Pulsed Magnetron Sputtering Process Research Articles

Investigation and Band Gap Analysis of Pulsed Dc Magnetron Sputtered Diamond‐Like Carbon to Enhance Contact‐Electrification and Durability of Triboelectric Nanogenerators

AbstractThis work details the triboelectric characteristics of diamond‐like carbon (DLC) film where a proportioned sp3:sp2 bond ratio is engineered through a patented pulsed DC magnetron sputtering process to achieve a durable commercial energy harvesting material. A triboelectric nanogenerator (TENG) is fabricated by creating the triboelectric interface between DLC and PTFE. The presence and synchronization of σ – σ and σ – π bonds between DLC‐PFTE contact surface amplify the electronic cloud overlap between their atoms leading to an enhancement of the triboelectric surface charge density. The inherent hardness and reduced friction achieved through DLC and PTFE respectively prevent the mass transfer, and consequent power loss upon consecutive mechanical contact and achieves a stable electric power output of 141 mW m−2. The DLC durability achieved with PTFE in TENG demonstrates its significant potential as low frequency (1 – 10 Hz) energy harvesting devices and self‐/low‐power electronic devices and sensors. The paper uniquely contributes to a better understanding of the triboelectrification mechanism by insightfully detailing the band‐to‐band transition of electrons between the PTFE and DLC tribo‐interface, as well as discussing gap and frequency limitation of the tribo‐pair on the triboelectric charge yield, storage, transfer, and on the friction layer electric field.

Machine learning based model for plasma prediction in high power pulsed magnetron sputtering processes

The coating development using physical vapor deposition (PVD) is time intensive and expensive. The coating processes are usually developed and improved based on the operator's experience. In order to improve the understanding of the processes during coating deposition, methods of plasma diagnostics can be used. However, this is time intensive and requires the installation of special diagnostics. The aim of the current study is to build a machine learning based model of PVD processes to predict the ionized to excited intensity ratio of the plasma species during the coating process. This enables a knowledge-based, cost-reduced process improvement. Based on measured data of different coating processes, the models were trained and tested in the current study. Therefore, a database was established by measuring process and plasma properties in hybrid processes of direct current magnetron sputtering and high power pulsed magnetron sputtering using an industrial coating unit. Different processes with variations of cathode powers and gas flows of the reactive gases oxygen and nitrogen were processed. The intensities of the ionized and excited species were measured using optical emission spectroscopy with six substrate side positioned collimators for spatial resolution to calculate the intensity ratios. The data was measured time resolved during the coating process. Compared to the measured data, the predictions show similar trends and values for the species within the coating chamber. The model was used to predict the influence of oxygen gas flow for CrAlON coating development. Furthermore, the models can be used for a more targeted process development. This can contribute to the application oriented adjustment of the coating processes and the coating properties.

Influence of the etching process on the coating performance in dry tribological contacts

Physical vapor deposition (PVD) coatings are utilized for wear protection of gears. The use of PVD coatings in unlubricated contacts is also the subject of several research efforts. A promising approach to reduce wear in dry tribological contacts is the combination of MoS2 and WS2 embedded in CrAlN. One possible way to deposit these coatings is the application of High Power Pulse Magnetron Sputtering (HPPMS) process combined with direct current Magnetron Sputtering (dcMS). A challenge by depositing these coatings with an HPPMS/dcMS process is a sufficient adhesion between the coating and the substrate. The present study focuses on the influence of the etching process on the performance of CrAlN + Mo:W:Sg coatings in dry tribological contacts. Before coating deposition, the substrates were pretreated inside the vacuum chamber by different etching processes. During booster etching, which increases the Ar ionization, the substrate bias UB was varied between UB = −150 and UB = −250 V with steps of ΔUB = −50 V. Furthermore, an HPPMS metal ion etching process was used after booster etching at UB = −150 V for these processes. For HPPMS metal ion etching, the number of HPPMS cathodes was varied between one and two. With respect to the etching process, the morphology, surface roughness, compound adhesion by means of the scratch test as well as the coefficient of friction, and the wear volume of the subsequently deposited coatings were investigated. When increasing the substrate bias UB during booster etching, a reduced compound adhesion was found. Moreover, an increased wear volume was observed after pin-on-disk (PoD) tests. For metal ion etching with one activated HPPMS cathode, the wear volume after the PoD test was decreased compared to the pure booster etching processes. When increasing the number of HPPMS cathodes during metal ion etching, the compound adhesion decreased slightly. The wear volume after PoD tests, in contrast, increased. When only using one HPPMS cathode, the lowest wear volume of all investigated coatings was achieved. The present investigations show the potential of tailoring the etching process in order to increase the performance of PVD coatings. A customized HPPMS metal ion etching process can be used to improve the properties of well-established hard PVD coatings.

