Ceramic Compounds Research Articles

A newly developed YbFeO3-YbCrO3-YbMnO3 pseudo-ternary phase diagram: Crystal structure, optical, and dielectric properties in seven selected orthorhombic ternary solid solution compounds.

We construct a YbFeO3-YbCrO3-YbMnO3 pseudo-ternary phase diagram that illustrates the different equilibrium phases regions where orthorhombic, hexagonal, and orthorhombic, and hexagonal phases at room temperature coexist. Thirty-three Yb:Fe:Cr:Mn molar ratio compositions were designed using solid-state reactions. They were characterized by X-ray diffraction. Poor miscibility of the hexagonal single phase in a small region of the YbMnO3-YbFeO3 pseudo-binary phase was found. The maximum miscibility of Mn into the orthorhombic phase is found in the YbFe50Cr25Mn25O3, YbFe375Cr375Mn25O3, and YbFe25Cr50Mn25O3 intermediate ternary ceramic compound. Beyond this concentration of Mn, the YbFeO3 - YbCrO3 - YbMnO3 pseudo-ternary system breaks down into mixing hexagonal and orthorhombic phases. Once the different phases were established; the crystalline structure, microstructure as well as optical and dielectric properties were investigated in seven selected compositions in the orthorhombic zone, where the total Fe – Cr and the partial Mn miscibility tunes the cell volume. SEM images reveal grains coalescence, indicating incipient fusion in the YbFeO3 sample. As Cr and Mn increase, the sign of incipient fusion and grain size decreases. The dielectric properties were evaluated as a function of temperature, and through these quantities it is found that the electrical conductivity increases for the intermediate ceramic compound. This fact agrees with the optic band gap, Eg, which decreases for these intermediate compounds. According to the dielectric study, we found that the decrease in the Eg is mainly associated with charge carriers polarons (∼0.20 - 0.25 eV) at low-temperature and oxygen vacancies (0.55 -0.61 eV) at high temperatures.

Boosting the efficiency of water-based intumescent coatings with fumed silica nanoparticles: A synergistic approach

This research looked into how well the water-based intumescent coating (WBIC) with fumed silica nanoparticles (FSNs) worked to keep steel parts safe from cellulose fire. The adhesion strength of the coatings was evaluated using the pull-off test according to ASTM D4541. Flame retardant performance was studied by a lab-scale simulated big panel test at 950 °C for 1 hour. Thermogravimetric analysis (TGA) and the UL94 test were used to study the thermal stability and burning characteristics of the WBIC. An FESEM, an X-ray diffraction (XRD), and a Fourier transform infrared spectroscopy (FTIR) analysis were used to fully characterize the residual chars of the optimized formulation and the control coating. Adhesion strength test results showed that adding 0.2 wt% of FSNs increased paint adhesion strength from 0 to 2 MPa and changed the failure mode from adhesive to cohesive. It was found that at the optimal FSNs content (0.2 wt% SiO2), the lowest steel backside temperature of 181℃ after 1 hour of fire testing was obtained. Adding fumed silica from 0.1 to 0.3 wt% has resulted in a reduction of the char layer's intumescent factor by 5.3–42.1 %. The SEM images indicated that fumed silica enhanced the formation of dense, crack-free char layers with small pore sizes. Thermogravimetric analysis revealed that intumescent coatings' thermal stability and residual weight increased with the addition of 0.2 wt% fumed silica. Additionally, the coating contained 0.2 wt% SiO2 passed the V0 rating in the UL94 vertical burning test. The XRD and FTIR tests also revealed that the leftover chars had rutile titanium oxide, aluminum metaphosphate, and titanium pyrophosphate in them. At high temperatures, these ceramic compounds exhibit thermal insulation performance, preventing heat and oxygen penetration into the char layer.

