Sintering Procedure Research Articles

Charge compensation and solid-state lighting application for dysprosium-activated Ba2TeP2O9 phosphor

In this study, trivalent dysprosium (Dy 3+ ) activators were doped into barium tellurooxyphosphate Ba 2 TeP 2 O 9 (BTP) by a solid-state sintering procedure, where alkali metal (A = Li, Na, and K) ions co-doped as charge compensator were aimed at improving the luminescent performance. To investigate optical absorption behavior, the electronic structure of the BTP host was realized via the density functional theory (DFT) method. The BTP:Dy 3+ phosphor excited by 349 nm shows bright yellow emission. When the concentration of the Dy 3+ activator is greater than 0.03 mol, concentration quenching occurs owing to dipole–dipole interaction. After doping 0.03 mol A + ions into the BTP:0.03Dy 3+ phosphor, the emission intensity of BTP:0.03Dy 3+ enhances by 1.18 (Li + ), 1.43 (Na + ), and 2.32 times (K + ). Additionally, the BTP:0.03Dy 3+ ,0.03 K + phosphor exhibits satisfactory thermal stability. A white light-emitting diode (w-LED) was successfully fabricated from the BTP:0.03Dy 3+ ,0.03 K + and commercial blue phosphors with a 365 nm LED chip. The study reveals that the BTP:0.03Dy 3+ ,0.03 K + phosphor is a prospective yellow-emitting candidate for w-LED. • Due to the asymmetric coordination of Dy 3+ , the yellow-emitting of BTP:Dy 3+ is stronger than its blue-emitting. • Co-doping K + into the host can both produce minimal lattice distortion and reduce the structural vacancy. • The thermostability of BTP:0.03Dy 3+ ,0.03 K + is competitive with that of the commercial yellow phosphor. • The concentration quenching mechanism is the dipole–dipole interaction.

Microstructures and mechanical properties of biphasic calcium phosphate bioceramics fabricated by SLA 3D printing

Porous biphasic calcium phosphate (BCP) bioceramics are considered to be the most promising bone repair materials in clinical medicine. Stereolithography (SLA) 3D printing can precisely fabricate bioceramic scaffolds with complex porous structure. During this process, how to obtain a suitable sintering procedure for BCP bioceramics by SLA 3D printing is the key to determine the microstructures and mechanical properties, but this is absent. In this present study, we prepared BCP bioceramics with superior densification and mechanical properties by SLA 3D printing, and mainly investigated the effects of sintering temperature and condition on the microstructures and mechanical properties of SLA 3D printed BCP bioceramics for the first time. At the optimized procedure of sintering temperature 1250 °C for 2 h, the 3D printed BCP bioceramics showed uniform shrinkage in all directions, and especially the mechanical properties were close to that of human cortical bone. Furthermore, complex porous BCP scaffolds with high porosity (51.49 %) and compressive strength (8.14 MPa) were successfully obtained. BCP bioceramics greatly promoted the proliferation of MC3T3-E1 cells by the release of Ca and P ion and presented excellent bioactivity. This work proves that SLA 3D printing technology can prepare BCP bioceramics with high mechanical and functional properties, and provides a new route for manufacturing high performance BCP bioceramic scaffolds with complex structure by SLA 3D printing for repairing bone defect in clinical.

PREPARATION OF YB-DOPED SRCEO3 SPUTTER TARGETS FOR PROTONIC SOLID OXIDE FUEL CELLS

A comprehensive study was carried out starting from powder synthesis to sintering procedure in order to produce a phase-pure SrCe0.95Yb0.05O3-δ sputter target. In the powder synthesis, the effect of chelating and polymerization agents on the formation of single-phase SrCe0.95Yb0.05O3-δ was investigated in detail. In this regard, citric acid, EDTA, and their combinations in different ratios were evaluated as chelating agents. The calcination temperature, ranging from 1000 °C to 1300 °C, was also investigated to reveal its effect on the formation of possible secondary phases. Following the powder synthesis, SrCe0.95Yb0.05O3-δ sputter target with dimensions of ~50 mm diameter and ~3 mm thickness was produced by powder pressing with deformable compaction die and the subsequent sintering at 1300 °C for 10 hours. A relative density of 0.95 was achieved in SrCe0.95Yb0.05O3-δ targets as a result of the procedure in question without the use of a sintering aid.

