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AlCrTiZrMo high-entropy alloy (HEA) films with strong amorphization were obtained by co-filter cathode vacuum arc deposition, and the effect of thermal shock on the films was investigated in order to explore the protection mechanism of HEA films against mechanical components in extreme service environments. The results show that after annealing at 800 °C for 1 h, the formation of a dense ZrTiO4 composite oxide layer on the surface actively prevents the oxidation from continuing, so that the AlCrTiZrMo HEA film exhibits excellent oxidation resistance at 800 °C in air. In the friction-corrosion coupling environment, the AlCrTiZrMo HEA film annealed at 800 °C for 1 h shows the best tribocorrosion resistance due to the stable dense microstructure and excellent mechanical properties, and its ΔOCP, COF and wear rate possess the smallest values of 0.055, 0.04 and 1.34 × 10−6 mm−3·N−1·m−1. [ABSTRACT FROM AUTHOR]

To alleviate the atomic oxygen (AO) degradation of the polyimide deployed in the low Earth orbit (LEO) environment, we fabricate a set of amorphous TiAlCrZrSi/polyimide films under various negative bias values via the 3rd generation co-filter cathode vacuum arc (C-FCVA). Our rational technical design realizes the noninterference regulation and filtration of mixed multielement plasma compositions. In addition, the atomic size difference (δ , 0.075–0.081), mixing enthalpy (ΔH mix , −48.98 to −46.84 kJ mol−1), and mixing entropy (ΔS mix , 12.83–12.91 J K−1 mol−1) are all within the range of parameters required for the formation of amorphous TiAlCrZrSi high-entropy alloys (HEAs). Moreover, the TiAlCrZrSi/polyimide (no bias) film can realize an equilibrium of AO resistance and durability (E y = 2.02 × 10−26 cm3 atom−1), which is only 0.67 % of that calculated for pristine polyimide. This can be attributed to the excellent AO penetration barrier ability of the generated HEA oxide scales. Furthermore, the thickening of HEA films can reduce the sensitivity of residual defects to AO undercutting erosion, as discussed by the existing empirical theoretical models. [Display omitted] • Fabricated amorphous TiAlCrZrSi/polyimide films by noninterference regulation and filtration of mixed multielement plasmas. • Atomic oxygen erosion yield of the TiAlCrZrSi/polyimide film is 2.02 × 10-26 cm3 atom-1. • The generation of high-entropy alloy oxide scales results in enhanced AO penetration barrier ability. • The thickening of high-entropy alloy films can reduce the sensitivity of residual defects to AO undercutting erosion. [ABSTRACT FROM AUTHOR]

Super-hard and corrosion-resistant (AlCrMoSiTi)N x high-entropy nitride coatings were prepared using a novel multi-arc cathodic vacuum magnetic filtration deposition at different N 2 gas flow rates (R N) of 0, 20, 50 and 70 sccm. The influence of R N on the element composition, phase structure, mechanical, tribological and corrosion properties of the coatings were systematically studied. Higher R N promoted higher N contents in the coatings that resulted in a transformation from an amorphous to face-centered-cubic (FCC) phase. At a high N content of 49 at. % (R N = 70%), the coating exhibits a simple FCC structure, and offers a superior combination of super-hardness, excellent wear and corrosion resistance. The exceptional hardness of the (AlCrMoSiTi)N coating (41.6 GPa) that surpasses most high-entropy ceramics is underlain by the formation of strong metal-nitride phase, the solid-solution strengthening and the fine grain strengthening. Therefore, (AlCrMoSiTi)N x nitride coating presents a potential application in protective coating owing to its extraordinary mechanical properties and corrosion resistance. • AlCrMoSiTi nitride coating prepared by multi-arc cathodic vacuum magnetic filtration. • Effect of N 2 flow rate on structure and properties of coating was studied. • AlCrMoSiTi nitride coatings show a phase structure change from amorphous to FCC. • The AlCrMoSiTi nitride coatings show a super-hard of 41.6 GPa and low wear rate. • Super-hard nitride coating has a low corrosion current density of 2.2 × 10−8 A cm−2. [ABSTRACT FROM AUTHOR]

The AlN monolayer and (Al/AlN)5 multilayer coatings were deposited on AZ31 magnesium alloys by filtered cathodic vacuum arc technology. The AlN monolayer showed a dense structure, but there were some holes at the coating/substrate interface. The (Al/AlN)5 multilayer showed a compact layered structure and the holes were interrupted by the Al/AlN interface. Both AlN monolayer and (Al/AlN)5 multilayer provided excellent corrosion resistance for magnesium alloys, with low corrosion current density of 1.91 × 10−6 and 1.11 × 10−6 A/cm2, respectively. Better corrosion resistance of the (Al/AlN)5 multilayer is attributed to its denser layered structure, better adhesion strength, better crack propagation resistance, and deformation coordination between coating and substrate during corrosion. [ABSTRACT FROM AUTHOR]

