Search Results (113)

To address the limitations of single-layer nitride coatings, such as poor load adaptability and low long-term durability, MoN/TiN multilayer coatings were prepared via high-power impulse magnetron sputtering (HiPIMS). HiPIMS produces highly ionized plasmas that enable intense ion bombardment, yielding nitride films with enhanced mechanical strength, durability, and thermal stability versus conventional methods. The multilayer coating demonstrated a low coefficient of friction (COF, ~0.4) and wear rate (1.31 × 10⁻⁷ mm³/[N·m]). In contrast, both TiN and MoN coatings failed at 5 N and 10 N loads, respectively. Under increasing loads, the multilayer coating maintained stable wear rates (1.84–3.06 × 10⁻⁷ mm³/[N·m]) below 20 N, and ultimately failed at 25 N. Furthermore, the MoN layer contributes to COF reduction. Grazing-incidence X-ray diffraction analysis confirmed the enhanced crystallographic stability of the multilayer coating, thereby revealing a dominant (111) orientation. The multilayer architecture suppresses crack propagation while effectively balancing hardness and toughness, offering a promising design for extreme-load applications. Full article

CoCrMo alloys are interesting materials for implantable devices due to their favorable mechanical properties, high wear resistance, and good biocompatibility with the human body. Recent studies have demonstrated the possibility to further increase their wear resistance with an innovative approach consisting of nitriding treatments by the High-Power Impulse Magnetron Sputtering (HiPIMS) technique. Given the novelty of this treatment, it is relevant to develop a preliminary sustainability analysis of the processes to highlight the total environmental impact and to evaluate possible strategies to decrease it. Here, a Life Cycle Assessment (LCA) of HiPIMS nitriding treatments of CoCrMo alloys using a tantalum or molybdenum target is presented. The main impact driver in all impact categories was the electrical consumption of the vacuum apparatus and cooling system of HiPIMS instrumentation with a 45–47% and 37–39% contribution for Ta-based, and 39–40% and 41–42% for Mo-based treatments, respectively. Climate Change was found to be the most impacted category, followed by Resource Use both for Mo and Ta nitriding targets. Therefore, some perspectives to enhance the environmental sustainability of the synthesis process have been considered by means of a sensitivity analysis. Moreover, a Critical Raw Material (CRM) assessment is discussed, providing a complete sustainability evaluation of the proposed HiPIMS treatments. Full article

Plasma nitriding (PN) is often used to enhance the mechanical properties (surface hardness, wear and corrosion resistance) of bulk alloys. High-quality AlCrN hard coatings were obtained using high-power pulsed magnetron sputtering (HiPIMS) technology. This study proposes a combination of two surface treatment methods (plasma nitriding and hard coating deposition) in a continuous plasma process to optimize the application and service life of cutting tools. The main feature of this study is to verify the mechanical properties and adhesion strength of nitride tungsten carbide (WC-Co) bulk at a lower temperature (∼300 °C) and shorter time (0.5 to 1.5 h) of PN treatment. After 1.5 h of PN treatment on the WC-Co substrate without subsequent coating, the ultra-thin WN_x diffusion interlayer (thickness ∼11.5 nm) on the subsurface was directly observed via TEM analysis, and the types of chemical bonding were confirmed by XPS analysis. Vickers analysis indicated that the surface hardness of the nitrided WC-Co substrate was enhanced by PN treatment from 1534 to 2034 Hv. The AlCrN coating deposited on the nitrided WC-Co substrate significantly enhances the surface mechanical properties, including adhesion strength (increasing from 70 to 150 N), hardness (rising from 2257 to 2568 HV), and wear resistance (with the wear rate decreasing from 14.5 to 3.4 × 10⁻⁸ mm³/Nm). Composite surface technology has a high commercial application value because it enhances the value of products under the existing equipment of manufacturers. Full article

This study investigates the effects of substrate bias voltage on the properties of titanium nitride (TiN) and titanium oxynitride (TiON) thin films deposited via High-Power Impulse Magnetron Sputtering (HiPIMS). The structure and morphology of the obtained coatings were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). TiN coatings exhibited hydrophilic behavior, while TiON coatings demonstrated hydrophobic characteristics. Electrochemical corrosion testing in Hank’s solution revealed superior corrosion resistance for TiON films deposited at −100 V, indicating their potential for biomedical applications. The observed differences in wettability and corrosion resistance are attributed to the influence of substrate bias voltage on the films’ microstructure and surface chemistry. Full article

