Direct Deposition Technique Research Articles

Multifunctional SiC nanowire aerogels with efficient electromagnetic wave absorption for applications in complex environments

In the digital age, with rapid advancements in electromagnetic (EM) technology, electromagnetic pollution has emerged as a significant concern. Traditional electromagnetic wave (EMW) absorption materials, however, are constrained by their limited application range, inadequate physicochemical stability, and inferior mechanical strength, hindering their further development and application. Consequently, there exists a demand for an EMW absorber that not only incorporates multiple functionalities but also retains essential physicochemical characteristics. In this context, this study introduces an ultralight (∼12 mg cm⁻³) and multifunctional SiC nanowire aerogel (SNWA), synthesized through a direct chemical vapor deposition (CVD) technique. The resulting SNWA demonstrates exceptional elasticity, outstanding mechanical durability, and high thermal stability at increased temperatures. Additionally, the enhanced SNWA shows improved hydrophobic properties, facilitating its use in highly humid conditions. The SNWA material also presents remarkable EMW absorption efficiency, with a minimum reflection loss of −50.6 dB and an effective absorption bandwidth of up to 7.7 GHz. The straightforward CVD synthesis and surface modification technique ensure the SNWA's durable and efficient performance in demanding environments.

Atmospheric Pressure Plasma Jet Synthesis and Characterization of Copper-Silver Bimetallic Materials as Electrocatalysts for CO2 Reduction

Copper-silver (Cu-Ag) bimetallics and alloys are attractive due to their enhanced performance compared to their parent metals in various fields including electronics, batteries, biomedicine, solar technology, energy storage, and catalysis.[1] Existing methods for synthesizing Cu-Ag bimetallics suffer from major drawbacks such as intense temperature and pressure conditions, pre and post-treatment processes, and multiple time-consuming steps.[2, 3]In this work, Cu-Ag bimetallic films were synthesized under various ratios for the first time using a newly developed Atmospheric Pressure Plasma Jet (APPJ) system. Synthesis was done in a single step, in under 15 minutes. The samples exhibited strong adhesion onto various substrates such as glass and glassy carbon. This direct-deposition technique requires low power input (<50 W) without the need for any pre- or post-treatment processes and with little to no waste. This contrasts with wet chemistry, where deposition normally takes 12-24 hours followed by thermal processes that produce several waste products.[4] Considering the high melting points (MP) of pure Cu and Ag (MP of Cu is ca. 1,085 °C and MP of Ag is ca. 962 °C), and the fact that they are immiscible, the formation of Cu-Ag alloys usually requires a high amount of energy under intense conditions.[5]These Cu-Ag films were characterized via cyclic voltammetry (CV), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Here, we demonstrate that by only mixing low-concentration metal salt solutions and using a neutral gas (helium), we can readily synthesize metal alloys while controlling their thickness, shape, composition, and metal ratios. From an electrochemical point of view, APPJ drives the reduction of metal cations from the presence of free electrons. This suggests the presence of a medium that is considered either as an electrode, due to the presence of electrons, or as an electrolyte, due to their electrical conduction.[6]These plasma-synthesized materials were tested as electrocatalysts for reducing atmospheric carbon dioxide (CO2) under various potentials. The performance of these catalysts was assessed via electrochemical surface area (ECSA), electrochemical impedance spectroscopy (EIS), and pulse voltammetry techniques. Copper is the only heterogeneous catalyst that converts CO2 into valuable chemicals, such as hydrocarbons, aldehydes, and alcohols.[7] Interestingly, we illustrate that the addition of silver improves the catalytic activity of copper toward CO2 reduction under low potentials. This is a desirable property given the anticipated transition to green energy. References Tantawy, H.R., et al., Novel synthesis of bimetallic Ag-Cu nanocatalysts for rapid oxidative and reductive degradation of anionic and cationic dyes. Applied Surface Science Advances, 2021. 3: p. 100056. Zhang, X., et al., Microstructures and properties of 40Cu/Ag (Invar) composites fabricated by powder metallurgy and subsequent thermo-mechanical treatment. Metallurgical and Materials Transactions A, 2018. 49: p. 1869-1878. Rajashekhar, B., et al., Electro co-deposition of copper-silver nanocrystallite alloy cluster: A way for tunable SERS substrate development. Materials Letters: X, 2022. 15: p. 100157. Jie, S., et al., Preparation of copper–silver alloy with different morphologies by a electrodeposition method in 1-butyl-3-methylimidazolium chloride ionic liquid. Bulletin of Materials Science, 2019. 42: p. 1-4. Banhart, J., et al., Electronic properties of single-phased metastable Ag-Cu alloys. Physical Review B, 1992. 46(16): p. 9968. Rumbach, P., et al., The solvation of electrons by an atmospheric-pressure plasma. Nature communications, 2015. 6(1): p. 7248. Kuhl, K.P., et al., New insights into the electrochemical reduction of carbon dioxide on metallic copper surfaces. Energy & Environmental Science, 2012. 5(5): p. 7050-7059.

