•Ta alloying layer are fabricated by magnetron sputtering and high current pulsed electron beam.•Nano-scaled TaC precipitates forms within the δ-Fe grain after tempering treatment.•The mean diameter of TaC particles is about 5–8 nm.•The hardness of alloying layer increased by over 50% after formation of nano-scaled TaC particle.In this study, the combination of magnetron sputtering and high current pulsed electron beam are used for surface alloying treatment of Ta film on high speed steel. And the Ta alloying layer is about 6 μm. After tempering treatment, TaC phase forms in Ta alloying layer when the treated temperature is over 823 K. Through the TEM and HRTEM observation, a large amount of nano-scaled precipitates (mean diameter 5–8 nm) form within the δ-Fe grain in Ta alloying layer after tempering treatment and these nano-scaled precipitates are confirmed as TaC particles, which contribute to the strengthening effect of the surface alloying layer. The hardness of tempered alloying layer can reach to 18.1 GPa when the treated temperature is 823 K which increase by 50% comparing with the untreated steel sample before surface alloying treatment.

•Cr alloying layer is fabricated by combination of magnetron sputtering and high current pulsed electron beam.•The remelted layer contains Fe-Cr solid solution, a small amount of amorphous phase, austenite and martensite.•The microhardness slightly drops and corrosion resistance increases significantly after surface alloying treatment.•The Fe-Cr solid solution contributes to the formation of passive film during corrosion process.The Cr alloying layer was introduced on the steel substrate subjected to surface alloying treatment by combination of magnetron sputtering and high current pulsed electron beam. The microstructure of the Cr alloying layer was studied using SEM, XRD and TEM. The thickness of the remelted layer was about 5 μm after surface alloying treatment. The 2 μm thick Cr-rich layer containing Fe-Cr solid solution and a small amount of amorphous phase was observed at the top of remelted layer after irradiation. The remelted layer also contained columnar austenite grains and plate martensite. The microhardness of Cr alloying layer only dropped slightly comparing with the original steel substrate. However, the corrosion resistance of the specimen after surface alloying treatment was significantly improved and the Fe-Cr solid solution was believed to contribute to the formation of passive film to increase the corrosion resistance.

•Novel Co-free Cu1.4Mn1.6O4 spinel cathode are prepared and evaluated for IT-SOFCs.•CMO shows good thermal and chemical compatibility with ScSZ electrolyte material.•CMO exhibits a low polarization resistance of 0.143 Ω cm2 at 800 °C.•A remarkable power output of 1076 mW cm−2 is achieved at 800 °C.In this work Cu1.4Mn1.6O4 (CMO) spinel oxide is prepared and evaluated as a novel cobalt-free cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). Single phase CMO powder with cubic structure is identified using XRD. XPS results confirm that mixed Cu+/Cu2+ and Mn3+/Mn4+ couples exist in the CMO sample, and a maximum conductivity of 78 S cm−1 is achieved at 800 °C. Meanwhile, CMO oxide shows good thermal and chemical compatibility with a 10 mol% Sc2O3 stabilized ZrO2 (ScSZ) electrolyte material. Impedance spectroscopy measurements reveals that CMO exhibits a low polarization resistance of 0.143 Ω cm2 at 800 °C. Furthermore, a Ni-ScSZ/ScSZ/CMO single cell demonstrates a maximum power density of 1076 mW cm−2 at 800 °C under H2 (3% H2O) as the fuel and ambient air as the oxidant. These results indicate that Cu1.4Mn1.6O4 is a superior and promising cathode material for IT-SOFCs.A novel cobalt-free Cu1.4Mn1.6O4 (CMO) spinel oxide was synthesized and assessed as a potential SOFC cathode. Low polarization resistances for CMO were 0.143 and 0.317 Ω cm2 at 800 and 750 °C, respectively. Furthermore, a remarkable power output of 1076 mW cm−2 is achieved at 800 °C by a Ni-ScSZ anode supported ScSZ electrolyte single cell with the CMO cathode.

•Strontium-site-deficient Sr2Fe1.4Co0.1Mo0.5O6−δ oxides are prepared and evaluated.•The TEC and electrical conductivity values firstly decrease and then increase.•Sr1.950Fe1.4Co0.1Mo0.5O6−δ shows the lowest ASR value of 0.093 Ω cm2 at 800 °C.•A maximum power density of 1.16 W cm−2 is achieved by single cell with S1.950FCM cathode at 800 °C.In this paper strontium-site-deficient Sr2Fe1.4Co0.1Mo0.5O6−δ-based perovskite oxides (SxFCM) were prepared and evaluated as the cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). All samples exhibited a cubic phase structure and the lattice shrinked with increasing the Sr-deficiency as shown in XRD patterns. XPS results determined that the transition elements (Co/Fe/Mo) in SxFCM oxides were in a mixed valence state, demonstrating the small polaron hopping conductivity mechanism existed. Among the samples, S1.950FCM presented the lowest coefficient of thermal expansion of 15.62 × 10−6 K−1, the highest conductivity value of 28 S cm−1 at 500 °C, and the lowest interfacial polarization resistance of 0.093 Ω cm2 at 800 °C, respectively. Furthermore, an anode-supported single cell with a S1.950FCM cathode was prepared, demonstrating a maximum power density of 1.16 W cm−2 at 800 °C by using wet H2 (3% H2O) as the fuel and ambient air as the oxidant. These results indicate that the introduction of Sr-deficiency can dramatically improve the electrochemical performance of Sr2Fe1.4Co0.1Mo0.5O6−δ, showing great promise as a novel cathode candidate material for IT-SOFCs.

