In this work, thermally sprayed sustainable coatings with spray additives recycled from dry alkaline batteries and solid-oxide fuel cells are developed to allow the growth of drought-resistant plants like moss, microclover and chamomile. It is assumed that these plants anchor to the coating with their rhizoids and hence can be grown without the presence of soil. Preliminary tests of a thermally sprayed Yttrium Stabilized Zirconia (YSZ) ceramic coating on sheet metal confirms the growth of chamomile plant.

The previous results have shown that dense bismuth oxidebased electrolytes can be fabricated simply by plasma spraying owing to their low melting point. In this study, the Bi 2 O 3 – Er 2 O 3 –WO 3 electrolyte of high ionic conductivity was deposited by the cost-effective plasma spraying to assemble the SOFC for examining its electrochemical performance. The SOFC cell consisted of FeCr 24.5 metal support, NiO-YSZ anode, 10 mol% scandium oxide-stabilized zirconium oxide (ScSZ) electrolyte, (Bi 2 O 3 ) 0.705 (Er 2 O 3 ) 0.245 (WO 3 ) 0.05 (EWSB) electrolyte, and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 (LSCF) cathode. The ScSZ electrolyte interlayer was introduced between the anode and EWSB electrolyte to hinder the reduction of EWSB in the anode environment. NiO-YSZ, ScSZ, EWSB, and LSCF were deposited by plasma spraying on the metal support which was prepared by a press-forming-sintering process. The NiO-YSZ/ ScSZ/ EWSB/ LSCF single cell assembled with the as-sprayed ScSZ presented an open circuit potential of 0.90V at 600 °C and the maximum power density of 1130 mW cm -2 at 750 °C, 450 mW cm -2 at 650 °C, and 128 mW cm -2 at 550 °C. The plasma sprayed ScSZ electrolyte was then densified through impregnating using yttrium and zirconium nitrate solutions followed by annealing treatment. The single cell assembled with the densified ScSZ presented an open circuit potential up to 1.004V at 600 °C and the maximum power density of 1356 mW cm -2 at 750 °C, 619 mW cm -2 at 650 °C, and 163 mW cm -2 at 550 °C. The performance of the cell was significantly improved by the post-spray densification treatment of the ScSZ electrolyte. The present result shows that the high performance NiO-YSZ/ScSZ/EWSB/LSCF cell at intermediate temperatures can be successfully fabricated by plasma spraying.

A solid oxide fuel cell is an electrochemical conversion device that produces electricity directly from oxidizing a fuel. It involves ionic transport and electrochemical reactions where the electrolyte and electrode properties play a major role in performance, along with a range of complementary materials that need to ensure equally relevant functions across the cell. The lifetime of such functional materials is expected to reach many thousands of hours with minimal degradation. This article is centred around the process development, optimization and scale up of a thin plasma sprayed ceramic barrier layer to mitigate long-term performance degradation of metal-supported solid oxide fuel cells. The evolution from the proof of concept in a laboratory environment to the scale up toward large scale manufacturing production is discussed. The challenges associated with minimizing application time and lowering cost while maintaining high coating performance at high yield are discussed. Empirical observations such as microstructural analysis and in-flight particle monitoring are used to gain understanding of the plasma spray process and guide its development for high-volume production. Results show how this effort has led to the reduction of the coating deposition time by 94% to enable large-scale manufacturing at high yield.

Stabilized bismuth oxide with fluorite structure is considered a promising electrolyte material for intermediate temperature solid-oxide fuel cells (SOFCs) due to its high oxygen ion conductivity. The ternary system, Bi2O3-Er2O3-WO3, is of particular interest because it is ionically conductive as well as thermally stable. This study investigates the quality of Bi2O3-Er2O3-WO3 (EWSB) electrolyte produced by plasma spraying. The phase structure and cross-sectional microstructure of plasma-sprayed EWSB were characterized by XRD and SEM. The as-sprayed EWSB was found to have a dense microstructure with well bonded lamellae. XRD analysis showed the formation of EWSB with δ-phase and a trace of β-phase, while the β-phase disappeared after annealing at 750°C for 10h. Electrical property tests revealed that the plasma-sprayed electrolyte also had excellent ionic conductivity (0.26 S cm-1 at 750 °C), making it a strong candidate for use in SOFCs at intermediate temperatures.

