Effect Of Sintering Atmosphere Research Articles

Effect of sintering atmospheres on printed silver nanoparticle patterns for flexible electronics application

Effect of sintering atmospheres on printed silver nanoparticle patterns for flexible electronics application

Green synthesis of porous SiC ceramics using silicon kerf waste in different sintering atmospheres and pore structure optimization

This work reported the feasibility of using silicon kerf waste as raw material for the preparation of porous SiC ceramics, as well as effects of sintering atmospheres and additives on the properties of as-prepared ceramics. Samples sintered in Ar, N2, and carbon embedded atmospheres exhibited entirely different properties because of the formed bonding phases of SiCw, Si3N4/Si2N2O, and Si2N2O. Moreover, the apparent porosity and closed porosity of the samples were increased with the additions of feldspar and starch. Preferably, a series of porous SiC ceramics with apparent/closed porosity of 24.15%–59.59%/5.83%–14.77%, bulk density of 1.13–1.91 g cm−3, cold compressive strength of 34.73–249.89 MPa, and thermal shock resistance of 110–118 cycles was synthesized at 1500 °C in carbon embedded atmosphere. Therefore, a low-cost and facile synthesis strategy for preparing high-quality porous SiC ceramics from solid waste is proposed in present study.

Effect of sintering atmospheres on the structure and properties of the 612 type barium-calcium-aluminate for the dispenser cathodes

Abstract The effects of air, hydrogen, and CO 2 and O 2 mixture sintering atmospheres on the structure, micromorphology, electron emission capability and environmental stability of 612 type barium-calcium-aluminates have been investigated. Both the 6BaO-1CaO-2Al 2 O 3 aluminates sintered in air and hydrogen crystallize in the Ba 3 CaAl 2 O 7 phase. However, the aluminates with the same composition sintered in CO 2 and O 2 mixture crystallizes in the Ba 3 Al 2 O 6 phase with a small amount of BaCO 3 reactant. The microstructure for the aluminates sintered in air and H 2 show similar features while the sample sintered in CO 2 and O 2 mixture atmosphere shows better conglomeration. Emissivity tests indicate that the divergent current density J div for the dispenser cathodes impregnated with aluminates sintering in air, H 2 , and CO 2 and O 2 mixture atmospheres are 6.0, 6.1, and 7.6 A cm −2 at 1130 °C B , respectively. Finally, environmental stability tests indicate that the aluminates with the Ba 3 CaAl 2 O 6 phase sintered in air as well as hydrogen is more environmentally stable than that with Ba 3 Al 2 O 6 phase sintered in CO 2 and O 2 mixture. The process of sintering 612 aluminate in CO 2 and O 2 mixture is beneficial for superior emissivity on the condition of avoiding exposure to moisture.

The effect of sintering atmospheres on the properties of CSBT-0.15 ferroelectric ceramics

Ca0.15Sr1.85Bi4Ti5O18 (CSBT-0.15) ferroelectric ceramics were developed by the conventional solid-state reaction method under various sintering atmospheres. The influences of these sintering atmospheres on grain orientation, grain size, oxygen vacancies, ferroelectric properties and leakage mechanisms were systematically investigated. It was found that the samples sintered under N2 showed higher a-axis orientation and smaller grain sizes than those sintered under O2 and air. From XPS analysis, it can be observed that the amount of Ti3+ in the ceramics sintered under N2 is relatively high, which indicates a high number of oxygen vacancies in these samples. The samples sintered under N2, air and O2 all delivered well-saturated hysteresis loops with a remnant polarization (2Pr) of 13.8 μC/cm2, 12.4 μC/cm2 and 7.2 μC/cm2 and corresponding coercive fields (2Ec) of 100 kV/cm, 86 kV/cm and 80 kV/cm, respectively. At 70 kV/cm, the leakage current densities of the samples sintered under N2, air and O2 are 4.2 × 10−6 A/cm2, 1.9 × 10−6 A/cm2 and 1.0 × 10−6 A/cm2, respectively. The leakage conduction mechanism transformed from Ohmic conduction in a relatively low applied electric field range (0–15 kV/cm) to space-charge-limited conduction (SCLC) in higher electric field ranges.

