Effects Of Different Sintering Temperatures Research Articles

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<sub>3</sub> 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.

Investigation of PNN-PZT Thick Films Fabricated by Electrophoretic Deposition

0.2Pb(Ni1/3Nb2/3)O3-(0.8−x)PbTiO3-xPbZrO3 (PNN-PZT) dense piezoelectric thick films with the thickness of about 50 μm were fabricated by electrophoretic deposition(EPD) on Pt wire. Effects of different dispersants to the Zeta potential of the suspension and the microstructures of the PNN-PZT thick films were evaluated. The results shows that suspension with polyethyleneglycol 10000 is more stable than the suspension with polyethyleneglycol 6000, and the thick films deposited from suspension with polyethyleneglycol 10000 is more denser. The effects of different dispersants on the stability of the suspension and the influences of different deposition methods on the microstructures of the thick films were discussed. The result shows that dense thick films can be fabricated by stepwise deposition. The effect of different sintering temperatures to the dielectric constant and the dielectric loss of PNN-PZT thick films at room temperature were investigated. The dielectric constant and the dielectric loss at room temperature of the PNN-PZT thick film sintered at 1180°C for 30 min are 988 and 3.7% respectively. The electric induced displacement (E-D) curve and hysteresis loop of the PNN-PZT thick films were measured. The effective piezoelectric constant and the residual polarization of the PNN-PZT films are 90 pm/V and 6.00 kV/cm, respectively.

Effect of Sintering Temperature on Electrical Properties of ZnO Varistor Ceramics

To obtain ZnO varistors with high voltage gradient, ZnO varistors were fabricated by traditional ceramic sintering technique, the effect of different sintering temperature (1135～1155 °C) on electrical properties of ZnO varistors were investigated. The experimental results show that with increasement of sintering temperature, the grain size of ZnO varistor ceramic becomes bigger, the voltage gradient of varistor decreases and the density is improved. When the sintering temperature is at 1135 °C, the voltage gradient of varistor is up to 329V/mm, the leakage current is 8μA and the density is 96.4%. When the sintering temperature is at 1140 °C, the voltage gradient of varistor is 301V/mm, the leakage current is 4μA and the density is 96.6%. Compared the results at 1135 °C with 1140 °C , it is found that the comprehensive electrical properties of ZnO varistors reach maximum at 1140 °C.

Synthesis and electrochemical properties of LiNi0.5Mn1.5O4 as a 5 V cathode material for lithium ion batteries

LiNi0.5Mn1.5O4 as a 5 V cathode material for a lithium-ion battery was synthesized by solution evaporation process in this paper. Thermal gravimetric analysis of the precursor compounds was carried out. X-ray diffraction and scanning electron microscope were used for studying the structure and the morphology of the LiNi0.5Mn1.5O4 materials. Cyclic voltammograms and charge–discharge curves were obtained for presenting the electrochemical performances of LiNi0.5Mn1.5O4. Experimental results show that the discharge capacity and capacity retention of the LiNi0.5Mn1.5O4 prepared by solution evaporation process are superior to the LiNi0.5Mn1.5O4 obtained by melting salt method. The effects of different sintering temperatures on the electrochemical properties of the LiNi0.5Mn1.5O4 electrode materials synthesized by a solution evaporation process were also systematically investigated. With the raising of the sintering temperature, the size of the LiNi0.5Mn1.5O4 gradually increases, its crystallinity is enhanced and the surface morphology of grain is gradually neatened. Electrochemical test results show that the LiNi0.5Mn1.5O4 prepared at 800 °C has the best cycle reversibility, the highest discharge capacity and the optimal capacity retention.

Preparation of phosphate bonded silicon nitride porous ceramics in air

Silicon nitride porous ceramics were prepared using a new method by combining in-situ forming and low-temperature pressureless sintering in air, in which the Al(H2PO4)3 was used as the binder. The effects of the binder and curing agent content, as well as the temperature to the quality of the green body and setting time were investigated to establish the proper parameters of setting. The green body was sintered at low temperature (1000 − 1300 ˚C) in air. Then we discussed the phase transition during the sintering process and the effects of different sintering temperatures on the microstructure. The results showed that at 50 ˚C, a green body with nearly zero shrinkage and high strength was obtained after 30minutes of the slurry casted. At 1300 ˚C there was sufficient C-AlPO4 binder phase transformed from Al (H2PO4)3 to bond with the Si3N4 grains, leading to a good adhesion between them. Porous Si3N4 ceramics with a porosity of 46 − 48%, compressive strength of 30 − 50MPa were ultimately obtained.

Mechanical Properties and Oxidation Resistance of Hot Pressed B<sub>4</sub>C Ceramics Material

B4C ceramics were obtained using hot-pressing method. The effect of different sintering temperatures on the microstructures and mechanical properties of B4C ceramics were investigated. Oxidation resistances were studied over the range 600-850°C. The experimental results showed that the relative density, bending strength and fracture toughness all increased first and then decreased with increasing the sintering temperature. The Vickers-hardness increased as the sintering temperature increasing. When the sintering temperature was 1950°C, the B4C ceramics showed the optimized properties. The values of its relative density, Vickers-hardness, bending strength and fracture toughness were 99.1%, 34.0 GPa, 524.6 MPa and 6.56 MPa·m1/2, respectively.