This study investigates the effect of deposition temperature and particle size on lanthanum strontium chromite (LSC) deposits produced by atmospheric plasma spraying. The results show that dense deposits with lamellar interface bonding can be achieved at temperatures above the critical bonding temperature and that particle size has a significant effect on chromium vaporization losses. The loss of chromium may be responsible for the low electrical conductivity of LSC deposits produced from small powders, which suggests that conductivity can be controlled with appropriate process adjustments.

This study assesses the potential of scandia-stabilized zirconia (ScSZ) produced by very low-pressure plasma spraying (VLPPS) for metal-supported solid oxide fuel cell (MS-SOFC) applications. To investigate the microstructure of ScSZ, coating samples were deposited at spraying distances of 150, 250, 350 mm. The fragile nature of coating cross-sections suggests that the typical lamellar structure of zirconia is replaced by a transgranular structure. Nonetheless, apparent porosity, ionic conductivity, open circuit voltage, and ohmic resistance measurements indicate that VLPPS is a viable method for producing MS-SOFCs.

Ni-Co-Al-Li oxide (NCAL) is an important catalyst material for low-temperature solid oxide fuel cells (LTSOFCs). In this paper, air-plasma spray (APS) coating technology was applied to make NCAL layers on porous steel supports for the LTSOFC. The results showed that NCAL was well deposited on the skeletons of the support. Due to the plasma heating, the original LiMO 2 phase transferred to Li-deficient Li 0.4 M 1.6 O 2 phase simultaneously forming Li-rich oxide. New fuel cell structures were designed. The stability of the fuel cells was evaluated by performing galvanostatic test at 500 °C. The influence of the cell structures and quality on the electronic property of the cells was discussed.

High manufacturing costs and long-term degradation are the main problems that have become a “bottleneck” and impeded SOFC’s further development. It is well known that a high operating temperature is the major cause that leads to these problems. As such, reducing the operating temperature becomes a hotspot of research. It has been reported that a uniform and dense coating can be prepared by using very low pressure plasma spraying (VLPPS) technology. The current study focuses on VLPPS for application in large-area (~100 × 100 mm) porous metal supported solid oxide fuel cell (MSSOFC), especially for the preparation of the electrolyte. It was found that the densification of the electrolyte was very good, as confirmed by the open-circuit voltage (OCV) of the cell. In the temperature range of 550~750°C, the OCV of the cell stabilized between 1.05 V and 1.1 V. The power density of the cell was also measured.

Solid oxide fuel cell (SOFC) has been developed for a hundred year and met a great challenge on material design and marketing. In recent years, new SOFC materials are dug up to achieve high energy-output performance at lower working temperature (300~600 °C), namely low-temperature SOFC (LTSOFC). In this study, Ni-Co-Al-Li oxide (NCAL) was used for making dense, thin and uniform coatings on grooved bipolar electrode substrate for LTSOFC. Low-pressure plasma spray (LPPS) technology was applied to manufacture the NCAL coatings. The performance of a fuel cell package using the coated bipolars was tested between 350 and 600 °C, showing 6~8 W power output with 4 single fuel cells (active area of 25 cm 2 ). The LPPS technology is believed to be one of the ultimate ways for manufacturing the thin film/coatings for SOFC applications in future.

In this work, liquid plasma spraying is used to deposit composite coatings for potential use as cathodes in intermediate-temperature solid oxide fuel cells. A suspension containing well-distributed Gd-doped ceria (GDC) nanoparticles in a lanthanum strontium cobalt ferrite precursor solution was used as the feedstock, and GDC concentration was varied to study its effect on phase composition, microstructure, surface morphology, and electrochemical performance. The results are presented and discussed.

Tubular asymmetric LSCF oxygen transport membranes (OTMs) were prepared on stainless steel substrates by PS-PVD and supersonic air-gas plasma spraying (SAPS). The microstructure of the thermally sprayed OTMs is examined by cross-sectional imaging and oxygen permeability is assessed via oxygen permeation flux measurements carried out at atmospheric pressure in an air-helium gradient. The findings from the cross-sectional analysis and oxygen permeation tests are reported and discussed.

