The impact of current density on Cr-poisoning of Sr-doped lanthanum manganite cathode is studied at 750 °C. The presences of SUS430 interconnect alloys cause rapid degradation in LSM cathode performance. The Cr deposits can be found not only on the LSM surface close to the electrode/electrolyte interface, but also on the YSZ surface. The deposition area is reach to 4.1 μm from the electrode/electrolyte interface after cathodic polarization with a current density of 400 mA cm−2 for 1200 min. TEM results clearly demonstrate that the particles on LSM surface are MnCr2O4 spinels, which means that the Cr species would react with Mn from LSM and then lead to the structural damages of LSM cathode. A high polarization current of 800 mA cm−2 significantly accelerates Cr deposition process, resulting in a wider deposition area of 5.9 μm on LSM surface. The present results show that the Cr deposition occurs beyond the electrolyte/electrode interface, which reveals that the deposition of Cr species is driven by chemical reaction, not electrochemical reduction. Cr species are induced to deposit on LSM cathode surface by chemical reaction with Mn2+ ions, and extend to YSZ surface under cathodic current.

•The oxidation behavior of coated SUS430 is investigated in dual atmosphere.•The coating is served as barrier to depress Cr evaporation from interconnect alloy.•The performance of LSM cathode is stable when coating was applied.The MnCu0.5Co1.5O4 spinel coating is proposed as a protective coating for SUS430 alloy to improve its oxidation resistance and prevent chromium vaporization. The coated alloy is exposed to dual atmosphere (Air/H2–3%H2O) at 750 °C for 200 h, exhibiting a stable spinel structure on the air side, but reduced to MnO, Cu and Co on the fuel side. The coating layer could maintain integrated and dense with a thickness of 13–14 μm. The experiment results shown that the MnCu0.5Co1.5O4 coating is an effective diffusion barrier that can inhibit oxidation and chromium vaporization of metallic interconnect. The relatively low amount of Cr deposition on LSM cathode on coated condition is considered associating with the stable electrochemical performance under current density of 400 mA cm−2. The above results indicate that MnCu0.5Co1.5O4 spinel is a promising coating for interconnect alloy of solid oxide fuel cell.

•Pd0.95Mn0.05O-infiltrated LSM-YSZ cathode was applied in large size SOFC.•Electrochemical performance of infiltrated cell was significantly improved.•Thermal cyclicability and long-term stability was evaluated at 750 °C.•The relativity between particle growth and performance degradation was discussed.Pd0.95Mn0.05O-infiltrated (La0.8Sr0.2)0.95MnO3−δ–8 mol.% Y2O3 stabilized ZrO2 (LSM-YSZ) cathode is used to large size (11 × 11 × 0.1 cm) Ni-YSZ anode-supported planar cells for the first time and electrochemically evaluated in the intermediate temperature range from 650 to 800 °C with H2 as the fuel and air as the oxidant. The initial open circuit voltage (OCV) of the cell is 1.15 V, and the achieved maximum power density increases from 328 to 734 mW cm−2 with the increase of testing temperatures from 600 to 800 °C, which is almost 2.6 times higher than that of the cell with conventional LSM-YSZ cathode. After each thermal cycle between 750 and 300 °C, the OCV remains almost unchanged and the cell voltage decreases less than 0.007 V, indicating that the cell is capable of thermal cycling. The cell voltage at 310 mA cm−2 and 750 °C declines linearly with testing time at a rate of 2.6 × 10−4 V h−1 for the growth of the infiltrated Pd0.95Mn0.05O size, resulting in reduction of the total surface area of the particles. The mechanism of performance degradation of the cell with Pd0.95Mn0.05O-infiltrated LSM-YSZ composites cathode is discussed in detail.

•A Mo contained interconnect alloy exhibited less Cr deposition on cathode.•LSM with Mo alloyed interconnect showed better electrochemical performance.•The formation of MnMoO4 and MoO3 can alleviate the Cr poisoning of cathode.The effect of addition of molybdenum in FeCrMn based alloy on the chromium deposition and poisoning of LSM cathodes is investigated at 800 °C by electrochemical impedance spectroscopy and microstructure analysis. The FeCrMnMo ferrite stainless steel metallic interconnect shows much less Cr deposition and poisoning on the LSM cathodes as compared with the FeCrMn alloy. The addition of Mo into the alloy suppressed Cr evaporation from interconnects, decreased the degradation of cathode performance caused by Cr. According to SEM results, MoO3 and MnMoO4 is observed at the depositional area. The segregated MnO from LSM cathode can act as a nuclei agent, and react with vaporized Mo to form Mo-contained oxide particles, which will not inhibit the oxygen reduction reactions in the three phase boundary (TPB). As a result, suitable addition of Mo into the interconnect alloy can effectively alleviate the Cr poisoning of the LSM cathode.

