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Three different coatings, namely TiAlN, TiAlN (external)/NbN (internal) and NbN (external)/TiAlN (internal), were deposited on cemented carbides by arc ion plating. The comparative investigation conducted in this study elucidates the effect of the NbN layer and coating systems on the growth, mechanical properties, and tribological performance of the coatings. The results showed that the surface of the TiAlN and TiAlN/NbN coatings was smoother when TiAlN served as the external layer. The NbN/TiAlN coating, wherein NbN formed the external layer, had a much rougher but more symmetrical surface. With the introduction of the NbN layer, the increased micro stress induced a lower adhesion strength in the TiAlN/NbN and NbN/TiAlN coatings. The TiAlN/NbN and NbN/TiAlN coatings exhibited higher hardness and hardness/effective elastic modulus (H/E*). During the friction test, when the temperature was elevated to 700 °C, the tribological performance of the monolayer TiAlN coating was the lowest because of the TiO2-induced breakage of the dense tribo-oxide film. The NbN layer participated in the formation of a NbOx film at elevated temperatures, which was responsible for the high tribological performance of the two bilayer coatings. When the NbN layer was on the outermost layer and in direct contact with the elevated temperature atmosphere, the NbN/TiAlN coating generated a tribo-oxide film with high integrity, and its coefficient of friction decreased by 27% of that at room temperature. Therefore, the NbN/TiAlN coating exhibited the highest wear resistance at 700 °C.

A multilayer coating comprising Cr as IR reflector, alternative AlCrN/AlCrON as absorber and AlCrO as anti-reflective layer has been designed and deposited on stainless-steel substrate by cathodic arc ion plating. It was found that the selectivity (α/e) of multilayer coating was increased from 0.919/0.128 to 0.928/0.105 after annealing at 550 °C in vacuum for 2000 h. Microstructural analysis revealed the formation of nanocrystalline/amorphous composite structures in the AlCrN/AlCrON absorbers and AlCrO anti-reflective layer, which was beneficial to improve the thermal tolerance of the multilayer coating by restraining nanoparticles agglomeration and interface degradation. The enhancement in selectivity after vacuum annealing was ascribed to the partial recrystallization of the amorphous matrices, resulting in the formation of nitride nanoparticles, which can promote the intrinsic absorption due to the increase of optical path. However, the multilayer coating destabilized when annealed at 550 °C in air for 2000 h. Based on the microstructural characterization, the corresponding failure mechanism was attributed to the element migration between adjacent sublayers, structural relaxation of the amorphous matrix, and surface solute atoms segregation induced oxidation and coalescence of nanoparticles, which degenerated the intrinsic absorption and localized surface plasmon resonance of nanoparticles in AlCrN and AlCrON absorbers.

Hard nitride coatings have the prospect of acting as protective layers for cutting tools because of their excellent mechanical properties and wear resistance. To enhance the mechanical, tribological, and high-temperature oxidation properties, the structural design of the coating is important. In this study, TiSiN, CrAlN/TiSiN bilayer and CrAlN/TiSiN multilayer coatings were deposited on the surface of high-speed steel by multi-arc ion plating technology. The microstructure, phase composition, mechanical properties and high-temperature tribological properties of prepared coatings were analyzed. Results indicated that the TiSiN and CrAlN/TiSiN bilayer coatings contain TiN phases and the CrAlN/TiSiN multilayer coating contains three main phases of TiN, AlN and CrN. The CrAlN/TiSiN multilayer coating possesses a denser microstructure than the other two coatings. The multilayer structure improves the cohesive and bonding strength of the coating by reducing the shear stress. The CrAlN/TiSiN multilayer coating exhibits a stable coefficient of friction and excellent wear resistance during high-temperature friction. The formation of TiO2 and Al2O3 oxide layers on the surface of the coating in a high-temperature environment contributes to the desired tribological properties of the coatings.

High entropy ceramics (HECs) films (TiCrZrVAl)N were deposited on Inconel 718 alloys by multi-arc ion plating (MAIP) equipment at different nitrogen flow ratios Rn N2/(N2+ Ar). The effects of Rn (0%, 20%, 50%, 80%, 90%) on the evolution of microstructure, mechanical properties, and tribological properties of films were systematically studied. The films deposited at low Rn exhibited an amorphous structure and smooth cross-section, whereas the films at Rn of 50% and higher showed a face-centered-cubic (FCC) NaCl-type structure with loose columnar cross-section. With the increase of Rn, the content of the N element increased, the Cr element decreased, and other elements (Ti, Zr, V, Al) nearly remained stable. The films' hardness and elastic modulus increased gradually and reached the maximum value of 31.08 ± 1.81 GPa and 387.66 ± 12.49 GPa, respectively, when Rn was 80%. The films deposited at Rn of 20% invalided easily in tribology tests, whereas the films prepared under Rn exceeded 20% presented outstanding wear resistance and obtained the minimum wear rate of 7.4×10-16 m3/(N·m) when Rn is 80%.

As patients are dissatisfied with the excessive weight of Co-based knee femoral components, it is an urgent need to reduce their weight without compromising the excellent mechanical properties. In the present study, femoral components of knee with Ti6Al4V alloy (86 g) or Co–Cr alloy (192 g) were printed by selective laser melting (SLM). In order to improve the mechanical properties and biocompatibility of 3D-printed Ti6Al4V, TiN and TiCrN coating layers were deposited on the surface of SLM Ti6Al4V using arc ion plating (AIP) system. The surface characterizations were analyzed by scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS), X-ray diffraction (XRD), contact angle tensiometer, and contact profilometer. The wear property, hardness value and corrosion resistance in phosphate buffered saline (PBS) were also investigated through vickers hardness, sliding wear test, electrochemical impedance spectroscopy and potentiodynamic polarization. The antibacterial capability and biocompatibility were assessed with Staphylococcus aureus and mesenchymal stem cells (MSCs) in vitro. Results illustrated that, after coating SLM Ti6Al4V with thin TiN and TiCrN layers, the hardness, anti-wear performance and corrosion resistance of SLM Ti6Al4V were significantly improved and became comparable to SLM CoCr. The TiN and TiCrN coated SLM Ti6Al4V also showed moderate antibacterial ability, and excellent biocompatibility in comparation with SLM Ti6Al4V and SLM CoCr.

