phase. Microstructural analysis of the studied compound procured from the Scanning Electron Microscope (SEM) validates the formation of dense microstructures and nonuniformly distributed grains with minimal voids. Compositional analysis was shaped through the Electron Diffraction Spectroscopy (EDS) confirming the absence of contamination of any other metals apart from the mentioned ones. Dielectric (Cr and $tan\delta$) parameters of the compound were studied using the LCR analyzer at different temperatures and wide range of frequencies. The polarization and dielectric study affirms the presence of ferroelectricity in the material with transition temperature much above the room temperature. The tangent dielectric loss of this sample being almost minimal at room temperature attributes it to find applications in different grounds of electronics. Optical equities of the ceramic were further analyzed by the RAMAN, FTIR, UV–Vis and Photoluminescence spectroscopy.

The paper presents the results of a study of the microwave absorption properties of ceramic materials based on bismuth ferrite containing rare earth elements, as well as systems of solid solutions ($1-x$)BiFeO₃–xPbFe${}_{1/2}$Nb${}_{1/2}$O₃ in a wide range of component concentrations. The methodology for measuring and calculating the parameters of samples of the materials under study is described. The influence of structural and microstructural factors on the average and maximum level of microwave absorption of the materials under study in a wide frequency range is analyzed. A comparison of the microwave absorbing properties of these materials with industrial absorbers has been carried out, and prospects for application in microwave technology have been shown.

Ceramic has a great broad application in high-temperature environment due to its favorable mechanical, antioxidant and corrosion resistance properties. However, it tends to exhibit severe crack or fail under thermal shock resulting from its inherent brittleness. Microstructure property is a vital factor and plays a critical role in influencing thermal shock property of ceramic. The present study experimentally tested and characterized thermal-shock crack and residual strength of ceramic under different quench temperature, while two kinds of alumina ceramics with different grain size are employed. A two-dimensional (2D) numerical model based on statistical mesoscopic damage mechanics is introduced to depict the micro-crack propagation of ceramic sheet under water quenching. The effects of grain size on critical thermal shock temperature, crack characteristics and residual strength are studied. And the microscopic mechanism of the influence of grain size on thermal shock resistance of ceramic is discussed based on the crack propagation path obtained from experimental and simulation results. The qualitative effect and evolution change of grain size on thermal shock property of alumina ceramic will be summarized.

Ceramic bearing surfaces have been used over the last 25 years as a clinical solution to the polyethylene wear debris which has been attributed as the major cause of aseptic loosening in total hip arthroplasties. Research has continued over the last 15 years to transpose the technology from the hip to the knee. Monolithic ceramic knee devices have been implanted, mainly in Japan, but the problem of the femoral fixation has remained. The improvement in the polyethylene materials, coupled with the more congruent knee designs, has focused the major issue to wear particle generation as opposed to fatigue or delamination.

The focus of the Brite EuRam project “Advanced Metal to Ceramic Joining Techniques To Optimise low-friction knee prostheses” was to address the issue of fixation in conjunction with the optimum ceramic bearing surface. This was achieved by the development of a biocompatible active alloy braze for joining medical grade Y-TZP zirconia to titanium alloy. Through optimised chemistry and processing conditions a high strength active alloy braze joint was obtained that satisfied all biological and mechanical requirements.

Extensive Finite Element analysis, mechanical, fatigue, wear and compression strength testing were performed to validate the new concept.