Preparation and characterization of chromium oxide thin films: The response of morphology, crystal structure, and electrical properties to oxygen pressure under magnetron sputtering

This study focuses on Cr2O3 prepared via reactive magnetron sputtering, a direct deposition technique that significantly impacts the microstructure and optoelectronic properties of the films. Reactive sputtering alters grain size, density, and surface morphology, which in turn affects the structural order and stoichiometry. By adjusting the ratio of process gases, particularly the oxygen partial pressure, the stoichiometry of the deposited films was controlled. This is crucial for managing the oxidation state of chromium and the concentration of free electrons. An optimal oxygen partial pressure of 75 % was identified, substantially reducing oxygen interstitial defects in the CrOx materials and enhancing conductivity by nearly two orders of magnitude. Additionally, increasing the oxygen partial pressure helped integrate more oxygen atoms into the lattice, transitioning the electronic structure from a metallic state in CrO2 to a semiconductive state in CrO3. This fine-tuning of oxygen doping not only adjusts carrier concentrations but also optimizes the photoelectric properties of the materials, achieving a tailored high band gap of 3.34 eV. This study highlights the potential of reactive magnetron sputtering to customize semiconductor materials through oxygen doping, offering a novel approach to enhance the versatility and application range of chromium oxide materials in advanced technological applications.

Innovative NH3 separation over immobilized molten salt membrane at high temperatures

In industry, CO2 emissions can be mitigated by replacing conventional ammonia separation techniques withenergy-efficient systems. In this study, a ZnCl2 immobilized molten salt (IMS) membrane was synthesized and evaluated for the potential separation of NH3 from a gas mixture containing N2 and H2. The membrane was prepared via the direct deposition technique, and several permeation tests were performed to evaluate its permeation characteristics at atmospheric pressure with temperatures ranging from 290 °C to 325 °C. For single gas permeation at 300 °C, NH3 permeance was found to be as high as 182 GPU, with NH3/N2 and NH3/H2 ideal selectivities of 11,375 and > 107, respectively. For binary mixtures (10 %/90 % NH3/N2 and NH3/H2), NH3 permeance as high as 825 GPU was achieved at the same operating conditions. Remarkably, higher permeance (∼1100 GPU) was obtained by feeding ternary mixtures (11 %/67 %/23 % NH3/H2/N2) at a temperature of 325 °C. An exceptionally high NH3 purity (99.9 %) was achieved in the permeate stream. The IMS membrane exhibits prolonged stability, working for more than 180 h with no significant performance loss. This pioneering study shows that the ZnCl2 IMS membrane can be used to separate NH3 at high temperatures with a potential application for treating downstream ammonia in the industrial Haber Bosch process.

Fabrication of TiB whiskers reinforced Ti6242 matrix composites by direct laser deposition: Powder preparation, microstructure and mechanical property

Direct laser deposition (DLD) technique has great potential in manufacturing titanium matrix composites (TMCs) components with complicated shape. The TiB whiskers reinforced Ti6242 matrix composites were fabricated from the premixed TiB2/Ti6242 powders via DLD technique. Quantitative characterization of the extent of mixing uniformity and the deformation rate of the ball milled TiB2/Ti6242 powders was performed so as to select the optimal ball milling parameters. The TiB2/Ti6242 powders with two different weight fractions of TiB2 (2 wt%TiB2/Ti6242 and 5 wt%TiB2/Ti6242) were used to obtain different distributions of TiB whiskers in the composites due to the change in the solidification path in DLD process. The TiB whiskers in the TMCs-Ⅰ obtained from the 2 wt%TiB2/Ti6242 powders exhibited a discontinuous network structure following solidification in hypoeutectic zone, while the TiB whiskers were randomly distributed in the TMCs-Ⅱ obtained from the 5 wt%TiB2/Ti6242 powders due to the solidification in hypereutectic zone. In comparison with the DLDed Ti6242, the α colonies and β grains of the TMCs-Ⅰ and TMCs-Ⅱ were significantly refined. In addition, both equiaxed and lamellar α phase were formed in the TMCs-Ⅱ, in which various orientation relationships (ORs) between TiB and α phase occurred and the presence or absence of OR between TiB and β phase was responsible for the different morphologies of α phase. The yield strength of the DLDed TMCs-Ⅰ and TMCs-Ⅱ increased by 10.7 % and 38.8 % in comparison with that of the DLDed Ti6242, and both the load-bearing strengthening and fine-grain strengthening effects effectively enhanced the strength of the composites.

