Mechanical properties and bonding structure of boron carbon nitride films synthesized by dual ion beam sputtering

The BCN films were synthesized on Si (110) wafers by using dual ion beam sputtering deposition from boron carbide target. The influences of ion assist source energy and N₂ relative flow rate on the surface roughness, mechanical properties and chemical bonding structure of BCN films were investigated systematically. The surface roughness was measured using non-contact optical surface profilometer and the mechanical properties of BCN films were evaluated with nano-indenter. The BCN films were characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), respectively. The results showed that the BCN films' surface roughness varied in the range of 5–15 nm, and their hardness and reduced elastic modulus fluctuated in the scope of 18–29 GPa and 192–229 GPa, respectively. When the BCN films' surface roughness varied in the range of 8–12 nm, the values of hardness and reduced elastic modulus were fluctuated slightly. The BCN films with the smoothest surface (R_a = 5 nm) and the highest hardness of 28 GPa were obtained at the ion assist source energy of 200 eV and the N₂ relative flow rate of 50%. The BCN films were amorphous and contained several bonding states such as B–N, B–C and C–N with B–C–N hybridization.     

Influence of N2 partial pressure on mechanical properties of (Ti,Al)N films deposited by reactive magnetron sputtering

The influence of the nitrogen partial pressure on the mechanical properties of (Ti,Al)N films deposited by DC reactive magnetron sputtering using a Ti-Al mosaic target at a substrate bias of −100 V is investigated. Nanoindentation tests reveal that with increasing N₂ partial pressure, the film hardness and elastic modulus increase initially and then decrease afterwards. The maximum hardness and elastic modulus are 43.4 GPa and 430.8 GPa, respectively. The trend is believed to stem from the variations in the grain size and preferential orientation of the crystals in the (Ti,Al)N films fabricated at varying N₂ partial pressure. The phenomenon is confirmed by results acquired using glancing angle X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS).     

Microstructure and mechanical properties of nanolayered W/W–C thin films

The present study reports on the mechanical and structural properties of W/W–C multilayered thin films with bilayer periods Λ ranging from 2.5 to 100 nm. Films were grown by reactive sputtering radio frequency on Si (100) substrate. X-ray diffraction (XRD), grazing incidence X-ray diffraction (GIXRD) and X-ray reflectivity were used to globally characterise the multilayers structure. Hardness and Young modulus have been determined using nanoindentation with a Berkovich tip. The XRD and the GIXRD diagrams revealed the presence of three phases: WC_1−x randomly oriented, W₂C with (100) preferred orientation and W with (110) preferred orientation. An increase in hardness is observed with decreasing period Λ, reaching a maximum value of ~26 GPa at Λ = 2.5 nm.     

Local surface morphology and chemistry of SnO2 thin films deposited by rheotaxial growth and thermal oxidation method for gas sensor application

In this paper experimental results of a comparative X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS) study of the crystalline structure, the local morphology, and the surface and in-depth chemistry of SnO₂ thin films obtained by Rheotaxial Growth and Thermal Oxidation (RGTO) method are presented. XRD rules out even a minor presence of a coexisting SnO phase. AFM and SEM show a fractal like morphology of nanograins (20 nm typical size) agglomerated in clusters of crystallites with a bimodal size distribution. XPS shows that the surface of the SnO₂ crystallites is slightly under-stoichiometric as expected from the oxygen deficient termination of their facets. Noteworthy, as evidenced by XPS depth profiles, there are no significant changes of the surface chemistry of the RGTO film with argon ion sputtering.     

Effect of nitrogen partial pressure on the structure, physical and mechanical properties of CrB2 and Cr-B-N films

The investigation of structure and properties of Cr-B and Cr-B-N films deposited by direct current magnetron sputtering of CrB₂ target in argon and argon-nitrogen environments, respectively is presented. The nitrogen partial pressure was kept at 10, 15, and 25% of the total pressure. The microstructure, phase and chemical composition of Cr-B-(N) films were studied by means of X-ray diffraction, transmission- and scanning-electron microscopy, X-ray photoelectron spectroscopy, electron probe microanalysis and secondary neutral mass-spectrometry. The films were characterized in terms of their electrical resistivity, optical reflectivity and transmittance. Measurements of hardness and elastic modulus were performed by depth sensing nanoindentation. The results obtained show that the films deposited in pure Ar had a hexagonal AlB₂-type structure with crystallites, 15-17 nm in lateral size, elongated in the direction of film growth. The Cr-B-N films consisted of nanocrystalline nc-CrB₂ and amorphous a-BN phases. As the nitrogen content in films was raised, the volume fraction of the nc-CrB₂ phase decreased and a-BN phase increased. When nitrogen was added to the gas discharge during deposition, the nc-CrB₂ crystallite size decreased down to 3-5 nm. Without nitrogen, the films exhibited a columnar morphology. Nitrogen introduction suppressed the columnar growth of films because formation of a-BN intergranular layers. The films deposited under optimal parameters showed hardness in the range of 36-43 GPa and Young's modulus below 300 GPa. For all films, electrical resistivity values between approximately 200 and 700 µΩ cm were recorded.     