In this study, Cr coatings, CrN coatings, and CrN/Cr multi-layer coatings were deposited on the surface of Zr-4 alloy by high-power impulse magnetron sputtering (HiPIMS). We have investigated the effect of coating structure on the microstructure, mechanical properties, and high-temperature steam oxidation properties of coatings. The results show that the single-layer CrN coating has higher hardness but performs poorly in high-temperature steam oxidation compared to the Cr coating due to its greater brittleness, which makes it prone to cracking and spalling in high-temperature steam environments and provides a channel for Zr diffusion. In multi-layer coatings, however, they form a fine columnar crystal structure and a smoother surface, and the more layers there are, the better the mechanical properties and resistance to high-temperature steam oxidation of the coating. In a high-temperature steam environment, the CrN layer decomposes to form Cr₂N and N₂, and the N atoms diffuse inwards and react with Zr to form an α-Zr(N) layer, which restricts interdiffusion between Cr and Zr and blocks the diffusion of O into the substrate. Therefore, (CrN/Cr)_n coatings with a multi-layer structure have excellent high-temperature steam corrosion resistance. Full article

High-Power Impulse Magnetron Sputtering (HiPIMS) has emerged as an excellent technology for producing high-quality nitride coatings, such as aluminum nitride (AlN), titanium nitride (TiN), chromium nitride (CrN), and silicon nitride (SiN), and composite nitride coatings such as titanium aluminum nitride (TiAlN), TiAlNiCN, etc. These coatings are known for their exceptional hardness, thermal stability, and corrosion resistance. These make them ideal for high-performance applications. HiPIMS distinguishes itself by generating highly ionized plasmas that facilitate intense ion bombardment, leading to nitride films with superior mechanical strength, durability, and enhanced thermal properties compared to traditional deposition techniques. Critical HiPIMS parameters, including pulse duration, substrate bias, and ion energy, are analyzed for their influence on enhancing coating density, adhesion, and hardness. The review contrasts HiPIMS with other deposition methods, highlighting its unique ability to create dense, uniform coatings with improved microstructures. While HiPIMS offers substantial benefits, it also poses challenges in scalability and process control. This review addresses these challenges and discusses hybrid, bipolar, and synchronized HiPIMS solutions designed to optimize nitride coating processes. Hybrid HiPIMS, for instance, combines HiPIMS with other sputtering techniques like DCMS or RF sputtering to achieve balanced deposition rates and high-quality film properties. Bipolar HiPIMS enhances process stability and film uniformity by alternating the polarity, which helps mitigate charge accumulation issues. Synchronized HiPIMS controls precise pulse timing to maximize ion energy impact and improve substrate interaction, further enhancing the structural properties of the coatings. Hence, to pave the way for future research and development in this area, insights of the HiPIMS have been presented that underline the role of HiPIMS in meeting the demanding requirements of advanced industrial applications. Overall, this review article comprehensively analyzes the recent strategies and technological innovations in HiPIMS and highlights the significant potential of HiPIMS for advancing the nitride coating field. Full article

We used high-power impulse magnetron sputtering (HiPIMS) to deposit tungsten carbide films for superior wear protection in abrasive environments. In order to sample different W-to-C ratios more efficiently, a combinatorial approach was chosen. A single sputter target with two equal segments was used, consisting of an upper tungsten and lower graphite segment. This allowed us to vertically sample various elemental compositions in just one deposition run without creating graphitic nano-layers by rotating the substrate holder. The substrate bias voltage, being one of the most effective process parameters in physical vapor deposition (PVD), was applied in both constant and pulsed modes (the latter synchronized to the target pulse). A direct comparison of the different modes has not been performed so far for HiPIMS W-C (separated W and C targets). The resulting coating properties were mainly analyzed by nano-hardness testing and X-ray diffraction. In general, the W₂C phase prevailed in tungsten-rich coatings with pulsed bias, leading to slightly higher tungsten contents. Hardness reached maximum values of up to 35 GPa in the center region between the two segments, where a mix of W₂C and WC_1-x phases occurs. With pulsed bias, voltage hardnesses are slightly higher, especially for tungsten-rich films. In those cases, compressive stress was also found to be higher when compared to constant bias. Erosive wear testing by blasting with alumina grit showed that the material removal rate followed basically the coating’s hardness but surprisingly reached minimum wear loss for W₂C single-phase films just before maximum hardness. In contrast to previous findings, low friction that requires higher carbon contents of at least 50 at. % is not favorable for this type of wear. Full article