Investigating helium ion irradiation resistance in additively manufactured austenitic stainless steels

Additive manufacturing (AM) enables the rapid fabrication of complex shapes using engineering materials such as austenitic stainless steels and can imbue them with high irradiation resistance for use in reactor components. This is attributed to their refined grain structure and high grain boundary area. In this study, austenitic stainless steels (type 304) fabricated via direct energy deposition (DED) and powder bed fusion (PBF) techniques were irradiated with 5 MeV He ions to an approximate dose of 0.6 dpa at 300°C; subsequently, they were characterized through electron microscopy and the micro tensile testing. The results revealed that austenitic stainless steels manufactured using AM methods exhibited outstanding mechanical performance. The high performance of austenitic stainless steels fabricated through the DED technique can be attributed to their high tensile strength and excellent ductility elongation. This excellent performance is believed to be caused by the low stacking fault energy and the corresponding martensite formation during deformation. In particular, it was found that better mechanical properties were maintained even after helium irradiation, which is an important result obtained from the micro-tensile test. Even a small variation in the chemical composition and sub-microstructure of AM materials could result in improved irradiation tolerances.

Nanostructure evolution of reticular nano-TiB whiskers reinforced titanium matrix composite subjected to ultrasonic shot peening

Titanium matrix composites (TMCs) have drawn widespread attention because of their superior mechanical properties. In this study, nano-TiB whiskers reinforced TMC was fabricated using a direct laser deposition technique and then subjected to ultrasonic shot peening (USP) for different durations. The microstructure characterization results indicated that the surface grain refinement of αTi was dominated by complicated dislocation motion. The primary grain refinement mode during the microstructure evolution was the transverse splitting of the elongated lamellae. By interacting with dislocations, the TiB whiskers facilitated the evolution of nanostructures. After USP treatment, TiBw exhibited obvious fractures, but the TiB-Ti interface remained sharp and clear, showing excellent interfacial properties. The use of USP resulted in a significant compressive residual stress field, which increased with peening time. Surface hardness also increased as a result of fine grain and strain strengthening. When compared to the initial sample, the maximum microhardness of the sample after USP treatment increased by 48%.

Growth of Samarium-Substituted Epitaxial Bismuth Ferrite Films by Chemical Vapor Deposition

There is great interest in BiFeO3 and various substituted heterostructures for ferroelectric random-access memory (RAM) and energy-efficient magnetoelectric logic and memory devices. High-quality heterostructures of these material systems with smooth topography are desirable to incorporate into functional devices. For this purpose, the direct liquid injection chemical vapor deposition (DLI-CVD) technique has been employed to grow BiFeO3 and Bi-site samarium-substituted epitaxial films on (001)-oriented SrTiO3 and SrRuO3-buffered SrTiO3 substrates. Structural and morphological characterizations of the films are carried out using X-ray diffraction, atomic force microscopy, and scanning electron microscopy techniques. The films show textured growth and exhibit smooth morphology with root mean square roughness below 2.5 nm. Ferroelectric characteristics and memory retention in thin films are demonstrated using piezoresponse force microscopy. The thickness scaling of the switching voltage has been analyzed to validate the Kay–Dunn law for Sm-substituted BiFeO3 and compared with that of pure BiFeO3.

Assessing the quality and productivity of laser cladding and direct energy deposition: Guidelines for researchers

This paper provides guidelines and advice to researchers and engineers in the field of laser cladding and related direct energy deposition techniques to help establish a standardized approach to quality assessment and productivity metrics. Factors considered are deposit geometry, porosity, cracking, dilution, build-up/coverage rate, and powder catchment efficiency.

