Effects Of Different Sintering Temperatures Research Articles

Effect of sintering temperatures on structural and optical properties of ZnO-Zn2SiO4 composite prepared by using amorphous SiO2 nanoparticles

The effect of different sintering temperatures on structural and optical properties of ZnO-Zn2SiO4 composite was investigated. In this study, a ZnO-Zn2SiO4 composite was prepared by encapsulated zinc nitrate hexahydrate with amorphous silica nanoparticles in deionized water. The amorphous silica nanoparticles were prepared by reacting sodium silicate with ethanol. Zinc nitrate was mixed with the obtained amorphous silica nanoparticles with the ratio of 2:1 and 1.25:1 for Zn:Si and subjected to the different sintering temperatures from 600 to 1000 °C. Field emission scanning electron microscope (FESEM) microstructure showed that samples exhibit spherical morphology up to 700 °C and dumbbell morphology above 800 °C sintering temperature. The formation of Zn2SiO4 crystal phase appears from 700 °C and onwards together with ZnO crystal phase. The gaining of sintering temperature has also raised the amount of Zn2SiO4 phase and band gap values of the ZnO-Zn2SiO4 composite.

Structural Characterization and Magnetic Properties of SrCo2Fe16O27 Hexaferrite Synthesized by Citric Acid Sol-Gel Method

The W -type SrCo2Fe16O27 (SCFO) hexagonal ferrite samples were prepared by the sol-gel method using metal nitrate as raw material, citric acid as complexing agent, and water as solvent. The effects of different sintering temperatures and holding times on the phase composition and morphology properties were explored in detail by using the X-ray diffractometer and field emission scanning electron microscope. The X-ray diffraction, microstructure, and magnetic performance of most optimum sintering temperature and holding time of preparing single-phase SCFO hexagonal ferrite were investigated. The experimental results indicate that the best optimum sintering temperature and holding time of SCFO hexagonal ferrite are 1280 °C and 4 h, respectively. Field emission scanning electron microscopy results indicate that the size of the particles is about 5–10 μ m. The result of magnetic measurement shows that SCFO hexagonal ferrite exhibits the soft magnetic property and the Curie temperature (TC) is ∼ 850 K. Furthermore, by analyzing the Arrott plot, the phase transition near the TC is a secondary phase transition.

Synthesis and Photocatalytic Activity of Ag Doped TiO<sub>2</sub> Nanofibers

Ag/TiO2nanofibers were obtained by sol-gel method combined with uniaxial electrospinning. The effects of different sintering temperatures (400°C, 500°C, 600°C) and different concentrations of silver (0 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%) on photocatalytic activity of TiO2were investigated. The morphology and interface interaction of the Ag/TiO2composites were investigated by SEM, TEM, XRD and UV-visible spectrophotometer. The experimental results showed that the diameter of the fiber sintered at 400°C is about 120 nm and the fiber is composed of 10-20 nm small particles. The degradation rate of methylene blue was 71% for the Ag/TiO2composites fiber with 1.0wt% silver and sintered at 400°C.

Effect of different sintering process on flexural strength of translucency monolithic zirconia.