Effects of sintering atmospheres on thermoelectric properties, phase, microstructure and lattice parameters c/a ratio of Al, Ga dual doped ZnO ceramics sintered at high temperature

Thermoelectric properties, phase and microstructural investigation of (Zn1−x−yAlxGay)O, where x = 0.02, y = 0.04, 0.05 and x = 0.03, y = 0.01, 0.02 are studied at a high temperature of 1450 °C in this article. We have focused on the effects of sintering atmospheres on thermoelectric properties, phase, and microstructure in the air as well in the argon atmosphere. The Seebeck coefficient (S) and electrical resistivities (ρ) measured in air and argon atmospheres have an evidential large difference. The air sintered Al, Ga co-doped ZnO has higher power factor (S2σ) of the order 720.9 µW K− 2 m− 1 and lower electrical resistivity (ρ) of 5.803 mΩ cm for the nominal formula (Zn1− x−yAlxGay)O, with x = 0.03, y = 0.01 as compared to the power factor 543.6 µW K− 2 m− 1 and electrical resistivity of the order 1.550 mΩ cm at 692.2 °C sintered in the argon atmosphere at the same temperature i.e. 1450 °C. The power factor of the air sintered sample with x = 0.03, y = 0.01 is 1.4 times higher than the argon sintered sample with the same composition. The difference in power factors and electrical resistivities are linked to sintering atmospheres. We will investigate the effects of sintering atmospheres of the co-doped ZnO and will study thermoelectric properties, phase, and microstructures of the co-doped ZnO.

Effect of Sintering Atmospheres on the Processing of SiC/AlN Ceramic Composites

In an attempt to provide a new advanced carbide/nitride ceramic material with high sinterability and density for high-temperature and solar energy applications, this work inspected the effect of different sintering atmospheres on the processing of near-fully dense SiC/AlN ceramic composites. Several SiC/AlN (0 – 40 wt.%) composites were produced by pressureless sintering at a temperature of 2080°C for 2 hrs using a sintering additive of 2.5% yttria + alumina. Influences of argon/vacuum and nitrogen/vacuum atmospheres on the reaction response and the densification behavior of SiC/AlN composites were examined and analyzed. Results show that sintering of SiC/AlN ceramics in a nitrogen atmosphere increases mass loss of the different composites during sintering and leads to a decrease in their densification parameters. However, sintering in an argon atmosphere promotes both the sintering and densification processes, making argon atmosphere more convenient for sintering SiC/AlN ceramics. The use of SiC/AlN composites prepared by pressureless sintering is suitable for high-temperature applications.

Effects of sintering atmospheres on phase transformation, oxygen vacancy and photoabsorption behaviors of highly Fe-doped titania crystals

Fe-doped TiO2 crystals were successfully prepared using a sol–gel technique in reducing and oxidizing atmospheres. The effects of sintering atmosphere on phase transformation, oxygen vacancy concentration and photoabsorption behaviors were investigated. The results indicate that upon sintering in reducing atmosphere, Ti and Fe ion valences were decreased and highly Fe ions (12 mol%) were entirely dissolved into titania crystals, increasing oxygen vacancy concentration and leading to increased photoabsorption capability. In contrast, sintering in oxidizing atmosphere causes precipitation of the Fe2O3 phase, which is detrimental to the photoabsorption capability. The best photoabsorption performance is obtained by sintering 12 mol% Fe-doped TiO2 in reducing atmosphere, resulting in an absorption edge of approximately 435 nm, which is much higher than that of undoped TiO2 in the oxidizing atmospheres with the absorption edge 352 nm.

