Electrical behavior of the Ruddlesden–Popper phase, (Nd0.9La0.1)2 Ni0.75Cu0.25O4 (NLNC) and NLNC- x wt% Sm0.2Ce0.8O1.9 (SDC) (x = 10, 30 and 50), as intermediate‐temperature solid oxide fuel cells cathode

In the present work, a new Ruddlesden-Popper phase, (Nd_0.9La_0.1)₂ Ni_0.75Cu_0.25O₄ (NLNC) has been synthesized by solid state reaction for intermediate-temperature solid oxide fuel cells (IT-SOFCs) applications. The effect of sintering temperature on the microstructure and electrical properties of the NLNC cathode material is investigated. Likewise, composite cathode materials were also prepared by mixing the NLNC with 10, 30 and 50 wt% of Sm_0.2Ce_0.8O_1.9 (SDC) powders, and firing in the temperature range of 1000–1300 °C. The crystal structure and chemical compatibility of NLNC and SDC, and their microstructures were studied by XRD and SEM, respectively. Electrical conductivity and performance of monolithic and composite electrodes as a function of the electrode composition is investigated experimentally through four probe method and electrochemical impedance spectroscopy (EIS). The results proved that no reaction occur between NLNC and SDC compounds even at a temperature as high as 1300 °C. Maximum total electrical conductivity of 114.36 S cm^?1 at 500 °C is recorded for the pure NLNC material sintered at 1300 °C. The polarization resistance of pure NLNC cathode was 0.43 Ω cm² at 800 °C; the NLNC–SDC composite cathodes including 10, 30 and 50 wt% SDC displayed Rp value of 0.27 Ω cm², 0.11 Ω cm², and 0.19 Ω cm² at 800 °C, respectively.     

Co2O3 substitution effects on the structure and microwave dielectric properties of low-firing (Zn0.9Mg0.1)TiO3 ceramics

Low-firing (Zn_0.9Mg_0.1)_1?xCo_xTiO₃ (x = 0.02–0.10) (ZMC_xT) microwave dielectric ceramics with high temperature stability were synthesized via conventional solid-state reaction. The influences of Co₂O₃ substitution on the phase composition, microstructure and microwave dielectric properties of ZMC_xT ceramics were discussed. Rietveld refinement results show the coexistence of ZnTiO₃ and ZnB₂O₄ phases at x = 0.02–0.10. (Zn_0.9Mg_0.1)_1?xCo_xTiO₃ ceramic with x = 0.06 (ZMC_0.06T) obtains the best combination microwave dielectric properties of: ε_r = 21.58, Q × f = 53,948 GHz, τ_f = ? 54.38 ppm/°C. For expanding its application in LTCC field, 3 wt% ZnO-B₂O₃-SiO₂ (ZBS) and 9 wt% TiO₂ was added into ZMC_0.06T ceramic, great microwave dielectric properties were achieved at 900 °C for 4 h: ε_r = 26.03, Q × f = 34,830 GHz, τ_f = ? 4 ppm/°C, making the composite ceramic a promising candidate for LTCC industry.     

Characteristics of Ba(Zr0.1Ce0.7Y0.2)O3-δ nano-powders synthesized by different wet-chemical methods for solid oxide fuel cells

Ba(Zr_0.1Ce_0.7Y_0.2)O_3-δ nano-particles were prepared by different wet-chemical synthesis, Pechini (BZCY(P)) and co-precipitation (BZCY(C)), respectively. The BZCY(C) powders have a particle size in range of about 50–150 nm, which is smaller than the BZCY(P) powders with about 500–900 nm. Both the BZCY materials show perovskite structures, but there are impurities in the BZCY (P). Moreover, the electrolyte density was higher in the BZCY (C) than the BZCY (P). The single cells with BZCY (C) electrolytes exhibited about 0.23 W cm^?2 at 600 °C and about 0.31 W cm^?2 at the same temperature were obtained when the anode-functional layer was introduced between the anode and electrolyte. Thus, the BZCY prepared by carbonate-derived co-precipitation method can be more favorable for high-purity and dense electrolytes in the solid oxide fuel cells than the BZCY prepared by Pechini method.     

