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Microstructural evolution and strengthening mechanisms of Mg-3Sn-1Ca based alloys with additions of different amounts of AlN nano-particles were investigated. It was found that with increasing the amount of AlN nano-particles the grain size decreases obviously. The existence of AlN nano-particles could refine the primary crystal phases CaMgSn, which provided more heterogeneous nucleation sites for the formation of magnesium. Moreover, such nano-particles could also restrict the grain growth during solidification. After adding AlN nano-particles, both the tensile properties at room temperature and high temperature 250 °C and the hardness are largely improved. The improvement of strength is attributed to grain refinement and second phase refinement.

Long-haired individuals in the Tianzhu white yak population are a unique genetic resource, and have important landscape value. Copy number variation (CNV) is an important source of phenotypic variation in mammals. In this study, we used resequencing technology to detect the whole genome of 10 long-haired Tianzhu white yaks (LTWY) and 10 normal-haired Tianzhu white yaks (NTWY), and analyzed the differences of CNV in the genome of LTWYs and NTWYs. A total of 110268 CNVs were identified, 2006 CNVRs were defined, and the distribution map of these CNVRs on chromosomes was constructed. The comparison of LTWYs and NTWYs identified 80 differential CNVR-harbored genes, which were enriched in lipid metabolism, cell migration and other functions. Notably, some differential genes were identified as associated with hair growth and hair-follicle development (e.g., ASTN2, ATM, COL22A1, GK5, SLIT3, PM20D1, and SGCZ). In general, we present the first genome-wide analysis of CNV in LTWYs and NTWYs. Our results can provide new insights into the phenotypic variation of different hair lengths in Tianzhu white yaks.

Tianzhu white yak is a rare local yak breed with a pure white coat in China. In recent years, breeders have discovered long-haired individuals characterized by long hair on the forehead in the Tianzhu white yak, and the length and density of the hair on these two parts of the body are higher than that of the normal Tianzhu white yak. To elucidate the genetic mechanism of hair length in Tianzhu white yak, we re-sequence the whole genome of long-haired Tianzhu White yak (LTWY) (n = 10) and normal Tianzhu White yak (NTWY) (n = 10). Then, fixation index (FST), θπ ratio, cross-population composite likelihood ratio (XP-CLR), integrated haplotype score (iHS), cross-population extended haplotype homozygosity (XP-EHH), and one composite method, the de-correlated composite of multiple signals (DCMS) were performed to discover the loci and genes related to long-haired traits. Based on five single methods, we found two hotspots of 0.2 and 1.1 MB in length on chromosome 6, annotating two (FGF5, CFAP299) and four genes (ATP8A1, SLC30A9, SHISA3, TMEM33), respectively. Function enrichment analysis of genes in two hotspots revealed Ras signaling pathway, MAPK signaling pathway, PI3K-Akt signaling pathway, and Rap1 signaling pathway were involved in the process of hair length differences. Besides, the DCMS method further found that four genes (ACOXL, PDPK1, MAGEL2, CDH1) were associated with hair follicle development. Henceforth, our work provides novel genetic insights into the mechanisms of hair growth in the LTWY.

The considerable increase of the heat flux and chips density on the phased array antenna has brought great challenges to the thermal management. The objective of the work is to explore an effective scheme to achieve ideal uniform temperature distribution and lower maximum temperature with the condition of non-uniform heat flux. Taking into account of the high efficiency of microchannel heat sink and the promising performance of the two-phase flow boiling heat transfer due to its merit in keeping uniform surface temperature, a novel two-phase spider netted microchannel network heat sink is proposed in this paper. Firstly, a three-dimensional fluid-solid-thermal conjugate model is developed to investigate the flow boiling heat transfer performance of the spider-netted microchannel network numerically. During the numerical calculation, a multi-scale meshing generation method is proposed to reduce modeling difficulties on the premise of proper mesh quality. Then, the flow boiling heat transfer experiment is conducted to verify the reasonable of the model and the simulation results. Finally, the flow boiling heat transfer performance in the spider netted microchannel network is compared to the typical straight microchannel network. Results show that the proposed structure yields better flow boiling heat transfer performance with lower thermal resistance and more satisfactory temperature uniformity mainly due to its uniform flow distribution and enhanced vapor movement. It is also found that the temperature uniformity has reached 1.58 °C at heat flux of 100 W/cm2, but it decreases with the increase of heat flux. This situation cannot be effectively solved by means of increasing inlet flow rate. Thus the structure optimization is conducted to enhance the flow boiling heat transfer performance further, and the optimal structure can meet requirements of temperature uniformity within 2 °C at higher heat flux of 150 W/cm2.