High capacity anode materials for Li-ion batteries based on spinel metal oxides AMn2O4 (A = Co, Ni, and Zn)

Manganites of transition and/or post-transition metals, AMn2O4 (where A was Co, Ni or Zn), were synthesized by a simple and easily scalable co-precipitation route and were evaluated as anode materials for Li-ion batteries. The obtained powders were characterized by SEM, TEM, and XRD techniques. Battery cycling showed that ZnMn2O4 exhibited the best performance (discharge capacity, cycling, and rate capability) compared to the two other manganites and their corresponding simple oxides. Further studies on the effect of different sintering temperatures (from 400 to 1000 °C) on particle size were performed, and it is found that the size of the particles had a significant effect on the performance of the batteries. The optimum particle size for ZnMn2O4 is found to be 75–150 nm. In addition, the use of water-soluble and environmentally friendly binders, such as lithium and sodium salts of carboxymethlycellulose, greatly improved the performance of the batteries compared to the conventional binder, PVDF. Finally, ZnMn2O4 powder sintered at 800 °C (<150 nm) and the use of the in-house synthesized lithium salt of carboxymethlycellulose (LiCMC) binder gave the best battery performance: a capacity of 690 mA h g−1 (3450 mA h mL−1) at C/10, along with good rate capability and excellent capacity retention (88%).

Critical aspects of sinter-hardening of prealloyed Cr–Mo steel

In recent years, growing demand for greater mechanical properties of PM steel components with competitive fabrication cost has led to significant innovations in different fields of powder metallurgy. Recent research has been focused on reaching higher performance with lower cost. To this end, the possibility of combining the conventional sintering and post-sintering processes for a particular powder composition has been introduced. Sinter-hardening is a result of the research conducted along this line. Elimination of any secondary operation such as quench-hardening by incorporating it in the sintering process (i.e. sinter-hardening) is of great interest, as it will lead to lower processing costs and equal, if not higher mechanical performance. However, to ensure the desired mechanical properties of the final component and robustness of the performance, critical aspects of the sinter-hardening process should be rigorously studied. Hence with specific attention to a Cr–Mo steel powder (FL-5305), this study deals with the influence of density on cooling rate, the effect of different sintering temperatures (e.g. 1120 °C and 1250 °C) on austenite grain size and consequently, hardenability. The microstructure development in sinter-hardened FL-5305 material has been analyzed and predicted by means of the available literature for solid steel and also using the commercial software (JMatPro 5.0) for materials assessment based on thermodynamic and kinetics modeling. Finally, inaccurate carbon control and its adverse impact on excessive formation of cementite have been addressed.

PREPARATION OF CE0.8GD0.2O1.9 SOLID ELECTROLYTE BY THE SOL-COMBUSTION METHOD

ABSTRACT Ce 0.8 Gd 0.2 O 1.9 (GDC) powders were prepared by a novel sol-combustion method using citric acid as the chelating reagent. The effects of different sintering temperatures were investigated on the evolution of crystalline phase, particle size, and lattice parameters of the resulted GDC powders. The results have shown that ultrafine GDC powders of around 40nm in diameter were successfully prepared by the sol-combustion technique. The powders showed a high sinterability, and a relative of 95.2% of the theoretical density was obtained at a sintering temperature of 1250 o C. Electrochemistry measurements showed that the GDC ceramics had relatively high oxygen ionic conductivity in low-temperature range. Keywords: SOFC; Doped CeO 2 ; Electrical conductivity; Sol-combustion method; Electrolyte INTRODUCTION Solid oxide fuel cell (SOFC) is a new chemical energy source with many advantages, such as transformation of chemical energy to electrical energy with high efficiency and low pollution to environment

Studies on sintering of solid state synthesized Ba 1− xK xBiO 3− δ superconducting phase

Superconducting Ba 1− x K x BiO 3− δ pellets were synthesized by solid state reaction followed by sintering. Thermo-gravimetric and differential thermo-gravimetric analysis (TG–DTA) of the mixture of nitrates was carried out to study the reactions during the phase formation. The effect of different sintering temperatures on the phase formation was studied. The X-ray diffraction data confirms the formation of superconducting Ba 0.6K 0.4BiO 2.23 phase at 700 °C. The surface morphological studies as a function of sintering temperature were studied by SEM. It is observed that the pellets prepared by solid state reaction followed its sintering at 700°C shows the superconducting transition at 26.8 K.