Investigation of structural,optical and micro-mechanical properties of (NdyTi1 − y)Ox thin films deposited by magnetron sputtering

TiO₂ and (Nd_yTi_1 − y)O_x thin films were deposited by reactive magnetron sputtering process from mosaic Ti–Nd targets and characterised by X-ray diffraction (XRD), Raman optical spectroscopy and nanoindentation technique. XRD measurements revealed that as-prepared titanium dioxide and TiO₂ thin films with 4 and 7 at.% of Nd had nanocrystalline rutile structure, while coatings with larger amount of Nd were amorphous. Raman spectroscopy investigations showed that the increase of the neodymium concentration caused amorphisation of the coatings and hindered their crystal growth. All as-prepared coatings were transparent in the visible wavelength range with a transmittance of approximately 80%. The refractive index and extinction coefficient of the thin films gradually decreased with the increase of the neodymium concentration. Micro-mechanical properties, i.e. hardness and elastic modulus, were determined using traditional load-controlled nanoindentation testing and continuous stiffness measurements. The highest hardness and elastic modulus values were obtained for thin films with 7 at.% of Nd and were approximately 14.8 GPa and 166.3 GPa, respectively.     

Effect of annealing temperature on the tribological behavior of ZnO films prepared by sol-gel method

The tribological behavior of zinc oxide (ZnO) films grown on glass and silicon (100) substrates by sol-gel method was investigated. Particularly, the as-coated films were post-annealed at different temperatures in air to investigate the effect of annealing temperature. Crystal structural and surface morphology of the films were measured by X-ray diffraction (XRD) and Atomic Force Microscopy (AFM). XRD patterns and AFM images indicated that the crystallinity and grain size of the films were enhanced and increased, respectively, with temperature. The tribological behavior of films was evaluated by sliding the ZnO films against a Si₃N₄ ball under 0.5 gf normal load using a reciprocating pin-on-plate tribo-tester. The wear tracks of the films were measured by AFM to quantify the wear resistance of the films. The results showed that the wear resistance of the films could be improved by the annealing process. The wear resistance of the films generally increased with annealing temperature. Specifically, the wear resistance of the films was significantly improved when the annealing temperature was higher than 550° C. The increase in the wear resistance is attributed to the increase in hardness and modulus of the film with annealing temperature.     

Structural characteristics and mechanical properties of Ti(Cr) films produced on Si substrate

A series of nanogranular Ti₉₀Cr₁₀ thin films have been fabricated by pulsed-laser deposition on Si substrates at different temperatures. The crystal structure and mechanical properties of these films were investigated. The X-ray diffraction and transmission electron microscope images with selected area diffraction showed that the structure of as-prepared films is dependent on film thickness and deposition temperature. It was found that the Ti₉₀Cr₁₀ films consisted of fine hexagonal close packed microstructure with columnar grains, while body close-packed cubic structure of Cr films are composed of irregular grains, meanwhile, a chromium disilicide (CrSi₂) layer formed in the interface between the substrate and Cr films which deposited at temperature of greater than 600 °C. The crystalline and columnar grains improved with an increase of the thickness of the films and an optimum microstructure is obtained under the present experimental condition of about 50 nm thickness and deposited temperature of 500 °C for Ti₉₀Cr₁₀ films. Deposited at 300 °C, the Ti₉₀Cr₁₀ films have hardness of 12.7 GPa and elastic modulus of 174.6 GPa. Improved to 600 °C the sample shows higher hardness of 13.1 GPa and higher elastic modulus of 183.2 GPa. Using Benjamin-Weaver model, adhesion shearing force can be calculated as 34.9 MPa for 300 °C Ti₉₀Cr₁₀ film while higher value of 44.4 MPa for higher temperature of 600 °C.     

