Cr–Cu–N hard films were deposited on Si substrates using ion beam assisted magnetron sputtering (IBAMS). The effects of Cu content and ion beam bombardment energy on the microstructure and mechanical ...properties of the films were studied. The results show that Cu addition can restrict the growth of columnar grain to a certain degree. With increasing the ion assisting energy from 400eV to 800eV, a finer and denser grained Cr -Cu -N film can be formed. XRD and XPS analyses indicate that the films under lower assisting energy of 400eV are composed of Cr and CrN phases. However, only CrN phase appears under bombarding energy of 800eV. Cu mainly exists with a free state in the Cr–Cu–N films. Cu addition has no obvious impact on the film microhardness under the same ion assisting energy of 400eV. The fracture toughness of the films improves with increasing Cu content. Both the microhardness and fracture toughness of the films significantly increase when ion bombardment energy increases to 800eV. It is mainly attributed to the films densification by ion bombardment. The combining ion bombardment with Cu addition can further increase the film fracture toughness.
► Cr–Cu–N films were prepared using ion beam assisted magnetron sputtering. ► Cu addition shows little influence on film hardness at same ion assisting energy. ► The improvement of film hardness is mainly due to higher energy ion bombardment. ► Combining ion bombardment with Cu addition can increase film fracture toughness.
CrAlN coatings were deposited on silicon and AISI H13 steel substrates using a modified ion beam enhanced magnetron sputtering system. At the modified ion beam bombardment, the effects of bias ...voltage and Al/(Cr + Al) ratio on microstructure and mechanical properties of the coatings were studied. The X-ray diffraction data showed that all CrAlN coatings were crystallized in the cubic NaCl B1 structure, showing the (111), (200), and (220) preferential orientation. It is noted that the (111) diffraction peak intensity decreased and the peaks broadened as the bias voltage increased at the same ratio of Al/Cr targets power, which is attributed to the variation in the grain size and microstrain. The microstructure observation of the coatings by field emission scanning electron microscopy cross-section morphology shows that the columnar grain became more compact and dense with increasing substrate bias voltage and Al concentration. At a substrate bias voltage of −120 V and a Al/(Cr + Al) ratio of 40%, the coating had the highest hardness (33.8 GPa) and excellent adhesion to the substrate.
Sn
4+
-doped titanium dioxide photocatalytic films were synthesized on 304 stainless steel (SS) by a duplex treatment. The SS substrates were alloyed with titanium (Ti) through cathodic-arc ion ...plating followed by a microarc oxidation (MAO) treatment in different electrolytes. Field-emission scanning electron microscopy, x-ray diffraction, and energy dispersive spectroscopy were used to characterize the films surface morphology, crystalline phase, and composition, respectively. Photocatalytic activity was measured using an UV-Vis spectrophotometer. It was found that the films with a porous structure are mainly composed of TiO
2
, which exists in an anatase and rutile state. Furthermore, small quantities of SnO
2
have been found in the Sn
4+
-doped titanium dioxide films. The fraction of anatase varies with the MAO time and electrolytes, whereas the pore size remains the similar with the same MAO current intensity and density and the surface roughness increases slightly with increasing MAO time. It was also found that the photocatalytic activity of the Sn
4+
-doped porous film improved, and the film synthesized with a shorter MAO time in a lower Na
2
SnO
3
-containing electrolyte is superior to the films with longer MAO times and higher Na
2
SnO
3
concentrations.
ZrN/Zr-N/Zr coatings were deposited on H13 steel by close field unbalanced magnetron sputtering ion plating (CFUBMSIP) technique. The effect of two main parameters such as OEM and bias voltage for ...the CFUBMSIP process on the microstructure, mechanical properties and impact fatigue behavior of the coatings was investigated. The results indicate that with OEM increasing from 55% to 65% the surface particles size of the coatings increases while it remains almost similar when the bias voltage changes from 60 to 75 V. An aggregation of the particles occurs on the coatings surface with further increasing the OEM and bias voltage to 75% and 90 V, respectively. The coatings show a columnar grain structure and are mainly composed of two phases of ZrN and Zr. The coating hardness decreases with OEM value increasing and both the coating hardness and modulus go up with bias voltage. The coating deposited under OEM of 65% and bias voltage of 75 V shows the best impact fatigue property.
•The Cr–Y alloyed layers were prepared on Ti2AlNb alloy by a novel method called double-glow plasma alloying.•The alloyed layers included a deposited layer and a inter diffusion layer.•The isothermal ...oxidation behavior of alloyed layers was studied at 750, 800, and 850 °C.•The alloyed layers successfully improved the oxidation resistance of Ti2AlNb alloy.
A Cr-Y alloyed layer was synthesized on the surface of Ti2AlNb by double glow plasma surface alloying technique. The morphology, phase composition and oxidation behaviors at 750 °C, 800 °C, and 850 °C of Cr-Y alloyed layers were systematically investigated. The results illustrated that Cr-Y alloyed layer was approximately 10 μm thick, which the morphology of alloyed layer was uniform and compact, with a flat and uniform interface to the matrix. Oxidation kinetics for the Cr-Y alloyed layer approximately followed the parabolic law, with an oxidation weight gain significantly lower than that of Ti2AlNb. The predominant oxides of Cr-Y layer were CrNbO4, Cr2O3, and Y2O3, which effectively hindered oxygen diffusion into the substrate.