Enhancing the Shape Complexity in Direct Energy Deposition with Phased Deformation

Wire-based direct energy deposition (W-DED) techniques in metal additive manufacturing allow part-fabrication at higher deposition rates and lower costs. Given the lack of any support mechanism, these processes face challenges in fabricating overhanging features. The inherent overhang capability of weld-beads and higher-order kinematics can help realize certain complex geometries. However, significant challenges like non-uniform slicing, constrained deposition-torch accessibility, etc., limit the efficacy of these approaches. The present work describes a deformation-aided deposition process designed to overcome some of these limitations and to manufacture complex metallic components. It is based on a sequential combination of deposition and bending processes: a shape fabricated through W-DED deposition is bent to form the required shape. The cycle of deposition and bending is repeated until the final desired geometry is realized. The anisotropic and deterministic behaviors of the deposited components are analyzed in terms of springback and the punch force. Finally, the benefit of current hybrid process is demonstrated through a few illustrative geometries.

Investigation of the wear and corrosion behaviors of CrN films onto oxynitriding-treated AISI H13 alloy steel by the direct current magnetron sputtering process

• The optimal deposition time of CrN films onto oxynitriding-treated samples was 2.5 h. • Study confirmed that the 2.5 h specimen had the smaller surface roughness (20.5 nm). • 2.5 h specimen possessed the most stable columnar crystal structure of CrN films. • CrN/oxynitriding treated had the relatively lowest wear volume loss (5.38 × 10 −6 mm 3 ). • Duplex surface treatment possesses the lowest corrosion current (4.30 × 10 −5 A·cm −2 ). In the research reported herein, CrN films were coated onto oxynitriding-treated AISI H13 alloy steel using direct current magnetron sputtering deposition technique. The AISI H13 substrate has a 50-µm oxynitrided top layer with a hardness of 1000 HV 0.05 . The duration of the CrN film deposition were varied while the sputtering parameters were kept constant with constant bias of -25 V, power of 100 W, Ar and N 2 gas flow rate of 45 and 30 sccm, respectively, and deposition temperature of 300 °C. The duplex oxynitride/CrN coating exhibited optimal properties when the CrN film was 3.35 µm thick after 2.5 h deposition. This sample showed good adhesion to the oxynitrided layer. It also had the best wear resistance with wear loss volume and specific wear rate was 5.38 × 10 −6 mm 3 and 1.35 × 10 −6 mm 3 ·m − 1 ·N −1 , and good corrosion resistance with a corrosion current of 4.30 × 10 −5 A·cm −2 and polarization resistance of 604.66 Ω·cm 2 . Overall, the CrN/oxynitriding duplex surface treatment is effective in improving the properties of oxynitrided AISI H13 alloy steel.

Direct-Chemical Vapor Deposition-Enabled Graphene for Emerging Energy Storage: Versatility, Essentiality, and Possibility

The direct chemical vapor deposition (CVD) technique has stimulated an enormous scientific and industrial interest to enable the conformal growth of graphene over multifarious substrates, which readily bypasses tedious transfer procedure and empowers innovative materials paradigm. Compared to the prevailing graphene materials (i.e., reduced graphene oxide and liquid-phase exfoliated graphene), the direct-CVD-enabled graphene harnesses appealing structural advantages and physicochemical properties, accordingly playing a pivotal role in the realm of electrochemical energy storage. Despite conspicuous progress achieved in this frontier, a comprehensive overview is still lacking by far and the synthesis-structure-property-application nexus of direct-CVD-enabled graphene remains elusive. In this topical review, rather than simply compiling the state-of-the-art advancements, the versatile roles of direct-CVD-enabled graphene are itemized as (i) modificator, (ii) cultivator, (iii) defender, and (iv) decider. Furthermore, essential effects on the performance optimization are elucidated, with an emphasis on fundamental properties and underlying mechanisms. At the end, perspectives with respect to the material production and device fabrication are sketched, aiming to navigate the future development of direct-CVD-enabled graphene en-route toward pragmatic energy applications and beyond.

Investigation on structural and optical properties of porous SnO2 nanomaterial fabricated by direct liquid injection chemical vapour deposition technique

In the present study, Cassiterite SnO2 thin film synthesized by direct liquid injection chemical vapour deposition method. The surface morphology of the nanomaterial exhibited the rope-like structures with nanospheroid. Peak broadening in the prepared material is analyzed by Scherrer, modified Scherrer, Williamson-Hall, Size-strain and Halder-Wagner methods for investigation of crystallite size and intrinsic strain. The optical properties of the nanomaterial such as bandgap (Eg), absorption coefficient (α), skin depth (δ), optical density (Dopt), extinction coefficient (k), refractive index (n), and dielectric constants (εi and εr) are analyzed by using the UV–Visible transmittance and reflectance spectrum of the prepared SnO2 nanomaterial. The optical band gap of SnO2 based thin film was calculated by the Tauc plot and found to be 3.8 eV.