•SSM presents lower Cr caused degradation rate.•Cr deposition on the surface of SSM is SrCrO4.•Cr deposition is on surface under OCP and edge of SSM under cathodic current.Strontium-doped samarium manganite is a potential cathode for solid oxide fuel cells (SOFCs) with remarkable high oxygen reduction reaction activity. Here we investigated chromium poisoning effect on Sm0.5Sr0.5MnO3 cathode of SOFCs for the first time. The Cr caused cathode degradation is studied under current density of 200 mA cm−2 and open circuit potential (OCP) at 750 °C. After polarized in the presence of the Crofer22 APU at 750 °C for 1200 min, the polarization resistance decreases from 3.25 Ω cm2 to 2.25 Ω cm2, then increases to a stable value of 2.75 Ω cm2. The degradation rate of SSM is lower than that of LSM cathode in the same experimental environment. At OCP, the polarization resistance increases to 7.00 Ω cm2 and reaches a stable level. SEM and EDX shows the depositions on the Sm0.5Sr0.5MnO3 boundary after applying current for 1200 min, and on the SSM surface after aging at OCP for 200 h. The Cr depositions are mainly comprised of SrCrO4 formed by the nucleation reaction. The results show that SSM is a poisoning tolerant cathode and good replacement for the LSM in IT-SOFCs due to the better electrochemical performance and the relatively stable characteristics after Cr poisoning.

•A flexible ceramic-glass composite seals was developed by tape casting technique.•The optimized AD40 composite seals demonstrated an excellent gas tightness and deformability.•The cell used AD40 seals maintained high performance and low degradation rate.The ceramic-glass was employed as the most commonly used seal materials in planar solid oxide fuel cell (SOFC). In this study, a novel glass with relative low glass soft temperature was added into Al2O3 powders to form ceramic-glass composite seals by tape casting technique. Based on the tested result of gas tightness and compressibility, it was found that the seals with 40 wt% glass exhibited excellent seal performance at the leakage rates of only 0.01 sccm.cm−1 under gas pressure of 10.2 kPa, and compressive load of 0.17 MPa at 750 °C. The seals showed the desired thermal cycle stability at low leakage rates within 10 thermal cycles. It can be observed that the deformability of seals sharply increase when the glass contents was higher than 30 wt%. Microstructural analysis of the seals also exhibited very good interfaces bondage and chemical compatibility which was in good agreement with gas tightness prediction for the flexible ceramic-glass seals model. The seals have been applied in large size cell test to confirm its applicability in SOFC.

•MnCu0.5Co1.5O4 coating for SUS430 is evaluated in cathode and anode atmosphere.•MnCu0.5Co1.5O4 coating is stable in cathode with ASR of 0.343 mΩ cm2 after 1000 h.•MnCu0.5Co1.5O4 coating will be decomposed in anode with a high ASR.In order to improve the performance of SUS 430 alloy as a metallic interconnect material for intermediate-temperature solid oxide fuel cell (IT-SOFC), a low-cost and Cr-free spinel coating of MnCu0.5Co1.5O4 on SUS430 alloy substrate by sol–gel method is studied. MnCu0.5Co1.5O4 coated SUS430 alloy is evaluated in the simulated reducing (anode) and oxidizing (cathode) SOFC working environments at 750 °C for 1000 h about the microstructure, oxidation resistance and electrical conductivity. The result confirms that the spinel coating shows electrical conductivity of 105.5 S cm−1 at 750 °C in air and an average CET value of 12.27 × 10−6 K−1 at temperature range of 20–1000 °C. The coating layer is identified as MnCu0.5Co1.5O4 in cathode, and MnO, Cu and Co in anode atmosphere. And the thickness of the oxidized scale is around 7–8 μm after 1000 h of oxidation in both situations. The dense coating layer is effective in blocking the Cr migration/transport and depressing the growth of Cr2O3 and formation of MnCr2O4. In cathode atmosphere, the oxidation kinetics obeys the parabolic law with a rate constant as low as 1.77 × 10−15 g2 cm−4 s−1 and the ASR contributed by the oxide scale is 0.3 mΩ cm2. In anode atmosphere, the Δm/A of MnCu0.5Co1.5O4 coated SUS430 alloy is 0.2 mg cm−2 for 1000 h. Generally, the overall performance of the MnCu0.5Co1.5O4 coated SUS430 alloy is superior to those of bare SUS430 and other ferritic candidate alloys.

