Physical Vapor Deposition Technology Research Articles

Threading Performance of Different Coatings for High Speed Steel Tapping

Threading holes using tapping tools is a widely used machining operation in the industry. This manufacturing process involves a great tool immersion in the part, which involves both friction and cutting. This makes the use of coatings critical to improving tool life. Four coatings are used based on Physical vapor deposition (PVD) technology—TiN, TiCN, TiAlN and TiAlN+WC/C are compared to uncoated tool performance. The effect of various coatings on the life of M12 × 1.5 tapping tools during threading of through holes 20 mm deep, in GG25 casting plates, dry and applying cutting speed of 50 m/min. The end-of-life criterion has been established based on a cutting torque of 16 N-m. Taking the uncoated tap as a basis for comparison, it is observed that coatings based on PVD technologies increase tool life doubling in the most advantageous case with the TiAlN coating. PVD type coatings provide better protection to wear at cylindrical area of the tool, where the thread profile is finished, than uncoated taps. The teeth located in the cone-cylinder transition zone of the taps suffer the most wear regardless of the coating. However, taps coated with TiAlN+WC/C wear level values is lowest of all the coatings tested, which indicates a strong reinforcement in these teeth.

Biomimetic Coatings Obtained by Combinatorial Laser Technologies

The modification of implant devices with biocompatible coatings has become necessary as a consequence of premature loosening of prosthesis. This is caused mainly by chronic inflammation or allergies that are triggered by implant wear, production of abrasion particles, and/or release of metallic ions from the implantable device surface. Specific to the implant tissue destination, it could require coatings with specific features in order to provide optimal osseointegration. Pulsed laser deposition (PLD) became a well-known physical vapor deposition technology that has been successfully applied to a large variety of biocompatible inorganic coatings for biomedical prosthetic applications. Matrix assisted pulsed laser evaporation (MAPLE) is a PLD-derived technology used for depositions of thin organic material coatings. In an attempt to surpass solvent related difficulties, when different solvents are used for blending various organic materials, combinatorial MAPLE was proposed to grow thin hybrid coatings, assembled in a gradient of composition. We review herein the evolution of the laser technological process and capabilities of growing thin bio-coatings with emphasis on blended or multilayered biomimetic combinations. These can be used either as implant surfaces with enhanced bioactivity for accelerating orthopedic integration and tissue regeneration or combinatorial bio-platforms for cancer research.

Nb-doped TiO2 coatings developed by high power impulse magnetron sputtering-chemical vapor deposition hybrid deposition process

Novel methods for the deposition of thin functional coatings, such as hybrid physical vapor deposition-chemical vapor deposition (CVD) technologies, have the potential to become an important means of overcoming the limitations of current processes, such as low deposition rates, associated with some sputtering processes, or limited material/precursor choices, associated with CVD processes. This work explores the potential of addressing these issues through the development of a hybrid system, which combines the latest magnetron sputtering technology, high power impulse magnetron sputtering (HiPIMS), with plasma enhanced chemical vapor deposition (PECVD) technology. This system seeks to overcome the limitations of each technique and provide a new, flexible deposition tool for functional films, such as transparent conductive oxides. In this system, the plasma generated by the magnetron provides a source of electrons to drive the CVD precursor decomposition and reaction chemistry in the PECVD process. Consequently, only one power supply is required. Thus, niobium-doped titania coatings were deposited on glass and Si wafer substrates by this hybrid HiPIMS-CVD technique. The TiO2 coatings were deposited by CVD from a titanium (IV) tetraisopropoxide precursor via the vapor drawn method. The HiPIMS process provided not only the source of the Nb metal dopant to the functional films but also sustained the low temperature CVD process by supplying energetic plasma particles. Furthermore, since HiPIMS deposition rates are very sensitive to magnetic field strength and the degree of unbalance, by using a magnetron with variable magnetic field strength, it was possible to adjust the dopant content of the film without adjusting the power applied to the magnetron target. The effect of processing parameters (pulse frequency, peak powers, precursor flow rates, operating pressure, etc.) on generating a stable HiPIMS discharge across the process envelope has been studied. The composition and microstructure of the deposited coatings have been investigated, in respect to variable process parameters, such as substrate temperature and operating pressure.

