Hybrid Deposition Technique Research Articles

Hybrid deposition of Cr–O/Al–O hard coatings combining cathodic arc evaporation and high power impulse magnetron sputtering

Arc-evaporated (Cr, Al)2O3 coatings with high hardness and excellent chemical inertness are promising protective layers for cutting tools. However, the high surface roughness restrains their further applications in advanced machining. In this work, Cr–O/Al–O coatings were fabricated using a hybrid deposition technique combining cathode arc evaporation and high-power impulse magnetron sputtering (HiPIMS) to reduce growth defects. Process conditions involving the gas inlet, duty cycle of HiPIMS, and bias potential were optimized to deposit Cr–O/Al–O coatings with high hardness. When the O2 inlet is close to the arc evaporation cathode, hybrid deposition can proceed stably and produce oxide coatings with an oxygen content above 50 at.%. The maximum hardness of 26.9 GPa for the Cr–O/Al–O coating was achieved at a duty cycle of 2.5 % and a bias potential of −50 V. In addition, the hybrid Cr–O/Al–O coating exhibits a dominated face-centered cubic structure with a nano-multilayer geometry formed by alternating Cr–O and Al–O sublayers.

Migration and agglomeration behaviors of Ag nanocrystals in the Ag-doped diamond-like carbon film during its long-time service

Silver-doped diamond-like carbon (Ag-DLC) films are considered as promising materials for the surface modification of mechanical components and biological implants. The long-term stability of Ag-DLC films is essential for their commercial use and requires intensive investigation. In this study, DLC and 10.0 at.% Ag-DLC films were prepared using a hybrid deposition technique, and the existence and evolution of Ag atoms over time were systematically studied. The results show that Ag atoms with a lower Ehrlich–Schwoebel barrier than that of C atoms are more prone to interlaminar diffusion, refining the columnar structure of DLC films and thereby creating a compact structure. In the as-deposited Ag-DLC film, Ag atoms mainly existed as fine nanocrystals with sizes ranging from 3 to 5 nm. Ag elements diffused with time during its long-time service, and fine Ag nanocrystals agglomerated to form large nanocrystals. The calculation results by density functional theory confirmed that the proximity of Ag atoms can lower the system energy, rendering agglomeration thermodynamically stable. Molecular dynamics simulations verified the spontaneous migration and agglomeration behaviors of Ag atoms over time. This study was focused on the evolution of Ag-DLC films over time and would provide guidance for their use in long-term applications.

High-entropy transition metal nitride thin films alloyed with Al: Microstructure, phase composition and mechanical properties

Deviation from equimolar composition in high-entropy multielement ceramics offers a possibility of fine-tuning the materials’ properties for targeted application. Here, we present a systematic experimental and theoretical study on the effects of alloying equimolar pentanary (TiHfNbVZr)N and hexanary (TiHfNbVZrTa)N high-entropy nitrides with Al. Although being predicted to be metastable by ab initio density-functional theory calculations, single-phase fcc NaCl-structured solid solution thin films with Al solubility limits as high as x ∼ 0.51–0.61 in (TiHfNbVZr)1-xAlxN and x ∼ 0.45–0.64 in (TiHfNbVZrTa)1-xAlxN are synthesised utilizing a hybrid deposition technique that offers dynamic mixing of film atoms from Al+ subplantation and non-equilibrium growth conditions leading to quenching of the desired film structure. In experimental studies supplemented with density-functional theory calculations, it is demonstrated that Al concentration in alloys with the multielement compositions of high-entropy nitride thin films determine hardness, yield strength, toughness, and ability to deform plastically up to fracture due to different deformation mechanisms arising from the electronic structure and phase compositions.