Highly efficient La0.8Sr0.2MnO3-δ - Ce0.9Gd0.1O1.95 nanocomposite cathodes for solid oxide fuel cells

La_0.8Sr_0.2MnO_3-δ-Ce_0.9Gd_0.1O_1.95 (LSM-CGO) nanostructured cathodes are successfully prepared in a single process by a chemical spray-pyrolysis deposition method. The cathode is composed of nanometric particles of approximately 15 nm of diameter, providing high triple-phase boundary sites for the oxygen reduction reactions. A low polarization resistance of 0.046 Ω cm² is obtained at 700 °C, which is comparable to the most efficient cobaltite-based perovskite cathodes. A NiO-YSZ anode supported fuel cell with the nanostructured cathode generates a power output of 1.4 W cm^?2 at 800 °C, significantly higher than 0.75 W cm^?2 for a cell with conventional LSM-CGO cathode. The results suggest that this is a promising strategy to achieve high efficiency electrodes for Solid Oxide Fuel Cells in a single preparation step, simplifying notably the fabrication process compared to traditional methods.     

Liquid-phase synthesis of SrCo0.9Nb0.1O3-δ cathode material for proton-conducting solid oxide fuel cells

A novel liquid-phase synthesis strategy is demonstrated for the preparation of the Nb-containing ceramic oxide SrCo_0.9Nb_0.1O_3-δ (SCN). In comparison with the traditional solid-state reaction (SSR) method, the liquid-phase synthesis route offers a couple of advantages, including a lower phase formation temperature and a smaller particle size of the SCN materials that are beneficial for applications as proton-conducting fuel cell cathode. With BaCe_0.4Zr_0.4Y_0.2O_3-δ (BCZY442) as the electrolyte and the SCN synthesized in this work as the cathode, a proton-conducting solid oxide fuel cell (SOFC) shows a peak power density of 348 mW cm^?2 at 700 °C, significantly higher than that of a SOFC fabricated with SCN cathode prepared using the SSR method, which can only deliver 204 mW cm^?2 at the same temperature. Additionally, this new synthesis strategy allows impregnation of Sr²⁺, Co³⁺and Nb⁵⁺ on the solid backbone in aqueous solution, further improving cell performance to reach a peak power density of 488 mW cm^?2 at 700 °C.     

On the mechanical,thermophysical and dielectric properties of Nextel™ 440 fiber reinforced nitride matrix (N440/Nitride) composites

The Nextel? 440 fiber reinforced nitride matrix (N440/Nitride) composites were fabricated by precursor infiltration and pyrolysis (PIP) route. The results demonstrated that the original N440 fiber had a phase composition of amorphous SiO₂ and γ-Al₂O₃. Its single filament tensile strength was 3.03 GPa (at room temperature), while it dropped to 72.6% and 35.1% at 1200 °C and 1400 °C, respectively. The phase content of N440/Ntride composites was mainly γ-Al₂O₃ and amorphous BN, as well as mullite phase (formed at > 1100 °C). The composites owned a flexural strength up to 76.0 MPa at room temperature. The stair-stepping decrease in the load-displacement curve and fiber pull-outs in the fracture surface indicated a good fiber/matrix interface and toughness. By heating at 1400 °C, the composites still possessed 67.4% of original bending strength. It was found that the high temperatures caused strong fiber-matrix bonding and severe fiber degradation. The specific heat, CTE and thermal conductivity of the composites were 0.325–0.586 J g^?1 K^?1, (3.2–4.0) × 10^?6 K^?1 and 0.78–3.47 W m^?1 K^?1, respectively. The composites possessed a dielectric constant of 4.25–4.35 and loss tangent of 0.004–0.01 at 8–12 GHz. The good overall performances enabled the N440/Nitride composites advanced high-temperature wave-transparent applications.     

Performance and stability in H2S of SrFe0.75Mo0.25O3-δ as electrode in proton ceramic fuel cells

The H₂S-tolerance of SrFe_0.75Mo_0.25O_3-δ (SFM) electrodes has been investigated in symmetric proton ceramic fuel cells (PCFC) with BaZr_0.8Ce_0.1Y_0.1O_3-δ (BZCY81) electrolyte. The ionic conductivity of the electrolyte under wet reducing conditions was found to be insignificantly affected in the presence of up to 5000 ppm H₂S. The fuel cell exhibited an OCV of about 0.9 V at 700 °C, which dropped to about 0.6 V and 0.4 V upon exposure to 500 and 5000 ppm H₂S, respectively, on the fuel side. Post characterization of the fuel cell revealed significant degradation of the anode in terms of microstructure and chemical composition due to formation of sulfides such as SrS, MoS₂ and Fe₃S₄. Nevertheless, the fuel cell was still functional due to the sufficient electronic conductivity of some of these sulfides.     