The influence of particle size distribution on rheological properties of fused silica pastes for direct ink writing

Additive manufacturing of ceramics through the direct ink writing method becomes possible when the effective parameters on rheology are optimized accurately. Successful manufacturing first requires the easy flowing of the ink through the nozzle and then a suitable viscoelastic response for the shape retention of the 3D printed structure. In the present study, fused silica pastes with different particle size distributions varying from D90 of 5–50 µm were prepared for direct ink writing of porous structures. The rheological properties of the pastes, including flow behavior and the viscoelastic moduli variations, were investigated to study the influence of particle size and its distribution on fabricating complex structures. Through investigations, it was found that the narrower size distributions were more appropriate for direct ink writing of fused silica pastes. As the distribution became narrow, the shear thinning behavior was intensified, and the pastes showed high elasticity. The sintering procedure was performed using microwave radiation to suggest a fast process for manufacturing fused silica complex parts containing partially crystallized cristobalite phase and providing porosity of about 10% and a relative density of 90%.

Study of reaction-bonded silicon carbide samples using visual-optical and radiographic methods of nondestructive control

Products based on silicon carbide are widely used in different industrial applications due to a high level of their mechanical, thermal, and operational properties. When the reaction sintering procedure is used to obtain silicon carbide materials, the preformed porous samples consisting of silicon carbide powders, carbon filler, and coke binder are subjected to liquid-phase silicizing (silicon melt infiltration (MI) in a vacuum furnace. We present the results of studying samples of reaction-bonded silicon carbide (RBSC) using visual-optical and radiographic methods of non-destructive control. Silicizing of carbon-silicon carbide materials can result in formation of defects on their surface and in the bulk of the material. The visual-optical method is shown to be rather simple and extremely informative procedure which ensures the detection of surface defects in the form of pores, cracks, chips, shells, and can also provide indirect indications of possible presence of internal defects in the form of underimpregnated areas. The samples silicized with a larger number of silicon drops on their surface exhibit a higher density and a smaller number of underimpregnated areas which can be detected using radiographic control. X-ray control carried out for several exposures differing in the angle of sample rotation by 90° provided 95%-probability of detecting internal volumetric and planar defects. The results obtained can be used in the manufacture of RBSC-based parts of tribotechnical duty, shut-off valves and other wear-resistant products.

Ppb-level H2S gas sensor based on CuNi-MOFs derivatives for meat freshness detection at low temperature environment

H2S is usually used as one of the landmark gases for meat freshness detection under low temperature storage conditions. In this paper, the NiO-doped CuO composite derived from MOFs was synthesized by a low temperature (−25 ℃) precursor hydrothermal and sintering procedure for H2S detection. The influence of precursor solution temperature and sintering temperature on the structure of MOFs derivatives were discussed by SEM, TEM, and XRD characterization. The hydrothermal method of low-temperature precursor has guiding significance in improving the gas response performance of MOFs/MOFs derivatives. The sensor based on NiO-doped CuO composites derived from MOFs exhibited a ppb-level response to H2S gas. The sensor response is 106 % to 50 ppb H2S. Meanwhile, the sensor has good selectivity, and the response and recovery time are 115 s and 251 s, respectively. The low temperature precursor hydrothermal method directly affected the morphology and structure of MOFs derivatives by regulating the kinetics for MOFs nucleation and crystal growth, obtains more active adsorption sites. In addition, the composite has good sensing performance for H2S at the ambient temperature of 4 ℃ and −18 ℃, which verified the effectiveness for the detection of meat spoilage under a low temperature storage. Furthermore, the sensor based on NiO-doped CuO composites is a good candidate for H2S gas detection in meat freshness evaluation. Finally, an integrated circuit detection system was designed to detect H2S gas at different ambient temperatures. This work provides a new idea for meat freshness detection in a cold storage environment.

Effects of intermetallic phases on electrochemical properties of powder metallurgy Mg-6%Al-5%Pb anode alloy used for seawater activated battery