Effects of different sintering temperature and Nb 2O 5 content on structural and magnetic properties of Z-type hexaferrites

Nb-doped Z-type hexaferrites (Ba 3(Co 0.4Zn 0.6) 2Fe 24O 41) with composition of Ba 3(Co 0.4Zn 0.6) 2Fe 24O 41+ x Nb 2O 5 (where x=0.0, 0.1, 0.2, 0.4, 0.6, 0.8, 1.2, 1.6 and 2.0 wt%) were prepared by a solid-state reaction method. The effects of different sintering temperature ( T s) and Nb 2O 5 content on the sintering behaviors, phase composing, microstructure, and magnetic properties of the samples were investigated. The results from X-ray diffraction and scanning electron microscopy show that as the amount of Nb 2O 5 additive increases, the major phase changes to Z-phase, Simultaneously, M-phase and a small amount of niobate phase appear. The Nb 2O 5 additive promotes the grain growth as reaction center at lower sintering temperature (1220 °C), but at higher temperature (1260 °C), niobate phase separated out in grain boundaries as secondary phase will restrain abnormal grain growth, so closed pores in grains are not formed. The Nb 2O 5 additive can enhance densification, improve initial permeability of hexaferrites by increasing the grain growth of hexaferrite and the displacement of ions in the sintering process due to the aberration and activation of crystal lattice, which is accompanied by the solubility of Nb 5+ in the hexaferrites. A relative density of 96%, maximum initial permeability (32–33), minimum coercivity (454–455 A/m) and resonance frequency above 400 MHz were obtained for the sample with 0.8 wt% Nb 2O 5 sintered at 1260 °C for 6 h.

Effects of different sintering temperature and Mn content on magnetic properties of NiZn ferrites

Mn-doped NiZn ferrites with compositions of Ni0.44Zn0.56MnxFe2−xO4 (where x=0.00, 0.05, 0.10 and 0.15) were prepared by conventional ceramic technology. The effects of different sintering temperature (Ts) such as 1180, 1220 and 1260°C and Mn content on magnetic properties of the above series of samples were investigated. Initial permeability μi increases with the increasing of Mn content at Ts=1220 and 1260°C, but decreases at Ts=1180°C. In addition, all Mn substituted ceramic samples especially sintered at 1220°C possess higher quality factor (Q factor) than the NiZn ferrites with no Mn content.

Particle mixing in nearly full horizontal rotating cylinders

In recent years, growing demand for greater mechanical properties of PM steel components with competitive fabrication cost has led to significant innovations in different fields of powder metallurgy. Recent research has been focused on reaching higher performance with lower cost. To this end, the possibility of combining the conventional sintering and post-sintering processes for a particular powder composition has been introduced. Sinter-hardening is a result of the research conducted along this line. Elimination of any secondary operation such as quench-hardening by incorporating it in the sintering process (i.e. sinter-hardening) is of great interest, as it will lead to lower processing costs and equal, if not higher mechanical performance. However, to ensure the desired mechanical properties of the final component and robustness of the performance, critical aspects of the sinter-hardening process should be rigorously studied.Hence with specific attention to a Cr–Mo steel powder (FL-5305), this study deals with the influence of density on cooling rate, the effect of different sintering temperatures (e.g. 1120 °C and 1250 °C) on austenite grain size and consequently, hardenability. The microstructure development in sinter-hardened FL-5305 material has been analyzed and predicted by means of the available literature for solid steel and also using the commercial software (JMatPro 5.0) for materials assessment based on thermodynamic and kinetics modeling. Finally, inaccurate carbon control and its adverse impact on excessive formation of cementite have been addressed.

Sintering studies of nanophase ceramic oxides using small angle scattering

The microstructure evolution during sintering of nanophase ceramics has been followed using small-angle neutron and X-ray scattering. These techniques enable material microstructure parameters and surface areas to be measured nondestructively, and have been applied to study the effects of different sintering temperatures, pressures and additives. Depending on the sintered density, the scattering data from nanophase materials exhibit Porod scattering associated with the high surface area, scattering from the nanometer-size grains and pores, and interparticle interference scattering. By using samples of sufficient size and uniformity to permit absolute calibration of the scattering data, it has been possible to develop a fully quantitative microstructure model. Studies of nanophase yttria (powder, prepared by Nanophase Technologies Corporation, Burr Ridge, IL) and zirconia (powder, prepared at Rutgers University, Piscataway, NJ) are discussed, and it is shown how small-angle scattering, in conjunction with density measurements, electron microscopy and X-ray diffraction, provides a unique probe of the statistically representative microstructures present in these novel materials.

Small-Angle Scattering Methods for Studying the Sintering of Nanophase Ceramic Compacts

ABSTRACTStudies of microstructure evolution as a function of sintering parameters are necessary to better control the microstructure of nanophase ceramic compacts during processing. Small-angle scattering provides a comprehensive probe of the statistically-representative microstructures present in nanophase ceramics. A complete characterization includes complementary density, electron microscopy, nitrogen desorption and x-ray diffraction measurements. Small-angleneutron and ultra-small-angle x-ray scattering have been used to determine the effects of different sintering temperatures, pressures and additives during sintering of nanophase zirconia compacts. The samples were of sufficient size and uniformity to permit absolute calibration of the scattering data, making it possible to confirm that scattering from the pore/grain interface dominates the total scattering cross-section. A quantitative microstructural model was developed for this system, resulting in the determination of specific pore surface area, total pore volume fraction, pore number size distribution and grain size as a function of sintering parameters.