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In this study, the electrical conductivity of SmBaCo2O5+d (SBCO) is measured and analyzed with respect to the microstructure of the analyzed samples. The microstructure is influenced by the sintering temperature and by the precise composition of the composite cathode. Difference in the electrical conductivity at different applied current is investigated. The value of the electrical conductivity of SBCO sintered at 1150 °C was about 1024 S/cm at 600 °C, which was the highest compared to other samples sintered at lower temperatures. The electrical conductivities of porous microstructural SBCO sintered at 1150 °C with an addition of 10 wt% carbon black and of a composite cathode comprised of SBCO and Ce0.9Gd0.1O2 (CGO91) at a ratio of 1.9:0.1 were 256 and 525 S/cm at 600 °C. The electrical conductivities of SBCO samples increase when relatively low currents are applied. This trend can be observed at all pure SBCO and samples mixed with carbon black. However, these properties are not found in composite cathodes comprised of SBCO and CGO91.

The plume flow and radiative base heating of a solid rocket have been important factors for rocket survivability in the modern battlefield, in which the standard of technology determines the dominant position. To enhance rocket survivability and reduce base heating, infrared (IR) signatures emitted from an exhaust plume should be determined. In this work, therefore, IR signatures and radiative base heating characteristics in the plumes exhausted from a solid rocket operating at Mach number of 1.6 and altitudes of 5 km and 10 km, respectively, are numerically examined to find the physics related to the plume flow and radiative characteristics. The plume flow and radiative characteristics are obtained using a pre-conditioning method and weighted sum of gray gases model (WSGGM) coupled with finite volume method for radiation, respectively, and the IR signature at each location is post-processed with the narrow band-based WSGGM after plume fields are developed. After validating models adopted in this work by comparing with other solutions, the plume flow field, IR signature, and radiative base heating characteristics are investigated by changing such various parameters as altitude and particle concentrations in the exhaust plume. As a result, it is found that the particular wavelength IR signature level has high spectral characteristics because of $$ \text{CO}_{2} $$ and $$ \text{H}_{\text{2}} \text{O} $$ behaviors in the plume, and the radiative heat flux coming into the base plane decreases with higher flight altitude and longer distance from the nozzle exit.

The self-assembly behavior of 1,3:2,4-dibenzylidene-D-sorbitol (DBS) in ternary solvents has been systematically investigated for the use of kerosene gel in the aerospace propulsion. DBS forms a yield viscoelastic gels in a wide range of kerosene/hexanol/DMSO solvent concentrations despite the fact that DBS is incapable of gelling kerosene fuel. The gelation behavior of DBS in the solvent mixture is predicted using the Hansen solubility parameters. The polar parameter (δP) and hydrogen bonding (δH) parameter lie in the range of 1.96 ≤ δP ≤ 4.30 J0.5cm−1.5 and 3.40 ≤ δH ≤ 7.30 J0.5cm−1.5 respectively for the formation of gel in kerosene/hexanol/DMSO system. The phase transition temperature (Tf) of DBS gel is determined using temperature sweep measurement and predicted using modified Friedrich (MF) relation which is found be in close agreement with an average deviation of ± 10 °C. However, the deviation becomes larger when δP > 4.30 and δH > 7.30, in other words, with increase in the solvent polarity. As the solvent polarity or concentration of hexanol increases in the mixture, the gels exhibit a low Tf and $$ {G}_{max}^{\prime } $$ value because of the hindrance of self-assembling ability of DBS due to the intermolecular hydrogen bonding between DBS and solvents. The viscoelastic behavior of DBS gels is investigated using the oscillation sweep measurements and the storage modulus G′ is found to be higher than the loss modulus G″ for larger stress amplitude and frequency, indicating a solid-like nature of the gels. Furthermore, the microstructure analysis shows the presence of 3D nano-fibrillar morphology, which further depends on the solvent polarity. Microstructure changes from ‘rope-like’ fiber aggregate (Hex100; CH = 88 wt%) to a ‘web-like’ structures (Hex25; CH = 25 wt%), when the CH is decreased in the solvent mixture.