The changes in intermetallic phases of Mg-6%Al-5%Pb (Mg-Al-Pb) alloy prepared by powder metallurgy and their effects on electrochemical properties were studied. Experimental results showed that coarse Mg17Al12 phases (with size ranges from 20 μm to 70 μm) and fine Mg2Pb phases (with the size of 100 nm scale) formed in the mixed Al, Pb and Mg powder during the hot press sintering procedure. Fine Mg2Pb phases exhibit strong diffusional ability to diffuse into Mg17Al12 phases. Extruding further promotes the diffusion of Mg2Pb phases into Mg17Al12 phases. Solution treatment produced a mixed microstructure which is Mg17Al12 phase containing Mg2Pb phases inside and made other Mg2Pb phases homogeneously distributed in Mg matrix. Mg17Al12 phases and the gathered Mg2Pb phases will accumulate the Mg(OH)2 corrosion products, which impedes the subsequent discharge behavior. Homogeneously distributed Mg2Pb phases will fall off during discharge, which makes the discharge curve more stable. The mixed microstructure has positive effect on corrosion resistance and discharge potential. Therefore, solution-treated alloy shows the highest negative potential and the smoothest curve during the galvanostatic discharge test. Compared with the commercial AZ61 sheet, solution-treated alloy exhibit much higher anode properties in Mg/PbCl2 battery test. Thus, the solution-treated alloy could serve as an excellent anode in seawater-activated batteries.

A Novel Nanostructured Mullite Feedstock for Environmental Barrier Coatings via Atmosphere Plasma Spraying

A novel strategy is proposed to design an exclusive nanostructured mullite spherical feedstock for environmental barrier coatings (EBCs) via atmosphere plasma spraying (APS). The nanostructured mullite spherical feedstocks are successfully obtained by the procedure of spray drying, solid-phase sintering and flame spheroidization. The crystal grain size of nano-mullite increases with annealing temperature. When the temperature is as high as 1500 °C, the reaction of Al2O3 and SiO2 can be fully completed. The average size is 52 nm for the grain of mullite in feedstocks sintered at 1500 °C, which can be reduced from 52 nm to 48 nm by flame spheroidization treatment as well. Meanwhile, the nanostructured spherical feedstocks show high density and good flowability, which is suitable for APS. The mullite coatings is successfully prepared on a SiC substrate by APS, in which both the nanoscale crystals and nanostructures are perfectly kept as designed. Furthermore, there is no crack appeared in the nanostructured mullite coatings. Thus, the nanostructured mullite feedstock is one of promising candidates for the high performance EBCs.

Insights into the Relationship between Crystallite Size, Sintering Pressure, Temperature Sensitivity, and Persistent Luminescence Color of Gd2.97Pr0.03Ga3Al2O12 Powders and Ceramics

In order to obtain Gd2.97Pr0.03Ga3Al2O12 powders with different crystallite sizes, a modified Pechini (sol–gel) method was used. Powders were then used for the preparation of ceramics by a high-pressure low-temperature sintering method. The impact of crystallite size and pressure applied during the sintering procedure on conventional and persistent luminescence was investigated and analyzed. It was found that the emission color is strictly dependent on the crystallite size, as such phenomenon may be used in the field of advanced anti-counterfeiting. The spectroscopic properties of Gd2.97Pr0.03Ga3Al2O12 were characterized by means of photoluminescence measurements. The kinetics of luminescence were measured in order to analyze the energy transfer between 3P0 and 1D2 excited states that also take an active role in the persistent luminescence process. It was found that an increase in the crystallite size led to a higher energy transfer from the 3P0 to 1D2 level and a change in the emission color. As such, it was studied for potential application in ratiometric optical thermometry. The effect was also investigated in terms of persistent luminescence. It was also found that the sintering pressure causes changes in the crystallographic parameters of the powders and, in consequence, has a great impact on the optical properties of ceramics. The conducted research gives insights into the mechanism of persistent luminescence and expands the application field of optical storage materials.

Sensitive non-invasive electrochemical sensing of glucose in saliva using amorphous SnOx decorated one-dimensional CuO nanorods rich in oxygen vacancy defects

The non-enzymatic glucose sensor with high sensitivity is significant for non-invasive glucose continuous monitoring in saliva. Herein, the composite with amorphous SnOx decorated one-dimensional CuO nanorods were prepared via the hydrothermal and sintering procedure. The sensitivity of sensor is 2303 μA mM−1 cm−2, and the detection range of sensor is 1 μM to 6000 μM. For interferences such as dopamine, lactic acid, ascorbic acid, and sodium chloride, the sensor has good selectivity. TPD confirmed that this composite with amorphous SnOx decorated CuO nanorods has oxygen vacancy defects. This enhanced performance should be attributed to the addition of amorphous SnOx, which induces more oxygen vacancy defects. This sensor with good electrochemical performance may be used for continuous detection of saliva with low glucose content. The sensor constructed by CuO-SnOx composite could detect the changes of glucose content in saliva before and after meals. Measuring glucose in saliva samples at different time intervals confirmed that it was closely related to the blood glucose level measured with a commercially available blood glucose meter. Oxygen-enriched vacancy defects induced by structure can improve the performance of sensors, which may provide some new ideas for the synthesis of high-performance sensor composite.

