Isothermal Dwell Research Articles

Ultralow‐Temperature Sintering of Titanium Powder by Spark Plasma Sintering Under Cyclic Pressure

Spark plasma sintering (SPS) is a promising method for producing titanium components from powder but a limitation is that high sintering temperatures (>900 °C) are normally required to eliminate porosity. Herein, the SPS of commercially pure titanium powder is reported using both cyclic and constant uniaxial pressure and compare densification, microstructure, and mechanical behavior. The following parameters are varied: sintering temperature, TS, 400 to 900 °C; cyclic and constant pressures, 100 to 500 MPa; with and without an isothermal dwell of 60 min at TS. The mechanical behavior is determined by bend and tensile testing. It is demonstrated that the application of cyclic pressure (cyclic‐SPS) gives superior densification over the range of parameters investigated compared with a constant pressure. Bend testing reveals improved ductility after cyclic‐SPS compared with a constant pressure. The dwell at TS further improves mechanical properties, giving excellent tensile ductility and strength. Consequently, at the ultralow temperature of 500 °C, nearly fully dense, ductile, titanium is achieved. It is shown that cyclic pressure enhances the degree of powder compaction at room temperature, and mechanisms are proposed to rationalize the effect of cyclic‐SPS on enhancing the rates of densification and sintering as the temperature increases during processing.

Enhancing carbon fibre recovery through optimised thermal recycling: Kinetic analysis and operational parameter investigation

Thermal recycling is an attractive method for recovering carbon fibre from carbon fibre-reinforced polymer (CFRP) composite waste. The main drawbacks of the thermal recycling approach are its high operational cost resulting from significant energy requirements and the risk of fibre surface damage caused by overheating. In this research, we will establish an optimal heating temperature and operating parameters (such as atmosphere, heating rates and isothermal dwelling time) through an analysis of the kinetic behaviour of CFRP thermal degradation to obtain clean and undamaged recycled fibres, while minimising energy requirements. The results show that a higher conversion fraction can be reached by applying a lower nitrogen flow rate, moderate heating rate and cap temperature of 425 °C. To ensure the complete removal of any residual matrix and pyrolytic carbon, and to obtain clean recycled carbon fibres, an additional recycling step is employed. In this case, oxidation is conducted with a 45-min isothermal period following pyrolysis. Using the proposed method, it was possible to retain 87.6 % of the fibre's tensile modulus and 80.3 % of its strength after the recycling process. The outcomes of this research will contribute to production of high-grade recycled carbon fibres with controlled mechanical performance and physical characteristics.

Evaluation of Strengthening Mechanisms in Novel Fully Ferritic Advanced High‐Strength Steels

New steel alloying concepts are designed in order to produce a fully ferritic, low‐alloy steel with high (1 GPa) ultimate tensile strength (TS). A simulated hot‐deformation process of the Ti–Mo–V–Nb and Ti–Mo–V steels is designed for that purpose, and the strengthening mechanisms of the steels are evaluated after the isothermal dwell at three different temperatures (590, 630, and 680 °C). The TS and the yield strength (YS) of the test alloys are estimated via hardness measurements. Results show that the estimated TS of over 1000 MPa and YS of over 900 MPa can be achieved in both steels, although the contribution of different strengthening mechanisms to the YS varies between the steels. The effect of the dislocation strengthening can especially compensate the reduced effect of the precipitation strengthening at all tested coiling temperatures (CTs). Based on the results, a CT range of 590–630 °C with the 1800 s dwell time seems to be a potential process window for the studied steels after the present thermomechanically controlled processing (TMCP) route.

Reappraising Crystallization Kinetics with Overgrowth Chronometry: an in Situ Study of Olivine Growth Velocities