A layered perovskite oxide Y0.8Ca0.2BaCoFeO5+d (YCBCF) was synthesized as a novel cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs) by citric acid-nitrates self-propagating combustion method. The phase and microstructure of YCBCF were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The average thermal expansion coefficient (TEC) of YCBCF was 14.6×10−6 K−1, which was close to other materials of SOFC at the range of RT-1000 °C. An open-circuit potential of 0.75 V and a maximum output power density of 426 mW/cm2 were obtained at 650 °C in a Sm0.2Ce0.8O1.9 (SDC)-based anode-supported SOFC by using humidified (∼3% H2O) hydrogen as fuel and static air as oxidant. The results indicated that the YCBCF was a promising cathode candidate for IT-SOFCs.

Computational Fluid Dynamics (CFD) is employed in this paper to study the cavitation flow near a damping groove of a valve plate inside an axial piston pump. Effects of common U-shaped groove and V-shaped groove on the cavitation phenomenon are analyzed, and the process of cavitation bubbles from growth to collapse is studied numerically. It is shown that the cavitation can be effectively restrained to a certain extent by increasing the number of V-shaped grooves or the aspect ratio of the cross section of a U-shaped groove under the same flow area. The erosion caused by the cavitation can be effectively reduced leading to a substantial improvement of the reliability and lifespan of axial piston pumps.

Solid oxide electrolyzers have attracted a great deal of interest in recent years because they can convert electrical energy into chemical energy with high efficiency. Ni/YSZ cathodes are generally utilized for high temperature electrolysis of H 2 O and CO 2 in oxygen-ion conducting solid oxide electrolyzers; however, such electrodes can only operate under reducing conditions. In an atmosphere without a flow of reducing gas, cathodes based on La 0.2 Sr 0.8 TiO 3+ δ (LST) are a promising alternative. Solid Oxide Electrolyzers with LST cathodes without pre-reduction were used at 700 °C for the electrolysis of 3%H 2 O/97%N 2 and 100%CO 2 , and promising polarization impedance data were obtained in both atmospheres. The electrochemical results indicated that the electrochemical reduction of the La 0.2 Sr 0.8 TiO 3+ δ cathode was the main process at low electrical voltages, while the electrolysis was the main process at high voltages because ion transportation in the electrolyte limited the overall efficiency. The electrolysis of H 2 O was determined to be more efficient than the electrolysis of CO 2 under the same conditions. The Faraday efficiencies of H 2 O and CO 2 were 85.0% and 24.7%, respectively, at 700 °C and a 2 V applied potential.

Nano-sized CSO (Ce 0.80 Sm 0.20 O 2− δ ) and CSCO (Ce 0.79 Sm 0.20 Cu 0.01 O 2− δ ) were synthesized by the PVA assisted combustion method, and then characterized by the structure of PVA–cation complexes and nano-powders, as well as mechanical and electrical performance after sintering. The results indicate that the PVA–cation complexes (PVA–(Ce 3+ ,Sm 3+ ) and PVA–(Ce 3+ ,Sm 3+ ,Cu 2+ )) were formed by coordinating metal cations to hydroxyl groups, as well as the COO −1 group derived from the oxidation of PVA with NO 3 −1 . Low temperatures (around 200 °C) caused intense combustion reactions, resulting in the direct crystallization of cubic fluorite nano-CSO (10–20 nm) and nano-CSCO (10–15 nm) crystals with homogeneous element distribution. This slight compositional modification of CSO by co-doping with 1 mol% CuO resulted in a significantly lowered densification temperature, as well as enhanced mechanical and electrical property. The strength improvement can be ascribed to the dense and fine-grained microstructure without normal grain coarsening, resulting in a transgranular-dominant fracture mode during strength testing.

Combustion processed nano-sized Ce0.79Sm0.20Co0.01O2−δ (CSCoO) and Ce0.80Sm0.20O2−δ (CSO) were sintered at various temperatures, and mechanical properties and microstructures were characterized. The results demonstrate that besides a lowering of sintering temperature to achieve sufficient densification, the doping of very minor amounts of CoO (1 mol%) to CSO significantly enhanced mechanical properties. The CSCoO sintered at 1100 °C exhibits a biaxial flexural strength of 354 ± 42 MPa which compared with 194 ± 57 MPa for CSO with a similar relative density sintered at 1400 °C. This slight modification in chemical composition also resulted in a slight improvement in micro-hardness.