Regulating novel tunable green to red upconversion luminescence in Er3+/Yb3+ co-doped SrBi2Nb2O9 ferroelectric ceramic

A series of SrBi2-x-yNb2ErxYbyO9 (SBN) ferroelectric ceramics co-doped with Erbium and Ytterbium have been fabricated through solid-state approach, the formation of pure phase SrBi2Nb2O9 has been confirmed by XRD spectra corresponding to orthorhombic geometry having phase group A21am. The lattice parameters and volume of the unit cell increase with the content of Yb3+. SEM study revealed the randomly oriented plate-like structure of SBN having average particle sizes ranging from 0.9 μm to 2.23 μm. The FTIR characteristic bands are found at wavenumber 602 cm−1 and 812 cm−1. In Photoluminescence (PL) spectra, two green emission bands (524 nm and 549 nm) and one weak red band (660 nm) are acquired using a 488 nm excitation wavelength. The diffuse reflectance spectra (DRS) of ceramic compounds reveal that the values of band gap ranges from values 2.7–3.1eV. Two UCL bands are seen at wavelength 533 nm, and at wavelength 554 nm in the green part of the upconversion photoluminescence (UCL) spectra, and a single band observed at a wavelength of 672 nm in the red region upon excited by 980 nm laser. The green band dominates for initial concentration up to x = 0.03, y = 0.03 after which red emission dominates with increasing concentration of Yb3+. The dependence study of pump power on UCL emission intensity reveals that there are two photons are involved in UC emissions of green and red. The time decay analysis of SBN composition showed that the average decay time of Er3+ is 70μs and that of the co-doped system (Er3+/Yb3+) is 37 μs

Exploring the Properties, Synthesis, and Applications of Magnesium Aluminate Nanoparticles

Magnesium aluminate (MgAl2O4) is a synthetic ceramic compound, characterized by a spinel structure and comprised of magnesium oxide (MgO) and aluminum oxide (Al2O3). Magnesium aluminate is esteemed for its distinctive combination of thermal, mechanical, and optical characteristics, making its role remarkable for various applications. Hence this review, focuses mainly on magnesium aluminate nanoparticles, a subject that is gaining prominent attention in the current research scenario. There are several methods available for the synthesis of MgAl2O4 nanoparticles (MANPs), including sol-gel and co-precipitation techniques, along with those that incorporate green methodologies. The high melting point, substantial hardness, and excellent thermal shock resistance of the host material suggest that MANPs could hold a significant place in the field of nanotechnology. Numerous studies have demonstrated that the introduction of different ions into MANPs through doping effectively altered their characteristics, thereby improving their functional capabilities. Thus, this review gives a comprehensive examination of the properties of magnesium aluminate, the synthesis methods utilized, impacts of doping, and various applications of magnesium aluminate nanoparticles.

Crystal structure and magnetic properties of Fe doped BaTiO3 at morphotropic phase boundary

Ceramic compounds BaTi1-xFexO with x = 0–0.2 prepared by solid state reaction technique were studied using X-ray diffraction, Raman spectroscopy, and magnetometry methods focusing on the correlation between the structure and magnetic properties. Chemical doping with Fe ions leads to a concentration driven structural transformation from the single phase tetragonal (T-) structure to the hexagonal (H-) structure with a mixed structural state stable in the concentration range 0.06 <x ≤ 0.2. Increase in the Fe ions content causes a stabilization of weak ferromagnetic state driven by the exchange interactions Fe3+ – O – Fe3+ ions strongly dependent on the structural positions of the Fe ions. Increase of the dopant content above x = 0.08 leads to a decrease of the remnant magnetization which is mainly caused by a stabilization of Fe4+ ions as well as by the lattice defects associated with oxygen vacancies formed to keep electroneutrality of the compounds. The results of the structural and magnetization measurements allowed to itemize the type of exchange interactions between Fe ions residing different structural positions of the hexagonal lattice as well as to reveal structural instability of the T- and H- phases under ambient conditions and applied electric field which shows a possibility to control the structure and magnetic properties of the mixed compounds via external stimuli.