•A novel Fe–Cr based interconnect alloy containing molybdenum exhibited less Cr poisoning effect on LSM cathode of SOFC.•The alloy containing molybdenum revealed narrow oxide deposition zone due to Cr volatilization reduced.•The mechanism of Cr poisoning LSM cathode has been demonstrated on two kinds of ferritic stainless steel as interconnect.A newly developed interconnect alloy for solid oxide fuel cells, containing Fe, Cr, Mn and Mo as well as other minor elements and designated as FeCM, is investigated on its poisoning effect on (La0.8Sr0.2)0.95MnO3−δ (LSM) cathode by electrochemical impedance spectroscopy and microstructure observation. Compared with commercial SUS430 stainless steel, which is usually used as a essential interconnect in the SOFCs stacks, the FeCM alloy as the interconnect reduces the ohmic of the cell (RΩ) and polarization resistance of the cathode (RP) and increases the electrochemical performance of the cathode. At 850 °C the RΩ remains almost unchanged at a level slightly above 2.0 Ω cm2 and the RP decreases from 5.76 to 1.68 Ω cm2 within 20 h, while the cathode potential at 200 mA min−1 is virtually stabilized at below 1.0 V and the overpotential is decreased from 0.43 to 0.16 V. Based on the evidence of a narrower oxide deposition zone on the electrolyte surface near the cathode and a deposition-free cathode/electrolyte interface, this improvement is attributed to the reduced degree of volatilization of oxide scale formed on the surface of the FeCM alloy.

Perovskite Sm0.5Sr0.5MnO3 (SSM55) material is prepared via the sol-gel method, and its crystal structure, chemical stability, thermal expansion coefficient (TEC), and electrical conductivity are characterized. The electrochemical performance of a SSM55 cathode on 8 mol % Y2O3 stabilized ZrO2 (8YSZ) electrolyte is evaluated by electrochemical impedance spectroscopy in the temperature range between 650 and 800 °C, and compared to a La0.8Sr0.2MnO3 (LSM82) cathode. The SSM55 is thermally stable at temperatures up to 1400 °C with a TEC of 10.7 × 10−6 K−1 in the temperature range between 20 and 800 °C, and its electrical conductivity varies from 64 to 138 S cm−1 between 300 and 800 °C. The polarization resistance of SSM55 cathode on 8YSZ electrolyte is determined as 64.98, 39.44, 8.67 and 1.92 Ω cm2 at 650, 700, 750 and 800 °C respectively, which is significantly lower than that of a LSM82 cathode at temperatures above 700 °C. To further increase the electrochemical performance of the cathode, SSM55-8YSZ composite cathode was obtained with a polarization resistance of 1.08 and 0.45 Ω cm2 at 750 and 800 °C, respectively. These values are considerably lower than that of a LSM82-8YSZ cathode, suggesting that the SSM55 is a promising cathode material for intermediate temperature solid oxide fuel cells operated at 750 °C and above.

•Effects of current polarization on performance degradation were revealed by XPS.•Performance activation occurs at the beginning stage of current polarization.•Current treatment enhances the activity of Co in the LSCF lattice.The stability of La0.6Sr0.4Co0.2Fe0.8O3−δ impregnated Y2O3 stabilized ZrO2 (LSCF–YSZ) cathodes was investigated under the condition of open circuit or current polarization at 750 °C in air. The electrochemical measurement and the microstructure characteristic show that the flattening of LSCF particles has great contribution to the increase of resistance of LSCF–YSZ cathodes after 500 h heat treatment at 750 °C. Microstructure coarsening and the damage of well-connected porous structure are main reasons of the performance degradation for LSCF–YSZ cathodes testing at 200 mA cm−2 and 750 °C in air. Higher current density of 500 mA cm−2 applying on cathodes accelerates degradation processes. X-ray photoelectron spectroscopy (XPS) shows that Sr concentration on the cathode surface decreases after current polarization, which plays a main role in performance activation processes observed at the beginning stage. The enhancement of cobalt activity in LSCF lattice by current polarization increases the conductivity and decreases the stability of LSCF–YSZ cathodes.