The Influence of Laser Modification on a Composite Substrate and the Resistance of Thin Layers Created Using the PVD Process

For physical vapor deposition (PVD) technology, cleaning a substrate is one of the key preliminary processes before depositing the metal layer. In this article, we present the results of research on the modification of a textile composite substrate using laser technology and its influence on the surface resistance of silver structures intended for use in wearable electronics. As a result of the substrate modification, the resistance of the layers increased as compared with the structures produced on an unmodified substrate. An experimental planning technique was used to optimize the laser modification process.

Development and application of physical vapor deposited coatings for medical devices: A review

Abstract Physical vapor deposition (PVD) technology can modify the surface properties of equipment without changing the biomechanical properties of the substrate, and has been increasingly used in medical devices. Medical devices can be divided into surgical instruments, implantable medical devices and interventional medical devices according to the object and the way of application. For the defects of different medical devices during use, this paper reviews the development and application of PVD coatings to improve the performance and extend the life of medical devices. Finally, the development of PVD coatings for medical devices is expected.

Low-Cost Microwave Components’ Fabrication in Hybrid Technology of Laminates and Additive Manufacturing on an Example of Miniaturized Suspended Directional Coupler

A low-cost approach for the fabrication of low-loss microwave components in hybrid technology of laminates and additive manufacturing is presented in this paper. A standard copper-cladded printed circuit board technology is used in combination with a basic stereolithographic 3D printing technology and industry-standard physical vapor deposition technology of aluminum for manufacturing one of the basic building blocks of microwave systems – a 3-dB coupled-line directional coupler in suspended technique operating at 2.0 GHz band. A thin laminate with the coupler traces’ mosaic is suspended inside a metal-coated 3D printed enclosure. The presented study explores the performance of the circuit in terms of total power loss vs. the properties of deposited metallization layer serving as a ground plane. It is shown that when the surface roughness of the 3D printed enclosure is low enough, which can be achieved with the use of a layer of lacquer primer before metal deposition, the conductor-related power losses are lowered to an acceptable level. An exemplary directional coupler was developed along with three variants of the enclosure and the reference one. The measurement results validate the potential of this hybrid technique to deliver fully valuable microwave components at a very low manufacturing cost.

Synchrotron radiation characterization of magnetron sputtered WC-Co thin films on mild steel substrate

Mild steel offers versatile properties at lower costs. This has given the alloy a large application base in the industry. However, the increasing complexity and severity of service environments have shifted the focus of many industries to structure modification techniques, like physical vapor deposition to improve material properties and performance. Synthesis of WC-Co thin films by physical vapor deposition technology has attracted great research interest owing to the outstanding mechanical properties of the material and its potential to be utilized extreme engineering applications such as in wear-resistance, heavy cutting and excavation industries. The growth in the use of WC-Co thin films in the general mechanical industry is however slow due to lack of data on the tribological characteristics of WC-Co coated materials. Control and manipulation of synthesis parameters are of significant concern in order to tailor such material properties and performance. The focus of this paper is to, therefore, investigate the effect of Rf magnetron power and deposition temperature on the structure and sliding wear behavior of WC-Co thin film. The surface morphology and nature were acquired using x-ray photoelectron spectroscopy (XPS) and Grazing Incidence x-ray absorption spectroscopy (GI-XAS). To validate the synchrotron results, additional analysis was acquired from Scanning electron microscopy (SEM), Raman spectroscopy and surface profilometry to predict and point out optimum synthesis parameters for best properties of the film. Finally, the wear performance of the film-substrate system was determined and reported.

