Hardness Of Thin Films Research Articles

Surface Instability of Bilayer Hydrogel Subjected to Both Compression and Solvent Absorption.

The bilayered structure of hard thin film on soft substrate can lose stability and form specific patterns, such as wrinkles or creases, on the surface, induced by external stimuli. For bilayer hydrogels, the surface morphology caused by the instability is usually controlled by the solvent-induced swelling/shrinking and mechanical force. Here, two important issues on the instability of bilayer hydrogels, which were not considered in the previous studies, are focused on in this study. First, the upper layer of a hydrogel is not necessarily too thin. Thus we investigated how the thickness of the upper layer can affect the surface morphology of bilayer hydrogels under compression through both finite element (FE) simulation and theoretical analysis. Second, a hydrogel can absorb water molecules before the mechanical compression. The effect of the pre-absorption of water before the mechanical compression was studied through FE simulations and theoretical analysis. Our results show that when the thickness of the upper layer is very large, surface wrinkles can exist without transforming into period doublings. The pre-absorption of the water can result in folds or unexpected hierarchical wrinkles, which can be realized in experiments through further efforts.

The evolution of hardness in Cu-W alloy thin films

A series of Cu-W films with the W content higher than 17.2 at% were prepared by magnetron sputtering focused co-deposition technology. The micro-structures and nanoidentation hardness of the films were investigated. Except for the fcc, amorphous and bcc phases, a novel multilayered structure has been observed at the range of about 17.2–90 at% W. Within the multilayered structure, the high-density interfaces can inhibit the motion of dislocations, which resulted in the hardness at least 2 GPa higher than that of the mixing rule. Depending on different microstructures, the hardness curve of the Cu-W films can be divided into three regions instead of the linear increase with the W content. From 17.2–40 at% W, the hardness increased slowly due to lots of amorphous phase. Within 40–65 at% W, the hardness increased linearly, which was caused by the gradually obvious multilayered structure and decreasing amorphous content. Above 65 at% W, single-phase body-centered cubic (bcc) films were observed. In this region, the upward trend of hardness slowed down due to the porous columnar structure and gradually disappeared multilayered structure.

Study on Oxidation Resistance of TiAlN Films Deposited by Magnetron Sputtering

In this paper, TiAlN hard thin film is deposited on hard alloy surface by magnetron sputtering; at 400 °C to 825 °C, oxidation experiment is performed for the samples; XRD is used for phase analysis of TiAlN hard thin film; Through the use of HVS-1000 digital micro-hardness tester and WS-2004 automatic scratching tester, microhardness of the samples and substrate-film adherence are analyzed. Results show: the microhardness and coherence of TiAlN thin film reduces with the rise of temperature; at 800 °C, the microhardness and substrate-film adherence remain at 1603 HV and 48 N respectively; it is found through comprehensive judgment that TiAlN thin film can work under 800 °C.

Assessment of Hard Thin Layers Deposited by Plasma Spray on Hydroboration

Chemical mixers used in pharmaceutic industry are mostly constructed from a series of iron, chrome and nickel alloys. These mixers are used for mixing corrosive chemicals (acid or base) that often contain solid particles acting as the abrasive particles on the mixer blades. In this paper, martensitic stainless steel AISI 415 is used as base material and powder based on tungsten carbide is used for deposition of hard thin film resistant at common action of abrasive particles. The properties of metallic materials can be improved by deposition of layers with special material by plasma spraying method. Microstructure of thin films made of tungsten carbide and base material was performed with Scanning Electron Microscopy (SEM). In order to determine the micro hardness of the base material and the deposited layer, Vickers micro hardness testing have carried out. For determination of roughness of the deposited layer, tests were carried out using the equipment Mitutoyo SJ 301.

