Corrosion behaviour of CrN/Cr multilayers on stainless steel deposited by unbalanced magnetron sputtering

This paper reports the results of the influence of bilayer period (Λ) and total thickness (f) on the corrosion resistance of magnetron-sputtered CrN/Cr multilayers. Corrosion tests were carried out by potentiodynamic polarization with 0.5 M H₂SO₄ + 0.05 M KSCN solution and electrochemical impedance spectroscopy (EIS) with 3% NaCl solution. Measurements were also taken on the uncoated substrate and hard chromium coatings for comparison. Multilayer microstructure and morphology were studied by X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) and chemical composition was studied by energy dispersive X-ray analysis (EDX).The experiments showed that CrN/Cr coatings having lower bilayer period and lower thickness increased their efficiency as a barrier and improved the corrosion resistance of all coatings evaluated.     

Cr/CrN多层膜的结构及腐蚀性能研究

利用电弧离子镀设备,在45#钢基体上制备了两种调制比的Cr/CrN多层膜.采用X射线衍射技术(XRD)、扫描电子显微镜(SEM)、电子探针(EPMA)、M273A电化学系统等技术分析了薄膜的相结构、表面形貌、横截面元素分布、模拟海水中的抗腐蚀性能.结果表明:膜层主要由CrN、Cr2N和Cr组成,以Cr2N(111)为择优取向;膜层为Cr层-过渡层-CrN层的"三明治"调制结构;Cr/CrN多层膜结构与中间Cr层的存在可以显著提高基体和单层CrN抗腐蚀性能,45#钢+Cr/CrN(5/10)的防护体系抗腐蚀性能最佳.     

Microstructures and corrosion behaviors of Zr modified CrN coatings deposited by DC magnetron sputtering

Zirconium modified chromium nitride coatings with various Zr contents have been prepared by a DC reactive magnetron sputtering technique. The detailed investigations in terms of composition, phase structure, morphology and corrosion properties have been performed by GDOES, XRD, SEM and electrochemical measurements, respectively. The as-deposited coatings with Zr contents ranging from 0 to 3.2 at. % form nanocrystalline solid solutions, where Zr substitute Cr in the CrN lattice. With increasing Zr contents, the lattice parameters increase but the grain sizes show little effects. All the coatings exhibit dense compact columnar structures in SEM cross-sectional observations. Electrochemical measurements in 3.5% NaCl solutions revealed that the additions of Zr into CrN coatings improved their chemical inertness. The coated samples with much low corrosion current densities in nA/cm² range show their excellent protective characteristics to the stainless steel substrates. The corrosion mechanism, however, was due to the slight pitting corrosions, which were mainly localized in the growth defects.     

Analysis on microstructure and characteristics of TiAlN/CrN nano-multilayer films deposited by cathodic arc deposition

In this study, TiAlN/CrN multilayer thin films were deposited on SUS 403 stainless steel by cathodic arc deposition. The effects of substrate orientation (substrate surface parallel/perpendicular to target surface) and rotation speed were investigated in detail. Microstructure of the coatings was analyzed by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. Meanwhile, tribological and corrosion tests were performed. The experimental results showed that the as-deposited films exhibit a nano-scale multilayer structure consisting of TiAlN and CrN phases. The TiAlN/CrN multilayer films prepared by a parallel orientation and a rotation speed of 4 rpm not only possesses the best coating hardness and hardness/elastic modulus ratio, but also reveals superior abrasion resistance and corrosion resistance.     