BaZr0.1Ce0.7Y0.2O3−δ (BZCY) electrolyte has been extensively studied as novel electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs). In this short communication, we report our progress on the fabrication and characterization of the high performance anode supported BZCY cell. Maximum power density of 650 mW/cm2 at 700 °C is obtained for the single cell with configuration of Ni-BZCY/BZCY (20 um)/SSC-BZCY. Further, significant performance enhancement is observed during long-term stability test at 600 °C under constant voltage of 0.5 V, indicating excellent stability of BZCY under fuel cell operating condition. Those results indicate that BZCY based cell is very promising for practical applications.

Porous cordierite ceramics were prepared using sepiolite source of MgO and SiO2 and alumina as starting materials by simple dry-pressing/sintering. The sepiolite/alumina green bodies were sintered at 1100–1350 °C for 2 h. The characterization was focused on thermal analysis, phase evolution, sintering behavior, thermal expansion and micro-structural changes using DSC/TG, XRD, dilatometry and SEM. α-Cordierite was formed above 1200 °C, the amount of which increased steadily with the sintering temperature. Increasing sintering temperature also improved the densification (especially above1000 °C), and decreased the thermal expansion (especially above 1200 °C). Porous cordierite with a bimodal pore size distribution (1.4–1.9 μm and 10 μm) was prepared with cornstarch as pore-former.

Mullite ceramics were fabricated at relatively low sintering temperatures (1500–1550 °C) from recycled flyash and bauxite with MgO addition as raw materials. The densification behavior was investigated as function of magnesia content and sintering temperature. The results of thermal analysis, bulk density and pore structure indicate that MgO addition effectively promoted sintering, especially above 1450 °C. Due to the presence of large interlocked elongated mullite crystals above 1450 °C, associated with enhanced densification, an improvement in mechanical strength was obtained for the samples containing magnesia. The addition of magnesia slightly decreases the LTEC at 1300 °C due to the formation of low-expansion α-cordierite, but slightly increases the LTEC above 1400 °C due to the formation of high expansion corundum and MgAl2O4 spinel.

Nano-sized Ce 0.8 Gd 0.2 O 2−δ and Ce 0.79 Gd 0.2 Cu 0.01 O 2−δ electrolyte powders were synthesized by the polyvinyl alcohol assisted combustion method, and then characterized by powder characteristics, sintering behaviors and electrical properties. The results demonstrate that the as-synthesized Ce 0.8 Gd 0.2 O 2−δ and Ce 0.79 Gd 0.2 Cu 0.01 O 2−δ possessed similar powder characteristics, including cubic fluorite crystalline structure, porous foamy morphology and agglomerated secondary particles composed of gas cavities and primary nano crystals. Nevertheless, after ball-milling these two powders exhibited quite different sintering abilities. A significant reduction of about 400 °C in densification temperature of Ce 0.79 Gd 0.2 Cu 0.01 O 2−δ was obtained when compared with Ce 0.8 Gd 0.2 O 2−δ. The Ce 0.79 Gd 0.2 Cu 0.01 O 2−δ pellets sintered at 1000 °C and the Ce 0.8 Gd 0.2 O 2−δ sintered at 1400 °C exhibited relative densities of 96.33% and 95.7%, respectively. The sintering of Ce 0.79 Gd 0.2 Cu 0.01 O 2−δ was dominated by the liquid phase process, followed by the evaporation-condensation process, Moreover, Ce 0.79 Gd 0.2 Cu 0.01 O 2−δ shows much higher conductivity of 0.026 S cm −1 than Ce 0.8 Gd 0.2 O 2−δ (0.0065 S cm −1 ) at a testing temperature of 600 °C.

Tubular porous alumina ceramic membrane supports were fabricated by an extrusion–drying–sintering process and then characterized in detail in terms of corrosion resistance in both H2SO4 and NaOH aqueous solutions. Variations in the properties of the alumina supports such as mass loss percent, mechanical strength, open porosity and pore size distribution were studied before and after corrosion under different conditions. In addition, the microstructures were analyzed using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction before and after corrosion. The fabricated porous alumina supports offer possibilities for some potential applications as micro-filtration or ultra-filtration membrane supports, as well as in the pre-treatment of strongly acidic industrial waste-liquids.

(Pr 0.5 Nd 0.5 ) 0.7 Ca 0.3 CrO 3− δ (PNCC) interconnect materials are stable in SOFC operating conditions. To improve the sintering ability and electrical conductivity of PNCC, a composite of PNCC/SDC interconnect materials was synthesized by a sol–gel auto-ignition process. The XRD results indicate that PNCC is chemically stable against reaction with SDC at high temperatures. Additionally, SDC-doped PNCC has enhanced sintering activity and electrical conductivity compared to PNCC alone. For 5 wt.% SDC, the relative density of the sample was 95.8% after sintering at 1400 °C, and the electrical conductivity of the sample reached 59.6 S cm −1 in air and 4.48 S cm −1 in H 2 at 650 °C. Both of these values are higher than those of pure PNCC. The average thermal expansion coefficient of the samples is close to that of other components of SOFCs. Our results indicate that PNCC/SDC composites are promising intermediate materials for IT-SOFCs.