Corrosion mechanism investigation of TiN/Ti coating and TC4 alloy for aircraft compressor application

It is imperative to develop multifunctional erosion and corrosion resistant coatings for compressor blades of aircraft engines in harsh environment. PVD (Physical Vapor Deposition) technology has the advances in processing erosion-resistant coatings; however, the performance of PVD coatings to combat corrosion depends on various coating defects. Determining and comparing the corrosion performances of PVD TiN/Ti coating and uncoated TC4 alloy was the main objective of present work. The 960 h salt spray corrosion and 116 h hot corrosion tests were conducted to simulate the grounding and working environments of the aircraft compressors. The corrosion mechanisms due to the coating defects such as pinhole, columnar boundary and large grain were analyzed based on the OM, Confocal microscope, electrochemical measurements, SEM, XRD and EDS results. Owing to the disordered state associated with the columnar boundary and the coating defect, nitrogen could be easily replaced by oxygen in the hot corrosion process, these structures were channels for fast diffusion of oxygen. Moreover, the Gibbs energy changes of Ti oxidation and TiN oxidation were thermodynamically calculated according to the working condition of aircraft compressors, and considerable research effort was focused on mapping out the phase diagram of Ti, TiN and high pressure gases. The findings of this research can provide insights into developing multifunctional coatings for future aircraft engines.

Structure, mechanical characteristics and thermal stability of high speed physical vapor deposition (Al,Cr)2O3 coatings

In recent years (Al,Cr)2O3 coatings manufactured by physical vapor deposition (PVD) gained great interest as alternative to α-Al2O3 coatings deposited by chemical vapor deposition (CVD), due to their potential to form corundum-type structure at lower process temperatures, T ≤ 700 °C. In this context, also metastable tetragonal (Al,Cr)2O3 solid solution and semi-crystalline α-(Al,Cr)2O3 coatings were developed by high speed (HS)-PVD technology. The chemical analysis of the coatings in this paper confirmed, that the deposition of semi-crystalline α-(Al,Cr)2O3 coatings with high aluminum content, xAl ≥ 70 At.%, is possible at moderate substrate temperature, Tsub = 570 °C. With regard to the application on cutting and molding tools, the thermal stability of the developed coatings is of great interest. Therefore, the thermal stability of the deposited tetragonal and α-(Al,Cr)2O3 phases was investigated by annealing tests in vacuum up to T = 1300 °C. X-ray diffraction (XRD) measurements after the annealing tests in vacuum revealed a phase stability of semi-crystalline α-(Al,Cr)2O3 and metastable tetragonal (Al,Cr)2O3 coating up to T = 600 °C and T = 800 °C, respectively. Diffusion processes during annealing at high temperatures in vacuum lead to significant structural changes, showing detrimental effects on the mechanical properties of the coatings. Due to thermal induced structural, chemical and mechanical changes, the evaluations confirmed a thermal stability of the (Al,Cr)2O3 coatings up to a temperature of T = 800 °C in vacuum.

Post-annealing of (Ti,Al,Si)N coatings deposited by high speed physical vapor deposition (HS-PVD)

Gas turbine engines operating in environments containing solid particles such as sand, dust and ice particles are challenged by the problem of solid particle erosion (SPE), which causes contour changes especially on compressor blades. Consequently, the performance and efficiency of the engines as well as the maintenance intervals will be reduced. In order to minimize the effects of SPE and to extend the lifetime of compressor blades, the application of erosion resistant coatings represents a promising way.In the present work, (Ti,Al,Si)N coatings were deposited onto martensitic steel X3CrNiMo13-4 used for compressor blades by the high speed physical vapor deposition (HS-PVD) technology. Morphology of the coatings investigated by scanning electron microscopy (SEM) shows a dense microstructure with coating thickness s > 11 μm. Owing to hollow cathode discharge (HCD) and the transport function of the plasma-forming gas Ar, which are specific in HS-PVD deposition processes, high deposition rates ds/dt > 11 μm/h were achieved. The coated samples were then post-annealed directly in the coating chamber with varying atmosphere such as in vacuum and in nitrogen with or without bias voltage induced Ar-plasma. The post-annealing effects on the microstructure, indentation hardness as well as chemical and phase compositions were investigated by SEM, glow discharge optical emission spectroscopy (GDOES), X-ray diffraction (XRD) and nanoindentation, respectively. The erosion resistance of annealed, as-deposited and uncoated samples was investigated using a fine sand blasting facility. Basing on measured mass change and inspection of the eroded surfaces, a significantly higher erosion resistance of the (Ti,Al,Si)N coated samples compared to uncoated substrates could be revealed. Moreover, the post-annealing process led to a further improvement of the erosion resistance. Therefore, the thick (Ti,Al,Si)N coatings deposited by HS-PVD in combination with post-annealing in N2 atmosphere provide a high potential for the protection of compressor blades against SPE.