A novel four-arc co-filter cathodic vacuum arc deposition technique which was optimized was introduced to deposit (AlCrMoTiV)N x high-entropy alloy nitride films that were corrosion-resistant, high hardness and adhesion. The effect of nitrogen on the microstructure, corrosion resistance and mechanical properties of films was systematically investigated. As the N 2 gas flow rate continues to increase, the phase structure of the (AlCrMoTiV)N x films transforms from a body-centred cubic structure to an amorphous structure, and then to a nanocomposite structure with nano- crystallites embedded in the amorphous matrix. The hardness of the films is proportional to the ratio of N 2 :Ar and reaches maximum (34.08 GPa) at a ratio of 7:4. The adhesion of deposited films was higher than 20 N owing to the bombardment of the substrate by energetic ion beams during the deposition of coatings. The enhanced hardness at higher N contents is mainly gives rise to the combined effect of formation of strong metal‑nitrogen bonding, solid solution strengthening, the formation of the nanocomposite structure and ion beam assisted bombardment strengthening. Furthermore, the excellent corrosion resistance can be obtained by the (AlCrMoTiV)N x films. • AlCrMoTiV HEA nitride films were prepared by co-filter cathodic vacuum arc deposition. • Effect of gas flow ratio of N 2 :Ar on structure and properties of film was studied. • The phase structure changes from BCC to amorphous and then to nanocomposite structure. • (AlCrMoTiV)N x films prepared under N 2 :Ar = 7:4 show a high-hardness of 35.7 GPa. • AlCrMoTiV HEA nitride films show better corrosion resistance than 304 stainless steel. [ABSTRACT FROM AUTHOR]

• The intensive investigation and comparison of the degradation behavior and structural transformation of Mylar, Teonex, Vectra, Kapton and Teflon under AO exposure and Fe+-Ion irradiation in a space environment. • ReaxFF-MD simulations verify the essential interatomic interactions between AO/Fe+and the selected polymers and draw additional information. Polymers are ubiquitous in the aerospace industry, and their atomic oxygen (AO) exposure and ion irradiation stability are a chief concern. In this work, the AO and ion-irradiation degradation mechanisms for Mylar, Teonex, Vectra, Kapton and Teflon were investigated by adopting ground-based simulated environments (AO exposure and Fe+ irradiation tests) and reactive molecular dynamics (ReaxFF-MD) simulations. Mylar, Teonex, Vectra and Kapton show analogous AO degradation mechanisms, which are associated with the fracture and oxidation of the molecular chain skeleton and the emission of volatile small molecular species, resulting in mass loss. Teflon exhibits distinctive AO erosion kinetics, and the existence of an overall drift of the macromolecular chain with AO emission greatly compromises its stability. Moreover, Mylar, Teonex, Vectra and Kapton also exhibit comparable irradiation damage mechanisms and radical evolution. The elimination of C=O, C O-C and C N (only for Kapton) bonds and the generation of phenyl, phenoxyl and ketone radicals are the primary consequences of Fe+ irradiation. However, only subtle C-F bond breakage for Teflon can be detected during Fe+ irradiation, and the corresponding peroxide radicals are formed after contact with air atmosphere. [Display omitted] [ABSTRACT FROM AUTHOR]

The present study reports room temperature ferromagnetism observed in Co implanted, Er implanted and (Co, Er) co-implanted ZnO films deposited by filtered cathode vacuum arc (FCVA) on sapphire substrates. The microstructures, surface morphologies, electrical and magnetic properties of pure and implanted ZnO films were investigated. X-ray diffraction results confirm that the implantation of Co and Er ions cause the substitution of Zn ions without the formation of secondary phases. The results of X-ray photoelectron spectroscopy indicate that the Er ions and Co ions are in trivalent and divalent states, respectively. After ions implantation, the electrical properties of the films are improved and the carrier concentration of Er implanted ZnO film is higher than that of Co implanted ZnO film. Substantial intrinsic ferromagnetism has been observed for all the implanted ZnO films. The saturation magnetization for the Er implanted ZnO film is higher than that of the Co implanted ZnO film and the magnetization is further enhanced by (Co, Er) co-implanting. The carrier mediated exchange mechanism can well describe the origin of ferromagnetism in the doped ZnO films. Our results can provide a reference for preparing high-quality diluted magnetic semiconductors (DMSs) by RE elements and TM elements co-doping in ZnO films. [Display omitted] • A filtered cathode vacuum arc (FCVA) deposition system was used to grow ZnO films on sapphire substrates. • The saturation magnetization for the Er implanted ZnO film is higher than that of Co implanted ZnO. • The magnetization is enhanced by Co-Er co-doping compared with Co doped and Er doped film. • The magnetization shows carrier concentration-dependent behavior. [ABSTRACT FROM AUTHOR]

Metal bipolar plates (BPPs) are candidates with great promise to replace conventional carbon-based BPPs. However, the drawbacks caused by the corrosion and passivation of metal bipolar plates need to be addressed urgently. In present study, corrosion-resistant and interfacial conductive high-entropy alloy and ceramic coatings possess great potential in the application of surface modification of bipolar plates in proton exchange membrane fuel cells (PEMFCs). An original co-filtered cathodic vacuum arc deposition (C-FCVAD) is designed to prepare AlTiVCrMo high-entropy alloy (HEA) and (AlTiVCrMo)N x high-entropy ceramic (HEC) coatings with different nitrogen content, and their feasibility as surface modification methods of bipolar plates is investigated by analyzing the microstructure, corrosion properties, interfacial conductivity and hydrophobicity of the coatings. The obvious body-centered cubic (BCC) structure can be observed in HEA coating, and amorphous structure is gradually formed as the nitrogen content increases to 28.12 at. %. Finally, polycrystal structure is formed when nitrogen content reached the maximum. The electrochemical corrosion and interfacial contact resistance (ICR) results significantly demonstrate that the coatings have enhanced corrosion resistance and conductivity. The bipolar plates with AlTiVCrMo HEA and (AlTiVCrMo)N x HEC coatings as surface modification methods have good application potential in PEMFCs operating environment. • The novel idea of HEA and HEC coatings adopting for bipolar plates in PEMFCs. • Development of Co-filtered cathodic vacuum arc deposition technique for HEC coating. • The HEC coatings show excellent corrosion resistance and super-low ICRs. [ABSTRACT FROM AUTHOR]