Synthetic hydrocarbon fuels from CO2/H2O are proposed as alternatives to hydrogen as an energy carrier to enable a carbon neutral energy cycle, given their inherent advantages of high H/C ratio and convenience of storage and transportation. Here we demonstrate the successful electrochemical reduction of CO2 into CO and CH4 in a proton conducting solid oxide electrolyser based on BaCe0.5Zr0.3Y0.16Zn0.04O3 − δ (BCZYZ) electrolyte and a composite iron/iron oxide cathode. The production of CH4 and CO reaches 0.07 and 3.25 ml min−1 cm−2, respectively, with 1.5 A cm−2 at 614 °C. The overall CO2 conversion rate in the electrochemical reduction process is 65%.

To reduce the membrane fouling of oil–water emulsion, the commercial Al2O3 microfiltration membrane (MF) was modified with nano-sized Al2O3 grains by in-situ hydrolysis method. The nano coating formed by the Al2O3 grains and the modified MF were characterized. The results show that the nano-sized Al2O3 grains were only deposited on the surfaces of the Al2O3 grain in the MF. The coating does not act as a filter layer, just changes the character of the membrane surface which becomes more hydrophilic. The coating decreases the mean pore sizes of the modified MF by 12.5%, but increases the pure water flux by about 27% due to the existence of the boundary slip. The hydrophilic coating prevents the modified MF from being fouled using stable emulsion as feed. The water flux of the modified MF increases 20% than the unmodified one. The effects of cross-flow velocity on the flux and the oil rejection are also discussed.

Membrane fouling weakens seriously the membrane's separating performance, which can be reduced by the membrane surface modification. Commercial Al2O3 microfiltration membranes were modified by the nano-sized ZrO2 coating to reduce the membrane fouling by oil droplets and to keep the unique character of the inorganic membrane. The nano-sized ZrO2 coating is prepared by in situ hydrolysis of ZrCl4. The results show that the nano-coating does not form a separating layer, and just makes the ceramic membrane more hydrophilic. Using the stable 1 g/L 20# engine oil–water emulsion as feed, the steady flux of the modified membrane is obtained in a very short time. The steady flux keeps 88% of the initial flux and the oil rejection is above 97.8%. The hydrophilic nano-sized coating, the backflushing and the appropriate cross-flow velocity contribute to reducing the membrane fouling by oil droplets. The modified membrane has the good performance in the oil–water separation of stable emulsions.

Both tubular and button solid oxide fuel cells (SOFCs) with configuration NiO–YSZ/YSZ/PNSM–YSZ were assembled and compared in their performance. A refined particle suspension coating technique was used for preparing thin dense YSZ electrolyte layer on the two types of anode supports, and the thickness of YSZ membrane was controlled by the time of tubular anode dipped into YSZ suspension and the suspension volume dropped onto the button anode, respectively. Current–voltage tests and AC impedance measurements were carried out to characterize the performance and ohmic resistances in the two cells. Compared with tubular cell, higher peak power density values of 933 mW cm −2 at 850 °C was achieved, which is 2.2 times higher than the value of tubular cell. AC impedance indicated that lower performance of tubular cell was restricted by the ohmic loss at the operating temperatures.

This paper presents Pervoskite-type BaCo0.7Ta0.1Fe0.2O3−δ (BCTF) cathode for intermediate temperature proton conducting solid oxide fuel cells (SOFCs). BCTF with cubic phase shows excellent structural stability and adequate chemical stability against CO2/H2O in contrast to BaCo0.8Fe0.2O3−δ. Conductivity of BCTF reaches above 10 S cm−1 in air at intermediate temperatures. Composite cathode polarization resistance (BCTF/BaZr0.1Ce0.7Y0.2O3−δ) in a symmetric cell based on proton conducting BaZr0.1Ce0.7Y0.2O3−δ (BCZY) electrolyte was as low as 0.1 Ω cm2 at 700 °C. The maximum output of anode-supported thin-film SOFC with BCTF/BCZY composite cathode and BCZY electrolyte reaches 255 mW cm−2 when employing humidified H2 as fuel and static air as oxidizer.