Understanding the deformation and cracking behavior of Cr-based coatings deposited by hybrid direct current and high power pulse magnetron sputtering: From nitrides to oxynitrides

The increasing demand for corrosion and wear reduction in modern tribological systems places high requirements on hard coatings deposited by physical vapor deposition (PVD) technology in numerous technical applications e.g., plastic processing, die casting or machining. One possible approach to withstanding the excessive wear is coating of tools with PVD hard coatings of the system Cr-Al-O-N. Each of the constituent elements can provide the coating with particular characteristics in point of its performance under different loading conditions. Therefore, the ongoing improvement in modern surface engineering requires comprehensive insights into the elastic-plastic deformation and cracking behavior of such coatings. For this purpose, several modifications and extensions of established experiments are required to overcome the limitations involved in characterization of thin hard coatings e.g., as a result of the μm ranges. In the presented work, three coatings CrN, (Cr,Al)N and (Cr,Al)ON deposited on quenched and tempered AISI 420 steel substrate were investigated. All coating systems were deposited through a hybrid technology, consisting of direct current and high power pulse magnetron sputtering (dcMS/HPPMS). The deformation and cracking behavior of the coatings and coating/substrate compounds were studied through application of static loadings by nanoindentation and Rockwell tests as well as dynamic loading conditions using nanoscratch tests. Complementary quantitative investigations were performed by means of depth profiling using confocal laser scanning microscopy (CLSM). Qualitative analyses of Rockwell imprints and nanoscratch tracks were conducted through scanning electron microscopy (SEM). Based on the results, precise analyses of nanoindentation force-displacement curves can improve the understanding about the possible crack formation in the coatings. Compared to (the binary) CrN, the ternary coating system (Cr,Al)N exhibits more promising characteristics in point of elastic-plastic deformation behavior and crack resistance. The crack resistance decreases through incorporation of oxygen into the ternary nitride and deposition of quaternary oxynitrides (Cr,Al)ON. Such character of oxynitrides can be overseen taking into consideration only the static loadings and therefore, applying of the both static and dynamic loading conditions are required to gain precise knowledge on the deformation and cracking behavior of thin hard coatings.

Thermal cyclic oxidation behavior of γ-TiAl with in situ post-annealed Al-Si-Y coating

A new in situ post-annealing process was applied to an Al-Si-Y-coated γ-TiAl substrate to enhance oxidation resistance. The process consisted of a diffusion treatment in vacuum and preoxidation in the coating chamber directly after the coating process. The coating deposition and the in situ post-annealing were conducted using high-speed physical vapor deposition technology. Results of cyclic oxidation tests performed at 950 °C for up to 1000 cycles demonstrated that the post-annealed Al-Si-Y coating has the potential to provide oxidation protection for γ-TiAl under thermal cyclic conditions, which parallels the real-life application conditions of low-pressure turbine blades.