From LaCrO3 towards LaCr0.2Mn0.2Fe0.2Al0.2Ga0.2O3 high-entropy ceramic compound: Crystal structure, dielectric and magnetic properties

A group of five perovskite-type ceramic systems was designed by solid-state reaction, increasing the configurational entropy, ΔSconf at the B-site, going from low and medium to finally reaching a high-entropy system. Chemical elements, crystal structure, and microstructure characterization, as well as the dielectric and magnetic properties, are discussed from the single phase LaCrO3 towards a continuous equiatomic multicomponent LaCr0.2Mn0.2Fe0.2Al0.2Ga0.2O3 ceramic compounds. Through a combination of structural analysis and XPS spectroscopy study, it is found that not only the configurational entropy ∆Sconf term, but also the enthalpy of mixing, ΔHmix through of arising of the coexistence of mixed valence state, oxygen vacancies, and local octahedral distortions lead to the stabilization of the single phase in equimolar multicomponent perovskite systems. The arising of Cr3+/Cr6+ and Mn3+/Mn2+ mixed valence state drives the AC electric conductivity through the presence of two kinds of charge carriers, small polarons and oxygen vacancies in LCM, LCMF, LCMFA, and LCMFAG ceramic compounds. The occurrence of these two classes of charge carriers progressively increases the AC electric conductivity at room and high temperatures for each ceramic compound, being higher for the LCMFA entropy compound, making it a potential candidate for solid oxide fuel cell (SOFC) applications. As expected, the increases of compositional random cations display rich magnetic properties arising from competing magnetic interactions driven by the sublattice of Cr, Mn, and Fe magnetic ions. The resulting ΔSconf increase leads to a Griffith-like phase. The results also show that not only the ferromagnetic clusters of the LaMnO3 (AxFz) sublattice but also the weak ferromagnetism associated with the LaCrO3 (GxFz), and LaFeO3 (GxFz) sublattices play a predominant role in the formation of the Griffiths-like phase in the low, medium and high-entropy ceramic systems.

Electrochemical and structural properties of binder-free iron-based bifunctional catalyst for aqueous Zinc-Oxygen batteries

Global warming necessitates efficient new batteries, with Zn-O2 batteries standing out due to their high theoretical energy density, safety, and long cycle life, making them ideal for large-scale use. However, their industrial application faces challenges such as rapid energy density decline after initial cycles, limited cathode efficiency, and high overpotential between discharge and charge. This study focuses on synthesizing and characterizing ceramic iron compounds as catalysts for the cathode of Zn-O2 aqueous batteries. The findings revealed that obtained catalysts presented surface active areas beyond 220 m2/g after calcination at 800 °C, which removed organic templates. Various thermal treatments have been analysed to measure their impact on the final product. XRD, FTIR, and Raman spectroscopy confirmed sample nitridation, while SEM showed macro–meso-porosity. The electrochemical evaluation demonstrated a significant enhancement in the material's catalytic properties for ORR/OER in alkaline Zn-O2 batteries, surpassing 140 h of satable cyling with catalytic activity for ORR and OER. This improvement, coupled with optimized electrode design, resulted in a substantial increase in the batteries' operational life, achieving stable cycling for over 120 h.

Synthesis of biocompatible Ti-6Al-4V composite reinforced with ZrO2 and bioceramic produced by powder metallurgy: Morphological, structural, and biocompatibility analysis.

In this experimental study, the initial phase involved preparing composite structures with various mix ratios using the Ti-6Al-4V alloy, widely used in clinical applications, in conjunction with ZrO2 and hydroxyapatite (HA) synthesized via the precipitation method, employing powder metallurgy techniques. Subsequently, the microstructures of the resultant hybrid composite materials were imaged, and x-ray diffraction (XRD) phase analyses were conducted. In the final phase of the experimental work, tests were performed to determine the biocompatibility properties of the hybrid composites. For this purpose, cytotoxicity and genotoxicity assays were carried out. The tests and examinations revealed that structures compatible both morphologically and elementally were obtained with no phase transformations that could disrupt the structure. The incorporation of ZrO2 into the Ti-6Al-4V alloy was observed to enhance cell viability values. The value of 98.25 ± 0.42 obtained by adding 20% ZrO2 gave the highest cell viability result. The addition of HA into the hybrid structures further increased the cell viability values by approximately 10%. All viability values for both HA-added and HA-free groups were obtained above the 70% viability level defined in the standard. According to the genotoxicity test results, the highest cytokinesis-block proliferation index values were obtained as 1.666 and 0.620 in structures containing 20% ZrO2 and 10% ZrO2 + 10% HA, respectively. Remarkably, all fabricated composite and hybrid composite materials surpassed established biocompatibility standards and exhibited nontoxic and nongenotoxic properties. This comprehensive study contributes vital insights for future biomechanical and other in vitro and in vivo experiments, as it meticulously addresses fundamental characterization parameters crucial for medical device development. RESEARCH HIGHLIGHTS: Support of optimum doping rates ions on hybrid composites and concentrations. Development of uniform surface appearance and distributions/orientations of microcrystals on ceramic compounds Improvement of cell viability and desired increase in biocompatibility with the doping of HA.