Lanthanum gallate doped with strontium and magnesium (LSGM) is a good electrolyte candidate for Intermediate-temperature solid oxide fuel cells (IT-SOFCs). In this study, low-temperature sintering is used to increase the density of LSGM coatings prepared by vacuum cold spraying (VCS). LSGM layers with different thickness were deposited by VCS on NiO-YSZ substrates. In order to suppress chemical reactions between Ni and LSGM, the substrates were coated with gadolinium-doped ceria by tape casting. After sintering at 1200 °C, the coatings were found to be denser in most regions due to grain growth, which appears to be accompanied by cracking, particularly in thicker layers. A second layer was deposited on the annealed coatings to seal the cracks and the two-layer structure was further sintered. Gas permeability test results show that the multilayer films are dense enough to consider their use as electrolyte membranes in IT-SOFCs.

LSCF(La 0.6 Sr 0.4 Co 0.2 Fe0 .8 O 3 ) with a perovskite structure has been widely studied as cathode materials for intermediate solid oxide fuel cell(SOFC). It has well-known excellent electrode performance due to its high ionic and electronic conductivity. However, application of LSCF cathode is likely to be limited by the surface catalytic properties and long term stability. Sr and Co may segregate from LSCF under cathode polarization, leading to increased resistance of the cathode. Oxygen hyper-stoichiometric La 2 NiO 4+δ with a K 2 NiF 4 structure possesses a higher catalytic properties, ionic conductivity and stability compared to LSCF cathode. However, the electrical conductivity of the La 2 NiO 4+δ (76 S cm –1 at 800 °C ) in the IT range are lower than 100 S/cm, which is regarded as the minimum requirement in electrical conductivity for an SOFC cathode. Taking account of both the advantages and disadvantages of the two different cathode materials, and good chemical compatibility of those two cathode materials, it is possible to prepare a composite cathode by infiltrating a thin film of La 2 NiO 4+ä on the porous LSCF to enhance the LSCF cathode performance. Therefore, in this study, the LSCF cathode was deposited by atmospheric plasma spray. The porous LSCF cathode was infiltrated by La 2 NiO 4+δ . The microstructure was characterized by SEM and TEM. The effect of infiltration on the polarization of LSCF cathode was investigated.

The current paper reports self-healing plasma sprayed Mgspinel (MgAl 2 O 4 ) coatings. The coatings were used for electrical insulation in high temperature fuel cells. A range of potential self-healing additives consisting of SiC+X (where X was BaO, CaO, ZnO, Y 2 O 3 , GeO 2 , Ta 2 O 5 , V 2 O 5 ) were characterized and SiC+Y 2 O 3 was initially selected for coating development. Coatings of spinel with 20wt% additive were developed using vacuum plasma spraying (VPS) or atmospheric plasma spraying (APS). In the developed coatings, self-healing was demonstrated after heat treatment at 1050°C in air for 10 hour. Thermophysical and thermomechanical properties of self-healing coatings were determined and compared to spinel coatings. Lastly, a modelling technique is presented to simulate the effective elastic moduli of the coatings. Numerical results based on microstructural simulations showed good agreement with experimental data.

Based on the specific structure of tubular solid oxide fuel cell stacks, a good chemical, microstructural and phase stability for the protective coating are required in both the oxidizing and reducing environments. In this work, MnCO 2 O 4 coatings of approximately 150 µm were deposited onto porous Ni50Cr50-Al 2 O 3 substrate by atmospheric plasma spray (APS) process. The coated samples were tested at 800°C with the coating exposed in air environment and the substrate in H 2 environment. Reducing and pre-oxidizing treatments were performed prior to the stability test. Then the tested coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD results elucidated that the tested coating had a high structural stability on the upper layer, while presented a reducing microstructure on the substrate side. The surface morphology of 100 hours tested coating indicated that the spinel granules still arranged closely with small particle size of ~ 250 nm and no obvious grain enlargement was observed. According to the cross-section, the upper layer kept stable and dense. While at the underneath region, the microstructure presented to be rather porous. However, the resistance presented a decreasing trend with the extension of exposure duration. After exposure for 95 h, the ASR decreased to 18.5 mΩ·cm 2 although a substantial Cr diffusion from the substrate was detected.

Lanthanum-doped strontium titanate (LST) and samarium-doped ceria (SDC) are promising materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). In this study, LST-SDC composite anodes are produced by suspension plasma spraying and the effects of annealing are assessed. XRD results show that the coatings and powders have the same phase structure. The coatings have a fine porous structure which is beneficial for gas permeability and long three-phase boundaries that facilitate anode reactions. A single cell based on the LST-SDC composite anode was found to perform well at 650-800°C. The results show that annealing improves interface bonding between particles in the anode and at the interface between the anode and electrolyte.