Abstract We investigated the early stages of olivine crystal growth via in situ seeded experiments in a single plagioclase-hosted melt inclusion, using a heating stage microscope. Each experiment was subjected to a cooling ramp of 7800°C/h followed by an isothermal dwell at 19°C, 38°C, 57°C, 77°C, 96°C or 129°C of undercooling. The seeds (6–16 μm in diameter Ø) grew into large crystals (Ø 80–169 μm) in 3 to 30 min through the symmetrical development of tabular, skeletal, and dendritic overgrowths as the undercooling of the system increased. Time-resolved image processing and incremental measurements of the overgrowth thicknesses indicate up to three stages of crystal growth: an acceleration stage, a linear (constant growth rate) stage, and a deceleration stage. At the isotherm, the growth velocities reach a stable maximum that in all experiments corresponds to the period of linear growth. The highest linear values are measured at the $\left\{101\right\}$ interfaces, from 2.1 × 10−8 m/s at 19°C of undercooling to 4.8 × 10−7 m/s at 129°C of undercooling. Crystal growth is slower at other interfaces, in the ranges 1.9–7.6 × 10−8 m/s and 4.5 × 10−9 – 7.6 × 10−8 m/s for the $\left\{100\right\}$ and $\left\{001\right\}$ forms, respectively. Growth in the $<010>$ dimension appears limited to less than 2.4 × 10−8 m/s at 129°C of undercooling. We constrain the uncertainty on these growth velocities, which includes the environmental conditions (± 8.6°C on the nominal undercooling) and the measurements of crystal lengths (underestimated by <16% at most fast interfaces). A systematic and comprehensive review of 19 pre-existing datasets indicates that our linear growth velocities are faster than most growth rates determined at comparable undercoolings. Growth rates determined as half crystal lengths divided by total time are intrinsically low estimates of the true maximum, linear growth velocities, because the total time includes periods of slower or non-growth, and measured crystal dimensions are subject to projection foreshortening or truncation. These errors can lead to values that are several times to several orders of magnitude lower than the true maximum growth rates. This study completes and refines previously published data on the crystallization kinetics of olivine, highlighting the sensitivity of growth rates to specific environmental conditions and measurement methods. We emphasize the importance of symmetrical growth and true maximum growth velocities for interpreting olivine growth histories.

Unraveling the Correlation between the Synthesis Time and Electrochemical Performance of Transition Metal Layered Oxides by In Situ Neutron Powder Diffraction

Ni-rich layered transition metal oxides are promising cathodes for Li-ion batteries due to their low cost and high theoretical capacity. However, their practical applications are hindered by the capacity fading caused by intrinsic lattice structure variations, such as changes in the atom arrangement and valence. In situ neutron powder diffraction is a powerful technique for studying the structure of battery materials and is expected to provide more information than other techniques due to its nondestructive, high-resolution, and light-element probing capability. Herein, we employed neutron powder diffraction to probe the structural evolution during the synthesis of LiNi0.5Co0.2Mn0.3O2 in real time, including the transition metal–oxygen/lithium–oxygen (TM–O/Li–O) bond, phase formation, and lattice parameters as a function of temperature and isothermal dwelling time. The results revealed that the lattice structure of cathode materials is a function of temperature and isothermal dwelling time. Variations of the TM–O/Li–O bond and lattice parameters with the dwelling time at an annealing temperature of 850 °C indicated that the instability of the structure of the layered transition metal oxides may be a possible mechanism for the changes in the discharging capacity and cycle stability of the battery performance. Our findings provide insights into the correlation between the annealing time of NCM cathodes and the electrochemical performance and can be very helpful for synthesizing high-performance transition metal layered oxide materials.

Prediction model of optimised process parameters for recycling carbon fibre composites

• Optimised process parameters for thermal recycling of thermoset carbon fibre reinforced polymer is presented. • Minimisation of carbon fibre degradation and maximisation of matrix removal is investigated. • Modelled results are validated with experimental and analytical results. • Improved integrity of recovered carbon fibre for achieving closed-loop recycling is discussed. A mathematical prediction model for identifying the most suitable process parameters for thermal recycling of thermoset carbon fibre reinforced polymer (TS-CFRP) composites is presented here. The process parameters of heating rate, maximum temperature and isothermal dwell time at the maximum temperature for recovery of carbon fibres depend on factors like the size of furnace and composite sample, composition and constituents of composites. The model considers such factors to give the most suitable process parameters so that the recovered carbon fibre has minimum degradation yet with maximum matrix removal. Modelled results on heat transfer, material conversion, radiation view factor, and predicted process parameters were verified with the experimental results. The model can provide a good prediction of the furnace process parameters and final matrix mass loss distribution by layer with an error percentage of five per cent. Using this prediction model with the TS-CFRP thermal recycling processes can assure conserving the original fibre value for closed loop recycling of carbon fibre.