Allochroic effect of praseodymium doped neodymium molybdate pigment synthesized by solid-state reaction

This paper was to synthesize praseodymium-doped neodymium molybdate allochroic pigments with different molar ratios of molybdenum (Mo), neodymium (Nd) and praseodymium (Pr) through solid-state reactions. The pigments synthesized were investigated by X-ray diffraction (XRD), selected area electron diffraction (SAED), thermogravimetry and differential thermal analysis (TG-DSC), diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS) and colorimeter. The results show that a pure neodymium molybdate (i.e., Nd2MoO6) can be formed after sintering at 1000 °C for 3 h, and praseodymium-doped neodymium molybdate can be synthesized after sintering at 1000 °C for 3 h due to praseodymium ions entering in the lattice of Nd2MoO6. The crystal structure in the pigment synthesized can transform from cubic to tetragonal depending on the molar ratio of neodymium/molybdenum and sintering procedure. The color properties of pigments were measured in color space CIEL*a*b* under different standard illuminants (i.e., solar-light (D65), incandescent light (A), cool white fluorescent lamp (F2), and three-band fluorescent lamp (F11)). The results show that the colors of the pigments vary under different illuminants. According to the color difference (ΔE) analysis, neodymium molybdate pigment exhibits a maximum color difference of 10.69, and the maximum color difference of praseodymium-doped neodymium molybdate pigment with doping content of 0.2 increases to 17.63 due to the Pr3+ ions substitution for Nd3+ ions in the lattice. In addition, the color difference of the pigments with allochroic effect was discussed based on the colorimetry. The color difference of the pigments is due to a high reflectance region at 540–550 nm and a low reflectance region at 380–500 nm.

Thermal and Mechanical Behaviour of Heat-resistant Clay-silica Composites

The ceramic composite with different proportions of clay and silica was prepared with a grain size of 70 μm and the weight percentage was selected for four groups (clayx silica100-x) were x q15, 25, 30 and 50. In this manuscript, for each pressured sample, a sintering procedure was carried out for 3 hours under static air and at various sintering temperatures (1000, 1100, 1200, 1400)°C. After sintering, the density, porosity, water absorption, compression strength and thermal conductivity were measured. The best results were obtained using a mixture of 15% clay and 85% silica which were sintering at 1400°C for three hours under air.

Fabrication of fine-grained Li2TiO3 ceramic pebbles with enhanced crush load by rolling method: Optimization of Li/Ti ratio and sintering procedure

Li2TiO3 ceramic pebbles ought to have high crush strength and uniform microstructure for safety operation and efficient tritium release. Fabrication techniques should be optimized to achieve the desired properties. In our previous work, Li-rich Li2TiO3 ceramic pebbles with a satisfied crush load of 41 N were fabricated by a productive rolling method. Based on this work, effects of raw materials selection, Li/Ti ratio, and sintering atmosphere on Li-Ti-O phase formation were investigated. The pebbles with homogeneous microstructure and enhanced crush load of 92 N were obtained by optimizing the Li/Ti ratio and sintering procedure. The optimal Li/Ti ratio is determined to be 2.5, and the pebbles should be first sintered in air to achieve a high crush strength and then annealed in vacuum to remove the carbonate impurities.

Effects of sintering protocol and dipping time on the optical properties of monolithic zirconia

Statement of problemThe use of monolithic zirconia for restorations has become popular. However, the effects of the coloring process and sintering procedure on the optical properties of monolithic zirconia remain unclear. PurposeThe purpose of this in vitro study was to evaluate the effects of the different sintering protocols and dipping times on the CIELab color parameters, color difference (ΔE00), translucency parameter (TP00), opalescence parameter (OP), and contrast ratio (CR) of monolithic zirconia. Material and methodsOne hundred and fifty monolithic zirconia specimens were prepared and divided into 5 groups according to different dipping times in A2 shade coloring liquid: no immersion (D0), 3 minutes (D3), 5 minutes (D5), 7 minutes (D7), and 9 minutes (D9). The specimens were further divided into 3 subgroups according to different sintering protocols (n=10): classic (C); speed (S); and super-speed sintering (SS). The CIE L∗a∗b∗ values, ΔE00, TP00, OP, and CR values were determined with a spectrophotometer. The data were analyzed with 2-way ANOVA and Bonferroni post hoc tests (α=.05). ResultsThe effects of the sintering protocol, dipping time, and interaction of the sintering protocol and dipping time were significant for the L∗, a∗, b∗, ΔE00, TP00, OP, and CR parameters (P<.001). The ΔE00 values of the SS groups were significantly higher than those of the C and S groups for all the dipping times assessed. However, only the CD3 and CD5 groups had ΔE00 values below the acceptability threshold (<1.8). Coloring significantly reduced TP00 values and significantly increased OP and CR values in the colored groups compared with those in the D0 groups. The C and S protocols for different dipping times showed similar optical properties in TP00, OP, CR, and ΔE00 (excluding the D0 and D9 groups) compared with the SS protocol. ConclusionsDifferent sintering protocols combined with various dipping times significantly affected the optical properties of monolithic zirconia. However, C and S sintering with a 3-minute and 5-minute coloring process yielded more favorable optical results than SS sintering and prolonged dipping times.