Microstructure, mechanical, and wettability properties of Al-doped diamond-like films deposited using a hybrid deposition technique: Bias voltage effects

In this study, Al-doped diamond-like carbon (DLC) films were prepared using a hybrid deposition technique combining high-power impulse magnetron sputtering and pulsed direct current magnetron sputtering. The influence of bias voltage effects on the microstructure and properties of films were investigated. The results showed that the deposition rate of the films decreased after increasing the bias voltage, and the Al content also slightly decreased in the films. All films exhibited a cauliflower-like surface morphology, which was independent of the bias voltage. The maximum values of sp2/sp3 and ID/IG were achieved without bias voltage; the ratios then monotonously decreased with an increase in the bias voltage from −100 V to −400 V, which indicates that the content of sp3-C bonds has improved in films. The mechanical properties and the wettability of the films were also evaluated. The results revealed that the hardness, elastic modulus and residual stress of the films increased with increasing bias voltage. The highest hardness occurred at −400 V, and the high sp3-C fraction and residual stress were beneficial to the hardness enhancement. All films exhibited a water contact angle greater than 100°, implying that the film possessed good hydrophobic performance. Specifically, when deposited at −300 V, the film presented a combination of superior properties, namely, a relatively high hardness and strong hydrophobic behavior.

Topology optimization and hybrid deposition technique for additive manufacturing of a brake caliper

Automobile parts like the brake calipers have always been manufactured by conventional manufacturing techniques. This research proposes an idea of combining the technologies of topology optimization and hybrid deposition to provide a novel manufacturing technique for a brake caliper that can fulfil the necessary application and has the advantage of reduced weight. Only optimizing the topology of the caliper will not be advantageous because it will highly affect the applicability of the component by removing some vital regions of the component. Thus, the combination of the two technologies ensures that topology optimization does not limit the application of the component in any form. The caliper was modelled and optimized in Autodesk Fusion 360™ and the deposition paths were developed in PrusaSlicer. The parent geometry and optimized geometry are overlapped one over the other for material deposition. Further, the research also compares the effects of changing parameters like percentage optimization and infill techniques and on the overall weight of the caliper. The results of the investigation can provide a new manufacturing technique for not just in the field of automobiles, but others as well.

Mechanism of protein biofilm formation on Ag-DLC films prepared for application in joint implants

Silver-doped diamond-like carbon (Ag-DLC) films offer low residual stress, good adhesion, and excellent wear resistance, and thus are promising materials for surface modification of joint prostheses. Further, as proteins are the most abundant component of joint fluid, the wear performance of Ag-DLC films in protein environments warrants investigation. We prepared DLC and 10.0 at.% Ag-DLC films using hybrid deposition technique by combining high-power pulsed magnetron sputtering and high-power pulsed plasma-enhanced chemical vapor deposition. The wear performance of the films was tested using bovine serum albumin (BSA) solution. A biofilm of denatured proteins formed at the friction interface of the Ag-DLC film, which improve wear resistance. Subsequent protein adsorption, Ag+ ions release, and spectroscopic evaluation of the interaction between Ag+ ions and BSA molecules revealed the mechanism of biofilm formation. Ag doping promoted the protein adsorption on film surface and friction interface of Ag-DLC films. Meanwhile, Ag-DLC films released Ag+ ions when exposed in physiological solutions. The released Ag+ ions break the hydrogen bonds and disulfide bonds in proteins and transform the α-helix structure to β-sheet and β-turn structure, thus unfolding the protein, exposing the inner hydrophobic groups, and inducing protein deposition and biofilm formation. The study elucidates the biofilm formation mechanism at the friction interface of Ag-DLC films and counterparts and can aid in design of hardwearing joint implants.

Influence of V addition on the microstructure, mechanical, oxidation and tribological properties of AlCrSiN coatings