Self-lubricating CrAlMoN high performance tool coatings for machining of TiAl6V4

TiAl6V4 allows significant performance improvements in industrial applications. However, the machining is a considerable challenge due to low thermal conductivity, Young’s modulus and strong adhesion tendency. This leads to high thermal and mechanical loads on the cutting edge resulting in early tool failure. Today, uncoated cemented carbide tools are commonly used. However, temperature active physical vapor deposition (PVD) coatings like CrAlVN and CrAlMoN provide a promising approach to increase tool life. For this, the coating’s ability to form lubricating oxide phases is vital. In the present study, CrAlVN and CrAlMoN coatings were investigated to determine the more suitable version for increasing the economic efficiency of machining TiAl6V4. The coatings were deposited by hybrid direct current magnetron sputtering/high power pulsed magnetron sputtering (dcMS/HPPMS) processes. Morphology, thickness, chemical composition, indentation hardness, indentation modulus and oxide phase composition were analyzed. Moreover, friction and wear behavior of the coated tools were determined using a pin on disc (PoD) tribometer at various temperatures. Additionally, tool life and deformation behavior were analyzed after turning TiAl6V4. The CrAlVN and CrAlMoN coatings show a dense morphology and a smooth surface topography. Both variants have a good adhesion to the cemented carbide tools. For increased temperatures, the tribological analyses showed a reduction in the coefficient of friction. In case of CrAlMoN coated samples, a friction reduction compared to CrAlVN was observed at lower temperatures. Due to this, an increased tool life was achieved for CrAlMoN coated cutting inserts during turning of TiAl6V4.

Ag Surface and Bulk Segregations in Sputtered ZrCuAlNi Metallic Glass Thin Films.

We report on the formation of Ag-containing ZrCuAlNi thin film metallic glass (nano)composites by a hybrid direct-current magnetron sputtering and high-power pulsed magnetron sputtering process. The effects of Ag content, substrate temperature and substrate bias potential on the phase formation and morphology of the nanocomposites were investigated. While applying a substrate bias potential did not strongly affect the morphological evolution of the films, the Ag content dictated the size and distribution of Ag surface segregations. The films deposited at low temperatures were characterized by strong surface segregations, formed by coalescence and Ostwald ripening, while the volume of the films remained featureless. At higher deposition temperature, elongated Ag segregations were observed in the bulk and a continuous Ag layer was formed at the surface as a result of thermally enhanced surface diffusion. While microstructural observations have allowed identifying both surface and bulk segregations, an indirect method for detecting the presence of Ag segregations is proposed, by measuring the electrical resistivity of the films.

Pulse synchronized substrate bias for the High Power Pulsed Magnetron Sputtering deposition of CrAlN