In this study, experiments were conducted to investigate the combustion characteristics of an water-in-oil W/O emulsion droplet under elevated temperature and pressure conditions. The base fuel used was n-decane, and total volume ratios of 10, 20, and 30% of distilled water were mixed for producing the emulsion fuel. Span 80 with a volume ratio of 2% was added as a surfactant, and the emulsion fuel was homogeneously mixed via ultrasonication. The combustion process of an emulsion droplet was divided into five stages: droplet heating, classical combustion, puffing, secondary classical combustion, and surfactant combustion. The ignition delay decreased with elevated ambient temperatures, whereas an increase in the ambient pressure and water volume ratio resulted in longer ignition delays. The droplets did not ignite in 500 °C or 600 °C conditions at 1 bar because of the significant Stefan flow of fuel vapor. After droplet ignition, the droplet combustion process, including classical combustion, puffing, and surfactant combustion, followed. The average burning rate increased with ambient pressure, but it was insensitive to ambient temperatures and water volume ratios. After flame extinction, a secondary flame reappeared because of the combustion of surfactant and residues.

In this study, electrochemical properties of layered perovskites having non-stoichiometric compositions (Sm1−xBaCo2O5+d, x = 0, 0. 01, 0.02, 0.03, 0.04, 0.05, 0.10, and 0.15) were analyzed for the direct application of cathode materials for Intermediate Temperature-operating Solid Oxide Fuel Cells (IT-SOFC). From the Sm1−xBaCo2O5+d oxide systems calcined at 1,100°C for 8 h, single phase (SmBaCo2O5+d, SBCO_1) was maintained only in the case of the x = 0 composition. In the compositions of x = 0.05–0.10, BaCoO2.6 was mixed with the pattern of SBCO. In addition, in the composition of x = 0.15, it was confirmed that BaCoO2.6 and CoO phases coexisted with SBCO. In the compositions of Sm1−xBaCo2O5+d, the overall Area Specific Resistance (ASR) values decreased as the removal amount of Sm increased from x = 0–0.10; then, the values increased for compositions from x = 0.15. For example, the ASRs of SBCO_1, Sm0.95BaCo2O5+d (SBCO_0.95), Sm0.90BaCo2O5+d (SBCO_0.90), and Sm0.85BaCo2O5+d (SBCO_0.85) measured at 600°C were 0.301, 0.147, 0.119, and 0.179 Ω cm2, respectively. In particular, SBCO_0.90 was found to have an excellent ASR property of about 0.035 Ω cm2 at 700°C. Typical properties of the metal–insulator transition (MIT) electrical conductivity were shown in all measured compositions. The temperature at which MIT occurred increased as the non-stoichiometric composition increased.

In SmBa1-xCaxCo2O5+d (x = 0.01, 0.03, 0.1, and 0.2, SBCCO) oxide systems calcined at 1100°C for 8 h, the XRD patterns of the SBCCO single phase were maintained in the cases of SmBa0.97Ca0.03Co2O5+d (SBCCO-0.97) and SmBa0.99Ca0.01Co2O5+d (SBCCO-0.99) compositions. In SmBa0.8Ca0.2Co2O5+d (SBCCO-0.8) and SmBa0.9Ca0.1Co2O5+d (SBCCO-0.9), CaCoSmO4 existed with the pattern SBCCO. SBCCO structures were identified as orthorhombic crystal structures because they showed splitting of the X-ray diffraction (XRD) peaks at 23.4°, 47.9°, and 59.1°.Typical metallic conduction behaviors were found in all measured compositions except SBCCO-0.8, which showed a metal-insulator transition (MIT) behavior. Compared to other SmBa1-xCaxCo2O5+d compositions, SBCCO-0.8 showed the highest electrical conductivity of 460 S/cm at 500°C. In particular, SBCCO-0.9 was found to have an excellent ASR characteristic of about 0.077 Ωcm2 at 700°C. The activation energy of SBCCO-0.9 was the lowest among SBCCO oxide systems with a value of 0.77 eV.