The precise control of composition and out-diffusion/oxidation behavior of V element is the principal factor for V-containing coatings with superior mechanical and anti-wear properties at elevated temperatures. In this study, nanocomposite AlCrVSiN coatings were deposited by a hybrid deposition technique combining arc ion plating and pulsed DC magnetron sputtering. The influence of V content on the microstructure, mechanical, high-temperature tribological and oxidation properties of AlCrVSiN coatings was systematically investigated. The results showed that all the AlCrVSiN coatings exhibited a fcc-Cr(Al,V)N solid solution phase. With the increase of V content, the coating deposition rate increased from 14.0 to 25.2 nm/min, and the hardness of coatings firstly increased from 28.0 to 34.6 GPa and then decreased to 28.8 GPa. The incorporation of V into AlCrSiN coatings promoted the formation of lubricative oxides (e.g. V2O5), contributing a sharp decrease in friction coefficient of the AlCrSiN coatings from 1.0 to 0.56 and from 0.86 to 0.21 at 600 °C and 800 °C, respectively. The Al0.38Cr0.40V0.17Si0.05N and Al0.31Cr0.33V0.32Si0.04N coatings exhibited the best anti-wear property at 600 °C and 800 °C, respectively, determined by comprehensive influences of mechanical property, oxidation resistance and formation of lubricant tribofilm.

Microstructure and properties of TiAlCrN ceramic coatings deposited by hybrid HiPIMS/DC magnetron co-sputtering

TiAlCrN ceramic coatings were prepared utilizing a hybrid deposition technique consisting of High Power Impulse Magnetron Sputtering (HiPIMS) and Direct Current Magnetron Sputtering (DCMS). The chemical composition, phase structure, morphologies, mechanical and tribological properties of such coatings were systematically investigated. Results indicated that the content of Ti element increased monotonically from 0 at.% to 22 at.% with increasing of Ti target power. The TiAlCrN ceramic coatings presented a competitive growth tendency between (111) and (200) crystal plane through the energetic ion bombardment. Higher Ti target power resulted in stronger compressive intrinsic stress, which significantly suppressed the precipitation of hcp-AlN phase. With enhancing ion bombardment, diffusion energy and nucleation rate of adatoms on the growing surface increased, which caused a denser structure and ultra-smooth surface. The hardness and toughness also varied as a function of Ti target power, with the maximum hardness of 28.3 GPa under a Ti target power of 5 kW. Positive correlation between the adhesion strength (i.e., the critical load of the scratch test) and H3/E2 ratio was discovered indicating a strong dependence of adhesion properties on toughness for the TiAlCrN ceramic coatings in this study, which agreed well with the literatures. As for the tribological behavior, the lowest wear rate of 8.9 × 10-17 m3N-1m-1 was obtained for the TiAlCrN ceramic coating deposited at a Ti target power of 5 kW.

Influence of Ag doping on the microstructure, mechanical properties, and adhesion stability of diamond-like carbon films

Silver (Ag)-doped diamond-like carbon (Ag-DLC) films were deposited on Si wafer and Co-Cr-Mo alloy substrates using a hybrid deposition technique that combined high-power pulsed magnetron sputtering (HPPMS) and high-power pulsed plasma-enhanced chemical vapor deposition (HPP-PECVD). The Ag concentration (0.0–10.0 at.%) in Ag-DLC films was controlled by adjusting the number of Ag rods in the mosaic silver-graphite target. The effects of Ag doping on the microstructure, chemical bonding, mechanical properties, and adhesion stability of DLC films were systematically investigated. The results demonstrated that Ag doping could refine the columnar structure in DLC films and change the shape and size of DLC surface hillocks. The residual stress in the DLC films decreased as the Ag concentration increased, which effectively improved the adhesion between the films and substrates. The fraction of sp3 bonds in the carbon structure decreased with increasing Ag concentration, which resulted in a reduction in the film hardness when the Ag concentration was higher than 3.2 at.%. Ag doping could improve the wear performance of DLC films, and the Ag-DLC film with 3.2 at.% Ag had excellent wear resistance. Compared with pure DLC films, the Ag-DLC films had better adhesion stability in physiological solutions, which is beneficial for the long-term service of DLC films in vivo applications.