In a high power pulsed magnetron sputtering (HPPMS) process a substrate bias is applied to affect the ions in the coating chamber and therefore the coating properties. For this reason the present experiments on an industrial scale coating unit are focusing on the identification of correlations between plasma and coating properties for a CrAlN process while using a pulsed substrate bias. The measurements regarding the plasma properties were carried out on the substrate side for a better understanding of the interaction of plasma and coating properties. These investigations should point out the significant potential of plasma diagnostics for measuring plasma properties to contribute to improved coating processes using pulsed substrate bias UB,p. For this purpose a substrate bias synchronized to the HPPMS pulse is used since the pulsed bias can influence ions of a specific species. It was found that the even low values of a pulsed substrate bias lead to high values of the Debye sheath thickness and thus to a shielding of opposite surfaces. For complex shaped substrates like cemented carbide cutting inserts a better coatability for pulsed substrate bias up to UB,p = -150 V was reached. Also increased values of the mean ion energy and the ion flux density were found compared to the use of a continuous substrate bias. Regarding the chemical composition a significant higher nitrogen content of the coatings was found when using a pulsed substrate bias compared to the use of a continuous substrate bias. Comparing the indentation hardness of a process using a pulsed substrate bias increased hardness values were found compared to the use of a continuous substrate bias. Generally, a significant change of both, plasma and coating properties was found when changing the mode of substrate bias.

Development of thermal barrier coatings using reactive pulsed dc magnetron sputtering for thermal protection of titanium alloys

There is a need to thermally protect titanium (Ti) alloys so that they can be used in high temperature environments, such as during hypersonic flight. In this study, a thermal barrier coating (TBC) system was developed using reactive magnetron sputtering. The coating system consists of a nickel chromium aluminum yttrium (NiCrAlY) bond coat and an yttria-stabilized zirconia (YSZ) top coat. The YSZ layer was deposited by reactive pulsed direct current (DC) magnetron sputtering a Zr-Y target in a gas mixture comprised of argon (Ar) and oxygen (O2). The pulsed DC magnetron sputtering process used closed-loop control with the cathode voltage as the feedback signal. The YSZ coatings were deposited at different cathode voltage feedback signals. The phase structure, elemental composition, microstructure, and thickness of the YSZ coatings were examined by different means. It was found that up to 69% of the metallic deposition rate can be achieved for obtaining near stoichiometric YSZ coatings. The YSZ coatings exhibit single cubic phase structure with an Y2O3% in the range from 6.5 mol% to 8 mol%. The developed TBC consists of a 2 μm Ti adhesion layer, a 30 μm NiCrAlY bond coat, and a 40 μm YSZ top coat deposited on Ti-6Al-4 V substrate. The NiCrAlY layer exhibited a dense structure and the YSZ layer exhibited a porous columnar grain structure. The TBC showed excellent adhesion on Ti-6Al-4 V. The coated Ti-6Al-4 V was annealed from 800 °C to 1000 °C in air to evaluate the thermal protection capability of the coating. No degradation of the TBC was observed and the Ti-6Al-4 V alloy preserved fine gains and desired mechanical properties up to 900 °C. However, the coating showed horizontal cracks and degradation at the interface between the Ti-6Al-4 V substrate and the NiCrAlY bond coat at 1000 °C. It is assumed that the outward diffusion of Al from the Ti alloy led to the coating failure at the interface. This indicates that new diffusion barrier layers are needed as part of the TBC system.

Structural, electrical and optical characteristics of CuSbSe2 films prepared by pulsed laser deposition and magnetron sputtering processes

CuSbSe2 is emerging as an alternative absorber for thin-film photovoltaics owing to its intrinsic p-type conductivity, proper band gap (~ 1.1 eV), high-absorption coefficient (> 104 cm−1) and low cost. Moreover, it is nontoxic and its compositional elements (Cu, Se and Sb) are abundant in the crust of earth. In the present work, Sb2Se3/Cu multilayers were deposited by pulsed laser deposition (PLD) followed by magnetron sputtering (MS). After that, the as-prepared multilayers were annealed in-suit in the MS chamber at different temperatures and times to obtain high-quality CuSbSe2 ternary compound. Five intermetallic compounds were generated in this process, including CuSbSe2, Sb2Se3, CuSe2, Cu2Se and Cu3SbSe3. Besides, it was found out that most CuSbSe2 ternary compound was generated when the as-prepared multilayers were annealed at 420 °C for 10 min. The crystallite size of CuSbSe2 phase increased with elevating annealing temperature, while more holes and gaps occurred when the annealing temperature exceeded 420 °C. The results of energy-dispersive spectrometer indicated the film was highly developed with nearly stoichiometric atomic ratio of 27.91:22.72:49.37 (Cu:Sb:Se). The electrical measurement results revealed the semiconducting nature of the film and gave the conductivity activation energy of 0.26 eV, 0.08 eV and 0.13 eV, respectively. The direct band gap of the annealed film was revealed as 1.13 eV, which fulfilled the Shockley–Queisser requirements for the efficient harvesting of the solar spectrum.