Radiation stability of CBD grown nanocrystalline CdS films against ion beam irradiation for solar cell applications

Here we investigate the effect of swift heavy ion irradiation (SHII) on various properties of chemical bath deposited nanocrystalline CdS (nCdS) thin films. For this purpose, nCdS films are exposed to the varying ion fluences (1 × 1011–1 × 1014 ion/cm2) of 80 MeV O6+ ions. Glancing angle X-ray diffraction (GAXRD) and micro-Raman studies confirm almost negligible structural transformation in CdS after ion irradiation even at highest fluence i.e. 1 × 1014 ion/cm2. GAXRD, micro-Raman spectroscopy, field emission scanning electron microscopy and UV–Visible absorption spectroscopy studies suggest that the structure, shape and size of the particles as well as band gap of the nCdS films remain unaltered upon irradiation. The quality of the films and their radiation hardness is investigated by optical as well as electrical properties using photoluminescence spectroscopy and Hall measurements respectively. The films are found to be radiation resistant for 80 MeV O6+ ion irradiation as compared to other heavy radiations. The stability of various properties of nCdS films under the impact of SHII may be due to lesser or comparable value of electronic energy loss (Se) to the threshold value of Se. Radiation hardness of nCdS thin films is a good sign for fabrication of high performance, radiation stable and long lasting solar cell for extraterrestrial applications.

ZnO-carbon active nanostructured thin film fabrication by spin coating technique for enzymatic urea biosensing

Spin coated zinc oxide (ZnO)-carbon active porous media on the Fluorine-doped Tin Oxide (FTO) coated glass is presented as an engaged nomination for novel application in enzymatic urea biosensor. Some correlations between the processing parameters spinning speed, spinning duration, volume of solution and ZnO:carbon active ratio and respective thin film characteristics were determined, then uniform ZnO-carbon active the uniform film was achieved at the optimum deposition conditions. FE-SEM was employed to investigate the morphology and hardness of ZnO-carbon active thin film. The FE-SEM image illustrates cavities of a thin film as an efficient transducer area for immobilization of urease enzyme (Urs). Stepwise study of FTO/ZnO-carbon active/Urs biosensor manufacturing was performed by voltammetric and impedimetric techniques. The results revealed a good sensitivity for impedimetric urea retrieval between 8.0-110.0 mg dL-1 with detection limit of 5.4 mg dL-1.

The influence of gas flow rate on the structural, mechanical, optical and wettability of diamond-like carbon thin films

In this research, diamond-like carbon (DLC) thin films were deposited on silicon substrates by radio-frequency plasma enhanced chemical vapor deposition method using gas mixture of CH4 and Ar. The effect of different CH4/Ar gas ratio on the structure, refractive index, transmission and hardness of the DLC thin films were investigated by means of Raman spectroscopy, ellipsometry, Fourier transform Infrared Spectroscopy and nano-indentation methods, respectively. Nuclear resonant reaction analysis was used to measure the amount of hydrogen and carbon in the thin films. Furthermore, wettability of the thin films was achieved by measuring of water contact angle (WCA). The results indicated that the structural properties of the diamond-like carbon thin films are strongly dependent on the composition of gas mixture. Based on ellipsometry results, refractive index of the thin films varied in the range of 1.89–2.06 at 550 nm. FTIR results determined that deposition of DLC thin films on silicon substrate led to an increase of the light transmission in IR region and these films have the potential to be used in silicon optics as the antireflective coatings in this region. Nano-indentation analysis showed that the thin films hardness changed in the range of 7.5–11 GPa. On the other hand hydrogen content and fraction of C‒H bonds in the samples increased by an increase in the gas ratio of CH4/Ar. Also, WCA measurements indicated that WCA for thin films with gas ratio of 3/7 is the most and equal to 79°.