Stabilization of durable tetragonal phase and barrier regions in y-123 ceramic systems with partial substitution mechanism

This study examines the impact of Tb and Zn doping on the Y-123 superconducting system by analyzing crack propagation mechanisms through Vickers microhardness measurements. The measurements are conducted at various application forces ranging from 0.245 N to 2.940 N. The microhardness measurements are used to determine the role of impurity addition on Vickers hardness, modulus of elasticity, brittleness index, fracture toughness, and yield strengths. It is found that impurity ions serving as strong barrier regions improve the surface residual compressive stress sites and interactivity between the adjacent layers. Similarly, the sensitivity to the external forces reduce significantly with the substitution mechanism due to the induced new slip systems and ionic bond formations. Accordingly, all the mechanical performance properties are recorded to increase significantly with the impurity ions. Especially, the replacement of Zn by Cu ions in the Y-123 matrix exhibits higher resistance to failure, mechanical strength, and stabilization of the durable tetragonal phase. Accordingly, Zn/Cu substitution in Y-123 ceramics paves the way for the applications of ceramic compounds in the fields of heavy-industrial technology and industrial power systems. All the ceramic materials also exhibit indentation size effect feature based on the recovery mechanism. Additionally, load-independent microhardness parameters are semi-empirically modeled by Meyer's law, Hays-Kendall, indentation-induced cracking, elastic–plastic deformation, and proportional sample resistance model for the first time. According to the comparisons, the IIC model is identified as the most suitable for interpreting the real microhardness results of newly produced Y-123 ceramic matrices.

Evolution of fundamental mechanical properties with aliovalent Co/Cu partial substitution and preparation method for Y-123 system

This study investigates the effect of aliovalent Co/Cu replacement and preparation method on fundamental mechanical performance features of YBa2Cu3−xCoxO7−δ (Y-123) ceramic system depending on the crack propagation mechanism by Vickers hardness measurements (Hv) and mechanical investigation models for the first time. All the findings are verified by the scanning electron microscopy (SEM) examinations. Besides, the electron-dispersive X-ray (EDX) technique verifies the successful substitution mechanism. Besides, the Vickers hardness parameters improve systematically with the increment in the Co/Cu partial substitution (serving as a barrier) level due to formation of operable slip systems, ionic bond formations, and decrement of stress-amplified strain fields. Moreover, the Y-123 ceramic produced by solid-state reaction method and molecular weight of 0.20% presents the densest and smoothest surface morphology with the largest particle distributions and well-linked cobblestone-like grains. On the other hand, the Y-123 ceramic compounds produced by the sol–gel method are more sensitive and responsive to the indentation test loads. All the findings are wholly supported by the mechanical performance properties, including the shear modulus, resilience, and degree of granularity. Furthermore, the mechanical models indicate that every compound prepared exhibits the untypical reverse indentation size effect (RISE). Additionally, the modeling studies display that the induced cracking (IIC) approach is found to be the most appropriate method to examine true Vickers hardness parameters in the plateau limit regions. All in all, this comprehensive study reports efficiently exploiting the process–structure–property relationships in Y-123 ceramic material design for physical science and mechanical application fields using the aliovalent partial substitution and preparation condition.