Sol-gel synthesized SnO2 nanoparticles and their properties

Sol-gel synthesized SnO2 nanoparticles with an average size of 2.0 nm obtained at 373 K were gradually annealed to 673 K in air for 25 minutes. Sequentially taken transmission electron microscopy (TEM) images showed that particle agglomeration of these non-matrix SnO2 nanocrystals was a very slow process. The blue shifts of the band gap (approximately 2.3 eV) obtained from the optical absorbance spectra were matched with the theoretical results of the size related excitonic binding energies. These calculations also supported the observed slow grain growth. The depth sensitive hardness measurements of the thin films indicated hardness in the range of 5.03 GPa to 6.79 GPa. These undoped and non-matrix SnO2 nanoparticles were also investigated with the X-ray photoelectrons spectroscopy (XPS), atomic force microscope (AFM), X-ray diffraction spectroscopy (XRD), and ac impedance analyzer.     

Influence of the N2 partial pressure on the characteristics of CrZrN coatings synthesized Using a segment CrZr target

In this study, CrZrN films were synthesized by unbalanced magnetron sputtering (UBM) under various N2 partial pressures and their characteristics such as crystalline structure, surface morphology, microstructure and mechanical properties as a function of the N2 partial pressures were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), nanoindentation, wear tests, and corrosion tests. Results revealed that, with increasing the N2 partial pressure from 0.05 to 0.21 Pa, the nitrogen content of the films increased from approximately 40.9 to 53.7 at%, the deposition rate decreased from approximately 100 to 59 nm/min and the surface roughness (Rms value) was increased from approximately 0.57 to 1.79 nm. The Cr37.3-Zr9.0-N53.7 film has the highest hardness, elastic modulus, and plastic deformation resistance of 36 GPa, 380 GPa, and 0.41, respectively. The Cr37.3-Zr9.0-N53.7 film also has the lowest friction coefficient and wear rate of 0.19 and 3.01 (10(-6)m3/Nm) at room temperature. In addition, the potentiodynamic test results showed the corrosion resistance of the CrZrN films became increased significantly and their corrosion current density (i(corr)), corrosion potentials (Ecorr) and corrosion rate decreased with increasing N2 partial pressure.     

Microstructure and wear behaviour of silicon doped Cr–N nanocomposite coatings

Hard Cr–N and silicon doped Cr–Si–N nanocomposite coatings were deposited using closed unbalanced magnetron sputtering ion plating system. Coatings doped with various Si contents were synthesized by changing the power applied on Si targets. Composition of the films was analyzed using glow discharge optical emission spectrometry (GDOES). Microstructure and properties of the coatings were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and nano-indentation. The harnesses and the elastic modulus of Cr–Si–N coatings gradually increased with rising of silicon content and exhibited a maximum at silicon content of 4.1 at.% and 5.5 at.%. The maximum hardness and elastic modulus of the Cr–Si–N nanocomposite coatings were approximately 30 GPa and 352 GPa, respectively. Further increase in the silicon content resulted in a decrease in the hardness and the elastic modulus of the coatings. Results from XRD analyses of CrN coatings indicated that strongly preferred orientations of (111) were detected. The diffraction patterns of Cr–Si–N coatings showed a clear (220) with weak (200) and (311) preferred orientations, but the peak of CrN (111) was decreased with the increase of Si concentration. The XRD data of single-phase Si₃N₄ was free of peak. The peaks of CrN (111) and (220) were shifted slightly and broadened with the increase of silicon content. SEM observations of the sections of Cr–Si–N coatings with different silicon concentrations showed a typical columnar structure. It was evident from TEM observation that nanocomposite Cr–Si–N coatings exhibited nano-scale grain size. Friction coefficient and specific wear rate (SWR) of silicon doped Cr–N coatings from pin-on-disk test were significantly lower in comparison to that of CrN coatings.     

Thickness effect on properties of titanium film deposited by d.c. magnetron sputtering and electron beam evaporation techniques

This paper reports effect of thickness on the properties of titanium (Ti) film deposited on Si/SiO₂ (100) substrate using two different methods: d.c. magnetron sputtering and electron beam (e-beam) evaporation technique. The structural and morphological characterization of Ti film were performed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). XRD pattern revealed that the films deposited using d.c. magnetron sputtering have HCP symmetry with preferred orientation along (002) plane, while those deposited with e-beam evaporation possessed fcc symmetry with preferred orientation along (200) plane. The presence of metallic Ti was also confirmed by XPS analysis. FESEM images depicted that the finite sized grains were uniformly distributed on the surface and AFM micrographs revealed roughness of the film. The electrical resistivity measured using four-point probe showed that the film deposited using d.c. magnetron sputtering has lower resistivity of ～13 μΩcm than the film deposited using e-beam evaporation technique, i.e. ～60 μΩcm. The hardness of Ti films deposited using d.c. magnetron sputtering has lower value (～7·9 GPa) than the film deposited using e-beam technique (～9·4 GPa).     