Effect of sintering atmosphere on the grain growth and hardness of SiC/polysilazane ceramic composites

Silicon carbide (SiC) monoliths were synthesised using nano-size SiC powder mixed with/without polysilazane by hot pressing at 1750°C for 1 h under an applied pressure of 20 MPa in N2 or Ar atmosphere. The effects of polysilazane and sintering atmosphere on the microstructure and hardness of SiC were examined. The grain sizes of the SiC ceramics sintered in N2 atmosphere with and without the polysilazane were 161 and 605 nm, while the density for those samples were 96.5 and 98.1%, respectively. It was shown that Si2N2O was formed for the SiC/polysilazane composite and sintered in N2. In addition, the sample mixed with polysilazane followed by sintering in N2 atmosphere revealed a quite high hardness in spite of its relatively low density. It was suggested that Si2N2O phase played an important role for the inhibition of grain and subsequent high hardness.

Effects of sintering atmospheres on properties of stainless steel porous hollow fiber membranes

Stainless steel (SS) is one of excellent materials for fabrication of hollow fiber membranes because of its good mechanical property. Phase inversion technique is a promising method for preparation of SS hollow fibers. The sintering step is critical for controlling the quality of SS hollow fibers by removal of organic additives and activation of particle binding. In this work, we prepared SS porous hollow fiber membranes by combined dry-wet spinning and sintering technique. The influence of sintering atmosphere (air, CO2, N2, He and H2) on microstructure and properties of SS hollow fibers were investigated extensively. It was found that air and CO2 could lead to metal oxidation while inert atmospheres (He and N2) caused carbon remaining in SS hollow fibers. By contrast, H2 atmosphere was effective in removing organic additives without metal oxidation. High mechanical strength could be achieved for the hollow fiber membranes sintered in H2 atmosphere. At 1100°C for 1h, the as-sintered SS hollow fiber showed high bending strength of >200MPa and nitrogen permeance up to 9.5×10−5mols−1m−2Pa−1.

Greatly reduced leakage current and defect mechanism in atmosphere sintered BiFeO3–BaTiO3 high temperature piezoceramics

In current work, the effect of sintering atmospheres (N2, air and O2) on the structure, electrical properties, and defect mechanism of 0.8BiFeO3–0.2BaTiO3 lead-free piezoelectric ceramics has been investigated. X-ray diffractometer results indicated all the samples crystallized into the rhombohedrally distorted perovskite structure which was independent on the sintering atmospheres. Bi-containing impurity phases were observed in N2 sintered samples while not appearing in other atmospheres. X-ray photoelectron spectrum analysis indicated more Fe2+ ions, which can result in high leakage current, were involved in N2 sintered ceramics than that in O2- and air sintered compositions. However, greatly reduced leakage currents were obtained in N2 sintered ceramics which should be ascribed to the formation of secondary phases. The largest polarization and lowest leakage current were obtained in the sample sintered in N2 (2 h), which owned the optimal ferroelectric, piezoelectric, and electromechanical properties with piezoelectric constant d 33 = 98 pC/N, planar electromechanical coupling factors k p = 26.1 %, remnant polarization P r = 25.7 µC/cm2, coercive field E c = 74.6 kV/cm, and a high Curie temperature T c = 632 °C, respectively.

Effects of Sintering Conditions on Properties of a Warm Compacted Stainless Steel Powder

Effects of Sintering atmosphere and temperature on properties of warm compacted 410L stainless steel powder were studied. Sintered density, hardness, tensile strength and elongation were measured. Results showed that in order to achieve high comprehensive properties, the optimal sintering temperature was 1230°C for 410L stainless steel powder. At the same sintering temperature, density and hardness sintered in vacuum were much higher than that sintered in cracked ammonia while tensile strength sintered in cracked ammonia were much higher than that in vacuum. When sintered in vacuum at 1230°C, sintered density was 7.45 g•cm-3, hardness was 65 HRB, tensile strength was 410 MPa and elongation was 29.5%. When sintered in cracked ammonia atmosphere at 1230°C, sintered density was 7.26 g•cm-3, hardness was 97 HRB, tensile strength was 515 MPa and elongation was 3.8%.