In SmBa1-xCaxCo2O5+d (x = 0.01, 0.03, 0.1, and 0.2, SBCCO) oxide systems calcined at 1100°C for 8 h, the XRD patterns of the SBCCO single phase were maintained in the cases of SmBa0.97Ca0.03Co2O5+d (SBCCO-0.97) and SmBa0.99Ca0.01Co2O5+d (SBCCO-0.99) compositions. In SmBa0.8Ca0.2Co2O5+d (SBCCO-0.8) and SmBa0.9Ca0.1Co2O5+d (SBCCO-0.9), CaCoSmO4 existed with the pattern SBCCO. SBCCO structures were identified as orthorhombic crystal structures because they showed splitting of the X-ray diffraction (XRD) peaks at 23.4°, 47.9°, and 59.1°.Typical metallic conduction behaviors were found in all measured compositions except SBCCO-0.8, which showed a metal-insulator transition (MIT) behavior. Compared to other SmBa1-xCaxCo2O5+d compositions, SBCCO-0.8 showed the highest electrical conductivity of 460 S/cm at 500°C. In particular, SBCCO-0.9 was found to have an excellent ASR characteristic of about 0.077 Ωcm2 at 700°C. The activation energy of SBCCO-0.9 was the lowest among SBCCO oxide systems with a value of 0.77 eV.

In this study, the chemical states of a powder type and an impregnated type of the La0.4Sr0.6Ti0.8Mn0.2O3±d (LSTM) oxide system were investigated along with its electrical conductivities in order to apply these materials as alternative anode materials for high temperature-operating Solid Oxide Fuel Cells (HT-SOFCs). The Ni/8YSZ samples with LSTM impregnated into the pores created by partially removing nickel, Ni/8YSZ (Ni (R)/8YSZ), showed much higher electrical conductivity values than those of unimpregnated Ni/8YSZ (Ni (E)/8YSZ) samples under dry H2 fuel condition. Reduction of Mn4+ to Mn3+ was observed when LSTM was reduced. Additional reduction properties of Mn2+ from Mn3+ and satellite peaks were found when impregnated LSTM was coated onto a Ni/8YSZ substrate. The reduction of the charge state of Ti contained in LSTM showed the same behavior as the reduction property of Mn. However, a satellite peak identified as metal Ti was only observed when impregnated LSTM was coated on a selectively Ni-removed Ni/8YSZ (Ni (R)/8YSZ) substrate.

The evaporation characteristics of water/n-decane emulsion droplet at various temperatures and pressures were experimentally observed. Emulsion fuel was made by adding pure water to the base n-decane fuel with a volume ratio of 0.2. Span 80 was used as a surfactant, and ultrasonification was conducted for the mixing process. The temporal variation of the droplet diameter was optically observed by using a high-speed camera, and the changes in droplet temperature were also measured. The evaporation process of emulsion droplets was divided into three stages, namely, droplet heating, inflation/puffing, and pure evaporation. As the ambient temperature increased, the behavior of droplet inflation shifted to puffing during the inflation/puffing stage. A decline in the inflation/puffing incidence rate was noted at high-pressure conditions. The evaporation rate during the pure evaporation stage and the overall droplet lifetime were affected by the ambient temperature but not by the ambient pressure. The inflation of the droplet mostly occurred at relatively lower temperature and pressure conditions; it changed to puffing, however, at higher temperature and pressure conditions.

In this study, the microstructural and electrochemical properties of linear type nanofibers obtained by adding SmBa0.5Sr0.5Co2O5+d (SBSCO) layered perovskite oxide were investigated for use as cathode materials in a low temperature-operating solid oxide fuel cell. Linear type SBSCO fiber and Ce0.9Gd0.1O2−d coated SBSCO-fiber were fabricated using the electrospinning process. It was confirmed that the area specific resistance (0.75 Ω cm2) of the obtained SBSCO-fiber cathode was much lower than that (1.25 Ω cm2) of a powder-type SBSCO cathode at 550 °C. The result shows that the SBSCO fiber cathode exhibits lower polarization resistance in low temperature ranges than the powder SBSCO cathode materials do. A significantly lower activation energy (0.76 eV) was observed in fiber SBSCO cathode than in the nanostructured La0.8Sr0.2Co0.2Fe0.8O3−d ones which were used as control at 1.53 eV.