The influence of bias voltage on surface microstructure of TiN films deposited on Ti substrate by multi-arc ion plating was systematically investigated. The TiN films were characterized using X-ray diffraction, scanning electron microscopy and atomic force microscopy. The corrosion resistance was tested by potentiodynamic polarization and electrochemical impedance spectroscopy at 70–80 °C in the simulated PEMFC cathode environment. The results show that the surface microstructure of TiN film depends strongly on the bias voltages. At the bias voltage of −100 V, TiN film shows the optimum surface microstructure with the lowest surface roughness Rz of 0.039 μm tested by AFM and relatively high compactness. The optimized TiN film exhibits excellent corrosion resistance with corrosion current density of 0.87 μA/cm2 in a 0.5 M H2SO4 + 2 ppm HF solution at 80 °C with air and a low interfacial contact resistance (ICR) value of 3.0 mΩ cm2 at a compaction force of 140 N/cm2. These results support TiN as a promising coating material for Ti bipolar plates.

To develop an ultra-high-temperature resistant coating for a reusable thermal protection system, the preparation of a tantalum-based MoSi2-Mo coating by a new two-step process of multi-arc ion plating and halide activated pack cementation is presented. The coating has a dense structure and is well compatible with the tantalum substrate, which can be thermally shocked from room temperature to 1750 °C for 360 cycles without failure. The mechanism of the coating’s excellent resistance to high-temperature thermal shocks is that a strong-binding gradient interface and a dense SiO2 oxide scale with good oxygen resistance are formed by the high-temperature self-diffusion of Si.

Nitride coatings have been generally applied on light alloys like titanium and aluminium to promote their multiple performances, including hardness, thermal stability and wear resistance. In this work, TiAlSiN/TiN multilayered (ML) coating and TiAlSiN single-layer (SL) coating were deposited on TC18 (Ti5Al5Mo5V1CrFe) alloy by Multi-arc ion plating technique. The microstructure and chemical composition of the coatings were evaluated by SEM, XRD and XPS. Additionally, hardness, adhesion and wear resistance were measured through nanoindentation, scratch spectrometer and ball-on-disk tribometer. The results present that both ML and SL coating contain three main phases of TiN, Al2O3 and Si3N4. Nevertheless, the adhesion of ML coating is 62.4 N, compared to that of the SL coating is 51.8 N. The parameter H3/E2 as an indication of plastic deformation to evaluate wear resistance shows that the ML coating has high hardness and high toughness concurrently. The tribological study indicated that the wear rate of the ML coated specimen was 1/7 of the SL coated counterpart.

NiCrAlY coatings are widely applied on various alloy components to enhance oxidation and/or corrosion resistance at high temperatures. However, elements interdiffusion occurs between them due to composition difference. Although various diffusion barriers (DBs) are reported, this problem is still far from completely solved as most ceramic barriers suffer from poor adherence, while the metallic barriers play a limited role. In this study, NiCrAlY coating was deposited onto a second-generation single-crystal superalloy by arc ion plating. A novel simple method is provided to address elements interdiffusion. By pre-oxidation at a moderate temperature, a thin scale of Ni(Co)O forms at the alloy surface. It transforms to be an alumina/NiCoCr alloy/alumina sandwich by an in-situ reaction with the overlaying NiCrAlY coating and the alloy substrate at high service temperatures, which offers good barrier ability in conjunction with strong adhesion. In the presence of such an alumina/alloy/alumina DB, the NiCrAlY coating provides high resistance to oxidation and scale spallation for the alloy substrate.

In this paper, TiN, TiN-Ag and TiN-Cu coatings were prepared by multi-arc ion plating. TiO2 nanotube arrays were constructed on the coatings by anodization reaction at room temperature. Building TiO2 nanotube arrays on the coating can retain the performance of the hard coating itself and reduce the process of destroying the structure of the TiO2 nanotubes. Non-metallic N doping and co-doping of metallic Ag, Cu and non-metallic N make the nanotubes catalyzed by visible light. The specific surface area of TiO2 by changed the anodizing voltage. The results show that the anodic oxidation voltage is 15V and Cu, N co-doped TiO2 photocatalytic degradation performance is the best.

In this work, the Metal-rich phase Chromium Aluminum (CrAl)/Ceramic phase Chromium Aluminum Nitride (CrAlN) multi-layer coatings were prepared by Arc Ion Plating (AIP). The micro-structure and phase composition of CrAl/CrAlN multi-layer coatings were characterized, and the microstructure, mechanical properties, residual stress and fracture toughness of the coating were emphatically analyzed. It has been found out that the residual stress of the multi-layer coating was only −0.932 ± 0.065 GPa, which was significantly lower than that of the mono-layer coating for −1.569 ± 0.093 GPa. At the same time, it was also found that the preferred growth orientation of the coating changed from a mono-layer (111) to a multi-layer (200) crystal plane. The hardness of the multi-layer (22.74 ± 0.57 GPa) is slightly lower than that of the mono-layer (24.92 ± 0.5 GPa), and the adhesion strength (46.2 ± 3.8 N) is obviously higher than that of the mono-layer (37.4 ± 2.4 N), and the fracture toughness is also higher (8.7 ± 0.8 MPa m1/2). In addition, the mechanism of crack initiation and propagation in stress-induced coatings was studied in detail on the basis of the structure of micro-nano CrAl/CrAlN multi-layer coatings.