Effect of sintering atmospheres on the densification behavior of CuO ceramics

In this study, the effect of oxygen partial pressure on the densification and the resultant microstructure change of CuO were examined. When CuO green bodies were heated up to 1100°C for sintering in air, denser CuO samples were obtained than the samples sintered in oxygen. When the samples were kept at 1100°C for a prolonged period of time, however, the densification of the sample in oxygen was accelerated whereas that of the sample in air was hindered. This is attributed to the phase transformation from CuO to Cu2O which accompanies oxygen release during sintering in air. On the basis of the results, dense CuO samples could be obtained by switching the sintering atmosphere from air to oxygen at the suitable stage so that oxygen release by reduction could be suppressed.

Effect of sintering atmosphere and lithium ion co-doping on photoluminescence properties of NaCaPO4:Eu2+ phosphor

This paper reports on the photoluminescence properties of Na1−yLiyCa1−xPO4:xEu2+ phosphors synthesized by a solid state reaction method. The prepared phosphors have been thoroughly characterized by means of X-ray diffraction (XRD), Field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectrum (FTIR), Raman spectrum, Thermo gravimetric and differential thermal analysis (TG–DTA) and photoluminescent spectral measurements. The structure of Na1−yLiyCa1−xPO4:xEu2+ phosphors were found to be orthorhombic in nature with a sphere-like morphology and having the particle size in micrometer range. The excitation spectra of NaCaPO4:Eu2+ phosphors revealed a broad excitation band having its maximum intensity at 373nm and ranging from 250m to 450nm. Incidentally, it matches well with the ultraviolet (UV) radiation of light-emitting diodes (LEDs). Upon 373nm excitation, these phosphors exhibited intense bluish-green emission band centered at 505nm. The effect of sintering atmospheres and co-doping of lithium ions on the photoluminescence properties of the NaCaPO4:Eu2+ phosphors were studied and explained suitably. The obtained results indicate that the prepared NaCaPO4:Eu2+ phosphors are promising bluish-green candidates for the phosphor-converted white LED applications.

Micro fabrication of stainless steel micro components using soft moulding and aqueous slurry

Presented is a fabrication process of stainless steel micro components. The fabrication process is divided into two main parts. In the first part, high quality SU-8 master moulds and their negative replicas from soft moulds are produced using photolithography and soft moulding techniques, respectively. The second part includes preparation of stainless steel slurry, filling the soft mould, obtaining the green parts, de-binding and sintering to the finial parts. The metallic slurry is investigated in details and the optimum dispersant and binder are obtained. Two different sintering conditions are investigated, vacuum and forming gas atmospheres. The effect of sintering atmospheres and temperatures on both density and linear shrinkage of the micro components are studied in details. The results show high quality micro components the same quality as the master moulds. The maximum sintered density and linear shrinkage are obtained when the samples are sintered in vacuum at 1350 °C and found to be 98.1% and 17.97%, respectively. The surface roughness of the sintered micro components is also investigated.

Effects of sintering atmospheres on sintering behavior, electrical conductivity and oxygen permeability of mixed-conducting membranes

Effects of sintering atmospheres on properties of SrCo 0.4Fe 0.5Zr 0.1O 3− δ mixed-conducting membranes were in detail studied in terms of sintering behavior, electrical conductivity and oxygen permeability. The sintering atmospheres were 100% N 2, 79% N 2–21% O 2, 60% N 2–40% O 2, 40% N 2–60% O 2, 20% N 2–80% O 2 and 100% O 2 (in vol.%), and the prepared membranes were correspondingly denoted as S-0, S-21, S-40, S-60, S-80 and S-100, respectively. It was found that the properties of membranes were strongly dependent on the sintering atmosphere. As the oxygen partial pressure in the sintering atmosphere ( P O 2 ) increased, sintering ability, electrical conductivity and oxygen permeability decreased at first, which was in the order of S-0 > S-21 > S-40. However, as P O 2 increased further, sintering ability, electrical conductivity and oxygen permeability increased gradually: S-40 < S-60 < S-80 < S-100. And the S-100 membrane had the best sintering ability, electrical conductivity and oxygen permeability in all membranes.