In this study, phase synthesis and electrochemical properties of Sm1-xNdxBa0.5Sr0.5Co2O5+d (x = 0–0.9) oxide systems where neodymium and samarium were replaced at the A-site of SmBa0.5Sr0.5Co2O5+d layered perovskite are investigated for use as cathode materials in Intermediate Temperature-operating Solid Oxide Fuel Cells (IT-SOFCs). The structure of Sm1-xNdxBa0.5Sr0.5Co2O5+d (x = 0–0.9) oxide systems can exist in either an orthorhombic (x = 0–0.4) or tetragonal (x = 0.5–0.9) form. The maximum electrical conductivities in Sm1-xNdxBa0.5Sr0.5Co2O5+d (x = 0–0.9) oxide systems were obtained from Sm0.2Nd0.8Ba0.5Sr0.5Co2O5+d (SNBSCO8) and their values are 1280 and 280 Scm−1 at 50 °C and 900 °C, respectively. The area specific resistances (ASRs) of SBSCO are 3.019, 0.611, and 0.092 Ωcm2 at 500, 600, and 700 °C, respectively. However, SNBSCO8 single phase gives the lowest ASRs of 1.751, 0.244 and 0.044 Ωcm2 at the same temperatures tested. SNBSCO8 is thus a promising candidate cathode material for IT-SOFC applications.

The hydrogen-trap states in TiC and MoC that have coherent interfaces with ferrite were investigated using first-principles calculation. The trapping sites of TiC were the interfaces and interstitial sites of ferrite. On the other hand, the trapping sites of MoC were ferrite interstitial sites; the interface had a negative binding energy with H. Thermal desorption analysis confirms that the amounts of diffusible hydrogen were significantly reduced by addition of Mo in Ti-bearing steel.

This study reports first findings on the solidification of eco-friendly ethanol fuel by organic gellant, namely, Methylcellulose (MC) and Hydroxypropyl methylcellulose (HPMC) for use as a solid fuel for the hybrid propulsion system. Specifically, the rheological properties of solidified ethanol are determined using both shear flow tests and dynamic oscillation tests for the gellant concentration varying in the range of 5 wt% to 17 wt% and nanoparticle loading varying in the range of 2 wt% to 6 wt% for HPMC and 2 wt% to 4 wt% for MC samples respectively. It is observed that over the range of applied shear rate (0.1–1000 s−1) solidified ethanol fuels exhibit a strong shear thinning, high yield thixotropic behavior. The yield stress of the fuel sample ranges from 424.20–1252.40 Pa, and found to the direct function of type, concentration of gellant and nanoparticle loading. Below the yield stress, the solid samples exhibit an elastic dominant behavior ( G ′ > G ″ ) and found to be independent of applied stress in the linear viscoelastic region. In dynamic tests, the spectra of G ′ ( ω ) and G ″ ( ω ) indicates that solidified ethanol forms a covalently cross-linked network between ethanol-water blend and gellant material. A key finding of this study reveals that all ethanol fuel formulations display solid-like characteristics under test conditions as G ′ and G ″ are nearly independent of the frequency and the magnitude of G ′ is 4.1–5.4 times higher than G ″ . Finally, the effect of gellant type on rheological behavior is studied where it is observed that the relative thixotropic area and creep strain of HPMC laden fuels is significantly higher compared to their MC counterparts which imparts them a viscous dominant character.

In this study, the phase synthesis and electrochemical properties of A/A//A///B2O5+d (A/: Lanthanide, A//: Ba, and A//: Sr) layered perovskites in which Pr and Sm were substituted at the A/-site were investigated for cathode materials of Intermediate Temperature-Operating Solid Oxide Fuel cells (IT-SOFC). In the PrxSm1-xBa0.5Sr0.5Co2O5+d (x = 0.1–0.9) systems, tetragonal (x &lt, 0.4) and orthorhombic (x ≥ 0.5) crystalline structures were confirmed according to the substitution amount of Pr, which has a relatively large ionic radius, and Sm, which has a small ionic radius. All of the layered perovskite oxide systems utilized in this study presented typical metallic conductivity behavior, with decreasing electrical conductivity as temperature increased. In addition, Pr0.5Sm0.5Ba0.5Sr0.5Co2O5+d (PSBSCO55), showing a tetragonal crystalline structure, had the lowest conductivity values. However, the Area-Specific Resistance (ASR) of PSBSCO55 was found to be 0.10 Ωcm2 at 700 °C, which is lower than those of the other compositions.

The aim of this research is to investigate the effects of a direct current (DC) electric field on the combustion behavior of a co-flow propane diffusion flame. The flame length and NOx emission were observed and measured. The electric field enhances the combustion process of propane diffusion flame by causing the movement of ions and molecules in the flame, resulting in a change in the shape of the flame. The flame heights decrease with an increase in the applied voltage and polarity, a more dominant effect to be observed with a positive DC electric field. However, for the applied negative polarity, the inner-cone of the propane diffusion flame is shifted by the electric field. Drastic reduction in the NOx emission is observed with an increase in the applied DC voltage and polarity. In the existing system, the reduction percentage of NOx is within the range of 55 to 78%.