A NiO–YSZ anode-supported hollow fiber solid oxide fuel cell (HF-SOFC) has been fabricated with redox stable (La0.75Sr0.25)0.95Cr0.5Mn0.5O3−δ–Sm0.2Ce0.8O1.9–YSZ (LSCM–SDC–YSZ) composite cathode. The characterization of NiO–YSZ hollow fibers prepared by the phase inversion method is focused on the microstructure, porosity, bending strength and electrical conductivity. A thin YSZ electrolyte membrane (about 10 μm) can be prepared by a vacuum-assisted dip-coating process and is characterized in terms of microstructure and gas-tightness. The performance of the as-prepared HF-SOFC is investigated at 750–850 °C with humidified H2 as fuel and ambient air as the oxidant. The peak power densities of 513, 408 and 278 mW cm−2 can be obtained at 850, 800 and 750 °C, respectively, and the corresponding interfacial polarization resistances are 0.14, 0.29 and 0.59 Ω cm2. The high performance at intermediate-to-high temperatures could be attributed to thin electrolyte and proper composite cathode with low interfacial polarization resistance. The low interfacial polarization resistance suggests potential applications of LSCM–SDC–YSZ composite oxides as the redox stable cathode. This investigation indicates that the redox stable LSCM–SDC–YSZ is a promising cathode material system for the next generation YSZ-based HF-SOFC. The results will be expected to open up a new phase of the research on the micro-tubular SOFCs.

A cobalt-free cubic perovskite oxide Sm0.5Sr0.5Fe0.8Cu0.2O3−δ (SSFCu) was investigated as a novel cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). The thermal expansion coefficient (TEC) of SSFCu was close to that of Sm0.2Ce0.8O1.9(SDC) electrolyte and the electrical conductivity of SSFCu sample reached 72–82 S cm−1 in the commonly operated temperatures of IT-SOFCs (400–600 °C). Symmetrical electrochemical cell with the configuration of SSFCu/SDC/SSFCu was applied for the impedance study and area specific resistance (ASR) of SSFCu cathode material was as low as 0.085 Ω cm2 at 700 °C. Laboratory-sized tri-layer cells of NiO-SDC/SDC/SSFCu were operated from 450 to 700 °C with humidified hydrogen (∼3% H2O) as fuel and the static air as oxidant. A maximum power density of 808 mW cm2 was obtained at 700 °C for the single cell.

Zirconia single crystal nano-particles containing pores were prepared by a sol–gel-hydrothermal method. The unique character of the particles is that some irregular pores are embedded within the single crystals. The results of XRD, TEM and FT-IR show that the gaseous hydrolysates of the superstoichiometric urotropine are the origin of the pores. The gel structure and the hydrothermal treatment are the required conditions resulting in the pores in crystals. The formation mechanism was proposed: zirconia gel was formed after the reaction of ZrOCl 2 with urotropine. The superstoichiometric urotropine was dissolved and distributed uniformly in the gel. The small pores were generated because gaseous hydrolysates of urotropine were constrained in the gel during the hydrothermal treatment. During the process of the amorphous gel transferred into the crystals, some of the pores coarsened with the crystals growth. Big pores disappeared due to the break of the crystals. And only the small pores were remained in the interior of crystals, which could hardly be eliminated by the subsequent crystal growth if the calcination temperature is below 550 °C. Thus, the zirconia nano-particles containing pores were generated.

Reversible solid oxide fuel cells (R-SOFCs) are regarded as a promising solution to the discontinuity in electric energy, since they can generate electric powder as solid oxide fuel cells (SOFCs) at the time of electricity shortage, and store the electrical power as solid oxide electrolysis cells (SOECs) at the time of electricity over-plus. In this work, R-SOFCs with thin proton conducting electrolyte films of BaCe 0.5 Zr 0.3 Y 0.2 O 3−δ were fabricated and their electro-performance was characterized with various reacting atmospheres. At 700 °C, the charging current (in SOFC mode) is 251 mA cm −2 at 0.7 V, and the electrolysis current densities (in SOEC mode) reaches −830 mA cm −2 at 1.5 V with 50% H 2 O–air and H 2 as reacting gases, respectively. Their electrode performance was investigated by impedance spectra in discharging mode (SOFC mode), electrolysis mode (SOEC mode) and open circuit mode (OCV mode). The results show that impedance spectra have different shapes in all the three modes, implying different rate-limiting steps. In SOFC mode, the high frequency resistance ( R H ) is 0.07 Ωcm 2 and low frequency resistances ( R L ) are 0.37 Ωcm 2 . While in SOEC mode, R H is 0.15 Ωcm 2 , twice of that in SOFC mode, and R L is only 0.07 Ωcm 2 , about 19% of that in SOFC mode. Moreover, the spectra under OCV conditions seems like a combination of those in SOEC mode and SOFC mode, since that R H in OCV mode is about 0.13 Ωcm 2 , close to R H in SOEC mode, while R L in OCV mode is 0.39 Ωcm 2 , close to R L in SOFC mode. The elementary steps for SOEC with proton conducting electrolyte were proposed to account for this phenomenon.