Effects of hard TiN under layer on mechanical properties and wear characteristics of TiN-WSx composite coating

Effect of hard TiN underlayer on mechanical and wear characteristics of TiN-WSx composite coating was studied. A mono layer TiN coating was also incorporated in the study as a reference. The coatings were synthesized with pulsed magnetron sputtering process. Structural properties were investigated with field emission scanning electron microscopy, energy dispersive spectroscopy, grazing incidence x-ray diffraction; mechanical properties with scratch adhesion test, nanoindentation test and finally tribological properties were studied with pin-on-disc test. TiN underlayer resulted in a more compact morphology of top TiN-WSx hard-lubricious layer. WS2 phase with (002) orientation coexisted with crystalline TiN for TiN-WSx composite both with and without hard TiN underlayer. Scratch test revealed 35% increase in critical load of adhesion for TiN-WSx/TiN dual layer structure as compared to TiN monolayer. Brittle flaking of TiN along edges of scratch track also became negligible for dual layer coating owing to presence to soft WSx as well as presence of hard under layer which hindered substrate deformation during scratching. Low hardness of TiN-WSx as compared to TiN, partially recovered owing to addition of hard TiN underlayer. The dual layer coating also exhibited significantly low coefficient of friction of approximately 0.25–0.3 relative to 0.7–0.8 for TiN. The hard TiN underlayer reduced ploughing of top TiN-WSx composite layer. This in turn, resulted in low wear loss and subsequently less accumulation of wear debris at the leading edge of the counterbody.

Mechanical Properties and Corrosion Resistance of NbTiAlSiZrNx High-Entropy Films Prepared by RF Magnetron Sputtering.

In this study, we designed and fabricated NbTiAlSiZrNx high-entropy alloy (HEA) films. The parameters of the radio frequency (RF) pulse magnetron sputtering process were fixed to maintain the N2 flux ratio at 0%, 10%, 20%, 30%, 40%, and 50%. Subsequently, NbTiAlSiZrNx HEA films were deposited on the 304 stainless steel (SS) substrate. With an increasing N2 flow rate, the film deposited at a RN of 50% had the highest hardness (12.4 GPa), the highest modulus (169 GPa), a small roughness, and a beautiful color. The thicknesses of the films were gradually reduced from 298.8 nm to 200 nm, and all the thin films were of amorphous structure. The electrochemical corrosion resistance of the film in a 0.5 mol/L H2SO4 solution at room temperature was studied and the characteristics changed. The HEA films prepared at N2 flow rates of 10% and 30% were more prone to corrosion than 304 SS, but the corrosion rate was lower than that of 304 SS. NbTiAlSiZrNx HEA films prepared at N2 flow rates of 20%, 40%, and 50% were more corrosion-resistant than 304 SS. In addition, the passivation stability of the NbTiAlSiZrNx HEA was worse than that of 304 SS. Altogether, these results show that pitting corrosion occurred on NbTiAlSiZrNx HEA films.

Influence of modulation frequency on the synthesis of thin films in pulsed magnetron sputtering processes

Abstract The research on the influence of modulation frequency on the properties of films synthesized using a unique pulsed power supply combined with a standard unbalanced circular magnetron was conducted in the process of pulsed magnetron sputtering (PMS). It was shown that by using different levels of modulation, the composition of plasma (measured by optical emission spectroscopy, OES) as well as film growth rate and morphology (observed with scanning electron microscope, SEM), can be changed. The impact of modulation is related to the used materials and gases and can vary significantly. It was concluded that modulation frequency can greatly influence the synthesis of materials and can be used as an additional parameter in PMS. Specific relations between modulation frequency and synthesized material require further investigation.