The two-layer and multi-layer Cr/CrxN coatings were fabricated on 316 L stainless steel (316 L SS) substrates by the arc ion plating technique. The two-layer Cr/CrxN coating was a typical CrN coating with an adhesive Cr layer. And the multi-layer Cr/CrxN coating design was in two dimensions. In the first dimension, the multi-layer Cr/CrxN coating consisted of alternative Cr/CrN layers with the thickness ratio of 1:5; in the second dimension, the alternative Cr2N layers with the thickness of 10 nm were inserted in CrN layers. This design was expected to increase transverse interfaces in a smaller scale. The microstructures, mechanical, corrosion and tribocorrosion performances of both Cr/CrxN coatings were systematically investigated. The results showed that the special multi-layer design of Cr/CrxN coatings improved mechanical, anti-corrosion and anti-tribocorrosion performances. Compared with the two-layer Cr/CrxN coating, the reduced tribocorrosion damage of the muti-layer Cr/CrxN coating was closely related to the inhibited synergistic effect between electrochemical corrosion and mechanical wear. In conclusion, the multi-layer Cr/CrxN coating was more suitable to work as the surface protective coating than the two-layer Cr/CrxN coating in seawater.

AlCrON coatings were deposited on plasma nitrided steel substrates by multi-arc ion plating under different oxygen flow rates. The surface morphology, structure, composition, mechanical properties, and tribological behavior were investigated systematically. The coating surface roughness increases with increasing oxygen flow rate. The structural analysis show as-deposited coatings exhibit B1 NaCl like solid solution phases, transformed from fcc-(Cr, Al)N to fcc-(Cr, Al)ON followed by fcc-(Cr, Al)2O3 phase structure for coating deposited at the oxygen flow rate of 300 sccm. The hardness and elastic modulus of the coating decrease with increasing oxygen content due to phase transformation. The minimum friction coefficient of 0.52 and the lowest wear rate of 1.57 × 10−16 m3/(N∙m) at 600 °C are obtained for the coating deposited at 150 sccm, which is attributed to the excellent adhesion and thermal stability.

AISI 316L steel is often used in materials applied toward nuclear power but are subjected to pitting corrosion in a marine environment. In this study, (Cr, W, Al, Ti, Si)N multilayer coatings were deposited using multi-arc ion plating on the surface of non-nitrided and nitrided AISI 316L steel. The microstructure and corrosion resistance of four different systems were investigated, namely, (i) untreated AISI 316L steel, (ii) plasma nitrided (PN), (iii) coated on an untreated matrix (coating) only, and (iv) coated on nitrided (hybrid) specimens. The phase structures, morphologies, and compositions of the different specimens were characterized using X-ray diffraction, transmission electron microscope, Atomic Force Microscope, scanning electron microscope, X-ray photoelectron spectroscopy, and energy dispersive x-ray spectroscopy. The results show that a thin CrWAlTiSiN multilayer coating, approximately 2.3 μm in thickness, is deposited on the surface of an ~12 μm nitrided layer. Potentio-dynamic polarization and electrochemical impedance spectroscopy were used to evaluate the assessment of the electrochemical behavior in the natural seawater of China's Yellow Sea. The hybrid specimens exhibited excellent corrosion resistance compared to both the nitrided and coated specimens.

The NiCrAlTi coatings free of N and with N incorporations were deposited on austenitic stainless steel 304L by magnetron sputtering in Ar and in gas mixture of Ar and N2, respectively. The N incorporated in the coatings existed as nitride precipitates (from ∼3 vol.% to ∼17 vol.%) after vacuum annealing. All the NiCrAlTi coatings, whatever free of N or with N incorporations, exhibited better resistance against cavitation erosion than ion plating TiN coating and the substrate 304 L in ultrasonic cavitation tests. The NiCrAlTi coating free of N incorporation presents superior cavitation erosion resistance. However, the nitrogen incorporation within the NiCrAlTi coatings showed negative effects on the resistance against cavitation erosion.

Thick Ti/TiN multilayer coatings with different thicknesses of Ti sublayers were prepared on Ti–6Al–4V titanium alloy by arc ion plating technology. The corrosion resistance of coatings was investigated under solid NaCl, water vapor and oxygen at 450 oC. The results demonstrate that the as-prepared Ti/TiN multilayer coatings were consisted of Ti, Ti2N and TiN phases. The crystalline grains of TiN layers exhibited columnar growth, while Ti sublayers with equiaxed grains interrupted the continuity of columnar grains of TiN layers in Ti/TiN multilayer coatings. With the increasing in Ti layer thickness, more and larger macroparticles were embedded into the multilayer coatings. Ti/TiN multilayer coating with thinner Ti sublayer maintained integrity except for the formation of a continuous thin corrosion scale after corrosion tests and no obvious internal oxidation occurred, presenting favorable corrosion resistance. In contrast, locally severe internal oxidation occurred to Ti/TiN multilayer coatings with thicker Ti layer, deteriorating the corrosion resistance of multilayer coatings. Oxygen inwardly diffused from ambient environment to sublayers along the pinholes or columnar structure penetrating through TiN layer. This resulted in internal oxidation accompanied with volume expansion, then bending and cracking of sublayers, and finally promoting localized corrosion of multilayer coatings with thicker Ti sublayer. Besides, the existence of large macroparticles facilitated this localized internal oxidation. Internal oxide also occurred at the edge of TiN single layer coating, which was essentially detrimental for coating protection with prolonged exposure.

Tantalum (Ta) alloys are important ultra-high-temperature structural materials owing to their excellent high-temperature mechanical properties and processability. However, they exhibit poor high-temperature oxidation resistance. In this study, a dense MoSi2 ceramic coating was prepared on a Ta substrate using an innovative multi-arc ion plating process and halide activated pack cementation in order to improve its ultra-high-temperature oxidation resistance. This ceramic coating exhibited a low roughness space arithmetic (287.1 ± 26.3 nm) and a dense structure. The relationship between the thickness of the coating and the duration of pack-cementation at 1250 ℃ was parabolic. The coating had a service life of more than 12 h at 1750 ℃, and showed excellent high-temperature oxidation resistance because of the uniform and dense structure of the coating and the rapid formation of a dense SiO2 layer with low O2 permeability during high-temperature oxidation.