Microstructure and hardness of SiC-TiC nanocomposite thin films prepared by radiofrequency magnetron sputtering

Silicon carbide-titanium carbide (SiC-TiC) nanocomposite thin films were prepared by radiofrequency magnetron sputtering using SiC-TiC composite targets fabricated by spark plasma sintering. The SiC thin films were amorphous at substrate temperatures below 573 K and crystallized in the cubic crystal system (3C) at substrate temperatures greater than 773 K. Cubic SiC-TiC nanocomposite thin films, which contain a mixture of 3C-SiC and B1-TiC phases, were obtained at a TiC content of greater than 20 mol%. The amorphous films possessed a dense cross-section and a smooth surface. The morphology of the SiC-TiC nanocomposite thin films changed from granular to columnar with increasing substrate temperature. The SiC-TiC nanocomposite thin films prepared at TiC content of 70-80 mol% and substrate temperature of 573 K showed the highest hardness of 35 GPa.     

Characterization and properties of CrN films deposited by ion-source-enhanced middle frequency magnetron sputtering

CrN films with deposition rates of 130-180 nm/min were deposited on Si (111) and carbamide alloy substrates by an ion-source-enhanced middle frequency magnetron sputtering system. Increasing of ion source voltages promoted the growth of CrN films with preferred orientation of (200). The deposited CrN films are composed of nanocrystalline particles with sizes of ∼20 nm embedded in polycrystalline matrix. The hardness of the CrN films increases from 1300 Kg/mm² without ion source bombardment to 2400 Kg/mm² with ion source voltages of 1000 V. Origins for the increasing of hardness can be attributed to dislocation strengthening and densification effects.     

Microstructure characterization of multilayered TiSiN/CrN thin films

Monolayered TiSiN and multilayered TiSiN/CrN coatings were synthesized by a cathodic arc deposition process. The chromium and Ti/Si (80/20 at.%) alloy targets were adopted as the cathode materials, altering the ratio of cathode current (I[TiSi]/I[Cr]) to obtain various multilayer periodic thicknesses of multilayered TiSiN/CrN coatings. X-ray diffraction and TEM analyses showed that all the deposited monolayered TiSiN and multilayered TiSiN/CrN films possessed the B1-NaCl structure. In this study, it was shown that the multilayer periods (Lambda) of the TiSiN/CrN deposited at I[TiSi]/I[Cr] cathode current ratios of 1.8, 1.0, and 0.55 were 8.3 nm, 6.2 nm, and 4.2 nm, respectively, with multilayer periodic thicknesses decreasing with smaller I[TiSi]/I[Cr] cathode current ratios. An amorphous phase was found at the boundaries of the TiN/CrN column grains. In addition, the multilayered TiSiN/CrN coatings displayed a lamellar structure that was well-defined and nonplanar between each TiN and CrN layer.     

Influence of substrate bias voltage on the microstructure and residual stress of CrN films deposited by medium frequency magnetron sputtering

In this study, CrN films were deposited on stainless steel and Si (1 1 1) substrates via medium frequency magnetron sputtering under a systematic variation of the substrate bias voltage. The influence of the substrate bias voltage on the structural and the mechanical properties of the films were investigated. It is observed that there are two clear regions: (1) below −300 V, and (2) above −300 V. For the former region, the (1 1 1) texture is dominated as the substrate bias voltage is increased to −200 V. The lattice parameter is smaller than that of CrN reported in the ICSD standard (4.140 Å) and the as-deposited films exhibit tensile stress. Meanwhile, the surface roughness decreases and the N concentration show a slow increase. For the latter region, the (2 0 0)-oriented structure is formed. However, the lattice parameter is larger as compared with the value reported in the ICSD standard, and the surface roughness increases and the N concentration decreases obviously. In this case, the compressive stress is obtained.     

Nitrogen doped p-type SnO thin films deposited via sputtering

p-Type SnO thin films were fabricated via reactive RF magnetron sputtering on borosilicate substrates with an Sn target and Ar/O₂/N₂ gas mixture. The undoped SnO thin film consisted of a polycrystalline SnO phase with a preferred (1 0 1) orientation; however, with nitrogen doping, the preferred orientation was suppressed and the grain size decreased. The electrical conductivity of the undoped SnO thin films demonstrated a relatively low p-type conductivity of 0.05 Ω⁻¹ cm⁻¹ and it was lowered slightly with nitrogen doping to 0.039 Ω⁻¹ cm⁻¹. The results of the X-ray photoelectron spectroscopy suggested that the nitrogen doping created donor defects in the SnO thin films causing lower electrical conductivity. Lastly, both the undoped and doped SnO thin films had poor optical transmittance in the visible range.     

