Search Results (5)

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

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

This work aims to provide information about the deposition of gold via bipolar high-power impulse magnetron sputtering (HIPIMS) in order to identify suitable process parameters. The influences of voltage, pulse length and the kick-pulse on an argon–gold plasma during a bipolar high-power impulse magnetron sputtering deposition process were analysed via optical emission spectroscopy (OES) and oscilloscope. The voltage was varied between 700 V and 1000 V, the pulse length was varied between 20 µs and 100 µs and the process was observed once with kick-pulse and once without. The influence of the voltage on the plasma was more pronounced than the influence of the pulse width. While the intensity of several Au I lines increased up to 13-fold with increasing voltages, only a less-than linear increase in Au I brightness with time could be identified for changes in pulse length. The intensity of excited argon is only minimally affected by changes in voltages, but follows the evolution of the discharge current, with increasing pulse lengths. Contrary to the excited argon, the intensity emitted by ionized argon grows nearly linearly with voltage and pulse length. The reverse polarised pulse mainly affects the excited argon atoms in the plasma, while the influence on the ionized argon is less pronounced, as can be seen in the the spectra. Unlike the excited argon atoms, the excited gold atoms appear to be completely unaffected by the kick-pulse. No ionization of gold was observed. During the pulse, a strong rarefaction of plasma takes place. Very short pulses of less than 50 µs and high voltages of about 1000 V are to be preferred for the deposition of gold layers. This paper offers a comprehensive overview of the gold spectrum during a HIPIMS process and makes use of optical emission spectroscopy as a simple measuring approach for evaluation of the reverse polarized pulse during a bipolar process. Future uses of the process may include the metallization of polymers. Full article

This manuscript introduces and experimentally demonstrates a novel concept of selective metal ion irradiation by combining bipolar HIPIMS with conventional DC magnetron sputtering operation and simple DC biasing. The addition of the positive pulse to a conventional HIPIMS discharge accelerates the predominantly metal ions created during the negative HIPIMS phase with an energy proportional to the positive pulse amplitude and ionization state. Two distinct metal elements with large difference in atomic mass (Cr and Nb) are used on this work to irradiate a TiAlN matrix which is being deposited by conventional DCMS. The positive acceleration voltages used for both Cr and Nb discharges were varied between 0 to +200 V to analyze the influence of Nb and Cr metal ion irradiation on the mechanical and microstructural properties of TiAlN films. Even though the total metal ion incorporation into the TiAlN matrix for both Cr and Nb is less than 10% at%, strong effects are observed on the resulting film properties. It was observed that use of the lighter metal ion Cr is more beneficial than the heavier metal ion Nb. The Cr bombardment allows a hardness improvement from 7 to 22 GPa as well as a reduced film accumulated stress at the highest positive acceleration voltage. From the XRD measurements it is observed that the Cr atoms are inserted into the TiAlN cubic matrix maintaining its crystalline structure. However, the bombardment with the high-mass metal ion (Nb) promotes the deformation of the cubic TiAlN matrix, resulting in a spinodal decomposition and further degradation of the crystalline structure with the appearance of the hexagonal wurtzite-type Al-rich phase. This is also translated to the resulting film mechanical properties, as hardness rapidly decreases from 25 to 10 GPa and stress increases linearly with the positive voltage acceleration. Full article

Despite its great potential for thin films deposition and technological applications, the HiPIMS technology has its own limitations including the control of ion energy and flux towards the substrate when coping with the deposition of electrical insulating films and/or the deposition onto insulating/electrically grounded substrates. The bipolar-HiPIMS has been recently developed as a strategy to accelerate the plasma ions towards a growing film maintained at ground potential. In this work, the benefits of bipolar-HiPIMS deposition onto floating or nonconductive substrates are explored. The effect of bipolar-HIPIMS pulsing configuration, magnetic balance-unbalance degree, and substrate’s condition on plasma characteristics, microstructure evolution, and mechanical properties of CrN coatings was investigated. During the deposition with a balanced magnetron configuration, a significant ion bombardment effect was detected when short negative pulses and relative long positive pulses were used. XRD analysis and AFM observations revealed significant microstructural changes by increasing the positive pulse duration, which results in an increase in hardness from 7.3 to 16.2 GPa, during deposition on grounded substrates, and from 4.9 to 9.4 GPa during the deposition on floating substrates. The discrepancies between the hardness values of the films deposited on floating substrates and those of the films deposited on grounded substrates become smaller/larger when a type I/type II unbalanced magnetron configuration is used. Their hardness ratio was found to be 0.887, in the first case, and 0.393, in the second one. Advanced application-tailored coatings can be deposited onto floating substrates by using the bipolar-HiPIMS technology if short negative pulses, relative long positive pulses together with type I unbalanced magnetron are concomitantly used. Full article