Morphological and chemical evolution of transient interfaces during zinc oxide cold sintering process

Although zinc oxide has a high melting point of 1975 °C, the recent development of the cold sintering process has shown that highly dense polycrystalline ceramics can be obtained at 150 °C or below. As such unusual densification does not yet have fully elucidated underlying mechanisms, this study aims to provide a comprehensive investigation of transient morphological and chemical interfaces during isothermal dwell. The chemical “transient” interface involves the formation of a zinc carboxylate complex by reacting the host zinc oxide powder and acetic acid solution, which is later consumed for the recrystallization on the lattice of an adjacent grain with a decomposition of the complex. Hence, the final outcome can be a residual-free zinc oxide phase. Regarding the morphological evolution, gas physisorption studies were conducted to quantify the area of solid–vapor interfaces and the Schlaffer model was used to analyze the activation energy for specific surface area reduction. Moreover, transmission electron micrographs revealed that the recrystallization occurs at the interface between crystalline grain and carbon-rich amorphous phase. After 30 minutes of isothermal dwell, the area of the amorphous phase was significantly decreased while grain size was increased, potentially indicating the recrystallization-induced grain growth and pore closure. The chemical transition at the zinc oxide surface was further investigated using ReaxFF molecular dynamics simulation, observing that acetate molecule acts as a bridging complex to connect zinc ions to the surface. Overall, understanding the evolution of the transient interface is a crucial subject to obtaining a residual-free cold-sintered sample with desired grain size and properties for application developments.

In-situ introduction of highly active TiO for enhancing hydrogen storage performance of LiBH4

• A valid strategy to in-situ introduce highly active additive to LiBH 4 is employed. • TiO is in-situ introduced into LiBH 4 and the LiBH 4 -0.06TiO system is obtained. • Enhanced kinetics and favorable cycling stability are achieved for the system. • Li 3 BO 3 and TiH 2 are generated and act as catalysts for LiBH 4 . • Dehydrogenation energy barrier is reduced and formation of Li 2 B 12 H 12 is inhibited. LiBH 4 is a promising candidate for solid state hydrogen storage, however, it still suffers from high hydrogen desorption temperature, harsh hydrogen absorption conditions, and poor reversibility, which hinder its practical development. In this paper, a novel synthetic strategy of heat treating a LiBH 4 and Ti(OEt) 4 mixture is employed to prepare LiBH 4 system with TiO in-situ introduced. With an optimized TiO content of 0.06 in molar fraction, the LiBH 4 -0.06TiO system shows onset and peak dehydrogenation temperatures of 240 °C and 340 °C, respectively, which are 140 °C and 90 °C lower than those of the pure LiBH 4 . The LiBH 4 -0.06TiO system can rapidly release 9 wt% H 2 after dwelling at 400 °C for 10 min. The hydrogenation of the dehydrogenation product initiates at 150 °C, and a capacity of 9 wt% is reached after isothermal dwelling at 500 °C under 50 bar of H 2 for 100 min. The capacity retention of the system can reach 74.4% after 10 cycles, indicating a favorable reversibility. With the introduction of TiO, the apparent dehydrogenation activation energy of the system is evidently reduced, and the formation of Li 2 B 12 H 12 , a highly thermal stable intermediate phase, is greatly suppressed. In addition, the aggregation is evidently alleviated. All of these contribute to the enhanced dehydrogenation kinetics and reversibility. TiO reacts with LiBH 4 , forming Li 3 BO 3 and TiH 2 after the initial dehydrogenation, which play significant catalytic effect to LiBH 4 .

Rate and temperature dependent compaction-creep-recovery and void analysis of compression molded prepregs

This study investigates the compaction-creep response of a glass/epoxy prepreg system at different temperatures, pressures, and compaction speeds, using a compaction fixture with heated platens, housed in-situ in an X-ray computed tomography (XCT) machine. It has been shown that by increasing the compaction speed from 0.1 mm/min to 1 mm/min, the total strain, the percentage of compaction creep and the resulting permanent deformation increased for all of the temperature and pressure conditions considered in this study. It was noted that for all compaction speeds and pressures, the percentage of compaction-creep increases from 25 °C up to 55 °C and then decreases with further increases in temperature. A decrease in creep deformation with post creep-thickness recovery, due to the resin squeezing out from the prepreg, was observed at higher temperatures. The void content in the post-creep, fully cured laminates was determined using an analytical model, the results of which were compared with XCT-developed geometrical models. Good agreement between both approaches was observed, with differences in void content results of less than 12% being recorded. The optimum process parameters (55 °C, 0.3 MPa and 0.5 mm/min) were identified in compression molded prepreg samples to choose the first isothermal dwell period . The combination of these process parameters resulted in moderate levels of compaction-creep and permanent deformation as well as a low void volume fraction in the test samples. • Rate dependent thermo-mechanical compaction-creep tests were performed on uncured glass/epoxy prepreg samples. • Percentage of compaction-creep and permanent deformation are found to be increasing with the increase of compaction speed. • Void volume fraction was determined in cured samples using analytical and XCT-aided geometrical models and compared. • Normal distribution statistical analysis was employed to study the size and shape of individual voids.