Thermal spray processes are generally employed to deposit dense coatings. The porosity in a thermal spray coating is limited up to about 20% down to less than 1%. The porous abradable coatings can be deposited by using composite powders containing pore-forms such as polymer. Recently, an effective method to deposit porous coating are being developed by directly utilizing semi-melted spray particles through controlling coating surface temperature. In this article, the recent investigations on the deposition of porous materials and ceramic abradable coatings by surface-melted spray particles are reviewed. The bonding formation between particles by controlling deposit surface temperature is essential to form porous deposits. By using flame spraying, different metallic porous deposits up to tens of millimeter thick from refractory molybdenum (Mo) to stainless steel are fabricated with a porosity level up to 70%. Porous alumina (Al 2 O 3 ) and yttria-stabilized zirconia (YSZ) with a porosity of over 60% are deposited for high temperature abradable coating applications directly by semi-molten ceramic particles. The deposition of convex-shaped YSZ particles is employed to construct the high performance structured cathode for solid oxide fuel cell application. Moreover, the deposited convex-shape particles are also utilized to fabricate effective super-hydrophobic surface. The recent progress on the deposition of surface-melted spray particles will enable many new applications for thermal spraying.

The use of ceramic materials in the production of solid oxide fuel cells (SOFCs) is one of the most innovative applications of these materials in recent years. The aim of this work is to assess how to obtain a complete, self-assembled SOFC (supported by electrolyte) using atmospheric plasma spray (APS) to spray the three different ceramic layers of the assembly. One of the main problems of SOFC production is the high cost of the process; the hypothesis is that these costs can be reduced by forming the three ceramic layers of the SOFC by APS technology. The anode (YSZ-NiO), cathode (LSM), and electrolyte (YSZ) layers can be produced by APS with reasonable efficiency. Another problem with SOFC manufacture is assembly and adhesion of the three layers; the creation of gradual transition layers by APS improves these aspects of the production process. Chemical and structural characterization of the feedstock powders and resultant ceramic layers was performed by laser scattering, XRD, SEM, and confocal microscopy, and the results confirmed the efficiency of the attained APS-SOFC components.

Suspension plasma sprayed YSZ coatings were deposited at lab-scale and production-scale facilities to investigate the effect of process equipment on coating properties. The target application for these coatings is SOFC electrolytes, so dense microstructures with low permeabilities were desired. Both facilities had the same torch but different suspension feeding systems, torch robots and substrate holders. These differences meant that the lab facility had higher torch-substrate relative speeds compared to the production facility. When using porous stainless steel substrates with relatively smooth surfaces, permeabilities and microstructures were comparable for coatings from both facilities, and no segmentation cracks were observed. Coating permeability could be further reduced by increasing substrate temperatures during deposition or reducing suspension feed rates. On rougher substrates representative of SOFC cathodes, production facility coatings had higher permeabilities and more segmentation cracks compared to lab coatings. The increased cracking may be due to larger heat impulses with each torch pass at the production facility caused by its lower torch-substrate relative speed. This work highlights some of the challenges associated with scaling up the spray process from the lab to production.

Microstructure of cermet support influences significantly the performance and stability of solid oxide fuel cells (SOFCs). The properties required for the support include high electrical conductivity, necessary permeability, good match of thermal expansion with other layers and high temperature strength. In this study, a porous Ni50Cr50-Al 2 O 3 cermet was designed as the support of SOFC. The porous cermet was deposited by flame spraying with a powder mixture of 30%vol Al 2 O 3 and 35%vol Ni50Cr50 and 35%vol polyester. The effect of cermet microstructure on its gas permeability was investigated. The electrical conductivity, thermal expansion coefficient and bending strength of cermet support were also studied. The results showed that the gas leakage rate of the cermet support increased with the increase of polyester content in the starting powder. The thermal expansion coefficient of the composite cermet decreased with the increase of the volume fraction of Al 2 O 3 . Moreover, the electric conductivity of the cermet increased significantly after high temperature sintering, and reached 1015 S/cm after sintering at 1000°C for 15 hours. The three point bending strength of the Ni50Cr50-based cermet support reached 171 MPa. The cermet stability at high temperatures and SOFCs performance were discussed.