Uncrystallized indium-gallium-zinc-oxide (InGaZnO) thin-film transistors (TFTs) combined with an aluminum nitride (AlN) dielectric have been used to promote performance and steadiness. However, the high deposition temperature of AlN films limits their application in InGaZnO flexible TFTs. In this work, AlN layers were deposited via low-temperature plasma-enhanced atomic layer deposition (PEALD), and InGaZnO films were fabricated via high-power impulse magnetron sputtering (HIPIMS). The band alignment of the AlN/InGaZnO heterojunction was studied using the X-ray photoemission spectrum and ultraviolet visible transmittance spectrum. It was found that the AlN/InGaZnO system exhibited a staggered band alignment with a valence band offset ΔE_v of −1.25 ± 0.05 eV and a conduction band offset ΔE_c of 4.01 ± 0.05 eV. The results imply that PEALD AlN could be more useful for surface passivation than a gate dielectric to promote InGaZnO device reliability under atmospheric exposure. Full article

Water vapor-impermeable AlON/HfO_x bilayer films were constructed through a hybrid high-power impulse magnetron sputtering (HiPIMS) and radio-frequency magnetron sputtering process (RFMS), applied as an encapsulation of flexible electronics such as organic photovoltaics. The deposition of monolithic and amorphous AlON films through HiPIMS was investigated by varying the duty cycles from 5% to 20%. At an accelerated test condition, 60 °C, and 90% relative humidity, a 100 nm thick monolithic AlON film prepared using a duty cycle of 20% exhibited a low water vapor transmission rate (WVTR) of 0.0903 g m⁻² day⁻¹ after testing for 336 h. Furthermore, after introducing a nanocrystalline HfO_x film through RFMS, a 214 nm thick AlON/HfO_x bilayer film reached the lowest WVTR of 0.0126 g m⁻² day⁻¹. Full article

In the present research, hexagonal boron nitride (h-BN) films were deposited by reactive high-power impulse magnetron sputtering (HiPIMS) of the pure boron target. Nitrogen was used as both a sputtering gas and a reactive gas. It was shown that, using only nitrogen gas, hexagonal-boron-phase thin films were synthesized successfully. The deposition temperature, time, and nitrogen gas flow effects were studied. It was found that an increase in deposition temperature resulted in hydrogen desorption, less intensive hydrogen-bond-related luminescence features in the Raman spectra of the films, and increased h-BN crystallite size. Increases in deposition time affect crystallites, which form larger conglomerates, with size decreases. The conglomerates’ size and surface roughness increase with increases in both time and temperature. An increase in the nitrogen flow was beneficial for a significant reduction in the carbon amount in the h-BN films and the appearance of the h-BN-related features in the lateral force microscopy images. Full article

Proton Exchange Membrane Fuel Cells (PEMFCs) are promising technology to convert chemical energy from dihydrogen in electrical energy. HT-PEMFCs are working at high temperatures (above 120 °C) and with doped orthophosphoric acid H₃PO₄ PBI membranes. In such devices, bipolar metallic plates are used to provide reactive gas inside the fuel cell and collect the electrical current. The metallic elements used as bipolar plates, end plates, and interconnectors in acid electrolyte and gaseous fuel cells are severely damaged by a combination of oxidation (due in particular to the use of oxygen, whether pure or contained in the air) and corrosion (due in particular to acid effluents from the electrolyte). This degradation rapidly leads to the loss of the electrical conductivity of the metallic elements and today requires the use of very specific alloys, possibly coated with pure gold. The solution investigated in the present study is the use of a protective coating based on single-phase nitrides obtained by reactive magnetron sputtering or reactive HiPIMS (High-Power Impulse Magnetron Sputtering). The influence of the microstructure on the physical–chemical properties was studied. The electrochemical properties were quantified following two approaches. First, the corrosion current of the developed coatings was measured at room temperature and at higher temperatures using the Linear Sweep Voltammetry (LSV) technique. Then, Electrochemical Impedance Spectroscopy (EIS) measurements were performed to better identify and evaluate their corrosion-resistance performances. Full article