Electrochemical and thermal characterization of doped ceria electrolyte with lanthanum and zirconium

Nanocomposites electrolytes consisting of La³⁺ and Zr⁴⁺ doped with ceria labelled as La_0.2 Ce_0.8 O_2-δ (LDC), Zr_0.2Ce_0.8O_2-δ (ZDC) and Zr_0.2La_0.2Ce_0.6O_2-δ (ZLDC) have been synthesized via a co-precipitation route. DC conductivity was studied with a four-probe method in the range of temperature 450–650 °C and maximum conductivity was found to be 0.81 × 10^?2 S.cm^?1 (LDC) > 0.32 × 10^?2 S.cm^?1 (ZLDC) > 0.15 × 10^?2 S.cm^?1 (ZDC) at a temperature of 650 °C, respectively. Further, electric behavior of doped and co-doped ceria electrolytes was investigated by A.C electrochemical impedance spectroscopy (frequency range ~ 0.1 Hz?4 MHz). The phase/structural identification of the material prepared was studied using X-ray diffraction and found ceria to possess a cubic fluorite structure. Scanning electron microscopy (SEM) was carried out to study its morphology and particle size (~ 90–120 nm). Thermal behavior on its change in weight and length with the temperature were studied by thermogravimetric analysis (TGA) and dilatometry respectively. Furthermore, thermal expansion coefficients (TECs) of prepared electrolytes are calculated and found as follows: 13.4 × 10^?6 °C^?1, 13.6 × 10^?6 °C^?1and 15.3 × 10^?6 °C^?1 for LDC, ZDC and ZLDC, respectively, in the temperature range 150–1150 °C.     

Facile modified synthesis and intermediate temperature electrical properties of Sn0.95Al0.05P2O7/KSn2(PO4)3 composite electrolyte

In this study, Sn_0.95Al_0.05P₂O₇ and a novel dense Sn_0.95Al_0.05P₂O₇/KSn₂(PO₄)₃ composite electrolytes were synthesized. The structural characterization of X–ray diffraction (XRD) and microstructual properties of scanning electron microscopy (SEM) were carried out. The XRD results indicated that an in-situ reaction between Sn_0.95Al_0.05P₂O₇ and inorganic melt salt take place to form the Sn_0.95Al_0.05P₂O₇/KSn₂(PO₄)₃ composite. The intermediate temperature electrical properties were determined by using impedance spectroscopy, oxygen concentration cell and hydrogen concentration discharge cell. Finally, the H₂/O₂ fuel cell using the Sn_0.95Al_0.05P₂O₇/KSn₂(PO₄)₃ as electrolyte membrane was constructed and the obtained maximum power output densities were 67.7 mW cm^?2 and 142.1 mW cm^?2 at 650 °C and 700 °C, respectively.     

Influence of small amounts of gallium oxide addition on ionic conductivity of La0.9Sr0.1Ga0.8Mg0.2O3-δ solid electrolyte

The effects of small amounts of gallium oxide on intragrain and intergrain conductivity of La_0.9Sr_0.1Ga_0.8Mg_0.2O_3-δ are investigated by impedance spectroscopy in the 280–420 °C range. Bulk specimens with 0.5, 1.0 and 1.5 mol% gallium oxide are prepared by solid state reaction at 1350 °C. All specimens achieved relative density values higher than 95%. The additive promotes grain growth indicating solid solution formation. A small fraction of the additive remains at grain boundaries and increases the fraction of the gallium-rich, LaSrGa₃O₇, impurity phase. The intragrain conductivity of gallium oxide containing specimens is higher than that of the parent solid electrolyte. Similar effect is found for the intergrain conductivity, which is maximum for 1 mol% gallium oxide addition.     