A 3-cell stack of anode supported planar solid oxide fuel cell was built to evaluate the application of an external-manifold design in this research. This short stack was operated with hydrogen as fuel and air as oxidant at 750 °C. The stack had an OCV of 3.36 V, produced about 100 W in total power with a power density of 0.56 W/cm2. The stack also underwent 51 h degradation test at the current density of 0.55 A/cm2. The test results have demonstrated that this external-manifold stack had an excellent and steady performance during the test. Computer simulation was employed to help optimizing the parameters of the design and explaining the different performances between the cells. The simulation results suggested that the external-manifold design could generate a uniform gas distribution for a short stack, and the different performances of the individual cells were mainly caused by the uneven temperatures distribution between the cells.Highlights► A prototype 3-cell external-manifold SOFC short stack is built. ► The stack exhibits an OCV of 3.36 V and power density of 0.56 W/cm2. ► Slow decay rate is shown in the performance and degradation test. ► Computer simulation was used to optimize the flow and temperature distribution.

The Cr deposition reaction is investigated between the La0.9Sr0.1MnO3 (LSM) cathode and Fe–Cr alloy interconnect at 750 °C for solid oxide fuel cell. The poison effect on cathode is observed by a group of orthogonal experiments at the presence of Fe–Cr alloy involving with air flow and current passages. After the current polarization, the cathode layer has been delaminated from the electrolyte (YSZ), and the Cr deposition reaction is accelerated with adding air partial pressure. When the LSM cathode has undergone Cr poison for 3000 min with current passage of 400 mA cm−2 and air flow of 100 mL min−1, two rapid increase stages of polarization potential Ecathode are found, which can be reasonably explained by Cr deposition resulting in cathode delaminated from the electrolyte layer. Furthermore, the Cr deposition ring and two kinds of Cr-contain agglomerates are observed in the interface of LSM/YSZ, which indicates that the formation of Cr2O3 and (Cr,Mn)3O4 oxides, respectively. This suggests that the deposition of Cr species would preferentially occur at the three phase boundary region and the trend to agglomeration in long time operation.Highlights► Interaction of LSM cathode/Fe–Cr alloy was characterized at 750 °C. ► The Cr deposition on LSM cathode would be accelerated under air flow. ► The cathode layer is delaminated from the YSZ under the current polarization. ► Two kinds of congregated Cr sediments were found and the composition was confirmed.

Novel glass-based composite seals prepared by tape casting are evaluated as sealing materials in solid oxide fuel cell. The leakage rates are measured at the inlet pressure of 1, 2 and 3 psi under different compressive stresses and temperatures respectively. The results show that all of measured leakage rates are lower than 0.01 sccm cm−1 and increase with higher inlet pressure and lower test temperatures. The leakage rates during thermal cycling are conducted under a compressive stress of 20 psi at 750 °C, which indicate excellent thermal cycle stability of the seals. Good compatibility between seals and the adjacent components provide well interface contact which could avoid the formation of leakage paths. When the seal is applied for single cell testing, the open circuit voltage of 1.13 V and undetectable degradation clearly demonstrate the applicable performance of glass-based composite seal in solid oxide fuel cell.Highlights► Novel glass/ceramic composite seals exhibited excellent gas tight and chemical compatibility. ► The leakage rates of the seals were lower than 0.01 sccm cm-1 within 25 thermal cycles. ► The seals can maintain well interface compatibility and adhesion after test. ► The feasibility of the seals applied on SOFC was confirmed by single cell test.