The present study aims to investigate the advantages of diamond-like carbon (DLC) films in reducing friction and lubrication to address issues such as the low surface hardness, high friction coefficients, and poor wear resistance of titanium alloys. Cr-doped DLC films were deposited by high-power impulse magnetron sputtering (HiPIMS) in an atmosphere of a gas mixture of Ar and C₂H₂. The energy of the deposited particles was controlled by adjusting the target powers, and four sets of film samples with different powers (4 kW, 8 kW, 12 kW, and 16 kW) were fabricated. The results showed that with an increase in target power, the Cr content increased from 3.73 at. % to 22.65 at. %; meanwhile, the microstructure of the film evolved from an amorphous feature to a nanocomposite structure, with carbide embedded in an amorphous carbon matrix. The sp²-C bond content was also increased in films, suggesting an intensification of the film’s graphitization. The hardness of films exhibited a trend of initially increasing and then decreasing, reaching the maximum value at 12 kW. The friction coefficient and wear rate of films showed a reverse trend compared to hardness variation, namely initially decreasing and then increasing. The friction coefficient reached a minimum value of 0.14, and the wear rate was 2.50 × 10⁻⁷ (mm³)/(N·m), at 8 kW. The abrasive wear was the primary wear mechanism for films deposited at a higher target power. Therefore, by adjusting the target power parameter, it is possible to control the content of the metal and sp²/sp³ bonds in metal-doped DLC films, thereby regulating the mechanical and tribological properties of the films and providing an effective approach for addressing surface issues in titanium alloys. Full article

To obtain a high-performance extended gate field-effect transistor for pH detection, hafnium nitride (HfN) was first fabricated on an indium tin oxide on polyethylene terephthalate (ITO/PET) substrate using a high-power impulse magnetron sputter system (HiPIMS) in this study. It can be easily applied in biomedical diagnostic and environmental monitoring applications with the advantages of flexible, disposable, cost-effective, and reliable components. Various duty cycle conditions in HiPIMSs were designed to investigate the corresponding sensing performance and material properties including surface morphology and composition. As the duty cycle increased, the grain size of HfN increased. Additionally, X-ray photoelectron spectroscopy (XPS) analysis illustrated the presence of HfO_xN_y on the deposited HfN surface. Both behaviors could result in a better pH sensing performance based on the theory of the site-binding model. Subsequently, HfN with a 15% duty cycle exhibited excellent pH sensitivity and linearity, with values of 59.3 mV/pH and 99.8%, respectively; its hysteresis width and drift coefficient were −1 mV and 0.5 mV/h, respectively. Furthermore, this pH-sensing performance remained stable even after 2000 repeated bending cycles. These results indicate the potential and feasibility of this HiPIMS-deposited HfN for future wearable chemical applications. Full article

The machining of austenitic stainless steel alloys is usually characterized by high levels of adhesion and built-up edge; therefore, improving tribological conditions is fundamental to obtaining higher tool life and better surface finish. In this work, three different Al_0.6Ti_0.4N coatings are compared, two deposited by Cathodic Arc Evaporation (CAE) and one with High-Power Impulse Magnetron Sputtering (HiPIMS). The effects of the micromechanical properties and the microstructure of the coatings were then studied and related to the machining performance. Both arc-deposited coatings (CAE 1 and 2) exhibited similar average tool life, 127 min and 128 min, respectively. Whereas the HiPIMS lasted for only 21.2 min, the HiPIMS-coated tool had a much shorter tool life (more than six times lower than both CAE coatings) due to the intense adhesion that occurred in the early stages of the tool life. This higher adhesion ultimately caused built-up edge and chipping of the tool. This was confirmed by the cutting forces and more deformation on the shear band and undersurface of the chips, which are related to higher levels of friction. The higher adhesion could be attributed to the columnar structure of the HiPIMS and the (111) main texture, which presents a higher surface energy when compared to the dominant (200) from both arc depositions. Studies focused on tribology are necessary to further understand this relationship. In terms of micromechanical properties, tools with the highest plasticity index performed better (CAE 2 = 0.544, CAE 1 = 0.532, and HiPIMS = 0.459). For interrupted cutting machining where adhesion is the main wear mechanism, a reserve of plasticity is beneficial to dissipate the energy generated during friction, even if this was related to lower hardness levels (CAE 2 = 26.6 GPa, CAE 1 = 29.9 GPa, and HiPIMS = 33.6 GPa), as the main wear mechanism was adhesive and not abrasive. Full article

It is usually difficult to realize high mobility together with a low threshold voltage and good stability for amorphous oxide thin-film transistors (TFTs). In addition, a low fabrication temperature is preferred in terms of enhancing compatibility with the back end of line of the device. In this study, α-IGZO TFTs were prepared by high-power impulse magnetron sputtering (HiPIMS) at room temperature. The channel was prepared under a two-step deposition pressure process to modulate its electrical properties. X-ray photoelectron spectra revealed that the front-channel has a lower Ga content and a higher oxygen vacancy concentration than the back-channel. This process has the advantage of balancing high mobility and a low threshold voltage of the TFT when compared with a conventional homogeneous channel. It also has a simpler fabrication process than that of a dual active layer comprising heterogeneous materials. The HiPIMS process has the advantage of being a low temperature process for oxide TFTs. Full article