Wettability and reactivity between molten aluminum and randomly aligned carbon nanotubes

The wettability and reactivity between molten aluminum (Al) and carbon nanotubes (CNTs) are a key issue in the preparation of CNTs-reinforced Al-matrix composites using a solidification route. In this work, we measured the wettability of randomly aligned multi-walled carbon nanotubes (buckypaper) by molten Al at 973–1173 K in a high vacuum using a modified sessile-drop method and examined their interactions using a droplet-sucking technique. The wettability between Al and CNTs is even worse than that of the Al/graphite system. The contact angles are basically larger than 140° and show only a sluggish decrease with time during isothermal dwelling. The chemical stability of CNTs in contact with Al is closely related to their structural integrity. The CNTs with good crystallinity and structural integrity have relatively high chemical stability and exhibit only a weak interfacial reaction with Al at 973 K. However, the stability of structural defective parts is much lower. They are readily eroded by molten Al, leading to the fragmentation of the CNTs. These CNT fragments having an open tubular structure are then rapidly dissolved in molten Al along the axial and radial directions. Simultaneously, a large amount of Al4C3 is formed at the interfaces.

Viscous flow spark plasma sintering of glass microspheres with YAG composition and high tendency to crystallization

Present work is focused on the preparation of bulk glass with stoichiometric yttrium aluminium garnet (YAG) composition, which has high tendency to crystallize. Glass microspheres were prepared by flame synthesis from sol-gel prepared YAG precursor. Sintering conditions in SPS apparatus such as heating rate, pressure and temperature were optimized with the aim to prepare transparent material. Results revealed that glass with high tendency to crystallize is very sensitive to time of densification under load (associated with the maximum applied temperature). The increase of the pressure led to the expansion of the translucent part of the sample. Dense, and slightly translucent amorphous samples (total transmission measured at 550 nm was 4.8 %) were successfully prepared by viscous flow SPS sintering of glass microspheres at temperatures below 910 °C without any isothermal dwell.

Subduction-collisional processes between the Eurasian and Philippine Sea plates: Constraints from thermal-age paths of the Taiwan Orogen

Records of the thermal-age path of orogenic rocks are crucial in understanding subduction and collisional processes between a continent and an arc. Tectonic events and thermochronological data of the Taiwan Orogen have been extensively investigated. We use the zircon UPb youngest ages as the (initial) subduction age, the Raman Spectroscopy of Carbonaceous Material, 40Ar/39Ar age of mica porphyroblasts, whole-rock LuHf isochron age and thermal results as prograde peak metamorphic condition during subduction and basal accretion, and the apatite fission-track data for cooling age of the Taiwan Orogen to illuminate the subduction and collisional processes between the Eurasian Plate and the Luzon Arc. The Hsuehshan Range Nappe in the west of the Taiwan Orogen, whose subduction was initiated at 12 Ma, reached peak metamorphism with a temperature of ~250 °C to 490 °C at a depth of 8 km during the interval 6–2.5 Ma, mainly by basal superimposed accretion. The isothermal dwelling during peak metamorphism condition of the Hsuehshan Range suggests that tectonic underplating through basal superimposed accretion contribute significantly to the formation of the Taiwan Orogen, and led to a sudden increase of subduction and décollement depths, and slow downward thickening of the orogenic wedge and mountain root growth. Located in the east of the Taiwan Orogen, the Yuli Beltsubduction was initiated at 15.4–16 Ma, and attained peak metamorphism at a depth of 40 km, with a temperature of 550–560 °C and a pressure of 10.5–13 kbar during the interval 12.2–4.4 Ma due to basal superimposed accretion. The exhumation of the Hsuehshan Range commenced at ~2.5 Ma, which is later than that of the Yuli Belt at ~3.4 Ma. Such distinct and different thermal-age paths of the Hsuehshan Range and the Tananao Complex indicate that different tectonic wedges in the Taiwan Orogen are formed through different subduction and accretional processes.

Effect of processing parameters on microstructure in brazing of Al–Si alloys

Phase transformations during melting, isothermal dwell and solidification of composite Al-Si+flux braze material are studied experimentally. A multistep mechanism of melting conjugated with Si diffusion, mushy zone formation and chemical reaction between flux and aluminum oxide is discussed. The impact of different processing parameters on final microstructure is described and quantified.