Precursor influence on the raman spectrum of KNNLiTaLa0.01 prepared by two different methods

This work presents a study of ceramics with the (K0.44Na0.52Li0.04)0.97La0.01Nb0.9Ta0.1O3 composition through their Raman spectra. In the previous studies [1], this particular composition has shown good permittivity and piezoelectric parameter values that justify a deeper investigation. Two sets of samples of these ceramic compounds were prepared using different methods. The first set was prepared using a classical solid-state reaction of oxides and carbonates, as described in Ref. 2. The second set was prepared using the NaNbO3 as a precursor. The Raman spectra of the samples obtained by the direct ceramic method consisted of 4 modes. In contrast, the spectra of the samples obtained using the precursor showed a shift of the wavenumber of the A1g(ν1) mode peak towards lower values and consisted of six modes with the appearance of two additional IR modes, F1u(ν3) and F2g(ν4). Notably, the use of the precursor preparation route led to important improvements resulting in a more straightforward method than that of Saito et al. [3].

Experimental investigation on the wear characteristics of TiC-Co composite coating deposited on AZ91D Mg alloy substrate by plasma transferred arc (PTA) welding process

Abstract In this investigation, a plasma transferred arc (PTA) cladding process was employed to deposit TiC-Co composite coatings on substrate of AZ91D magnesium (Mg) alloy. The morphology and phases of the recently produced composite coatings were examined using scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The microhardness and wear rate were evaluated by Vickers microhardness tester and pin-on-disc wear and friction test apparatus at the room temperature respectively. The results demonstrate that dense, uniform, and crack free coatings, with good metallurgical bonding to the AZ91D Mg alloy substrate were formed. The most of the phases present in composite coatings were TiC, Mg, CoTi, α-Co, AlCo, Al3Ti, and Co3C. The maximum average micro-hardness of TiC-Co composite coating was found to be about 1743 HV, which depends on the PTA currents. Whereas, average micro-hardness of the AZ91D Mg alloy substrate was 65 HV. This indicates that the coated layer produced increase in hardness about 27 times of substrate hardness. The cladding layer exhibited a wear rate of 4.94×10-8 g/N-m, whereas the wear rate of the AZ91D Mg alloy substrate was 58×10-8 g/N-m. This indicates that the wear resistance of cladding layer was 12 times higher as compared to AZ91D Mg alloy substrate. The enhanced micro-hardness and wear resistance of TiC-Co composite coating can be attributed due to the formation of ceramic and intermetallic compounds, unveiling its superiority over the AZ91D substrate.

Ca/Sn concentration-dependent enhancement of barium titanate ferroelectric performance: a dielectric and microstructural study

This work involved the synthesis of compositions of Ba0.95Ca0.05SnxTi1-xO3 (BCST) with varying amounts of Sn dopant (x = 0, 0.02, 0.04, 0.06, 0.08, and 0.1). A standard solid-state reaction approach was used to create all of the ceramic compounds. Each BCST composite’s microstructure, sintering, morphology, density, optical, and electrical characteristics were carefully examined, and the dielectric performance was optimized. In comparison to the unmodified composite, introducing varied amounts of Sn material into the BCST compound changed the crystal lattice vibrations and functional group locations. This result indicates that there are some variations in unit cell size, revealing that Sn+4 ions diffused effectively inside the lattice structure to produce BSCT composites. Further, SEM micrographs indicated proportionate changes in the homogenous structure and irregular forms as Sn concentration increased, as well as some variation in average grain size. As a consequence, by adding 0.08 mol% of Sn dopant, the crystallite size and average grain size were adjusted to 45.69 nm and 0.66 µm, respectively. Meanwhile, the 0.08-Sn specimen displayed a dielectric constant (Ɛ) with an optimum value of 5557 and a relative decrease in the Curie-Weiss constant. These results are attributed to the existence of various concentrations of Sn ions at the Ti-site of the BCT, which resulted in a compositionally disordered state. This disordered condition is essential for the production of dielectric compounds. Therefore, it is evident that modifying the amount of Sn doping added significantly enhanced the dielectric characteristics of the BCST composites created in this work. However, excessive Sn doping reduces the dielectric properties due to a reduction in tetragonal phase and an increase of disorders and charge fluctuations.Graphical

Beyond metals: theoretical discovery of semiconducting MAX phases and their potential application in thermoelectrics.