Oxidation and Cr-evaporation behavior of MnCo based spinel and composite coated AISI 430 steel

This work investigates the importance of the chemical composition and porosity of the coating on reducing the oxidation and Cr-evaporation rate of AISI 430 steel in O2-5%H2O at 800 °C for solid oxide fuel cell (SOFC) interconnect applications. Electrophoretic deposition (EPD) is used to deposit eight different coatings. Mn1.25−0.5xCo1.75−0.5xMxO4 (M = Fe, Cu, and Fe-Cu; and X = 0 and ~0.3) powders are synthesized by the glycine nitrate process (GNP) and applied as spinel (without La2O3) or composite (with La2O3) coatings. The coatings initially show porous structure, and the coating density improvement depends on coating composition. The coating porosity for composite co-doped Fe-Cu MnCo spinel (MCFeCuL) is 28% less than MnCo spinel (MC) after 504 h. All coated samples show lower oxidation and Cr-evaporation rates than uncoated samples. The parabolic oxidation rates are lower for composite coated than the spinel ones, possibly due to the formation of LaCrO3 reducing Cr outward diffusion. Composite MnCo-La2O3 (MCL) shows the lowest oxidation rate. In contrast, coating effectiveness in reducing Cr-evaporation depends on coating density. Cu-doped coatings show less coating porosity with better oxidation and Cr-evaporation behavior than Fe-doped coatings. All coated samples form a densified layer at the thermally grown oxide (TGO) scale/coating interface, playing a crucial role in oxidation resistance and migration of Cr from the TGO scale to the coating. The changes in Cr-evaporation fluxes depending on coating porosity and pore size are calculated and compared with Cr-loss rate measurements. Among the coatings, composite Cu-doped MnCo spinel (MCCuL) and MCFeCuL show better performance than the other ones. This study shows that it is possible to decrease coating porosity and improve the performance of MnCo spinel coatings against corrosion and Cr-evaporation without two-step sintering (at T ≤ 900 °C) procedures.

Microwave assisted processing of X8R nanocrystalline BaTiO3 based ceramic capacitors and multilayer devices

BaTiO3 based multilayer ceramic capacitor (MLCC) is an important component in electronic devices. Achieving high dielectric performance, miniaturisation and cost effectiveness are still challenging. Co-sintering ceramic layers with metal electrodes and use of expensive Pt and high-Pd content compositions as electrodes are other key issues. Thus, the major factors that could lead to cost effectiveness of MLCCs are reduction in sintering temperature and using less expensive metal electrodes without compromising dielectric performance and these traits could auger well for the next generation low-cost high performance electroceramic devices – this is the subject matter of the present study.In this work, initially we have fabricated and analysed the dielectric performance of BaTiO3 (BT) ceramics with different BT particle sizes (50 nm, 100 nm and 200 nm). Based on results, 200 nm BaTiO3 was used for further studies due to its superior dielectric performance. Then, to reduce the sintering temperature and improve the dielectric performance of 200 nm BaTiO3 ceramics, Bi2O3 was used as a dopant which acts both as a sintering aid and helps to improve the dielectric performance. A combination of rare earth dopant system (proprietary from the industrial partner Knowles, UK) with Bi2O3 was also added to tune the defect chemistry of BaTiO3 for enhancement in dielectric performance further. A homogeneously mixed BT-based ceramic slurry system (containing the above dopants) with optimum rheology was developed using a non-aqueous medium, dispersant and a binder system. Addition of glass frits for lowering the sintering temperature and its effect on dielectric performance was also investigated on both discs (made using dry pressing of the powders obtained via drying of the slurry) as well as multilayer ceramic capacitors (MLCCs) fabricated through screen printing. Conventional, microwave and hybrid sintering procedures were employed for the densification of the electroceramic devices and these were characterized for density, microstructure, composition and dielectric performance systematically. Conventional sintering resulted in undesired large micron sized surface features which are detrimental to device durability, whereas formation and growth of these features have been demonstrated to be significantly minimised using the rapid microwave assisted sintering procedures for the first time. Further efficient co-sintering of ceramic layers with less expensive (Ag/Pd) alloy has also been accomplished using the microwave methodology. The resultant BaTiO3 based capacitive devices exhibited high dielectric permittivity, superior X8R performance and low dissipation factor, asserting their massive potential for widespread high temperature applications in automotive, sensing and space sectors.