The structural and mechanical characterization of TiC and TiC/Ti thin films grown by DC magnetron sputtering

The formation of TiC and Ti phases and their influence on their mechanical properties was studied in this work. Thin layers were deposited by DC magnetron sputtering at room temperature in ultrahigh vacuum from Ti and C targets.Cubic TiC phase (c-TiC) was formed from 58 to 86 at.% Ti content. First formation of hexagonal Ti (h-Ti) occurred from 86 at.% Ti content. The c-TiC disappears from 90 at.% Ti content. Films with 86 at.% Ti content the c-TiC structure can transform to h-Ti by sequential stacking faults. Dominance of c-TiC(111) texture with increasing Ti content was observed.The hardness of thin films agree with structural observations. The highest hardness value (∼26 GPa) showed the c-TiC thin film with 67 at% Ti content. The nanohardness values showed decreasing character with increasing Ti content over 70 at.%. The lowest values of nanohardness (∼10 GPa) was observed for thin films with only h-Ti phase.

Fabrication and Characterization of Permanent Magnetic SmCo<sub>5 </sub>Thin Films by SQUID Magnetometer

Fabrication of hard magnetic thin films is a key issue on the development of new micro electro mechanical systems. As the magnetically hard SmCo thin-films offer excellent intrinsic magnetic properties, such as moderate saturation magnetization, large magnetic anisotropy, and high Curie temperature, they are considered as a promising candidate to be used for novel MEMS applications. In this work, SmCo5 thin films with Cu underlayer were grown onto Si (100) substrate at room temperature by RF magnetron sputtering technique. The samples were annealed at 400 ̊C and 500 ̊C under Ar atmosphere condition. Microstructural and magnetic properties of sputtered SmCo5 thin films were investigated by a number of advanced characterization tools and techniques. Phase composition of SmCo5 thin films was analyzed by grazing incident X-ray diffraction (GIXRD) with Cu-Kα radiation. Surface morphology was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. Magnetic force microscopy (MFM) technique was used to take stray-field images of SmCo5 thin films, and finally magnetic properties were investigated to explain the coercivity of SmCo5 thin films using superconducting quantum interference device (SQUID) as a magnetometer.

Improvement in Hardness of CrN Thin Film by Adding GaN and Evaluation of Its Solubility Limit

Improvement in Hardness of CrN Thin Film by Adding GaN and Evaluation of Its Solubility Limit

Formation mechanism of tungsten carbide hard thin film by wet plating and vacuum gas carburizing complex method

Formation mechanism of tungsten carbide hard thin film by wet plating and vacuum gas carburizing complex method

Combined Treatment of Fine Particle Bombarding and Hard Thin Film Coating

Combined Treatment of Fine Particle Bombarding and Hard Thin Film Coating

Dependence of Nitrogen/Argon Reaction Gas Amount on Structural, Mechanical and Optical Properties of Thin WNx Films

WNxfilms are deposited by reactive chemical vapor deposition at different amounts of nitrogen in gas mixtures. Experimental data demonstrate that nitrogen amount has a strong effect on microstructure, phase formation, texture morphology, mechanical and optical properties of the WNx films. With increasing nitrogen a phase transition from a single WN phase with low crystallinity structure to a well-mixed crystallized hexagonal WN and face-centered-cubic W2N phases appears. Relatively smooth morphology at lower N2 concentration changes to a really smooth morphology and then granular with coarse surface at higher N2 concentration. The SEM observation clearly shows a columnar structure at lower N2 concentration and a dense nanoplates one for higher nitrogen content. The hardness of WN thin films mainly depends on the film microstructure. The absorbance peak position shifts to shorter wavelength continuously with increasing nitrogen amount and decreasing particle size.