BackgroundSintering process is responsible for the strength of zirconia restoration. This study evaluated the effect of different sintering temperatures and sintered-holding times on flexural strength of translucency monolithic zirconia.Material and MethodsOne hundred and thirty five zirconia bar specimens (width-length-thickness = 10×20×1.5 mm) were prepared from yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic and randomly divided into nine groups to be sintered at different temperatures [decreasing- (SD, 1350°C), regular- (SR, 1450°C), and increasing- (SI, 1550°C) sintering temperature] and different sintered-holding times [shortening- (HS, 60 min), regular- (HR, 120 min), and prolonged- (HP, 180 min) sintered-holding time]. Flexural strength was determined using three-point bending test in a universal testing machine at 1 mm/min crosshead speed. An analysis of variance (ANOVA) and Tukey’s multiple comparisons were used to determine for statistically significant difference of flexural strength (α=0.05). Weibull analysis was applied for survival probability, Weibull modulus (m), and characteristics strength (σo) of the flexural strength. The crystal sizes were microscopically examined using scanning electron microscope (SEM). The phase composition of zirconia was determined using X-ray diffraction (XRD).ResultsThe mean±sd (MPa), m, and σo of flexural strength were 1080.25±217.19, 5.54, and 1167.53 for SDHS, 1243.41±233.17, 5.19, and 1352.30 for SDHR, 1298.92±235.68, 6.24, and 1394.79 for SDHP, 1303.34±171.87, 8.40, and 1377.90 for SRHS, 1331.73±278.84, 5.31, and 1444.50 for SRHR, 1348.13±283.35, 5.32, and 1460.68 for SRHP, 1458.45±289.19, 4.51, and 1604.41 for SIHS 1581.34±190.56, 8.20, and 1675.21 for SIHR and, 1604.10±139.52, 12.57, and 1667.90 for SIHP. The flexural strength was significantly affected by altering sintering temperatures and holding times (p<0.05). Enlarging grain size and increasing t→m phase shifting related with raising temperatures and times.ConclusionsIncreasing sintering temperature and prolonged sintered-holding time lead to enhancing flexural strength of translucency monolithic zirconia, and are suggested for sintering process to achieve durable restoration. Key words:Flexural strength, monolithic zirconia, sintering temperature, sintered-holding time.

Effect of sintering process on color parameters of nano-sized yttria partially stabilized tetragonal monolithic zirconia.

BackgroundSintering process is responsible for aesthetic of zirconia restoration. This study evaluated the effect of different sintering temperatures and sintered-holding times on color parameters of monolithic zirconia.Material and MethodsOne hundred and thirty five zirconia bar specimens (width-length-thickness = 10×20×1.5 mm) were prepared from yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic and randomly divided into nine groups to be sintered at different temperatures [decreasing- (SD, 1350°C), regular- (SR, 1450°C), and increasing- (SI, 1550°C) sintering temperature] and different sintered-holding times [shortening- (HS, 60 min), regular- (HR, 120 min), and prolonged- (HP, 180 min) sintered-holding time]. Color appearance (ΔE), translucency parameter (TP), contrast ratio (CR), and opalescence parameter (OP) were determined with spectrophotometer. An analysis of variance (ANOVA) and Tukey’s multiple comparisons were used to determine for statistically significant difference of color parameters (α=0.05). Crystal sizes were microscopically examined using scanning electron microscope (SEM), and phase composition of zirconia was determined using X-ray diffraction (XRD).ResultsThe mean±sd for ΔE, TP, CR, OP were 82.28±1.27, 1.4±0.13, 0.982±0.004, 1.25±0.15 for SDHS, 78.38±0.74, 2.16±0.10, 0.967±0.005, 1.90±0.11 for SDHR, 74.43±0.91, 2.24±0.10, 0.964±0.004, 1.94±0.09 for SDHP, 76.31±1.22, 3.03±0.10, 0.945±0.003, 2,50±0.09 for SRHS, 74.51±1.27, 3.19±0.17, 0.942±0.003, 2.65±0.16 for SRHR, 73.94±0.49, 3.42±0.10, 0.937±0.003, 2,83±0.09 for SRHP, 76.30±0.43, 3.16±0.09, 0.937±0.002, 2.48±0.09 for SIHS 76.73±1.15, 3.05±0.20, 0.939±0.005, 2.38±0.17 for SIHR, and 75.32±1.37, 2.95±0.18, 0.942±0.006, 2.33±0.15 for SIHP. The ΔE, TP, CR, and OP were significantly affected by altering sintering temperatures and holding times (p<0.05). Increasing sintering temperature and extending sintering time significantly improved color appearance, translucency, contrast, and opalescence of Y-TZP (p<0.05) as evidenced by enlarging grain size and increasing t→m phase shift.ConclusionsRaising sintering temperature and prolonging sintering time lead to better color appearance, translucency, contrast and opalescence of nano-sized monolithic Y-TZP, and are suggested for sintering process. Key words:Color appearance, contrast, monolithic zirconia, opalescence, sintering process, translucency.