MAX phase is a family of ceramic compounds, typically known for their metallic properties. However, we show here that some of them may be narrow bandgap semiconductors. Using a series of first-principles calculations, we have investigated the electronic structures of 861 dynamically stable MAX phases. Notably, Sc2SC, Y2SC, Y2SeC, Sc3AuC2, and Y3AuC2 have been identified as semiconductors with band gaps ranging from 0.2 to 0.5 eV. Furthermore, we have assessed the thermodynamic stability of these systems by generating ternary phase diagrams utilizing evolutionary algorithm techniques. Their dynamic stabilities are confirmed by phonon calculations. Additionally, we have explored the potential thermoelectric efficiencies of these materials by combining Boltzmann transport theory with first-principles calculations. The relaxation times are estimated using scattering theory. The zT coefficients for the aforementioned systems fall within the range of 0.5 to 2.5 at temperatures spanning from 300 to 700 K, indicating their suitability for high-temperature thermoelectric applications.

Studies on structural, dielectric, and ferroelectric features of lanthanum modified complex Bismuth Nickel Titanate ceramic

Lanthanum substituted Bismuth Nickel Titanate (BNTO) ceramic, that is, (Bi 0.8La0.2)(Ni0.5Ti0.5)O3 (abbreviated as BLNTO 20) was successfully synthesised by solid-state reaction technique. The phase formation of the ceramic compound was confirmed by the X-ray diffraction study. The FESEM micrograph depicts the homogeneous spreading of the dissimilar size grains on the surface of the compound. The dielectric characteristics of ceramic were observed by computing the dielectric outcome in selected range of frequency and temperature. The frequency/temperature dependent conductivity plots of the ceramic compound satisfy the universal Jonscher’s power law. P-E Loop tracer was used to study the ferroelectric nature, which suggests the possibility of enhanced ferroelectric behaviour of the compound. Therefore, based on the enhanced ferroelectric features due to La doping ceramic compound may have promising performance for further electronic device application.

Direct Current Sputtering Deposition of the Metallic Ceramic Ti3SiC2 Thin Film with Improved Hydrophobicity and Reduced Surface Energy

Metallic ceramic compounds, such as Ti3SiC2, are innovative materials that combine the properties of metals and ceramics. However, most methods used in synthesizing these materials employ high deposition temperatures. Hence, in this work, Ti3SiC2 thin film was prepared and deposited on a steel sample without heating or biasing using a magnetized sheet plasma source. The synthesis was carried out by sputtering titanium, silicon, and graphite targets with Ar plasma at different deposition times of 60, 90, and 120 minutes. Energy dispersive X-ray (EDX) and X-ray diffraction (XRD) scans of the samples confirmed the synthesis of the desired compound. Moreover, the wettability and surface energy properties of the coated substrate were calculated by contact angle measurements. Results showed that as the deposition time increased, the coated substrate became more hydrophobic. Indeed, these findings show that Ti3SiC2 deposited steel substrate, with its increased hydrophobicity, is a potential self-cleaning coating for industrial tools.

Investigation and Evaluation of High-Temperature Encapsulation Materials for Power Module Applications