Ιntermetallic β-Ti3Au hard thin films prepared by magnetron sputtering

In the current study, we report on a deposition method to synthesize the intermetallic β-Ti3Au thin films by magnetron sputtering. We examine thin films crystallinity and structure-property relationships in terms of deposition conditions. The study is motivated by the vast application potential of β-Ti3Au, known to possess high hardness, interesting scratch and wear behaviors, and very good biocompatibility. The Ti1−xAux thin films (x=0–1) were deposited onto the Si(100) substrates by triple target magnetron sputtering under an Ar atmosphere and temperature varying from room temperature and to 650°C. The samples were characterized by X-ray diffraction (XRD) under grazing incidence and Bragg-Brentano geometries, scanning and transmission electron microscopy (SEM, TEM) equipped with an energy dispersive spectroscopy detector (EDS), and depth-sensing nanoindentation to investigate the dependence of the phase configuration, microstructure and mechanical properties on the Au/Ti ratio and deposition temperature. It was shown that upon varying the Au content the coatings develop a variety of single-phases or mixed structures composed of cubic, hexagonal and/or tetragonal phases of the binary Au-Ti system. At x=0.25, the compound Ti3Au developed a quasi-amorphous or defective nanocrystalline structures when deposited at room or low-temperatures, while a fully crystalline β-Ti3Au with an A15-type structure and lattice parameter of a=0.50925nm was obtained when deposited at 350–400 °C. The β-phase films exhibited a hardness of 10.4–12.1GPa, which is among the upper limits for intermetallic compounds, while the Young's modulus (173–201GPa) is fairly comparable to 209GPa predicted by first principles theoretical calculations. Thin film crystallinity and hardness strongly influenced both the deformation mode and the wear behavior under nanoscratch testing. The wear mechanisms changed from ploughing with ductile displacement, to microcutting with the formation of curly debris, to cracking with brittle fragmentation.

Investigation of structural network and mechanical properties of Titanium silicon nitride (TiSiN) thin films

Titanium silicon nitride (TiSiN) thin films were deposited on p-type c-Si (100) with different N2 flow rate by using chemical vapor deposition (CVD) technique. The microstructure, phonon modes, mechanical properties and compositional study of TiSiN thin films were characterised by scanning electron microscope (SEM), X-ray diffraction (XRD), Raman spectroscopy, nanoindentation and X-ray photoelectron spectroscopy (XPS),respectively. The SEM images show increases in surface roughness with increasing of N2 flow rate, however, improves the hardness and Young's modulus of TiSiN thin film. The XRD analysis reveals the presence of strain in TiSiN films. The estimated crystallites of TiSiN thin films was 7.51 and 7.39 nm for 40 and 100 sccm N2 flow rate. The XPS reveals the presence of 20 at. % Si content at 40 sccm N2 flow rate in the TiSiN film. To analyse the broad Raman spectra of TiSiN thin films, the peaks were convoluted into six individual Gaussian peaks. The quantitative and qualitative analysis XPS and Raman spectra of TiSiN thin films were carried out by using Origin 9.0 software.

Effect of Single and Duplex Thin Hard Film Coatings on the Wear Resistance of 1.2343 Tool Steel

In aluminum extrusion process, tool steels used as die materials suffer from mechanical, thermal and tribological stresses causing plastic deformation, wear and heat checking during hot metal flow. Thin hard film coatings like TiN, (Ti,Al)N and CrN are preferred in order to improve the surface properties of the tools. These coatings can reduce the friction force, minimize the adhesive interaction between the die and billet pairs and decrease the plastic deformation of the tool. In this study, effect of single (CrN and AlTiN) and duplex (CrN + AlTiN) thin hard films on the hot wear behavior of DIN 1.2343 tool steel was investigated. Wear tests were performed both at room temperature and elevated temperature to simulate the conditions of aluminum extrusion process. Based on the evaluation of coefficient of friction values, specific wear rates and worn surface examinations, the duplex coating, which had the best performance in the RT wear test showed good resistance to high temperature wear under the simulated aluminum extrusion conditions.