The preparation, microstructure and mechanical properties of ZTA particles reinforced Fe matrix composites (ZTAP/Fe composites) were systematically investigated. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) were used to analyze the microstructure and phase constituents, the hardness (H), Young's modulus (E) and plasticity factor (δA) were determined as well. The nickel-chromium double-layer coated ZTAP of core-shell structure was prepared by electroless plating and multi-arc ion plating technologies. The modified ZTAP is consisted of the α-Al2O3, t-ZrO2, α-Cr and γ-Ni phases. In addition, the compressive strength of ceramic preforms is high due to a compact sintering neck formed among ZTAP during high temperature sintering. The preferred sintering process for ZTA ceramic preforms is determined as 1350 °C + 1 h, in this case the preforms show the remarkable porosity and highest compressive strength which are 27.8% and 35.0 MPa, respectively. The interfacial metallurgical chemical reactions occurred during infiltration casting process, which ensure the excellent metallurgical interfacial bonding of the ZTAP/Fe composites. The interface contains double transition layers, which refer to silicate and CrFe phases, respectively. The H, E and δA of interfacial double transition layers were measured by the nano-indentation method, the values of which are situated between the ZTAP and iron matrix.

In physical vapor deposition (PVD), the energy and incident angle of ions can be adjusted easily by applying an electromagnetic field so that coatings with different structures and properties can be produced. In this work, several high-ionization coating techniques are employed to deposit TiAlN coatings to compare the effectiveness of each technique and resulting coating properties. The continuous high-power magnetron sputtering (C-HPMS) technique shows advantages in the deposition rate and coating performance. In addition, a deposition rate of 400 nm/min is achieved by C-HPMS, whereas those of high power impulse magnetron sputtering (HiPIMS) and arc ion plating (AIP) are 85 nm/min and 225 nm/min, respectively. The coating also shows a particle-free and dense morphology with a smaller surface roughness of 22.4 nm. Owing to efficient ionization, the TiAlN coating deposited by C-HPMS has a high hardness of 33.2 GPa which is comparable to those prepared by AIP and HiPIMS but with small residual stress. The results provide valuable information on how to choose the proper techniques and parameters to produce coatings with the desirable adhesion strength, tribological properties, as well as corrosion resistance.

Coating of zirconium-based substrates is a promising method to obtain accident-tolerant fuel claddings for light water reactors. In this study, CrSi-based coatings with varying Si content were deposited by multi-arc ion plating, and the effect of Si content on the oxidation behavior of the coatings in air at various temperatures (maximum 1160 °C) was investigated. The solid solution phase, formed by Si in CrSi coating, was seen to improve the oxidation performance of Cr. The nanocomposite structure in CrSiN coating can further improve the oxidation and stability of CrN. The results indicated that Si in CrSi-based coatings plays an effective role in the oxidation resistance of Zircaloy at high temperatures. Thus, these coatings could be used as potential accident tolerant fuel cladding materials for light water reactor applications.

MCrAlY (M=Ni and/or Co) overlay coating is widely used as a protective coating against high temperature oxidation and corrosion. However, due to its big difference in chemical composition with the underlying superalloy, elements interdiffusion occurs inevitably. One of the direct results is the formation of interdiffusion zone (IDZ) and secondary reaction zone (SRZ) with a high density of fine topological closed-packed phases (TCPs), weakening dramatically the mechanical properties of the alloy substrate. It is by now the main problem of modern high-temperature metallic coatings, but there are still hardly any reports studying the formation, growth and transformation of IDZ and SRZ in deep, as well as the precipitation of TCPs. In this work, a typical NiCrAlY coating is deposited by arc ion plating on a single-crystal superalloy N5. Elements interdiffusion between them and its relationship on microstructure were clarified. Cr rather than Al from the coating diffuses into the alloy at high temperatures and segregates immediately beneath their interface, contributing largely to the formation of IDZ. Simultaneously, diffusion of Ni from the deep alloy to IDZ leads to the formation and continuous expansion of SRZ.

Through multi-arc ion plating technology, the VCN coatings were successfully prepared under various bias voltages. The microstructure, mechanical property, anti-corrosion capability and tribological performance of these VCN coatings were comparatively studied. With the bias voltage increased from −25 to −100 V, the adhesion force and hardness of VCN coatings increased by 73.33% (22.5 to 39 N) and 14.83% (31.7 to 36.4 GPa). Besides, the toughness, corrosion resistance and anti-wear ability of VCN coatings were enhanced to varying degrees by changing the bias voltage. By contrast, the VCN coating at −100 V presented the smallest friction coefficient (COF) of 0.113 and wear rate of 5.25 × 10−7 mm3/Nm, implying an attractive protective effect for key friction parts in marine environment.

The V–C–N coatings with various carbon contents were prepared by multi-arc ion plating method on 304 stainless steel and Si (100) substrates. The effects of carbon content on microstructure, mechanical behavior, tribological behavior and corrosion behavior of V–C–N coating were systematically evaluated. Results showed that the VC phase and amorphous phase were formed after the addition of carbon into VN coating. In the meantime, the critical load and hardness of V–C–N coating increased to 40 N and 36.5 GPa when the carbon content increased to 14.73 at%, respectively. Moreover, the incorporation of carbon could enhance the toughness, corrosion resistance and wear resistance of VN coating. By comparison, the V–C–N coating with 14.73 at.% C showed the lowest friction coefficient (COF = 0.12) and wear rate (7.2 × 10−7 mm3/Nm), implying a great potential for the protection of mechanical component in marine environment.

The mechanical and tribological characteristics of the VN/AlCrN multilayered coating films are investigated for cutting tools by using the arc ion plating (AIP) method with a rectilinear magnetic filtering system. The VN coating film forms vanadium oxide VxO1–x that has low friction coefficient on a surface above 500°C, whereas AlCrN coatings exhibit higher hot hardness and oxidation resistance. Therefore, the VN/AlCrN multilayer coatings are expected to demonstrate both superior lubricity and heat resistance, whose characteristics depend mostly on the combination of VN and AlCrN films. Moreover, some lower cutting force, tool wear, and tool flank temperature are obtained at high speed end milling of a prehardened stainless steel, as expected.