MEVVA ion implantation of TiCN coatings; structural and tribological properties

The application of wear resistant metal nitride coatings, typically 2–5 μm thick, is a well-established strategy, employed for prolonging service life of cutting tools, twist drills, taps, dies. Although TiN is an established coating for such applications, in recent years attention has focused on a more diverse range of metal nitride coatings. Specifically, modifications to the TiN structure through the addition of C to produce TiCN are well established for improvement in properties such as friction coefficient and wear rates. Further improvements in tribological performance are expected by modifying the surface using ion implantation.In this exploratory study, TiCN coatings were deposited onto polished AISI 316 stainless steel substrates using commercially available physical vapor deposition technology. Coated samples were ion implanted with a range of metal ions to include Mo, Nb, W, Zr and Cr using the metal vapor vacuum arc (MEVVA) technique. Ions were implanted at a constant dose of 4 × 1016 ions/cm2.The range of techniques used to characterize the implanted layers included x-ray diffraction, Rutherford backscattering, and optical and atomic force microscopy. Dry sliding friction and wear behavior of implanted coatings was assessed using pin on disc equipment.The results showed that, with some exceptions, ion implantation generally improved friction and wear; in particular, implantation with Nb reduced stress levels, grain size, surface roughness, friction and wear rates.

A new approach to manufacture oxidation-resistant NiCrAl overlay coatings by electrodeposition

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.

Studies of the Electrochemical Properties of Thin-Film Materials for Coating Cardiac Stimulator Electrodes

The frequency characteristics of the admittances of a series of candidate materials for coating pacemaker electrode poles were studied. A method for assessing the properties of current transfer from an electrode connected to a source of stimulatory impulses to tissues is described. The main factors influencing decreases in the effectiveness of this transfer are identified. Potential physical vapor deposition technologies for depositing coatings, followed by alloying of films with metal ion beams, which increase the production of charged particles on the surfaces of the poles, are presented.

Influence of the Cr interlayer on the microstructure of sputtered TiN coatings deposited on zirconium alloy

On the surface of zirconium alloy, the TiN coatings with and without Cr interlayer were prepared in the N2/Ar mixed gas atmosphere by physical vapor deposition technology. The coatings morphology, micro-composition of surface particles, surface roughness, phase constituent and high-temperature oxidation resistance were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), roughness measuring instrument, x-ray diffractometer (XRD) and chamber electric furnace, respectively. The results show that, in comparison with the TiN coatings, the gray large particles increase in volume and the striated gullies reduce significantly for the Cr/TiN coatings. With the presence of Cr interlayer, the roughness of coatings increases, TiN (111) plane shows a weak growth, and the average grain size becomes small, while the average compressive strain increases. After the high-temperature oxidation test, there is a dense mixture of TiO2 and Cr2O3 on the surface of the Cr/TiN coatings which is continuous and complete without any defects such as cracks and holes. The Cr/TiN coatings enhanced the oxidation resistance of zirconium substrate, evidenced with 1/3 oxidation weight gain of that of the zirconium alloy. These results demonstrate the effectiveness of Cr/TiN coating as a protective coating on the zirconium alloy under extreme conditions.

Numerical Simulation Applied to PVD Reactors: An Overview

The technological evolution in the last century also required an evolution of materials and coatings. Therefore, it was necessary to make mechanical components subject to heavy wear more reliable, improving their mechanical strength and durability. Surfaces can contribute decisively to extending the lifespan of mechanical components. Chemical vapor deposition (CVD) and physical vapor deposition (PVD) technologies have emerged to meet the new requirements that have enabled a remarkable improvement in the morphology, composition and structure of films as well as an improved adhesion to the substrate allowing a greater number of diversified applications. Thin films deposition using PVD coatings has been contributing to tribological improvement, protecting their surfaces from wear and corrosion, as well as enhancing their appearance. This process can be an advantage over other processes due to their excellent properties and environmental friendly behavior, which gives rise to a large number of studies in mathematical modelling and numerical simulation, like finite element method (FEM) and computational fluid dynamics (CFD). This review intends to contribute to a better PVD process knowledge, in the fluids and heat area, using CFD simulation methods focusing on the process energy efficiency improvement regarding the industrial context with the sputtering technique.