A NiO–YSZ anode-supported hollow fiber solid oxide fuel cell (HF-SOFC) has been fabricated with stable (Pr 0.5 Nd 0.5 ) 0.7 Sr 0.3 MnO 3− δ –YSZ (PNSM–YSZ) composite cathode. The NiO–YSZ hollow fiber anode was prepared by the immersion-induced phase inversion technique and shows a special asymmetrical structure with long and large finger-like porous structure near the lumen side of the hollow fiber. A thin and dense YSZ electrolyte membrane (about 10 μm) was deposited on the anode by a vacuum-assisted dip-coating process. The performance of the as-prepared HF-SOFC was tested at 600–800 °C with humidified H 2 as fuel and ambient air as the oxidant. The peak power densities of 459, 325 and 172 mW cm −2 can be obtained at 800, 700 and 600 °C, respectively. The good performance at intermediate temperatures indicates promising applications as power sources for portable devices for the prepared YSZ-based micro-tubular SOFCs with PNSM–YSZ composite cathode.

Highly permeable porous yttria-stabilized zirconia (YSZ) hollow fiber membranes have been developed by a combined phase inversion and sintering technique. Ethanol substituting for usual water was used as the external coagulant in order to prepare YSZ hollow fiber membranes with low trans-membrane resistance. The prepared YSZ hollow fiber membranes show a special asymmetric structure with an outer skin layer, highly porous inner surface and sub-layer composed of long and large finger-like pores. The influences of sintering temperature on the microstructure, porosity and pore size distribution, bending strength and pure water flux were investigated in detail. Results show that YSZ hollow fiber membranes with high permeability and enough bending strength can be prepared using ethanol as the external coagulant and by controlling the sintering temperature. The outer-skinned YSZ hollow fiber membranes show a pure water flux of 2.27–4.30 m 3 m −2 h −1 bar −1 and a bending strength of 154.5–201.7 MPa when sintered between 1350 and 1400 °C. The prepared YSZ hollow fiber membranes are suitable to be used for microfiltration and as support for other composite membranes.

A cobalt-free perovskite oxide Ba0.5Sr0.5Fe0.8Cu0.2O3−δ (BSFC) is employed as a cathode material for intermediate-temperature proton-conducting solid oxide fuel cells. Symmetrical electrochemical cell with the configuration of BSFC-BZCY/BZCY/BSFC-BZCY is applied for the impedance study. The single cell, consisting of BSFC-BZCY/BZCY/NiO-BZCY structure, is assembled and tested from 600 to 700 °C with humidified hydrogen (∼3% H2O) as the fuel and the static air as the oxidant. A maximum power density of 430 mW cm−2 is obtained at 700 °C for the single cell. Long-term stability of the BSFC-BZCY/BZCY/NiO-BZCY single cell at 600 °C for 40 h has also been studied. Preliminary results demonstrat that cobalt-free oxide BSFC is a very promising cathode for application in proton-conducting solid oxide fuel cells.

The perovskite La 0.6 Sr 0.4 Co 0.8 Cu 0.2 O 3− δ (LSCCu) oxide is synthesized by a modified Pechini method and examined as a novel cathode material for low-temperature solid oxide fuel cells (LT-SOFCs) based upon functional graded anode. The perovskite LSCCu exhibits excellent ionic and electronic conductivities in the intermediate-to-low-temperature range (400–800 °C). Thin Sm 0.2 Ce 0.8 O 1.9 (SDC) electrolyte and NiO–SDC anode functional layer are prepared over macroporous anode substrates composed of NiO–SDC by a one-step dry-pressing/co-firing process. A single cell with 20 μm thick SDC electrolyte on a porous anode support and LSCCu–SDC cathode shows peak power densities of only 583.2 mW cm −2 at 650 °C and 309.4 mW cm −2 for 550 °C. While a cell with 20 μm thick SDC electrolyte and an anode functional layer on the macroporous anode substrate shows peak power densities of 867.3 and 490.3 mW cm −2 at 650 and 550 °C, respectively. The dramatic improvement of cell performance is attributed to the much improved anode microstructure that is confirmed by both SEM observation and impedance spectroscopy. The results indicate that LSCCu is a very promising cathode material for LT-SOFCs and the one-step dry-pressing/co-firing process is a suitable technique to fabricate high performance SOFCs.