High-temperature growth and in-situ annealing of MgZnO thin films by RF sputtering

We report the effect of growth temperature and annealing on microstructural, elemental and emission properties of as-grown and in-situ annealed MgZnO thin films, containing ∼ 10 at. % Mg, grown at high temperature by RF sputtering. Microstructural analysis carried out by TEM reveals formation of thin oxide layer with increased layer thickness on growth temperature, in the interface between Si substrate and MgZnO thin film. Irrespective of growth temperature, increase in Mg mole fraction with increase in thickness of MgZnO thin film is observed from EDX and AES spectroscopy, and a maximum of 14 at. % Mg is observed at 800 °C. The photoluminescence investigation shows blue shift of 104 meV in MgZnO film grown at 800 °C, compared to the film grown at 600 °C, which is due to the enhancement of the Mg incorporation at higher temperature. In addition, annealing at the growth temperature enhanced the intensity ratio of the UV/deep level emission and increased the grain size. Thermal treatment in a vacuum improved the emission efficiency and changed the origin of the point defects.     

Investigation of thin solid ZnO films prepared by sputtering

Zinc oxide (ZnO) thin films have attracted great attention in recent years due to their unique piezoelectric and piezooptic properties, making them suitable for various microelectronics and optoelectronics applications, such as surface acoustic wave devices, optical fibers, solar cells etc. ZnO is a semiconductor with a band gap of 3.3 eV and a large exciton binding energy of 60 meV. Undoped ZnO exhibits intrinsic n-type conductivity and it enables achieving high electron concentration. However, it may be doped to obtain low resistivity p-type thin films. Among group V of the periodic table, nitrogen is used as a popular p-type dopant due to its small atomic size. However, it is difficult to achieve p-type conduction in ZnO films due to the low solubility of nitrogen and its high intensity in self compensating process upon doping.Sputtering techniques enable us to form dense and homogeneous films due to the relatively high energy of the sputtered atoms. Thus we can grow high quality ZnO films with c-axis orientation, low growth temperature, high deposition rate, large area deposition, and availability in various growths ambient. In this work, the zinc oxide films were prepared using various DC sputtering methods in an atmosphere of pure argon and an atmosphere of mixed argon with nitrogen. Optical and electrical properties of the films were investigated.     

Influences of sputtering gas pressure and gas flow rate on microwave characteristics of FeCoAlO thin films

In this work, the influences of sputtering gas pressure and gas flow rate on the microwave characteristics of FeCoAlO thin films are investigated. All the high-frequency permeability spectra are discussed based on the Landau-Lifshitz-Gilbert equation. Although no obvious dependences on the pressure can be identified from the static magnetic hysteresis loops, the parameters obtained from the permeability spectra show strong dependences on the sputtering gas pressure. At 2 mTorr, the lowest damping factor and the highest anisotropy field are located. With the increase of gas flow rate, the resonance frequency decreases and frequency linewidth increases. Discussions infer that these dependences should be ascribed to the inner stress of the sputtered film which is influenced by the sputtering gas conditions.     

Optical and structural characteristics of ZnO thin films grown by rf magnetron sputtering

Nanostructured ZnO thin films on Pyrex glass substrates were deposited by rf magnetron sputtering at different substrate temperatures. Structural features and surface morphology were studied by X-ray diffraction and atomic force microscopy analyses. Films were found to be transparent in the visible range above 400 nm, having transparency above 90%. Sharp ultraviolet absorption edges around 370 nm were used to extract the optical band gap for samples of different particle sizes. Optical band gap energy for the films varied from 3.24 to 3.32 eV and the electronic transition was of the direct in nature. A correlation of the band gap of nanocrystalline ZnO films with particle size and strain was discussed. Photoluminescence emission in UV range, which is due to near band edge emission is more intense in comparison with the green band emission (due to defect state) was observed in all samples, indicating a good optical quality of the deposited films.     