Effects of hydrogen on the mechanical properties and fracture patterns of nano-sized yttria (Y 2 O 3 ) dispersed 316L austenitic steel usually mentioned as oxide dispersed strengthened (ODS) steel was studied from in situ tensile test using small specimens under high-pressure hydrogen gas, and the steel’s hydrogen desorption properties were quantified using thermal desorption spectra analysis. The steel samples were prepared using powder metallurgy from precursor powders with 5 μm and 150 μm particle size, then processed by mechanical alloying and hot isostatic press. The original powder size affected mechanical properties and hydrogen embrittlement. Type-316L ODS steel with fine grain size showed the robust tensile property under gaseous hydrogen and less hydrogen susceptibility. Yttria-doped 316L steel is a candidate for use as a structural component exposed to hydrogen in nuclear fusion reactors, so these results will be useful to material and component design criteria.

An experimental investigation on achieving hypergolicity with a critical catalyst concentration and measuring ignition delay of non-metalized and metalized gelled ethanolamine was performed with hydrogen peroxide as an oxidizer. The experimental results of using high speed camera were obtained by adopting the drop tests in this work. This study represented a sufficient repeatability of ignition delay for hypergolic bipropellant system. Gelled ethanolamine fuel (non-metalized and metalized with nano-sized metal particle substitution) with metal catalysts presented the results in hypergolicity with ignition delays of the order of 1–5 ms in most of the cases, which was comparable to the existing liquid hypergolic bipropellant systems. However, the minimum ignition delay time was recorded for pure-CCAT case. Moreover, the calculated activation energy (Evis) for the gelled ethanolamine fuel for non-metalized and metalized systems was within the range of 0.03–0.06 kJ/mole along with shear thinning behavior. Parameters such as apparent viscosity of the fuels, blended energetic particle, catalyst type along with its critical concentration using the drop impact plays an important role in studying the hypergolicity and ignition delay time of the gel bipropellant.

Non-toxic hypergolic propellants have considerably generated recent research interest in the field of green propulsion technology because they can replace highly toxic hypergolic combinations currently used. In this experimental research, sodium borohydride-based non-toxic hypergolic fuel was prepared by blending sodium borohydride in the mixture of energetic hydrocarbon solvents. In a drop test, sodium borohydride as an ignition source enabled the hydrocarbon mixture to initiate hypergolic interactions with H 2 O 2 oxidizer. Two different heating methods were utilized to analyze the characteristics of autoignition and combustion of the hypergolic fuel. As a reference fuel, a non-hypergolic fuel which has the identical chemical compositions to the hypergolic fuel except for sodium borohydride was tested and compared. As a one of the heating methods, thermogravimetric analysis was not suitable for evaluating the inherent thermophysical properties of the hypergolic fuel. In a droplet combustion chamber test, the autoignition and combustion of the hypergolic fuel droplets occurred exposed to elevated temperatures (in a range of 400–800 °C) at atmospheric pressure (1 bar), whereas the non-hypergolic fuel droplet was automatically ignited only at 800 °C. The ignition delay and total combustion time of the hypergolic fuel droplet were lower than those of the non-hypergolic fuel droplet. According to the temporal histories of the droplet size, sodium borohydride-based hypergolic fuel droplets did not obey the d 2 -law of diffusion-controlled combustion, which indicates the droplet evaporation rate was not a controlling factor in the combustion process. Consequently, the addition of sodium borohydride into the hydrocarbon mixture expedited the autoignition and combustion process of the fuel at elevated temperatures.

This paper reports simulation and evaluation of the magnetic flux density (MFD) of a rotating Halbach magnet (RHM) composed of a rotating inner Halbach cylinder (HC) and a fixed outer HC. We first chose the dimension of a single HC, then determined the dimensions of an inner and outer HC to get MFD = 2 T. Simulation results were used to guide fabrication of an RHM; its magnetic field in the central axis direction agreed well with simulated values.