Sintered powder-base cathode over vacuum-deposited thin-film electrolyte of low-temperature solid oxide fuel cell: Performance and stability

To expand the processing options for low-temperature-operating solid oxide fuel cells (LT-SOFCs), the hybridization of powder processing and vacuum deposition is attempted. Nanostructured nickel-yttria-stabilized zirconia (Ni-YSZ) anode functional layer (AFL) and YSZ/gadolinia-doped ceria (GDC) bi-layer electrolyte are fabricated over a sintered anode support by pulsed laser deposition (PLD), a physical vapor deposition technology. The most common powder-processed (screen-printed and sintered) La0.6Sr0.4Co0.2Fe0.8O3-δ-Gd0.1Ce0.9O1.95 (LSCF-GDC) composite cathode is applied over vacuum-deposited thin-film components. When LSCF-GDC is sintered at a general sintering temperature of 1050 °C then the continuity of the GDC buffer is lost and excessive interdiffusion between the cathode and the electrolyte has occurred at the interface. On the other hand, if the sintering temperature is lowered to 950 °C, peak power density more than 1.7 W cm−2 at 650 °C is obtained. Moreover, the operation stability of the hybrid SOFC (degradation rate ∼8%/100 h) is superior to that of the SOFC with a vacuum-processed nanostructure cathode (degradation rate ∼21%/100 h) when exposed to 0.7 A cm−2 at 650 °C, which is a significantly harsh degradation test condition for LT-SOFCs.

Al doped ZnO thin film deposition by thermionic vacuum arc

ZnO thin films are widely used in many application areas due to its various properties. The properties of the ZnO thin film strongly depend on the manufacturing method, doping elements and ratio and substrate material. In this paper, ZnO material was doped by Al element. Thermionic vacuum arc is a fast deposition technology for Al doped ZnO thin film manufacturing. TVA is physical vapor deposition technology, using anodic vacuum arc. It works under the high vacuum condition. The thin films were deposited onto amorphous glass, semi-crystal PET and single crystal Si substrate. Structural, morphological and optical properties of the Al doped ZnO thin films are presented. Thin films are in polycrystalline form and have high crystalline quality. According to the XRD analysis, metal oxide phases (ZnO and Al2O3) and bi-metal oxide (ZnAl2O4) phases were detected. It was found that crystallite sizes strongly depend on the substrate. The crystallite size of the thin film deposited on the Si substrate is approximately 100 nm. For the other sample, the value is very small; it is just about 20 nm. Considering the optical results of the samples, all films are transparent in visible region. Band gap and electronic structures of the Al doped ZnO thin films were investigated by optical method, photoluminescence and Raman spectra. The band gaps of the thin films were shifted towards to the high-energy region. Any impurity in deposited thin films cannot detect by the analyses devices.

Thick HS-PVD (Al,Cr)2O3 coatings for challenging cutting and die casting applications

In the last decades crystalline physical vapor deposition (PVD) Al2O3 coatings offered their great potential due to outstanding properties such as high hot hardness and wear resistance, especially concerning cutting applications. However, the properties of alumina strongly depend on the crystallographic phase. Thereby, the thermodynamically stable α-Al2O3 phase is the technical most interesting. The deposition of α-Al2O3 by chemical vapor deposition (CVD) is well-established, but requires high process temperatures, which reduce the selection of substrates. Another promising candidate concerning cutting and die casting applications is γ-Al2O3. The formation of γ-Al2O3 phase by PVD starts already at T ≥ 450 °C, allowing lower deposition temperatures. Regarding the wear protection of turning tools, a higher coating thickness (s ≥ 10 μm) is beneficial. A possibility to deposit thick PVD alumina coatings is the high-speed PVD (HS-PVD) technology. In the present work thick, s ≥ 20 μm, (Al,Cr)2O3 films are deposited on cemented carbides at substrate temperatures T ≥ 500 °C, by means of HS-PVD. A metallic (Cr,Al) bond coat was employed to improve the adhesion of (Al,Cr)2O3 coatings. In order to analyze the influence of the bond coat regarding the compound adhesion, scratch tests were conducted. For determining the coating morphology and thickness, scanning electron microscopy (SEM) was used. Phase analysis was carried out by X-ray diffraction spectroscopy (XRD). The mechanical properties were determined by means of nanoindentation. Regarding the use in high temperature applications, especially the formation of (Al,Cr)2O3 at substrate temperatures of T ≈ 850 °C indicates that the use of the coatings is possible at equal high temperatures without phase transformation.