Preparation and crystal structure of ζ-Cr2(C,N) powders

In this work, the influence parameters, including synthesis temperature, nitrogen pressure, and isothermal dwell time, were systematically investigated during carbothermal preparation of ζ-Cr2(C,N) solid solution powders by using thermogravimetry differential scanning calorimetry, X-ray diffraction, scanning electron microscope, and composition analysis. The results showed that Cr2O3 began to be carbonized at ~ 1000 °C firstly and then was nitrided with the formation of Cr2(C,N) at elevated temperature, and finally ζ-phase Cr2(C,N) particles were obtained at the optimal condition of 1200 °C for 1 h under the N2 pressure of 0.02 MPa, which showed lowest oxygen (0.82 wt%) and highest nitrogen (6.25 wt%) content with the diameter of ~ 3 μm. Increasing temperature, N2 pressure, and dwell time facilitates the reduction of oxygen. However, these parameters must be carefully controlled under reasonable ranges to preventing quality deterioration. In addition, the crystal structure of ζ-Cr2(C,N) was characterized by transmission electron microscope and neutron powder diffraction (NPD). Based on the selected area diffraction and NPD patterns, the crystal structure of Cr2(C,N), prepared in this work, was confirmed to be orthorhombic (Pbcn) as well as the interstitial atoms (C and N) were ζ-type occupational ordering.

Decoupled effects of thermal cycle parameters on thermo-mechanical damage accumulation at fingers in crystalline silicon photovoltaic modules

Thermal cycling (TC) is a well-known testing method to assess the durability of photovoltaic (PV) modules towards thermo-mechanical fatigue. Thermal cycle operating parameters viz. ramp rate and isothermal dwell period would cause distinct influence on the thermo-mechanical degradation modes in PV modules. For this purpose, detailed analysis of different parameters of TC test have been investigated using a systematic approach wherein specific modified TC tests have been derived from IEC 61215 standards to decouple their individual effects. The derived tests were subjected on a 3-D finite element model (FEM) of a PV module for quantification of thermo-mechanical damage accumulation at the finger-solder interface, which is most susceptible to such TC variations. The simulated findings were experimentally supported with finger breakages and increase in series resistance obtained under the modified tests, using electroluminescence (EL) imaging and illuminated current-voltage (I-V) technique respectively. This systematic study could isolate the effects of ramp rate and dwell period on the basis of rate and amount of damage accumulation, equivalent test time, and operational feasibility. The major findings in addition to a detailed discussion showed that, a noteworthy decrease in equivalent test time was observed with change in ramp rate. Also, dwell period was identified as an additional key factor for catalysing finger breakages. In addition, isothermal dwell period at low temperatures was identified to be inherently severe for causing finger breakages. Based on this study, the reason behind the delayed generation of finger breakages under field conditions have been discussed using experimentally measured temperature profiles on a PV module under a hot and dry outdoor location. This work can be useful to design application-specific tests by optimization of cycle parameters on the basis of the particular requirements.

Isovolumetric synthesis of chromium carbide for selective laser reaction sintering (SLRS)

A novel synthesis approach for the in-situ formation of isovolumetric non-oxide ceramics was demonstrated for application with selective laser sintering additive manufacturing (SLS-AM) methods. By optimizing the ratio of a metal/metal-oxide precursors system, the conversion of a 86/14 molar Cr/Cr2O3 composite precursor film to Cr3C2 by gas-solid reaction with CH4 was investigated as a model reaction synthesis process. The composite precursor mixture was ball-milled to nano/micro-sizes to enhance gas-phase mass transport for conversion. The feedstock was deposited as a 250 μm thick film representative of a single SLS layer using a high-volume low-pressure spray deposition method. The effects of H2 and trace amounts of oxidizing gas impurities on the reaction thermodynamics of the conversion process and microstructural evolution were investigated. The gas-solid reactions were carried out at 950 °C with an isothermal dwell time of 0.1 h under atmospheres of Ar/H2/CH4 and Ar/CH4. The results suggest that expeditious and thorough conversion of the precursor to Cr3C2 was achieved (greater ≥90 wt% in Ar/CH4 and ≥95 wt% in Ar/H2/CH4). Phase characterization of sample cross-sections using SEM image contrast methods were used to assess apparent volumetric occupancy of the as-deposited Cr/Cr2O3 precursor film and the Cr3C2 product ceramic. Results indicate approximate fill fractions of 81.3% (SD = 1.78) and 78.9% (SD = 1.52) respectively, suggesting near isovolumetric conversion. Ultimately, the results in this model system demonstrate isovolumetric reaction syntheses techniques broadly applicable for in-situ non-oxide ceramic production via selective laser sintering-AM.