Application of Deep Learning models to characterize manufacturing defects in additive manufactured components

This work is part of a large package of work investigating the structural integrity of additively manufactured components in nuclear applications. Components manufactured using additive manufacturing (AM) often contain high degree of manufacturing defects which may lead to pre-mature failure in service conditions, for example, during fatigue loading. The aim of this work is to automate the detection and analysis of various types of manufacturing defects in AM using image segmentation techniques such that, robust predictive models can be built to correlate the defects with material deformation. The types of defects considered in this work are lack of fusion, micro-crack, spherical porosity, and unmelted particles.Four rectangular blocks of 316L stainless steel were fabricated using Selective Laser Melting (SLM) and Direct Lased Deposition (DED) techniques. The blocks were cut longitudinally, and the surfaces were metallographically polished and imaged using Scanning Electron Microscope (SEM). Deep neural network models were constructed based on three architectures: Fast Fully Convolutional Network (FCN), SegNet and UNet. The models were then trained using a set of micrographs utilizing various sets of hyperparameters. Model testing and validation were conducted using new and unseen images. Performance of the models were assessed based on training run times, testing run times and accuracy of detecting the correct locations, types, and sizes of the defects in the validation datasets.

Corrosion and slurry erosion wear performances of coaxial direct laser deposited CoCrFeNiCu1-xMox high-entropy coatings by modulating the second-phase precipitation

Developing high-entropy alloy (HEA) coatings with preferable properties for severe environments is a promising and cost-efficient way. In this work, an original HEA CoCrFeNiCu1-xMox coatings were designed on-demand and successfully prepared on duplex stainless steel (DSS) through coaxial direct laser deposition technique. The first-principles calculation based on the density functional theory was employed to calculate the characteristics of materials. The results showed that the uniformly distributed Cu could stabilize the face-centered cubic phase structure, hinder the transfer of point defects, and activate the cathode. The synergistic effect of Mo and other HEA elements was beneficial in reducing the point defect density of the passive film, and an appropriate amount of Mo was contributed to grain refinement, solid solution strengthening, and precipitation strengthening of the coating. When the ratio of Cu to Mo is 1:3, a small number of nanoscales second sigma phase (Fe-Cr-Mo) appeared between ordered and disordered, which balanced the coating's corrosion and slurry erosion wear performances. Compared with DSS, the corrosion current density of CoCrFeNiCu0.25Mo0.75 coating was reduced by nearly an order of magnitude, the impedance was increased by 2.5 times, and the erosion wear resistance was increased by 4 to 5 times.

Effects of TiC addition on microstructure, microhardness and wear resistance of 18Ni300 maraging steel by direct laser deposition

18Ni300 maraging steel with different TiC contents (0−10 wt.%), for the first time, have been fabricated by a direct laser deposition (DLD) technique. The microstructure and properties of the as-deposited and heat-treated samples have been carefully investigated. The obtained results show that the original 18Ni300 maraging steel exhibits extremely fine cellular microstructure with an average diameter of 3.7 μm, composed of martensite (M) and Ti2N. In contrast, the microstructure of the TiC-reinforced composites is significantly refined, in which the volume fraction of TiC formed with different morphologies varies with the TiC addition content. However, some cracks exist in the composite sample with the TiC addition up to 10 wt.%. The average microhardness of the as-deposited samples increases initially and then decreases with increasing TiC content, and the maximum microhardness (444 HV0.2) is obtained after adding 5 wt.% TiC. In addition, the sample with 5 wt.% TiC has been experienced a solution treatment at 850 ℃ for 1 h and then a subsequent aging treatment at 500 ℃ for 3 h. A number of nano-precipitates Ni3(Mo,Ti) and a few austenite are formed, which are dispersed in the martensite matrix after the heat treatment. This results in a high microhardness of 576 HV0.2 and a low wear rate of 1.37 × 10-6 mm3/(N·m), compared with those of the TiC-free sample (368 HV0.2 and 5.61 × 10-5 mm3/(N·m)), respectively. The possible microstructural mechanisms accounting for the property changes of the TiC-reinforced 18Ni300 maraging steel have been discussed in detail.