Cu modified layer was prepared on the surface of AISI304 stainless steel by plasma surface alloying technique. The effects of processing parameters on the thickness, surface topography, ...microstructure and chemical composition of Cu modified layer were characterized using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The experimental results show that the surface modified layer is a duplex layer (deposited + diffused layer) with thickness of about 26 μm under the optimum process parameters. The modified layer is mainly composed of a mixture of Cu and expanded austenite phase. The ball-on-disk results show that the modified layer possesses low friction coefficients (0.25) and excellent wear resistance (wear volume 0.005×10
9
μm
3
). The Cu modified layer is very effective in killing the bacteria S. aureus. Meanwhile, no viable S. aureus is found after 3 h (100% killed) by contact with the Cu alloyed surface.
Austenitic stainless steel has been researched as a promising candidate material for bipolar plates in proton exchange membrane fuel cells. However, its interfacial contact resistance (ICR) is about ...16 times higher that of the Department of Energy (DOE) target (10 mΩ cm2), which leads to undesirable fuel cell performance. In this work, a new hybrid plasma surface engineering process, based on active screen plasma co-alloying, has been developed to simultaneously alloy 316 austenitic stainless steel (316 SS) surfaces with both nitrogen and niobium. The results demonstrated that the layer structure of the modified surfaces can be tailored by adjusting the treatment conditions. All the plasma treated 316 SS samples exhibited significantly reduced ICR below the DOE target of 10 mΩ cm2. The corrosion resistance of the N/Nb co-alloyed 316 SS was much better than active screen plasma nitrided and marginally better than the untreated material.
•A new plasma surface process for alloying 316 SS with N and Nb has been developed.•The surface layer structure can be tailored by adjusting the treatment conditions.•The ICR value of 316 SS can be significantly reduced to below the DOE target.
Due to their good mechanical and corrosion properties, relatively low cost and ease of manufacture, 316 austenitic stainless steel has been researched as a promising candidate material for bipolar ...plates in proton exchange membrane fuel cells. However, its interfacial contact resistance (ICR) is about 16 times higher than that of the Department of Energy target (10mΩcm2), which leads to undesirable fuel cell performance. In this work, active screen plasma (ASP) surface co-alloying treatments with both nitrogen and silver were developed to modify the surface of 316 stainless steel to reduce its ICR required for high-performance bipolar plates. The treated surfaces were fully studied by means of scanning electron microscopy, X-ray diffraction, glow discharge optical emission spectroscopy and energy dispersive spectroscopy. The experimental results demonstrated that a duplex surface layer structure consisting of an Ag-rich surface deposition layer supported by an S-phase case was generated by the ASP surface co-alloying treatment. The ASP co-alloying treated surfaces showed increased corrosion potential and reduced corrosion current density, and significantly improved surface electrical conductivity. This could be attributed to the introduction of metallic Ag particles by this novel surface plasma treatment.
•Radically reduced interfacial contact resistance of 316 by surface N/Ag co-alloying•A duplex surface layer structure produced by one-step plasma surface treatment
Mo surface-modified layer in Ti6Al4V alloy was prepared using plasma surface alloying technique. Microstructure of the modified layer was analyzed using X-ray photoelectron spectroscopy (XPS), ...rough-meter and GDA750 glow discharge optical emission spectrometer. Phase composition of the Mo surface-modified layer was characterized by D/max 2500 X-ray diffraction. Results show that the Mo surface-modified layers consist of pure Mo surface layer with 1 1 0 and 2 1 1 orientations and diffusion layer. Mo 3d, O 1s, C 1s and Ti 2p, O 1s, C 1s XPS spectra are recorded at topsurface in the Mo-modified layer and titanium substrate respectively. Because of the different roughness and microstructure, the Mo surface-modified layer can to some extent inhibit bacteria adherence.
Cr–N coatings were deposited using the ion-beam-assisted magnetron sputtering technique. The microstructure and mechanical properties of Cr–N coatings were found to be dependent on the ion ...bombardment energy. The microstructure of the coatings changes from columnar structure to fine and dense grains when the ion bombardment energy increases from 0 to 800
eV and to equiaxial grains for an ion energy of 1200
eV. The coatings average grain size, which is determined by the Voigt profile function, decreases from 20.3
nm at an ion energy of 0
eV to 8.8
nm at 800
eV and further increases to 21.5
nm at 1200
eV. Both the hardness and fracture toughness of the coatings are improved when the ion energy increases from 0 to 800
eV, which is related to the decrease of grain size. The grain size of the coating grown at an energy of 1200
eV is close to that of 0
eV, but the hardness and fracture toughness at 1200
eV are higher. This suggests that the improvement of hardness and fracture toughness is also related to the increased densification of the coatings caused by ion bombardment.
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