正偏压作用下多弧离子镀ZrO2薄膜的组织结构与力学性能研究

在氧气和氩气的混合气体中,以O2/Ar流量比固定为1/4的条件,通过改变正偏压大小,采用多弧离子镀方法制备了新型高k栅介质——ZrO2薄膜。通过X射线衍射(XRD)和原子力显微镜(AFM)研究了在不同正偏压作用下正偏压值与薄膜的相结构、表面形貌之间的关系,利用纳米压痕仪测量了不同正偏压作用下沉积得到的ZrO2薄膜的硬度及弹性模量,并观察了ZrO2薄膜经不同温度退火处理后的相结构及表面形貌的变化。结果表明,在各个正偏压条件下,薄膜结构呈微晶或非晶;ZrO2薄膜的均方根粗糙度随着正偏压的升高而降低;正偏压为100V时硬度和弹性模量均达到最大值,分别为16.1GPa和210GPa。     

SiC/C薄膜的制备及其力学性能

以SiC 超细粉为原料、采用热等离子体物理气相沉积( TPPVD) 技术快速制备出了高质量SiC/ C 薄膜, 最大沉积速度达到225 nm/ s, 高于常规物理气相沉积( PVD) 和化学气相沉积(CVD) 法两个数量级。用扫描电子显微镜、高分辨透射电子显微镜和X 射线光电子谱对薄膜的形貌和微结构进行了观察和分析, 并用纳牛力学探针测定了薄膜的力学性能。研究结果表明, 向等离子体中导入CH₄, SiC/ C 薄膜沉积速度增大, 薄膜中C 含量增加, 薄膜断面呈现柱状结构。薄膜硬度和弹性模量随薄膜中C 含量增加而降低, 在接触深度为40 nm 时由纳牛力学探针测得沉积薄膜的最大硬度达到38 GPa。     

Microstructure and mechanical properties of TiAlN/SiO2 nanomultilayers synthesized by reactive magnetron sputtering

TiAlN/SiO₂ nanomultilayers with different SiO₂ layer thickness were synthesized by reactive magnetron sputtering. The microstructure and mechanical properties were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and nano-indentation. The results indicated that, under the template effect of B1-NaCl structural TiAlN layers, amorphous SiO₂ was forced to crystallize and grew epitaxially with TiAlN layers when SiO₂ layer thickness was below 0.6 nm, resulting in the enhancement of hardness and elastic modulus. The maximum hardness and elastic modulus could respectively reach 37 GPa and 393 GPa when SiO₂ layer thickness was 0.6 nm. As SiO₂ layer thickness further increased, SiO₂ transformed back into amorphous state and broken the coherent growth of nanomultilayers, leading to the decrease of hardness and elastic modulus.     

Effect of particle size on the in vitro bioactivity,hydrophilicity and mechanical properties of bioactive glass-reinforced polycaprolactone composites

Polycaprolactone (PCL) composite films containing 5 wt.% bioactive glass (BG) particles of different sizes (6 μm, 250 nm, < 100 nm) were prepared by solvent casting methods. The ultra-fine BG particles were prepared by high-energy mechanical milling of commercial 45S5 Bioglass® particles. The characteristics of bioactive glass particles were studied by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and X-ray diffraction (XRD) methods. In vitro bioactivity of the PCL/BG composite films was evaluated through immersion in the simulated body fluid (SBF). The films were analyzed by FE-SEM, energy dispersive spectrometry (EDS), XRD, and atomic force microscopy (AFM). The mechanical properties of highly-porous PCL/BG composites were examined on cylindrical specimens under quasi-static compression load. It was found that partial crystallization of amorphous BG particles during a prolonged mechanical milling occurred and calcium silicate (CaSiO₃) and sodium calcium silicate (Na₂CaSiO₄) phases were formed. The introduction of submicron BG particles (250 nm) was shown to improve the bioactivity of PCL films. In contrast to BG microparticles, the submicron BG particles were distributed on the film surfaces, providing a high surface exposure to SBF with an improved nanotopography. A notable increase in the stiffness and elastic modulus of the composite was also obtained. As compared to submicron BG particles, lower bioactivity and elastic modulus were acquired for PCL/BG nanoparticles. It was also shown that in spite of high specific surface area of the nanoparticles, partial crystallization during mechanical milling and agglomeration of the nanoparticles during processing decrease the bioactivity, hydrophilicity and mechanical response of the BG-reinforced PCL composites.     