Universal interface and defect engineering dual-strategy for graphene-oxide heterostructures toward promoted Li–S chemistry

Li–S battery is broadly regarded as one of the most promising energy storage systems due to its prominent merits in energy density and theoretical capacity. Nevertheless, existing challenges such as formidable shuttle effect and sluggish redox kinetics hinder its practical application. Herein, we propose a universal interface and defect engineering dual-strategy to design graphene-oxide (G-oxide) hybrids as heterostructured electrocatalysts targeting promoted Li–S chemistry. The employment of direct plasma-enhanced chemical vapor deposition technique allows the in situ formation of graphene over a suite of oxide powders. Benefiting from the creation of heterointerface and carbon/oxygen defects, G-oxide realizes balanced management of polysulfide adsorption, lithium-ion migration and electron transportation, accordingly rendering bi-directional electrocatalysis behaviors for the sulfur conversion. Thus-assembled S/G-oxide cathode affords stable cycling performances even under a sulfur loading of 8.1 mg cm−2 and an electrolyte usage of 4.0 μL mg–1S.

Processing parameters in laser powder bed fusion metal additive manufacturing

As metallic additive manufacturing grew in sophistication, users have requested greater control over the systems, namely the ability to fully change the process parameters. The goal of this manuscript is to review the effects of major process parameters on build quality (porosity, residual stress, and composition changes) and materials properties (microstructure and microsegregation), and to serve as a guide on how these parameters may be modified to achieve specific design goals for a given part. The focus of this paper is on laser powder bed fusion, but elements can be applied to electron beam powder bed fusion or direct energy deposition techniques.

Effect of titanium oxide ceramic particles concentration on microstructure and corrosion behaviour of $$\text {Ni}$$–$$\text {P}$$–$$\text {Al}_{{2}}\text {O}_{{3}}$$–$$\text {TiO}_{{2}}$$ composite coating

Composite coatings are coatings that have been considered in terms of properties, such as corrosion resistance, oxidation resistance and excellent hardness. In this study, $$\hbox {Ni}$$ – $$\hbox {P}$$ – $$\hbox {Al}_{2}\hbox {O}_{3}$$ – $$\hbox {TiO}_{2}$$ composite coating was made on AISI 316 steel using direct current deposition technique. The microstructure of the coating and its corrosion resistance were studied by changing the amount of titanium oxide (1, 2, 3 and $$4~\hbox {g l}^{-1})$$ in the bath. To investigate the morphology of the coating and the analysis of the coated material, a scanning electron microscope (SEM) and EDS microscopy were conducted, respectively. The results showed that in the bath containing $$4~\hbox {g l}^{-1}$$ titanium oxide, the coating is perfectly uniform and continuous, while by reducing the amount of titanium oxide, it is not possible to form a suitable coating on the entire surface of the substrate. To investigate the corrosion resistance, the potentiodynamic polarization and electrochemical impedance spectroscopy tests in aqueous solution of 3.5% NaCl were carried out on coated and uncoated samples. The results of these tests were also correlated with microscopic images and showed that the coatings in a bath containing $$4~\hbox {g l}^{-1}$$ titanium oxide has the highest corrosion resistance.

Correlation between the Al content and corrosion resistance of TiAlN coatings applied using a PACVD technique

ABSTRACTThe present study aims to determine the effect of Al on the corrosion resistance of nanostructured TiAlN coatings deposited using a pulsed direct current plasma-assisted chemical vapor deposition (pulsed-DC PACVD) technique. The nanostructured TiAlN coatings were synthesized with three different Al-content values of by distinct precursor’s ratio of AlCl3-to-TiCl4. The number of AlCl3-to-TiCl4 precursor ratios was changed from 1 to 3 in order to vary the Al content. FE-SEM, XRD, EPMA and a Knoop micro-hardness tester were used to characterize the coated surfaces of the specimens. Electrochemical corrosion tests were carried out at 25 ± 1°C to investigate the corrosion behavior of the substrate and the TiN and TiAlN nanostructured coatings in 3.5 wt % NaCl solution. The results indicated that the potentiodynamic polarization plots revealed the passive behavior of TiAlN(2) nanostructured coatings that were more improved than the TiN, TiAlN(1) and TiAlN(3) coatings. Moreover, these curves showed that the TiAlN(2) nanostructured coating had an exceptional polarization resistance that was considered much higher than those of the substrate, TiN, TiAlN(1) and TiAlN(3) coatings. Also, the impedance spectroscopy plots showed that the TiAlN (2) coating had an exceptionally high polarization resistance compared to the substrate and other coatings.