Influence of dry micro abrasive blasting on the physical and mechanical characteristics of hybrid PVD-AlTiN coated tools

The current study investigates the effect of the micro abrasive blasting (MAB) on the physical and mechanical characteristics of the cutting tools before and after coating deposition. Cutting tools were subjected to micro blasting by alumina (Al2O3) grains at varying pressure so as to improve the efficacy of the coating process. AlTiN coating of thickness 1.45 μm was deposited onto the tool surface by arc enhanced high power impulse magnetron sputtering (HiPIMS) hybrid deposition technique. The coatings were characterized using nano indentation, atomic force microscopy and micro scratch test. The results of nano indentations on the coated surface revealed the influence of the micro abrasive blasting technique and pressure on the superficial hardness. Surface morphology results showed better-adhered surface in case of cutting tools subjected to micro abrasive blasting before the deposition due to an increase in density of the nucleation sites for growth of aluminum which can be judged with the help of higher aluminum content in the energy dispersive x-ray analysis. The film adhesion of the coating onto the tool substrate is observed to be improved significantly with an increase in blasting pressure in the case of the samples subjected to micro abrasive blasting before coating. Additionally, X-ray diffraction analysis was performed to investigate crystallographic phases. The attained results provide insight concerning the optimum selection of micro abrasive blasting technique along with the pressure, for enhancing the cutting performance of coated tools during the machining of nickel-based superalloy Nimonic C 263.

Effects of bias voltage on the microstructure and properties of Al-doped hydrogenated amorphous carbon films synthesized by a hybrid deposition technique

Al-doped hydrogenated amorphous carbon films were deposited by a hybrid deposition technique combining middle-frequency magnetron sputtering and anode layer ion source. The evolution of chemical composition, surface morphology and chemical bonding state of the resultant films were investigated using XPS, SEM, TEM and Raman spectroscopy, respectively. It was found that the surface morphology of as-deposited films evolved from a rough surface with quasi-columnar characteristic to an ultra-smooth surface with the increasing of applied bias voltage from 0 V to −400 V. At the low bias voltage of 0 V to −50 V, a polymer-like structure was mainly formed. A diamond-like structure is dominated at the moderate bias voltage of −100 V to −300 V, while it transforms to graphite-like after a further increase of the applied bias voltage up to −400 V. The residual stresses and tribological behavior were characterized by stress-tester and ball-on-disk tribo-meter, respectively. The results suggested that tensile stress or compressive stress of the a-C:H(Al) film can be tailored by modifying the applied bias voltage. Particularly, the film deposited at −150 V exhibited a combination of superior properties, including low residual stress, high hardness, a low steady-state friction coefficient of 0.045 and wear rate of 2.7 × 10−7 mm3 N-1·m-1.

In-depth photoluminescence spectra of pure CIGS thin films

Photoluminescence spectra of pure CIGS thin films with different Ga in-depth gradients are systematically investigated. Pure Na-free films are prepared with an innovative hybrid deposition technique, whose optical luminescence emission is analyzed as a function of the depth and is correlated to the radiative intrinsic defects of the material. Finally, the highlighted features are correlated with the performances of test solar cells prepared with the same growths.

Integrated ECR-PECVD and magnetron sputtering system for rare-earth-doped Si-based materials

We report on a novel hybrid deposition technique to dope silicon-based materials with optically active elements in a plasma enhanced chemical vapor deposition (PECVD) process using a magnetron sputtering source. This approach is in contrast to traditional methods of rare-earth doping of PECVD films that utilise a metal organic precursor to introduce the rare earth species into the host matrix. We investigated the influence of the sputtering power applied to the rare earth metal target, in this case terbium, and the argon (Ar) partial pressure on the optical properties and composition of terbium-doped silicon oxide (SiOx:Tb3+) thin films. The film morphology was determined using high-resolution transmission electron microscopy, Rutherford backscattering spectrometry, and elastic recoil detection. We demonstrated that employing this novel technique provides a wider range of control of the doping level, yet delivers a similar rare earth (terbium) content to that which can be achieved using a traditional metal organic process. While the terbium concentration was strongly influenced by the sputtering power, it was only slightly affected by the Ar partial pressure. The refractive index was calculated from variable angle spectroscopic ellipsometry analysis and shows a direct relationship with the sputtering power whereas the film thickness shows an inverse relationship. The optically active Tb3+ ions were successfully excited within the silicon dioxide host matrix and the green Tb3+ emission was visible by the naked eye.