In this work NiO/3 mol% Y2O3–ZrO2 (3YSZ) and NiO/8 mol% Y2O3–ZrO2 (8YSZ) hollow fibers were prepared by phase-inversion. The effect of different kinds of YSZ (3YSZ and 8YSZ) on the porosity, electrical conductivity, shrinkage and flexural strength of the hollow fibers were systematically evaluated. When compared with Ni–8YSZ the porosity and shrinkage of Ni–3YSZ hollow fibers increases while the electrical conductivity decreases, while at the same time also exhibiting enhanced flexural strength. Single cells with Ni–3YSZ and Ni–8YSZ hollow fibers as the supported anode were successfully fabricated showing maximum power densities of 0.53 and 0.67 W cm−2 at 800 °C, respectively. Furthermore, in order to improve the cell performance, a Ni–8YSZ anode functional layer was added between the electrolyte and Ni–YSZ hollow fiber. Here enhanced peak power densities of 0.79 and 0.73 W cm−2 were achieved at 800 °C for single cells with Ni–3YSZ and Ni–8YSZ hollow fibers, respectively.

•Multi-element films are prepared by combined magnetron sputtering and PBII.•XPS confirms ZrN, TiN, TaN, Nb–N, ZrO2, Ta, Nb and W in the nitride film.•Multi-element (ZrTaNbTiW)N films formed BCC and FCC phases.•Maximum hardness and elastic modulus of nitride films reached 13.5 and 178.9 GPa.Multi-element (ZrTaNbTiW)N films are prepared by multi-target magnetron sputtering deposition and nitrogen plasma based ion implantation (PBII). The composition, structure and mechanical properties of the films are investigated. X-ray photoelectron spectroscopy (XPS) confirms the formation of a mixture of ZrN, TiN, TaN, Nb–N, ZrO2, Ta, Nb and W in the nitride film. X-ray diffraction (XRD) shows that the (ZrTaNbTiW) alloy film exhibits an amorphous phase, while the (ZrTaNbTiW)N nitride films are composed of BCC and FCC structures. The hardness and modulus of the films are improved significantly after nitrogen PBII and reach maximum values of 13.5 and 178.9 GPa, respectively.

The structure and properties of Ti6Al4V alloy irradiated by high current pulsed electron beam (HCPEB) with various pulse number were studied in this paper. Optical Microscopy (OM) and X-ray Diffraction (XRD) were used to analyze the structure of irradiated layer. It is found that the phase composition transforms from α + β binary phases to single α′-Ti after HCPEB treatment and the grain size reduces to ~ 100 nm. The corrosion resistance of irradiated layers greatly improves in comparison with that of initial state. The hardness and modulus of the irradiated layer were lower than that of initial state, while wear rate of the irradiated layer does not reduce under dry sliding test.Highlights► We processed Ti6Al4V alloy by high current pulse electron beam (HCPEB) of ~ 9 J/cm2. ► The microstructure is changed from two phases to single with grain size of 100 nm. ► Wear resistance of Ti6Al4V is reduced with lowered hardness and modulus slightly. ► The corrosion resistance in physiological saline is obviously improved.

In this work, Cr4Mo4V steel was irradiated by high energy current pulsed electron beam (HCPEB) with energy density of 6 J/cm2. Morphology and phase composition of the surface layer were analyzed using scanning electron microscopy (SEM) and glancing angle X-ray diffraction (GXRD). The crater-like morphology was observed on surface after HCPEB treatment, and the thickness of melted layer was ∼7 μm. Results from GXRD revealed that HCPEB treatment could suppress martensite transition and the content of retained austenite in the melted layer increased with irradiation number. The corrosion resistance was evaluated by electrochemical polarization tests in neutral 3.5% NaCl solution. Compared with the untreated Cr4Mo4V steel, corrosion potential of the samples treated by HCPEB improved and the corrosion current density decreased. The improved corrosion resistance is attributed to the absence of the carbide, formation of retained austenite and dissolution of alloy elements, particularly of Cr and Mo, into the matrix.Research highlights▶ Using high energy pulsed electron beam to modify Cr4Mo4V steel surface properties. ▶ Electron beam irradiation induces crater-like defects on the surface of the steel. ▶ After irradiation, retained austenite formed in the remelted layer of the steel. ▶ Electron beam irradiation improves the corrosion resistance of the steel.

Ti6Al4V alloy was implanted with oxygen by using plasma based ion implantation (PBII) at pulsed voltage ranging from −10 to −50 kV. In order to maintain a lower implantation temperature, an oil cooling working table was employed. The thicknesses of modified layer of samples implanted at −30 and −50 kV are about 117 and 182 nm, respectively. There is crystalline rutile phase in the modified layer of sample implanted at high implanted voltage, but this phase has not detected for sample implanted at low voltage. The hardness of the implanted layer increases with implanted voltage, and the increasing factor of peak hardness reaches 1.6–2.6. The hardening effect exists even at depths larger than the maximum reach of implanted oxygen, as seen by XPS data. In the initial stage of friction, implanted samples have a low friction coefficient comparing with untreated. Wear resistance increases with implanted voltage, and maximum increase from sample implanted at −50 kV reaches two times untreated one. The wear mechanism of implanted samples is abrasive-dominated and adhesive, furthermore the level of adhesive decreases with implanted voltage.

The corrosion behavior of AISI302 steel implanted with nitrogen at elevated temperature was investigated by electrochemical impedance spectroscopy. Equivalent circuits for explaining the impedance characteristics are proposed. The thick passive layer containing Cr2O3 and the expanded austenite layer in the sub-surface worked together, resulting in the high corrosion resistance.