Study of structure and conductivity of Li3/8Sr7/16-3x/2LaxZr1/4Nb3/4O3 solid electrolytes

Li_3/8Sr_7/16-3x/2La_xZr_1/4Nb_3/4O₃ (x = 0, 0.05, 0.10, 0.15, 0.20) were synthesized using the conventional solid-state reaction method. In order to increase the vacancy concentration, La³⁺ was doped on the Sr²⁺ site. Crystal structures of doped samples were characterized by X-ray diffraction. Except, perovskite-type Li_3/8Sr_7/16-3x/2La_xZr_1/4Nb_3/4O₃ (x = 0, 0.05, 0.10, 0.15) samples were fabricated by heat treatment at 1250 °C, 1275 °C, 1275 °C and 1275 °C, respectively, for 15 h. Lattice sizes decreased with the increase of doping amounts because of the smaller ion radius of La³⁺ compared to that of Sr²⁺. Ionic conductivities of the samples were measured by AC impedance spectroscopy. The results showed that the ionic conductivity increases at first and then decreases with raising doping amounts and sintering temperatures. So the optimized composition Li_3/8Sr_7/16-3x/2La_xZr_1/4Nb_3/4O₃ (x = 0.05) sintered at 1275 °C was selected with the highest total conductivity of 3.33 × 10^?5 S cm^?1at 30 °C and an activation energy of 0.27 eV. Additionally, potentiostatic polarization test was used to evaluate the electronic conductivity. The optimal composition Li_3/8Sr_7/16-3x/2La_xZr_1/4Nb_3/4O₃ (x = 0.05) as a possible Li-ion conducting solid electrolyte has an electronic conductivity of only 8.39 × 10^?9 S cm^?1.     

Studies on spinel cobaltites,MCo2O4 (M = Mn,Zn, Fe,Ni and Co) and their functional properties

Optimization of electrodes for charge storage with appropriate processing conditions places significant challenges in the developments for high performance charge storage devices. In this article, metal cobaltite spinels of formula MCo₂O₄ (where M = Mn, Zn, Fe, Ni and Co) are synthesized by oxalate decomposition method followed by calcination at three typical temperatures, viz. 350, 550, and 750 °C and examined their performance variation when used as anodes in lithium ion batteries. Phase and structure of the materials are studied by powder x-ray diffraction (XRD) technique. Single phase MnCo2O4,ZnCo2O4 and Co3O4 are obtained for all different temperatures 350 °C, 550 °C and 750 °C; whereas FeCo₂O₄ and NiCo₂O₄ contained their constituent binary phases even after repeated calcination. Morphologies of the materials are studied via scanning electron microscopy (SEM): needle-shaped particles of MnCo₂O₄ and ZnCo₂O₄, submicron sized particles of FeCo₂O₄ and agglomerated submicron particle of NiCo₂O₄ are observed. Galvanostatic cycling has been conducted in the voltage range 0.005–3.0 V vs. Li at a current density of 60 mA g^?1 up to 50 cycles to study their Li storage capabilities. Highest observed charge capacities are: MnCo₂O₄ – 365 mA h g^?1 (750 °C); ZnCo₂O₄ – 516 mA h g^?1 (550 °C); FeCo₂O₄ – 480 mA h g^?1 (550 °C); NiCo₂O₄ – 384 mA h g^?1 (750 °C); and Co₃O₄ – 675 mA h g^?1 (350 °C). The Co₃O₄ showed the highest reversible capacity of 675 mA h g^?1; the NiO present in NiCo₂O₄ acts as a buffer layer that results in improved cycling stability; the ZnCo₂O₄ with long needle-like shows good cycling stability.     

Structure,densification and electrical properties of Gd3+ and Cu2+ co-doped ceria solid electrolytes for SOFC applications: Effects of Gd2O3 content

Ceria-based solid electrolytes exhibit superior electrical conductivity compared to traditional yttria-stabilized zirconia ceramics. However, they require high sintering temperatures to achieve full densification. Transition metal oxides exhibiting low melting points, such as CuO, have been used as additives to lower the sintering temperature of these materials. In this context, the present work is focused on the evaluation of the effects of gadolinium oxide (Gd₂O₃) content on the structure, densification and electrical properties of ceria co-doped with CuO. Nominal compositions of Ce_0.99?xGd_xCu_0.01O_2-δ (0 ≤ x ≤ 0.3) were synthesized by the polymeric precursor method. The precursor powders were characterized by simultaneous thermogravimetry and differential thermal analysis (TG/DTA) and the calcined powders were studied by X-ray diffraction (XRD) and Rietveld refinement to obtain crystallographic parameters. The sinterability of green bodies was evaluated by dilatometry up to 1200 °C. The relative density was determined in samples sintered between 950 and 1050 °C and the microstructural characterization was performed by scanning electron microscopy (SEM). The electrical properties were investigated by impedance spectroscopy (IS). The XRD results confirms the formation of a cubic fluorite type structure in the entire composition range. The lattice parameters obtained by Rietveld refinement showed a reduction in the crystallite size with increasing gadolinium content. Densification was improved with increasing Gd-content up to x = 0.15. The electrical conductivity was enhanced by gadolinium addition, reaching a maximum of 7.81 mS cm^?1 at 600 °C for the composition x = 0.15 sintered at a temperature as low as 1050 °C.     