Synthesis and study of lithium silicate glass-ceramic

The lithium silicate glass-ceramic was synthesized by conventional solid-state methods at low sintering temperatures. The effects of different sintering temperature on the crystal composition, microstructure, flexural strength, bulk density, thermal expansion coefficient (TEC) and microwave dielectric properties of lithium silicate glass ceramic have been investigated in detail. The research shows that the lithium silicate ceramic was synthesized successfully at a lower temperature (1010 °C). Excellent properties obtained at 1010 °C for 30 min: the flexural strength σ = 189.782 Mpa, the coefficient of thermal conductivity λ= 7.807 w/(m k), er = 6.11, Q × f = 3686 GHz, the bulk density was 2.429 g/cm3 and α = 10.6992 × 10− 6/°C, indicating its potential value for LTCC application.

Microstructural stability of spark-plasma-sintered Wf/W composite with zirconia interface coating under high-heat-flux hydrogen beam irradiation

Tungsten is considered as the most suitable material for the plasma-facing armour of future fusion reactors. However, in spite of many advantageous properties, pure tungsten has a major drawback, namely, brittleness at lower temperatures and embrittlement by neutron irradiation. Tungsten fibre-reinforced tungsten (Wf/W) composites are thought to be a promising candidate material for armour owing to the pseudo-toughness effect which is based on controlled cracking of coated interfaces. In this material concept, the reliability of the material during service relies on the fabrication quality as well as the stability of microstructure, particularly, of the interfacial coating under high-heat-flux loads.In this paper, the durability and chemical stability of Wf/W composite specimens under cyclic heat-flux loads up to 20 MW/m² (surface temperature: 1260 °C) was investigated using hydrogen neutral beam. The bulk material was fabricated by means of spark-plasma-sintering (SPS) method using fine tungsten powder and a stack of tungsten wire meshes as reinforcement where the surface of the wire was coated with zirconia thin film to produce an engineered interface. The impact of plasma beam irradiation on microstructure was examined for two kinds of specimens produced at different sintering temperatures, 1400 °C and 1700 °C. Results of microscopic (SEM) and chemical (EDX) analysis are presented comparing the microstructure and element distribution maps obtained before and after heat flux loading. Effects of different sintering temperatures on damage behaviour are discussed. The present composite materials are shown to be applicable as plasma-facing material for high-heat-flux components.

Investigation on the effect of sintering temperature on kaolin hollow fibre membrane for dye filtration.

Despite its extraordinary price, ceramic membrane can still be able to surpass polymeric membrane in the applications that require high temperature and pressure conditions, as well as harsh chemical environment. In order to alleviate the high cost of ceramic material that still becomes one of the major factors that contributes to the high production cost of ceramic membrane, various attempts have been made to use low cost ceramic materials as alternatives to well-known expensive ceramic materials such as alumina, silica, and zirconia in the fabrication of ceramic membrane. Thus, local Malaysian kaolin has been chosen as the ceramic material in this study for the preparation of kaolin hollow fibre membrane since it is inexpensive and naturally abundant in Malaysia. Due to the fact that the sintering process plays a prominent role in obtaining the desired morphology, properties, and performances of prepared ceramic membrane, the aim of this work was to study the effect of different sintering temperatures applied (ranging from 1200 to 1500°C) in the preparation of kaolin hollow fibre membrane via dry/wet phase inversion-based spinning technique and sintering process. The morphology and properties of membrane were then characterised by SEM, AFM, FTIR, XRD, and three-point bending test, while the performances of membrane were investigated by conducting water permeation and Reactive Black 5 (RB5) dye rejection tests. From the experimental results obtained, the sintering temperature of 1400°C could be selected as the optimum sintering temperature in preparing the kaolin hollow fibre membrane with the dense sponge-like structure of separation layer that resulted in the good mechanical strength of 70MPa with the appreciable water permeation of 75L/hm2bar and RB5 rejection of 68%.