Synthesis and tribological properties of WSex films prepared by magnetron sputtering

WSe_x films with variable Se/W ratio were deposited by non-reactive r.f. magnetron sputtering from WSe₂ target changing the applied d.c. pulsed bias conditions and substrate temperature. The structural and chemical properties were measured by cross-sectional scanning electron microscopy (X-SEM), energy dispersive analysis (EDX), X-ray diffraction (XRD), Raman and X-ray photoelectron spectroscopy (XPS). The tribological properties were measured in ambient air (RH = 30–40%) and dry nitrogen by means of a reciprocating ball-on-disk tribometer. A clear correlation was found between the Se/W ratio and the measured friction coefficient displaying values below 0.1 (in ambient air) and 0.03 (in dry N₂) for ratios Se/W ≥ 0.6 as determined by electron probe microanalysis (EPMA). The results demonstrated that notable tribological results could be obtained even in ambient air (friction ≤ 0.07 and wear rate ≈10⁻⁷ mm³ Nm⁻¹) by controlling the film microstructure and chemical composition. By incorporating carbon, wear and chemical resistance can be gained by formation of non-stoichiometric carbides and/or alloying into the defective WSe_x hexagonal structure. The existence of a WSe₂ rich interfacial layer (either on the ball scar or embedded in the film track) was evidenced by Raman in low friction conditions. The improvement in tribological performance is therefore obtained by means of layered WSe_x, the formation of gradient composition from metallic W (hard) to WSe₂ (lubricant) and carbon incorporation.     

Structure and properties of high power impulse magnetron sputtering and DC magnetron sputtering CrN and TiN films deposited in an industrial scale unit

Deposition of complex shaped or round-symmetric samples requires multi-fold substrate rotations during deposition or multiple cathode arrangements. The present paper investigates the influence of the high power impulse magnetron sputtering (HIPIMS) and DC magnetron sputtering (DCMS) process on the mechanical and tribological properties as well as the resulting structure of CrN and TiN coatings using static (0-fold) and dynamic (1-, 2- and 3-fold) depositions in an industrial scale unit. Furthermore, to increase the deposition rate without losing the high ion density in the plasma a hybrid HIPIMS/DCMS deposition technique is investigated. The results demonstrate the advantage of the HIPIMS technique when using multi-fold substrate rotation during deposition as it enables depositions of CrN_HIPIMS and TiN_HIPIMS coatings with hardness values around 23 and 35 GPa, respectively, compared with around 15 GPa for CrN_DCMS and TiN_DCMS coatings. Hardness values of 35 GPa for TiN_DCMS coatings prepared with substrate rotations could only be obtained when introducing an additional anode or using a multilayered CrN_HIPIMS/TiN_DCMS base layer as a template.Based on our results we can conclude that especially for up-scaling and multi-fold substrate rotations the HIPIMS process offers an improved performance as compared to DCMS.     

Optical properties of tungsten oxide thin films by non-reactive sputtering

Tungsten oxide thin films were grown on glass substrates by RF sputtering at room temperature using a tungsten trioxide target for several values of the argon pressure (P_Ar). The structural and morphological properties of these films were studied using X-ray diffraction and atomic force microscopy. The as-deposited films were amorphous irrespective of the argon pressure, and crystallized in a mixture of hexagonal and monoclinic phases after annealing at a temperature of 350 °C in air. Surface-roughness increased by an order of magnitude (from 1 nm to 20 nm) after thermal treatment. The argon pressure, however, had a strong influence on the optical properties of the films. Three different regions are clearly identified: deep blue films for P_Ar ≤ 2.67 Pa with low transmittance values, light blue films for 2.67 Pa < P_Ar < 6 Pa with intermediate transmittance values and transparent films for P_Ar ≥ 6 Pa with high transmittance values. We suggest that the observed changes in optical properties are due to an increasing number of oxygen vacancies as the growth argon pressure decreases.     