Carbon-coated Li2S cathode for improving the electrochemical properties of an all-solid-state lithium-sulfur battery using Li2S-P2S5 solid electrolyte

Li₂S is coated with carbon to improve the electrical conductivity of the composite cathode in all-solid-state lithium-sulfur batteries. Carbon is applied by thermal evaporation from a polyacrylonitrile (PAN) source at 600 °C for 5 h. It is shown that the carbon coating is impurity free, and the crystallinity of Li₂S is well maintained. The electronic conductivity of Li₂S is dramatically improved from 9.21 × 10^?9 S cm^?1 to 2.39 × 10^?2 S cm^?1 upon carbon coating. An all-solid-state battery prepared with the carbon-coated Li₂S shows a high initial capacity of 585 mAh g^?1 (g of Li₂S) that increases up to 730 mAh g^?1 (g of carbon-coated Li₂S) by the 10th cycle. This high capacity is stable throughout the 25 cycles tested, with an excellent coulombic efficiency of 99%. Carbon-coated Li₂S is advantageous for all-solid-state batteries due to the increased electrical conductivity, while allowing a reduction of the total carbon content present in the composite cathode.     

Fabrication and performance of dielectric tape based on CaO-B2O3-SiO2 glass/Al2O3 for LTCC applications

A non-aqueous tape-casting process for fabricating CaO-B₂O₃-SiO₂ glass/Al₂O₃ dielectric tape for LTCC applications was investigated. An isopropanol/ethanol/xylene ternary solvent-based slurry was developed by using castor oil, poly(vinyl butyral), and dibutyl phthalate as dispersant, binder, and plasticizer, respectively. The effects of dispersant concentration, binder content, plasticizer/binder ratio, and solid loading, on the properties of the casting slurry and resultant tape were systematically investigated. The results showed that the optimal values for the dispersant and binder contents, plasticizer/binder ratio, and solid loading were 2.0 wt%, 7.5 wt%, 0.6, and 62 wt%, respectively. The resultant flexible and uniform, 120-μm-thick CaO-B₂O₃-SiO₂ glass/Al₂O₃ tape had a density of 1.90 g/cm^?3, tensile strength of 1.66 MPa, and average surface roughness of 310 nm. Laminated tapes sintered at 875 °C for 15 min exhibited excellent properties: relative density of 97.3%, ε_r of 7.98, tan δ of 1.3 × 10^?3 (10 MHz), flexural strength of 205 MPa, and thermal expansion coefficient of 5.47 ppm/°C. The material demonstrated good chemical compatibility with Ag electrodes, indicating a significant potential in LTCC applications.     

Microstructure and mechanical properties of ZTA composites fabricated by oscillatory pressure sintering

The influence of sintering temperature on the microstructure and mechanical properties of Al₂O₃?20 wt% ZrO₂ composites fabricated by oscillatory pressure sintering (OPS) was investigated by means of X-ray diffraction, scanning electron microscopy, three-point bending test and Vickers indentation. Results were compared to specimens obtained by conventional hot pressing (HP) under a similar sintering schedule. The optimum oscillatory pressure sintering temperature was found to be 1600 °C; almost fully dense materials (99.94% of theoretical density) with homogeneous microstructure could be achieved. The highest flexural strength, fracture toughness and hardness of such composites reached 1145 MPa, 5.74 MPa m^1/2 and 19.08 GPa when sintered at 1600 °C, respectively. Furthermore, the oscillatory pressure sintering temperature could be decreased by more than 50 °C as compared with the HP method, OPS favouring enhanced grain boundary sliding, plastic deformation and diffusion in the sintering process.     