Effect of pulsed magnetron sputtering process for the deposition of thin layers of nickel and nickel oxide

Abstract Magnetron sputtered nickel and nickel oxide films have been studied for various applications. We may find, among others, these films in electrochromic display devices, in resistive type gas sensors, as metal electrodes in electronic devices, in solar thermal absorbers. Pure nickel films deposited using PVD technique possess good corrosion and wear resistant properties. Magnetron sputtering has several advantages in film deposition (in comparison to other methods) such as relatively low heating temperature of the deposited substrate during sputtering process, high energy of sputtered atoms (about 10 eV) at the substrate, which influences positively the films adhesion. From application point of view, the most valuable feature of these films is the possibility of scaling target dimensions, which makes feasible the deposition on a several square meter surfaces. The improvement of magnetron sputtering devices design may influence positively the optimization of the deposition technology and its efficiency. The thin nickel and nickel oxide films were prepared by pulsed magnetron sputtering using original type WMK magnetron device. Ni (99.9 %) has been used as a sputtering target of 100 mm in diameter and different thicknesses (3 mm, 5 mm, and 6 mm). The distance between the substrate and target was the same in all experiments and equal to 120 mm. Argon and oxygen gases were introduced during the reactive process through needle gas valves at a total pressure of 0.4 Pa. The sputtering power, sputtering pressure and oxygen partial pressure have been used as technological knobs for deposition processes. The helpful tool for controlling the pulsed magnetron sputtering process was the original parameter of supply (so called circulating power). Results from our experiments showed that the deposition of Ni films is possible even from targets of 6 mm thickness. Deposition rate increased proportionally with the sputtering power. The aim of this work is to use the acquired expertise to develop an efficient technology of thin nickel oxide layers for electrochromic systems.

Hard AlN films prepared by low duty cycle magnetron sputtering and by other deposition techniques

Crystalline AlN films are very attractive due to their properties such as high thermal stability and relatively high hardness and piezoelectric response. However, the deposition of dense textured AlN films with superior quality at a high deposition rate remains a challenge. In the present work, a reactive low duty cycle pulsed direct current magnetron sputtering (LDMS) process was employed to deposit AlN films on glass and silicon substrates. An arc-free discharge on the Al target was achieved by using short voltage pulses of 10 μs at a low duty cycle of 10%. The authors optimized the deposition conditions in terms of reactive gas flow, working pressure, average target power, substrate temperature, substrate bias, and the level of target erosion. With the optimized deposition conditions, the authors were able to obtain transparent crystalline AlN films with strong (002) preferential orientation and very good optical and mechanical properties: The AlN films with the highest refractive index of 2.1 present ...

A Contribution to explain the Mechanisms of Adhesive Wear in Plastics Processing by example of Polycarbonate

In the plastics industry, adhesive wear resulting from hot melt flow is one of the main damage mechanisms affecting extrusion tools. Such damages strongly influence the economic efficiency and the product quality. Due to their beneficial properties, Cr-based nitride hard coatings deposited by physical vapor deposition (PVD) are applied as protective coatings. These coatings can prevent the formation of iron oxides, which have an influence on the wetting of plastic melt on the tool surface. In the present work, four different CrAl-based nitride and oxynitride monolayer coatings were synthesized onto the tool steel substrate AISI 420 (X42Cr13, 1.2083) by means of a hybrid direct current and a high power pulsed magnetron sputtering (dcMS/HPPMS) process. Various Cr/Al metal ratios led to different chemical compositions of the nitride and oxynitride coatings. All coatings as well as one uncoated steel substrate were analyzed prior to and after long-term heat treatment as well as before contact angle measurements and after shear tests in order to investigate the influence of the respective processes on the chemical composition of the native passive film at the surface; analyses were run using X-ray photoelectron spectroscopy (XPS). Furthermore, the influence on the wetting behavior of polycarbonate melt was studied by means of high temperature contact angle measurements; the influence on the shear energy necessary for removing the solidified plastic droplet was investigated using shear tests. It could be shown that the heat treatment leads to a significant increase of polycarbonate wetting on the uncoated steel compared to the coated samples. Additionally, the coatings with an increased Al content exhibit a lower wetting rate compared to the other coatings and the uncoated steel. A beneficial effect of an oxidative post-treatment after deposition has been demonstrated.