Surface characteristics of titanium targets and their relevance to sputtering performance

The early life performance of a titanium sputtering target is known to be influenced by the deformed layer generated at the sputter surface because of the machining operation and also by the level of surface contamination. As against earlier claims made by the other investigators, it is established that the removal of the entire deformed layer is not a requirement for the improvement of early life performance of a titanium sputtering target. A sputter treatment of the target surface for less than 20 min, using a simple air cooled magnetron sputtering chamber prior to the use in a commercial sputtering tool, improves the early life performance of a titanium sputtering target. It has been shown that this sputter treatment reduces the surface contamination level by removing a fraction of the deformed layer from the surface and also transforms the remaining deformed layer into a soft layer resembling the bulk titanium.     

CrN/ZrN纳米多层膜的合成及其结构和性能的研究

利用非平衡直流磁控双靶溅射在不同的基底转速(4～11r/min)和不同反应气体流量下制备一系列的具有纳米周期的CrN/ZrN多层膜.利用X射线衍射,俄歇电子能谱,X射线光电子能谱表征了薄膜的成分和结构,利用纳米力学测试系统以及摩擦磨损仪测量了薄膜的机械性能和摩擦磨损性能,分析了基底的转速、反应气体的种类及流量对薄膜结构与机械性能和摩擦磨损性能的影响.结果表明在氮中混入适量氨气条件下合成的具有小纳米周期的多层膜,其硬度可达32 GPa,磨损率可低到0.3865×10-5mm3/Nm,明显优于单质薄膜.低角度XRD分析证明了薄膜的多层结构.     

Studies on sputtering process of multicomponent Zr-Ti-Cu-Ni-Be alloy thin films

Sputter deposition process of a multicomponent Zr-Ti-Cu-Ni-Be metallic alloy has been studied experimentally and by numerical simulations. Monte-Carlo simulations were performed using a model based on thermalization and diffusion of sputtered atoms. Incident energy and angle of sputtered atoms on substrate were obtained from simulations. The incident angular distribution was observed to be a normal distribution at all sputtering pressures. Average incident kinetic energy of the condensing atoms on the substrate was observed to be 0.2-0.3 eV indicating most of them are thermalized. Simulations were extended to predict compositional variations in films prepared at various process conditions. These results were compared with composition of films determined experimentally using Rutherford Backscattering Spectrometry (RBS). Contents of Zr, Ti, Cu and Ni quantified using RBS were in moderate agreement with the simulated composition. Be could not be quantified accurately by RBS largely due to very low energy peak of Be in the spectrum. These studies are shown to be useful in understanding the complexities in multicomponent sputtering.     

Microanalysis of Pd and V-doped TiO2 thin films prepared by sputtering

Thin films of TiO₂ doped with vanadium and palladium, prepared by the magnetron sputtering method, were studied by means of X-ray diffraction (XRD), Scanning Electron Microscopy with Energy Disperse Spectrometer (SEM-EDS) and Atomic Force Microscopy (AFM). Investigations have brought important information about microstructure due to dopant incorporation in the TiO₂ host lattice. Directly after deposition thin films were XRD-amorphous and SEM investigations did not reveal details on the microstructure. Analysis of the topography of prepared thin films required application of Atomic Force Microscope. The AFM images show that as-deposited sample was dense with grain sizes varied in the range of 5.5 nm-10 nm, that indicated high quality nanocrystalline behavior. Additional annealing results in the formation of three phases in the thin film, e.g. (Ti,V)O₂ — solid solution, PdO and metallic inclusions of Pd. SEM-EDS system allowed analysis of the elemental composition, especially the V one, which lines have not been evidenced in the XRD diffraction pattern. EDS maps show homogenous distribution of elements Ti, O, V, Pd in prepared thin films.