Effect of sintering atmospheres on the microstructure and dielectric properties of Yb/Mg co-doped BaTiO3 ceramics

The effect of Yb/Mg co-doping on the microstructure and electrical properties of BaTiO3 ceramics sintered under oxidizing, reducing and annealed conditions was investigated. XRD analyses indicated the suppression of the solubilities of the acceptor ions in BaTiO3 under the reducing and annealed conditions. DSC measurements indicated that addition of too much Yb would cause the collapse of the core-shell structure in the BaTiO3 ceramics. The effect of sintering atmospheres on the microstructure and dielectric properties was attributed to the change of the solubilities of the acceptor ions in this core-shell-structured material.

Effect of sintering atmospheres on structure and properties of copper alloys: S.Gheorghe, S.Sever. (University of Craiova, Craiova, Romania.)

Effect of sintering atmospheres on structure and properties of copper alloys: S.Gheorghe, S.Sever. (University of Craiova, Craiova, Romania.)

The effect of processing variables on the mechanical and electrical properties of barium titanate positive-temperature-coefficient-of-resistance ceramics

The effect of sintering atmospheres on the mechanical and electrical properties of four formulations of n-doped barium titanate PTCR ceramics has been investigated. Under sintering atmospheres with an oxygen partial pressure greater than 0.2 bar, it was found that the PTCR effect was unchanged up to a 100% oxygen atmosphere. Similarly mechanical strength, (measured by diametral compression and four-point bending of beams) and fracture toughness were little changed. However, at lower oxygen partial pressures, PTCR effects were reduced. The change in resistance was reduced from three orders of magnitude to one order of magnitude for one formulation

The effect of processing variables on the mechanical and electrical properties of barium-titanate positive-temperature-coefficient-of-resistance ceramics

The effect of sintering atmospheres on the mechanical and electrical properties of four formulations ofn-doped barium titanate PTCR ceramics has been investigated. Under sintering atmospheres with an oxygen partial pressure greater than 0.2 bar, it was found that the PTCR effect was unchanged up to a 100% oxygen atmosphere. Similarly mechanical strength, (measured by diametral compression and four-point bending of beams) and fracture toughness were little changed. However, at lower oxygen partial pressures, PTCR effects were reduced. The change in resistance was reduced from three orders of magnitude to one order of magnitude for one formulation. The corresponding strength and fracture toughness (measured by pure bending of small beams) were also significantly reduced from 83 MPa to 48 MPa and 1.0 MPa m1/2 to 0.35 MPa m1/2, respectively.

二酸化ウラン燃料の活性化焼結, (I)

The effect of sintering atmospheres and additives on the sintering rate and grain growth of UO2 were examined.Main results were summarized as follows.(1) Vacuum atomosphere accelerates the sintering rate of UO2 powder. It would be mainly due to the acceleration of diffusion phenomena by the presence of excess oxygen ion, and partially due to the vaporization and condensation near the surface of UO2 particles and open pores.(2) TiO2 addition pronouncedly accelerates the sintering rate and grain growth of UO2 powder, because TiO2 (or lower oxide of Ti) locally formes an eutectic of low melting point with UO2 and it accelerates the diffusion of oxygen ion.(3) BeO and Al2O3 are not soluble in UO2, and these minute addition (0.010.03%) are able to accelerate the sintering rate of UO2.Eutectic points of UO2-BeO, and UO2-Al2O3 systems are very high and cross sections of thermal neutron absorption are very low.So, both BeO and Al2O3 are considered to be desirable additives.(4) Al2O3 improves the stoichiometry of UO2, but it delays the sintering rate of UO2 in vacuum.