To improve both the critical scratch load and micro-hardness of (Al, Cr) N coating film, (Al, Cr, W)-based coating film was developed. In this study, to clarify the tool wear of the (Al,Cr,W)-based coated tool in the cutting of alloy steel AISI 5120H, the wear progress and wear mechanism of the coating film in the cutting of alloy steel AISI 5120H using six types of (Al,Cr,W)-based coated tools were investigated. The cutting conditions were a cutting speed of 5.00 m/s, feed rate of 0.25 mm/rev and cutting depth of 0.1 mm. The following results were obtained: 1) The wear progress of the (Al64,Cr28,W8)N-coated tool was slower than that of the (Al60,Cr25,W15)N-coated tool. 2) When a (Al64,Cr28,W8)-target was used to deposit a cemented carbide with a bias voltage of -150 V, the wear progress of the (Al64,Cr28,W8)N coated tool was slightly slower than that of the (Al64,Cr28,W8)(C,N)- or the (Al64,Cr28,W8)C-coated tool. 3) The wear progress of the (Al64,Cr28,W8)N coated tool with a bias voltage of -80 V was the slowest.

Cr coatings were deposited by multi-arc ion plating under different gas pressures and bias potentials, and the oxidation behaviors of the coatings in air at various temperatures (max = 1060 °C) were investigated. The Cr coating structure could be modulated by varying the gas pressure and the bias potential, which affected its oxidation performance. The relationship among the gas pressure, the bias potential, and the oxidation performance was nonmonotonic. The formation of Cr2O3 caused a reduction in the oxidation weight gain of Zircaloy by 93.35%, indicating that our Cr coating played an effective role in the protection of Zircaloy at high temperatures.

The TiSiN coating was prepared by arc ion plating to improve wear resistance of titanium alloy at elevated temperatures. The thickness of 1.97 μm and the columnar crystal were observed in cross section image. It was found that the TiSiN coating had a lower friction coefficient at high temperatures than at room temperature. Nevertheless, the rising wear rate at the temperature of 500 °C indicated the destruction of the coating. The friction process would destroy the columnar crystal and generate oxide, amorphous phase and a lot of nanocrystalline with defects. Meanwhile, an amount of cracks were found in the coating at 500 °C which allowed oxygen get in touch with the interior of the coating and resulted in a more serious oxidization.

For enhancing accident tolerance in current operating LWRs, Zr-based claddings with a protective layer, which have outstanding resistance to high-temperature oxidation, are selected as strong candidates for accident-tolerant fuel claddings. One of the key factors determining the successful application of these coated claddings is their ability to maintain their coating layer during normal operation without significant damage. This study aimed to verify the scratch and fretting wear behaviors of coated Zircaloy-4 claddings deposited with a Cr–10Al binary alloy target (CrAl) by the arc ion plating method. In the scratch tests, the commercial Zircaloy-4 samples showed accumulated scratch grooves with ductile chipping caused by adhesive failure. However, there was no gross spallation, except for well-developed scratch traces caused by plastic deformation, on the entire stroke length of the CrAl-coated Zircaloy-4. The wear resistance of the CrAl-coated Zircaloy-4 against the as-received Zr grid was improved significantly because of its high load support capability owing to the coating layer and the formation of a load-bearing layer by the material transfer when compared with the results of the uncoated Zircaloy-4. Furthermore, when the Zr grid was pre-oxidized, the wear amount of the CrAl-coated Zircaloy-4 became negligible owing to the formation of a glaze layer by the interaction with the surface oxide of the Zr grid. According to the results of the high-temperature steam oxidation tests, the defected region of the CrAl coating layer caused by the scratch and fretting wear showed no further significant damage and still acted as a protective layer for enhancing the accident tolerance of the fuel cladding.

A serious of CrN/AlTiN nanolaminate films with different deposition temperatures were synthesized by Multi-Arc-Ion Plating (MAIP). The composition and microstructural evolution, hydrophobicity, and mechanical properties of CrN/AlTiN nanolaminate films were studied. It was found that these films were structured by FCC metal nitride phases and the preferred orientation changed form (111) to (200) with the deposition temperature increased to 450 °C. The SEM and TEM results showed that the rate of deposition as well as modulation period increased as the deposition temperature increased. On the contrary, the amount of macroparticles on the film's surface and the Cr content [Cr/(Cr + Ti + Al) ratio] decreased as the temperature increased. Among these films, CrN/AlTiN nanolaminate films deposited at 450 °C exhibited the highest hardness (∼37 GPa), lowest coefficient of friction (0.17). The contact angle (CA) results showed that the CrN/AlTiN nanolaminate composites films were hydrophobic and could be superhydrophobic after modification, which provided a new insight to prepare robust superhydrophobic films.

The TiSiN/Cu nano-multilayer coatings were deposited on Ti6Al4V substrate by multi-arc ion plating. The distribution and diffusion of Cu were controlled by the designed thickness of Cu layer and TiSiN barrier layer. Anti-bacterial behaviors and anti-fouling properties of TiSiN/Cu multilayer coatings were investigated. The TiSiN/Cu multilayer coating consists of nano-crystalline TiN and amorphous Si3N4. The metallic copper presents as nanosize clusters. When the copper layer thickness is 97.10 nm, the TiSiN/Cu coating with the maximum hardness 40.39 ± 0.77 GPa has the best antifouling behavior with the reduction rate of 79.36%, 66.21% and 41.37% for the P. triceratium, N. closterium and chlorella, respectively. Meanwhile, the TiSiN/Cu multilayer coatings have an excellent anti-bacterial behavior against Escherichia coli and Bacillus sp.