The effect of high-pressure gaseous H2 on the fracture behavior of pipeline steel X70 and austenitic stainless steel type 304L and 316L was investigated by means of notched-tensile tests at 10 MPa H2 gas and various test speed. The notch tensile strength of pipeline X70 steel and austenitic stainless steels were degraded by gaseous H2, and the deterioration was accompanied by noticeable changes in fracture morphology. The loss of notch tensile strength of type 316L and X70 steels was comparable, but type 304L was more susceptible to hydrogen embrittlement than the others. In the X70 steel, hydrogen embrittlement increased as test speed decreased until the test speed reached 1.2 × 10−3 mm/s, but the effect of test speed was not significant in 304L and 316L steels.

Metal additive manufacturing (AM) technology as the emerging future manufacturing technology can be applied to the hydrogen service including hydrogen energy utilized industry. Direct metal tooling (DMT), one of the 3-D printing technologies, was used to manufacture an austenitic stainless steel part, and its mechanical properties and hydrogen embrittlement (HE) behavior were studied using the small specimen test technique under 10-MPa pressurized hydrogen gas. This part showed high HE resistance with minimal strain-induced transformation of austenite to martensite. This result indicates that parts produced using DMT are suitable for use in facilities for hydrogen service and hydrogen infrastructure.

An experimental study of hypergolicity and ignition delay of pure and energized gelled ethanol with hydrogen peroxide was carried out. Experimental drop test results were obtained and discussed by using Photron high speed camera imaging. This study represented a sufficient repeatability of ignition delay for hypergolic gel bipropellant development. Gelled ethanol fuel (pure and energized with nano-Al/B/C particle substitution) mixture with metal catalysts were formulated to examine its hypergolicity with ignition delays on the order of 1–30 ms in most of cases, which are comparable with the existing liquid hypergolic bipropellant systems. The minimum ignition delay time was recorded for boron case at 1.33 ms. And the calculated activation energy for the gelled ethanol fuel with pure and energetic particle substitution system resided within the range of 7–13 kJ/mole along with shear thinning behavior. Temperature profile also indicated an exothermic nature of the propellant system with 1000 to 1600 K recorded. Parameters such as apparent viscosity of the fuel, drop height and drop volume also played an important role for the hypergolicity of the system in a drop experimentation. It was also observed that the formation of a cage encapsulating the high temperature gases in a network formed by the gelling agent could result in a longer ignition delay.

The effects of various ambient pressure and temperature conditions on the ignition characteristics of kerosene-based nanofluid droplets were investigated experimentally. Individual kerosene droplet containing 0.1 or 1% by mass was mounted on the tip of silicon carbide (SiC) fiber and exposed to ambient temperatures in the range of 400–700 °C and ambient pressures in the range of 0.1–2.5 MPa under normal gravity. An increase in ambient pressure was observed to reduce the ignition location distance below a droplet. The ignition delay times of pure kerosene droplets were also examined for comparison. The results showed that the ignition delay time of Al NPs-laden kerosene droplets decreased exponentially with increasing temperature, as did that of pure kerosene droplets. An ambient pressure increase from 0.1 to 2.5 MPa led to a decrease in the lowest ambient temperature for ignition from 800 to 400 °C. At pressures greater than 1 MPa, the ignition delay times of droplets with 1% Al were shorter than those of pure kerosene and kerosene with 0.1% Al. Furthermore, as the ambient pressure increased from 0.1 to 2.5 MPa, the ignition delay was found to decrease and then increase exceeding the limiting pressure.

The blanket shield block (SB) shall be required the tight tolerance because SB interfaces with many components, such as flexible support keypads, First Wall (FW) support contact surfaces, FW central bolt, electrical strap contact surfaces and attachment inserts for both FW and Vacuum Vessel (VV). In order to fulfil the tight tolerance requirement, stress relieving shall be performed for dimensional stability after cover welding operation. In this paper, effect of Post Weld Heat Treatment (PWHT) conditions, temperature and holding time, was investigated on the residual stress and hardness. The 316L Stainless Steel (SS) was prepared and welded by manual TIG welding by using filler material with 2.4 mm of diameter. Welded 316L SS plate was machined to prepare the specimen for PWHT. PWHT was implemented at 250, 300, 400 °C for 2 and 3 h (400 °C only) and residual stress after relaxation were determined. The evaluation of residual stress and hardness for each specimen was carried out by instrumented indentation technique. The residual stress and hardness were decreased with increasing the heat treatment temperature and holding time.