A dense BaCe 0.8 Sm 0.2 O 5+ δ (BCS) electrolyte was fabricated on a porous anode by in situ drop-coating to develop a simple and cost-effective route to fabricate proton-conducting solid oxide fuel cells (SOFCs). Layered perovskite-structure oxides SmBaCuCoO 5+ δ (SBCC) and SmBaCuFeO 5+ δ (SBCF) were prepared and the electrical conductivity, the thermal expansion coefficient and electrochemical performance were investigated as potential cathode materials for proton-conducting SOFCs. Thermal expansion coefficients of SBCC and SBCF were suitable for BCS electrolyte and the electrical conductivity of the SBCC is higher than that of the SBCF. The maximum power density of 449 mW cm 2 and 333 mW cm 2 at 700 °C were obtained for the SBCC/BCS/NiO–BCS and SBCF/BCS/NiO–BCS cells, respectively. The interfacial polarization resistances for SBCC and SBCF cathode are as low as 0.137 Ω cm −2 and 0.196 Ω cm −2 at 700 °C, respectively. The results indicate that the SBCC and SBCF are promising cathode materials for proton-conducting SOFCs.

Layered perovskite LaBaCuFeO5+x (LBCF) and LaBaCuCoO5+x (LBCC) oxides are synthesized by a modified Pechini method and examined as potential cathode materials for intermediate-temperature protonic ceramic membrane fuel cells (IT-PCMFCs). Thin proton-conducting BaZr0.1Ce0.7Y0.2O3−δ (BZCY) electrolyte and NiO–BaZr0.1Ce0.7Y0.2O3−δ (NiO–BZCY) anode functional layer are prepared over porous anode substrates composed of NiO–BaZr0.1Ce0.7Y0.2O3−δ by a one-step dry-pressing/co-firing process. Laboratory-sized quad-layer cells of NiO-BYCZ/NiO-BYCZ/BYCZ/LBCF (LBCC) are operated from 550 to 700 °C with humidified hydrogen (∼3% H2O) as fuel and the static air as oxidant. The single cell with LBCF cathode shows peak power densities of only 327 mW cm−2 at 700 °C and 105 mW cm−2 for 550 °C, while the single cell with LBCC cathode shows peak power densities of 432 and 171 mW cm−2 at 700 and 550 °C, respectively. The dramatic improvement of cell performance is attributed to higher cobaltites catalytic activity than that of ferrites for IT-PCMFCs, which is in good agreement with the results of impedance measurement.

The interconnect materials La0.7Ca0.3Cr1−xZnxO3−δ (x=0, 0.01, 0.03, 0.05, 0.07) were prepared by a microwave assisted sol-gel auto-ignition process. The crystalline structures of the samples were characterized by X-ray diffraction (XRD) and the lattice parameters were evaluated with Rietveld method. For Ca-Zn co-doped LaCrO3 with x=0.03, the sintering activity was improved, and the relative density came up to 96.5% for the sample sintered at 1300 °C for 10 h. The electrical conductivity of the samples was increased from 21.1 S/cm to the maximum of 70.9 S/cm at 650 °C in air, with the x content increasing from 0.01 to 0.03. However, with x further increasing, the electrical conductivity was decreased. The average thermal expansion coefficient (TEC) of the samples at RT–1000 °C in air was ca. 10.0 × 10−6 K−1. All data indicated that the La0.7Ca0.3Cr1−xZnxO3−δ series ceramics would be potential candidate to be used as an interconnect materials for IT-SOFCs.

A new concept of solid oxide fuel cells (SOFCs), the simple SOFCs, that is simply composed of an electronic conductor and an ionic conductor is investigated, which evidently simplifies the assembly and further maintenance of the cell system. High-performance interconnect material chromium deficient lanthanum calcium chromites La0.7Ca0.3Cr0.97O3−δ (LCC97) perovskite oxides are prepared by a modified Pechini method and examined as both anode and cathode materials for SOFCs based on the state-of-the-art YSZ electrolyte. Chemical compatibility, sintering character, electrical conductivity and thermal expansion are investigated to characterize the compatibilities of LCC97 with YSZ. The XRD analysis indicates LCC97 chemically compatible with YSZ. The LCC97 sintered at 1250 °C have the conductivity of 62.0 S cm−1 at 850 °C in air, which is about 2.6 times as high as that of La0.7Ca0.3CrO3−δ with no chromium deficiency. At 850 °C, the ASRs is only 0.15 Ω cm2 for LCC97–YSZ composite cathode. LCC97-based simple SOFCs (LCC97–YSZ/YSZ/LCC97–YSZ) offer promising performance using H2 as fuel and thick YSZ electrolytes. An open-circuit potential of 1.06 V, a maximum power density of 92.1 mW cm−2, and a polarization resistance of the electrodes of 2.17 Ω cm2 are achieved at 850 °C.