TiAlN/W2N multilayer coatings with various modulation periods from 140 to 680 nm were deposited on AISI 304 L SS by multi-arc ion plating and DC magnetron sputtering. The phase structures and chemical compositions of the as-prepared TiAlN/W2N multilayer coatings were investigated by a grazing incidence X-ray diffraction (GIXRD) and an energy dispersive spectrometer (EDS), respectively. The cross-sectional morphology, adhesion strength, hardness, and friction and wear behavior of the resulting TiAlN/W2N multilayer coatings were evaluated in detail. The results show that the as-prepared TiAlN/W2N coatings with different modulation periods are featured with a face-centered cubic (fcc) structure and have a dense and compact multilayer structure. The adhesion strengths of the TiAlN/W2N multilayer coating decrease gradually with the decreasing of the modulation periods from 680 to 140 nm, which results from more residual stress accumulated with the increasing numbers of the coating layers. The multilayered coating with the modulation period of 373 nm exhibits the maximum hardness of 1757 kgf·mm−2 and the lowest wear rate of 2.52 × 10−6 mm3(Nm)−1 among all samples. In addition, the TiAlN/W2N multilayer coating presents better tribological properties under high temperature than under room temperature due to a large number of oxide mixture (WO3, Al2O3, TiO2) produced on the wear surface during the rubbing process. The produced WO3 has a self-lubrication effect because of its special layered structure and high ionic potential, and other dense oxide mixture can prevent further oxidation of the multilayered coating.

Wear as a tribological process has a major influence on the reliability and life of journal bearings. The influences of Sn element doping on the microstructure and tribological properties of AlSn coatings on the surface of journal-bearing alloy were investigated by magnetron sputtering. AlSn coatings exhibit equiaxed crystals. Phase compositions transform from crystalline to amorphous as grain sizes gradually decreases with increased Sn target current. Sn mainly exists as a simple substance composed of Sn Sn bonds, reducing the friction coefficient of AlSn coatings sliding against a GCr15 steel ball. The hardness is 40 HV0.025, and the lowest friction coefficient of AlSn coatings was 0.15 when ISn is 0.25A. Overall, the AlSn coatings have excellent microstructure and tribological properties.

Monolayer MoNx and nano-multilayer CrN/Mo2N coatings were prepared by arc ion plating and characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM), friction tester and hardness tester. The results from TEM and XRD analysis showed that the crystal structure of MoNx and CrN/Mo2N coatings has a cubic lattice structure. The microhardness of MoNx coatings deposited at lower N2 pressure is about 2100 HV which is higher than 1950 HV of the coatings deposited at higher N2 pressure. The variation of friction coefficient of MoNx coatings influenced by N2 pressure is obvious at higher N2 pressure. The modulation period of CrN/Mo2N coatings is from 58.5 nm to 11.17 nm with increasing substrate rotation speed (Srs) in the range of 1–5 rpm. The maximum hardness of CrN/Mo2N nanomultilayer coatings, when the Srs is 7 rpm, is approximately 2950 HV. The value is 1.5 times higher than those of the MoNx monolayer coating (2000 HV). These enhancement effects in superlattice films could be attributed to the resistance to dislocation glide across interface between the MoN and CrN layers. The value of average friction coefficient of CrN/Mo2N nanomultilayer coatings is about 0.33 which is higher than 0.3 of MoNx coatings and lower than 0.6 of CrN. The wear rate of CrN/Mo2N nanomultilayer coatings is about 7 × 10−7 mm3/N·m which is obviously lower than 3.3 × 10−6 mm3/N·m of CrN coatings and higher than 1.2 × 10−7 mm3/N·m of MoNx coatings.

The high potential on the cathode side originated from the start-up/shut-down processes is the one that cannot be ignored, which will accelerate degradation of the bipolar plates and increase the interfacial contact resistance (ICR) eventually degrade the performance of PEMFCs. Therefore, the coating with corrosion resistance and conductivity is in urgent need of development. CrMoN coating is deposited on SS316L by closed field unbalanced magnetron sputter ion plating (CFUMSIP) with an aim to improve corrosion resistance and conductivity of SS316L under PEMFCs at shut-up/shut-down stages. In terms of high potential polarization test, the corrosion current density and ICR values are found to increase as the applied potential increases. The electrochemical degradation of CrMoN coated SS316L is investigated by electrochemical impedance spectroscopy (EIS). After 40 days of immersion, the charge transfer resistance (R ct ) of the CrMoN-4A coated SS316L is approximately 14 times greater than that of the uncoated SS316L and the ICR values are 11.2 mΩ cm 2 , indicating that the CrMoN-4A coating still has high corrosion resistance and well conductivity after long time immersion.

To meet the performance requirements in harsh marine service environment, developing coatings with excellent trbibocorrosion performance is necessary. Herein, TiSiCN/nitride duplex treatment coatings are prepared by gas nitriding and multi-arc ion plating in turn in this work. The hardness and density are enhanced by nitriding treatment. Duplex treatment coatings exhibit more excellent mechanical properties possessing the maximum hardness values (33 GPa) and exceptional load bearing capacity (88 N) compared to TiSiCN coating. Meanwhile, the effect of wear on corrosion is significant and the action of corrosion determines the total degree of synergy in tribocorrosion system. Furthermore, the friction coefficient is greatly reduced through duplex treatment coatings during tribocorrosion test due to the good resistance to the seawater and the graphitization effect produced by TiSiCN layer.

The CrCN coatings have been prepared by multi-arc ion plating technology with different bias voltages on 316 L, TC4 and H65 substrates, respectively. The prepared CrCN coatings have been characterized by XRD, SEM, and EDS, respectively. The mechanical properties, electrochemical corrosion behavior, and tribological performance of prepared coatings were tested by microhardness tester, scratch tester, electrochemical workstation, and friction and wear tester, respectively. Results show that the CrCN coatings with bias voltage of −50 V presented the finer grain size, denser structure, better comprehensive mechanical properties and friction, and better corrosion resistance than the CrCN coatings with a bias voltage of −30 V. The coating on TC4 substrate show the lower hardness, the better adhesion, the better electrochemical properties and tribological properties than that on 316 L substrate. The coatings based on H65 Cu substrate presented the worst electrochemical and wear properties. The CrCN coating with a bias voltage of −50 V on TC4 substrate is an optimal candidate in artificial seawater for tribocorrosion.