Effect of sintering temperature on thermal stability of Zn0.2Fe1.05NiMn0.75O4 ceramic materials by homogeneous co-precipitation method

The Zn0.2Fe1.05NiMn0.75O4 ceramic materials with different sintering temperatures are synthesized by homogeneous co-precipitation method. The effects of different sintering temperatures on the structure, electrical properties and stability of the ceramic materials are characterized by X-ray diffraction, scanning electron microscope, electrical measurement and impedance analysis. The results show the ceramic powders calcined at 800 °C can form a single cubic spinel structure NiFe2O4 phase, which exhibits great stability at sintering temperature from 1150 to 1300 °C. The values of B25/50 constant, ρ25 and Ea of Zn0.2Fe1.05NiMn0.75O4 ceramic samples at different sintering temperatures are in the range of 3786–3881 K, 84–134 KΩ cm and 0.327–0.335 eV, respectively. The values of relative resistance drift (ΔR/R0) are in the range of 0.58–0.78 % and have a minimum at 1300 °C after aging test at 125 °C for 600 h. The Zn0.2Fe1.05NiMn0.75O4 ceramic materials are desirable for high stability thermistor applications.

Electrochemical investigation of Pr2CuO4-based composite cathode for intermediate-temperature solid oxide fuel cells

Pr2CuO4-xCe0.9Gd0.1O1.95 (PCO-xCGO, x = 0, 10, 20, 30, 40, 50 wt%) composite cathodes were investigated for potential application in intermediate-temperature solid oxide fuel cells (IT-SOFCs). The effect of different sintering temperature on the microstructure and electrochemical performance of the composite cathode was observed. The oxygen reduction reaction (ORR) mechanism was analyzed by the electrochemical impedance spectroscopy. It was found that the addition of CGO in PCO cathode significantly reduced the polarization resistance (Rp). The lowest Rp of 0.12 Ω cm2 for PCO-40CGO composite cathode at 700 °C in air. Oxygen partial pressure dependence study indicates that the charge transfer process is rate-limiting step for ORR on the electrode. The maximum exchange current density i0 of the PCO-40CGO composite cathode was 15.10 mA cm2 at 700 °C. All above properties indicate that the PCO-40CGO composite is a promising cathode material for IT-SOFCs.

The effects of sintering temperature and duration on the flexural strength and grain size of zirconia

Objective: This study investigated the effect of different sintering temperatures and times on the flexural strength and grain size of zirconia.Material and methods: Zirconia specimens (In-Coris ZI, In-Coris TZI, 120 samples) were prepared in a partially sintered state. Subsequently, the specimens were randomly divided into three groups and sintered at different final sintering temperatures and for various durations: 1510 °C for 120 min, 1540 °C for 25 min and 1580 °C for 10 min. Three-point flexural strength (for 120 samples, 20 samples per group) was measured according to the ISO 6872: 2008 standards. The grain sizes were imaged by scanning electron microscopy (SEM) and the phase transitions were determined by X-ray diffraction (XRD). The data were analyzed using one-way ANOVA and Duncan tests (p < 0.05).Results: The highest flexural strength was observed in ZI and TZI samples sintered at 1580 °C for 10 min. The differences between the ZI samples sintered at 1510 °C for 120 min and those sintered at 1540 °C for 25 min were statistically insignificant. Also, TZI samples sintered at 1510 °C for 120 min and those sintered at 1540 °C for 25 min also did not show any statistically significant differences. There were no visible differences in the grain sizes between the ZI and TZI specimens. The XRD patterns indicated similar crystalline structure for both materials subjected to the three different procedures.Conclusions: The results of this study showed that experimented high sintering temperature and short sintering time combination increases the flexural strength of zirconia.

Effect of sintering temperature on the electromechanical properties of 0.945Bi0.5Na0.5TiO3-0.055BaZrO3 ceramics

In this work, lead-free 0.945B0.5N0.5TiO3-0.055BaZrO3 (BNT-BZ) ceramics were synthesized by using conventional solid-state reaction method and the effect of different sintering temperatures (1145–1200 °C) on its structure and electromechanical properties were investigated. XRD patterns revealed single a phase-perovskite structure for all samples sintered at different temperatures. An optimum sintering temperature enhanced densification, promoted grain growth, and improve the dielectric and piezoelectric properties. However, at low (1145 °C) and high (1200 °C) sintering temperatures, the BNT-BZ ceramics showed inferior electromechanical properties. BNT-BZ ceramics sintered at an optimum temperature (1175 °C) showed an enhanced strain (0.39%) response at an applied electric field of 7 kV/mm with a high dynamic piezoelectric coefficient (d 33* = 557 pm/V). These results can be attributed to the high density of the BNT-BZ ceramics sintered at 1175 °C.