Structural and optical properties of gold-incorporated diamond-like carbon thin films deposited by RF magnetron sputtering

Pure and gold-doped diamond-like carbon (Au-DLC) thin films are deposited at room temperature by using RF magnetron sputtering in an argon gas-filled chamber with a constant flow rate of 100 sccm and sputtering time of 30 min for all DLC thin films. Single-crystal silicon (1 0 0) substrates are used for the deposition of pristine and Au-DLC thin films. Graphite (99.99%) and gold (99.99%) are used as co-sputtering targets in the sputtering chamber. The optical properties and structure of Au-DLC thin films are studied with the variation of gold concentration from 1%–5%. Raman spectroscopy, atomic force microscopy (AFM), Vickers hardness measurement (VHM), and spectroscopic ellipsometry are used to analyze these thin films. Raman spectroscopy indicates increased graphitic behavior and reduction in the internal stresses of Au-DLC thin films as the function of increasing gold doping. AFM is used for surface topography, which shows that spherical-like particles are formed on the surface, which agglomerate and form larger clusters on the surface by increasing the gold content. Spectroscopy ellipsometry analysis elucidates that the refractive index and extinction coefficient are inversely related and the optical bandgap energy is decreased with increasing gold content. VHM shows that gold doping reduces the hardness of thin films, which is attributed to the increase in sp2-hybridization.

Structure Stability and Mechanical Property of Y<sub>2</sub>O<sub>3</sub> Thin Films Deposited by Reactive Magnetron Sputtering

Y2O3 has a great application potential at reaction barrier coating of high-temperature composites due to its high thermodynamic stability and high melting point, and the phase structure stability at high temperature and structure dependent mechanical property are key parameters for this application. Y2O3 thin films were deposited on silicon (100) wafers by DC magnetron sputtering with various oxygen partial pressure and substrate bias, and then vacuum annealing at 1000°C was performed to investigate the phase structure stability. The microstructure, stress and hardness of as-deposited and annealed Y2O3 thin films were explored by X-ray diffraction, transmission electron microscope, and nanoindenter. The result showed that as-60 bias voltage was applied to substrate, cubic-c phase formed regardless of variation of oxygen partial pressure, and the cubic-c phase remains stability and crystallinity became better after annealing at 1000 °C.In addition, the hardness and modulus also just had minor changes as a function of oxygen partial pressure. As oxygen partial pressure was kept at 0.043 Pa, phase transition from cubic-c to monoclinic-b phase took place with increasing substrate bias, accompanying by the increment of hardness and modulus, and 1000 °Chigh-temperature annealing resulted in that as-deposited monoclinic-b phase transforms to cubic-c phase.

Morpho-Structural Characterization of WC20Co Deposited Layers

Hydroelectric power plants use the power of water to produce electricity. In this paper we propose a solution that will increase the efficiency of turbine operation by implementing new innovative technologies to increase the working characteristics by depositing hard thin films of tungsten carbide. For this purpose hard tough deposits with WC20Co and Jet Plasma Jet on X3CrNiMo13-4 stainless steel were used for the realization of the Francis turbine with vertical shaft.

Combinatorial study of Fe-Co-V hard magnetic thin films

Thin film libraries of Fe-Co-V were fabricated by combinatorial sputtering to study magnetic and structural properties over wide ranges of composition and thickness by high-throughput methods: synchrotron X-ray diffraction, magnetometry, composition, and thickness were measured across the Fe-Co-V libraries. In-plane magnetic hysteresis loops were shown to have a coercive field of 23.9 kA m–1 (300 G) and magnetization of 1000 kA m–1. The out-of-plane direction revealed enhanced coercive fields of 207 kA m–1 (2.6 kG) which was attributed to the shape anisotropy of column grains observed with electron microscopy. Angular dependence of the switching field showed that the magnetization reversal mechanism is governed by 180° domain wall pinning. In the thickness-dependent combinatorial study, co-sputtered composition spreads had a thickness ranging from 50 to 500 nm and (Fe70Co30)100-xVx compositions of x = 2–80. Comparison of high-throughput magneto-optical Kerr effect and traditional vibrating sample magnetometer measurements show agreement of trends in coercive fields across large composition and thickness regions.