Microstructure and Mechanical Properties of Cu-Containing Amorphous Carbon Nanocomposite Thin Films by a Hybrid Deposition Technique

Microstructure and Mechanical Properties of Cu-Containing Amorphous Carbon Nanocomposite Thin Films by a Hybrid Deposition Technique

Over 100 cd A−1 Efficient Quantum Dot Light‐Emitting Diodes with Inverted Tandem Structure

Quantum dot light‐emitting diodes (QLEDs) with tandem structure are promising candidates for future displays because of their advantages of pure emission color, long lifetime, high brightness, and high efficiency. To obtain efficient QLEDs, a solution‐processable interconnecting layer (ICL) based on poly(3, 4‐ethylenedioxythiophene)/polystyrene sulfonate/ZnMgO is developed. With the proposed ICL, all‐solution‐processed, inverted, tandem QLEDs are demonstrated with high current efficiency (CE) of 57.06 cd A−1 and external quantum efficiency (EQE) of 13.65%. By further optimizing the fabrication processes and using a hybrid deposition technique, the resultant tandem QLEDs exhibit a very high CE over 100 cd A−1 and an impressive EQE over 23%, which are the highest values ever reported and are comparable with those of the state‐of‐the‐art phosphorescent organic LEDs. Moreover, the efficiency roll‐off, a notorious phenomenon in phosphorescent LEDs, is significantly reduced in the developed QLEDs. For example, even at a very high brightness over 200 000 cd m−2, the tandem QLEDs can still maintain a high CE of 96.47 cd A−1 and an EQE of 22.62%. The proposed ICL and the developed fabrication methods allow for realization of very efficient tandem QLEDs for next generation display and lighting applications.

Tunable SAW Devices Based on Ni:ZnO/ZnO/GaN Structures with Buried IDTs

Tunable RF devices have promising applications in low-power resettable sensors, adaptive signal processing, and secure wireless communications. We report a tunable surface acoustic wave (SAW) device built on a multifunctional ZnO/GaN-based structure. The device consists of a piezoelectric Ni:ZnO (NZO) layer deposited on the top of a ZnO/GaN semiconductor heterostructure. The multifunctional ZnO layers are made through a hybrid deposition technique: RF sputtering of a piezoelectric NZO layer and metallorganic chemical vapor deposition (MOCVD) of a semiconducting n-type ZnO layer on the GaN/Al2O3 substrate. This multifunctional and multilayer structure combines the large electromechanical coupling coefficient of ZnO and high acoustic velocities of GaN. The unique dispersion relationship in ZnO/GaN enables high-frequency (GHz) operation using higher order SAW modes. Two device configurations are designed: one with the interdigital transducer (IDT) exposed on the NZO surface, and one with the IDT buried inside NZO layer. Both devices operate at the GHz frequency. SAW frequency tuning is achieved by voltage controlled acoustoelectric interaction. The device using the buried IDT structure has better performance over the counterpart with exposed IDT SAW. The ZnO/GaN-based tunable SAW device with buried IDTs operating at 1.35 GHz has frequency tunability of ∼0.9% at low biasing voltage range (−12 V∼0 V).

Nitrogen-Incorporated Hydrogenated Amorphous Carbon Film Electrodes on Ti Substrates by Hybrid Deposition Technique and Annealing