Atomic force microscopy indentation of fluorocarbon thin films fabricated by plasma enhanced chemical deposition at low radio frequency power

Atomic force microscopy (AFM) indentation technique is used for characterization of mechanical properties of fluorocarbon (CF_x) thin films obtained from C₄F₈ gas by plasma enhanced chemical vapour deposition at low r.f. power (5-30 W) and d.c. bias potential (10-80 V). This particular deposition method renders films with good hydrophobic property and high plastic compliance. Commercially available AFM probes with stiff cantilevers (10-20 N/m) and silicon sharpened tips (tip radius < 10 nm) are used for indentations and imaging of the resulted indentation imprints. Force depth curves and imprint characteristics are used for determination of film hardness, elasticity modulus and plasticity index. The measurements show that the decrease of the discharge power results in deposition of films with decreased hardness and stiffness and increased plasticity index. Nanolithography based on AFM indentation is demonstrated on thin films (thickness of 40 nm) with good plastic compliance.     

Microstructural characteristics and mechanical properties of magnetron sputtered nanocrystalline TiN films on glass substrate

Nanocrystalline TiN thin films were deposited on glass substrate by d.c. magnetron sputtering. The microstructural characteristics of the thin films were characterized by XRD, FE-SEM and AFM. XRD analysis of the thin films, with increasing thickness, showed the (200) preferred orientation up to 1·26 μm thickness and then it transformed into (220) and (200) peaks with further increase in thickness up to 2·83 μm. The variation in preferred orientation was due to the competition between surface energy and strain energy during film growth. The deposited films were found to be very dense nanocrystalline film with less porosity as evident from their FE-SEM and AFM images. The surface roughness of the TiN films has increased slightly with the film thickness as observed from its AFM images. The mechanical properties of TiN films such as hardness and modulus of elasticity (E) were investigated by nanoindentation technique. The hardness of TiN thin film was found to be thickness dependent. The highest hardness value (24 GPa) was observed for the TiN thin films with less positive micro strain.     

Structure, mechanical and tribological properties of diamond-like carbon films on aluminum alloy by arc ion plating

The low hardness and poor tribological performance of aluminum alloys restrict their engineering applications. However, protective hard films deposited on aluminum alloys are believed to be effective for overcoming their poor wear properties. In this paper, diamond-like carbon (DLC) films as hard protective film were deposited on 2024 aluminum alloy by arc ion plating. The dependence of the chemical state and microstructure of the films on substrate bias voltage was analyzed by X-ray photoelectron spectroscopy and Raman spectroscopy. The mechanical and tribological properties of the DLC films deposited on aluminum alloy were investigated by nanoindentation and ball-on-disk tribotester, respectively. The results show that the deposited DLC films were very well-adhered to the aluminum alloy substrate, with no cracks or delamination being observed. A maximum sp³ content of about 37% was obtained at −100 V substrate bias, resulting in a hardness of 30 GPa and elastic modulus of 280 GPa. Thus, the surface hardness and wear resistance of 2024 aluminum alloy can be significantly improved by applying a protective DLC film coating. The DLC-coated aluminum alloy showed a stable and relatively low friction coefficient, as well as narrower and shallower wear tracks in comparison with the uncoated aluminum alloy.     

Growth of ZnO thin films at low temperature by plasma-enhanced atomic layer deposition using H2O and O2 plasma oxidants

Zinc oxide (ZnO) thin films were grown at 70 °C by plasma-enhanced atomic layer deposition using H₂O and O₂ plasmas. Plasma oxidants were used in order to improve the ZnO crystallinity and optoelectronic properties, avoiding high-temperature synthesis. The deposition parameters were optimized to achieve saturation in each reaction step. X-ray photoelectron spectroscopy (XPS) reveals high purity of the obtained ZnO films. X-ray diffraction (XRD) measurements indicate that the grown layers are polycrystalline and that the H₂O plasma synthesis leads to better crystallinity than the O₂ plasma as inferred from the intensity of the (100) and (002) peaks. The films are with high optical transmission, ~90%, as inferred from UV–visible (UV–Vis) transmittance measurements, and optical band gaps of 3.22 and 3.23 eV for H₂O and O₂ plasma, respectively. Atomic force microscopy (AFM) indicates that the films are smooth, with an average roughness of ~?0.22 nm. The growth rate was found to be in the range of 1.2–1.4 Å/cycle. The XPS, XRD, UV–Vis, and AFM results prove the possibility to obtain high-quality ZnO films by O₂ and H₂O plasma processes at 70 °C with chemical, structural, and optical properties promising for flexible electronics. ZnO films were successfully deposited on polyethylene terephthalate substrates using the optimal conditions for H₂O plasma process. No damage of the film surface or substrate was observed.