Low-temperature sintering of Ti1−xCux/3Nb2x/3O2 (x = 0.23) microwave dielectric ceramics with CuO and B2O3 addition

The influence of CuO and B₂O₃ addition on the sintering behavior, microstructure and microwave dielectric properties of Ti_1?xCu_x/3Nb_2x/3O₂ (TCN, x = 0.23) ceramic have been investigated. It was found that the addition of CuO and B₂O₃ successfully reduced the sintering temperature of TCN ceramics from 950 to 875 °C. X-ray diffraction studies showed that addition of CuO-B₂O₃ has no effect on the phase composition. The TCN ceramics with 0.5 wt% CuO-B₂O₃ addition showed a high dielectric constant of 95.63, τ_f value of + 329 ppm/°C and a good Q × f value of 8700 GHz after sintered at 875 °C for 5 h, cofirable with silver electrode.     

Experiments and transient finite element simulation of γ-Y2Si2O7/B2O3-Al2O3-SiO2 glass coating on porous Si3N4 substrate under thermal shock

A dense γ-Y₂Si₂O₇/B₂O₃-Al₂O₃-SiO₂ glass coating was fabricated by slurry spraying method on porous Si₃N₄ ceramic for water resistance. Thermal shock failure was recognized as one of the key failure modes for porous Si₃N₄ radome materials. In this paper, thermal shock resistance of the coated porous Si₃N₄ ceramics were investigated through rapid quenching thermal shock experiments and transient finite element analysis. Thermal shock resistance of the coating was tested at 700 °C, 800 °C, 900 °C and 1000 °C. Results showed that the cracks initiated within the coating after thermal shock from 800 °C to room temperature, thus leading to the reduction of the water resistance. Based on the finite element simulation results, thermal shock failure tended to occur in the coating layer with increasing temperature gradient, and the critical thermal shock failure temperature was measured as 872.24 °C. The results obtained from finite element analysis agree well with that from the thermal shock tests, indicating accuracy and feasibility of this numerical simulation method. Effects of thermo-physical properties for the coating material on its thermal shock resistance were also discussed. Thermal expansion coefficient of the coating material played a more decisive role in decreasing the tangent tensile stress.     

Sintering behaviour,microstructural characterisation and thermal expansion properties of Sn substituted ZrMo2O8

The coefficient of thermal expansion (CTE) of ZrMo₂O₈ can be fine-tuned by controlling the amount of tin substitution in zirconium lattice sites. The sintering challenges associated with this material and the optimal sintering conditions were investigated in this study. Powders of tin substituted ZrMo₂O₈ were synthesised by co-precipitation technique. X-ray diffraction studies confirmed the formation of cubic SnMo₂O₈. Sintered pellets were produced from the powders and optimal sintering without decomposition of the phase was achieved at the expense of porosity. The material was found to be thermally stable up to 600 °C using thermogravimetric analysis. Dilatometric analysis of the sintered compacts shows that the CTE of the sample is in the order of 3.9 × 10^?6/K, between 25 °C and 600 °C.     

Enhancing copper infiltration into alumina using spark plasma sintering to achieve high performance Al2O3/Cu composites

Al₂O₃/Cu (with 30 wt% of Cu) composites were prepared using a combined liquid infiltration and spark plasma sintering (SPS) method using pre-processed composite powders. Crystalline structures, morphology and physical/mechanical properties of the sintered composites were studied and compared with those obtained from similar composites prepared using a standard liquid infiltration process without any external pressure. Results showed that densities of the Al₂O₃/Cu composites prepared without applying pressure were quite low. Whereas the composites sintered using the SPS (with a high pressure during sintering in 10 min) showed dense structures, and Cu phases were homogenously infiltrated and dispersed with a network from inside the Al₂O₃ skeleton structures. Fracture toughness of Al₂O₃/Cu composites prepared without using external pressure (with a sintering time of 1.5 h) was 4.2 MPa m^1/2, whereas that using the SPS process was 6.5 MPa m^1/2. These toughness readings were increased by 18% and 82%, respectively, compared with that of pure alumina. Hardness, density and electrical resistivity of the samples prepared without pressure were 693 HV, 82.5% and 0.01 Ω m, whereas those using the SPS process were 842 HV, 99.1%, 0.002 Ω m, respectively. The enhancement in these properties using the SPS process are mainly due to the efficient pressurized infiltration of Cu phases into the network of Al₂O₃ skeleton structures, and also due to high intensity discharge plasma which produces fully densified composites in a short time.