In-vitro fit of experimental full-arch restorations made from monolithic zirconia.

Fabrication inaccuracies can compromise the fit of large-span monolithic zirconia restorations. Sintering distortion is a particular problem. This study aimed to assess the fit of full-arch restorations made from monolithic zirconia for different abutment configurations. To quantify fit inaccuracies created during the fabrication of experimental large-span restorations, an in-vitro model with eight abutment teeth was equipped with strain gauges. Ten 14-unit restorations were made from monolithic zirconia and seated on the model in turn. For each of the ten restorations, measurements were taken for three different abutment configurations-polygonal, quadrangular, and unilaterally shortened. Strains exerted during seating were recorded in the anterior-posterior and buccal-palatal directions, and the resulting horizontal forces (rhF) were calculated along with the respective abutment deflection (ad). Data were analyzed using Kruskal-Wallis tests at a significance level of 0.05. All restorations could be seated on the multi-abutment model. The restorations exhibited fabrication misfits, tending to be too wide. Mean rhF/ad were largest for the quadrangular configuration (16.8±2.9 N/0.065 mm) and smallest for the polygonal configuration (13.6±4.5 N/0.053 mm). The largest rhF/ad were measured on abutments of the unilaterally shortened configuration, with a maximum deflection of 0.126 mm. For two of three configurations, rhF/ad were significantly larger for the distal abutments than for the other abutments. Even if milling and sintering procedures are optimum, misfit-induced horizontal forces cannot be avoided. Because of the natural tooth mobility, however, the fit of full-arch restorations made from monolithic zirconia might be clinically acceptable.

Physical and mechanical properties of AA2219/BN composites

The main purpose of this paper is to compare the impacts of multiple Boron Nitride particle weight percentages of micro-sized particles and nano-sized particles on the AA2219 hybrid nanocomposite produced via sintering and hot extrusion procedures. The finalized materials are structurally and metallurgically characterized. To conduct a comparative analysis, the weight percentages of Boron Nitride-reinforced particles are varied. When compared to the other samples, the yield strength (270 MPa) and ultimate tensile strength (UTS) of the AA2219 hybrid composite sample-3 (S3) are greatly enhanced.

Comparison of Boron Nitride (BN) reinforced sintered and extruded AA2219 nano-hybrid composite particle size effects on mechanical and metallurgical characteristics

Aluminum metal matrix composites (AMMCs) exhibit extravagant characteristics that have sparked interest in developing new nanocomposite materials among the scientific world. In this paper analysis the effects of BN particle wt% micro and nano sized particles on the properties of the AA2219 hybrid nanocomposite produced via sintering and hot extrusion procedures. In comparison to sintered composite S3, the extruded composite S3 (340 MPa) has 1.234 times the compressive strength.

Effect of Al2O3 nano-particles on Ba(Zr0.95Ti0.05)O3 ceramics prepared by mixed oxide method

In this study, the effect of Al2O3 nano-particles on Ba(Zr0.95Ti0.05)O3 or BZT ceramics prepared by mixed oxide method with various amount of Al2O3 were investigated. The BZT powders were calcined at 1100 °C for 3 h with heating rate of 5 °C/min. The sintering procedure of BZT + x wt.% Al2O3 nano-particles (x = 0.3, 0.7 and 1.0) was carried out at 1300 °C for 2 h with heating rate of 5 °C/min. The results showed that, all XRD patterns of BZT + x wt.% Al2O3 nano-particles ceramics could be matched with a JCPDS data file number 06-0399. The BZT + 0.7 wt.% Al2O3 nano-particles ceramic was showed the highest density about 5.9 g/cm3, Vickers micro-hardness was 8.9 GPa, dielectric constant was 2005 and dielectric loss was 0.01 at 1 kHz frequency.