A NiCoCrAlYTa coating was synthesized successfully onto a Ni-based superalloy by arc ion plating (AIP) technology. After accomplishing the coating, a vacuum heat treatment was carried out and the coating was then subjected to isothermal oxidation in air at 1050 °C for up to 200 h. The microstructural evolution and interface diffusion behavior were studied systematically using transmission electron microscopy (TEM) and scanning transmission electron microscopy-energy dispersive X-ray microanalysis (STEM-EDX) combined with other characterization methods, such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive spectroscopy (EDS). The results revealed that the thickness of the obtained NiCoCrAlYTa coating was 60–70 μm and the coating was primarily composed of γ-Ni and γ’-Ni3Al phases. During the oxidation process, the Al content was gradually reduced and the oxide scales eventually formed a multi-layer structure, consisting of an outer layer of mixed oxides, namely α-Al2O3, Cr2O3, and NiO, and an inner dense α-Al2O3 layer with columnar microstructure. More particularly, after 100 and 200 h of oxidation, a Ta-riched oxide and (Al0.9Cr0.1)2O3 were detected, respectively. The finding provides solid experimental evidence demonstrating that the external diffusion of cations during the growth of oxide scales plays a greater role in the oxidation of the coating compared with the internal diffusion of oxygen.

A MoSi2 coating was prepared on Nb-10Hf-1Ti alloys by a two-step process. The first step was arc ion plating (AIP) of the Mo layer, and the second step was halide-activated pack cementation (HAPC) of Si. The coating is composed of an outer layer of MoSi2 and an inner bond layer. After oxidation testing at 1200 °C for 100 h in a static air atmosphere, the mass gain of the coated specimen was 0.64 mg/cm2. The good oxidation resistance of the MoSi2 coating is attributed to the protective SiO2 scale generated by the oxidation process.

500-nm-thick aluminum nitride (AlN) polycrystalline films were deposited on amorphous glass substrates at a substrate temperature of 200 °C by ion plating (IP) with direct-current (DC) arc discharge, radio frequency (RF) and DC reactive magnetron sputtering (MS). The IP technique enables a very high deposition rate of 113 nm/min compared with that of MS techniques. The structural properties of AlN films were investigated by X-ray diffraction (XRD), Raman spectroscopy, and electron probe micro analyzer (EPMA) measurements. XRD results show that AlN films with a columnar grain structure deposited by IP have a texture with a well-defined (0001) orientation between grains normal to the substrate, whereas AlN films grown by MS have a mixture of (0001) planes and planes with other orientations. Raman spectroscopy and XRD measurement results revealed high residual compressive stress in AlN films deposited by IP compared with that in AlN films grown by MS. The analysis of the data obtained by EPMA measurement showed that IP produces AlN films with a small amount of remaining oxygen species, whereas MS produces AlN films with a large amount of residual oxygen species.

In this work, thick, single-layer TiN films were fabricated on beryllium balls by using short, linear, magnetic-filtered multi arc ion plating under cleaning biases that ranged from 400 to 800 V in 100 V intervals. The relationship between cleaning bias and the performance of these films was investigated in detail, and the results indicate that performance depends strongly on the cleaning bias. The single-layer TiN films were 28 μm thick and had a high Vickers hardness of 2300 and a high critical load of 86.2 N at 700 V. Moreover, analysis by x-ray photoelectron spectroscopy revealed that there was no free elemental N and Ti in the thick TiN films, which indicated that thick, single-layer TiN films were mainly composed of Ti N, Ti O and Ti O N.

The effects of nickel ion implantation on surface structure as well as resistance against corrosion for CrN coatings deposited by arc ion plating are investigated. The objective of this work is to optimize the deposition condition for the best corrosion resistance. In this experiment, nickel ions with energy of 20 keV were implanted into CrN coatings by doses from 1 × 1017 to 1 × 1018 ions/cm2. X-ray diffraction analysis was applied for both the metallic analysis and the study of new structures created during the implantation. Atomic force microscopy and corrosion analysis were utilized to compare the roughness and the corrosion resistance prior to and after the implantation, respectively. The results indicate that nickel ion implantation can greatly improve the resistance against corrosion. After the corrosion test, the surface morphology and composition of the coatings were examined by the scanning electron microscopy with an energy dispersive spectroscopy, which confirmed the existence of the implanted nickel in the coatings.

TiN/TiAlN multilayer coatings with various bilayer numbers were deposited on AISI 410 martensitic stainless steel using ion source enhanced hybrid arc ion plating system. The influences of different bilayer numbers on structure, mechanical properties and corrosion behaviors of TiN/TiAlN multilayer coatings were investigated comparatively. The as-deposited coatings were predominantly composed of fcc-TiN and solid solution (Ti, Al) N phases with (111) preferred orientation, and the growing tendency towards preferential orientation decreased as the increase of bilayer numbers. With increasing bilayer numbers, microhardness of the coatings was enhanced gradually for the increased interfaces and refined crystals, reaching a maximum of 3800 HK0.025 at the coating with 12 bilayers. Multilayer coatings exhibited an abrasive wear mechanism against WC pair, and possessed an excellent tribological performance in comparison to MSS substrate. According to electrochemical results, the coating with bilayer number of 12 presented a high free corrosion potential combined with the lowest corrosion current density, highest polarization resistance, highest protective efficiency and largest charge transfer resistance than that of other bilayer numbers owing to the increased layered interfaces and high structural density.