Growth and physical properties of top-seeded infiltration growth processed large grain (Gd, Dy)BCO bulk superconductors

The primary prerequisite for successful single grain growth of a REBa2Cu3Oy bulk superconductor is the determination of an optimized growth temperature window of the given system. In our recent work, addition of 20 wt. % of Dy2BaCuO5 (Dy-211) to the GdBa2Cu3O7-δ bulk sample [(Gd,Dy)BCO] enhanced superconducting properties. Then, different isothermal dwell times were tested at various undercooling temperatures to find the temperature window appropriate for the single grain growth by a top-seeded infiltration growth process performed in air. Nearly perfect single-grain (Gd,Dy)BCO crystals were grown. A systematic and detailed investigation of the microstructure, composition, and physical properties of the single-grain (Gd,Dy)BCO superconductors was carried out. The superconducting transition was sharp with the onset at 92.9 K. The field dependence of the critical current density (Jc) was determined at several temperatures. At 77 K, a self-field Jc of 55 kA/cm2 and a trapped field of 0.19 T were achieved. The possibilities for further improvement of the microstructure and superconducting performance are discussed.

Core-rim structure formation in TiC-Ni based cermets fabricated by a combined thermal explosion/hot-pressing process

TiC-Ni-based cermets were obtained by thermal explosion from different elemental mixtures (Ti, C, Ni and X, where X=Cr, Mo or W) and subsequently densified by hot-pressing under a cyclic load. The whole process was performed in a single stage in the same experimental device according to the following thermal and pressure procedure: a heating rate ramp up to 1573K without applying any load followed by an isothermal dwelling under a compressive cyclic load of 32MPa. The thermal explosion synthesis occurred during the heating ramp at a temperature close to 1273K that was practically independent of the starting nominal composition. The influence of different refractory elements on the chemical composition and microstructure of cermets was studied. SEM characterization showed that only with Mo and W, the cermets developed the characteristic core-rim structure. A high densification was achieved, but decreased when the refractory elements were added. Nevertheless, in these cases higher hardness values were obtained.

The Effect of Heat Treatment on the Structure and Mechanical Properties of Austempered Iron with Vermicular Graphite

Austempered vermicular-graphite iron seem to be a perspective material because of its promising mechanical properties. These properties are strongly affected by parameters of applied heat treatment. Different heat treatment conditions (austenitizing dwell time, isothermal temperature and isothermal dwell) were varied and their effect on the structure and mechanical properties was evaluated and described. Properly selected heat treatment conditions lead to formation of ausferritic matrix with which is responsible for substantial increase in mechanical strength while maintaining sufficient ductility.

Liquid plasma sprayed nano-network La0.4Sr0.6Co0.2Fe0.8O3/Ce0.8Gd0.2O2 composite as a high-performance cathode for intermediate-temperature solid oxide fuel cells

Abstract Here, we investigate the feasibility of using a liquid plasma spray process as a novel method for the cost-effective fabrication of a nanonetwork of La 0.4 Sr 0.6 Co 0.2 Fe 0.8 O 3−δ (LSCF) and Ce 0.8 Gd 0.2 O 2−δ (GDC) composite as a high-performance cathode for intermediate-temperature solid oxide fuel cells. A suspension containing well-dispersed nanosized GDC particles in an LSCF precursor solution is designed as the feedstock. The effects of GDC concentration in the suspension on the phase composition, microstructure, and electrochemical performance of the resulting cathode are studied. When the GDC concentration increases to 15 g L −1 , the nanosized GDC particles distribute uniformly and continuously on the LSCF backbone to form a porous network structure. The electrochemical studies further indicate that the cathode polarization decreased with the increase in GDC concentration from 0 g L −1 to 15 g L −1 , whereas a further increase in the GDC concentration increases the cathode polarization instead. At 600 and 750 °C, the cathode prepared using 15 g L −1 GDC concentration exhibits an impressive area-specific polarization resistance (R p ) of 0.1 Ω cm 2 and 0.009 Ω cm 2 , respectively. Finally, the R p of the optimal cathode almost does not change after the isothermal dwelling at 650 °C for 350 h.