In an effort to improve the performance of SUS 430 alloy as a metallic interconnect material, a low cost and Cr-free spinel coating of NiMn2O4 is prepared on SUS 430 alloy substrate by the sol–gel method and evaluated in terms of the microstructure, oxidation resistance and electrical conductivity. A oxide scale of 3–4 μm thick is formed during cyclic oxidation at 750 °C in air for 1000 h, consisting of an inner layer of doped Cr2O3 and an outer layer of doped NiMn2O4 and Mn2O3; and the growth of Cr2O3 and formation of MnCr2O4 are depressed. The oxidation kinetics obeys the parabolic law with a rate constant as low as 4.59 × 10−15 g2 cm−4 s−1. The area specific resistance at temperatures between 600 and 800 °C is in the range of 6 and 17 mΩ cm2. The above results indicate that NiMn2O4 is a promising coating material for metallic interconnects of the intermediate temperature solid oxide fuel cells.Highlights► A preferred microstructure of the oxide scale formed during oxidation at 750 °C in air for up to 1000 h. No Cr-containing oxide is directly exposed to air, which will depress the Cr evaporation. ► An improved oxidation rate 5.0 × 10−15 g2 cm−4 s−1 of the coated SUS 430 alloy. ► An reduced electrical resistance of the coated SUS 430 alloy oxidized at 750 °C in air for 1000 h. In the temperature range of 600–800 °C, the area specific resistance is between 6 and 17 mΩ cm2.

Four Fe–17Cr alloys with various Mn contents between 0.0 and 3.0 wt.% are prepared for investigation of the effect of Mn content on the oxidation behavior and electrical conductivity of the Fe–Cr alloys for the application of metallic interconnects in solid oxide fuel cells (SOFCs). During the initial oxidation stage (within 1 min) at 750 °C in air, Cr is preferentially oxidized to form a layer of Cr2O3 type oxide in all the alloys, regardless the Mn content, with similar oxidation rate and oxide morphology. The subsequent oxidation of the Mn containing alloys is accelerated caused by the fast outward diffusion of Mn ions across the Cr2O3 type oxide layer to form Mn-rich (Mn, Cr)3O4 and Mn2O3 oxides on the top. After 700 h oxidation a multi-layered oxide scale is observed in the Mn containing alloys, which corresponds to a multi-stage oxidation kinetics in the alloys containing 0.5 and 1.0 wt.% of Mn. The oxidation rate and ASR of the oxide scale increase with the Mn content in the alloy changes from 0.0 to 3.0 wt.%. For the application of metallic interconnects in SOFCs, Mn-free Fe–17Cr alloy with conducting Cr free spinel coatings is preferred.Highlights► Fe–17Cr alloys with various Mn contents between 0.0 and 3.0 wt.% are prepared as candidate materials for interconnects of solid oxide fuel cells. ► Cr2O3 is preferentially formed within 1 min of oxidation at 750 °C in air in all alloys; multi-layered oxide scale is observed. ► Oxidation rate increases with Mn content, resulting higher ASR. ► Mn-free Fe–17Cr alloy is preferred in terms of oxidation and conductivity.

Pd-Y2O3 stabilized ZrO2 (YSZ) composite cathodes are prepared by conventional mechanical mixing and infiltration methods. In the case of infiltration, thermal decomposition and chemical reduction processes are used to form Pd particles on the YSZ scaffold. The phase structure, morphology and electrochemical performance of the Pd-YSZ composite cathodes are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and electrochemical impedance spectroscopy (EIS). The performance of mechanically mixed Pd-YSZ composite cathodes is inadequate due to significant growth and sporadical distribution of Pd particles. The 5 wt.% Pd-loaded cathode prepared by infiltration-thermal decomposition process shows the lowest polarization resistance, i.e. between 0.042 Ω cm2 and 1.5 Ω cm2 in the temperature range of 850–600 °C, benefited from the formation of nano-sized Pd particles and the presence of well connected Pd network. The effect of Pd loading on the performance of the infiltrated-thermal decomposed Pd-YSZ composite cathodes is also evaluated, 5 wt.% Pd loading results in the lowest polarization resistances.Highlights► Pd-YSZ composite cathodes were prepared by conventional mechanical mixing and infiltration methods. ► Thermal decomposition and chemical deposition processes were used to obtain Pd particles. ► Infiltrated Pd-YSZ composite cathode prepared from thermal decomposition shows the lowest area specific resistances because of the formation of nano-sized Pd particles and presence of well connected Pd network. ► The Pd-YSZ cathode with 5 wt.% Pd shows the lowest ASR. ► The mechanism of oxygen reduction reaction on Pd-YSZ cathode is discussed.