Effects of Different Sintering Temperature on the Microstructure and Piezoelectric Properties of Pb(Nb&lt;sub&gt;2/3&lt;/sub&gt;Zn&lt;sub&gt;1/3&lt;/sub&gt;)&lt;sub&gt;x&lt;/sub&gt;(Zr&lt;sub&gt;52&lt;/sub&gt;Ti&lt;sub&gt;48&lt;/sub&gt;)&lt;sub&gt;1-X&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Ceramics

In this paper, the effects of different sintering temperature on the microstructure and piezoelectric properties of Pb(Nb2/3Zn1/3)0.03(Zr52Ti48)0.97O3(PNZZT) ceramic samples were investigated. The Pb(Nb2/3Zn1/3)0.03(Zr52Ti48)0.97O3 ceramics materials was prepared by a conventional mixed oxide method. In the period of the experiment, the relationship between crystallographic phase and microstructure were analyzed by X-ray diffraction(XRD) and scanning electron microscopy(SEM) respectively. The XRD patterns shows that all of the ceramic samples are with a tetragonal perovskite structure. Along with sintering temperature increased and the x is 0.03, the grain size gradually become big. Through this experiment, it has been found that when the x is 0.03 and sintered at 1130°C for 2 h, the grains grow well, the grain-boundary intersection of the sample combined well and the porosity of the ceramics decreased, an excellent comprehensive electrical properties of the Pb(Nb2/3Zn1/3)0.03(Zr52Ti48)0.97O3 samples can be obtained. Its best electrical properties are as follows: dielectric constant (ε) is 1105, dielectric loss(tg) is 0.017, electromechanical coupling coefficient (Kp) is 0.287, piezoelectric constant(d33) is 150PC/N

Processing and properties of ferroelectric Bi0.5(Na0.65K0.35)0.5TiO3 ceramics under the effect of different sintering temperature

Lead-free ferroelectric Bi0.5(Na0.65K0.35)0.5TiO3 ceramic was synthesized after optimizing the sintering temperature in the range 1070–1110 °C. The best dielectric, ferroelectric and piezoelectric values were obtained in the highly dense sample sintered at 1090 °C. A high dielectric constant (780 at 10 kHz at room temperature), high phase transition maxima (Tm = 330 °C) and conductivity mechanisms were reported. Good ferroelectric values in the P–E loop (Pr = 27.2 μC cm−2, Ec = 25 kV cm−1) with high piezoelectric coefficient (d33 = 132 pC N−1) and fatigue-free behavior were obtained.

Effect of Heat Treatment on Structural, Magnetic and Electric Properties of Z-Type Barium Cobalt Hexaferrite Powder

Z-type hexaferrite with composition Ba3Co2Fe24O41has been synthesized using a sol-gel auto combustion technique. The obtain combusted powder was sintered at 500 OC and followed by 950 OC for 4 hrs in a muffle furnace. The effect of different sintering temperature on crystal structure, crystallite size, microstructure and dielectric properties were systematically investigated. The prepared barium cobalt hexaferrite powder samples were characterized using different experimental techniques like FTIR, XRD, AC conductivity and specific magnetization measurements. It was observed from XRD results that heat treatment conditions play significant role in the formation of hexaferrite phase. AC conductivity measurements were carried out at room temperature in frequency range of 20Hz to 2MHz. All the samples show the frequency dependent phenomena, i.e. the AC conductivity increases with increasing frequency.

Preparation of glass–ceramic foams from the municipal solid waste slag produced by plasma gasification process

The glass–ceramic foams were prepared using high content of municipal solid waste (MSW) slag (50–70%) generated by plasma gasification process. Calcium carbonate and sodium borate were used as foaming agent and flux agent, respectively. The effects of different sintering temperature on the density, mechanical strength and crystalline phases were discussed. The results showed that the glass–ceramic foams with 70wt% MSW slag sintered at 920°C exhibited an excellent strength-to-density ratio (crushing strength exceeding 2.5MPa, with a density below 0.3g/cm3), due to the precipitation of micro-crystals. The preparation of foams utilizing high content of MSW slag eliminates the problem of its disposal and displays huge commercial interests.