With the advent of ultra-wide bandgap (UWBG) semiconductor materials, such as Gallium Oxide (Ga2O3) and Aluminum Nitride (AlN), higher temperature and higher voltage operation of power devices is becoming realizable. However, conventional polymeric and organic encapsulant materials are typically limited to operating temperatures of 200 °C and below. In this work, six materials were identified and evaluated as candidates for use as encapsulants for operation and high-voltage insulation at and above 250 °C. High-temperature silicone gel was used as a reference material and was compared to five novel encapsulants including an epoxy resin, a hydro-set cement, two low melting point glass compounds, and a ceramic potting compound. Gas pycnometry was utilized to evaluate the voiding concentration to avoid partial discharge. Each material was then processed onto a direct-bonded-aluminum (DBA) substrate test coupon to evaluate compatibility with a commonly used metal-ceramic substrate and processability for use in a power module. The insulation capability of each material was evaluated by testing the partial discharge inception voltage (PDIV) across a 1mm gap etched in the substrate. The dielectric stability was then tested by soaking the materials in air at 250 °C for various intervals and observing the degradation of their PDIVs and appearances. The results of each test were compared, and conclusions were drawn about each material’s feasibility for use as a dielectric encapsulation material for a power module operating at temperatures exceeding 200 °C.

Structural and enhancement of electrical properties of BFO-LFO solid solution

To synthesizes the polycrystalline perovskite ceramic compounds (That is, (BiFeO3)1-x + (LaFeO3)x, having x = 0.0, 0.1, 0.2 and 0.3) (BFO-LFO), by using an elevated temperatures solid state reaction technique. Powder X-Ray diffraction (P-XRD) was employed for structural analysis to validate the creation of single phase materials and the phase structure of BFO-LFO changing from rhombohedral to tetragonal. The morphological characteristics of the surface of ceramic composite pellets were examined by using a scanning electron microscopy at the ambient temperature, which revealed a uniform arrangement of grains with very little porosity and varying sizes on the samples' surface. At various temperatures (25-500 °C), the frequency-temperature connection of dielectric and electric characteristics was studied utilizing dielectric and complex impedance spectroscopy. Both grains and grain boundaries have been demonstrated to have a substantial impact on the electrical sensitivity of the materials. All BFO-LFO samples exhibited a negative temperature coefficient of resistance.

Exhaust gas recirculation in a compression-ignition engine with nano coated Al2O3-TiO2 and ethanol fuel

Ethanol is a fuel that is sustainable, made from biomaterials, and oxygenated. It has the potential to lower the amount of particle emissions produced by diesel engines, as well as the amount of CO2 produced during its life cycle. Even though it was indicated by the exhaust gas recirculation (EGR) approach, the pistons, valves, and cylinder heads of the CI engine were coated in a ceramic compound composed of Al2O3 and TiO2. The exhaust gas recirculation (EGR) technology allows for the cooling and redirection of exhaust gas that has been removed from the cylinders of the exhaust system. Following the application of thermal coating to the piston, the performance of the engine's combustion system improved. The elimination of carbon monoxide, hydrocarbons, and smoke is a direct result of the addition of ethanol. According to the findings, there is a decrease in the amount of NOX emissions up to 11.72 g/kWh and 9.49 g/kWh produced by the cooled EGR engine.

Evaluation of laser cladding of Ti6Al4V-ZrO2-CeO2 composite coating on Ti6Al4V alloy substrate

A titanium metal matrix composite (Ti6Al4V-ZrO2-CeO2) cladding is performed on Ti6Al4V alloy by irradiating a pulsed wave fibre laser source. A varying weight percentage of ceria (CeO2) is added to the composite to study its effect on cladding microstructure, hardness, and wear properties. A detailed microstructure and phase identification study is made using FESEM, XRD, XPS, and EBSD. The presence of CeO2 in the composite refines the microstructure of the clad. It promotes the in-situ formation of ceramic compounds such as Ce1-xO2Zrx, Al2O3, Ti6O, and ZrO2 and restricts acicular α‑titanium growth by favouring equiaxed CeO2 growth. Due to grain refinement and the presence of hard ceramic compounds, the microhardness, COF, fracture toughness, and wear resistance is significantly affected with the variation of CeO2 in the cladding. The lowest coefficient of friction (COF) and highest hardness value of 0.21 and 700HV300 were obtained with samples containing 5 wt% of CeO2. Also, the indicative parameters of wear resistance, such as H/E and H3/E2 computed from the nano-indentation test, are highest in the samples containing 5 wt% of CeO2. The novelty lies in graded grain size and in-situ formed hard and rugged cladding without vertical cracks.