A new method was adopted to fabricate the nitrogen-incorporated hydrogenated diamond-like carbon (DLC) film electrodes with TiN/TiCN/DLC multilayers on Ti substrates by a hybrid deposition technique and post annealing. The TiN and TiCN sublayers acted as adhesive layers and a nitrogen donor source for the DLC layer. Solid diffusion of nitrogen from these sublayers to the DLC layer occurred during annealing to form the N-incorporated DLC films. The electrical resistivity of the DLC films was significantly reduced by annealing process due to the graphitization and incorporation of N. The potential window of the DLC/Ti electrodes slightly decreased after annealing, while the electrochemical activity and catalytic ability of the electrodes for the redox of Fe(CN)63−/4− were significantly improved, which was attributed to the decreased resistivity and the active C-N function group on the electrode surface. The optimized annealing temperature was 800°C and the DLC/Ti800°C electrode exhibited comparable electrochemical characteristics with the boron-doped diamond electrode and superior properties than the Pt/Ti and glassy carbon electrodes, which made it promising electrode candidate for wastewater treatment. The correlations between the microstructure evolution and the electrochemical properties of the DLC films at various annealing temperatures were also systematically investigated.

Structural, electrical, and optical properties of amorphous carbon nitride films prepared using a hybrid deposition technique

Amorphous carbon nitride (a-CNx) thin films were prepared using a hybrid deposition technique (HDT), which is a combination of RF and DC magnetron co-sputtering of a graphite target. We varied the nitrogen gas flow ratio (GFR, N2/N2+Ar) during deposition to prepare a-CNx films with various nitrogen concentrations. The film properties were characterized using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The optical and electrical properties were also investigated. For 0.3<GFR<1, the optical band gap and resistivity increased with increasing nitrogen concentration (x=N/C) and sp3 C–N bonding fraction in the films. Compared to carbon nitride films with a comparable nitrogen content prepared by RF and DC sputtering, the optical band gap and resistivity of a-CNx films prepared by HDT were narrower and lower, respectively.

Properties of TiSiN coatings deposited by hybrid HiPIMS and pulsed-DC magnetron co-sputtering

TiSiN nanocomposites coatings were synthesized for the first time by a hybrid deposition technique where high power impulse (HiPIMS) and pulsed-DC (PDCMS) magnetron co-sputtering were used for Ti and Si deposition respectively in an Ar + N2 atmosphere. For the Ti target, the deposition parameters were fixed, while the current applied to the Si target ranged from 0 to 0.9 A. Thus, the Si content in the films was adjusted from 0 to 8.8 at.% Si to allows tailoring of microstructure and mechanical properties. TiSiN grain sizes decreased from ∼41 to ∼6 nm as the coatings became more siliceous. The hardness increased from 20 ± 0.41 to 41.31 ± 2.93 GPa when the Si concentration rose from 0 to 4.4 at.% Si, but beyond this last value, hardness degrades reaching 36.1 ± 2.21 GPa at 8.8 at.% Si. The wear behaviours evaluated by ball-on-disc tests were correlated with the Hardness/Young's modulus ratio. Moreover, the silicon enhanced the oxidation resistance and the least hardness deterioration was found in the sample with the higher silicon content (8.8 at.% Si) after a thermal annealing in air (2 h/700 °C).

Residual stress analysis of TiN film fabricated by plasma immersion ion implantation and deposition process

Titanium nitride (TiN) films were fabricated on AISI52100 bearing steel surface employing a hybrid plasma immersion ion implantation and deposition (PIIID) technique. The chemical composition, morphology and microstructure of TiN films were characterized by atomic force microscope (AFM), energy dispersive spectrometer (EDS), scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The residual stress of TiN films under different deposition parameter conditions were measured by means of glazing incidence angle X-ray diffraction (GIXRD) method. The influence of film thickness and X-ray glazing incidence angle on residual stress were investigated. AFM observation reveals that the TiN films have extremely smooth surface, high uniformity and efficiency of space filling over large areas. XRD analysis results indicate that TiN phase exists in the surface modified layer and exhibits a preferred orientation with the (200) plane. The GIXRD data shows that the residual stress in as-deposited TiN films is compressive stress, and the residual stress value decreases with the film thickness and increases with the glazing incidence angle. The compressive stress reduces from 2.164GPa to 1.163GPa, which corresponds to the film thickness from 1.5μm to 4.5μm, respectively. Reasonably selecting PIIID process parameters for TiN films fabrication, the residual stress in the film can be controlled effectively.