The Influence of Sintering Temperature on the Microstructure and Electrical Properties of BiFeO&lt;sub&gt;3&lt;/sub&gt; Ceramics

This study reports the synthesis of bismuth ferrite ceramics (BiFeO3, BFO) by the sol-gel method and the effect of different sintering temperatures (800 °C, 820 °C, 850 °C, 880 °C, 900 °C) on the crystal structure, morphology, dielectric properties and ferroelectric properties of the bismuth ferrite ceramics. It is observed that the bismuth ferrite phase are formed when the molar ratio of bismuth and ferric is 1.025 : 1, and the bismuth ferrite ceramics have less impurity phase at all the five sintering temperature. The morphology studies revealed that the grain of bismuth ferrite ceramics is spherical and the grain size increases with the increasing of the sintering temperature. When the bismuth ferrite ceramics with excessive bismuth sintered at 820 °C, it exhibits the higher dielectric constant and the lower dielectric loss, the remnant polarization and the coercive field are 0.35 μC/cm2 and 4.03kV/cm, respectively. The observed ferroelectricity in bismuth ferrite ceramics owes to the point defects associated with oxygen vacancy defects as well as the smaller size effect.

Effect of Different Sintering Temperature on the Performance of Mullite-Corundum Refractory Materials

Al (OH)3, Suzhou kaolin, AlF3 and V2O5 were premixed and pelleted to form the precursor for fabricating the mullite whisker, and then the precursor was added into the calcined bauxite and Suzhou kaolin mixture according to a certain mass percent. The mullite-corundum refractory materials with well-dispersed needle-like mullite formed in-situ were prepared. Through studying the effect of different sintering temperatures on the performances of the as-fabricated mullite-corundum refractory materials, it was concluded that the appropriate sintering temperature was 1450 °C. X-ray diffraction (XRD), scanning electron microscopy (SEM), water absorption, bending strength, coefficient of thermal expansion and the first thermal stress fracture factor were used to characterize and evaluate the materials. The results show that the sintering character and thermal expansion coefficient of the refractory materials increase with the rising sintering temperature. The bending strength of the refractory materials sintered at 1500 °C presented the maximum value and the first thermal stress fracture factor appeared the highest value at 1450 °C.

Preparation and properties of low temperature sintered CaO-B2O3-SiO2 microwave dielectric ceramics using the solid-state reaction

The LTCC CaO-B2O3-SiO2 (CBS) ceramics were synthesized via solid-state reaction process without any sintering aid. The effects of different sintering temperatures and B2O3 content on the microwave and mechanical properties were investigated. The results show that the best sintering temperature is around 950 °C and increasing amount of B2O3 promotes the crystallization of CaB2O4 enhancing the flexure strength of the CBS ceramics. However, the dielectric and mechanical properties deteriorated rapidly while the amount of B2O3 exceeded 25 wt.%. The sample with 20.5 wt.% B2O3 sintered at 950 °C had the best properties with ɛ r = 6.06; tanδ = 0.0015 (1 MHz) and a high flexure strength σ f > 180 MPa.

Effects of sintering temperature and graphite addition on the mechanical properties of aluminum

The effects of different sintering temperatures, namely 400, 500 and 600°C, on the mechanical properties of four aluminum–graphite alloys were reported. Different percentages of exfoliated graphite nanoplatelets particles (xGnP) were added to pure aluminum by using the powder metallurgy technique to produce Al-0wt.%xGnP, Al-1wt.%xGnP, Al-3wt.%xGnP, and Al-5wt.%xGnP. The density, fracture surface, compression, and hardness measurements were carried out to report the mechanical properties of the different aluminum–xGnP alloys. Combined data indicated that the Vickers hardness and compressive strength increase, on the other hand, the density decreases with increasing the graphite content in the Al alloys.