Fundamental study of an industrial reactive HPPMS (Cr,Al)N process

In this work, a fundamental investigation of an industrial (Cr,Al)N reactive high power pulsed magnetron sputtering (HPPMS) process is presented. The results will be used to improve the coating development for the addressed application, which is the tool coating for plastics processing industry. Substrate-oriented plasma diagnostics and deposition of the (Cr,Al)N coatings were performed for a variation of the HPPMS pulse frequency with values from f = 300 Hz to f = 2000 Hz at constant average power P = 2.5 kW and pulse length ton = 40 μs. The plasma was investigated using an oscilloscope, an intensified charge coupled device camera, phase-resolved optical emission spectroscopy, and an energy-dispersive mass spectrometer. The coating properties were determined by means of scanning electron microscopy, glow discharge optical emission spectroscopy, cantilever stress sensors, nanoindentation, and synchrotron X-ray diffraction. Regarding the plasma properties, it was found that the average energy within the plasma is nearly constant for the frequency variation. In contrast, the metal to gas ion flux ratio is changed from JM/JG = 0.51 to JM/JG = 0.10 for increasing frequency. Regarding the coating properties, a structure refinement as well as lower residual stresses, higher universal hardness, and a changing crystal orientation from (111) to (200) were observed at higher frequencies. By correlating the plasma and coating properties, it can be concluded that the change in the gas ion to metal ion flux ratio results in a competitive crystal growth of the film, which results in changing coating properties.

Analysis of the properties of functional titanium dioxide thin films deposited by pulsed DC magnetron sputtering with various O2:Ar ratios

For the purpose of thin film preparation, pulsed DC magnetron sputtering process was performed and various O2:Ar gas ratios were applied during deposition. Structural properties of thin films deposited with various sputtering atmospheres were determined based on the results of the x-ray diffraction method and Raman spectroscopy, which revealed that all coatings were nanocrystalline and had anatase or rutile structure. The surface morphology of the coatings were investigated with the aid of a scanning electron microscopy and atomic force microscopy. Surface properties were evaluated by x-ray photoelectron spectroscopy and wettability measurements. It was revealed that an increase of Ar amount in the sputtering gas atmosphere caused as a result an increase of thin film water contact angle and enhanced ability of the surface to adsorb water molecules and hydroxyl radicals. Optical properties evaluated on the basis of transmission and reflection measurements showed that all coatings were transparent in the visible wavelength range, but had different refractive index, porosity and packing density. The mechanical properties of the obtained coatings were determined on the basis of nanoindentation tests. Prepared TiO2 thin films had different surface, optical and mechanical properties depending on the gas atmosphere during deposition.

Effective reactive pulsed magnetron sputtering of aluminium oxide – Properties of films deposited utilizing automated process stabilizer

The formation of dielectric composites on a target surface (target poisoning) reduces the deposition rate of a reactive magnetron deposition process in comparison to the deposition rate of metals. One way of minimizing this reduction is shifting the magnetron operating point from the dielectric to the transient mode. The goal of this paper is to show that a stable process of efficient aluminium oxide deposition can be carried out in a transient mode. An automated stabilizer driven by the electrical parameter of the magnetron power supply was used for process stabilization. The approach of process stabilization in the transient mode resulted in about seven times higher deposition rate of aluminium oxide than that of a standard dielectric mode and only two times lower than the deposition rate of aluminium. The optical properties of the thus obtained aluminium oxide films were studied by means of ellipsometric analysis. The model of film structure, consisting of stoichiometric aluminium oxide, metallic inclusions and voids, was proposed and dispersion characteristics were calculated. The complex refractive index characteristics were similar to those typical of aluminium oxide deposited during a standard pulsed reactive magnetron sputtering process.