The microstructural and electrochemical properties of anodes obtained by impregnation of the La0.4Sr0.6Ti0.8Mn0.2O3±d (LSTM) oxide system into two types of anode substrates such as Ni/ 8YSZ substrate (Ni (E)/ 8YSZ) and partially Ni removed Ni/ 8YSZ substrate (Ni(R)/8YSZ) were investigated in order to apply them as anode material for solid oxide fuel cells. All of the samples with LSTM impregnated on Ni (R)/ 8YSZ show higher electrical conductivity values than those of unimpregnated Ni (E)/ 8YSZ under dry H2 condition. The highest electrical conductivity values of 2041.2, 1877.4, and 1764.3 S/cm at 700, 800 and 900 °C can be achieved by samples with 3 wt% impregnated LSTM on Ni (R)/ 8YSZ. From the XPS analysis, the existence of a Ti metal peak on the surface of LSTM was only measured for the LSTM (3 wt%)-Ni (R)/ 8YSZ sample, metallic titanium on the surface can improve the electrical catalytic reaction. LSTM (3 wt%)-Ni (R)/ 8YSZ showed higher electrical conductivity values then those of LSTM (3 wt%)-Ni (E)/ 8YSZ in all the temperature ranges measured in the case of dry CH4 supply. Finally, the electrical conductivity of LSTM (3 wt%)-Ni (R)/ 8YSZ was stably maintained even when exposed to dry CH4 condition at 900 °C for a long time (100 h). © 2020 Elsevier B.V.

Interconnect integrated solid oxide fuel cells (II-SOFC) have remaining design and process issues due to their differences in thermal and mechanical properties between metal and non-metal materials. In this work, a lightweight design of an II-SOFC using metal foam and a high temperature sinter-joining process, which is one of the less expensive fabrication methods, is proposed for mobile and automotive applications, and the electrochemical performance is evaluated. 8 mol% of Y 2 O 3 stabilized ZrO 2 (8YSZ) is used as electrolyte and NiO/8YSZ as anode material. Ce 0.9 Gd 0.1 O 1.9 (CGO91) and Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−d (BSCF)/Sm 0.2 Ce 0.8 O 1.9 (SDC) are used as the in-situ buffer layer and in-situ composite cathode, respectively; to avoid oxidation of the metal interconnect, no additional sintering process is employed. A very strong bonding property is achieved at the ceramic-metal interface; the cell has a maximum power density of 0.37 W cm −2 at 800 °C in hydrogen operating conditions.

To quantify the potential contamination induced by exhaust plume from the MBB 10 N bipropellant thruster firing, we performed plume impingement analyses on the sensitive surfaces. The heat and mass fluxes of chemical species on the spacecraft surfaces and on the specific area of sensor units (optical port and radiator) were evaluated. A fully unstructured three-dimensional Direct simulation Monte Carlo (DSMC) code was developed and validated with measurements. A geostationary satellite with an optical port and radiator was selected and the actual configuration of the satellite was simplified by considering a bipropellant thruster, which is a major plume source to the sensitive surfaces, two communication antennas, and satellite panels. The DSMC computations show that the mass distribution or plume gas composition is unevenly distributed due to the mass separation effect, which occurs from the rapid expansion into vacuum especially around the nozzle lip at the backflow region. H2O is known as the most critical contaminant species; however, its plume impingement effect on the sensitive surfaces is negligible compared to the evaporation rate calculated by Langmuir’s evaporation equation. Not only have the results contributed to the geostationary satellite development, but also these findings are expected to be significant in designing spacecraft configurations and useful in the trade-off studies.

The autoignition and combustion characteristics of a single water/n-decane emulsion droplet were examined using a rapid compression machine. A specific volume ratio of water was added to the n-decane, and a water-in-oil emulsion was formed by ultrasonication. The emulsion droplet was suspended at the tip of a fine thermocouple and placed at the center of the reaction chamber. The time evolutions of droplet temperature and diameter were observed. Droplet combustion was classified into four stages, and the characteristics of each stage varied little with the water volume ratio. Ignition delay increased monotonically with initial droplet diameter and water volume ratio. Increasing the water ratio boosted the intensity of micro explosions, while the rise in droplet temperature was hindered by the specific heat and latent heat of the water. The average burning rate was elevated when the initial droplet diameter increased. However, the burning rate was not affected much by the water volume ratio.