Anode-supported planar solid oxide fuel cells (SOFCs) with dimension from 5 × 5 cm2 to 15 × 15 cm2 have been successfully fabricated by tape casting, screen-printing and single-step co-firing technologies, which shows a potential way of cost-effective for mass production. The performance of the cells has been investigated at operating temperature between 650 °C and 750 °C. The typical cell with dimension of 10 × 10 cm2 (active reaction area of 9 × 9 cm2) obtained open circuit voltage (OCV) of 1.15 V and power density of 770 mW/cm2 at current density of 950 mA/cm2 at 750 °C. The performance degradation of the cell is lower than 1.56%/1000 h. When external reformed methane gas was used as fuel, the cell showed no obvious performance decrease compared to that using pure hydrogen as fuel. The test results have demonstrated that the as-prepared large size cells have excellent performance and reliability, which is ready for SOFC stack assembly.

Al2O3-based compressive seals were fabricated by tape casting with Al2O3 and 0–30 wt% aluminum powders, and their sealing effectiveness, thermal cycle stability between 200 and 750 °C and applicability in planar intermediate temperature solid oxide fuel cells were evaluated. The results indicate that increasing the aluminum content from 0 to 30 wt% in the seals decreases the leakage rate and increases the thermal cycle stability under various inlet gas (N2) pressures of 3.5, 7.0 and 10.5 kPa. Especially, with the seal containing 30 wt% of aluminum (ACS3), the initial leakage rate was below 0.03 sccm cm−1 under an inlet pressure of 10.5 kPa, and the leakage rates during 96 thermal cycles were below 0.04 sccm cm−1 under the same inlet gas pressure. The interfaces in the interconnect/seal/cell assembly with the ACS3 seal retained integrity after 50 thermal cycles, demonstrating the applicability of the Al2O3-based compressive seals in the planar intermediate temperature SOFCs.

The oxidation behavior and electrical property of a newly designed Fe–Cr alloy with addition of 1.05 wt.% Mn, 0.52 wt.% Ti, 2.09 wt.% Mo and other elements, such as La, Y and Zr have been investigated isothermally or cyclically at 750 °C in air for up to 1000 h. With a coefficient of thermal expansion matched to SOFC cell components, the alloy demonstrates excellent oxidation resistance and low area specific resistance of the oxide scale. The thermally grown oxide scale presents a multi-layered structure with conductive Mn–Cr spinel in-between the underneath Cr2O3 and the top Mn2O3. The oxidation rate constants obtained under both isothermal and cyclic oxidation condition are in the range of 5.1 × 10−14 to 7.6 × 10−14 g2 cm−4 s−1, and the measured area specific resistance at 750 °C after 1000 h oxidation is around 10 mΩ cm2, lower than that of the conventional Fe–Cr stainless steels and comparable with that of the Ni-based alloys. Thermal cycling seems to improve the oxide scale adherence and promotes the formation of the highly conductive Mn2O3, and in turn, to enhance the oxidation resistance and electrical property.

Anode-supported planar solid oxide fuel cells (SOFCs) with an active area of 81 cm2 (9 cm × 9 cm) and nano-structured La0.6Sr0.4Co0.2Fe0.8O3−δ + Y2O3 stabilized ZrO2 (LSCF + YSZ) composite cathodes are successfully fabricated by tape casting, screen printing, co-firing and solution impregnation, and tested using H2 fuel and air oxidant at various flow rates. Maximum power densities of 437 and 473 mW cm−2 are achieved at 750 °C by loading 0.6 and 1.3 mg cm−2 of LSCF in the composite cathodes, respectively. The gas flow rates, particularly the air, have a significant effect on the cell performance. Cell performance degradation with time is also observed, which is considered to be associated with the growth and coalescence of the nanosized LSCF particles in the composite cathode. The use of the LSCF cathode in combination with YSZ electrolyte without a Gd-doped CeO2 (GDC) buffer layer is proved to be applicable in large cells, even though the thermal stability of the nanosized LSCF needs to be further improved.

The NiCo2O4 spinel coating is applied onto the surfaces of the SUS 430 ferritic stainless steel by the sol–gel process; and the coated alloy, together with the uncoated as a comparison, is cyclically oxidized in air at 800 °C for 200 h. The oxidation behavior and oxide scale microstructure as well as the electrical property are characterized. The results indicate that the oxidation resistance is significantly enhanced by the protective coating with a parabolic rate constant of 8.1 × 10−15 g2 cm−4 s−1, while the electrical conductivity is considerably improved due to inhibited growth of resistive Cr2O3 and the formation of conductive spinel phases in the oxide scale.