(Cr,Al)N/(Cr,Al)ON Oxy-nitride Coatings deposited by Hybrid dcMS/HPPMS for Plastics Processing Applications

In plastics industry injection molding and extrusion tools are subjected to adhesive and abrasive wear by the flowing hot melt during extrusion process and adhering solidified melt. Due to their beneficial properties, Cr-based nitride hard coatings deposited by physical vapor deposition (PVD) are applied as protective coatings. In this regard, especially Cr-based oxy-nitride coatings with increased oxygen contents have a high potential to be used on plastic processing tools. In the presented work, five different oxy-nitride monolayer and bilayer coatings (Cr,Al)N/(Cr,Al)ON were synthesized on tool steel substrate AISI 420 (X42Cr13, 1.2083) by means of a hybrid direct current and high power pulsed magnetron sputtering (dcMS/HPPMS) process. Further, the coating architecture was varied in order to compare oxy-nitride monolayers with nitride coatings comprised of thin oxy-nitride top layers. All coatings were investigated with regard to their coating properties and, as defined by the corresponding coating/substrate interactions, with regard to their compound properties. The interactions between the coatings and Makrolon® 2408 polycarbonate (PC2408) were also characterized by means of high temperature contact angle and adhesive tensile strength measurements. Complementary, in-depth chemical analysis of the surface oxide regions of the coatings by means of X-ray photoelectron spectroscopy (XPS) was performed and revealed that the surface oxide composition is primarily determined by the oxygen concentration in the coating bulk. Further, this resulted into high contact angles of the polycarbonate melt, which is desirable for injection molding. All coated samples exhibited a better demolding behavior of the solidified plastic melt as compared to uncoated AISI 420.

The structural properties of CdS deposited by chemical bath deposition and pulsed direct current magnetron sputtering

Abstract Cadmium sulphide (CdS) thin films were deposited by two different processes, chemical bath deposition (CBD), and pulsed DC magnetron sputtering (PDCMS) on fluorine doped-tin oxide coated glass to assess the potential advantages of the pulsed DC magnetron sputtering process. The structural, optical and morphological properties of films obtained by CBD and PDCMS were investigated using X-ray photoelectron spectroscopy, X-ray diffraction, scanning and transmission electron microscopy, spectroscopic ellipsometry and UV–Vis spectrophotometry. The as-grown films were studied and comparisons were drawn between their morphology, uniformity, crystallinity, and the deposition rate of the process. The highest crystallinity is observed for sputtered CdS thin films. The absorption in the visible wavelength increased for PDCMS CdS thin films, due to the higher density of the films. The band gap measured for the as-grown CBD-CdS is 2.38 eV compared to 2.34 eV for PDCMS-CdS, confirming the higher density of the sputtered thin film. The higher deposition rate for PDCMS is a significant advantage of this technique which has potential use for high rate and low cost manufacturing.

Influence of Ar/Kr ratio and pulse parameters in a Cr-N high power pulse magnetron sputtering process on plasma and coating properties

Krypton is sometimes used in physical vapor deposition processes due to its greater atomic mass and size compared to argon, which leads to a lower gas incorporation and may have beneficial effects on kinetics of the coating growth. In this paper, the authors investigate the plasma composition and properties of deposited high power pulse magnetron sputtering Cr-N coatings for discharges with various Ar/Kr ratios and for various pulse lengths of 40 μs, 80 μs, and 200 μs, keeping the average discharge power constant. The results show that an addition of Kr influences the discharge process by altering the ignition and peak values of the discharge current. This influences the metal ion generation and growth conditions on the substrate by reducing the nucleation site densities, leading to a predominantly columnar grow. However, the deposition rate is highest for an Ar/Kr ratio of 120/80. The integral of the metal ion and atom emission exhibits the same trend, having a maximum for Ar/Kr ratio of 120/80. By decreasing the pulse length, the deposition rate of coatings decreases, while the hardness increases.