Si-containing, AlCrSiN gradient coatings are promising candidates for use in advanced cutting tools. An investigation was conducted on several such coatings, including their dry sliding friction, dry sliding wear, adhesion strength, and wet milling performance. Three different coatings were deposited by multi-arc ion plating. Scanning and transmission electron microscopy of AlCrSiN gradient coatings revealed changes in their Si contents, grain sizes, and microstructures as a function of depth below the surface. The best AlCrSiN gradient coatings exhibited higher adhesion strength and high hardness (H ~33 GPa) combined with a low elastic modulus (E ~326 GPa) and a high ratio of H3 to E2 (~0.3402 GPa). They also had low friction coefficients and wear rates against alumina counter-bodies under various normal loads. It is proposed that the improved wear resistance of the AlCrSiN gradient coating was due to a decreased probability of peeling. This AlCrSiN gradient coating also possessed the greatest cutting life due to a reduction in the contributions from abrasive and adhesive wear. Based on this work, the cutting performance of coated tools could be improved by the proper design of Si-containing gradient microstructures.

Surface modification is considered to be an important approach for improving the antibacterial activity and cytocompatibility of titanium alloys. Silver has been extensively studied for improving the antibacterial ability of implants due to its powerful antibacterial activity. Therefore, in this study, TiN/Ag multilayers were deposited on the surface of medical titanium alloys by a multi-arc ion plating system with the top TiN, Ag, and TiN and Ag composite (TiN-Ag) layers. The structure and chemical characteristics of the three groups were investigated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) respectively. Scanning electron microscopy (SEM) was used to elucidate the cross-section structures of the multilayers. The surface topography, roughness, friction coefficients, hardness and elastic modulus values for different top layers were obtained by atomic force microscopy (AFM), wear tester and nanoindenter. The biological assays, including cytocompatibility experiments and antibacterial activity, were evaluated by MC3T3-E1 cells, bovine serum albumin (BSA) and Escherichia coli (E. coli) in vitro. These results confirm that the TiN/Ag multilayers with the exposed TiN-Ag top layer show excellent mechanical properties, antibacterial properties and ideal cytocompatibility, leading to the potential application of these multilayers as body-implanted materials.

This research mainly focuses on the development of Al-based binary Ti/Al and Zr/Al reactive multilayer films (RMFs). Magnetron sputtered deposited RMFs were investigated by considering two important aspects of large freestanding film synthesis and the analysis of the self-propagating reaction. Here, Ti/nAl (n = 1–3) RMFs with different Al molar ratios and 1Zr/1Al RMFs with various bilayer thicknesses of 20–55 nm were deposited on the copper substrate. To fabricate thick films, two types of processes of the continuous coating (process-1) and the coating with interval etching (process-2) were introduced in the Magnetron Sputter Ion Plating (MSIP) method. Microstructural characterization of as-deposited RMFs by scanning electron microscopy and transmission electron microscopy reveals the columnar microstructural morphology with coherent reactant layers. The coating process-2 exhibits the consistent and uniform film growth through the cross-section compared to the process-1. The use of a cost-effective copper substrate and the modification of the coating process in this work assure the fabrication of about 10 cm long and 45 µm thick freestanding Zr/Al RMFs with homogeneous film growth. Then, self-propagating reaction properties were analyzed after an electrical arc ignition in air. A high-speed microscope and a two-color pyrometer were used to record the reaction propagation and temperature profile simultaneously. Ti/Al and Zr/Al RMFs exhibit the maximum reaction velocity of 2.6 ± 0.6 m/s and 1.22 ± 0.4 m/s, respectively. The maximum reaction temperatures of 1581–1707 °C were found in Zr/Al RMFs, whereas Ti/nAl RMFs show the reaction temperature in the range of 1215–1298 °C. The reaction front velocity and temperature of the self-propagating reaction show the dependency on the reactants combinations, compositions, and bilayer thickness. Furthermore, this work describes the component and morphology dependent reaction properties of Zr/Al and Ti/Al RMFs and a simple approach to fabricate large sized freestanding reactive films.

The effect of N2 flow rate on structural, composition, deposition rate, electrical and infrared properties of the multi-layer AlCrN/Cr/AlCrN tandem coatings have been studied. The coatings were designed and prepared by a cathodic arc ion plating system at various N2 flow rates for low emissivity applications. The results showed that the thickness of AlCrN layers decreased continuously with increasing N2 flow rate. Structure and elemental composition of the deposited coatings strongly depended on N2 flow rate. X-ray diffraction analysis showed that for 10–80 sccm, the coatings exhibited a single (fcc) phase, for 120–160 sccm, an amorphous phase was obtained. The phase formation has been confirmed by transmission electron microscopy diffraction patterns. As for electrical resistivity, the AlCrN layers turned from conductive, semiconductive, to dielectric behavior. In practice for low emissivity applications, the deposited multi-layer coatings exhibited emissivity values among 0.0748–0.1193, which rose with increased N2 flow rate. Among all the phases, the coating with an amorphous AlCrN layer (160 sccm) presented an outstanding thermal stability and had an emissivity of 0.1194 even after annealing at 800 °C for 10 h in air. It was observed that the amorphous AlCrN layer effectively controlled the inward diffusion of O and the outward diffusion of Cr, Al and Ni from substrate, which rendered this multi-layer coating a potential material for low emissivity applications at high temperature.

NiCrAl overlay coatings have been manufactured by means of conventional electrodeposition of Ni into a porous electrophoretic deposition layer of CrAl nanoparticles. The NiCrAl coatings are compact with a uniform distribution of Cr and Al elements in nano-length scale. They can thermally grow alumina scales in air at 1000 °C, with parabolic oxidation constants as low as that of the ternary coating counterparts prepared by means of physical vapor deposition technologies such as sputtering and arc ion plating.

The TiSiN-Cu nanocomposite coating was deposited on F690 steel substrate by arc ion plating. The structure and composition, tribocorrosion behavior and anti-microbiologically influenced corrosion (MIC) properties of TiSiN-Cu coating were investigated. The results show that the TiSiN-Cu coating has unique nanocomposite structures. The results of tribocorrosion show that the potential and current change of F690 steel and TiSiN-Cu coatings tend to be opposite. The reason is that the F690 steel is non-passivated metal and the TiSiN-Cu coating has passivation phenomenon. The TiSiN-Cu coating possesses excellent tribocorrosion resistance. Cu ion released from TiSiN-Cu coating can effectively inhibit the corrosion caused by SRB.