BaZr 0.1 Ce 0.7 Y 0.2 O 3− δ (BZCY7) exhibits adequate proton conductivity as well as sufficient chemical and thermal stability over a wide range of SOFC operating conditions, while layered SmBa 0.5 Sr 0.5 Co 2 O 5+ δ (SBSC) perovskite demonstrates advanced electrochemical properties based on doped ceria electrolyte. This research fully takes advantage of these advanced properties and develops novel protonic ceramic membrane fuel cells (PCMFCs) of Ni-BZCY7|BZCY7|SBSC. The results show that the open-circuit potential of 1.015 V and maximum power density of 533 mW cm −2 are achieved at 700 °C. With temperature increase, the total cell resistance decreases, among which electrolyte resistance becomes increasingly dominant over polarization resistance. The results also indicate that SBSC perovskite cathode is a good candidate for intermediate temperature PCMFC development, while the developed Ni-BZCY7|BZCY7|SBSC cell is a promising functional material system for next generation SOFCs.

The layered perovskite structure oxide NdBaCo2O5+δ (NBCO) with rapid oxygen ion diffusion and surface exchange kinetics was synthesized by auto ignition process and initially examined as a cathode for proton-conducting fuel cells (H-SOFCs). The single cell, consisting of NdBaCo2O5+δ (NBCO)/BaZr0.1Ce0.7Y0.2O3−δ (BZCY)/NiO–BaZr0.1Ce0.7Y0.2O3−δ (BZCY) structure, was assembled and tested from 650 to 700 °C with humidified hydrogen (∼3% H2O) as the fuel and air as the oxidant. A maximum power density of 438 mW cm−2 at 700 °C was obtained for the single cell and electrochemical performance of the cell was studied.

A novel layered perovskite oxide PrBaCuCoO5+i (PBCCO) is employed as a potential cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Thermal expansion and electrochemical performance on samarium-doped ceria (SDC) electrolyte are evaluated. The thermal expansion coef- ficient (TEC) of PrBaCuCoO5+i (PBCCO) is close to that of SDC electrolyte and electrical conductivity of PrBaCuCoO5+i (PBCCO) reaches the general required value of cathode material. Symmetrical electro- chemical cell with the configuration of PrBaCuCoO5+i (PBCCO)/SDC/PrBaCuCoO5+i (PBCCO) applied for the impedance studies, the area specific resistance of PrBaCuCoO5+i (PBCCO) cathode is as low as 0.047 � cm2 at 700

Bulk porous mullite supports for ceramic membranes were prepared directly using a mixture of industrial waste fly ash and bauxite by dry-pressing, followed by sintering between 1200 and 1550 degrees C. The effects of sintering temperature on the phase composition and shrinkage percent of porous mullite were studied. The XRD results indicate that secondary mullitization reaction took place above 1200 degrees C, and completed at 1450 degrees C. During sintering, the mixture samples first shrunk, then expanded abnormally between 1326 and 1477 degrees C, and finally shrunk again above 1477 degrees C. This unique volume self-expansion is ascribed to the secondary mullitization reaction between bauxite and fly ash. More especially, the micro-structural variations induced by this self-expansion sintering were verified by SEM, porosity, pore size distribution and nitrogen gas permeation flux. During self-expansion sintering, with increasing temperature, an abnormal increase in both open porosity and pore size is observed, which also results in the increase of nitrogen gas flux. The mineral-based mullite supports with increased open porosity were obtained. Furthermore, the sintered porous mullite membrane supports were characterized in terms of thermal expansion co-efficient and mechanical strength.

Titanium alloys are used widely for their high strength-to-weight ratio and good corrosion resistance characteristics. However, these alloys have been classified as ‘difficult-to-machine’ materials. In order to improve the cutting efficiency in machining the titanium alloys, a new WC matrix composite tool material was prepared by hot pressing technology in this research. The cutting performance of the newly developed tool material in machining titanium alloy Ti6Al4V was investigated. The factors which influence the wear modes of the tool were investigated and the wear mechanisms were analyzed. Results show that the high temperature and mechanical friction are the main factors in the wear process. The wear mechanisms of the tool in machining titanium alloys are adhesion wear and abrasive wear.